WO2020259059A1

WO2020259059A1 - Tbm parallel heading tunnel trunk construction method

Info

Publication number: WO2020259059A1
Application number: PCT/CN2020/087187
Authority: WO
Inventors: 周建军; 李宏波; 张兵; 王发民; 陈桥; 王凯; 潘东江; 孙飞祥; 秦银平; 杨振兴; 吕乾乾
Original assignee: 中铁隧道局集团有限公司; 盾构及掘进技术国家重点实验室
Priority date: 2019-06-24
Filing date: 2020-04-27
Publication date: 2020-12-30
Also published as: CN110185457A; CN110185457B

Abstract

A TBM parallel heading tunnel trunk construction method. Parallel heading tunnel trunk construction comprises parallel heading station section construction, parallel heading TBM preparation tunnel, starting tunnel and receiving tunnel construction, and parallel heading TBM tunneling section construction. The parallel heading station section construction comprises tunnel portal shallow-buried section construction and IV-level surrounding rock bolt-shotcrete lining section construction. A three-step method is used for excavation in the tunnel portal shallow-buried section construction, and a two-step method is used for excavation in the IV-level surrounding rock bolt-shotcrete lining section construction. During the parallel heading TBM preparation tunnel, starting tunnel and receiving tunnel construction, a drilling and blasting method is used for construction, the three-step is used for excavation at V-level surrounding rocks, and a full-face tunneling method is used for excavation at III-level and IV-level surrounding rocks. Using different construction modes for different geology effectively shortens the construction period and improves the construction efficiency, and the designed construction method is adopted to ensure the safety of the construction process and the stability of the surrounding rocks.

Description

A construction method of TBM flat guide tunnel

Technical field

The invention relates to the technical field of tunnel construction, in particular to a construction method of a TBM flat guide tunnel body.

Background technique

In the construction of mountain tunnels, the TBM construction section of the main tunnel and the flat guide is usually open-type hard rock tunneling construction, using track transportation, belt conveyor ballasting, laying invert blocks, and the main tunnel and flat guide are synchronized for the second lining of the arch wall After the tunnel is penetrated, the machine will be dismantled in the tunnel. Due to the different situations encountered, the construction methods used will be different. In the construction part, it is necessary to pass through hard rock formations, weak rock formations or fractured layers, etc., and soft rock formations and lithological weaknesses are easily softened by groundwater and soft rock control occurs. Large deformation fracture layer or gravel layer is not easy to be disturbed too much. According to these terrains, different tunneling construction methods need to be designed.

Summary of the invention

In view of this, the purpose of the present invention is to address the shortcomings of the prior art and provide a TBM flat guide tunnel construction method with strong pertinence, high tunneling construction efficiency, high construction safety, and complete tunnel structure stability.

To achieve the above objective, the present invention adopts the following technical solutions:

A construction method of TBM flat guide tunnel body, which includes flat guide station section construction, flat guide TBM preparation tunnel, starting hole and receiving tunnel construction, and flat guide TBM tunneling section construction; the flat guide station section construction Including the construction of the shallow buried section of the entrance and the construction of the grade IV surrounding rock bolting and shotcrete lining section; the construction of the shallow buried section of the opening adopts the three-step method for excavation, and the construction of the grade IV surrounding rock bolted and shotcrete lining section uses the two step method for excavation; The drilling and blasting method is used for the construction of the horizontal guide TBM preparation tunnel, the starting hole and the receiving tunnel. The three-step method is used for excavation at the surrounding rock of grade V, and the full-face excavation method is used for the surrounding rock of grade III and IV. Excavation

The construction method of the flat-guided TBM tunneling section includes the following steps:

1) Advanced geological prediction: Use advanced instruments and methods such as TSP203, geological radar, advanced drilling, infrared water exploration, and geological sketching to conduct comprehensive advanced geological detection and prediction of the geological conditions within 30m in front of the construction head, and predict loose, For fracture zone conditions, comprehensive prediction and forecasting of the length, height, inclination angle and water volume of the fault using the geological sketch method;

2) Strengthen advanced support: use advanced pipe shed, advanced grouting, radial grouting, and strengthened support measures to strengthen the protection of the face; when the construction is prone to large deformation, the advanced small pipe grouting support method is used to advance Reinforce the surrounding rock; when encountering faulted sections, adopt the form of double liquid grout injection to quickly consolidate the crushed sections of surrounding rock; if the deformation is small, the radial bolts can be densely lengthened to improve the self-supporting capacity of the surrounding rock through pre-grouting Improve the stability of the surrounding rock to control the development of the plastic zone, and also set up small pipes or middle pipe sheds to strengthen the advance support, and at the same time use the dense steel frame for support;

3) Seepage water drainage: The rock mass within 30m in front of the head is a broken zone, and the groundwater from the exploration hole gushes out into strands. When the water pressure is ≥0.5MPa, the self-stabilization ability of the surrounding rock is judged to be better, and drainage and pressure reduction are performed. Afterwards, the support method is adopted to reinforce the surrounding rock; the self-stabilization ability of the surrounding rock is poor, and the medium is easily lost under the action of water, drainage and pressure reduction are performed, and then the surrounding rock is reinforced by grouting;

4) Initial support: The initial support consists of hanging steel mesh, sprayed concrete and anchor rods alone or in combination. The steel grille is added to strengthen the support within the 120° range of the Ⅲ and Ⅳ surrounding rock arches; the Ⅴ surrounding rock section The arch wall is reinforced with a grid steel frame; the anchor rods include mortar anchor rods and hollow anchor rods, the arch part uses grouting hollow anchor rods, and the remaining side walls use mortar anchor rods;

5) Invert construction: including invert excavation, initial spray concrete, installation of invert steel arch frame, final spray concrete, installation of waterproof and drainage pipes, invert lining steel reinforcement construction and invert backfill;

6) Track laying, drainage of equipment area, flat-guided TBM tunneling, and change step operation for the next cycle.

Preferably, the three-step method includes the following steps:

1) Measure and set out the line and implement advanced support;

2) Excavate the upper steps of the left pilot pit, and implement initial support and temporary support; excavate the lower steps of the left pilot pit, and implement initial support and temporary support, and monitor the surrounding rock at any time;

3) Excavation of the upper steps of the pilot pit on the right, and initial support and temporary support; excavation of the lower steps of the pilot pit on the right, and initial support and temporary support, and monitoring and measurement of surrounding rock at any time;

4) The upper steps in the middle section are excavated alternately from left to right and used for initial support; the middle steps in the middle section are excavated and used for initial support and temporary support; the lower steps in the middle section are excavated and used for initial support, and the enclosure shall be carried out at any time. Rock monitoring measurement;

5) Remove the temporary support of the two side walls at the bottom within 6-8m of the secondary lining, and pour the inverted arch and the inverted arch filled concrete;

6) Remove the remaining temporary supports and construct secondary lining.

Preferably, the two-step method includes the following steps:

1) Construction preparation, advanced geological forecast;

2) Blasting design, measuring and setting out;

3) Drill holes on the stairs, explosive blasting, ventilation and smoke exhaust;

4) Initial sprayed concrete;

5) Check the blasting effect, load and transport the ballast, adjust the blasting parameters when over-excavation occurs, and repeat steps 2)-4);

6) Up and down steps for initial support;

7) Monitor and measure, and strengthen support for those that do not meet the standards;

8) Excavation in the next cycle.

Preferably, the ventilation method in step 3) adopts press-in ventilation, and the fan of model SDF(B)-№11 is matched with a Φ1.6m air pipe to supply air to the face of the newly added main tunnel through the transverse channel.

Preferably, the length of the steps involved in the three-step method and the two-step method are both 5-6 m.

Preferably, the advanced pipe shed in step 2) is divided into the advanced large pipe shed and the advanced middle pipe shed, both of which are drilled by a down-the-hole drill and grouted by a grouting pump; the advanced large pipe shed adopts a diameter of φ108 and a thickness of 6mm The hot-rolled seamless steel pipe is processed, and each of the leading large pipe sheds is 35m long; the circumferential spacing between the leading large pipe sheds is 0.4m, and the insertion angle is 3°.

Preferably, the leading small conduit in step 2) is processed by hot-rolled seamless steel pipe with a diameter of φ42 and a thickness of 3.5mm, and each of the leading small conduits is 3.5m long; the arrangement of the small conduits is The circumferential spacing is 40cm, the overlapping length of the horizontal projection of two adjacent rows in the longitudinal direction is not less than 150cm, and the extrapolation angle is 5-10°.

Preferably, in step 6), three lines and four tracks are used for transportation during the tunneling of the flat-guide TBM, and a crossover switch is arranged every 3km in the tunnel, and the distance between the switch and the tunnel face is 3km.

The beneficial effects of the present invention are:

Advanced geological forecasting and a full understanding of the geological conditions of the tunnel to be excavated will help the construction team to make possible construction plans and pre-plans for the tunnels to be worked on, avoiding mud, water, and collapse during the construction process. The occurrence of controlled accidents is beneficial to increase the controllability of emergencies and ensure construction safety.

In the soft rock construction section, the advanced geological forecast can determine whether it is necessary to strengthen the advanced support and seepage drainage. The advanced support can reduce the disturbance to the surrounding rock, can effectively inhibit the occurrence and development of deformation, and increase the stability and construction of the tunnel Safety: Draining seepage water can reduce water volume and water pressure, avoid the loss of soft rock, and restrain the deformation of rock formations. In the hard rock construction section, there is no need for advance support and seepage drainage construction.

The initial support can effectively improve the stress condition of the structure, reduce the exposure and loosening of surrounding rocks, and is beneficial to the safety of the structure and construction.

By adopting different construction schemes for different geology, the invention effectively shortens the construction period, improves the construction efficiency, and guarantees the construction safety and the quality of the tunnel at the same time.

Detailed ways

The present invention will be further described below in conjunction with embodiments.

A construction method of TBM flat guide tunnel body, which includes flat guide station section construction, flat guide TBM preparation tunnel, starting hole and receiving tunnel construction, and flat guide TBM tunneling section construction; the flat guide station section construction Including the construction of the shallow buried section of the entrance and the construction of the grade IV surrounding rock bolting and shotcrete lining section; the construction of the shallow buried section of the opening adopts the three-step method for excavation, and the construction of the grade IV surrounding rock bolted and shotcrete lining section uses the two step method for excavation; The drilling and blasting method is used for the construction of the horizontal guide TBM preparation tunnel, the starting hole and the receiving tunnel. The three-step method is used for excavation at the surrounding rock of grade V, and the full-face excavation method is used for the surrounding rock of grade III and IV. Excavation; the length of the steps involved in the three-step method and the two-step method are both 5-6m.

The three-step method includes the following steps:

1) Measure and set out the line and implement advanced support;

6) Remove the remaining temporary supports and construct secondary lining.

The two-step method includes the following steps:

1) Construction preparation, advanced geological forecast;

2) Blasting design, measuring and setting out;

3) Drilling on the upper step, explosive blasting, ventilation and smoke exhaust; the ventilation method adopts press-in ventilation, and the fan of model SDF(B)-№11 is matched with a Φ1.6m air duct through the transverse channel to add a front hole The face is blown out.

4) Initial sprayed concrete;

6) Up and down steps for initial support;

8) Excavation in the next cycle.

The construction method of horizontally guided TBM tunnelling section in soft rock area includes the following steps:

1) Advanced geological prediction: Use advanced instruments and methods such as TSP203, ground penetrating radar, advanced drilling, infrared water exploration, and geological sketching to conduct comprehensive advanced geological detection and prediction of the geological conditions within 30m in front of the construction head, and predict loose, For fracture zone conditions, comprehensive prediction and forecasting of the length, height, inclination angle and water volume of the fault using the geological sketch method;

The construction method of horizontally guided TBM tunneling section in hard rock area includes the following steps:

1) Advanced geological prediction: Use advanced instruments and methods such as TSP203, ground penetrating radar, advanced drilling, infrared water exploration, geological sketch, etc. to conduct comprehensive advanced geological detection and prediction of the geological conditions within 30m in front of the construction head, and predict loose, For fracture zone conditions, comprehensive prediction and forecasting of the length, height, inclination angle and water volume of the fault using the geological sketch method;

2) Initial support: The initial support consists of hanging steel mesh, sprayed concrete and anchor rods alone or in combination. The steel grille is added to strengthen the support within the 120° range of grade III and IV surrounding rock arches; the section of grade V surrounding rock The arch wall is reinforced with a grid steel frame; the anchor rods include mortar anchor rods and hollow anchor rods, the arch part uses grouting hollow anchor rods, and the remaining side walls use mortar anchor rods;

3) Invert construction: including invert excavation, initial spray concrete, installation of invert steel arch frame, final spray concrete, installation of waterproof and drainage pipes, invert lining reinforcement construction and invert backfill;

4) Track laying, drainage of equipment area, flat-guided TBM tunneling, and stepping operation for the next cycle. Three lines and four tracks are used in the process of flat-guided TBM tunneling. A crossover switch is arranged every 3km in the tunnel, and the distance between the switch and the tunnel face is 3km.

To further explain the construction method of the tunneling section of the horizontal guide TBM:

In the process of strengthening the advanced support, the advanced pipe shed is divided into the advanced large pipe shed and the advanced middle pipe shed. Both use the down-the-hole drill to form the holes and the grouting pump is used for grouting; the advanced large pipe shed adopts heat with a diameter of φ108 and a thickness of 6mm. It is made of rolled seamless steel pipes, and each of the leading large pipe sheds is 35m long; the circumferential distance between the leading large pipe sheds is 0.4m, and the insertion angle is 3°. The leading small pipes are processed by hot-rolled seamless steel pipes with a diameter of φ42 and a thickness of 3.5mm, and each of the leading small pipes is 3.5m long; the arrangement of the small pipes is a circumferential spacing of 40cm, which is longitudinally adjacent The overlapping length of the two rows of horizontal projection is not less than 150cm, and the extrapolation angle is 5-10°.

The construction process of the advanced large pipe shed includes the following steps: construction preparation → drilling → hole cleaning → jacking into the steel pipe shed → hole cleaning → grouting operation.

Construction preparations: firstly make a concrete guide wall during construction. The structural size of the guide wall is 1m (height) * 1m (width), and the guide pipe is embedded in the wall. The guide pipe of the tunnel is made of Φ133mm steel pipe.

Drilling and clearing: Plan ahead for the pipe shed drilling platform before excavating the original topography of the cave entrance, and reserve stepped soil according to the plan during the excavation process as the pipe shed drilling platform; guide the hole pipe reserved in the wall Positioning and orientation, strictly control the lifting amount and angle of the drilling hole; use the pipe-shed DTH drilling rig to drill the hole by the air-driven dry drilling method, and the drilling parameters such as the diameter of the drill bit, the weight on bit, the speed, the air volume, and the air pressure, etc. Meet construction needs.

Jacking into the steel pipe shed: After the drilling test is qualified, the steel flower tube is continuously connected to the length, and the drill is rotated to push it into the hole. The steel pipe is welded with a grooved mouth. The length of the grooved mouth is 5cm and the height is the pipe diameter. half. In order to stagger the joints of the steel pipes, the first section of the pipe is arranged alternately with 3m and 6m, the first section with an odd number of holes uses a 3m long steel pipe, and the first section with an even number of holes uses a 6m long steel pipe. Use 6m long steel pipe. The steel pipe is jacked by a drilling rig, the single hole is jacked into the holed steel pipe, and the double hole is jacked into the non-porous steel tube.

Grouting operation: The full-hole press-in type is used to inject cement mortar into the large pipe shed, and the grouting pump is used to grouting according to the principle of first down and then up, first thinning and then thickening. The amount of grouting is controlled by pressure, the initial pressure of grouting is 0.5～1.0MPa, and the final pressure is 2.0MPa. After reaching the end mark, stop grouting. After the grouting is completed, the slurry in the pipe should be cleared in time, and the same grade cement mortar or C20 concrete should be used to fill it tightly to enhance the rigidity and strength of the pipe shed.

The fault zone and the broken surrounding rock section in the cave adopt the advanced support middle tube shed, and the advanced support middle tube shed adopts Ф60 and Ф50 grouting pipes. The pipe is filled with cement mortar. The process flow has no guiding wall construction procedures. Other construction techniques and large The pipe shed construction process is the same.

The construction process of the advanced small pipe includes the following steps: construction preparation → drilling → hole cleaning → installation of steel cannula → hole cleaning → grouting operation.

The leading small pipes are processed by hot-rolled seamless steel pipes with a diameter of φ42 and a thickness of 3.5mm, and each of the leading small pipes is 3.5m long; the arrangement of the small pipes is a circumferential spacing of 40cm, which is longitudinally adjacent The overlapping length of the two rows of horizontal projection is not less than 150cm, and the extrapolation angle is 5-10°.

The front end of the leading small pipe is processed into a cone to facilitate insertion and to prevent the grout from rushing forward. Drill a φ10mm grouting hole in the middle of the small pipe. The grouting holes are arranged in a plum blossom shape (to prevent dead corners from grouting), with a distance of 15mm, and the tail Do not drill holes within 1m to prevent grout leakage, and weld ring stirrups with a diameter of 6mm at the end to prevent the end from cracking when a small pipe is installed, which affects the connection of the grouting pipe.

The installation method of the advanced small pipe: use the air rock drill to drill the hole at the predetermined position, insert the pipe into the hole, wear the threaded protective cap, and insert the special head to the required depth to fully squeeze the hemp thread plunger and the hole wall. . Then fill the orifice with CS mortar, and the exposed length of the grouting pipe is 30cm to connect the orifice valve and pipeline.

The slurry used for the grouting of the leading small conduit is cement slurry with a water-cement ratio of 1:0.8-1.1 (weight ratio), which is selected by the laboratory during construction, and cement with a strength of not less than 42.5 is used.

The design of the grouting amount of the leading small duct:

The grouting pressure is 0.5~1Mpa, and the single-hole grout injection quantity Q is related to the porosity of the surrounding rock. It is estimated based on the diffusion radius and the cracks of the rock formation, and its value is:

Q=πR ² Lη(m ³ )

In the formula: R-slurry diffusion radius (m);

L—the length of grouting section (m);

η-the porosity of the rock formation, 40% for sand, 20% for clay, 5% for fractured zone.

The construction process of the initial support is to spray the concrete first, then lay the steel mesh, then drill the radial anchor rod, and then re-spray the concrete to the design thickness.

The spray concrete support construction procedure is: advanced geological forecast → excavation → initial spray concrete 4cm → construction setting out → installation of steel frame and hanging steel net → monitoring → application of system anchor rod → spraying to the design thickness.

The construction procedure of mortar anchor rod is: firstly locate and prepare for construction, use the anchor rod trolley or pneumatic rock drill to drill the anchor hole, after drilling the anchor hole, use high-pressure air to blow the rock debris in the anchor hole and check the depth of the anchor hole , And then send the anchor rod containing the anchor rod guide frame into the anchor hole, and reach the bottom of the anchor hole, and pay attention to rotating the mortar anchor rod, so that the end of the mortar anchor rod exposes the anchor hole 10cm, so as to weld with the steel mesh; Install the stop plug at the anchor hole at the end of the mortar anchor rod, and then use the grouting pipe to connect the end of the mortar anchor rod with the grouting pump for the mortar anchor rod. The arches and side walls are grouted by the double-pipe exhaust method. A soft plastic exhaust pipe with an inner diameter of Φ4～5mm and a wall thickness of 1～1.5mm is fed into the borehole with the anchor rod to the bottom of the hole, leaving a surplus length of about 1m outside the hole, and then fix the grouting pipe at the anchor hole After confirming that the exhaust pipe is unblocked, start to inject the mortar until the exhaust pipe is not exhausted or the slurry overflows, and then pull out the exhaust pipe. Install the pad after the mortar reaches the strength Tighten the nut on the plate. The water-cement ratio of the slurry used for grouting is 1:0.8-1.1 by weight, and the strength of the cement is not less than 42.5.

Hollow bolt construction drilling uses bolting trolleys or pneumatic rock drills. Before drilling, determine the hole position according to the design requirements. The drilling is straight and perpendicular to the structural surface of the rock at the location. The drilling diameter is φ42mm, and the drilling depth 10cm longer than the design length of the bolt. The hollow grouting anchor construction procedure is: after drilling the hole, blow the cuttings in the hole with high pressure wind; combine the anchor head and the end of the anchor rod, wear gaskets and nuts; send the combined rod body into the hole and reach Bottom of the hole; penetrate the end of the anchor rod to level the hole and fasten it to the rod; make sure that the hole is filled with grout during grouting, and the grouting pressure meets the design or specification requirements, and when the exhaust pipe overflows with thick grout Stop grouting; after the strength of the slurry reaches 70%, put an arched backing plate on the end of the anchor rod, and then tighten the nut according to the specified torque. The water-cement ratio of the slurry used for grouting is 1:0.4-0.5 by weight, the grouting pressure is 0.3-0.8MPa, and the cement slurry is used as it is mixed.

The grille steel frame is formed according to the design on the outside of the hole, and the hole is installed after the initial sprayed concrete, and welded with the anchor rod. Longitudinal connecting ribs are set between the grille steel frames, and the space between the grille steel frames is filled with spray concrete. The arch feet of the grille steel frame are placed on a solid foundation. When erected, they are perpendicular to the center line of the tunnel. When the gap is too large, set a spacer and fill it with spray concrete.

The spraying of concrete is completed in two times, namely, initial spraying and re-spraying. The sprayed concrete is mainly wet spraying, and the tidal spraying process is used for areas with large water content. The spray material is mixed by the concrete mixing station outside the cave and transported by the concrete conveyor. The thickness of the first sprayed concrete is 4~5cm, and the surrounding rock can be sealed quickly. The drilling and blasting section uses a wheeled wet spraying manipulator, and the TBM tunneling section uses the TBM's own wet spraying manipulator. The re-spraying shall be carried out after the arch frame, net hanging and anchor rod operations are completed. The wet spraying process is adopted and the spraying manipulator is used for construction.

The spraying concrete is carried out in segments, slices, and layers, from bottom to top, from no water, less water to water, more water areas, and pipes are placed in many water locations to drain the water. When spraying, the nozzle is basically perpendicular to the sprayed surface, and the distance is maintained at 1.5～2.0m. In the case of grille steel frame and steel arch frame, the gap between the steel frame and the rock surface is filled with sprayed concrete. The spraying sequence is symmetrical first down and then up. The gap between the steel frame and the surrounding rock is sprayed first, and then the steel frame is sprayed. In between, the steel frame should be covered by sprayed concrete, and the protective layer should not be less than 4cm. Before spraying, level the recesses of the sprayed surface, and then move the spray nozzle slowly and evenly in a spiral shape, pressing the front half of each circle, the diameter of the circle is about 30cm, and strive to spray the concrete surface smoothly. The thickness of one shot is controlled below 6cm, and the length of each section does not exceed 6m.

The treatment plan adopted when TBM excavates the fault fracture zone:

1) In order to enable TBM to pass through the fracture zone safely and smoothly during construction, advance geological forecasting is strengthened during construction, and the location, scale and water distribution of the fracture zone can be detected in time so that countermeasures can be taken early in the construction.

2) When the scale of the fault fracture zone is small, the method of low speed, low thrust, and steady excavation shall be adopted directly. After the surrounding rock is exposed, the shield shall be hung with steel mesh, anchor rods, sprayed concrete closed, and the steel frame shall be erected according to the actual situation. , To reduce downtime, prevent the formation of deformation and the TBM cutter head from being stuck.

3) The scale of the fault fracture zone is medium-scale, and the collapse is more serious. When the TBM cannot pass through the direct excavation, a steel frame is erected, steel mesh is hung, and the hand-sprayed concrete system is used to spray concrete to the collapsed area to seal the surrounding rock in time to reduce the surrounding rock. Exposure time and form a support system as soon as possible, and if necessary, implement advanced support; if the surrounding rock above the shield collapses severely, the shield and the rear steel arch can be used to cover the U14 channel steel and steel plate to seal the collapsed cavity, and then grouting for consolidation The surrounding rock collapsed above the knot shield in order to reduce the amount of ballast dropped when continuing forward; for the more severely collapsed part of the support shoe, the concrete backfill was poured behind the steel frame, and the front of the broken zone was pre-reinforced by grouting The stratum is used to reduce or prevent the deformation of the surrounding rock, and then slowly tunnel through.

4) When the fault fracture zone is large in scale and accompanied by fissure water, the pre-injection chemical slurry is used to reinforce the stratum slowly and pass the plan. If it is unable to pass through, a circuitous pilot pit is used, and the fracture zone is excavated by drilling and blasting. TBM Step through the plan.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and spirit of the technical solutions of the present invention. The scope shall be included in the scope of the claims of the present invention.

Claims

A construction method of TBM flat guide tunnel, characterized in that, flat guide tunnel construction includes flat guide station section construction, flat guide TBM preparation tunnel, starting hole and receiving tunnel construction, and flat guide TBM tunneling section construction; The construction of the pilot station section includes the construction of the shallow buried section of the entrance and the construction of the grade IV surrounding rock bolting and shotcreting lining section; the construction of the shallow buried section of the tunnel opening adopts the three-step method for excavation, and the construction of the grade IV surrounding rock bolting and shotcreting lining section uses the two step method. Excavation; the drilling and blasting method is used for the construction of the horizontal guide TBM preparation tunnel, the starting tunnel and the receiving tunnel. The three-step method is used for excavation at the level V surrounding rock, and the full-scale method is used at the level III and IV surrounding rock. Excavation by section excavation;

The construction method of the flat-guided TBM tunneling section includes the following steps:

1) Advanced geological prediction: Use advanced instruments and methods such as TSP203, geological radar, advanced drilling, infrared water exploration, and geological sketching to conduct comprehensive advanced geological detection and prediction of the geological conditions within 30m in front of the construction head, and predict loose, For fracture zone conditions, comprehensive prediction and forecasting of the length, height, inclination angle and water volume of the fault using the geological sketch method;

2) Strengthen advanced support: use advanced pipe shed, advanced grouting, radial grouting, and strengthened support measures to strengthen the protection of the face; when the construction is prone to large deformation, the advanced small pipe grouting support method is used to advance Reinforce the surrounding rock; when encountering faulted sections, adopt the form of double liquid grout injection to quickly consolidate the crushed sections of surrounding rock; if the deformation is small, the radial bolts can be densely lengthened to improve the self-supporting capacity of the surrounding rock through pre-grouting Improve the stability of the surrounding rock to control the development of the plastic zone, and also set up small pipes or middle pipe sheds to strengthen the advance support, and at the same time use the dense steel frame for support;

3) Seepage water drainage: The rock mass within 30m in front of the head is a broken zone, and the groundwater from the exploration hole gushes out into strands. When the water pressure is ≥0.5MPa, the self-stabilization ability of the surrounding rock is judged to be better, and drainage and pressure reduction are performed. Afterwards, the support method is adopted to reinforce the surrounding rock; the self-stabilization ability of the surrounding rock is poor, and the medium is easily lost under the action of water, drainage and pressure reduction are performed, and then the surrounding rock is reinforced by grouting;

4) Initial support: The initial support consists of hanging steel mesh, sprayed concrete and anchor rods alone or in combination. The steel grille is added to strengthen the support within the 120° range of the Ⅲ and Ⅳ surrounding rock arches; the Ⅴ surrounding rock section The arch wall is reinforced with a grid steel frame; the anchor rods include mortar anchor rods and hollow anchor rods, the arch part uses grouting hollow anchor rods, and the remaining side walls use mortar anchor rods;

5) Invert construction: including invert excavation, initial spray concrete, installation of invert steel arch frame, final spray concrete, installation of waterproof and drainage pipes, invert lining steel reinforcement construction and invert backfill;

6) Track laying, drainage of equipment area, flat-guided TBM tunneling, and change step operation for the next cycle.
The TBM flat guide tunnel construction method according to claim 1, wherein the three-step method comprises the following steps:

1) Measure and set out the line and implement advanced support;

2) Excavate the upper steps of the left pilot pit, and implement initial support and temporary support; excavate the lower steps of the left pilot pit, and implement initial support and temporary support, and monitor the surrounding rock at any time;

3) Excavation of the upper steps of the pilot pit on the right, and initial support and temporary support; excavation of the lower steps of the pilot pit on the right, and initial support and temporary support, and monitoring and measurement of surrounding rock at any time;

4) The upper steps in the middle section are excavated alternately from left to right and used for initial support; the middle steps in the middle section are excavated and used for initial support and temporary support; the lower steps in the middle section are excavated and used for initial support, and the enclosure shall be carried out at any time. Rock monitoring measurement;

5) Remove the temporary support of the two side walls at the bottom within 6-8m of the secondary lining, and pour the inverted arch and the inverted arch filled concrete;

6) Remove the remaining temporary supports and construct secondary lining.
The TBM flat guide tunnel construction method according to claim 1, wherein the two-step method comprises the following steps:

1) Construction preparation, advanced geological forecast;

2) Blasting design, measuring and setting out;

3) Drill holes on the stairs, explosive blasting, ventilation and smoke exhaust;

4) Initial sprayed concrete;

5) Check the blasting effect, load and transport the ballast, adjust the blasting parameters when over-excavation occurs, and repeat steps 2)-4);

6) Up and down steps for initial support;

7) Monitor and measure, and strengthen support for those that do not meet the standards;

8) Excavation in the next cycle.
The construction method of the TBM flat guide tunnel body according to claim 3, characterized in that in step 3), the ventilation method is press-in ventilation, and the fan of model SDF(B)-№11 is matched with a Φ1.6m air duct Air is supplied to the face of the newly added main hole through the cross channel.
The TBM flat guide tunnel construction method according to claim 2 or 3, characterized in that the length of the steps involved in the three-step method and the two-step method are both 5-6m.
The construction method of the TBM flat guide tunnel body according to claim 1, wherein the advanced pipe shed in step 2) is divided into an advanced large pipe shed and an advanced middle pipe shed, both of which are formed by a down-the-hole drill and a grouting pump Grouting; the leading large pipe shed is processed by hot-rolled seamless steel pipe with a diameter of φ108 and a thickness of 6mm, and each of the leading large pipe sheds is 35m long; the circumferential spacing between the leading large pipe sheds is 0.4m, the extrapolation angle is 3°.
The construction method of the TBM flat guide tunnel body according to claim 1, wherein the leading small pipe in step 2) is processed by hot-rolled seamless steel pipe with a diameter of φ42 and a thickness of 3.5mm, and each The leading small duct is 3.5m long; the arrangement of the small ducts is a circular spacing of 40cm, the overlapping length of the horizontal projection of two adjacent rows in the longitudinal direction is not less than 150cm, and the extrapolation angle is 5-10°.
The construction method of the TBM flat guide tunnel body according to claim 1, characterized in that, in the process of tunneling of the flat guide TBM in step 6), three lines and four tracks are used for transportation, and a crossover switch is arranged every 3km in the tunnel. The distance to the tunnel face is 3km.