CN114483054A - Non-explosive excavation construction method for pilot tunnel in upper soft and lower hard stratum - Google Patents

Abstract

The invention discloses a non-explosive excavation construction method for a pilot tunnel in a soft upper stratum and a hard lower stratum, which aims to solve the technical problems of slow excavation progress and high difficulty in control of over-under excavation in the non-explosive excavation construction technology of the pilot tunnel; the invention comprises the following steps: s1, advance geological exploration; s2, advance support; s3, excavating a soil layer for supporting; s4, super undermining the control hole; s5, excavating and supporting rock stratum; s6, sealing the inverted arch; the invention makes full use of various mature seed devices for combined construction, each process can be closely connected, the construction efficiency is improved, the construction period is shortened, the tunnel overexcavation is reduced, the construction cost is reduced, the problems of high construction risk, slow progress and large overall construction difficulty of the upper soft and lower hard composite stratum are solved, and meanwhile, the settlement deformation of the upper soft and weak stratum is effectively controlled.

Description

Non-explosive excavation construction method for pilot tunnel in upper soft and lower hard stratum

Technical Field

The invention relates to the technical field of tunnel engineering, in particular to a non-explosive excavation construction method for pilot tunnels of upper soft and lower hard strata.

Background

With the development of the urban modernization process, public transport cannot meet the travel requirements of people only depending on ground space, and the building of underground railways is a necessary result of urban development, and is a necessary measure for relieving traffic jam and encouraging public transport travel; the subway line is mostly provided with a shallow buried main road and a building penetrating through a central urban area, and tunnel construction of the sections is still conducted by a drilling and blasting method. In order to ensure the safety of residents, structures and buildings on the earth surface, the drilling and blasting method construction must adopt blasting vibration control technology. However, even if the blasting vibration control technology is advanced, the blasting vibration can be reduced to the maximum extent, and the control fluctuation of the vibration speed of the blasting vibration is large, so that the influence on residents is easily caused. When shallow tunnel excavation construction is carried out in an urban environment where surface buildings are erected, non-blasting excavation is often a method which has to be selected for a section where the underground penetration of structures with low earth surface seismic resistance levels is difficult or a section where blasting vibration is not allowed to be generated.

The non-explosive rock excavation means includes a silent breaking agent excavation method, a milling and excavating machine milling and excavating method, a splitter splitting method, a shield method, a tunneling machine (TBM) method, a free section tunneling machine method, a core-taking and hole-forming method and the like. The construction methods need to face the empty surface, work efficiency is low, or equipment investment is too large, and the construction methods are not economical for short-distance difficult sections, and the problems of tunnel excavation of the composite stratum, particularly the problems of slow excavation progress, high difficulty in over-excavation and under-excavation control and the like of the upper soft and lower hard irregular stratum are difficult to solve by a single construction method.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is known to a person skilled in the art.

Disclosure of Invention

The invention aims to provide a non-explosive excavation construction method for pilot tunnels in a soft upper stratum and a hard lower stratum, and aims to solve the technical problems of slow excavation progress and high difficulty in controlling over-under excavation in the non-explosive excavation construction technology.

In order to solve the technical problems, the invention adopts the following technical scheme:

designing a non-explosive excavating construction method for pilot tunnels of upper soft and lower hard strata, comprising the following steps:

s1, surveying the unfavorable geological section in the tunneling range before excavation, and determining the specific position area of the upper soft and lower hard stratum;

s2, when excavating to the area near the upper soft lower hard area, performing pipe shed support on the arch part of the pilot tunnel to prevent the arch crown from falling blocks during construction;

s3, excavating the soil layer part of the upper step by using a small excavator with the rock-soil layer interface as a reference surface, installing an upper step special-shaped arch center after the excavation is finished, then constructing a foot locking anchor rod, hanging a reinforcing steel bar net piece, and spraying concrete slurry;

s4, adding control holes on the periphery of the face by adopting a shallow hole drilling machine, simulating and calculating the drilling angle according to the circulating footage, and arranging the control holes in a staggered manner along the length of the excavation contour line;

s5, excavating and excavating the lower step rock stratum part by using a cantilever excavator;

s6, after excavating a distance on the tunnel face, excavating an inverted arch by using a cantilever excavator;

and S7, repeating the steps S3-S6 for the next cycle of excavation.

Preferably, the pipe shed support adopts a large encrypted pipe shed, the distance between the pipe sheds is 15-20 cm, and the diameter is phi 108 mm.

Preferably, the cross section of the pipe shed adopts a mode of outward expansion of an arch part, the arch part excavation contour line is integrally upwards and outwardly expanded by 80-100 cm, and the side wall contour line is unchanged.

Preferably, in step S3, the excavation footage is controlled to be 0.5 to 1m, and the layout of the upper step and the lower step is controlled to be within 3 m.

Preferably, the special-shaped arch center installation comprises the following steps:

1) firstly, machining a special-shaped steel frame in advance according to the size of an upper step, wherein the arch foot short section steel frames are spaced by 10-15 cm when the special-shaped steel frame is segmented;

2) before the special-shaped steel frame is installed, firstly measuring the size of the end face of an upper step to be supported, taking the arch springing of the upper step falling on a rock stratum as a reference, and selecting an arch springing short section steel frame;

3) if a small amount of underexcavation exists, performing chiseling treatment by using a gun; if the overexcavation exists, square wood or steel is adopted for solid padding.

Preferably, in the step S4, the hole diameter of the control holes is between 70 and 80mm, and the clear distance between the control holes is between 20 and 30 cm.

Preferably, the step S5 includes:

1) after the cantilever excavator is in place, cutting a groove from the bottom of a tunnel face along the horizontal direction, and reserving an excavation face of 0.8-1 m;

2) the cutting head of the cantilever excavator adopts top-down, left-right circular cutting;

3) 1-2 trusses of cantilever tunneling machine are advanced in each cycle, grid steel frames on two sides are firstly supported, and an inverted arch lags behind the tail of the cantilever tunneling machine by 3-5 m;

4) and loading the cut residue soil into a transport vehicle by a shovel plate part rake claw of the cantilever excavator, transporting the residue soil to a vertical shaft temporary residue soil pit, and lifting the residue soil pit out of the hole by a bridge crane.

Compared with the prior art, the invention has the main beneficial technical effects that:

the invention makes full use of various mature seed devices for combined construction, each process can be closely connected, the construction efficiency is improved, the construction period is shortened, the tunnel overexcavation is reduced, the construction cost is reduced, the problems of high construction risk, slow progress and large overall construction difficulty of the upper soft and lower hard composite stratum are solved, and meanwhile, the settlement deformation of the upper soft and weak stratum is effectively controlled.

Drawings

FIG. 1 is a longitudinal cross-sectional view of a pilot hole in the practice of the present invention.

FIG. 2 is a plan view of a pilot hole in the practice of the present invention.

FIG. 3 is a schematic cross-sectional view of the pilot hole of the present invention.

Fig. 4 is a schematic cross-sectional structure diagram of the pipe shed working room of the invention.

FIG. 5 is a cross-sectional view of the grid steel frame according to the present invention.

FIG. 6 is a schematic view of a large sample structure of the grid steel frame of the present invention.

Detailed Description

The following examples are intended to illustrate the present invention in detail and should not be construed as limiting the scope of the present invention in any way.

Example 1: a non-explosive excavation construction method for pilot holes in upper soft and lower hard strata includes the following steps with reference to figures 1 to 6:

s1, construction preparation:

1) preparing supporting facilities:

the excavator adopts 1140V high pressure, prepares a 1140V box transformer with high pressure, prepares cables (from the box transformer to the excavation work place), wind and water pipes, a matched excavator and a transport vehicle with corresponding length for deslagging, and the preparation work is a precondition for the construction of the cross-channel excavator.

2) Advanced geophysical prospecting matching:

by adopting a geological advanced forecasting technology, geological disasters such as collapse, water gushing, sand running, soil gushing and the like which are possibly encountered in construction are reduced or avoided; advance forecasting measures such as advance horizontal drilling and the like are adopted to detect the geology of the upper soft rock stratum and the lower hard rock stratum in front, so that the safe operation of equipment and personnel is ensured.

3) Equipment type selection:

the rock saturated compressive strength Rc disclosed by a detailed survey report is maximally over 70MPa, a tunneling machine with model number XTR4/230 is selected for construction according to the stratum condition, underground excavation section excavation (without an inverted arch part) can be completed at one time, and stepped tunneling excavation can be performed according to the rock and soil boundary condition.

S2, personnel configuration:

in order to ensure 24-hour uninterrupted construction of the tunnel, a tunneling worker class performs a two-class system, and supporting constructors of tunnel tunneling machines of each class take turns to work for 8 hours each class, wherein the specific personnel and mechanical configuration is as follows: the method comprises the following steps that 18 persons in each class are allocated by personnel, wherein the personnel comprise 2 persons of a main manipulator and an auxiliary manipulator of a development machine, 2 persons of a matched manipulator, 1 person of tunnel face observation, 3 persons of cleaning muck, 2 persons of cable transfer, 1 person of maintenance worker, 1 person of electrician, 1 person of welder, 2 persons of an excavator manipulator, 2 persons of a muck truck driver and 1 person of coordination command; 5 mechanical devices are arranged, wherein 1 tunneling machine, 1 excavator and 2 muck transport vehicles are arranged.

S3, advance support:

firstly, constructing a phi 108 advanced large pipe shed 1 at the arch part of a pilot tunnel, and according to the characteristics of upper soft and lower hard strata, adopting an encrypted advanced large pipe shed 1 for the advance support of the pilot tunnel in order to prevent the vault from falling during pilot tunnel excavation construction, wherein the distance between the advanced large pipe sheds 1 is 15-20 cm, and the diameter is 108 mm; in addition, the section 8 of the pipe shed working room is optimized, the traditional mode of expanding the arch wall outwards is changed into the mode of expanding the arch part outwards, the whole arch part excavation contour line 9 is expanded upwards by 80-100 cm, the side wall contour line is unchanged, the construction precision and the construction quality of the advanced large pipe shed 1 can be effectively controlled, and the construction risk of expanding the pipe shed outside is reduced; aiming at a water-rich sand layer or other complex stratums, a flange is arranged at an orifice of each guide pipe as an emergency plugging measure, so that the water gushing and sand gushing during drilling can be plugged at the first time, the construction operation risk is reduced, and conditions are provided for excavation of an underground excavation tunnel.

S4, excavating and supporting:

because the small pilot tunnel is positioned in a soft upper hard stratum and a hard lower hard stratum, the rock surface fluctuation is very large, and the height difference of the rock surfaces of the arch springing at the two sides of the pilot tunnel is also very large, the traditional step method can not be adopted for construction. According to the actual situation of a site, a traditional step method is optimized into a special-shaped step by taking a rock-soil interface 10 as a reference, wherein the upper step is a soil layer 2, and the lower step is a rock layer 3; the method takes the step-by-step rapid sealing as a basic principle to rapidly finish the sealing of the primary support structure 6, reduce the exposure time of the upper step soil layer 2 and reduce the risk of tunnel excavation construction; and (3) performing pilot tunnel excavation according to the sequence of 'soil layer 2 excavation support → super short excavation control hole 4 → rock layer 3 excavation support':

1) and (5) excavating and supporting a soil layer 2: a small excavator is used for excavating the 2 parts of the upper step soil layer, the excavating footage is controlled to be 0.5-1.0 m, the layout of the upper step and the lower step is controlled to be within 3m, and the normal operation space of the excavator is guaranteed. After the excavation is finished, installing the upper step special-shaped arch centering, selecting a proper arch centering, quickly finishing the installation, then applying a locking anchor rod 12, hanging a reinforcing mesh sheet, and spraying concrete for quick sealing; according to the size of the different-shaped steps, the different-shaped steel frames are processed in advance, and when the different-shaped steel frames are divided, the arch foot short-section grid steel frames 11 need to be processed into different sizes, preferably at intervals of 10-15 cm; before the field grid steel frame 14 is installed, a technician firstly measures the section size of an upper step to be supported, selects a proper short section grid steel frame 11 on the principle that a special-shaped upper step arch foot falls on a rock stratum 3, and performs chiseling treatment by using a gun if a small amount of underexcavation exists; if the overexcavation exists, adopting square wood or section steel for tamping; the lower step steelframe matches according to the last step bow member lectotype, realizes the accurate closed loop of primary support steelframe through building the block form. In addition, a telescopic energy dissipation arch frame can be adopted in the uniformly deformed surrounding rock. In order to effectively control the settlement of the primary support structure 6 of the weak stratum, the tunnel foot-locking anchor pipe is used for stabilizing a steel frame in primary support so as to prevent the arch foot from contracting and falling. The connection between the foot-locking anchor rod 12 and the steel frame adopts an in-field pre-welding foot-locking positioning sleeve 13 method, which can ensure the welding quality and the angle of the foot-locking anchor rod 12. The problem that the traditional connecting rib mode is easy to desolder, so that the foot locking anchor rod 12 is invalid and sinks greatly is solved. In addition, in the diameter and the length of the foot-locking anchor rod 12 in the special surrounding rock section, the middle step and the lower step have the condition of mechanically constructing the large-diameter foot-locking anchor rod 12, the length of the foot-locking anchor rod 12 can be extended into the range of the lower step, and the body of the foot-locking anchor rod 12 is filled with a large-diameter steel pipe (the diameter is not less than 70 mm) through grouting. The early strength and the high strength of the primary support are improved at the height of the weak surrounding rock section, the early strength and the high strength can be controlled according to the strength index of 12h, and the strength of the arch springing part is particularly required to be paid attention to in the construction process. Aiming at the deformation of the arch springing part caused by the easy deformation in the range of 1m above the arch springing, the connecting part of the steel frame can be determined according to the excavation height and staggered joint is carried out, especially the arch crown part. If the joint steel frame of the inverted arch with the large deformation section is deformed and is difficult to bolt, the joint steel frame can be reinforced by the welding ribs.

2) Drilling at the periphery of a rock stratum 3: in order to effectively control the overbreak and underbreak, two rows of overbreak and underbreak control holes 4 are additionally arranged on the periphery of the face, the drilling angle is calculated in a simulation mode according to the circulating footage, the diameter of each drilling hole is 70-80 mm, the net distance is 20-30 cm, long holes and short holes are arranged along the excavation contour line 9 in a staggered mode, a crawler-type down-the-hole drilling machine is adopted for operation, an operator uses the peripheral overbreak and underbreak control holes 4 as a reference, the tunneling excavation and overbreak are effectively controlled, the underbreak workload is reduced, and the construction cost is reduced.

3) And (3) excavating and supporting rock stratum 3: after the primary support of the upper step soil layer 2 is completed, the lower step rock layer 3 is dug and excavated by a cantilever excavator. After the cantilever heading machine is in place, a groove is horizontally cut from the bottom of the tunnel face, the heading machine is moved forward to be in place again, and the cutting head is circularly cut left and right from top to bottom after being in place. Cutting and tunneling are carried out on the tunnel face by using the cutting part, the cut slag is loaded into an in-hole transport vehicle by the shovel part harrow claws during cutting, the in-hole transport vehicle is transported into a vertical shaft slag pit, then the temporary slag pit is transferred to a ground temporary slag pit by using a bridge crane, and an excavator is loaded into a slag transport vehicle and transported to a specified slag abandoning field. And after the arch part is excavated from the bottom, performing secondary trimming to accurately design the section. When hard rock is locally encountered (more than or equal to 60 MPa), peripheral soft rock is tunneled first, so that large hard rock falls, and the tunneling difficulty and the pick consumption are reduced. The cutting mode of the cantilever excavator is that the cutting is started from the bottom sweeping, and then the parts are cut step by step according to an S-shaped or Z-shaped left-right circular upward cutting route. The right-handed cutting head is selected to cut the hard rock, the hard rock is cut from bottom sweeping from right to left, and then the hard rock is cut step by step from left to right and from bottom to top or from right to left and from top to bottom. If the rock with higher joint development is encountered, the rock joint direction is selected to be cut step by step; and after the tunneling is finished, the machine moves back to a position where the follow-up construction is not influenced to wait for the next circulating tunneling process. The inverted arch part and the side wall are formed in one-step, full mechanical excavation is achieved during excavation of the whole tunnel, disturbance on surrounding rocks is small, and influence on surrounding buildings is avoided. And (3) firstly supporting grid steel frames 14 at two sides and lagging an inverted arch by 3-5 m after the cantilever tunneling machine advances 1-2 frames per cycle. If the surrounding rock of the tunnel face is unstable, the excavation construction method is adjusted to be staggered from left to right for construction, and the staggered distance is 5-8 m. Because the cutting head of the cantilever heading machine is long, an excavation surface of 0.8-1.0 m is reserved on the tunnel face during each heading so as to prevent the tunnel face from being too large due to the fact that the excavation of the next time damages the manufactured primary support.

The cantilever type heading machine has the advantages that disturbance of surrounding rocks is small in tunnel construction, adaptability is strong, overbreak is effectively controlled, two rows of control holes are additionally arranged on the periphery of a tunnel face, drilling angles are calculated in a simulation mode according to cyclic footage, excavation quality is improved, the smoothness of excavation sections of a cavern is high, concrete spraying support is facilitated, construction period is shortened, and safety is guaranteed.

S5, inverted arch sealing:

the inverted arch part and the side wall are excavated separately, and the cantilever excavator is also adopted for excavation and molding, so that the disturbance to surrounding rocks is small, and the influence on surrounding buildings is avoided. According to the required operating space (distance) of the cantilever tunneling machine, after the tunnel face is excavated for a certain distance, the inverted arch begins to be excavated, one section of inverted arch is constructed every five meters, and the inverted arch lags behind the tail part of the cantilever tunneling machine by 3-5 m so as to ensure the cantilever tunneling operating distance. Then installing a grid steel frame 14, sealing the net sprayed concrete, and adding a concrete pavement with the thickness of 20cm on the basis of the inverted arch primary support concrete to meet the traveling requirement of the cantilever excavator, wherein the early strength concrete is adopted; and finally, paving a 2 cm-thick steel plate on the newly cast concrete pavement to avoid crushing the pavement when the tunneling machine walks or works.

Because the cutting head of the cantilever heading machine is long and is limited by the operation space, the side wall steel frame of the finished supporting structure is easily damaged by the heading machine; in order to avoid the damage of the primary support structure 6 and ensure the safety and stability of the structure, a tunneling operation space of 0.8-1.0 m is reserved on the tunnel face when the cantilever machine tunnels, and a protective device of the primary support structure 6, namely an L-shaped steel frame protective plate 5, is specially designed. The guard plate adopts 2cm thick steel plate welding to form, and the guard plate becomes the L type, and bottom installation walking pulley makes things convenient for the location installation, is provided with the preformed hole on the L shaped steel frame guard plate 5, through the anchor hole, beats and establishes the anchor reinforcing bar and fixes, and this kind of method has avoided the cantilever machine to dig when operation the destruction to just supporting structure 6.

While the invention has been described in detail with reference to the drawings and examples, it will be understood by those skilled in the art that various changes in the details of the embodiments may be made without departing from the spirit of the invention, and various changes in the details of construction and materials may be substituted for elements thereof to form various embodiments, which are within the scope of the invention and are not intended to be limited to the details of the embodiments.

Claims (7)

1. A non-explosive excavation construction method for pilot tunnels of upper soft and lower hard strata is characterized by comprising the following steps:

s1, surveying the unfavorable geological section in the tunneling range before excavation, and determining the specific position area of the upper soft and lower hard stratum;

s2, when excavating to the area near the upper soft lower hard area, performing pipe shed support on the arch part of the pilot tunnel to prevent the arch crown from falling blocks during construction;

s3, excavating the soil layer part of the upper step by using a small excavator with the rock-soil layer interface as a reference surface, installing an upper step special-shaped arch center after the excavation is finished, then constructing a foot locking anchor rod, hanging a reinforcing steel bar net piece, and spraying concrete slurry;

s4, adding control holes on the periphery of the face by adopting a shallow hole drilling machine, simulating and calculating the drilling angle according to the circulating footage, and arranging the drilling angles in a length-staggered manner along the excavation contour line;

s5, excavating and excavating the lower step rock stratum part by using a cantilever excavator;

s6, after excavating a distance on the tunnel face, excavating an inverted arch by using a cantilever excavator;

and S7, repeating the steps S3-S6 for the next cycle of excavation.

2. The non-explosive excavation construction method of the pilot tunnel of the upper soft and lower hard formation according to claim 1, characterized in that the pipe shed support adopts a large encrypted pipe shed, the pipe shed spacing is 15-20 cm, and the diameter is phi 108 mm.

3. The non-explosive excavation construction method for the pilot tunnel in the upper soft and lower hard formation according to claim 2, characterized in that the arch excavation contour line of the whole arch is expanded upwards by 80-100 cm in a way that the arch is expanded outwards on the section of the pipe shed, and the side wall contour line is unchanged.

4. The non-explosive excavation construction method of the pilot tunnel in the upper soft lower hard formation according to claim 1, wherein in the step S3, the excavation footage is controlled to be 0.5-1 m, and the layout of the upper step and the lower step is controlled to be within 3 m.

5. The non-explosive excavation construction method for the pilot tunnel in the upper soft and lower hard formation according to claim 4, wherein the installation of the special-shaped arch comprises the following steps:

1) firstly, machining a special-shaped steel frame in advance according to the size of an upper step, wherein the arch foot short section steel frames are spaced by 10-15 cm when the special-shaped steel frame is segmented;

2) before the special-shaped steel frame is installed, firstly measuring the size of the end face of an upper step to be supported, taking the arch springing of the upper step falling on a rock stratum as a reference, and selecting an arch springing short section steel frame;

3) if a small amount of underexcavation exists, performing chiseling treatment by using a gun; if the overexcavation exists, square wood or section steel is adopted for compaction.

6. The non-explosive tunneling construction method for pilot holes in upper, soft and lower hard formation according to claim 1, wherein in step S4, the diameter of the control holes is between 70 and 80mm, and the net spacing between the control holes is between 20 and 30 cm.

7. The non-explosive excavation construction method of the pilot tunnel of the upper soft and lower hard formation according to claim 1, wherein the step S5 includes:

1) after the cantilever excavator is in place, cutting a groove from the bottom of a tunnel face along the horizontal direction, and reserving an excavation face of 0.8-1 m;

2) the cutting head of the cantilever excavator adopts top-down, left-right circular cutting;

3) 1-2 trusses of cantilever tunneling machine are advanced in each cycle, grid steel frames on two sides are firstly supported, and an inverted arch lags behind the tail of the cantilever tunneling machine by 3-5 m;

4) and loading the cut residue soil into a transport vehicle by a shovel plate part rake claw of the cantilever excavator, transporting the residue soil to a vertical shaft temporary residue soil pit, and lifting the residue soil pit out of the hole by a bridge crane.

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