CN115898416A

CN115898416A - Construction method of tunnel in plateau area

Info

Publication number: CN115898416A
Application number: CN202211425232.2A
Authority: CN
Inventors: 饶胜斌; 王松涛; 张行道; 苏春生; 郭建强; 何十美; 陈潘峰; 邱贵山; 王言龙; 黄维明
Original assignee: China Railway Construction Bridge Engineering Bureau Group Co Ltd; Fifth Engineering Co Ltd of China Railway Construction Bridge Engineering Bureau Group Co Ltd
Current assignee: China Railway Construction Bridge Engineering Bureau Group Co Ltd; Fifth Engineering Co Ltd of China Railway Construction Bridge Engineering Bureau Group Co Ltd
Priority date: 2022-11-15
Filing date: 2022-11-15
Publication date: 2023-04-04

Abstract

The invention discloses a construction method of a tunnel in a plateau area, which comprises the following steps: s1, constructing a transverse hole; the method comprises the steps of advanced support, tunnel excavation, blasting construction, primary support, waterproof and drainage construction and lining construction; s2, carrying out jacking construction by entering the transverse tunnel into the main tunnel; constructing the joint position of the transverse hole and the main hole; and S3, constructing the main tunnel. The method combines the construction conditions and the topographic features of the plateau area, optimizes the construction process flow and the key working procedures in the construction process, well ensures the safety and the construction quality in the construction process, meets the requirements on the construction progress, and obtains good economic and social benefits in the construction application of the tunnel in the plateau area.

Description

Construction method of tunnel in plateau area

Technical Field

The invention belongs to the technical field of tunnel construction, and particularly relates to a tunnel construction method in a plateau area.

Background

With the rapid development of domestic infrastructure construction, the railway engineering traffic infrastructure gradually develops from plain areas to mountain areas and plateau areas, the construction number and mileage of tunnels are longer and longer, and great difficulty is brought to the construction of the tunnels; meanwhile, the conditions of thin air, low air pressure, cold, oxygen deficiency and the like exist in the plateau environment, and great difficulty is brought to the construction of the long-distance tunnel.

A certain tunnel construction project is located in a plateau mountain region, the tunnel has a long inner distance, the terrain and landform environment is complex, the tunnel is influenced by the altitude and the terrain, the construction condition is limited, and the safety of construction and the requirement of construction progress are difficult to guarantee by adopting a conventional construction method.

Disclosure of Invention

The invention aims to provide a construction method of a tunnel in a plateau area, which solves the problem that construction safety and construction progress are influenced by construction condition limitation in the plateau area.

The invention is realized by the following technical scheme:

the construction method of the tunnel in the plateau area comprises the following steps:

s1, constructing a transverse hole; the method comprises the steps of advanced support, tunnel excavation, blasting construction, primary support, waterproof and drainage construction and lining construction;

in the tunnel excavation step, adopt different construction methods to construct to different country rock ranks, include: constructing a grade III and a grade IV surrounding rock section by adopting a full-section method, and constructing a grade V surrounding rock section by adopting a micro-step method;

in the blasting construction step, segmenting the transverse tunnel according to the adopted construction mode, the surrounding rock grade and the lining type, classifying each segment of the transverse tunnel according to the adopted construction mode, the surrounding rock grade and the lining type, generating a corresponding blasting scheme according to the characteristic attributes of each segment of the transverse tunnel under different classifications, and blasting each segment of the transverse tunnel according to the blasting scheme;

s2, carrying out jacking construction by entering the transverse tunnel into the main tunnel; constructing the joint position of the transverse hole and the main hole;

gradually raising the arch top elevation of the transverse tunnel for construction when the transverse tunnel excavation construction is close to the main tunnel construction position; along the construction direction of the cross tunnel, constructing a shed tunnel from the intersection position of the main tunnel and the cross tunnel to enter the main tunnel, excavating the main tunnel in the intersection section of the cross tunnel and the main tunnel, climbing upwards in an inclined manner to excavate to the center line position of the main tunnel, and reaching the arch top elevation of the main tunnel; the shed tunnel is excavated forwards by a flat slope and is continuously constructed to the arch springing position of the upper step on the outer side of the main tunnel; constructing a shed frame in the shed tunnel while constructing the shed tunnel;

and S3, constructing the main tunnel.

As a further improvement to the above technical solution, in the blasting solution:

aiming at class III surrounding rock, a wedge-shaped cut construction mode is adopted, the circulating depth of depth is not more than 3.0m, peripheral holes are not ultra-deep, the ultra-deep of cut holes is not more than 0.4m, and auxiliary Kong Chaoshen is not more than 0.2m;

aiming at IV-level surrounding rocks, a wedge-shaped cut construction mode or a straight-hole cut construction mode can be adopted; when a wedge-shaped cut mode is adopted, the circulating depth is not more than 2.4m, the peripheral holes are not ultra-deep, the ultra-deep of the cut hole is not more than 0.4m, and the auxiliary Kong Chaoshen is not more than 0.2m; when a straight-hole cutting mode is adopted, the depth of the circulating depth is not more than 2.4m, peripheral holes are not ultra-deep, the ultra-depth of a cut hole is not more than 0.4m, auxiliary Kong Chaoshen is not more than 0.2m, and crushing Kong Chaoshen 0.2.2 m;

a straight-hole cut construction mode is adopted for V-level surrounding rock, the circulating depth of depth is not more than 1.0m, peripheral holes are not too deep, the ultra-depth of cut holes is not more than 0.2m, and auxiliary Kong Chaoshen is not more than 0.2m.

aiming at class III surrounding rock, the pitch of peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling Kong Kongju are not more than 50cm, the row pitch between tunneling holes is not more than 70cm, the hole pitch of a bottom plate is not more than 80cm, and the row pitch between the bottom plate hole and a blast hole positioned on the upper side of the bottom plate hole is not more than 80cm;

aiming at IV-grade surrounding rock, when a wedge-shaped cut construction mode is adopted, the pitch of peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling Kong Kongju is not more than 50cm, the row spacing between the tunneling holes is not more than 80cm, the hole pitch of a bottom plate is 80-100cm, and the row spacing between the bottom plate hole and a blast hole positioned on the upper side of the bottom plate hole is not more than 80cm; when a straight-hole undermining construction mode is adopted, the hole pitch of the peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling Kong Kongju are not more than 50cm, the row pitch between the tunneling holes is not more than 60cm, the hole pitch of the bottom plate is 80-100cm, and the row pitch between the bottom plate hole and the blast hole positioned on the upper side of the bottom plate hole is not more than 80cm;

aiming at the V-level surrounding rock, the hole pitch of the peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling holes Kong Kongju are not more than 50cm, the row pitch between the tunneling holes is not more than 100cm, the hole pitch of the bottom plate is not more than 80cm, and the row pitch between the bottom plate hole and the blast hole positioned on the upper side of the bottom plate hole is not more than 100cm.

As a further improvement of the technical scheme, the lining types adopted in the construction of the III-level surrounding rock comprise FS I P-III Pa lining and FS II P-III Pa lining; the lining types adopted in the IV-level surrounding rock construction comprise an FS I Pjs-IV Ma lining, an FS I P-IV Pa lining and an FS II P-IV Pa lining; the lining types adopted in the construction of the surrounding rock at the V level comprise an FS II P-VMA lining and an FS I P-VMA lining;

the construction section to same country rock rank and lining cutting type in the cross tunnel adopts the same blasting scheme to carry out blasting construction, the blasting scheme includes: the method comprises the following steps of arrangement of blast holes on a tunnel face, circulating depth of advance, size of the blast holes, type of blast hole cutting, explosive loading amount, pitch and row spacing of the blast holes and an explosive loading structure.

As a further improvement of the technical scheme, in the construction of jacking the transverse tunnel into the main tunnel, the initial position of jacking and excavating the arch crown of the transverse tunnel is determined according to the elevation difference between the transverse tunnel and the main tunnel, and the jacking gradient of the arch crown of the transverse tunnel is controlled to be not more than 17 degrees.

As a further improvement of the technical scheme, a reinforcing ring is arranged at the joint position of the transverse hole and the main hole, an auxiliary steel frame is arranged in the reinforcing ring, a door-shaped steel frame is arranged on one side, close to the main hole, of the reinforcing ring, the door-shaped steel frame is connected with the auxiliary steel frame in a segmented mode, adjacent auxiliary steel frames and door-shaped steel frames are connected through longitudinal steel bars, and the distance between the longitudinal steel bars is not more than 1m;

the door type steelframe includes crossbeam and stand, has the space in upper portion both sides position between door type steelframe and the supplementary shaped steel steelframe, is located that the space position sets up stand bracing structure between door type steelframe and the supplementary shaped steel steelframe respectively, and it is closely knit to backfill at door type steelframe, supplementary shaped steel steelframe installation back injection concrete in this space.

As a further improvement to the technical scheme, the shed frame adopts the structural steel supports which are sequentially arranged at intervals along the construction direction of the transverse holes, the distance between the structural steel supports is not more than 100cm, a plurality of locking pin anchor pipes are arranged at the pin position of each structural steel support, the locking pin anchor pipes at the position are arranged in an inclined manner downwards, the included angle between the locking pin anchor pipe close to the horizontal plane and the horizontal plane is 20-30 degrees, and the included angle between the adjacent locking pin anchor pipes is 20-30 degrees;

after the shed frame construction is completed, a concrete layer is sprayed on the inner side of the shed frame, and a main tunnel primary support steel frame structure is constructed, one side of the main tunnel primary support steel frame structure is arranged on a cross beam of a portal steel frame on the outer side of a cross tunnel reinforcing ring, the other side of the main tunnel primary support steel frame structure is arranged on a concrete cushion block, and two locking anchor pipes are respectively constructed at the joints and the arch springing of the main tunnel primary support steel frame structure.

In the advanced support construction step, an advanced long pipe shed support mode is adopted at the hole opening section, and an advanced middle pipe shed and single-layer small pipe support mode is adopted at the hole body section.

As a further improvement of the technical scheme, the water prevention and drainage construction in the transverse tunnel comprises the steps of construction joint water stop belt construction, geotextile and waterproof coiled material construction, waterproof coating spraying construction, drainage blind pipe construction and vault waterproofing construction;

in the vault waterproofing construction step, a grouting pipe and an exhaust pipe are longitudinally pre-buried in the vault before concrete is poured into the lining, lining vault filling grouting is carried out before the circular secondary lining concrete is demolded, grouting is stopped after the grouting reaches design final pressure or the exhaust pipe is discharged, and a grouting hole is tightly sealed and filled after the grouting is finished; the grouting mortar adopts micro-expansive cement mortar, the grouting sequence is from the downhill direction to the uphill direction, and the grouting pressure is not more than 0.2Mpa.

As a further improvement of the technical scheme, the main tunnel comprises a main tunnel left line and a main tunnel right line which are parallel, small-distance blasting construction is controlled in a small-mileage section in the main tunnel construction, the main tunnel left line and the main tunnel right line are alternately constructed, sandbags are backfilled to the maximum span to reduce the influence of vibration on the tunnel in the blasting construction process, and the vibration speed of blasting particles is controlled at 10cm/s.

Compared with the prior art, the invention has the following beneficial effects:

the method combines the construction conditions and the topographic features of the plateau area, optimizes the construction process flow and the key process steps in the construction process, well ensures the safety and the construction quality in the construction process, meets the requirement on the construction progress, and obtains good economic benefit and social benefit in the tunnel construction application of the plateau area.

Constructing by adopting different construction modes according to different surrounding rock grades, and constructing the transverse tunnel in sections according to the adopted construction mode, the surrounding rock grade and the lining type to formulate a corresponding construction scheme; and the limit brought to mechanized drilling and blasting construction by the limited construction space in the tunnel in the construction process of the transverse tunnel is combined, the point position of the blast hole in the construction blasting scheme is set, the mechanized drilling and blasting operation can play a role to the maximum extent, the quality of the light blasting in the tunnel is ensured, the construction efficiency is improved, the construction effect is ensured, and the safety of the construction process is well ensured.

Through optimizing the transverse hole forward hole top-raising construction process, the construction safety and operability in the whole construction process of the joint part are ensured, and under the condition of the integral structural strength of the joint part, the problem caused by over-support in the transverse hole forward hole top-raising construction process is well solved, the construction work amount is reduced, the construction period is ensured, and the subsequent forward hole construction operation is facilitated

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and it is obvious for those skilled in the art that other related drawings can be obtained according to these drawings without inventive efforts.

Fig. 1 is a schematic view of a tunnel construction structure according to the present invention.

Fig. 2 is a schematic view of the supporting structure of the long pipe shed in advance at the entrance of the transverse tunnel in tunnel construction.

FIG. 3 is a schematic diagram of a grouting guide pipe structure for a cross tunnel portal section advanced long pipe shed support in tunnel construction.

Fig. 4 is a schematic view of a pipe shed support structure in advance in tunnel construction.

Fig. 5 is a schematic view of the arrangement of the pipe shed supporting structure in the longitudinal direction in advance in tunnel construction.

Fig. 6 is a schematic view showing the arrangement of the advanced small duct support structure in the longitudinal direction in tunnel construction according to the present invention.

FIG. 7 is a schematic cross-sectional view of a micro-step method construction process in tunnel construction according to the present invention.

FIG. 8 is a schematic longitudinal section of a micro-step method construction process in tunnel construction according to the present invention.

FIG. 9 is a schematic cross-sectional view of a full-section method construction process in tunnel construction according to the present invention.

FIG. 10 is a schematic longitudinal sectional view of a full-section method of the present invention in tunnel construction.

FIG. 11 is a schematic cross-sectional view of a step construction process in tunnel construction according to the present invention.

FIG. 12 is a schematic longitudinal sectional view of a step construction process in tunnel construction according to the present invention.

FIG. 13 is a structural diagram of arrangement of blast holes of class III surrounding rock FS I P-III Pa lining type tunnel face in tunnel construction.

FIG. 14 is a schematic diagram of different blast hole locations of class III wall rock FS I P-III Pa lining type tunnel face in tunnel construction.

FIG. 15 is a structural diagram of arrangement of blastholes of a FS IIP-III Pa lining type tunnel face in class III surrounding rocks in tunnel construction.

FIG. 16 is a schematic diagram of different blast hole locations of class III wall rock FS IIP-III Pa lining type tunnel face in tunnel construction.

FIG. 17 is a structural diagram of arrangement of blast holes on a tunnel face when a wedge undermining construction mode is adopted for the lining type FS I Pjs-IV Ma in IV-level surrounding rock in tunnel construction.

FIG. 18 is a schematic diagram of different blast hole locations on a tunnel face when a wedge undermining construction mode is adopted for the lining type FS I Pjs-IV Ma in IV-level surrounding rock in tunnel construction.

FIG. 19 is a structural diagram of arrangement of blast holes on a tunnel face when a straight-hole undermining construction mode is adopted for the FS I Pjs-IV Ma lining type in IV-level surrounding rock in tunnel construction.

FIG. 20 is a schematic diagram showing different blast hole locations on a tunnel face when a straight-hole undermining construction mode is adopted for the FS I Pjs-IVMa lining type in IV-level surrounding rock in tunnel construction.

FIG. 21 is a structural diagram of arrangement of tunnel face blast holes in the FS I P-IV Pa lining type in IV-level surrounding rocks in tunnel construction when a wedge cut construction mode is adopted.

FIG. 22 is a schematic diagram of arrangement of different blast hole sites on a tunnel face when a wedge cut construction mode is adopted for FS IP-IV Pa lining type in IV-level surrounding rocks in tunnel construction.

FIG. 23 is a structural view of arrangement of tunnel face blast holes in the FS I P-IV Pa lining type in IV-level surrounding rock in tunnel construction when a straight-hole undermining construction mode is adopted.

FIG. 24 is a schematic diagram of arrangement of different blast hole sites on a tunnel face when a straight-hole undermining construction mode is adopted for FS IP-IV Pa lining type in IV-level surrounding rocks in tunnel construction.

FIG. 25 is a structural diagram of arrangement of blasting holes on a tunnel face when a wedge cut construction mode is adopted for FS IIP-IV Pa lining type in IV-level surrounding rocks in tunnel construction.

FIG. 26 is a schematic diagram of arrangement of different blast hole sites on a tunnel face when a wedge cut construction mode is adopted for FS IIP-IV Pa lining type in IV-level surrounding rocks in tunnel construction.

FIG. 27 is a structural view of arrangement of tunnel face blast holes in the FS IIP-IV Pa lining type in IV-level surrounding rock in tunnel construction when a straight-hole undermining construction mode is adopted.

FIG. 28 is a schematic diagram of the arrangement of different blast hole sites on the tunnel face when the straight-hole undermining construction mode is adopted for the FS IIP-IV Pa lining type in IV-level surrounding rock in tunnel construction.

FIG. 29 is a structural view of arrangement of blast holes of a V-level surrounding rock FS IIP-VMa lining type tunnel face in tunnel construction.

FIG. 30 is a schematic diagram of different blast hole locations of a V-level surrounding rock FS IIP-VMa lining type tunnel face in tunnel construction.

Fig. 31 is a structural view of arrangement of blast holes of a v-level surrounding rock FS I P-VMa lining type tunnel face in tunnel construction.

FIG. 32 is a schematic diagram of a construction structure for horizontal-to-vertical-tunnel top-lifting in tunnel construction according to the present invention.

Fig. 33 is a schematic view of a construction structure of the transverse-cavity raised arch top in the tunnel construction of the present invention.

FIG. 34 is a schematic view of a shed tunnel construction structure in a main tunnel in tunnel construction according to the present invention.

FIG. 35 is a schematic diagram of a main tunnel excavation structure in tunnel construction according to the present invention.

FIG. 36 is a schematic view of the structure in the direction I-I in FIG. 32.

FIG. 37 is a cross-sectional view of a junction between a lateral hole and a main hole in tunnel construction according to the present invention.

FIG. 38 is a schematic view of the canopy frame of FIG. 32 in the direction II-II.

Wherein: 11. transverse holes 12, main holes 13 and shed holes;

21. the support steel frame 22, the reinforcing ring 23, the auxiliary steel frame 24, the portal steel frame 25, the column diagonal bracing structural member 26, the steel frame 27, the top steel frame beam 28, the guide pipe 29 and the main hole primary support steel frame structure;

31. a concrete pad.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.

The tunnel transverse hole is positioned on one side of the advancing direction of the tunnel route, and a certain inclination angle is formed between the tunnel transverse hole and the main hole. Because the plateau of department, the air is thin, the atmospheric pressure is low, the weather is cold, the very big influence that the condition such as oxygen deficiency all brought to tunnel construction operation specifically embodies: for example, the size of the transverse hole is smaller than that of the main hole in the construction process of the transverse hole, the operation space of the construction adopting mechanical drilling and blasting in the transverse hole is greatly limited, and how to reasonably arrange the blast holes in the blasting design and the forming quality of the blast holes in the operation process need to be considered on the premise of ensuring the normal operation of the mechanical drilling and blasting operation. Although the mode of combining the transverse hole and the main hole for construction can be convenient for the construction of the main hole of the tunnel to a certain extent, the stress state at the joint of the transverse hole and the main hole is complex, and the structure is also a weak position in tunnel engineering, so that great potential safety hazards exist in the construction process, and great difficulty is brought to the whole construction of the tunnel.

The existing problems all bring different degrees of influence to the construction of the tunnel, so the problems need to be fully considered in the process of formulating the tunnel construction scheme.

Based on the above consideration, the construction method adopted in the embodiment is a construction method of constructing a transverse hole first and then constructing a main hole, as shown in fig. 1, the specific construction steps are as follows:

1. construction of transverse holes

1. Advanced support construction

The construction of the tunnel cross tunnel adopts advance support construction, the tunnel opening section adopts an advance long pipe shed support mode, and the tunnel body section adopts an advance medium pipe shed and single-layer small pipe support mode.

1.1 ultra-long pipe shed support

Referring to fig. 2, a schematic diagram of a supporting structure of a cross tunnel portal section advanced long pipe shed is shown; the hole opening adopts a 30m D89 pipe shed and a D42 small pipe advance pre-reinforcing measure.

D89 pipe shed hoop interval is 40cm, and the range of setting is in the 120 scope of tunnel hunch portion.

In order to ensure the construction precision of the ultralong pipe shed support in the supporting direction and angle, a pipe shed guide wall is arranged, the pipe shed guide wall is made of C25 concrete, the section size is 1m multiplied by 1m, and the arch part is arranged within 120 degrees. The pipe shed guide wall is provided with 2I 20a light I-shaped steel frames, the outer edges of the steel frames are provided with guide steel pipes with the diameter of 140mm multiplied by 5mm, and the guide steel pipes are welded with the steel frames. Each unit of the steel frame is formed by welding connecting plates, and the units are connected by bolts. When the pipe roof guide wall is constructed, the guide wall is excavated firstly, the outer soil body is encircled by the guide wall, and the inner soil body is not excavated and is used as a support body of the guide wall.

The arch part of the tunnel portal section of the transverse tunnel is provided with a ring of 30m long D89 pipe sheds and D42 small guide pipes for pre-reinforcement, the circumferential distance of the D89 pipe sheds is set to be 40cm, and the longitudinal distance of the small guide pipes in advance is set to be 2m. Setting the basement rock section of the pipe shed to be 1-3 degrees, and setting the external insertion angle of the soil section to be 0-1 degree; the lap length of the inter-cycle forepoling measure is not less than 3m.

The body section phi 89 long shed adopts a hot-rolled seamless steel pipe and a steel flower pipe, the diameter is 89mm, and the wall thickness is 5mm. Two sections of each section of steel pipe are preprocessed into external screw threads, and the number of joints in the same section cannot exceed 50% of the total number of the steel pipes. And two ends of each section of steel pipe are preprocessed into outer screw threads so as to be connected with joint steel pipes, and each section of steel pipe is 4-6m long.

In order to improve the bending resistance of the steel perforated pipe, a steel reinforcement cage can be arranged in the steel perforated pipe, the steel reinforcement cage consists of four main reinforcements and a fixing ring, the diameter of each main reinforcement is phi 18, the fixing ring adopts phi 32 short pipe joints, the wall thickness is 3.5mm, the joint length is 3-5cm, the fixing ring and the main reinforcements are welded, and the fixing ring is arranged at intervals of 1m; as shown in fig. 3.

Grouting a pipe shed; drilling grouting holes on the steel perforated pipe, wherein the hole diameter is 10-16 mm, the hole spacing is 15-20 cm, the steel perforated pipe is arranged in a quincunx shape, and a grout stopping section which is not less than 1m and does not drill holes is reserved at the tail part of the steel perforated pipe; the grouting material adopts cement slurry and cement mortar, when surrounding rock is broken, a part of the grouting material can adopt cement-water glass double-liquid slurry, the strength grade of the slurry is not less than M10, and the grouting pressure is 0.5-2 Mpa; the grouting amount is not less than 80% of the designed grouting amount; and after grouting, performing full-hole plugging by using M10 cement mortar in time. The grouting sequence is from bottom to top, the slurry is diluted and then concentrated, the grouting amount is large and then small, and the grouting pressure is from small to large; when the serial grouting occurs, adopting separate grouting to build porous grouting or blocking serial grouting holes to separate the grouting; when the grout inlet amount is large and the pressure is not changed, the grout concentration and the mix proportion are adjusted, the gelling time is shortened, and low-flow low-pressure grouting or intermittent grouting is adopted.

The long pipe shed is constructed by adopting a jacking method, after the opening is excavated, a pipe shed guide wall and guide steel pipes are constructed in time, the angle of each guide pipe is 1-3 degrees, the drilling precision of the long pipe shed is ensured, the long pipe shed is prevented from intruding into a tunnel excavation line or adjacent pipes are crossed at one position, and the pipe distance, the inclination angle and the construction error of the steel pipes of the long pipe shed are ensured to meet the design requirements.

The construction sequence of the pipe shed is from top to bottom, drilling construction is carried out by adopting a jump beating mode according to hole site numbers of measurement lofting, steel flower pipes are timely jacked after each hole is drilled, and the steel reinforcement cage is jacked into the steel pipes after the pipe shed is completely jacked.

1.2 leading middle pipe shed support

In order to ensure the self-stability of the tunnel body section of the cross tunnel, the tunnel cross tunnel is provided with an advanced middle pipe shed, and a schematic diagram of a supporting structure of the advanced middle pipe shed is shown in fig. 4.

The arch part of the transverse tunnel is provided with a ring of 6-10m medium pipe sheds, the medium pipe sheds are made of steel pipes with the diameter of phi 60mm multiplied by 5mm, the circumferential distance is set to be 0.4m, the outer inserting feet are not more than 10 degrees, and the lap joint distance between the two groups of medium pipe sheds is not less than 3m. Fig. 5 is a schematic view showing the arrangement of the leading-middle pipe shed supporting structure in the longitudinal direction.

The medium pipe shed is made of hot rolled seamless steel pipe, the pipe wall is drilled and grouted, the aperture is 8-10mm, the hole spacing is 10-20cm, the medium pipe shed is arranged in a quincunx shape, the front end is processed into a cone shape, the tail length is not less than 30cm, and the medium pipe shed is used as a grout stopping section without drilling. The grouting pressure is generally 0.5-1.0MPa.

1.3 advanced small duct support

D42 small guide pipes are D42 seamless hot-rolled steel pipes, are 4m long, 40cm in circumferential distance and 2m in longitudinal distance, and are filled with single cement slurry. Drilling grouting holes at the front part, wherein the hole diameter is 6-8mm, the hole spacing is 10 and 20cm, the grouting holes are arranged in a quincunx shape, the front end is processed into a cone shape, the tail part length is not less than 30cm, and the grouting holes are used as grout stopping sections without drilling. The grouting pressure is generally not more than 1MPa, and the concrete slurry mixing proportion and the grouting pressure are determined by field experiments.

The advanced small guide pipe is matched with a section steel frame (a grid steel frame) for use, and the longitudinal lap joint length of the advanced small guide pipe is not less than 1m. The advanced small duct grouting pressure is low, the length is short, and the calculation is carried out according to the diffusion radius of a single hole. The external insertion angle is set to be 10-15 degrees and can be adjusted according to actual conditions; the arrangement thereof is as described in FIG. 6.

2. Tunnel excavation construction

Adopt different construction methods to be under construction to different country rock grades, include: and constructing the surrounding rock sections of the III level and the IV level by adopting a full-section method, and constructing the surrounding rock sections of the V level by adopting a micro-step method.

2.1 micro-step method construction

FIG. 7 is a schematic cross-sectional view of a micro-step method construction process, and FIG. 8 is a schematic longitudinal-sectional view of the micro-step method construction process; the construction process of the I-type V-level surrounding rock of the double lanes of the tunnel is as follows:

the face is divided into a part (1) and a part (2), the part (2) is a micro-step which lags behind the part (1) by 3-5m, after the micro-step is formed by construction excavation, the part (1) and the part (2) are excavated at the same time, and concrete spraying sealing or anchor rod grouting reinforcement is adopted when the face is unstable according to the revealing condition of the face excavation;

constructing primary supports at the periphery of the step of the circulation part (1) and the previous circulation part (2), and arranging a base plate when a system anchor rod is installed, wherein the base plate is closely attached to a base surface;

after the part lags behind the part (2) for a certain distance, the part (3) filled with the hole slag is used as a construction platform;

after a distance lags behind the part (3), removing the part (4) from backfilling;

pouring an inverted arch and a side wall foundation of the V part, wherein the inverted arch requires the whole pouring;

pouring an inverted arch filling VI part to the design height after the inverted arch concrete is finally solidified;

and cleaning the primary support base surface, constructing a water-proof and drainage project, and performing analysis according to the monitoring and measuring result, and pouring VII-part lining once by using the lining template trolley after the surrounding rock and the primary support are deformed stably.

When the micro-step method is used for excavating, the explosive quantity of one-time simultaneous detonation is controlled, and the influence of blasting vibration on surrounding rocks is reduced. And the V-level surrounding rock is reinforced by adopting advanced pipe shed high-pressure grouting, the grouting pressure is 0.5-2MPa, and the specific grouting pressure is determined by field tests. During excavation, the drilling depth is strictly controlled, and a certain slope can be reserved on the face, so that the face is prevented from being hung upside down. After blasting, the concrete is sprayed primarily to seal the surrounding rock in time, and before primary spraying, a wet spraying trolley can be adopted to perform blowing and dust removal on the surface of the surrounding rock, so that the primary spraying sealing effect is ensured. The primary support should be closed into a ring as soon as possible. When the micro-step method is used for construction, the upper step and the lower step are drilled and detonated simultaneously, and supporting operation is carried out in parallel.

2.2 full-section construction

FIG. 9 is a schematic cross-sectional view of a construction process by a full cross-section method, and FIG. 10 is a schematic longitudinal cross-sectional view of the construction process by the full cross-section method; the tunnel surrounding rock construction process is as follows:

excavating a part (1); constructing primary support around the part (1); the system anchor rod is required to be provided with a base plate, and the base plate is closely attached to the base surface;

after the part lags behind the part (1) for a certain distance, the part (2) filled with the hole slag is used as a construction platform;

after lagging behind part (2) for a certain distance, removing the hole slag in the range of part (3);

pouring an IV part of inverted arch on a side wall foundation, wherein the inverted arch requires whole pouring;

after the inverted arch concrete is finally set, pouring an inverted arch filling V part to the designed height;

and cleaning a primary support base surface, constructing a waterproof and drainage project, analyzing according to a monitoring and measuring result, and pouring the VI part lining (arch wall lining is constructed once) by using the lining template trolley once after the surrounding rock and the primary support are deformed stably.

2.3 step construction

FIG. 11 is a schematic cross-sectional view of a step construction process, and FIG. 12 is a schematic longitudinal-sectional view of the step construction process; the tunnel two-lane II-type V-level surrounding rock construction process comprises the following steps:

excavating a part (1); constructing primary supports around the step of the part (1), wherein a base plate must be arranged when a system anchor rod is installed, and the base plate is closely attached to a base surface to construct the next circulation advance support;

after delaying a distance from the part (1), excavating the part (2); constructing primary support around the step of the part (2); when the system anchor rod is installed, a base plate is required to be arranged and is closely attached to a base surface;

after a distance lags behind the part (2), excavating the part (3); constructing a tunnel bottom primary support;

according to the analysis of the monitoring measurement result, after the primary support is converged, the inverted arch and the side wall foundation of the part (4) are poured, wherein the inverted arch requires the whole pouring;

pouring an inverted arch filling part (5) after the inverted arch concrete is finally set;

and cleaning the primary support base surface and constructing a waterproof and drainage project. And (4) according to the analysis of the monitoring and measuring result, after the deformation of the surrounding rock and the primary support is stable, pouring (6) part of lining (arch wall lining is constructed at one time) by using the lining template trolley at one time.

3. Blasting construction

And surrounding rocks of III, IV and V levels of the tunnel are excavated by smooth blasting, the loading amount is strictly controlled, construction is designed according to the smooth blasting, the disturbance of blasting waves to the surrounding rocks is reduced, and the purpose of protecting the surrounding rocks is achieved. A three-arm rock drilling trolley is adopted as a main part, a manual pneumatic rock drill is used for drilling holes, and a non-electric millisecond detonator is subjected to differential initiation. The excavating machine adopts a three-arm drill jumbo and a manual pneumatic rock drill (YT-28 type air gun) to assist in drilling, and adopts a phi 42 drill bit to drill holes.

Smooth blasting is influenced by various factors, including geological factors such as surrounding rock strength, integrity, joints, bedding and the like, the geological structure of the surrounding rock on site is diversified, and blasting parameters are dynamically adjusted through site design. The technical parameters obtained by pilot blasting of the same type of surrounding rock are used as a preliminary basis, each cycle of blasting operation is properly adjusted according to the blasting effect of the previous cycle and the characteristics of the surrounding rock of the cycle, and a group of optimal technical parameters is selected, wherein the previous cycle is the pre-design and pilot blasting of the next cycle.

The smooth blasting resistance line is the thickness of a circle of rock between the peripheral hole and the outermost auxiliary hole. It is often expressed by a density coefficient K (K = E/W) of peripheral eyes, and its size has a great influence on smooth blasting. Both theory and practice prove that the blasting effect is good when the density coefficient K of the peripheral holes is 0.8.

W = E/K from K = E/W, and when K =0.8, W =1.25E;

in the formula: w-line of resistance, cm; e-peripheral eye spacing, cm.

The design parameters for the smoothwall blasting are shown in the following table:

in the project cross tunnel construction, due to the complex topography, landform and environment, the geological conditions of surrounding rocks of a construction section are complex, including surrounding rocks of different grades of III, IV and V; constructing by adopting different construction modes according to different surrounding rock levels, wherein a full-section method is adopted for constructing the surrounding rock sections of level III and level IV, and a micro-step method is adopted for constructing the surrounding rock section of level V; then, segmenting each construction section of the cross tunnel according to the adopted construction mode, the surrounding rock grade and the lining type, classifying each section of the cross tunnel according to the adopted construction mode, the surrounding rock grade and the lining type, and generating a corresponding blasting construction scheme according to the characteristic attributes (including the construction mode, the surrounding rock grade, the lining type, the cross tunnel parameter and the like) of each section of the cross tunnel under different classifications, wherein the blasting construction scheme comprises the arrangement of holes on a tunnel face, the circulating depth, the size of a blast hole, the type of a blast hole cut, the explosive loading amount, the hole pitch and the row pitch of the blast hole, a loading structure, blasting control and the like; and then blasting construction is carried out on each section of the transverse hole according to the generated blasting scheme.

The surrounding rock grade, lining type and construction method adopted by the cross tunnel construction project in segmented construction are specifically shown in the following table:

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the blast hole drilling construction adopts three-arm rock drilling trolley equipment, the hole diameter of the drill hole is 38-42mm, and the actual designed hole diameter is 41mm. The diameter of the adopted medicated roll is 32mm, the length is 20cm and 30cm, and the weight is 200g and 300g.

According to the construction characteristics and the construction experience, the blasting adopts a wedge-shaped cut or a straight-hole cut, and the periphery adopts smooth blasting.

In the blasting construction scheme specifically adopted for the project:

aiming at class III surrounding rock, a wedge-shaped cut construction mode is adopted, the circular footage is designed to be 3.0m, peripheral holes are not ultra-deep, cut holes are ultra-deep by 0.4m, and auxiliary Kong Chaoshen 0.2.2 m. Namely, the depth of the peripheral holes is 3.0m, the depth of the cut holes is 3.4m, and the depth of the auxiliary holes is 3.2m.

Aiming at IV-level surrounding rocks, a wedge-shaped cut construction mode or a straight-hole cut construction mode can be adopted; when a wedge-shaped cut mode is adopted, the circular footage is designed to be 2.4m, peripheral holes are not ultra-deep, cut holes are ultra-deep by 0.4m, and auxiliary Kong Chaoshen 0.2.2 m; when a straight-hole cutting mode is adopted, the circular footage is designed to be 2.4m, peripheral holes are not ultra-deep, cut holes are ultra-deep by 0.4m, auxiliary Kong Chaoshen 0.2.2 m and crushing Kong Chaoshen 0.2.2 m; namely, the depth of the peripheral holes is 2.4m, the depth of the undercut holes is 2.8m, and the depth of the auxiliary holes is 2.6m.

A straight-hole cut construction mode is adopted for V-level surrounding rock, a circular footage is designed to be 1.0m, peripheral holes are not ultra-deep, cut holes are ultra-deep by 0.2m, and auxiliary Kong Chaoshen 0.2.2 m. Namely, the depth of the peripheral holes is 1.0m, the depth of the undercut holes is 1.2m, and the depth of the auxiliary holes is 1.2m.

The blasting construction aims at different surrounding rock grades and lining types, and the adopted cyclic footage is shown in the following table:

during blasting construction, the explosive consumption of a unit rock mass not only affects the rock breaking block degree, the rock flying distance and the blasting pile shape, but also affects the blast hole utilization rate, the drilling workload, the labor productivity, the material consumption, the tunneling cost, the section profile quality and the stability of surrounding rocks. The unit consumption of the reasonably designed explosive is often dependent on various factors, including the physical and mechanical properties of the rock, the fracture surface, the explosive property, the diameter and the depth of a blast hole and the like.

Wherein, the design aiming at the medicine loading amount is as follows:

the calculation of the charging amount of the smooth blasting is mainly to determine the charging concentration of the blast holes of the smooth blasting layer of the peripheral hole, namely expressed in kg/m, and the charging concentration is obtained by adopting a test method or selected from the similar projects:

q＝QEV

in the formula:

q-charge concentration, kg/m;

q-consumption per unit volume, g/m ³ ；

E-peripheral eye spacing, m;

v- -minimum line of resistance, m;

and checking data through field tests and construction calendars by using an algorithm, and determining that q =0.07-0.15kg/m. Calculated according to q =0.15 kg/m.

The design for the number of blastholes is as follows:

N＝Q S/ηy

in the formula:

n is the number of blastholes, excluding unfilled holes;

q-powder factor, generally Q =1.2-2.4kg/m ³ ；

S-area of excavation section, m ³ ；

Eta, the charge coefficient, namely the ratio of the charge length to the blast hole length, is temporarily taken to be 0.7;

y is the mass of explosive per meter of cartridge, kg/m, such as rock emulsion explosive No. 2 y =0.91.

In the blasting construction scheme, the arrangement of the tunnel face blast holes comprises:

aiming at class III surrounding rock, the pitch of peripheral holes is designed to be 50cm, the minimum resistance line of the peripheral holes is designed to be 60cm, other tunneling Kong Kongju are designed to be 50cm, the row spacing between the tunneling holes is designed to be 70cm, the hole pitch of a bottom plate hole is designed to be 80cm, and the row spacing between the bottom plate hole and a blast hole positioned on the upper side of the bottom plate hole is designed to be 80cm.

Referring to fig. 13 and 14, for the FS iP-III Pa lining type in class III surrounding rock:

the blast hole site is symmetrical the setting relative to its central line on the face of a palm, and the blast hole site is arranged including: 10 cut holes arranged in a row; the auxiliary cut holes are arranged on the outer sides of the cut holes, the distance between the cut holes is 50cm, the distance between the cut holes and the center line is 1.4m, and the row distance between the cut holes and the auxiliary cut is 30cm; the tunneling holes comprise 3 first tunneling holes horizontally arranged above the cut holes, 6 second tunneling holes arranged on the two outer sides of the cut holes and 6 third tunneling holes arranged above the cut holes in an arc shape; the 16 bottom plate holes are horizontally arranged in two rows at the bottom of the palm surface; the auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the peripheral holes are uniformly distributed at the outer side of the auxiliary hole along the circumferential direction of the tunnel face by 35 peripheral holes.

As shown in fig. 14, the inclination angle of the cut hole is set to 70 °, the inclination angle of the auxiliary cut is set to 85 °, and the other blast holes are set to 90 °.

The explosive concentration in the cut hole is 0.65kg/m, the explosive concentration in the auxiliary cut is 0.55kg/m, the explosive concentration of the driving hole is 0.5kg/m, the explosive concentration of the bottom plate hole is 0.6kg/m, the explosive concentration of the auxiliary hole is 0.55kg/m, and the explosive concentration of the peripheral hole is 0.2kg/m.

The specific blast hole arrangement and blasting parameters used are shown in the following table:

referring to FIGS. 15 and 16, for the FS IIP-III Pa lining type in class III surrounding rock:

the blast hole sites are symmetrically arranged on the tunnel face relative to the center line; the arrangement of blast hole positions comprises: 10 cut holes arranged in a row; 10 auxiliary cut holes are arranged on the outer sides of the cut holes, and the row distance between each cut hole and each auxiliary cut hole is not more than 30cm; the tunneling holes comprise 3 first tunneling holes horizontally arranged above the cut holes, 6 second tunneling holes arranged on two outer sides of the auxiliary cut and 7 third tunneling holes arranged above the cut in an arc shape; the 16 bottom plate holes are horizontally arranged in two rows at the bottom of the palm surface; the 18 auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the peripheral holes are uniformly distributed at the outer side of the auxiliary hole along the circumferential direction of the tunnel face.

The inclination angle of the cut hole is set to be 65-70 degrees, the inclination angle of the auxiliary cut is set to be 70-76 degrees, and the inclination angle of the tunneling hole is set to be 80-85 degrees.

aiming at IV-grade surrounding rock, when a wedge-shaped cut construction mode is adopted, the hole pitch of peripheral holes is designed to be 50cm, the minimum resistance line of the peripheral holes is designed to be 60cm, other tunneling Kong Kongju are designed to be 50cm, the row pitch between tunneling holes is designed to be 80cm, the hole pitch of a bottom plate is 80-100cm, and the row pitch between the bottom plate hole and a blast hole positioned on the upper side of the bottom plate hole is designed to be 80cm.

When a straight-hole undermining construction mode is adopted, the hole pitch of the peripheral holes is designed to be 50cm, the minimum resistance line of the peripheral holes is designed to be 60cm, other tunneling Kong Kongju are designed to be 50cm, the row pitch between the tunneling holes is designed to be 60cm, the hole pitch of the bottom plate is 80-100cm, and the row pitch between the bottom plate hole and the blast hole positioned on the upper side of the bottom plate hole is set to be 80cm.

Aiming at the lining type of FS I Pjs-IV Ma in IV-grade surrounding rock:

referring to fig. 17 and 18, the blast hole sites are symmetrically arranged on the tunnel face with respect to the center line thereof; when adopting wedge undercutting construction mode, the big gun hole site is arranged including: 10 cut holes arranged in a row; 12 auxiliary cut holes arranged at the outer sides of the cut holes; the tunneling holes comprise 5 first tunneling holes arranged above the cut holes in an arc shape, 10 second tunneling holes arranged on two outer sides of the auxiliary cut holes and 13 third tunneling holes arranged on the outer sides of the first tunneling holes in an arc shape; the bottom plate holes are 20 and are horizontally arranged in two rows at the bottom of the tunnel face; the 17 auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the 37 peripheral holes are uniformly distributed on the outer side of the auxiliary hole along the periphery of the tunnel face.

When adopting wedge undercutting construction mode:

the inclination angle of the cut hole is set to be 70 degrees, the inclination angle of the auxiliary cut is set to be 75 degrees, and the inclination angles of the tunneling holes are sequentially set to be 80 degrees and 85 degrees.

The explosive concentration in the cut hole is 0.65kg/m, the explosive concentration in the auxiliary cut is 0.55kg/m, the explosive concentration of the tunneling hole is 0.5kg/m, the explosive concentration of the bottom plate hole is 0.6kg/m, the explosive concentration of the auxiliary hole is 0.55kg/m, and the explosive concentration of the peripheral hole is 0.2kg/m.

referring to fig. 19 and 20, when the straight-hole undermining construction method is adopted, the blast hole site arrangement includes: 10 cut holes arranged in a row; 10 auxiliary cut holes arranged at the outer sides of the cut holes; the tunneling holes comprise 7 first tunneling holes arranged above the cut holes in an arc shape, 5 second tunneling holes arranged on the inner sides of the first tunneling holes in an arc shape, and 13 third tunneling holes, and the third tunneling holes are respectively arranged between the cut holes and on the outer sides of the auxiliary cut holes; the bottom plate holes, 20 bottom plate holes are horizontally arranged in two rows at the bottom of the palm surface; the 17 auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the 37 peripheral holes are uniformly distributed on the outer side of the auxiliary hole along the periphery of the tunnel face.

When adopting the straight-hole undermining construction mode:

the distance between the cut hole and the center line of the tunnel face is designed to be 1.2m, and the distance between the cut hole and the auxiliary cut is designed to be 1m.

The explosive concentration in the cut hole is 0.65kg/m, the explosive concentration in the auxiliary cut is 0.55kg/m, the explosive concentration in the driving hole is 0.5kg/m, the explosive concentration in the bottom plate hole is 0.6kg/m, the explosive concentration in the auxiliary hole is 0.55kg/m, and the explosive concentration in the peripheral hole is 0.2kg/m.

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aiming at the FS I P-IV Pa lining type in IV-level surrounding rocks:

referring to fig. 21 and 22, the blast hole sites are symmetrically arranged on the tunnel face with respect to the center line thereof; when adopting wedge undercutting construction mode, the big gun hole site is arranged including: 10 cut holes arranged in a row; 20 auxiliary cut grooves which are arranged on the outer sides of the cut holes in two rows; the tunneling eyes comprise 3 first tunneling eyes horizontally arranged above the cut holes, 6 second tunneling eyes arranged on two outer sides of the auxiliary cut holes and 6 third tunneling eyes arranged on the outer sides of the first tunneling eyes in an arc shape; the bottom plate holes are arranged in two rows at the bottom of the tunnel face in 17; the 17 auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the peripheral holes are uniformly distributed at the outer side of the auxiliary hole along the circumferential direction of the tunnel face by 38 peripheral holes.

When adopting wedge undercutting construction mode:

the inclination angle of the cut hole is set to be 70 degrees, the inclination angle of the auxiliary cut is set to be 80 degrees, and the inclination angle of the tunneling eye is sequentially set to be 80 degrees and 85 degrees from inside to outside.

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referring to fig. 23 and 24, when the straight-hole undercutting construction method is employed, the arrangement of blast hole sites includes: 10 cut holes arranged in a row; 20 auxiliary cut grooves which are arranged on the outer sides of the cut holes in two rows; the tunneling eyes comprise 3 first tunneling eyes which are arranged above the cut holes in a horizontal arrangement mode, 6 second tunneling eyes which are arranged on the inner sides of the first tunneling eyes in an arc-shaped arrangement mode, and 6 third tunneling eyes which are arranged on the outer sides of the first tunneling eyes in an arc-shaped arrangement mode; the bottom plate holes are arranged in two rows at the bottom of the tunnel face in 17; the 17 auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the peripheral holes are uniformly distributed at the outer side of the auxiliary hole along the circumferential direction of the tunnel face by 38 peripheral holes.

When adopting the straight hole undermining construction mode:

the distance between each cut hole and the center line of the tunnel face is set to be 0.8m, the distance between each cut hole and each auxiliary cut is set to be 0.6m, and the distance between two rows of auxiliary cuts is set to be 0.8m;

aiming at the FS IIP-IV Pa lining type in IV-level surrounding rock:

as shown in fig. 25 and 26, the blast hole sites are symmetrically arranged on the tunnel face with respect to the center line thereof; when adopting wedge undercutting construction mode, the big gun hole site is arranged including: 14 cut holes arranged in a row; 16 auxiliary cut holes which are arranged in two rows are positioned at the outer sides of the cut holes; the tunneling eyes comprise 3 first tunneling eyes horizontally arranged above the cut holes, 8 second tunneling eyes arranged on two outer sides of the auxiliary cut holes and 7 third tunneling eyes arranged on the outer sides of the first tunneling eyes in an arc shape; the 18 bottom plate holes are horizontally arranged in two rows at the bottom of the palm surface; the auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and the peripheral holes are uniformly distributed at the outer side of the auxiliary hole along the circumferential direction of the tunnel face by 40 peripheral holes.

When adopting wedge undercutting construction mode:

the inclination angle of the cut hole is set to 65 degrees, and the inclination angles of the auxiliary cut holes are set to 73 degrees and 82 degrees from inside to outside in sequence.

as shown in fig. 27 and 28, when the straight-hole undermining construction method is adopted, the arrangement of blast hole sites includes: 14 cut holes arranged in a row; 28 auxiliary cut holes which are arranged at the outer sides of the cut holes in two rows; the tunneling eyes comprise 3 first tunneling eyes which are horizontally arranged above the cut hole, 6 second tunneling eyes which are arranged on the inner sides of the first tunneling eyes in an arc-shaped manner, and 7 third tunneling eyes which are arranged on the outer sides of the first tunneling eyes in an arc-shaped manner; the bottom plate holes are arranged in two rows at the bottom of the tunnel face in 18 manner; the auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face, and the number of the auxiliary holes is 16; and the peripheral holes are uniformly distributed at the outer side of the auxiliary hole along the circumferential direction of the tunnel face by 40 peripheral holes.

When adopting the straight hole undermining construction mode:

the distance between the cut holes and the center line of the tunnel face is 0.8m, the distance between each cut hole and each auxiliary cut is 0.6m, and the distance between each two rows of auxiliary cut is 0.8m.

aiming at V-level surrounding rock, the hole pitch of peripheral holes is designed to be 50cm, the minimum resistant line of the peripheral holes is designed to be 60cm, other tunneling Kong Kongju are designed to be 50cm, the row pitch between the tunneling holes is designed to be 100cm, the hole pitch of a bottom plate hole is designed to be 80cm, and the row pitch between the bottom plate hole and a blast hole positioned on the upper side of the bottom plate hole is designed to be 100cm.

Referring to fig. 29 and 30, for the FS ii P-vma lining type in class v surrounding rock:

blast hole sites are respectively arranged on an upper step and a lower step of the tunnel face, and the blast hole sites on the upper step and the lower step are symmetrically arranged relative to the center line of the tunnel face;

blast holes adopt a straight-hole cutting mode on the upper step, and the arrangement of the blast hole positions comprises: 3 crushing holes arranged on the center line of the tunnel face in a row; 12 cut holes which are arranged in two rows at two sides of the crushing hole; 8 auxiliary undermining grooves which are arranged in two rows are arranged at the outer side of the undermining hole; the tunneling eyes comprise 11 first tunneling eyes arranged above the cut holes and 13 second tunneling eyes arranged outside the first tunneling eyes in an arc shape; 11 bottom plate holes are horizontally arranged at the bottom of the upper step; the 33 peripheral holes are uniformly distributed along the circumference of the tunnel face;

the big gun hole site is arranged including on the lower step: the tunneling eyes comprise 3 first tunneling eyes horizontally arranged above the lower step, 5 second tunneling eyes positioned below the first tunneling eyes, 7 third tunneling eyes positioned below the second tunneling eyes and 12 fourth tunneling eyes arranged outside the third tunneling eyes; the bottom plate holes are 14 and are horizontally arranged at the bottom of the lower step; the peripheral holes are 14 and are uniformly distributed along the circumference of the tunnel face.

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referring to fig. 31, for the type of FS ip-vma lining in class v surrounding rock:

blast holes adopt a straight cut mode on the upper step, and the arrangement of blast hole sites comprises: 3 crushing holes arranged on the center line of the tunnel face in a row; 6 cut holes are arranged outside the crushing holes; the tunneling eyes comprise 9 first tunneling eyes which are respectively arranged at the outer side and the upper side of the cut hole and 11 second tunneling eyes which are arranged at the outer side of the first tunneling eyes in an arc-shaped arrangement; 11 bottom plate holes are horizontally arranged at the bottom of the upper step; the 13 auxiliary holes are uniformly distributed on the outer side of the tunneling hole along the circumferential direction of the tunnel face; and 29 peripheral holes are uniformly distributed on the outer side of the auxiliary hole along the periphery of the tunnel face.

Blast hole site is arranged including on the lower step: the tunneling eyes comprise 3 first tunneling eyes horizontally arranged above the lower step, 5 second tunneling eyes positioned below the first tunneling eyes, 7 third tunneling eyes positioned below the second tunneling eyes and 12 fourth tunneling eyes arranged outside the third tunneling eyes; the bottom plate holes are 9 and are horizontally arranged at the bottom of the lower step; the peripheral holes are 14 and are uniformly distributed along the periphery of the tunnel face.

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adopt two kinds of loaded constitution in succession and interval in the blasting scheme, wherein plain noodles big gun hole adopts in succession or air interval loaded constitution, and other big gun holes adopt in succession loaded constitution.

The concentration of the peripheral hollow charge is 0.2-0.3 kg/m. A continuous explosive loading structure with the diameter of phi 25mm or spaced explosive loading is adopted, namely, an emulsion explosive with the diameter of phi 32mm is cut into two parts serving as small explosive cartridges, the bottom is loaded with enhanced explosive, and an explosive fuse is connected in series to detonate the sectional explosive cartridges.

And (3) carrying out undermining and auxiliary undermining and other blast holes, adopting a continuous non-coupling explosive loading method, carrying out stemming blocking, and adopting emulsion explosive with the diameter phi =32 mm.

When arranging blast holes on the tunnel face, a measurer determines a tunnel central line and an excavation contour line, marks the positions of the blast holes according to a drilling and blasting design drawing, and can drill the holes after the blast holes are inspected to be qualified. In order to reduce the measuring time and improve the measuring precision, a laser guide instrument is arranged in a straight line section. Laser orientation: the polar coordinate APS section detection and the shot hole positioning are used, the shot hole arrangement diagram is input into an instrument according to different surrounding rock section sizes, and the trolley drilling arm drills and controls the direction according to the hole position on the basis of projecting laser and the hole position, so that the drilling quality is ensured. After blasting, inputting corresponding mileage and section, and automatically detecting the over-under excavation of the section by an instrument through light beams and distributing points according to projection.

When the drilling trolley is used for drilling, before drilling operation, the operation area of the trolley arms is defined according to the drilling explosion design, the drilling sequence of each arm is specified, and the operation time, the drilling deflection angle and the insertion angle of the peripheral holes, the bottom plate holes and the cut holes are specified, so that the drilling can be performed orderly without mutual interference. The drilling operation is strictly carried out according to the operation rules, the drilling direction and the drilling position are required to meet the design requirements, and the peripheral hole external insertion angle is accurately controlled.

4. Preliminary bracing construction

The primary support is timely constructed following the excavation surface so as to reduce the exposure time of the surrounding rock, inhibit the deformation of the surrounding rock and prevent the surrounding rock from loosening and peeling in a short period.

Constructing an anchor rod; hard rock and medium hard rock and soil bodies adopt an expansion shell type prestressed hollow anchor rod, the nominal diameter is 25mm, and the nominal wall thickness of the anchor rod body is 5mm. The other sections are suitable for low-prestress resin roll hollow grouting anchor rods. When the anchor is installed upwards, grout is typically fed from the grout pipe and gradually fills the borehole and flows upwards. At the moment, the cavity of the hollow anchor rod body is an exhaust passage, when the air is exhausted, grouting body enters from the tail end of the shell expansion anchor, the cavity is filled with grouting body, the grouting body flows out from the anchor rod head, and grouting is finished. When the anchor rod is installed horizontally or downwards, the hollow anchor rod body is used as a grouting pipe for grouting, and the plastic pipe is used as an exhaust passage. During grouting, slurry is discharged from the bottom of the expansion shell anchoring part, the drill hole channel is gradually filled with the slurry, air is discharged through the exhaust pipe, and when the slurry flows out of the plastic pipe, grouting is completed.

When the side wall anchor rod is used for grouting, the grout outlet of the grouting pipe is inserted into a position 50-100 mm away from the bottom of the hole, grout is continuously poured from bottom to top, and smooth water drainage and air exhaust from the hole are ensured.

The palm surface is closed; the tunnel face is sealed by C25 sprayed concrete with the thickness of 3cm. The upper half part of the tunnel face adopts a phi 25 full-thread glass fiber hollow grouting anchor rod, the standard value of tensile strength is not lower than 600MPa, the elongation at break is not less than 1.5 percent, and the elastic modulus is not lower than 40GPa.

Constructing a reinforcing mesh; the reinforcing mesh and the anchor rod are welded together by spot welding, so that the reinforcing mesh does not shake during spraying. The reinforcing mesh is processed into pieces in a component processing plant, and the holes are welded into a whole.

Concrete spraying construction; the spraying operation is carried out in a segmented and segmented mode, the spraying sequence is from bottom to top, the once spraying thickness is strictly controlled according to a construction technical guideline, when spraying in a layered mode, the next layer is carried out after the concrete of the previous layer is finally set, if spraying is carried out after one hour of final setting, the spraying surface is cleaned by wind and water; the spraying operation follows the excavation working face, and the time from the final setting of the concrete to the next circulating blasting is not less than 3 hours.

5. Water drainage preventing construction for transverse holes

The waterproof concrete structure in the tunnel transverse hole is mainly waterproof, the waterproof of the construction joint and the deformation joint is taken as key points, and the waterproof layer is used for reinforcing the waterproof. The waterproof grade of the lining arch wall of the electromechanical installation section is one grade, the bottom of the auxiliary tunnel is two grades, the waterproof grade of the arch wall of the auxiliary tunnel to be avoided for disaster prevention evacuation rescue is three grades, and the waterproof grade of the rest sections is four grades. The auxiliary tunnel spray anchor lining is mainly suitable for surrounding rock sections which have good integrity and do not have electromechanical equipment and are not avoided, and the waterproof grade design is three-grade waterproof.

The tunnel preliminary bracing and secondary lining between the arch wall lay disconnect-type waterproof layer, disconnect-type waterproof layer by the waterproof board (prevent the drain bar) with geotechnological cloth and form, lay the EVA waterproof board section, the arch wall is laid 1.1m narrow width to the construction joint and is prevented the drain bar, sets up 0.7m narrow width at every board lining cutting middle part arch wall and prevents the drain bar. 1. Laying waterproof boards and geotextiles between the primary support and the secondary lining of the arch wall of the third-level waterproof section; the fourth-stage waterproof section is not provided with an EVA waterproof board and geotextile on the basis of the third-stage waterproof section.

The concrete construction joints poured in the tunnel subsection are divided into a longitudinal construction joint and an annular construction joint. The annular construction joint (primary waterproof section) adopts a composite waterproof structure of a middle-buried self-adhesive rubber water stop belt (S) and a back-pasted self-adhesive rubber water stop belt (S); the annular construction joint (the third-stage waterproof section) adopts a middle-buried self-adhesive rubber water stop belt (S) waterproof structure; the longitudinal construction joint (primary waterproof section) adopts a composite waterproof structure of a middle-buried common steel plate water stop (S) and a cement-based permeable crystalline waterproof material; the longitudinal construction joint (three-level waterproof section) adopts a middle-buried common steel plate water stop belt (S) waterproof structure.

The distance from the buried position of the buried water stop (S) to the back water surface is S1, and the distance from the upstream water surface is S2; when the lining thickness D is less than or equal to 35cm, S1=22cm; when the lining thickness D is more than 35cm, S2=15cm; the radial position of the installation is allowed to deviate +/-2 cm compared with the design, and the longitudinal position of the installation is allowed to deviate +/-3 cm from the center. The water stop belt is accurately embedded, and the middle hollow circular ring is coincided with the deformation joint or the construction joint.

Constructing geotextile and waterproof coiled materials; and laying geotextile and a waterproof board respectively.

Spraying construction of waterproof paint; and spraying a cement-based capillary crystalline waterproof coating on the surface of the concrete.

Construction of a drainage blind pipe; according to the geological and hydrogeological conditions of tunnel engineering, annular and longitudinal blind pipes are arranged at the back of the waterproof layer of the arch wall to form a complete drainage system.

Waterproof construction of the vault; the residual space formed by the fact that concrete is not fully poured is filled through filling and grouting at the back of the tunnel, so that the primary support and the secondary lining close face are stressed together, gaps formed by the fact that concrete is not close or cracked are filled, and the source of underground water is plugged, so that the waterproof effect is achieved.

Longitudinally pre-buried in vault before pouring concrete for lining

A grouting pipe and an exhaust pipe. The lining vault can be filled and grouted before the circular secondary lining concrete is demolded, the grouting pressure is 0.2MPa, M20 cement mortar (micro-expansion cement slurry) is adopted as a grouting material, and grouting can be stopped after the grouting reaches the design final pressure or when the exhaust pipe is discharged. And after grouting, sealing and tightly filling the grouting holes.

The grouting mortar is generally micro-expansive cement mortar, and the mixing proportion of the mortar before construction must be determined after field tests; the grouting sequence is from the downhill direction to the uphill direction, and the grouting pressure is not more than 0.2MPa.

6. Lining construction

In the lining construction of the transverse tunnel, spray anchor lining is adopted for the surrounding rock sections III and IV, and mould lining is adopted for the surrounding rock sections V; the concrete spraying adopts C30 high-strength high-performance concrete.

The secondary lining of the arch wall adopts a full-section integral steel mould lining trolley, a concrete mixing transport vehicle for transportation, pumping concrete for pouring, a vibrator for tamping, and a baffle head mould adopts a steel mould or a wood mould. The concrete pouring needs to be carried out in bilateral symmetry, and the steel mould trolley is prevented from deviating.

2. Transverse hole-to-main hole top-raising construction

When the joint of the transverse hole and the main hole is constructed, the joint of the transverse hole and the main hole has a special structure and a complex stress state, and is also a weak position in the tunnel engineering, so that great potential safety hazards exist in the construction process; usually, in order to guarantee the overall structure intensity of this position department, adopt the construction mode of excessive support to this position usually, adopt this kind of mode though can guarantee security and structural strength in the work progress, but construction process, construction structure are complicated, lead to the construction cycle long to the construction operation is inconvenient.

Referring to fig. 32 to 35, the construction method adopted in the construction step is:

when the transverse tunnel excavation construction is close to the position of the main tunnel, gradually raising the elevation of the transverse tunnel construction vault to the intersection position of the transverse tunnel and the main tunnel;

constructing a shed tunnel from the intersection position of the main tunnel and the crosstunnels along the construction direction of the crosstunnels, entering the main tunnel, excavating the main tunnel in the intersection section of the crosstunnels and the main tunnel, climbing upwards and excavating the shed tunnel from the intersection position of the crosstunnels and the main tunnel to the central line position of the main tunnel, and enabling the height of the shed tunnel to reach the arch crown height of the main tunnel at the central line position of the main tunnel; then continuously excavating the shed tunnel forwards by using the flat slope until the construction reaches the arch springing position of the upper step on the outer side of the main tunnel, and constructing a shed frame in the shed tunnel while constructing the shed tunnel;

and constructing primary support for the upper step of the main tunnel in the shed tunnel, and excavating the main tunnel towards two sides of the main tunnel according to the standard main tunnel section.

The key construction process involved in the embodiment specifically includes:

1. construction of cross section of transverse hole

Aiming at the construction of the cross tunnel cross section, determining the initial position of lifting and excavating the vault of the cross tunnel according to the elevation difference between the cross tunnel and the main tunnel, and controlling the lifting gradient of the vault to be not more than 17 degrees. 10I 16 support steel frames 21 are sequentially arranged at intervals from the starting position of lifting and excavating the transverse holes to the intersection position of the transverse holes and the main hole, and referring to fig. 32, the support steel frames are sequentially erected in the transverse holes according to the central line of the transverse holes.

Referring to fig. 36, when the construction is performed at the junction position between the lateral hole and the main hole, a 0.4m reinforcing ring 22 is provided, 2I 16 (I18) double auxiliary steel frames 23 are provided in the reinforcing ring 22, and 4I 20b double door frames 24 are provided on the reinforcing ring 22 side of the main hole 12. The door-shaped steel frame 24 is connected with the auxiliary steel frame in a welding way. Adjacent auxiliary steel frames 23 and door-shaped steel frames 24 are connected by phi 22 longitudinal steel bars, and the distance between the longitudinal steel bars is 1m. The construction of the reinforcing ring needs to ensure that the reinforcing ring extends into the primary supporting section of the main tunnel, so as to ensure that stable support is provided for the main tunnel support.

The door-shaped steel frame 24 here adopts crossbeam and stand to constitute, forms certain space between door-shaped steel frame and the supplementary shaped steel steelframe in upper portion both sides position, is located that the space position is symmetrical between door-shaped steel frame and the supplementary shaped steel steelframe and sets up stand bracing structure 25, and this stand bracing structure adopts two mutually perpendicular's shaped steel to constitute T shape structure, forms stable connection and support between door-shaped steel frame and the supplementary shaped steel steelframe respectively.

The beam of the portal steel frame 24 is used as a supporting point of the arch centering of the main tunnel, and concrete is sprayed into the gap of the portal steel frame and the auxiliary steel frame after the portal steel frame and the auxiliary steel frame are installed to backfill tightly, so that the stability of the structure is improved. 6-10D 42 lock foot anchor tubes and system anchors are provided on each side of the portal steel frame to further increase the stability of the structure at this location.

And (3) additionally arranging a bottom plate steel frame at a position close to the front hole for 1 arch frame of the primary support of the transverse hole, welding and connecting the front hole arch frame and a cross beam of the door-shaped steel frame at the outermost side of the reinforcing ring, and connecting the front hole inverted arch lining steel bars and the embedded steel bars in the transverse hole inverted arch lining to ensure the strength of the connecting structure at the crossing position of the front hole and the transverse hole, so that the front hole and the transverse hole can play a common stress effect.

2. Shed tunnel excavation construction

Referring to fig. 34, excavating towards the main tunnel along the construction direction of the cross tunnel, excavating the shed tunnel in a climbing or ascending manner from the intersection position of the cross tunnel and the main tunnel to the center line position of the main tunnel, reaching the height same as the height of the main tunnel at the center line position of the main tunnel, and then excavating forwards in a flat slope manner to the arch springing position of the upper step on the outer side of the main tunnel; in the construction process of the shed tunnel, the construction of the shed frame and the temporary support should be carried out simultaneously.

Referring to fig. 38, the canopy frame is made of I16 (I18) type steel supports 26, the type steel supports are sequentially arranged at intervals along the construction direction of the transverse tunnel, the distance between the type steel supports is 100cm, 2D 42 lock pin anchor pipes are arranged at each type steel support pin position, the lock pin anchor pipes are arranged in a downward inclined mode, the included angle between the lock pin anchor pipes close to the horizontal plane and the horizontal plane is set to be 20 degrees, and the included angle between the two lock pin anchor pipes is set to be 20 degrees.

Set up interim supporting construction respectively in the both sides of shaped steel support position, this interim supporting construction includes the interim stock that the interval set up, and interim stock adopts interval 1.0m 1.0 m's plum blossom type to arrange, and interim stock length is 3.0m to spout thickness 25 cm's concrete layer in this position department.

Referring to fig. 37, in the construction of the canopy frame, a top steel frame beam 27 is arranged at the top of the canopy frame along the outer contour line of the primary supporting steel frame structure of the main tunnel, and the top steel frame beam 27 is positioned outside the primary supporting steel frame structure of the main tunnel, so that the top steel frame beam plays a role of supporting, and the top beam steel frame does not need to be taken out again when the arch centering of the main tunnel is constructed in the later process. Correspondingly, the ceiling height of the shed frame shall exceed the design excavation line of the main tunnel during the construction of the shed frame, so as to meet the requirements of temporary support thickness and reserved deformation.

Set up the pipe structure along the outline line interval of top steelframe crossbeam, including a plurality of pipes 28 that the interval set up among the pipe structure, the pipe sets up towards the slope of positive hole bow member top, and the interval of arranging of pipe is 3m, length 4.5m, and the tangent line contained angle of pipe and top steelframe crossbeam outline line sets up to 10.

3. Construction of main tunnel section

And after the shed frame construction is finished, a C25 sprayed concrete layer is constructed on the inner side of the shed frame.

The method is characterized in that a main tunnel primary support steel frame, namely a main tunnel arch frame, is arranged, one side of the main tunnel primary support steel frame structure is welded with a portal steel frame on the outermost side of a reinforcing ring, the other side of the main tunnel primary support steel frame structure is arranged on a concrete cushion block 31, and two anchor pipes with the length of 4m and D42 locking feet are respectively constructed on the sections and the arch feet of the main tunnel primary support steel frame structure.

After the construction of the primary support steel frame structure of the main tunnel in the tunnel is completed, removing the temporary support structure on one side of the tunnel frame and performing pre-support of the step excavation on the main tunnel, closing the tunnel face after the main tunnel is excavated and supported for about 10m, removing the temporary support structure on the other side of the tunnel, performing pre-support of the step excavation on the main tunnel on the other side until the construction space in the main tunnel meets the requirements. At the moment, working faces on two sides in the main tunnel can be constructed simultaneously, and in the process, the closure of the inverted arch in the width range of the transverse tunnel is ensured.

In a ring of secondary lining of the joint of the transverse tunnel and the main tunnel, two settlement joints are respectively arranged on two sides outside the width range of the cross section of the transverse tunnel, so that the problem of cracking of the main tunnel concrete lining at the intersection caused by uneven settlement is solved.

And monitoring the excavation construction process in the whole construction process of the joint position of the transverse hole and the main hole, and adjusting construction and support parameters in time according to monitored data.

And after the positive tunnel intersection section is excavated, the positive tunnel inverted arch and the secondary lining are constructed in time, so that the primary support and the inverted arch form a ring in time, and the overall structural strength and the construction safety are ensured.

Based on the above construction method, one construction structure that can be adopted for the joint between the transverse tunnel and the main tunnel in tunnel construction is as follows, referring to fig. 32, and the construction method includes:

10I 16 supporting steel frames 21 are arranged at intervals from the starting position of the lifting excavation of the transverse hole 11 to the joint position of the transverse hole and the main hole, the supporting steel frames 21 are sequentially erected in the transverse hole according to the deviation of the supporting steel frames from the normal line, the transverse hole at the position is supported, and the height of the supporting steel frames is sequentially increased along with the construction height of the transverse hole.

As shown in fig. 36, a reinforcing ring 22 provided at the junction of the horizontal hole and the vertical hole, 2I 16 (I18) auxiliary steel frames 23 of double-spliced type provided in the reinforcing ring, and 4I 20b double-spliced door-shaped steel frames 24 provided on the side of the reinforcing ring 22 near the vertical hole; 24 merogenesis of door type steelframe and supplementary shaped steel steelframe 23 welded connection, adopt phi 22 longitudinal reinforcement to connect between adjacent supplementary shaped steel steelframe 23, the door type steelframe 24, the interval between the longitudinal reinforcement sets up to 1m.

The portal steel frame 24 comprises a cross beam and an upright post, an upright post inclined strut structural part 25 is arranged at a gap position at two sides of the portal steel frame and the auxiliary steel frame, the upright post inclined strut structural part 25 adopts two mutually vertical section steels to form a T-shaped structure, and stable connection and support are respectively formed between the portal steel frame and the auxiliary section steel frame; 6-10D 42 lock anchor pipes and system anchor rods are respectively arranged on two sides of the portal steel frame.

The shed tunnel supporting structure arranged in the main tunnel comprises a plurality of profile steel supports 26 which are sequentially arranged at intervals along the construction direction of the transverse tunnel, and the profile steel supports form a shed frame for supporting the shed tunnel. The height of the section steel support is gradually increased from the position of the reinforcing ring to the position of the center line of the main tunnel, the elevation of the section steel support is the same as that of the center line of the main tunnel at the position of the center line of the main tunnel, and the elevation of the section steel support is the same as that of the center line of the main tunnel from the position of the center line of the main tunnel to the position of an upper step arch foot on the outer side of the main tunnel. The distance between the section steel brackets 26 is set to be 100cm; the position of the section steel support foot is provided with two foot locking anchor pipes respectively, the foot locking anchor pipes are arranged obliquely downwards, the included angle between the foot locking anchor pipe close to the horizontal plane and the horizontal plane is set to be 20 degrees, and the included angle between the adjacent foot locking anchor pipes is set to be 20 degrees.

Set up in the interim supporting construction of shed tunnel bearing structure both sides, interim supporting construction includes the interim stock that the interval set up, and interim stock adopts interval 1.0m's plum blossom type to arrange, and interim stock length is not less than 3.0m.

Set up in the top steel frame crossbeam 27 at shed tunnel bearing structure top, top steel frame crossbeam 27 sets up in its top along main tunnel top contour line. Set up the pipe structure along top steelframe crossbeam 27's contour line interval, including a plurality of pipes 28 that the interval set up among the pipe structure, pipe 28 sets up towards the slope of positive hole bow member top, and pipe 28 arranges the interval and be 3m, length 4.5m, and the tangent line contained angle of pipe and top steelframe crossbeam contour line sets up to 10.

The main hole primary support steel frame structure 29 is arranged in the main hole, one side of the main hole primary support steel frame structure 29 is arranged on a cross beam of the portal steel frame 24 on the outer side of the cross hole reinforcing ring, and the other side of the main hole primary support steel frame structure is arranged on a concrete cushion block 31; and the sections and the arch springing positions of the primary supporting steel frame structure in the main tunnel are respectively provided with a locking anchor pipe with the length of 4m and D42.

3. Main tunnel construction

The main hole comprises a main hole left line and a main hole right line which are parallel.

The small mileage sections of the tunnel main tunnel left line and the main tunnel right line adopt small clear distance control blasting construction, the main tunnel left line and the main tunnel right line are alternately constructed, sand bags are used for backfilling to the maximum span to reduce the influence of vibration on the tunnel in the blasting construction process, and the vibration speed of blasting particles is required to be controlled at 10cm/s.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. used herein refer to the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the products of the present invention are used, and are used for convenience of description and simplicity of description, but do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

Furthermore, the terms "horizontal", "vertical" and the like when used in the description of the present invention do not require that the components be absolutely horizontal or overhanging, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be construed broadly and may include, for example, a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modifications and equivalent variations of the above embodiment according to the technical spirit of the present invention are within the scope of the present invention.

Claims

1. The plateau area tunnel construction method is characterized by comprising the following steps:

in the tunnel excavation step, adopt different construction methods to construct to different country rock ranks, include: constructing by adopting a full-section method aiming at the surrounding rock sections of the III level and the IV level, and constructing by adopting a micro-step method aiming at the surrounding rock section of the V level;

in the blasting construction step, segmenting the transverse tunnel according to the adopted construction mode, surrounding rock level and lining type, classifying all the segments of the transverse tunnel according to the adopted construction mode, surrounding rock level and lining type, generating corresponding blasting schemes according to the characteristic attributes of all the segments of the transverse tunnel under different classifications, and blasting construction is carried out on all the segments of the transverse tunnel according to the blasting schemes;

gradually raising the arch top elevation of the transverse tunnel for construction when the transverse tunnel excavation construction is close to the main tunnel construction position; along the construction direction of the cross tunnel, constructing a shed tunnel from the intersection position of the main tunnel and the cross tunnel to enter the main tunnel, excavating the main tunnel in the intersection section of the cross tunnel and the main tunnel, climbing upwards in an inclined manner to excavate to the center line position of the main tunnel, and reaching the arch top elevation of the main tunnel; the shed tunnel is continuously constructed by excavating a flat slope forwards until the arch springing position of the upper step on the outer side of the main tunnel is constructed; constructing a shed frame in the shed tunnel while constructing the shed tunnel;

and S3, constructing the main tunnel.

2. The plateau area tunnel construction method according to claim 1, wherein in the blasting scheme:

aiming at the class-III surrounding rock, a wedge-shaped cut construction mode is adopted, the depth of a circulating footage is not more than 3.0m, peripheral holes are not ultra-deep, cut holes are not more than 0.4m ultra-deep, and auxiliary Kong Chaoshen is not more than 0.2m;

aiming at IV-level surrounding rock, a wedge-shaped cut construction mode or a straight-hole cut construction mode can be adopted; when a wedge-shaped cut mode is adopted, the circulating depth is not more than 2.4m, the peripheral holes are not ultra-deep, the ultra-deep of the cut hole is not more than 0.4m, and the auxiliary Kong Chaoshen is not more than 0.2m; when a straight-hole cutting mode is adopted, the depth of the circulating depth is not more than 2.4m, peripheral holes are not ultra-deep, the ultra-depth of a cut hole is not more than 0.4m, auxiliary Kong Chaoshen is not more than 0.2m, and crushing Kong Chaoshen 0.2.2 m;

3. The plateau area tunnel construction method according to claim 2, wherein in the blasting scheme:

aiming at class III surrounding rock, the pitch of peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling Kong Kongju is not more than 50cm, the row pitch between tunneling holes is not more than 70cm, the hole pitch of a bottom plate is not more than 80cm, and the row pitch between the bottom plate and a blast hole positioned on the upper side of the bottom plate is not more than 80cm;

aiming at IV-grade surrounding rock, when a wedge-shaped cut construction mode is adopted, the pitch of peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling Kong Kongju is not more than 50cm, the row spacing between the tunneling holes is not more than 80cm, the hole pitch of a bottom plate is 80-100cm, and the row spacing between the bottom plate hole and a blast hole positioned on the upper side of the bottom plate hole is not more than 80cm; when a straight-hole cutting construction mode is adopted, the hole pitch of the peripheral holes is not more than 50cm, the minimum resistance line of the peripheral holes is not more than 60cm, other tunneling Kong Kongju is not more than 50cm, the row pitch between the tunneling holes is not more than 60cm, the hole pitch of the bottom plate is 80-100cm, and the row pitch between the bottom plate hole and the blast hole positioned on the upper side of the bottom plate hole is not more than 80cm;

4. The plateau area tunnel construction method according to claim 3, wherein the lining types adopted in the III-level surrounding rock construction comprise an FS I P-III Pa lining and an FS II P-III Pa lining; the lining types adopted in the IV-level surrounding rock construction comprise an FS I Pjs-IV Ma lining, an FS I P-IV Pa lining and an FS II P-IV Pa lining; the lining types adopted in the construction of the V-level surrounding rock comprise FS II P-VMA lining and FS I P-VMA lining;

blasting construction is carried out to the construction section of same country rock rank and lining cutting type in the cross tunnel to the adoption same blasting scheme, the blasting scheme includes: the method comprises the following steps of arrangement of blast holes on a tunnel face, circulating depth of advance, size of the blast holes, type of blast hole cutting, explosive loading amount, pitch and row spacing of the blast holes and an explosive loading structure.

5. The plateau area tunnel construction method according to claim 1, wherein in the construction of entering the main tunnel and heading the top of the crosscut tunnel, the initial position of the arch top of the crosscut tunnel is determined according to the elevation difference between the crosscut tunnel and the main tunnel, and the elevation gradient of the arch top of the crosscut tunnel is controlled to be not more than 17 degrees.

6. The plateau tunnel construction method according to claim 1, wherein a reinforcing ring is arranged at the joint position of the transverse hole and the main hole, an auxiliary steel frame is arranged in the reinforcing ring, a door-shaped steel frame is arranged on the side, close to the main hole, of the reinforcing ring, the door-shaped steel frame is connected with the auxiliary steel frame in a welding mode in sections, longitudinal steel bars are connected between the adjacent auxiliary steel frames and the door-shaped steel frame, and the distance between the longitudinal steel bars is not more than 1m;

7. The plateau area tunnel construction method according to claim 6, wherein the canopy frame is formed by arranging profile steel supports at intervals along the construction direction of the transverse tunnel, the distance between the profile steel supports is not more than 100cm, a plurality of locking anchor pipes are arranged at each profile steel support foot, the locking anchor pipes at the positions are arranged in an inclined manner downwards, the included angle between the locking anchor pipe close to the horizontal plane and the horizontal plane is 20-30 degrees, and the included angle between adjacent locking anchor pipes is 20-30 degrees;

after the construction of the shed frame is completed, a concrete layer is sprayed on the inner side of the shed frame, a main tunnel primary support steel frame structure is constructed, one side of the main tunnel primary support steel frame structure is arranged on a cross beam of a portal steel frame on the outer side of a cross tunnel reinforcing ring, the other side of the main tunnel primary support steel frame structure is arranged on a concrete cushion block, and two locking anchor pipes are respectively constructed at the joints and the arch feet of the main tunnel primary support steel frame structure.

8. The plateau area tunnel construction method according to claim 1, wherein in the advance support construction step, the tunnel opening section is supported by an advance long pipe shed, and the tunnel body section is supported by an advance medium pipe shed and a single-layer small pipe.

9. The plateau area tunnel construction method according to claim 1, wherein the water-proof and drainage construction in the crossroads comprises the steps of construction joint water-stop belt construction, geotextile and waterproof coiled material construction, waterproof coating spraying construction, drainage blind pipe construction and vault waterproofing construction;

10. The method for constructing the tunnel in the plateau area according to claim 1, wherein the main tunnel comprises a main tunnel left line and a main tunnel right line which are parallel, blasting construction is controlled by small clear distance in the middle and small mileage sections in the main tunnel construction, the main tunnel left line and the main tunnel right line are alternately constructed, sand bags are used for backfilling to the maximum span so as to reduce the influence of vibration on the tunnel in the blasting construction process, and the vibration speed of blasting particles is controlled to be 10cm/s.