Mechanical combined tunneling construction method for space-limited originating well interval tunnel

Abstract

The invention relates to a space-limited originating shaft interval tunnel mechanical combination tunneling construction method, which comprises the following steps of: 1, formulating a construction technical scheme according to the actual condition of a construction site; step 2, excavating a starting well and constructing a main body structure of the starting well; 3, excavation construction of the stepping hole in the tunnel is conducted; 4, shield / TBM ground facility construction is carried out; and 5, constructing and installing an expansion section of the shield launching reaction frame and the like. The construction method has the advantages that the interval tunnel adopts the combined tunneling mode of the hydraulic breaking hammer modified by the large and small arms, the shield tunneling machine and the TBM, the problems that the site construction condition is limited and the geological condition is complex can be effectively solved, TBM construction is carried out after the shield tunnel is communicated, a matched trolley behind TBM equipment is stored in the shield tunnel, and the construction efficiency is improved. The situation that most of rear matched trolleys are placed on the ground for large split starting, equipment is completely assembled in a well at a time, small split starting is carried out in a hole is avoided, shield / TBM refitting is reduced, and the tunnel construction progress is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a mechanical combined tunneling construction method for a starting shaft interval with limited space. Background Art

[0002] In urban subway construction, long and large interval tunnels are generally equipped with central ventilation shafts and construction starting shafts to solve permanent ventilation problems and construction organization problems. However, interval tunnels are often restricted by environmental conditions and the complexity of hydrogeology and engineering geology. In addition, the management of pyrotechnics in urban construction is becoming more and more stringent. Many cities have banned blasting operations, and rock excavation operations have become more difficult. There are fewer and fewer engineering projects that can be completed using a single method. In order to complete engineering projects quickly, safely and smoothly, it is necessary to study the combination of multiple methods. Especially in shield / TBM mechanical excavation, the geological conditions are often complex, requiring accurate equipment selection. At the same time, due to the limited construction site of the starting shaft of the interval tunnel, it is necessary to study and adopt appropriate methods to meet the requirements of mechanical excavation.

[0003] In the disclosed invention patent application documents, for example, the Chinese invention patent application No. 201910371980.9 discloses a tunnel construction method and a tunnel structure. The tunnel trajectory includes a straight segment and a non-straight segment connected to the straight segment. A receiving shaft is constructed at the end of the non-straight segment of the tunnel trajectory away from the straight segment, and a starting shaft is constructed at the end of the tunnel trajectory away from the receiving shaft. A tunnel boring machine is arranged in the starting shaft, and the straight segment is excavated along the tunnel trajectory to form a top pipe tunnel. Since the tunnel boring machine has a fast excavation construction speed and reduced cost, it can effectively reduce the cost of the top pipe tunnel and increase the excavation speed of the top pipe tunnel. The mining method is used to excavate the non-straight segment along the tunnel trajectory from the receiving shaft to form a mine tunnel, which effectively avoids the construction risk of long-distance excavation of the mining method. The top pipe tunnel and the mine tunnel are effectively connected through the joint tunnel to form a complete tunnel structure. The joint tunnel can achieve an effective transition between the top pipe tunnel and the mine tunnel.

[0004] For another example, the Chinese invention patent application number CN202210211699.0 discloses a method for construction of a variable tunnel section, including: constructing a first tunnel by a first tunnel boring machine; setting a first receiving well for receiving the first tunnel boring machine at the receiving position of the first tunnel; in the first receiving well, replacing the first tunnel boring machine with a second tunnel boring machine, the cross-sectional dimensions of the first tunnel boring machine and the second tunnel boring machine are different; converting the receiving well of the first tunnel boring machine into the starting well of the second tunnel boring machine; constructing a second tunnel by the second tunnel boring machine; setting a receiving well for receiving the second tunnel boring machine at the end position of the second tunnel. The functions of receiving and starting can be realized through the same working well, thereby achieving the purpose of reducing construction costs and improving construction efficiency. In addition, tunnel construction of different sections can be realized, which can effectively reduce construction costs compared to traditional integrated conversion equipment, and the construction method is simple and easy to operate.

[0005] For another example, Chinese invention patent application number CN201910721687.0 discloses a tunnel construction method, including: determining the location information of a tunnel to be constructed to obtain a first predetermined construction area for constructing the tunnel; obtaining the location information of facilities located at the first predetermined construction area; determining whether each facility causes location interference to the tunnel to be constructed or determining whether each facility poses a safety hazard, so as to demolish, relocate or provide protective reinforcement for the corresponding facilities; reinforcing the foundation of the first predetermined construction area; digging working wells at opposite ends of the first predetermined construction area, with the working well at one end of the first predetermined construction area serving as a starting well and the working well at the other end of the first predetermined construction area serving as a receiving well; and excavating earth from the starting well and the receiving well toward the middle of the first predetermined construction area at the same time until the tunnel is penetrated to form a tunnel.

[0006] The above disclosed invention patent applications have not solved the mechanical combined tunneling construction process method for the starting shaft interval tunnel with limited space. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention proposes a mechanical combined excavation construction method for a space-constrained starting shaft interval tunnel, the mechanical combined excavation construction method for a space-constrained starting shaft interval tunnel comprising the following steps:

[0008] Step 1: Develop a construction technical plan based on the actual conditions of the construction site, including the conditions of ground building facilities, the stratum lithology and geological structure of the construction site, the type of groundwater, the groundwater level and its fluctuation range, the distribution and combination relationship of aquifers and aquicludes, and the permeability of soil and rock layers;

[0009] Step 2: Excavation of the starting shaft and construction of the main structure of the starting shaft. After the construction of the foundation pit retaining structure is completed, use a breaker hammer to break and excavate the rock from top to bottom in layers, first break the middle to form an open surface, then break the surroundings, the layer height should not exceed 2m, and spray concrete support should be carried out in time. After the excavation is completed, the main structure bottom plate is constructed, the full-house scaffolding is set up, the steel bars are tied, the formwork is erected, and the side walls and ring frame beams of the main structure are constructed;

[0010] Step 3: excavation of the stepping hole in the tunnel. After the main structure of the starting shaft is completed, the horse head gate is broken with a breaker hammer to carry out the stepping hole construction. After the excavation is completed, a reinforced concrete arc guide platform is constructed;

[0011] Step 4: Shield / TBM ground facility construction;

[0012] Step 5, construct and install the enlarged section of the shield starting reaction frame;

[0013] Step 6: assembling and constructing the shield machine of the first tunnel;

[0014] Step 7: TBM assembly construction of the second tunnel;

[0015] Step 8, secondary lining of stepping hole.

[0016] Furthermore, the stepping hole excavation construction in the tunnel described in step 3 includes:

[0017] Step 3.1: The stepping hole is excavated using a heavy-duty breaker with a diameter of 190 mm or more, with a hammer striking frequency of 200 to 350 bpm and a large excavator with a counterweight of 40 tons or more. Since the penetration force of the breaker is related to the hammering energy of the power equipment piston, the model of the breaker needs to match the power of the equipment counterweight; in order to meet the needs of small-section excavation of the stepping hole, the large and small arms of the large excavator need to be modified, and the length of the large and small arms is shorter than that of the conventional excavator;

[0018] Step 3.2 The excavation length of the tunnel must meet the requirements of the shield equipment going down to the shaft. During the crushing operation, the middle and lower part of the face is crushed first. After the middle and lower part forms an open surface, a layer-by-layer peeling and crushing method is adopted, and then the two sides and the arch are crushed, and finally the lower part is crushed. The crushed rock debris is transported to the slag bucket of the starting shaft, and then vertically transported and unloaded into the slag pool by lifting equipment.

[0019] Step 3.3 When the operating space on both sides of the crushing face and the arch exceeds 2m, it is necessary to carry out initial support in time, install anchor rods, erect grid steel frames, hang steel mesh, and spray C25 concrete;

[0020] Step 3.4: The starting section of the shield tunnel is 8m long and has a circular section, the expanded section is 7m long and has a rectangular section, and the other sections are horseshoe sections; the starting section of the TBM tunnel is 13m long and has a circular section, and the other sections are horseshoe sections. The excavation length of the tunnel is not less than 45m in the direction of the first tunnel of the shield tunnel, and not less than 50m in the direction of the second tunnel of the TBM;

[0021] Step 3.5: Open a horse head gate at the entrance of the tunnel and connect 3 grids at the stress concentration point. When the excavation reaches the expansion end, advance the spacing length of 2 to 3 grids and expand outward at an outward angle of 30° to 45° to gradually form an expansion section.

[0022] Step 3.6: Make reinforced concrete curved guide platform:

[0023] In order to facilitate the smooth advancement of the shield / TBM shield to the heading face, after the excavation of the stepping tunnel is completed, the glass fiber reinforcement mesh is hung, the heading face is sealed with plain sprayed concrete, and a reinforced concrete arc guide platform is constructed. After measurement and layout, the smoothness of the guide platform is controlled according to the axis and horizontal elevation of the stepping tunnel tunnel, the steel bars are tied, the sliding rails are installed, and the rail brackets are welded under the rails with a spacing of 1.5m. The reaction seat positioning steel pipes with a diameter of 150mm are embedded on both sides of the rails with a spacing of 1.5-2m and a pre-embedded depth of 20-30cm. The formwork is erected and the concrete is poured.

[0024] Furthermore, the shield / TBM ground facilities described in step 4:

[0025] Step 4.1: construct gantry crane tracks on the ring beam of the enclosure structure and install two gantry cranes on the tracks;

[0026] Step 4.2 Install two box-type transformers in the originating well site;

[0027] Step 4.3: Install a mortar mixing station in the originating well site;

[0028] Step 4.4: Build a slag pit at one end of the starting shaft, and install a slag screening device next to the slag pit to separate the slag and realize the resource utilization of the slag;

[0029] Step 4.5: Install a pea gravel hopper on the top of the second tunnel entrance of the TBM. Install an automatic weighing system on the pea gravel hopper. The belt conveys the pea gravel horizontally to the vertical discharge pipe, which is connected to the flatbed truck hopper.

[0030] Furthermore, in step 5, the expansion section of the shield starting reaction frame installation is:

[0031] Step 5.1 Before the shield starts, cast the expansion section for the installation of the starting reaction frame of the shield. First, construct the bottom plate of the expansion section. The bottom plate and the arc guide platform of the stepping hole are constructed together. First, tie the bottom plate steel bars of the main structure of the expansion section, embed the positioning steel plates, and pour the bottom plate concrete. Then, set up the full house scaffolding to tie the arch wall steel bars, buckle the combined steel formwork, and pour the arch wall concrete. Pre-embed 4 positioning steel plates on both sides of the bottom plate. The first pair of steel plates are the reaction frame column base connectors, and the steel plate size is 900*600*20mm. The remaining 6 steel plates are the reaction frame diagonal brace connectors, and the steel plate size is 900*600*20mm. The longitudinal spacing of the steel plates is 1m and 1.5m respectively.

[0032] Step 5.2: 3 positioning steel plates are embedded in the arch position 2m behind the upper crossbeam of the reaction frame, and 1 positioning steel plate is embedded in the arch waist position on both sides of the upper crossbeam end. The size of the steel plate is 500*500*20mm. 4 steel bars are embedded under each steel plate. The length of the steel bar is 500mm, and a 25mm hook is set at the end. The steel bar and the steel plate are pierced and plug welded;

[0033] Step 5.3 The expanded arch wall adopts the Mantanghong scaffolding as the formwork support system, and a pre-bent arc arch frame is set up on the top support of the scaffolding. The combined steel formwork is laid on the arch frame. The longitudinal ribs of the combined steel formwork are retracted 1 to 2 mm to facilitate the outer arc to be round and smooth during assembly, and the template joints are tightly fitted;

[0034] Furthermore, in step 6, the first tunnel shield is assembled and the shield machine is in a normal excavation state:

[0035] Step 6.1 After the shield and the screw machine are assembled in the well, they are pushed forward to the starting guide tunnel. When pushing, steel rods are inserted into the pre-buried steel pipes, and steel beams and top irons are installed to provide reaction support for the shield push. Two jacks are fixed on the sliding rails, and a grease drag reduction layer is applied on the rails. The shield is pushed forward to the starting tunnel, and then the reaction frame is lowered into the well and transported to the expansion section for splicing and installation. When the reaction frame is spliced ​​and installed, the center line of the starting mileage section of the reaction frame position is first measured and marked on the side wall of the expansion section to facilitate the center positioning of the reaction frame. The reaction frame is positioned against the positioning plane of the 0 ring segment and is perpendicular to the tunnel axis here. The flatness and verticality allowable deviation is no more than 10mm to ensure the starting accuracy without negative rings. The starting process without negative rings is adopted, and there is no need to remove the negative ring segments.

[0036] Step 6.2 The bottom of the reaction frame column is welded to the reserved steel plate of the expansion section. The two ends of the upper and bottom beams are supported on the structural side walls and welded firmly to the positioning steel plates on the side walls. The front end of the upper beam is supported on the expanded section arch and the embedded steel plate of the side wall with steel pipe profiles and welded firmly. After the reaction frame is fixed, three diagonal braces on each side of the rear are welded. The diagonal braces are supported by steel pipe profiles.

[0037] Step 6.3 After the reaction frame is installed, the train marshaling, connecting bridge, No. 1 to 4 trolleys and temporary belt conveyor are lowered into the well. The temporary belt conveyor, connecting bridge, No. 1 to 4 trolleys and the shield are assembled. After the connecting bridge and No. 1 trolley are connected in the starting well, they are pushed into the starting tunnel together and connected to the shield. The other trolleys are connected section by section. The temporary belt slag outlet is set at the position of No. 4 trolley. The main facilities of No. 5 and No. 6 trolleys are spare air compressors, sewage tanks, and high-voltage cable reels. Trolleys No. 6 and No. 5 are lowered in turn. The well is first stored in the TBM stepping tunnel, and the pipeline length between trolleys No. 4 and 5 is extended by 40m. The main pipelines are cables, water pipes and air ducts. The pipeline extension uses a gate-shaped steel bracket and a hanging rail trolley installed on the side wall of the stepping tunnel. The line is extended as the shield machine steps forward. After the shield machine has excavated 40m and meets the length requirements of trolleys No. 5 to 6, the extended pipeline and temporary belt conveyor are removed, and then trolleys No. 5 and 6 are moved forward for assembly of the whole machine to form a normal excavation state until the first shield tunnel is penetrated.

[0038] Furthermore, the TBM second tunnel assembly construction in step 7:

[0039] Step 7.1 After the first shield tunnel is penetrated, the tunnel portal ring beam of the first shield tunnel shall be constructed in time, and the TBM equipment of the second tunnel shall be assembled at the same time. The TBM is in double shield excavation mode. When the TBM equipment is long and the step-in tunnel does not meet the requirements of one-time overall start-up, a small split start-up plan is adopted. The start-up is carried out after the assembly of the TBM host, connecting bridge, and trolleys 1 to 5 is completed. The secondary assembly begins when the excavation meets the conditions for the assembly of the TBM whole machine. In the case of split start-up, the host to trolley 5 are all assembled, and the temporary belt conveyor slag outlet is temporarily modified and placed on trolley 4. The space behind trolley 5 is used to hoist the pipe segments and temporary slag trucks. At this time, the train consists of only the pipe segment transport truck and the temporary slag truck. The pea gravel hopper is transported by a flatbed truck and shared with the pipe segment truck in the early stage. Due to the limited space behind trolley 5, the slag of the first 4 to 5 rings is not more than 2m 3 The slag bucket is discharged. When the space behind the No. 5 trolley meets the space for conventional slag bucket hoisting, the conventional 20m 3 The slag bucket is discharged. During the first start, the No. 6 to No. 13 trolleys are temporarily stored in the first shield tunnel, and the pipeline length between the No. 5 and No. 6 trolleys is extended by 110m. After the TBM tunnel has been excavated for 110m and the length of the step-in tunnel has been added, the whole machine can be placed for the second start, the extended pipeline and temporary belt conveyor are removed, and the slag outlet of the subsequent belt conveyor is restored to the No. 8 trolley, and the train formation is restored to normal;

[0040] Step 7.2 The extended pipeline is erected on the side wall of the shaft using a special pipeline gate steel support. The pipeline support consists of channel steel columns, beams, and rollers. The columns are anchored on the bottom plate of the shaft with a spacing of 1.2 to 1.5 m and a column height of 2.5 to 3 m. The remaining pipeline is suspended vertically between two groups of supports. Each group of supports can extend the line for 5 to 6 m, and rollers are set above the channel steel beams. After entering the stepping tunnel, the pipeline is extended using a hanging rail + trolley. The hanging rail is made of I-beams, which are welded under the corbels. The corbels are fixed to the side wall of the stepping tunnel with a spacing of 0.8 to 1 m. The trolley transport device is installed on the flange of the I-beam. The spacing of the trolley transport device is not more than 500 mm. The pipeline is suspended on the sling of the trolley transport device, which automatically slides forward with the TBM excavation. The first ring of segments is fixed and installed in the form of anchor legs + annular steel plates.

[0041] Step 7.3 Before the TBM starts, an annular steel plate is set at the end of the starting tunnel. The steel plate is connected to the brackets anchored by multiple anchor rods. The annular steel plate is supported and reinforced with steel sections at the bottom of the tunnel. The end is sealed with cement, and "L"-shaped angle steel and longitudinal arc bolt locking devices and segment sealing devices are installed to ensure that there is no leakage when backfilling and grouting behind the first ring of segments.

[0042] Furthermore, in step 7.3, one end of the "L"-shaped angle steel is in contact with the inner arc surface of the pipe segment, and the other end is welded to the annular steel plate as a whole, and the arc bolts are installed through the longitudinal bolt holes of the pipe segment to connect with the annular steel plate, and the back of the annular steel plate is supported on the wall of the stepping hole by a steel section;

[0043] Furthermore, in step 7.3, the segment sealing device is sealed between the segment and the annular steel plate with shield tail grease;

[0044] Furthermore, the secondary lining of the stepping hole in step 8:

[0045] The circular section of the stepping tunnel is lined by the shield / TBM empty-push assembly segment method. Before the start of the shield tunnel, the expanded section of the stepping tunnel is lined for the second time using the Mantanghong scaffolding support formwork system. After the second TBM tunnel is penetrated, the other sections of the stepping tunnel are lined for the second time using a full-section hydraulic lining trolley.

[0046] The superior technical effects of the present invention over the prior art in this technical field are:

[0047] 1. The mechanical combined excavation construction method for the space-constrained starting shaft interval tunnel described in the present invention adopts a combined excavation method of a hydraulic breaker modified with large and small arms, a shield machine, and a TBM, which can effectively solve the problems of limited on-site construction conditions and complex geological conditions. After the shield tunnel is penetrated, TBM construction is carried out, and the rear supporting trolleys of the TBM equipment are stored in the shield tunnel, avoiding the large-scale starting of most of the rear supporting trolleys on the ground. All the equipment is assembled in the shaft at one time, and small-scale starting is carried out in the cave, which reduces the modification of the shield / TBM and significantly improves the progress of tunnel construction.

[0048] 2. The mechanical combined excavation construction method for the space-constrained starting shaft interval tunnel described in the present invention optimizes the length of the step-in hole, which can not only reduce the cost of heavy-duty breaker crushing, but also avoid the large-scale split starting of shield and TBM equipment, and significantly reduce the cost of extending the split starting pipeline and the cost of equipment modification.

[0049] 3. The mechanical combined excavation construction method for the space-constrained starting shaft interval tunnel described in the present invention adopts the negative ring-free starting technology for the shield / TBM starting hole, fully utilizes the construction process combining permanent and temporary, avoids the waste of negative ring removal, reduces the safety risk of negative ring removal, and saves the cost of negative ring removal.

[0050] 4. In the mechanical combined excavation construction method for the space-constrained starting shaft interval tunnel described in the present invention, the shield / TBM split starting pipeline extension adopts special brackets and hanging rails to automatically move forward with the mechanical excavation, which effectively improves the construction efficiency, reduces the breakage, damage and leakage caused by manual dragging of the pipeline, and ensures the normal excavation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the flow chart of the mechanical combined excavation construction method for a tunnel between a starting shaft and a space-constrained area according to the present invention. DETAILED DESCRIPTION

[0052] The mechanical combined tunneling construction method for a space-constrained starting shaft interval tunnel of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods of the specification.

[0053] Example

[0054] The mechanical combined tunneling construction method for the space-limited starting shaft interval tunnel is as follows: Figure 1 As shown, the specific implementation process is as follows:

[0055] Step 1: Develop a construction technical plan based on the actual conditions of the construction site, including the conditions of ground building facilities, the stratum lithology and geological structure of the construction site, the type of groundwater, the groundwater level and its fluctuation range, the distribution and combination relationship of aquifers and aquicludes, and the permeability of soil and rock layers;

[0056] Step 2: Excavation of the starting shaft and construction of the main structure of the starting shaft. After the construction of the foundation pit retaining structure is completed, use a breaker hammer to break and excavate the rock from top to bottom in layers, first break the middle to form an open surface, then break the surroundings, the layer height should not exceed 2m, and spray concrete support should be carried out in time. After the excavation is completed, the main structure bottom plate is constructed, the full-house scaffolding is set up, the steel bars are tied, the formwork is erected, and the side walls and ring frame beams of the main structure are constructed;

[0057] Step 3: Excavation of the stepping hole in the tunnel is as follows:

[0058] After the main structure of the starting shaft is completed, the horse head gate is broken with a breaker, and after the excavation of the stepping hole is completed, a reinforced concrete arc guide platform is constructed: Specifically, step 3.1 The stepping hole is excavated using a heavy breaker with a diameter of 190mm or more, and the breaker hammer strike frequency is 200-350bpm. A large excavator with a counterweight of more than 40 tons is used. In view of the fact that the penetration force of the breaker hammer is related to the hammering energy of the power equipment piston, the model of the breaker hammer needs to match the power of the equipment counterweight; in order to meet the needs of small-section excavation of the stepping hole, the large and small arms of the large excavator need to be modified, and the length of the large and small arms is shorter than that of the conventional excavator;

[0059] Step 3.2 The excavation length of the tunnel must meet the requirements of the shield equipment going down to the shaft. During the crushing operation, the middle and lower parts of the face are crushed first. After the middle and lower parts form an open surface, the layers are crushed by peeling, and then the two sides and the arch are crushed. Finally, the lower part is crushed. The crushed rock slag is transported to the slag bucket of the starting shaft, and then vertically transported and unloaded into the slag pool by hoisting equipment;

[0060] Step 3.3 When the operating space on both sides of the crushing face and the arch exceeds 2m, it is necessary to carry out initial support in time, install anchor rods, erect grid steel frames, hang steel mesh, and spray C25 concrete;

[0061] Step 3.4: The starting section of the shield tunnel is 8m long and has a circular section, the expanded section is 7m long and has a rectangular section, and the other sections are horseshoe sections; the starting section of the TBM tunnel is 13m long and has a circular section, and the other sections are horseshoe sections. The excavation length of the tunnel is not less than 45m in the direction of the first tunnel of the shield tunnel, and not less than 50m in the direction of the second tunnel of the TBM;

[0062] Step 3.5: Open a horse head gate at the entrance of the tunnel and connect 3 grids at the stress concentration point. When the excavation is broken to the expansion end, advance the spacing length of 2 to 3 grids and expand outward at an outward angle of 30° to 45° to gradually form an expansion section;

[0063] Step 3.6, construct the reinforced concrete arc guide platform:

[0064] To facilitate the smooth advancement of the shield / TBM shield to the face, after the excavation of the stepping tunnel is completed, a glass fiber reinforcement mesh is hung, the face is sealed with plain sprayed concrete, and a reinforced concrete arc guide platform is constructed. After measuring and laying out, the smoothness of the guide platform is controlled according to the axis and horizontal elevation of the stepping tunnel tunnel, the steel bars are tied, the sliding rails are installed, and the rail brackets are welded under the rails with a spacing of 1.5m. The reaction seat positioning steel pipes with a diameter of 150mm are embedded on both sides of the rails with a spacing of 1.5-2m and an embedded depth of 20-30cm. The formwork is erected and the concrete is poured;

[0065] Step 4: Shield / TBM ground facility construction, the specific construction is as follows:

[0066] Step 4.1: construct gantry crane tracks on the ring beam of the enclosure structure and install two gantry cranes on the tracks;

[0067] Step 4.2 Install two box-type transformers in the originating well site;

[0068] Step 4.3: Install a mortar mixing station in the originating well site;

[0069] Step 4.4: Build a slag pit at one end of the starting shaft, and install a slag screening device next to the slag pit to separate the slag and realize the resource utilization of the slag;

[0070] Step 4.5: Install a pea gravel hopper on the top of the second tunnel entrance of the TBM. Install an automatic weighing system on the pea gravel hopper. The belt conveys the pea gravel horizontally to the vertical discharge pipe, which is connected to the flatbed truck hopper.

[0071] Step 5: construct and install the enlarged section of the shield starting reaction frame. The specific construction is as follows:

[0072] Step 5.1 Before the shield starts, cast the expansion section for the installation of the starting reaction frame of the shield. First, construct the bottom plate of the expansion section. The bottom plate and the arc guide platform of the stepping hole are constructed together. First, tie the bottom plate steel bars of the main structure of the expansion section, embed the positioning steel plates, and pour the bottom plate concrete. Then, set up the full house scaffolding to tie the arch wall steel bars, buckle the combined steel formwork, and pour the arch wall concrete. Pre-embed 4 positioning steel plates on both sides of the bottom plate. The first pair of steel plates are the reaction frame column base connectors, and the steel plate size is 900*600*20mm. The remaining 6 steel plates are the reaction frame diagonal brace connectors, and the steel plate size is 900*600*20mm. The longitudinal spacing of the steel plates is 1m and 1.5m respectively.

[0073] Step 5.2: 3 positioning steel plates are embedded in the arch position 2m behind the upper crossbeam of the reaction frame, and 1 positioning steel plate is embedded in the arch waist position on both sides of the upper crossbeam end. The size of the steel plate is 500*500*20mm. 4 steel bars are embedded under each steel plate. The length of the steel bar is 500mm, and a 25mm hook is set at the end. The steel bar and the steel plate are pierced and plug welded;

[0074] Step 5.3 The expanded arch wall adopts the Mantanghong scaffolding as the formwork support system, and a pre-bent arc arch frame is set up on the top support of the scaffolding. The combined steel formwork is laid on the arch frame. The longitudinal ribs of the combined steel formwork are retracted 1 to 2 mm to facilitate the outer arc to be round and smooth during assembly, and the template joints are tightly fitted;

[0075] Step 6: The shield machine of the first tunnel is assembled and constructed, and the shield machine is in normal excavation state. The specific construction is as follows:

[0076] Step 6.1 After the shield and the screw machine are assembled in the well, they are pushed forward to the starting guide tunnel. When pushing, steel rods are inserted into the pre-buried steel pipes, and steel beams and top irons are installed to provide reaction support for the shield push. Two jacks are fixed on the sliding rails, and a grease drag reduction layer is applied on the rails. The shield is pushed forward to the starting tunnel, and then the reaction frame is lowered into the well and transported to the expansion section for splicing and installation. When the reaction frame is spliced ​​and installed, the center line of the starting mileage section of the reaction frame position is first measured and marked on the side wall of the expansion section to facilitate the center positioning of the reaction frame. The reaction frame is positioned against the positioning plane of the 0 ring segment and is perpendicular to the tunnel axis here. The flatness and verticality allowable deviation is no more than 10mm to ensure the starting accuracy without negative rings. The starting process without negative rings is adopted, and there is no need to remove the negative ring segments.

[0077] Step 6.2 The bottom of the reaction frame column is welded to the reserved steel plate of the expansion section. The two ends of the upper and bottom beams are supported on the structural side walls and welded firmly to the positioning steel plates on the side walls. The front end of the upper beam is supported on the expanded section arch and the embedded steel plate of the side wall with steel pipe profiles and welded firmly. After the reaction frame is fixed, three diagonal braces on each side of the rear are welded. The diagonal braces are supported by steel pipe profiles.

[0078] Step 6.3 After the reaction frame is installed, the train marshaling, connecting bridge, No. 1 to 4 trolleys and temporary belt conveyor are lowered into the well. The temporary belt conveyor, connecting bridge, No. 1 to 4 trolleys and the shield are assembled. After the connecting bridge and No. 1 trolley are connected in the starting well, they are pushed into the starting tunnel together and connected to the shield. The other trolleys are connected section by section. The temporary belt slag outlet is set at the position of No. 4 trolley. The main facilities of No. 5 and No. 6 trolleys are spare air compressors, sewage tanks, and high-voltage cable reels. Trolleys No. 6 and 5 They are lowered into the well in sequence and first stored in the TBM stepping tunnel. The pipeline between trolleys 4 and 5 is extended by 40m. The main pipelines are cables, water pipes and air ducts. The pipeline extension adopts a gate-shaped steel bracket and a hanging rail trolley installed on the side wall of the stepping tunnel. It is lowered with the stepping of the shield machine. After the shield machine excavates 40m and meets the length requirements of trolleys 5 and 6, the extended pipeline and temporary belt conveyor are removed, and then trolleys 5 and 6 are moved forward for complete machine assembly to form a normal excavation state until the first shield tunnel is broken through;

[0079] Step 7: Second tunnel TBM assembly construction, the specific construction is as follows:

[0080] Step 7.1 After the first shield tunnel is penetrated, the portal ring beam of the first shield tunnel shall be constructed in time, and the TBM equipment of the second tunnel shall be assembled at the same time. The TBM is in double shield excavation mode. When the TBM equipment is long and the step-in tunnel does not meet the requirements of one-time overall start-up, a small split start-up plan is adopted. The start-up is carried out after the assembly of the TBM host, connecting bridge, and trolleys 1-5 is completed. The secondary assembly begins when the excavation meets the conditions for the assembly of the TBM whole machine. In the case of split start-up, the host to trolley 5 is fully assembled, and the temporary belt conveyor slag outlet is temporarily modified and placed on trolley 4. The space behind trolley 5 is used to hoist the pipe segments and temporary slag trucks. At this time, the train consists of only pipe segment transport trucks and temporary slag trucks. The pea gravel hopper is transported by flatbed trucks and shared with the pipe segment trucks in the early stage. Due to the limited space behind trolley 5, the excavation slag of the first 4 to 5 rings is not more than 2m 3 The slag bucket is discharged. When the space behind the No. 5 trolley meets the space for conventional slag bucket hoisting, the conventional 20m 3 The slag bucket is discharged. During the first start, the No. 6 to No. 13 trolleys are temporarily stored in the first shield tunnel, and the pipeline length between the No. 5 and No. 6 trolleys is extended by 110m. After the TBM tunnel has been excavated for 110m and the length of the step-in tunnel has been added, the whole machine can be placed for the second start, the extended pipeline and temporary belt conveyor are removed, and the slag outlet of the subsequent belt conveyor is restored to the No. 8 trolley, and the train formation is restored to normal;

[0081] Step 7.2 The extended pipeline is erected on the side wall of the shaft using a special pipeline gate steel support. The pipeline support consists of channel steel columns, beams, and rollers. The columns are anchored on the bottom plate of the shaft with a spacing of 1.2 to 1.5 m and a height of 2.5 to 3 m. The remaining pipeline is vertically suspended between two groups of supports. Each group of supports can extend the line by 5 to 6 m, and the rollers are set above the channel steel beams. After entering the stepping tunnel, the pipeline is extended using a hanging rail + trolley. The hanging rail is made of I-beams, which are welded under the corbels. The corbels are fixed to the side wall of the stepping tunnel with a spacing of 0.8 to 1 m. The trolley transport device is installed on the flange of the I-beam. The spacing of the trolley transport device is not more than 500 mm. The pipeline is suspended on the sling of the trolley transport device, which automatically slides forward with the TBM excavation. The first ring segment is fixed in the form of anchor legs + annular steel plates.

[0082] Step 7.3 Before the TBM starts, an annular steel plate is set at the end of the starting tunnel. The steel plate is connected to the brackets anchored by multiple anchor rods. The annular steel plate is supported and reinforced with steel sections at the bottom of the tunnel. The end is sealed with cement, and an "L"-shaped angle steel and a longitudinal arc bolt locking device and a segment sealing device are installed to ensure that there is no leakage when backfilling and grouting behind the first ring segment.

[0083] Step 8, secondary lining of the stepping tunnel. The circular section of the stepping tunnel is lined with the shield / TBM empty push assembly segment method. Before the start of the shield tunneling, the expanded section of the stepping tunnel is lined with the Mantanghong scaffolding support formwork system. After the TBM tunnel is penetrated, the other sections of the stepping tunnel will be lined with the full-section hydraulic lining trolley.

[0084] In a specific embodiment of the present invention, in step 7.3, one end of the "L"-shaped angle steel is in contact with the inner arc surface of the pipe segment, and the other end is welded to the annular steel plate as a whole. The arc bolts are installed through the longitudinal bolt holes of the pipe segment to connect with the annular steel plate, and the back of the annular steel plate is supported on the wall of the stepping hole by steel sections.

[0085] In a specific embodiment of the present invention, in step 7.3, the segment sealing device is provided with a sealing layer of shield tail grease between the segment and the annular steel plate;

[0086] The above description is only a preferred embodiment of the present invention and does not limit the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A mechanical combined tunneling construction method for a space-constrained starting shaft interval tunnel, comprising the following steps: Step 1: Develop a construction technical plan based on the actual conditions of the construction site, including the conditions of ground building facilities, the stratum lithology and geological structure of the construction site, the type of groundwater, the groundwater level and its fluctuation range, the distribution and combination relationship of aquifers and aquicludes, and the permeability of soil and rock layers; Step 2: Excavation of the starting shaft and construction of the main structure of the starting shaft. After the construction of the foundation pit retaining structure is completed, use a breaker hammer to break and excavate the rock from top to bottom in layers, first break the middle to form an open surface, then break the surroundings, the layer height should not exceed 2m, and spray concrete support should be carried out in time. After the excavation is completed, the main structure bottom plate is constructed, the full-house scaffolding is set up, the steel bars are tied, the formwork is erected, and the side walls and ring frame beams of the main structure are constructed; Step 3: excavation of the stepping hole in the tunnel. After the main structure of the starting shaft is completed, the horse head gate is broken with a breaker hammer to carry out the stepping hole construction. After the excavation is completed, a reinforced concrete arc guide platform is constructed; Step 4: Shield / TBM ground facility construction; Step 5, construct and install the enlarged section of the shield starting reaction frame; Step 6: assembling and constructing the shield machine of the first tunnel; Step 7: TBM assembly construction of the second tunnel; Step 8, secondary lining of stepping hole.

2. According to the mechanical combined tunneling construction method for the space-constrained starting shaft interval of claim 1, the step-by-step tunnel excavation construction in step 3 comprises: Step 3.1: The stepping hole is excavated using a heavy-duty breaker with a diameter of 190 mm or more. The breaker frequency is 200-350 bpm, and the counterweight is 40 tons or more. The breaker model is matched with the counterweight power of the equipment, given that the penetration force of the breaker is related to the hammer energy of the power equipment piston. To meet the needs of small-section excavation of stepping holes, the large and small arms of the large excavator need to be modified, and the length of the large and small arms is shorter than that of conventional excavators. Step 3.2 The excavation length of the tunnel must meet the requirements of the shield equipment going down to the shaft. During the crushing operation, the middle and lower parts of the face are crushed first. After the middle and lower parts form an open surface, the layers are crushed by peeling, and then the two sides and the arch are crushed. Finally, the lower part is crushed. The crushed rock slag is transported to the slag bucket of the starting shaft, and then vertically transported and unloaded into the slag pool by hoisting equipment; Step 3.3 When the operating space on both sides of the crushing face and the arch exceeds 2m, it is necessary to carry out initial support in time, install anchor rods, erect grid steel frames, hang steel mesh, and spray C25 concrete; Step 3.4: The starting section of the shield tunnel is 8m long and has a circular section, the expanded section is 7m long and has a rectangular section, and the other sections are all horseshoe sections; the starting section of the TBM tunnel is 13m long and has a circular section, and the other sections are all horseshoe sections. The excavation length of the tunnel is not less than 45m in the direction of the first tunnel of the shield tunnel, and not less than 50m in the direction of the second tunnel of the TBM; Step 3.5: Open a horse head gate at the entrance of the tunnel and connect 3 grids at the stress concentration point. When the excavation is broken to the expansion end, advance the spacing length of 2 to 3 grids and expand outward at an outward angle of 30° to 45° to gradually form an expansion section; Step 3.6: Make reinforced concrete curved guide platform: In order to facilitate the smooth advancement of the shield / TBM shield to the heading face, after the excavation of the stepping tunnel is completed, the glass fiber reinforcement mesh is hung, the heading face is sealed with plain sprayed concrete, and a reinforced concrete arc guide platform is constructed. After measurement and layout, the smoothness of the guide platform is controlled according to the axis and horizontal elevation of the stepping tunnel tunnel, the steel bars are tied, the sliding rails are installed, and the rail brackets are welded under the rails with a spacing of 1.5m. The reaction seat positioning steel pipes with a diameter of 150mm are embedded on both sides of the rails with a spacing of 1.5-2m and a pre-embedded depth of 20-30cm. The formwork is erected and the concrete is poured.

3. According to the mechanical combined tunneling construction method for the space-constrained starting shaft interval of claim 1, the shield / TBM ground facilities in step 4 include: Step 4.1: construct gantry crane tracks on the ring beam of the enclosure structure and install two gantry cranes on the tracks; Step 4.2 Install two box-type transformers in the originating well site; Step 4.3: Install a mortar mixing station in the originating well site; Step 4.4: Build a slag pit at one end of the starting shaft, and install a slag screening device next to the slag pit to separate the slag and realize the resource utilization of the slag; Step 4.5: Install a pea gravel hopper on the top of the second tunnel entrance of the TBM. Install an automatic weighing system on the pea gravel hopper. The belt conveys the pea gravel horizontally to the vertical discharge pipe, which is connected to the flatbed truck hopper. Furthermore, in step 5, the expansion section of the shield starting reaction frame installation is: Step 5.1 Before the shield starts, cast the expansion section for the installation of the starting reaction frame of the shield. First, construct the bottom plate of the expansion section. The bottom plate and the arc guide platform of the stepping hole are constructed together. First, tie the bottom plate steel bars of the main structure of the expansion section, embed the positioning steel plates, and pour the bottom plate concrete. Then, set up the full house scaffolding to tie the arch wall steel bars, buckle the combined steel formwork, and pour the arch wall concrete. Pre-embed 4 positioning steel plates on both sides of the bottom plate. The first pair of steel plates are the reaction frame column base connectors, and the steel plate size is 900*600*20mm. The remaining 6 steel plates are the reaction frame diagonal brace connectors, and the steel plate size is 900*600*20mm. The longitudinal spacing of the steel plates is 1m and 1.5m respectively; Step 5.2: 3 positioning steel plates are embedded in the arch position 2m behind the upper crossbeam of the reaction frame, and 1 positioning steel plate is embedded in the arch waist position on both sides of the upper crossbeam end. The size of the steel plate is 500*500*20mm. 4 steel bars are embedded under each steel plate. The length of the steel bar is 500mm, and a 25mm hook is set at the end. Punch plug welding is used between the steel bar and the steel plate; Step 5.3 The expanded section arch wall uses the Mantanghong scaffolding as the formwork support system. A pre-bent arc-shaped arch frame is set up on the top support of the scaffolding, and a composite steel formwork is laid on the arch frame. The longitudinal ribs of the composite steel formwork are retracted inward by 1 to 2 mm to facilitate the outer arc to be smooth during assembly and the formwork joints to be tightly fitted.

4. Mechanical combined tunneling construction method for space-constrained starting shaft interval tunnel, step 6, the first tunnel shield is assembled, and the shield machine forms a normal tunneling state, specifically including the following steps: Step 6.1 After the shield and the screw machine are assembled in the well, they are pushed forward to the starting guide tunnel. When pushing, steel bars are inserted into the steel pipes embedded on both sides of the rails, and steel beams and top irons are installed to provide reaction support for the shield push. Two jacks are fixed on the sliding rails, and a grease drag reduction layer is applied on the rails. The shield is pushed forward to the starting tunnel, and then the reaction frame is lowered into the well and transported to the expansion section for splicing and installation. When the reaction frame is spliced ​​and installed, the center line of the starting mileage section of the reaction frame position is first measured and marked on the side wall of the expansion section to facilitate the center positioning of the reaction frame. The reaction frame is positioned against the positioning plane of the 0 ring segment and is perpendicular to the tunnel axis here. The flatness and verticality allowable deviation is no more than 10mm to ensure the starting accuracy without negative rings. The starting process without negative rings is adopted, and there is no need to remove the negative ring segments. Step 6.2 The bottom of the reaction frame column is welded to the reserved steel plate of the expansion section. The two ends of the upper and bottom beams are supported on the structural side walls and welded firmly to the positioning steel plates on the side walls. The front end of the upper beam is supported on the expanded section arch and the embedded steel plate of the side wall with steel pipe profiles and welded firmly. After the reaction frame is fixed, three diagonal braces on each side of the rear are welded. The diagonal braces are supported by steel pipe profiles. Step 6.3 After the reaction frame is installed, the train marshaling, connecting bridge, No. 1 to 4 trolleys and temporary belt conveyor are lowered into the well. The temporary belt conveyor, connecting bridge, No. 1 to 4 trolleys and the shield are assembled. After the connecting bridge and No. 1 trolley are connected in the starting well, they are pushed into the starting tunnel together and connected to the shield. The other trolleys are connected section by section. The temporary belt slag outlet is set at the position of No. 4 trolley. The main facilities of No. 5 and No. 6 trolleys are spare air compressors, sewage tanks, and high-voltage cable reels. Trolleys No. 6 and 5 are connected in sequence. After going down into the well, it is first stored in the TBM stepping tunnel, and the length of the pipeline between trolleys No. 4 and 5 is extended by 40m. The main pipelines are cables, water pipes and air ducts. The pipeline extension adopts gate-shaped steel brackets and rail-mounted trolleys installed on the side walls of the stepping tunnel. The pipeline is extended as the shield machine steps forward. After the shield machine excavates 40m and meets the length requirements of trolleys No. 5 to 6, the extended pipeline and temporary belt conveyor are removed, and then trolleys No. 5 and 6 are moved forward for assembly of the whole machine to form a normal excavation state until the first shield tunnel is penetrated.

5. According to the mechanical combined tunneling construction method for the space-constrained starting shaft interval of claim 1, the TBM assembly construction in the second tunnel of step 7 is specifically performed as follows: Step 7.1 After the first shield tunnel is penetrated, the portal ring beam of the first shield tunnel is constructed in time, and the TBM equipment of the second tunnel is assembled in the well. The TBM is in double shield excavation mode. When the TBM equipment is long and the step-in tunnel does not meet the requirements of one-time overall start-up, a small split start-up plan is adopted. The start-up is carried out after the assembly of the TBM main engine, connecting bridge, and No. 1 to 5 trolleys is completed. After the excavation meets the conditions for the assembly of the TBM whole machine, the secondary assembly begins; in the case of split start-up, the main engine to the No. 5 trolley are all assembled, and the temporary belt conveyor slag outlet is temporarily modified and placed on the No. 4 trolley. The space behind the No. 5 trolley is used to hoist the pipe segments and temporary slag trucks. At this time, the train formation only has the pipe segment transport truck and the temporary slag truck. The bean gravel hopper is transported by a flatbed truck and shared with the pipe segment truck in the early stage. Due to the limited space behind the No. 5 trolley, the first 4 to 5 rings of excavation slag are not more than 2m 3 The slag bucket is discharged. When the space behind the No. 5 trolley meets the space for the conventional slag bucket hoisting, the conventional 20m 3 The slag bucket is discharged. During the first start, the No. 6 to No. 13 trolleys are temporarily stored in the first shield tunnel, and the pipeline length between the No. 5 and No. 6 trolleys is extended by 110m. After the TBM tunnel has been excavated for 110m and the length of the step-in tunnel has been added, the whole machine can be placed for the second start, the extended pipeline and temporary belt conveyor are removed, and the slag outlet of the subsequent belt conveyor is restored to the No. 8 trolley, and the train formation is restored to normal; Step 7.2 The extended pipeline is erected on the side wall of the shaft using a special pipeline gate steel support. The pipeline support consists of channel steel columns, beams, and rollers. The columns are anchored on the bottom plate of the shaft with a spacing of 1.2 to 1.5 m and a height of 2.5 to 3 m. The remaining pipeline is suspended vertically between two groups of supports. Each group of supports can extend the line for 5 to 6 m, and the rollers are set above the channel steel beams. After entering the stepping tunnel, the pipeline is extended using a hanging rail + trolley. The hanging rail is made of I-beams, which are welded under the corbels. The corbels are fixed to the side wall of the stepping tunnel with a spacing of 0.8 to 1 m. The trolley transport device is installed on the flange of the I-beam. The spacing of the trolley transport device is not more than 500 mm. The pipeline is suspended on the sling of the trolley transport device, which automatically slides forward with the TBM excavation. The first ring of segments is fixed and installed in the form of anchor legs + annular steel plates. Step 7.3 Before the TBM starts, an annular steel plate is set at the end of the starting tunnel. The steel plate is connected to the brackets anchored by multiple anchor rods. The annular steel plate is supported and reinforced with steel sections at the bottom of the tunnel. The end is sealed with cement, and "L"-shaped angle steel and longitudinal arc bolt locking devices and segment sealing devices are installed to ensure that there is no leakage when backfilling and grouting behind the first ring segment.

6. According to the mechanical combined tunneling construction method for the space-constrained starting shaft interval of claim 1, the secondary lining of the stepping hole in step 8: The circular section of the stepping tunnel is lined by the shield / TBM empty-push assembly segment method. Before the start of the shield tunnel, the expanded section of the stepping tunnel is lined for the second time using the Mantanghong scaffolding support formwork system. After the second TBM tunnel is penetrated, the remaining sections of the stepping tunnel are lined for the second time using a full-section hydraulic lining trolley.

7. According to the mechanical combined excavation construction method for the space-constrained starting shaft interval tunnel as described in claim 5, in step 7.3, one end of the "L"-shaped angle steel is in contact with the inner arc surface of the pipe segment, and the other end is welded to the annular steel plate as a whole, and the arc bolts are installed through the longitudinal bolt holes of the pipe segment to connect with the annular steel plate, and the back of the annular steel plate is supported on the wall of the stepping tunnel by steel sections.

8. According to the mechanical combined excavation construction method for a space-constrained starting shaft interval tunnel as described in claim 5, in step 7.3, the segment sealing device is coated with a shield tail grease sealing layer between the segment and the annular steel plate.

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