CN112431597A - Single-process construction method for monoclinic structure bedding bias soft rock large-deformation tunnel - Google Patents
Single-process construction method for monoclinic structure bedding bias soft rock large-deformation tunnel Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/14—Lining predominantly with metal
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
- E21D20/02—Setting anchoring-bolts with provisions for grouting
- E21D20/021—Grouting with inorganic components, e.g. cement
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/006—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries by making use of blasting methods
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/18—Special adaptations of signalling or alarm devices
Abstract
The invention discloses a single-process construction method for a monoclinic structure bedding bias soft rock large deformation tunnel, which comprises the following steps of: s1, detecting the tunnel construction part to obtain advanced geological forecast; s2, pre-reinforcing the tunnel face according to advance geological forecast, carrying out slope releasing treatment according to the ratio of 1:0.1 during excavation, sealing the tunnel face by C30 sprayed concrete guniting, reinforcing by fiber anchor rods, and arranging according to a quincunx shape, wherein the arrangement angle is basically consistent with the axial direction of the tunnel; s3 blasting and excavating, perforating more holes at the peripheral holes and charging less or charging at intervals, and adopting multi-section differential millisecond detonators; the single-procedure construction method for the monoclinic bedding bias soft rock large-deformation tunnel disclosed by the invention can quickly and effectively form the self-stabilizing stress arch of the surrounding rock and can effectively control the deformation of the surrounding rock; the monocline structure soft rock tunnel adopts the single process construction, and the process organization is simple, does not have other process interferences, and the efficiency of construction is high, and the progress can obtain guaranteeing.
Description
Technical Field
The invention belongs to the technical field of tunnel construction, and particularly relates to a single-process construction method for a monoclinic structure bedding bias soft rock large-deformation tunnel.
Background
At present, more tunnel constructions in China adopt a new Olympic method, the new Olympic method provides powerful guarantee for tunnel construction better under certain conditions by using the advantages of timeliness, sealing property, caking property, flexibility and the like, but the new Olympic method using anchor spraying as an important construction means also has certain defects:
1. in a large deformation section of the soft rock tunnel, the time for the surrounding rock to form a stress arch is long, the deformation speed is high, and the limit of the anchor spraying primary support is easy to be invaded.
2. When a monoclinic structure bedding bias large-deformation tunnel is constructed by adopting a step method or a three-step method, the surrounding rock disturbance is large.
3. In a monoclinic structure bedding bias large deformation tunnel, the surrounding rock instability phenomena such as slipping and collapsing easily occur on the tunnel face when full-section construction is adopted.
Disclosure of Invention
The invention provides a single-process construction method for a monoclinic structure bedding bias soft rock large-deformation tunnel, and aims to solve the existing problems.
The invention is realized in this way, a monoclinic structure bedding bias soft rock large deformation tunnel single-process construction method, comprising the following steps:
s1, detecting the tunnel construction part to obtain advanced geological forecast;
s2, pre-reinforcing the tunnel face according to advance geological forecast, carrying out slope releasing treatment according to the ratio of 1:0.1 during excavation, sealing the tunnel face by C30 sprayed concrete guniting, reinforcing by fiber anchor rods, and arranging according to a quincunx shape, wherein the arrangement angle is basically consistent with the axial direction of the tunnel;
s3 blasting excavation, wherein holes are punched at the peripheral hole part, the powder is filled at small quantity or at intervals, a multi-section micro-differential millisecond detonator is adopted, reverse powder filling is adopted during powder filling, the blast hole is blocked by stemming, and the blocking length is generally not less than 20-30 d of the blast hole;
s4, constructing an advance support, and carrying out advance small conduit grouting support, wherein the annular distance of the advance small conduits is 40cm, the longitudinal distance is 2.4m, the lap joint length is 1.6m, and 50 pipes are arranged in each ring; the slurry permeates and diffuses into the holes or cracks of the surrounding rock under the action of pressure, and a shell-shaped protective structure body is formed around the excavation surface;
s5, excavating in a single step by a step method, wherein the step length is 12-15 m, the excavated arch wall support is not more than 2 trusses at a time, and the inverted arch support is not more than 3 meters at a time; excavating a step under the protection of the upper circulating advanced support, throwing excavated hole slag to a lower step by using an excavator, stopping the tunneling of the upper step when one part of the hole slag is advanced to the length of the upper step of 15m, and carrying out slag discharging operation; after the hole slag stacked on the lower step is discharged, performing two-part or three-part excavation, ensuring that the length of the upper step is 12m, and performing excavation construction by using an inverted arch as a primary support and following the lower step;
s6, primary support, namely, single-process construction support of a step method and a temporary inverted arch is adopted, primary spraying operation is carried out on a tunnel face after excavation and slag discharging are completed, an expanding shell type prestressed anchor rod is adopted for anchor rod application, a reinforcing steel bar net sheet is laid after primary spraying, the steel bar net is overlapped into 1-2 grids, I25I-shaped steel is adopted for an arch frame in a vertical mode, and the distance between the I25I-shaped steel and the 60 cm/truss is adopted; spraying concrete by using a wet spraying machine, controlling the thickness of the sprayed concrete by using a nail burying method on site, spraying the concrete from bottom to top, enabling the spraying angle to be vertical to a sprayed surface, and grouting after the grouting of a reserved grouting pipe is finished if necessary; the temporary inverted arch is constructed after the primary support of the upper step is finished, the upper step is subjected to temporary closed looping, the influence of blasting disturbance on surrounding rocks is reduced, and the temporary inverted arch is dismantled after the construction of the lower step is finished;
s7, monitoring and measuring, and performing primary support reinforcement according to the monitoring and measuring conditions.
Further, in step S6, the anchor rod applying step includes: firstly, positioning anchor rod holes, hanging a central line according to the requirement of designing the distance between anchor rods, and marking the anchor rod hole positions by red paint according to the ruler amount; drilling, namely, ensuring the smoothness and straightness of hole positions by adopting a cross drill bit, determining the size of the drill bit according to the size of the expanded shell, cleaning the hole by adopting high-pressure air after drilling, and checking the hole diameter, the hole depth, the hole pitch and the smoothness and straightness of the drilled hole; thirdly, mounting an anchor rod, pushing the anchor rod along the hole during mounting of the anchor rod, and mounting an anchor rod base plate, a grout stop plug and a nut after the rod body is pushed; leveling the concrete at the primary spraying position to ensure that the base plate is closely attached to the primary support base surface, and performing prestressed tensioning by adopting a pneumatic wrench, wherein the prestressed value is determined according to the design requirement; and fifthly, grouting the anchor rod, adopting 1:1 cement paste, not boosting too fast during grouting so as to facilitate discharging air in the hole, stabilizing the pressure for 3-5 min when the pressure reaches a design value so as to facilitate the penetration of the slurry into the surrounding rock gap.
Further, in step S6, the specific step of erecting the arch center includes: firstly, reserving deformation during arch frame installation; secondly, installing concrete cushion blocks in a gap of 2 m/channel between the arch frame and the base plane when erecting the frame; the primary support arch foot support pad is firm, and the stress area is increased; fourthly, I20b is adopted to longitudinally connect the section steel, the circumferential distance is 2 m/channel, and the integral longitudinal connection of the primary support is strengthened; fifthly, locking feet of the arch truss, wherein the locking feet adopt two rows of locking feet, one row is phi 42 seamless steel pipes 4.5m long and 3.5mm thick, the other row is phi 60 locking feet anchor pipes 6m long and 6mm thick, the construction angle is vertical to the surrounding rock joint according to the site surrounding rock joint, and grouting is carried out after construction.
Further, in step S7, the method specifically includes: monitoring and measuring every day, and confirming on site when red early warning occurs; and when no point location is damaged and loosened, reinforcing the red early warning section to meet the bottom, and immediately reinforcing the primary support on site.
Further, the primary support reinforcement mode comprises: shallow hole grouting, deep hole grouting, lengthened prestressed anchor rod construction and common prestressed anchor rod construction.
Further, shallow hole grouting and deep hole grouting are suitable for being adopted when large deformation occurs and a reinforcing surrounding rock is required to be reinforced to form a larger-range reinforcing ring, and shallow hole grouting parameters are as follows: the grouting pipe is a phi 42 seamless steel pipe, the distance is 1.5 multiplied by 1.5, the length is 4m, the grouting adopts 1:1 cement paste, the reinforcing range is determined according to monitoring measurement, and the grouting pipe is adopted when large-range yellow early warning is generated; the deep hole grouting parameters are as follows: the grouting pipe adopts phi 60 seamless steel pipes, the space is 1.5 multiplied by 1.5, the length is 8m, the grouting adopts 1:1 cement paste, the reinforcing range is determined according to monitoring measurement, and the grouting pipe is adopted when large-range red early warning occurs.
Further, the common prestressed anchor rod reinforcement is implemented according to the following parameters: the anchor rods are phi 25YE anchor rods, the spacing is 1.0 multiplied by 1.0, the length is 4m, the grouting adopts 1:1 cement paste, the reinforcing range is determined according to monitoring measurement, and the anchor rods are adopted when local yellow early warning occurs; the reinforcing construction parameters of the lengthened prestressed anchor rod are as follows: the anchor rods are phi 25YE anchor rods, the spacing is 1.0 multiplied by 1.0, the length is 6m, 1:1 cement paste is adopted for grouting, the reinforcing range is determined according to monitoring measurement, and the anchor rods are adopted when local red early warning occurs.
Compared with the prior art, the invention has the beneficial effects that: the single-procedure construction method for the monoclinic bedding bias soft rock large-deformation tunnel disclosed by the invention can quickly and effectively form the self-stabilizing stress arch of the surrounding rock and can effectively control the deformation of the surrounding rock; the monoclinic structure soft rock tunnel is constructed by adopting a single process, the process organization is simple, other process interference is avoided, the construction efficiency is high, and the progress can be ensured; compared with normal three-step and two-step construction, the monoclinic soft rock tunnel adopting single-process construction reduces surrounding rock disturbance, ensures the sequential connection of the arch frames, and ensures the quality safety of field construction; the monoclinic bedding bias soft rock large deformation tunnel single-process construction method is combined with the tunnel face advanced pre-solid phase, and can effectively stabilize the surrounding rock.
Drawings
FIG. 1 is a schematic view of a single-pass excavation configuration according to the present invention;
FIG. 2 is a graph of the time course of the cross-sectional dome settlement of the present invention;
FIG. 3 is a graph of the convergence of the periphery of the cross-section over time in accordance with the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Further, in the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The monoclinic structure soft rock tunnel construction method is developed on the basis of the new Austrian method, and the core of the construction method is mainly to stabilize surrounding rocks by various detection, prevention, support and reinforcement means so that the surrounding rocks form a natural stress arch, and the construction method can effectively control the deformation of the surrounding rocks under the complex geological conditions and ensure safe and rapid construction. The combination of the new Austrian method and the monoclinic structure soft rock tunnel single-process construction method can effectively prevent, find and control deformation, thereby reducing operation risk, ensuring construction quality and improving construction progress.
Along with the development of the country, the demand on high-speed railways is more and more, the number of long, large and deep-buried railways and tunnels with complex geological conditions is more and more, and geological disasters such as large deformation of surrounding rocks and the like which are difficult to control or have higher cost are often easy to occur under certain geological conditions. The method takes a TST (Tunnel Seismic Tomography) method as an example, the TST method can effectively judge and filter Seismic echoes of a side surface and upper and lower strata, only the echo in front of a palm surface is reserved, and false report can be effectively avoided. The thought of "exploring earlier afterwards to dig" must firmly be established in tunnel construction fully investigates the geological conditions, can ensure tunnel construction safety, improves the construction progress, guarantees construction quality, reduces construction cost.
The tunnel face is pre-reinforced, the stability of the tunnel face is improved by biasing a large deformation tunnel along the layer of a monocline structure, slope releasing treatment is carried out according to the ratio of 1:0.1 during excavation, the tunnel face is sealed by C30 sprayed concrete, and the surface of the sprayed concrete is dense and flat without cracks, falling off, leaking, hollowing and water leakage.
When the surrounding rock on the tunnel face is very poor in stability and very soft, the tunnel face is reinforced by using 12-18 m long phi 25FER fiber anchor rods, the longitudinal lap joint is not less than 2m, and the tunnel face and the surrounding rock are arranged in a quincunx mode at intervals of 1.5 multiplied by 1.5 m. The fiber anchor rod adopts a three-arm drill jumbo leading hole, and the arrangement angle is basically consistent with the axial direction of the tunnel. When the surrounding rock is weak and rich in water and cannot be formed into a hole, the sleeve is required to follow up the hole, the fiber anchor rod is lowered to the designed position through the sleeve, and then the sleeve is withdrawn, so that the fiber anchor rod is installed and grouting operation is carried out. And (3) adopting advanced high-pressure grouting, wherein the grout is single-liquid cement grout, the water cement ratio is 1:1, and the grouting pressure is 3-5 Mpa.
The tunnel adopts blasting excavation, and blasting is used as the instrument of excavation, and its design is significant to whether blasting can succeed. The tunnel is a monoclinic structure bedding bias tunnel, and the blasting design is required to follow the following principle:
1) the blasting design footage should meet the design and specification requirements;
2) the peripheral eye part needs to be perforated more and filled less or filled at intervals;
3) a multi-stage differential millisecond detonator is adopted, so that the phenomenon that the surrounding rock disturbance is caused by shock wave superposition due to simultaneous detonation of fewer stages is avoided;
4) the distance between the peripheral eyes is 30-45 cm, the distance between the peripheral eye resistance lines is 45-60 cm, the relative distance (the distance between the peripheral eyes/the distance between the peripheral eyes resistance lines) is 0.75-0.80, and the distance between the peripheral eyes is the minimum value when the surrounding rock is weak;
5) when charging, the explosive efficiency and the blasting effect are improved by adopting reverse charging;
6) during charging, the charge is not coupled, so that the reduction of the blasting energy caused by the occurrence of a blasting crushing area is avoided, and the blasting effect cannot be achieved;
7) the blast hole is plugged by stemming, and the plugging length is generally not less than 20-30 d of the blast hole;
8) the blasting design is a dynamic design, each cycle needs to be properly adjusted according to the situation of the surrounding rock on site,
the internal meaning of the new Austrian method is as follows: the surrounding rock is protected, the self-bearing capacity of the surrounding rock is fully mobilized and exerted, and the advance support is one of important links of the construction of the soft rock tunnel by adopting the new Austrian method.
The advanced support of the method takes a phi 42 advanced small conduit grouting support as an example, the annular distance of the advanced small conduit is 40cm, the longitudinal distance is 2.4m, the lap joint length is 1.6m, and 50 pipes are arranged in each ring. The small advanced conduit grouting is one of important links of advanced support, the effect of the advanced support can be directly determined, slurry can permeate and diffuse into the holes or cracks of surrounding rock under the action of pressure to improve the physical performance of the surrounding rock, and a shell-shaped protective structure body is formed around an excavation surface.
Selecting grouting parameters:
1) slip casting selection
The mixing proportion of grouting liquid is determined according to the design, double-liquid grouting can be adopted in special sections such as fault broken zones and sand and gravel layers, and the mixing proportion is generally determined according to field tests.
2) Calculation of theoretical grouting amount of single hole
The grouting liquid can be determined according to experiments, and the grouting amount can be calculated according to the theoretical grouting amount of the single hole so as to determine the grouting effect
Q＝πR2Lη (5-1)
R＝(0.6～0.7)L (5-2)
In the formula: q represents the grouting amount; l represents the center distance between two grouting pipes; η represents the rock porosity (determined by design or testing).
3) Selection of grouting pressure
P＝(0.4～0.6)γh (5-3)
In the formula: p grouting pressure, kPa; gamma represents the weight of the surrounding rock, kN/m 3; h represents the thickness of the grouted rock mass.
Referring to fig. 1, the single-step excavation is exemplified by the single-step excavation of the bench method, and the construction method is as follows:
1) strictly controlling the length of the step to be about 12-15 m, strictly controlling the excavated footage arch wall support to be not more than 2 pieces at one time, and strictly controlling the inverted arch support to be not more than 3 meters at one time;
2) under the protection of an upper circulating advance support, excavating a part of steps, throwing excavated hole slag to a lower step by using an excavator, stopping the tunneling of the upper step when the part of the holes reaches the length of the upper step of 15m, and performing slag discharging operation;
3) and after the slag of the hole piled on the lower step is discharged, excavating at the second part or the third part, ensuring that the length of the upper step is 12m, and constructing the inverted arch by primarily supporting the excavation following the lower step.
In the primary support, the method takes a single-hole double-line tunnel as an example, 155 square meters are required to be achieved under the condition of excavating V-level surrounding rocks in area, the height-width ratio is 1:1.2, the section shape is too flat, the stress redistribution of the surrounding rocks after the surrounding rocks are excavated is more unfavorable along with the reduction of the height-width ratio, the maximum principal stress in the surrounding rocks and the maximum bending moment at the vault of a lining are increased sharply, and a plastic area and a large deformation area are easier to appear when the tunnel is a monoclinic soft rock tunnel, so a strong support structure is required to keep the tunnel stable. The larger the tunnel excavation width is, the larger the surrounding rock relaxation range is, the larger the burial depth required to generate the pileup arch effect is, and when the tunnel burial depth cannot meet the pileup arch effect requirement, the stress of the bottom feet of the supporting structure is more concentrated, the primary supporting structure of the tunnel is subjected to larger surrounding rock relaxation load, and the stress condition is more unfavorable.
The tunnel adopts a single-process construction method of a step method and a temporary inverted arch, and the supporting method comprises the following steps:
1) performing primary spraying operation on the tunnel face after excavation and slag discharge are finished;
2) and (3) anchor rod construction: the anchor rod construction function is 'supporting and reinforcing the surrounding rock', the surrounding rock with disturbed periphery after tunnel excavation is limited and restrained from deforming and is supported, and the anchor rod can form an arch reinforcing belt in a loose surrounding rock area after grouting is performed on the anchor rod to play a supporting role. The tunnel anchor rod adopts a phi 25mm expanding shell type prestressed anchor rod, and the concrete construction steps are as follows:
firstly, anchor rods are constructed after primary spraying on a tunnel face is completed;
positioning an anchor rod hole: according to the requirement of designing the distance between the anchor rods, hanging a central line, and marking the hole positions of the anchor rods by red paint according to the size;
drilling: the expansion shell type anchor rod has high requirement on the hole position, a cross drill bit is required to be adopted to ensure that the hole position is straight, the size of the drill bit is determined according to the size of the expansion shell, the anchor rod with a phi 25 rod body and a phi 41 annular tooth surface expansion shell anchoring part is adopted in the tunnel, the phi 50 cross drill bit is adopted in drilling, high-pressure air is adopted to clear the hole after drilling, and whether the hole diameter, the hole depth, the hole distance and the drilling straight degree meet the design requirement is checked.
Fourthly, mounting the anchor rod: need be in the same direction as the hole propelling movement during the stock installation, can not the hammering, can not change the body of rod and prevent to rise the shell and open, installation stock backing plate after the body of rod propelling movement is accomplished, only starch stopper and nut, should notice the position when having the exhaust hole installation on the stock backing plate, need punch the installation again on this stock next door when the installation fails.
Prestress tension: when the anchor rod is installed, the concrete at the primary spraying position is leveled to ensure that the base plate is closely attached to the primary supporting base surface, a pneumatic wrench is adopted for prestress tensioning, and the prestress value is determined according to the design requirement.
Grouting the anchor rod: the grouting liquid is determined according to the design, the 1:1 cement paste is adopted in the tunnel, the pressure is not increased too fast during grouting, air in holes is convenient to discharge, and when the pressure reaches the design value, the pressure is stabilized for 3-5 min, so that the grout can conveniently permeate into surrounding rock gaps.
3) Hanging a net: the reinforcing mesh piece is paved and hung after primary spraying, so that concrete is integrated, a double-layer reinforcing mesh piece needs to be paved when the super-excavation is large due to the fact that a sliding layer or falling blocks exist, the second layer is paved after the first layer is covered by the concrete, and the lapping of the reinforcing mesh piece is 1-2 meshes.
4) Erecting: the arch frame is generally combined with anchor rods, reinforcing mesh and sprayed concrete to serve as a primary supporting structure, a steel frame can generally bear the primary pressure of larger surrounding rocks, a single-inclined structure is adopted in the method for the forward-layer bias tunnel, I25I-shaped steel is adopted as primary supporting section steel, and the distance between the primary supporting section steel and the I25I-shaped steel is 60 cm/truss. The specific construction method comprises the following steps:
firstly, properly reserving deformation quantity according to monitoring and measuring conditions during arch frame installation;
secondly, mounting concrete cushion blocks in a gap of 2 m/channel between the arch frame and the base surface when erecting the frame, ensuring that the arch frame is stressed uniformly, and avoiding larger loose load of surrounding rocks caused by the expansion of loose rings of the surrounding rocks;
the primary support arch springing is firmly supported, because the excavation width is too large, the loose circle range of the excavated surrounding rock is larger, the stress at the arch springing is more concentrated after the primary support is stressed, the arch springing needs to be supported to firmly increase the stress area, and the primary support can sink, crack and deform in a large deformation tunnel if the support cushion is unstable, so that the primary support is unstable;
in the large-deformation tunnel, in order to ensure that the integral longitudinal connection of the primary support needs to be strengthened, I20b longitudinal connecting section steel is adopted in the tunnel, the circumferential distance is 2 m/channel, the longitudinal connecting section steel can be manufactured according to the design requirement, and the longitudinal connecting section steel can be selectively manufactured according to the monitoring measurement value when the design is not required, so that the stability of the primary support is ensured;
the tunnel locking leg adopts double rows of locking legs, wherein one row of the locking legs is 4.5m in length of a phi 42 seamless steel pipe, the wall thickness is 3.5mm, the other row of the locking legs is 6m in length of a phi 60 locking leg anchor pipe, the wall thickness is 6mm, the construction angle is perpendicular to the joint of the surrounding rock as far as possible according to the joint condition of the surrounding rock on site, and grouting is performed after construction.
5) And (3) spraying slurry: the sprayed concrete is sprayed by a wet spraying machine, the thickness of the sprayed concrete is controlled by a nail embedding method on site, the spraying is carried out from bottom to top, the spraying angle is vertical to the sprayed surface, and grouting is carried out after the grouting of a reserved grouting pipe is finished if necessary.
6) Temporary inverted arch: the temporary inverted arch is constructed after the primary support of the upper step is completed, the purpose is to perform temporary sealing and looping on the upper step, the influence of blasting disturbance on surrounding rocks is reduced, and the temporary inverted arch is dismantled after the construction of the lower step is completed.
The monitoring measurement is taken as the core of the Xinao method, plays a great guiding role in the field construction process, the main monitoring items of the tunnel are vault sinking and clearance convergence, and the monitoring frequency is as follows:
note: according to the table, the measurement frequency is measured according to the highest frequency, and in special cases, the frequency table 1 needs to be increased to monitor the measured frequency and compare the single-process construction of the step method with the deformation control effect of the three-step method:
note: the table adopts similar sections of the surrounding rock of the tunnel face and adopts different construction methods to carry out construction deformation control effect to compare with the table 2 monitoring measurement analysis table
Through comprehensive analysis of Table 2, FIG. 2 and FIG. 3, the average vault settlement value of single-process construction by a step method is about 115mm, and the average peripheral convergence value is about 100 mm; the average vault settlement value is about 330mm on average and the peripheral convergence value is about 400mm on average when the traditional three-step construction method is adopted; the deformation of the single-process construction by adopting a step method is relatively large within one week, and finally the deformation gradually tends to be stable and is small; the three-step method adopted by the traditional V-level surrounding rock gradually becomes stable after 25 days of average construction, but the deformation is severe every day before; compared with the three-step method, the single step method controls the deformation value to be about one third of the original deformation value.
The tunnel is according to the control condition of measurationing in the broken or poor special district of steady ability of country rock, often need adopt the mode of slip casting to consolidate the country rock for avoiding big deformation, forms reinforcing area on a relatively large scale, and concrete construction method is as follows:
1) monitoring and measuring are carried out according to the measuring frequency shown in the table 1 every day, when red early warning occurs, on-site confirmation is carried out, when no point location damage and point location looseness exist, reinforcement and intersection are required to be carried out on a red early warning section immediately, and initial support reinforcement is required to be carried out on the site immediately.
2) This tunnel is monoclinic structure bedding biasing tunnel, very easily takes place to warp, and the mode of just propping up the reinforcement and adopting has: shallow hole grouting, deep hole grouting, lengthened prestressed anchor rod construction and common prestressed anchor rod construction.
3) Shallow hole slip casting and deep hole slip casting are applicable to and take place the major deformation and need the reinforcement country rock to adopt when forming wider range reinforcing ring, and this tunnel shallow hole slip casting parameter is: the grouting pipe is made of phi 42 seamless steel pipes, the distance is 1.5 multiplied by 1.5 (ring multiplied by longitudinal), the length is 4m, 1:1 cement paste is adopted for grouting, the grouting amount and the grouting pressure are determined according to formulas 5-1 and 5-3, and the reinforcing range is determined according to monitoring measurement (generally adopted when large-range yellow early warning occurs). The deep hole grouting parameters are as follows: the grouting pipe is made of phi 60 seamless steel pipes, the distance is 1.5 multiplied by 1.5 (ring multiplied by longitudinal), the length is 8m, 1:1 cement paste is adopted for grouting, the grouting amount and the grouting pressure are determined according to formulas 5-1 and 5-3, and the reinforcing range is determined according to monitoring measurement (generally adopted when large-range red early warning occurs).
4) The method is suitable for being adopted when the local reinforcement is needed for the primary support, and the common prestressed anchor rod reinforcement of the tunnel has the following construction parameters: the anchor rods are phi 25YE anchor rods, the spacing is 1.0 multiplied by 1.0 (ring multiplied by longitudinal), the length is 4m, the grouting adopts 1:1 cement paste, the grouting amount and the grouting pressure are determined according to formulas 5-1 and 5-3, and the reinforcing range is determined according to monitoring measurement (generally adopted when local yellow early warning occurs). The reinforcing construction parameters of the lengthened prestressed anchor rod are as follows: the anchor rods are phi 25YE anchor rods, the spacing is 1.0 multiplied by 1.0 (ring multiplied by longitudinal), the length is 6m, 1:1 cement paste is adopted for grouting, the grouting amount and the grouting pressure are determined according to formulas 5-1 and 5-3, and the reinforcing range is determined according to monitoring measurement (generally adopted when local red early warning occurs).
The single-procedure construction method for the monoclinic bedding bias soft rock large-deformation tunnel disclosed by the invention can quickly and effectively form the self-stabilizing stress arch of the surrounding rock and can effectively control the deformation of the surrounding rock; the monoclinic structure soft rock tunnel is constructed by adopting a single process, the process organization is simple, other process interference is avoided, the construction efficiency is high, and the progress can be ensured; compared with normal three-step and two-step construction, the monoclinic soft rock tunnel adopting single-process construction reduces surrounding rock disturbance, ensures the sequential connection of the arch frames, and ensures the quality safety of field construction; the monoclinic bedding bias soft rock large deformation tunnel single-process construction method is combined with the tunnel face advanced pre-solid phase, and can effectively stabilize the surrounding rock.
The tunnel adopts single process construction technology, namely: the construction method needs to be matched with temporary inverted arches, longitudinal connecting section steel, large locking feet and high-pressure grouting reinforcement for construction, can reduce the disturbance of blasting on surrounding rocks by adopting single-process circulation operation, and realizes safe and rapid construction of the soft rock large deformation tunnel by adopting a method of 'single circulation, weak blasting, ring formation and surrounding rock stabilization'.
The tunnel face pre-reinforcement technology is used for increasing the stability of a tunnel face in a monoclinic structure bedding-following bias large-deformation tunnel, slope releasing treatment is carried out according to the ratio of 1:0.1 during excavation, the tunnel face is sealed by C30 sprayed concrete guniting, and the sprayed concrete surface is dense and flat without cracks, falling off, leaking, hollowing and water leakage.
The primary support reinforcing technology adopts shallow hole grouting, deep hole grouting, lengthened prestressed anchor rods and common prestressed anchor rods to carry out high-pressure grouting reinforcement on weak surrounding rocks, grout can permeate and diffuse into surrounding rock pores or cracks under the action of high pressure to improve the physical properties of the surrounding rocks, and a shell-shaped protective structure body is formed around the primary support structure surface so as to achieve the purposes of protecting the surrounding rocks, fully mobilizing and exerting the self-bearing capacity of the surrounding rocks.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A monoclinic structure bedding bias soft rock large deformation tunnel single-process construction method is characterized by comprising the following steps:
s1, detecting the tunnel construction part to obtain advanced geological forecast;
s2, pre-reinforcing the tunnel face according to advance geological forecast, carrying out slope releasing treatment according to the ratio of 1:0.1 during excavation, sealing the tunnel face by C30 sprayed concrete guniting, reinforcing by fiber anchor rods, and arranging according to a quincunx shape, wherein the arrangement angle is basically consistent with the axial direction of the tunnel;
s3 blasting excavation, wherein holes are punched at the peripheral hole part, the powder is filled at small quantity or at intervals, a multi-section micro-differential millisecond detonator is adopted, reverse powder filling is adopted during powder filling, the blast hole is blocked by stemming, and the blocking length is generally not less than 20-30 d of the blast hole;
s4, constructing an advance support, and carrying out advance small conduit grouting support, wherein the annular distance of the advance small conduits is 40cm, the longitudinal distance is 2.4m, the lap joint length is 1.6m, and 50 pipes are arranged in each ring; the slurry permeates and diffuses into the holes or cracks of the surrounding rock under the action of pressure, and a shell-shaped protective structure body is formed around the excavation surface;
s5, excavating in a single step by a step method, wherein the step length is 12-15 m, the excavated arch wall support is not more than 2 trusses at a time, and the inverted arch support is not more than 3 meters at a time; excavating a step under the protection of the upper circulating advanced support, throwing excavated hole slag to a lower step by using an excavator, stopping the tunneling of the upper step when one part of the hole slag is advanced to the length of the upper step of 15m, and carrying out slag discharging operation; after the hole slag stacked on the lower step is discharged, performing two-part or three-part excavation, ensuring that the length of the upper step is 12m, and performing excavation construction by using an inverted arch as a primary support and following the lower step;
s6, primary support, namely, single-process construction support of a step method and a temporary inverted arch is adopted, primary spraying operation is carried out on a tunnel face after excavation and slag discharging are completed, an expanding shell type prestressed anchor rod is adopted for anchor rod application, a reinforcing steel bar net sheet is laid after primary spraying, the steel bar net is overlapped into 1-2 grids, I25I-shaped steel is adopted for an arch frame in a vertical mode, and the distance between the I25I-shaped steel and the 60 cm/truss is adopted; spraying concrete by using a wet spraying machine, controlling the thickness of the sprayed concrete by using a nail burying method on site, spraying the concrete from bottom to top, enabling the spraying angle to be vertical to a sprayed surface, and grouting after the grouting of a reserved grouting pipe is finished if necessary; the temporary inverted arch is constructed after the primary support of the upper step is finished, the upper step is subjected to temporary closed looping, the influence of blasting disturbance on surrounding rocks is reduced, and the temporary inverted arch is dismantled after the construction of the lower step is finished;
s7, monitoring and measuring, and performing primary support reinforcement according to the monitoring and measuring conditions.
2. The construction method according to claim 1, wherein in step S6, the concrete step of applying the anchor rod comprises: firstly, positioning anchor rod holes, hanging a central line according to the requirement of designing the distance between anchor rods, and marking the anchor rod hole positions by red paint according to the ruler amount; drilling, namely, ensuring the smoothness and straightness of hole positions by adopting a cross drill bit, determining the size of the drill bit according to the size of the expanded shell, cleaning the hole by adopting high-pressure air after drilling, and checking the hole diameter, the hole depth, the hole pitch and the smoothness and straightness of the drilled hole; thirdly, mounting an anchor rod, pushing the anchor rod along the hole during mounting of the anchor rod, and mounting an anchor rod base plate, a grout stop plug and a nut after the rod body is pushed; leveling the concrete at the primary spraying position to ensure that the base plate is closely attached to the primary support base surface, and performing prestressed tensioning by adopting a pneumatic wrench, wherein the prestressed value is determined according to the design requirement; and fifthly, grouting the anchor rod, adopting 1:1 cement paste, not boosting too fast during grouting so as to facilitate discharging air in the hole, stabilizing the pressure for 3-5 min when the pressure reaches a design value so as to facilitate the penetration of the slurry into the surrounding rock gap.
3. The construction method according to claim 1, wherein the concrete step of erecting the arch in step S6 includes: firstly, reserving deformation during arch frame installation; secondly, installing concrete cushion blocks in a gap of 2 m/channel between the arch frame and the base plane when erecting the frame; the primary support arch foot support pad is firm, and the stress area is increased; fourthly, I20b is adopted to longitudinally connect the section steel, the circumferential distance is 2 m/channel, and the integral longitudinal connection of the primary support is strengthened; fifthly, locking feet of the arch truss, wherein the locking feet adopt two rows of locking feet, one row is phi 42 seamless steel pipes 4.5m long and 3.5mm thick, the other row is phi 60 locking feet anchor pipes 6m long and 6mm thick, the construction angle is vertical to the surrounding rock joint according to the site surrounding rock joint, and grouting is carried out after construction.
4. The construction method according to claim 1, wherein in step S7, the method specifically comprises: monitoring and measuring every day, and confirming on site when red early warning occurs; and when no point location is damaged and loosened, reinforcing the red early warning section to meet the bottom, and immediately reinforcing the primary support on site.
5. The construction method according to claim 4, wherein: the primary support reinforcing mode comprises the following steps: shallow hole grouting, deep hole grouting, lengthened prestressed anchor rod construction and common prestressed anchor rod construction.
6. The construction method according to claim 5, wherein: shallow hole slip casting and deep hole slip casting are applicable to and take place the major deformation and need the reinforcing surrounding rock to adopt when forming wider range reinforcing ring, and shallow hole slip casting parameter is: the grouting pipe is a phi 42 seamless steel pipe, the distance is 1.5 multiplied by 1.5, the length is 4m, the grouting adopts 1:1 cement paste, the reinforcing range is determined according to monitoring measurement, and the grouting pipe is adopted when large-range yellow early warning is generated; the deep hole grouting parameters are as follows: the grouting pipe adopts phi 60 seamless steel pipes, the space is 1.5 multiplied by 1.5, the length is 8m, the grouting adopts 1:1 cement paste, the reinforcing range is determined according to monitoring measurement, and the grouting pipe is adopted when large-range red early warning occurs.
7. The construction method according to claim 5, wherein: the common prestressed anchor rod reinforcement construction parameters are as follows: the anchor rods are phi 25YE anchor rods, the spacing is 1.0 multiplied by 1.0, the length is 4m, the grouting adopts 1:1 cement paste, the reinforcing range is determined according to monitoring measurement, and the anchor rods are adopted when local yellow early warning occurs; the reinforcing construction parameters of the lengthened prestressed anchor rod are as follows: the anchor rods are phi 25YE anchor rods, the spacing is 1.0 multiplied by 1.0, the length is 6m, 1:1 cement paste is adopted for grouting, the reinforcing range is determined according to monitoring measurement, and the anchor rods are adopted when local red early warning occurs.
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