Highway tunnel vertical shaft guide well expanding excavation method construction method

Abstract

The invention belongs to the technical field of highway tunnel construction, and particularly provides a highway tunnel vertical shaft pilot well expanding excavation construction method which comprises the following steps that a directional drilling machine drills a guide hole from top to bottom; a reamer bit is installed below the guide hole, and reaming is conducted from bottom to top; vertical shaft opening locking construction is conducted; carrying out tunneling and supporting construction on a shaft body; during construction, disintegrating slag falls into a connecting air duct of a main tunnel through the guide hole and is conveyed out through slag discharging equipment; a lifting suspension system, a signal, illumination, a wind and water pipeline and a waterproof and drainage pipeline are installed in the vertical shaft; excavating and supporting the whole section of the vertical shaft to the shaft bottom; assembling a slip form at the bottom of the vertical shaft, and constructing the slip form to a designed elevation; and dismantling the slip form machine, cleaning the site, and completing acceptance. The problems of high construction difficulty, high cost, low construction efficiency, poor safety and the like of deslagging, ventilation and drainage of the traditional normal well excavation method are solved; the slag discharging speed is high, ventilation can be achieved, temporary drainage facilities are omitted, the cost is reduced, and the construction efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of highway tunnel construction, and in particular relates to a highway tunnel vertical shaft pilot shaft expansion construction method. Background Art

[0002] In the process of shaft construction, choosing the right construction method has positive significance for controlling the construction period and cost of the shaft project and reducing the degree of damage to the surface environment. The traditional vertical shaft excavation method faces problems such as great construction difficulty, high cost, low construction efficiency and poor safety in terms of slag discharge, ventilation and drainage. Summary of the invention

[0003] The invention provides a highway tunnel vertical shaft pilot shaft expansion construction method, which aims to overcome the traditional shaft excavation method in the prior art, in which slag discharge, ventilation and drainage all face the problems of great construction difficulty, high cost, low construction efficiency and poor safety.

[0004] To this end, the present invention provides a highway tunnel shaft pilot shaft expansion construction method, comprising the following steps:

[0005] 1) At the center of the shaft to be constructed, a directional drill drills a pilot hole from top to bottom; the tunnel main hole is excavated to the intersection with the bottom of the pilot hole, and support is excavated in the connecting air duct of the tunnel main hole; when drilling the pilot hole, the broken rock cuttings are brought out of the ground by the circulating fluid;

[0006] 2) After the connecting air duct between the pilot hole and the tunnel main hole is connected, remove the directional drilling rig; install the reverse drilling rig, install the reaming drill bit under the pilot hole, and expand the hole from bottom to top;

[0007] 3) dismantling the raise borer and carrying out the shaft locking construction; during the shaft locking construction, firstly excavating the foundation pit and then carrying out the foundation pit slope support;

[0008] 4) Excavation and support construction of the shaft;

[0009] 5) Install lifting suspension system, signal, lighting, wind and water pipelines, and drainage pipelines in the shaft;

[0010] 6) The vertical shaft is excavated and supported to the bottom of the shaft in full section; during the construction of steps 2) to 6), the slag falls through the guide hole to the connecting air duct of the tunnel main tunnel and is transported out through the slag discharge equipment;

[0011] 7) Assemble the slipform at the bottom of the shaft and construct the slipform to the designed elevation;

[0012] 8) Dismantle the slipform machine, clean up the site, and conduct completion acceptance.

[0013] Preferably, a centralizer is used both when drilling the guide hole and when expanding the hole.

[0014] Preferably, the lifting suspension system in step 5) includes a shaft frame, a lifting cage, a safety plate, a wellhead plate and a lifting winch, the shaft head is connected to the wellhead plate, the shaft frame and the lifting winch are respectively installed on one side of the shaft head, the safety plate is installed in the shaft, the lifting cage is placed on the safety plate, the safety plate and the lifting cage are both connected to a set of lifting ropes, and the two sets of lifting ropes are connected to the lifting winch after passing through the wellhead plate and the shaft frame in sequence.

[0015] Preferably, the safety plate comprises a steel frame and an iron plate, the iron plate is horizontally connected to the steel frame, and a rigid guardrail is arranged on the outer periphery of the steel frame.

[0016] Preferably, a movable cover door is provided and connected to the middle part of the steel frame.

[0017] Preferably, the step 6) includes the following steps: first, excavating and blasting a shaft of a certain depth from top to bottom, allowing the blasting slag to slide into the connecting air duct of the main tunnel of the shaft bottom through the guide shaft; after the slag is discharged, installing anchor rods in the shaft, installing arch frames on the anchor rods, installing steel mesh on the arch frames, and finally spraying concrete to complete the full-section excavation and support of a section of the shaft; repeating the above steps to complete the full-section excavation and support of the vertical shaft to the bottom of the shaft.

[0018] Preferably, when the slag does not slide smoothly in the guide hole and blockage occurs, a geological drilling rig dredging process, water storage punching or reverse drilling rig dredging process is used to remove the blockage.

[0019] Preferably, the drainage pipeline includes multiple longitudinal water pipes and multiple transverse water pipes, the multiple longitudinal water pipes are longitudinally distributed at circumferential intervals along the outer side of the support in step 4), and the multiple transverse water pipes are transversely arranged at intervals from top to bottom along the outer side of the support in step 4), and the longitudinal water pipes are perforated corrugated pipes.

[0020] Preferably, waterproof panels are provided and connected to the outer sides of the plurality of longitudinal water pipes and the plurality of transverse water pipes.

[0021] Preferably, the longitudinal water pipe and the transverse water pipe are connected via a four-way connection.

[0022] Beneficial effects of the present invention:

[0023] 1. The construction method of the highway tunnel shaft pilot shaft expansion method provided by the present invention comprises the following steps: 1) at the center of the shaft to be constructed, a directional drilling machine drills a pilot hole from top to bottom; the tunnel main hole is excavated to the intersection with the bottom of the pilot hole, and a connecting air duct of the tunnel main hole is excavated and supported; when drilling the pilot hole, the broken rock debris is brought out of the ground by the circulating fluid; 2) when the pilot hole and the connecting air duct of the tunnel main hole are connected, the directional drilling machine is dismantled; a reverse well drilling machine is installed, and a hole expansion drill bit is installed below the pilot hole to expand the hole from bottom to top; during construction, the broken debris is removed. The slag falls through the guide hole to the connecting air duct of the tunnel main hole and is transported out through the slag discharge equipment; the slag discharge speed is fast. Due to the existence of the guide shaft, the problem of shipping the abandoned slag is well solved, and the excavation speed is greatly improved; the construction risks of the main shaft excavation slag lifting process are avoided, the land acquisition and slag discharge outside the well are reduced, the geological conditions are revealed in advance, the construction risks are reduced, and the safety is guaranteed; the chimney effect of the guide shaft is used to solve the ventilation problem during the excavation process, saving temporary drainage facilities such as water pumps, reducing construction costs, and increasing the excavation speed. By installing the lifting suspension system, signal, lighting, wind and water pipelines, and drainage pipelines in the vertical shaft, the construction drainage efficiency is high, economical and practical, and the operability is good.

[0024] 2. In the highway tunnel vertical shaft pilot shaft expansion construction method provided by the present invention, a centralizer is used when drilling the pilot hole and expanding the hole to prevent deflection during drilling and ensure the hole opening accuracy.

[0025] 3. The highway tunnel shaft pilot shaft expansion construction method provided by the present invention has a lifting suspension system including a shaft frame, a lifting cage, a safety plate, a wellhead plate and a lifting winch, which improves the shaft excavation speed and construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 is a flow chart of the present invention;

[0028] Figure 2 It is a construction diagram of a directional drill drilling into a pilot hole from top to bottom;

[0029] Figure 3 It is a construction schematic diagram of the reaming drill bit reaming from bottom to top;

[0030] Figure 4 It is a distribution diagram of the lifting suspension system;

[0031] Figure 5 It is a schematic diagram of the structure of the safety disk;

[0032] Figure 6 It is a structural schematic diagram of the wellhead plate;

[0033] Figure 7It is the flow chart of drug coil anchor construction;

[0034] Figure 8 Distribution map of drainage pipelines and waterproof panels;

[0035] Fig. 9 yes Figure 8 Longitudinal schematic diagram of middle II;

[0036] Fig.10 It is a schematic diagram of the longitudinal water pipe connecting the transverse water pipe through a cross;

[0037] Fig.11 This is a schematic diagram of double seam welding of waterproof board.

[0038] Explanation of the reference numerals: 1. Safety plate; 1.1. Steel frame; 1.2. Iron plate; 1.3. Movable cover door; 2. Wellhead plate; 2.1. Main beam; 2.2. Support beam; 2.3. Connecting plate; 3. Longitudinal water pipe; 4. Horizontal water pipe; 5. Waterproof board; 6. Cross-joint; 7. Shaft frame; 8. Lifting cage; 9. Lifting winch. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0040] Embodiment 1:

[0041] like Figure 1-Figure 3 As shown, a construction method of a highway tunnel shaft pilot shaft expansion method comprises the following steps:

[0042] 1) At the center of the shaft to be constructed, a directional drill drills a pilot hole from top to bottom; the tunnel main hole is excavated to the intersection with the bottom of the pilot hole, and support is excavated in the connecting air duct of the tunnel main hole; when drilling the pilot hole, the broken rock cuttings are brought out of the ground by the circulating fluid;

[0043] 2) After the connecting air duct between the pilot hole and the tunnel main hole is connected, remove the directional drilling rig; install the reverse drilling rig, install the reaming drill bit under the pilot hole, and expand the hole from bottom to top;

[0044] In actual operation, the diameter of the pilot hole and the diameter of the reaming drill bit used by the directional drilling rig are determined according to needs. For example, a directional drilling rig drills a Φ25cm pilot hole and installs a Φ140cm reaming drill bit below the pilot hole to meet actual needs. The directional drilling rig first uses a three-cone drill bit to drill 2m, removes the cone, connects the active drill rod to the down-the-hole hammer, and then sends it into the hole. The air compressor is started during drilling and starts to supply air when the down-the-hole hammer is 0.3m away from the bottom of the hole. When there is strong wind returning to the wellhead, the drill tool is rotated and slowly sent to the bottom of the hole. When the down-the-hole hammer works normally, drilling is carried out according to the established technical parameters.

[0045] Before the pilot hole construction, the concrete base needs to be poured, the site needs to be leveled and hardened, and then the directional drill rig can be installed. The water consumption for pilot hole drilling and hole expansion cooling should be no less than 15m 3 / H, a water storage tank needs to be set up at the wellhead. The tank size is: 4.0m×2.0m×1.5m. The water source water volume and pumping capacity meet 15m 3 / H of water demand for reverse well construction.

[0046] 3) dismantling the raise borer and carrying out the shaft locking construction; during the shaft locking construction, firstly excavating the foundation pit and then carrying out the foundation pit slope support;

[0047] Specifically, before excavation of the foundation pit, shaft cross-line piles and elevation reference piles are set outside the open excavation slope range according to the given near-well point. The foundation pit excavation is carried out by manual cooperation with the excavator, and the bedrock section is treated by loosening blasting. The foundation bearing capacity is required to be ≥300kpa. The foundation pit slope support can be carried out after acceptance. The foundation pit slope support adopts anchor net spraying support. The designable slope support parameters are: slope slope ratio 1:0.75, height 3m, protection adopts C25 spraying concrete 10cm thick (including Steel mesh 20×20cm)+3m long The spacing between small grouting tubes is 1×1m, arranged in a plum blossom shape.

[0048] 4) Excavation and support construction of the shaft;

[0049] 5) Install lifting suspension system, signal, lighting, wind and water pipelines, and drainage pipelines in the shaft;

[0050] 6) The vertical shaft is excavated and supported to the bottom of the shaft in full section; during the construction of steps 2) to 6), the slag falls through the guide hole to the connecting air duct of the tunnel main tunnel and is transported out through the slag discharge equipment;

[0051] 7) Assemble the slipform at the bottom of the shaft and construct the slipform to the designed elevation;

[0052] 8) Dismantle the slipform machine, clean up the site, and conduct completion acceptance.

[0053] Specifically, this method uses a combination of directional drilling rigs and reverse drilling rigs to construct pilot holes. A directional drilling rig is used to drill the pilot hole. After the pilot hole and the lower connecting air duct are connected, the directional drilling rig is removed, and a reverse drilling rig is installed. A reaming drill bit is installed below the pilot hole to expand the hole from bottom to top. The rock cuttings broken down during the pilot hole drilling are brought out of the ground by the circulating fluid, and the rock cuttings broken down during the hole expansion fall into the connecting air duct by their own weight and are transported out by the slag discharge equipment. The slag discharge speed is fast. Due to the existence of the pilot well, the problem of waste slag transportation has been well solved, and the excavation speed has been greatly improved; the construction risks of the process of lifting the slag during the excavation of the main well and other processes are avoided, and the land acquisition and slag discharge outside the well are reduced. The geological conditions are revealed in advance, the construction risks are reduced, and the safety is guaranteed; the chimney effect of the pilot well is used to solve the ventilation problem during the excavation process, saving temporary drainage facilities such as water pumps, reducing construction costs, and increasing the excavation speed. By installing the lifting suspension system, signal, lighting, Fengshui pipelines, and drainage pipelines in the shaft, the construction drainage efficiency is high, economical and practical, and the operability is good.

[0054] Embodiment 2:

[0055] Based on Example 1, step 1) and step 2) are described in detail:

[0056] Preferably, in step 1), the rotation speed of the directional drill is 25-40 r / min, the drilling pressure is 12-16 kN, and the directional drill maintains full air volume during drilling.

[0057] Specifically, according to the drill bit diameter, the diameter of the carbide column on the drill bit, the impact frequency of the down-the-hole hammer and the diameter of the slag particles, the construction should be controlled at 25-40r / min. To ensure verticality, the construction should be controlled between 12 and 16kN. To ensure smooth slag discharge and clean bottom of the hole, the full air volume should be maintained during construction, that is, 30m3 / min.

[0058] Preferably, a centralizer is used both when drilling the guide hole and when expanding the hole.

[0059] Specifically, the pilot hole is the guide hole of the raise drilling rig, and verticality is a key quality indicator in construction. In order to prevent the drilling hole from deflecting, a centralizer is used. In actual operation, the connection between the drill collar and the impactor can be strengthened. Centralizer, because the drilling tool pressure parameter in the hole is 12~16KN, the drilling tool connection is

[0060] To ensure verticality, the following measures can also be adopted: during construction, adjust the rotation speed in time according to the drilling speed and the size of the returned slag particles; frequently check the horizontality of the derrick during drilling, and correct any problems in a timely manner; reasonably select drilling technical parameters, maintain uniform pressurization, and prevent blindly increasing the pressure, or fluctuating the pressure, to ensure the stability of the drill string; the directional drilling rig is firmly installed, accurately positioned, and the concrete is poured densely.

[0061] Preferably, the directional drill uses deflection measurement when drilling the pilot hole.

[0062] Specifically, a directional drill is used to drill the pilot hole, and the drilling is stopped every 25 meters to measure the deviation to understand the deviation. If the drilling hole deflection angle is greater than 2°, it is considered to be a serious deviation, and the drilling is stopped to correct the deviation. If the deviation is not serious, the deviation correction operation is performed at about 50 meters. After the deviation correction, the drill is continued to be used to drill the pilot hole, and the inclination measurement is performed again every 25 meters to prevent abnormal deviation.

[0063] Preferably, when the directional drill encounters a weak interlayer section, a weathered rock section with a gravel structure, a section with developed fissures, a local collapse hole and a crushing when drilling the pilot hole, the following measures are adopted:

[0064] When encountering a weak interlayer section, high-pressure air is used to continuously flush the hole to flush the mud structure of the weak interlayer section out of the hole mouth, and then mortar backfill is carried out. After the mortar reaches the target strength, a second drilling is carried out to pass through the weak interlayer section.

[0065] Specifically, the weak interlayer section is a mud structure. When drilling to this section, the drilling progress and slag return are analyzed and judged. During drilling, high-pressure air (3.45Mpa) is used to continuously wash the hole to flush the mud structure out of the hole, and then mortar is backfilled. After the mortar reaches a certain strength, the second drilling is carried out through this section.

[0066] When encountering weathered rock sections with gravel structure, adopt segmented mortar replacement and secondary drilling after the strength reaches the target strength.

[0067] Specifically, the weathered rock section with gravel structure has the physical properties of "quicksand layer". When encountering this section, it is difficult to advance, resulting in drill bit jamming. At the same time, gravel is continuously flushed out of the hole to form a cavity. The mortar is replaced in sections. When the strength reaches 15Mpa, drilling is carried out for the second time. After circulating through this section and entering the normal surrounding rock, deep hole positioning and high-pressure sealing grouting are carried out.

[0068] When encountering a section with developed fractures, grouting is carried out through the center hole of the drill pipe to fill the fractures.

[0069] Specifically, in the section where fractures develop, air leakage occurs and slag cannot be returned, so grouting is carried out through the center hole of the drill pipe. Under deep pressure, the slurry consolidates the rock mass around the hole and fills the fractures.

[0070] When encountering partial hole collapse and breakage but still passable, high-pressure grouting is carried out to seal the entire guide hole 20m before the guide hole is passed, and the hole wall and the surrounding area are consolidated.

[0071] The construction of the pilot hole is an accurate exploration of the geological conditions of the wellbore. Geological defects need to be resolved during the pilot hole construction to avoid the occurrence of hole collapse during the reverse well construction.

[0072] Embodiment 3:

[0073] Based on Example 2, step 5) lifting the suspension system is described in detail:

[0074] Preferably, Figure 4 As shown, the lifting suspension system in step 5) includes a shaft frame 7, a lifting cage 8, a safety plate 1, a wellhead plate 2 and a lifting winch 9. The shaft head is connected to the wellhead plate 2. The shaft frame 7 and the lifting winch 9 are respectively installed on one side of the shaft head. The safety plate 1 is installed in the shaft of the shaft. The lifting cage 8 is placed on the safety plate 1. The safety plate 1 and the lifting cage 8 are both connected to a set of lifting ropes. The two sets of lifting ropes are successively passed through the wellhead plate 2 and the shaft frame 7 and then connected to the lifting winch 9.

[0075] Specifically, during the shaft construction process, the lifting and suspension system is the key to restricting the shaft excavation speed and construction safety. The shaft construction space is narrow and the construction safety risk is high. The lifting and suspension system of the present invention has high construction efficiency and good safety.

[0076] Preferably, the vertical shaft derrick is an on-site processed derrick.

[0077] Specifically, the vertical shaft derrick is a pavilion-type derrick specially used for the vertical shaft "reverse shaft method" construction, which is composed of a sheave, a sheave platform, a frame, a ladder and a foundation. The "reverse shaft method" derrick system is mainly used for the up and down of vertical shaft construction personnel and vertical shaft construction materials and machinery. The traditional "reverse shaft method" construction uses an assembled derrick, and this method uses on-site processing of the derrick, which greatly reduces the production and installation costs of the traditional "reverse shaft method" construction derrick.

[0078] The vertical main frame of the derrick adopts Steel pipe, connecting the auxiliary frame The steel pipe and derrick are processed and assembled on site, and the derrick is installed manually with the help of crane. The derrick foundation is 1m long, 1m wide and 1m high, and is cast in place with concrete. The steel pipe is cast into a whole. The derrick is equipped with lightning protection devices as required.

[0079] The cage is used for lifting personnel, equipment and materials up and down in the shaft.

[0080] Preferably, Figure 5As shown, the safety plate comprises a steel frame 1.1 and an iron plate 1.2, the iron plate 1.2 is horizontally connected to the steel frame 1.1, and a rigid guardrail is arranged on the outer periphery of the steel frame 1.1.

[0081] Specifically, the safety plate is a protective plate for the construction of the working face, and also serves as the foundation of the cage stabilization device. It is made on-site using section steels 25, 18, and 16, and the safety plate is paved with ξ3mm patterned iron plates. Two JZ-10t well-drilling stabilization vehicles suspend the safety plate through two main steel wire ropes, and the main steel wire ropes are connected to the safety plate through four "eight" ropes. The safety plate has four hanging points, and two hanging points on one side are suspended by a stabilization vehicle. The hanging point design is based on the stability of the hanging plate and the convenience of construction. A fixed pulley is set on each side of the wellhead plate as a guide pulley for the stabilization vehicle wire rope. A 1.2m high-rigidity guardrail is set around the safety plate to ensure the safety of people during the lifting process.

[0082] Preferably, a movable cover door 1.3 is provided and connected to the middle portion of the steel frame 1.1.

[0083] Specifically, an opening is provided in the middle of the safety disk with a size of 2.6m×2.6m. The opening is a reserved center hole for centerline measurement, which is used for the passage of the plumb ball before drilling, and a movable cover door is provided for easy opening or closing.

[0084] Preferably, Figure 6 As shown, the wellhead plate includes a main beam 2.1, a support beam 2.2 and a connecting plate 2.3. The main beam is in a well shape. The inner and outer sides of the main beam are connected to the support beams. The connecting plates are laid flat between the main beam and the support beams. The middle part of the main beam is open and no connecting plate is laid.

[0085] Specifically, a wellhead plate is set at the shaft mouth, with a diameter of 7.2m (the inner diameter of the shaft lock is 6.4m). The main beam of the wellhead plate is made of I32a×2 type industrial steel, with 2 pull-throughs in the horizontal and vertical directions; the support beam is made of I25a I-beam, I20a I-beam and 14 channel steel; the connection plate is covered with 3mm iron sheet, which is welded to the I-beam. The structure is simple, economical and practical.

[0086] Embodiment 4:

[0087] Based on Example 3, step 4) is described in detail:

[0088] Preferably, the support construction in step 4) is carried out on a safety plate, and during the construction, the movable cover door 1.3 of the safety plate is closed to prevent personnel from slipping.

[0089] Specifically, Figure 7 As shown in the figure, the support construction includes the following steps:

[0090] 1) Initial spraying: After the slag is discharged, the surrounding rock is sprayed initially, and the spraying thickness of C25 concrete is 2 to 4 cm;

[0091] 2) System anchor construction: Vertical shaft anchor adopts drug roll anchor. The construction steps of drug roll anchor are as follows: after construction preparation and construction layout measurement, arrange the anchor hole position, carry out anchor drilling, clean the hole after drilling, and inspect the hole after cleaning; if the inspection fails, make up the hole and clean the hole again until the hole after cleaning passes the inspection; configure drug roll, fill the drug roll in the hole after inspection, make and transport the anchor and its accessories, install the anchor in the anchor hole position, add the pad, tighten the nut, and fix the rod body until the installation passes, and process and inspect the hole mouth after installation. If the inspection fails, rearrange the anchor hole position and repeat the above steps until the inspection passes, and enter the next process after inspection. It is required that when the rod body is inserted into the anchor hole, the position should be kept in the middle, and the length of the anchor rod body exposed from the rock surface should not be greater than the thickness of the spray layer. The allowable error of the anchor hole spacing is ±100mm.

[0092] 3) Install the grid steel frame, specifically: before installing the arch frame, spray 4cm thick C25 shotcrete to ensure that the outer edge of the main reinforcement has sufficient concrete protective layer thickness. The gap between the steel frame and the surrounding rock should be tightened in time with wedge blocks to ensure the thickness of the structure. One end of the positioning bar is spot welded to the steel frame, and the other end is drilled in the surrounding rock at the steel frame erection location. The anchor rods are used for positioning, and the steel frames are connected with M20*60 bolts. In order to facilitate the transportation and lifting of the steel frame, the steel frame used in the shaft construction is processed according to 8 sections / frame. The secondary lining of the shaft is applied after the excavation of the entire shaft and the completion of the initial support construction. In order to make the initial support close to the surrounding rock and form an effective support structure, the initial support grid steel arch frame and radial anchor rods and steel mesh need to be welded together. The steel grid is 80cm per frame, and the steel frame connecting bar adopts Φ22 thread and is arranged every 1m. The connecting bars are made of Φ22 threaded steel, with a spacing of 80cm for Grade IV surrounding rock. The connecting bars and steel sections are double-sided welded, and the weld thickness is not less than 4mm.

[0093] 4) Steel mesh construction: The steel mesh in the shaft section is Ф8 mesh, with a grid spacing of 20*20cm, a processing specification of 1.2*1.5m, and the overlap of each mesh joint is not less than 20cm. The mesh is tightly attached to the well wall and connected to the anchor rod, and the anchor rod pad is tightly attached to the mesh.

[0094] 5) Shotcrete: The shotcrete material is mixed by the vertical shaft shotcrete mixing station. The storage time of the shotcrete mixture shall not exceed 30 minutes. 3 Air compressors supply air. For rock surfaces with gushing, seepage or moisture, different treatments should be carried out before spraying: large gushing water should be blocked by grouting before spraying concrete; small water or crack seepage water should be grouted on the rock surface or drained by ducts before spraying concrete; large areas of moisture on rock surfaces should use concrete with strong adhesion, such as adding admixtures and additives to improve the performance of concrete; when there are large concave areas on the rock surface, the concave areas should be sprayed flat first.

[0095] The thickness of the initial sprayed concrete shall not be less than 4cm. The spraying operation shall be carried out in sections, pieces, layers, from bottom to top, and the length of each section shall not be greater than 6m. When spraying in layers, the next layer shall be sprayed after the previous layer of concrete has finally set. The nozzle shall be moved horizontally and circularly continuously and slowly, and the thickness of the sprayed layer shall be uniform.

[0096] Embodiment 5:

[0097] Based on Example 4, the Feng Shui pipeline in step 5) is described in detail:

[0098] Specifically, the shaft air duct uses medium I14 welded pipe, the water pipe uses medium 48 welded pipe, the wind and water pipe uses a stable car suspension, the sealing plate sets a pulley, the stable car wire rope guides the suspended wind and water pipe through the fixed pulley, the wind and water pipe and the wire rope are connected by a U-shaped buckle, and the bottom is fixed on the safety plate. The wind and water pipe connection uses a flange plate. The high-pressure wind and water pipe is laid to about 25m from the bottom of the well, and the end is equipped with a gate valve reducer connected to the hose, and the wind and water are led to the face through the hose and the nine taps. During blasting operations, the wind and water hoses are rolled up and placed on the safety plate to prevent blasting damage.

[0099] Detailed description of the drainage pipeline in step 5):

[0100] Preferably, Figure 8-Figure 10 As shown, the drainage pipeline includes multiple longitudinal water pipes 3 and multiple transverse water pipes 4. The multiple longitudinal water pipes 3 are longitudinally distributed at circumferential intervals along the outer side of the step 4) support, and the multiple transverse water pipes 4 are transversely arranged at intervals from top to bottom along the outer side of the step 4) support. The longitudinal water pipes 3 are perforated corrugated pipes.

[0101] Specifically, tunnel waterproofing is mainly based on structural self-waterproofing, with construction joints, deformation joints and other joint waterproofing as the focus, taking measures to control the anti-seepage performance of concrete, and supplemented by grouting and waterproof layer reinforcement. The horizontal water pipe 4 is an annular drainage pipe, which is set at a longitudinal interval of every 10 meters from the lock plate to the bottom of the well. The longitudinal water pipe 3 is symmetrically set with four perforated corrugated pipes from the lock plate to the bottom of the well to introduce groundwater into the annular ditch at the bottom of the well. It has a simple structure, convenient construction and good drainage effect.

[0102] Preferably, waterproof plates 5 are connected to the outer sides of the plurality of longitudinal water pipes 3 and the plurality of transverse water pipes 4 .

[0103] Specifically, an EVA composite waterproof board 5 with a thickness of not less than 1.5 mm is arranged behind the shaft lining, and a non-woven fabric buffer layer is arranged behind the waterproof board 5, which has a simple structure, is economical and practical, and has a good waterproof effect.

[0104] Preferably, Fig.11As shown, the waterproof board 5 adopts hot-melt welding technology, and the weld width is not less than 10 cm; the laying length of the waterproof board 5 is determined according to the length of the concrete cycle pouring, and is 2 to 3 cycles ahead of the lining construction; the joint welding of the waterproof board 5 adopts double-seam welding with a creeping heat sealing machine.

[0105] Specifically: overlap the edges of two waterproof sheets 5 and effectively bond them by hot melting and pressurizing. The overlapping width of the waterproof sheets 5 is not less than 150mm on the short side, not less than 150mm on the long side, and the weld width is not less than 10mm. After the heat sealer is preheated, place it between the two waterproof sheets 5, move it to melt the waterproof sheets 5, and pressurize it until the joint is firmly bonded.

[0106] Preferably, when the waterproof board 5 is welded, when the vertical weld and the horizontal weld intersect in a cross (cross weld), before welding the second weld, the extra edge outside the first weld is cut off, the step is repaired into an inclined surface and melted flat, and the trimming length is greater than 12mm, so as to ensure the welding quality and the smooth passage of the welding machine.

[0107] Preferably, during waterproofing construction, the horizontal construction joint is provided with an expansion water stop strip waterproof structure; the deformation joint waterproofing adopts a composite waterproof structure composed of a back-sticking water stop strip, a middle-embedded rubber water stop strip and caulking materials to improve the waterproofing effect.

[0108] Preferably, Fig.10 As shown, the longitudinal water pipe 3 and the transverse water pipe 4 are connected via a cross 6. The connection is simple and the construction is easy.

[0109] Embodiment 6:

[0110] On the basis of Example 5, the step 6) includes the following steps: first, a shaft of a certain depth is excavated and blasted from top to bottom, and the blasting slag slides into the connecting air duct of the main tunnel of the shaft bottom through the guide shaft. After the slag is discharged, anchor rods are installed in the shaft, arch frames are installed on the anchor rods, and steel mesh is installed on the arch frames. Finally, concrete is sprayed to complete the full-section excavation and support of a section of the shaft; the above steps are repeated to complete the full-section excavation and support of the vertical shaft to the bottom of the shaft.

[0111] Preferably, when the slag does not slide smoothly in the guide hole and blockage occurs, a geological drilling rig dredging process, water storage punching or reverse drilling rig dredging process is used to remove the blockage.

[0112] Specifically, during the forward excavation construction stage, the slag well is occasionally blocked due to factors such as small diameter of the slag well, unsatisfactory blasting effect, and untimely slag discharge from the bottom, thus affecting construction safety and progress. At present, the main methods for treating the blocked holes are: geological drilling rig unblocking treatment, water storage punching, and reverse drilling rig unblocking treatment.

[0113] The blasting holes should be constructed according to the hole spacing, depth and charge amount determined by the design, and the over-excavation and under-excavation should be strictly controlled to ensure that the maximum diameter of the rock slag does not exceed 50cm (1 / 3 of the diameter of the slag chute) to prevent hole blockage during the slag chute process.

[0114] If the slag well is blocked accidentally during construction, micro-blasting or mechanically assisted manual clearing (geological drilling rig clearing, water storage punching or reverse drilling rig clearing) should be adopted after the cause is found out. If the upper part of the slag well is blocked after blasting, the slag is lifted upwards, and the slag is discharged to the bottom of the well after passing through the blocked section; if the middle and lower parts are blocked, weak blasting or traction clearing is adopted to solve the blockage problem and make the slag body slide out from the slag channel.

[0115] Embodiment 7:

[0116] Based on Example 6, the slipform construction is described in detail:

[0117] After the excavation and initial support construction is completed, the secondary lining of the shaft wall is constructed. According to the design requirements, the shaft of the ventilation shaft is a cylindrical structure, and the lower part (connected to the horse head gate) is a well D-5400mm. Slipform casting is used for the secondary lining construction. Before slipform casting, the shaft is first constructed with drainage pipes and waterproof boards 5 in accordance with the specifications and design requirements. The drainage facilities are cast 5m in advance. Before casting the bottom plate of the shaft, the drainage pipe facilities are connected to the drainage ditch of the communication channel.

[0118] The characteristics of slipform construction are fast construction speed and less joints. Rebar binding, concrete pouring and slipform lifting are carried out in parallel, and each process is carried out continuously and adapts to each other.

[0119] Slipform construction is carried out using a slipform operating panel, auxiliary panel, lifting frame, hydraulic system, support rods, auxiliary systems, etc.

[0120] Preferably, the slipform operating panel adopts light truss beams arranged radially.

[0121] Specifically, the sliding form operating panel is the main load-bearing component of the sliding form and also the operating platform during construction. In the design of the sliding form operating panel, its weight should be reduced as much as possible while ensuring its strength, rigidity and stability. Therefore, light truss beams are used and radially arranged.

[0122] Preferably, the light truss beam includes two layers of upper and lower enclosures, and the enclosures are made of 8-channel steel.

[0123] In order to ensure the stability of the truss beam, two layers of enclosures are set up, and the enclosures are made of 8-channel steel. The slip formwork is formed by processing §4mm steel plates, and the inner side of the steel plate and the enclosure are connected with ∠63*6 angle steel bolts. The plate surface is paved densely with horseway boards.

[0124] Preferably, the auxiliary plate adopts a wide hanging steel ring, a wooden step plate is laid on the steel ring, and a safety net is hung inside and outside the steel ring.

[0125] Specifically, the auxiliary panel is located 2.0m below the operating panel. It is mainly used for plastering, checking the quality of concrete walls, dealing with local defects, sprinkling water for maintenance, etc. In order to reduce its weight, a 1.0m wide hanging φ25 steel bar ring is used, wooden treads are laid, safety nets are hung inside and outside, and 18mm diameter round steel is used to suspend it at the bottom of the radiation truss.

[0126] Preferably, the lifting frame is made of channel steel into an "F"-shaped lifting frame; the hydraulic system includes a hydraulic jack, a hydraulic control console and an oil pipe, and the hydraulic control console is a ZYXT-36 automatic leveling hydraulic control console; and the support rod is made of welded steel pipe.

[0127] Specifically, the lifting frame is made of 16 channel steel into an "F" type lifting frame. A total of 8 HM-100 hydraulic jacks are selected, with a designed load capacity of 120KN, a stroke of 30mm, and a calculated load capacity of 74KN. The hydraulic control console is a ZYXT-36 automatic leveling hydraulic control console. High-pressure oil pipe: the main pipe is φ16mm; the branch pipe is φ8mm, and the straight pipe joint and six-way joint are used to connect the control console and jack in groups to form a hydraulic system. The support rod is φ50×4 welded steel pipe.

[0128] When in use, first insert the 48mm support rod from top to bottom into the center hole of the jack, then start the oil pump, the oil enters the oil cylinder from the jack's oil inlet nozzle, and presses the piston down between the cylinder barrel, cylinder head and piston, but the piston cannot drop because the upper clamp is locked with the support rod: press the cylinder head upward, then the lower clamp is opened, and the entire cylinder body is lifted under the action of oil pressure. When it rises to the point where the upper and lower clamps are pressed against each other, the lifting process is completed. At this time, the oil discharge spring is in a compressed state. When the oil is returned, the oil pressure is released, and the oil discharge spring rebounds. Under its pressure, the lower clamp is locked with the support rod, lifting the upper clamp and the piston upward, and the oil is discharged from the oil nozzle to the cylinder, completing the reset process. The lifting process and the reset process constitute a climbing cycle of the hydraulic jack. The stroke of one cycle is generally 20 to 30 mm. Pressurization means lifting, and oil discharge means reset, and the jack continues to climb along the support rod in such a reciprocating cycle. The allowable load of the jack generally does not exceed one-half of its rated value.

[0129] The auxiliary system includes devices such as watering maintenance, center measurement, and level control measurement.

[0130] Specifically, watering maintenance is an important part of concrete construction, and the shaft stabilization suspension The water pipe is connected to the working plate, and the safety valve controls and releases the pressure. The PVC pipe is divided into two branches underground, which are arranged along the concrete surface in the well. Holes are drilled on the PVC pipe and the concrete surface is sprinkled with water for maintenance.

[0131] For center measurement, on a wellhead that has been firmly fixed, the center line of the wellbore is determined using a total station, and then the center line control of the measurement is performed using a laser pointer that is separately fixed on the well wall below the wellhead.

[0132] The level measurement utilizes the principle of the level tube. A transparent rubber tube is arranged on the model, filled with water and fixed on the model for level observation.

[0133] Preferably, the slipform construction comprises the following steps:

[0134] 1) Tie up steel bars and extend climbing poles

[0135] Specifically: After the slipform body is assembled and debugged, the steel bars are tied and welded according to the construction drawings. During the sliding construction, the top layer of horizontal bars is exposed after the concrete is poured. The spacing of the steel bars meets the requirements. Each layer of horizontal steel bars is in a horizontal plane. The joints between the upper and lower layers are staggered. The spacing of the vertical bars is evenly arranged according to the design. The joints of adjacent steel bars should be staggered. At the same time, the lifting frame is used to weld steel pipes to control the steel bar protection layer. The number of joints of the climbing poles at the same level does not exceed 1 / 4. Therefore, the first set of climbing poles has more than 4 length specifications (2.5m3.5m4.5m6.0m...), staggered arrangement. During normal sliding, each climbing pole is 6.0m long. The climbing pole specifications are The surface is flat and free of rust. When the jack is less than 350mm from the top of the climbing pole, extend the climbing pole, grind one end of the joint into a ridge with an angle grinder, connect the lower part, align the joints, and weld them firmly. After welding, grind it flat with an angle grinder to ensure that the jack passes through the climbing pole smoothly. The climbing pole is connected to the ring reinforcement and welded for reinforcement.

[0136] 2) Concrete transportation and storage

[0137] Specifically: concrete for slipform construction is centrally provided by the mixing station, slides to the collecting hopper above the wellhead through a chute (belt transmission), and then directly unloaded through a discharge chute. The discharge chute is equipped with a buffer device to overcome the acceleration of concrete under the action of gravity and the separation of aggregates.

[0138] 3) Transportation of steel bars and personnel

[0139] Specifically, when the shaft is being poured at the bottom, the steel bars can be directly hoisted from the bottom of the shaft to the working surface. As the pouring position rises, the materials and construction personnel in the shaft are hoisted by the hoisting winch and transported to the safety plate, and then moved from the safety plate to the slipform operation platform. A safety ladder is set between the safety plate and the slipform operation plate.

[0140] 4) Concrete pouring

[0141] Specifically, concrete is mixed at the mixing station according to the required proportions, and transported to the wellhead by concrete tank trucks. Slipform construction is carried out in the following order: unloading → flattening and vibrating → sliding → steel bar binding → unloading. During slipform construction, concrete is unloaded symmetrically and evenly. The slump of slipform concrete is required to be controlled at 9 to 11 cm, and the height of concrete put into the mold each time shall not exceed 300 mm. The vibrator is inserted for tamping. When vibrating, the vibrating rod should be inserted into the lower layer for 10cm, and the insertion spacing is 1.5 times the insertion depth. When vibrating, follow the method of "fast insertion and slow withdrawal". The vibration time is 30 to 50 seconds, generally until the surface layer returns to slurry and there are no bubbles, without missing vibrations or over-vibration. And avoid vibrating the climbing pole and formwork directly, and stop vibrating when the formwork slides. The normal sliding of the slipform determines the reasonable sliding speed according to the specific conditions of the initial setting of concrete, concrete feeding, construction coordination, etc. at the construction site, and the interval time of layered pouring shall not exceed the allowable interval time. During normal sliding, each interval is 1 hour, and the sliding height is controlled to 30cm, and the daily sliding height is controlled to about 5m.

[0142] The initial sliding of the slipform formwork should be carried out slowly, and during this process, the lifting system, hydraulic control system, disk surface and deformation of the formwork should be fully checked. If any problems are found, they should be dealt with in a timely manner. Normal pouring and sliding can be carried out only after everything is normal.

[0143] During the pouring process, test blocks should be retained according to the specifications and stored in a place with the same curing conditions as the well wall for curing. After reaching 28 days of age, strength test should be carried out.

[0144] If water outlets are found in the rock wall during the wall construction process, holes should be drilled with a rock drill to collect water and water pipes should be buried. The water pipes can be made of rubber hoses in the concrete section, but steel pipes with flanges should be used for the part exposed outside the well wall to prepare for grouting and water sealing in the later stage. When dealing with water outlets in the rock wall, water should not enter the formwork to affect the quality of the concrete.

[0145] 5) Sliding formwork

[0146] Specifically: When the construction enters normal pouring and sliding, maintain continuous construction, observe and analyze the concrete surface conditions, and determine the reasonable sliding speed and layered pouring thickness according to the site conditions. During the sliding process, check the condition of the jack, observe whether the indentation and stress state on the climbing rod are normal, and check the horizontality of the sliding form center line and the operating panel.

[0147] 6) Surface finishing and maintenance

[0148] Specifically: surface finishing is a process related to the quality of the structure's appearance and protective layer. This work must be carried out immediately after the concrete is demoulded. Generally, a trowel is used to flatten or repair the concrete surface. If the surface is flat, no finishing is required. In order to ensure that the poured concrete has suitable hardening conditions and reduce cracks, a sprinkler pipe is installed on the auxiliary plate to maintain the concrete.

[0149] 7) Stop-slip measures and construction joint treatment

[0150] Specifically: Slipform construction should be carried out continuously, and "stop-slip measures" should be taken in case of unexpected stoppage. After concrete pouring stops, the slide should be lifted 1 to 2 times every 0.5 to 1 hour until the concrete and the formwork are no longer bonded (usually about 4 hours). If the slipform stops due to other reasons, the construction joints should be treated in advance on the concrete surface in accordance with relevant construction specifications, and then the residue on the concrete surface should be removed before resuming work, and it should be rinsed with water. A layer of half-reduced aggregate concrete or cement mortar should be poured first, and then the original concrete should be poured.

[0151] 8) Sliding mode centerline control

[0152] Specifically: To ensure that the center of the structure does not deviate, the center point is determined by using a ground total station, and a 60kg hammer ball is suspended by a steel wire rope for center auxiliary control; at the same time, two laser pointers are fixed on the well wall below the wellhead platform beam to control the sliding mode position. Fixed observation points at the wellhead are frequently reviewed.

[0153] 9) Sliding mode level control

[0154] Specifically: use the synchronizer of the jack to control the level; use the level to measure and check the level.

[0155] 10) Slipform removal

[0156] Specifically: when the slipform slides up close to the wellhead, remove the wellhead platform and continue construction. When the concrete is poured to the designed elevation, slide the formwork into the air and use a crane to suspend and remove the formwork as a whole. The following matters should be noted when removing the slipform formwork:

[0157] A. The disassembled sliding form parts should be strictly inspected and lowered after being firmly tied;

[0158] B. During the construction of the secondary lining of the well body, a certain amount of grouting pipes should be reserved in the broken zone or where water is developed in the joints and fissures to ensure that any voids behind the secondary lining can be dealt with in a timely manner.

[0159] C. The concrete feed pipe adopts Φ219*4mm welded pipe. The upper pipe opening of the feed pipe is 80cm below the bottom. The steel wire rope is symmetrically welded to fix the lifting ring. Two JZ-10 stabilizers are used to suspend the feed pipe through two D24.5 steel wire ropes. The steel wire ropes and the feed pipes are fixed by rope clamps. According to the vertical depth of Baimashan No. 1 Tunnel, 120 / 6=20 pipes, 19 pipes are actually laid. The bottom feed pipe is connected to the buffer. The lower part of the buffer is suspended with a string tube. The single section of the string tube is 1m and can swing freely. The lifting is based on the rising distance of the warehouse surface, and the string tube is removed to ensure that the concrete enters the warehouse. According to the characteristics of "cohesiveness" of concrete soil, the feed pipe is buffered every 6m to ensure that the gravity acceleration of the concrete during the fall is only accelerated at a height of 6m. After passing through the two feed pipes, a uniform speed state is formed. At the same time, the concrete is mixed twice in the pipe to avoid the separation of the concrete and aggregate entering the warehouse.

[0160] Preferably, during the slipform construction, when the slipform operating plate tilts, the slipform plate translates and twists, the jack itself is used to correct the deviation; when the formwork is deformed, it is restored by pressurizing with support rods or the formwork is removed for repair; when concrete surface defects occur, local formwork is used, and expanded fine aggregate concrete with a higher grade than the original is added and smoothed; when there is a problem of bending of the climbing pole, steel bars or oblique supports are welded, and when the bending is severe, the bent climbing pole is cut off, and the straight climbing pole is connected and re-welded to the lower climbing pole, and a "human" shaped oblique support is welded.

[0161] Specifically, use the jacks to correct the deviation by themselves, that is, close one-fifth of the jacks, then slide up 2-3 strokes, then open all the jacks and slide up 2-3 strokes, repeat several times and gradually adjust to the design requirements. And according to various different situations, apply a certain external force to correct the deviation. All correction work should not be done too hastily to avoid accidents such as cracking of the concrete surface, dead bends, deformation of the sliding formwork, bending of the climbing pole, etc.

[0162] The highway tunnel shaft pilot shaft expansion construction method of the present invention has the following benefits:

[0163] 1. Social benefits

[0164] During the implementation of this construction method, appropriate measures were taken and no safety or quality accidents occurred. The construction progress was accelerated, the construction period was guaranteed, the construction energy consumption was reduced, and the social benefits were significant.

[0165] 2. Safety benefits

[0166] Compared with traditional construction methods, this method avoids the construction risks in the process of lifting the slag during the excavation of the main well, reveals the geological conditions in advance, reduces the construction risks, and ensures safety. During the construction process, the construction water or the water in the well flows naturally from the pilot well to the main tunnel at the bottom of the well and is discharged, which saves temporary drainage facilities such as water pumps, fundamentally avoids the problem of well flooding, reduces construction costs, and increases the speed of excavation.

[0167] 3. Environmental benefits

[0168] No need to arrange waste dump and sewage treatment station at the wellhead: it reduces land acquisition and slag discharge outside the well, and reduces damage to the environment. No need for temporary ventilation and drainage facilities: the chimney effect of the pilot well is used to solve the ventilation problem during the excavation process, greatly improving the air quality of the shaft and the main hole.

[0169] 4. Economic benefits

[0170] After the excavation and support construction of the ventilation shaft of Baimashan No. 1 Tunnel was completed in July 2023, after cost analysis and comparison, the use of the "pilot shaft expansion method" for excavation construction can effectively speed up the construction progress, greatly save construction costs, and reduce construction safety risks. Compared with the traditional shaft construction method, the slag after blasting falls into the connecting air duct at the bottom of the tunnel through the pilot shaft, and then is loaded and transported by a loader. Due to the existence of the pilot shaft, the problem of shipping the waste slag has been well solved, and the excavation speed has been greatly improved.

[0171] The excavation construction of the "pilot shaft expansion method" takes a total of 50 days, the equipment installation and commissioning time on site takes 10 days, there are about 30 people during the shaft excavation period, 10 people during the equipment installation period, and the total construction period is 60 days. The construction process of the straight shaft method requires 60 days of excavation construction, 45 days of equipment installation and commissioning time on site, 30 people during the equipment installation period, 50 people during the shaft excavation period, and a total construction period of 105 days. The straight shaft method requires the disposal of slag above the wellhead. At the same time, the straight shaft method requires a large investment in equipment, and the equipment installation and commissioning consumes a lot of manpower and material resources, and occupies a large area. According to calculations, the use of the "pilot shaft expansion method" for this vertical shaft can create a benefit of 4.7083 million yuan compared to the "straight shaft method". The calculation process is as follows:

[0172] Table 1 Economic Benefit Calculation Table

[0173]

[0174] Table 2 Construction cost calculation table

[0175]

[0176] Note: During the actual construction of the ventilation shaft of Baimashan Tunnel No. 1, the pressurized water output was small, and the drainage efficiency of the pilot shaft was not reflected. If the cost of drilling and grouting by the pump was calculated, the economic benefits created would be greater. At the same time, compared with the straight shaft method, this method has minimal environmental pollution and reduces environmental maintenance costs.

[0177] Application Examples

[0178] 1. Ventilation shaft of Baimashan No. 1 tunnel in Bapeng Road Section 9 of Chongqing-Hunan double-track line

[0179] Baimashan No. 1 Tunnel of Chongqing-Hunan Double Line Expressway (Banan to Pengshui Section) is located in Changba Town and Baima Town, Wulong District, Chongqing. Baimashan No. 1 Tunnel (ZK102+335~ZK108+112 / K102+344~K108+088) has a left tunnel length of 5777m and a right tunnel length of 5744m. The tunnel operation ventilation adopts shaft ventilation, and there is a ventilation shaft for the left and right lines. The shaft intersects 50m to the left of ZK104+354.12m of the tunnel body. The shaft is 118.537m deep; the clear section of the shaft is circular, with a diameter of 5.4m and a clear area of ​​22.9㎡. The tunnel ventilation adopts a combined setting of left and right tunnels, and smoke and dust are removed from the tunnel through a connecting air duct.

[0180] The excavation time of the ventilation shaft of Baimashan No. 1 Tunnel using this method is from May 22, 2023 to July 11, 2023. During the implementation process, the measures were appropriate, no safety and quality accidents occurred, the construction progress was accelerated, the construction period was guaranteed, the construction energy consumption was reduced, and the social benefits were significant.

[0181] 2. Pengshui Tunnel Ventilation Shaft, Section 14, Bapeng Road, Chongqing-Hunan Double Line

[0182] The Bapeng Road 14th Project undertaken by China Railway 12th Bureau Group Co., Ltd., the control project of this project, Pengshui Tunnel, is designed as a double-hole one-way super-long tunnel. The tunnel form is small and clean + separation type, with a total length of 11135m for the left tunnel and 11094m for the right tunnel. Two ventilation shafts are set up, with an inner diameter of 8.2m and a depth of 202.2m for the A shaft, and an inner diameter of 7.0m and a depth of 194.4m for the B shaft. The excavation time using this method is from May 17, 2023 to July 25, 2023. This method is used in the construction of the ventilation shaft of the tunnel. This method has low cost, fast speed, good and safe working environment, small ground area, little damage to the natural environment, small scale or no repair of the access road, and the bottom flat hole has been completed, which has convenient conditions for slag discharge and high slag discharge efficiency. The "highway tunnel shaft "pilot shaft expansion method" construction method" has obvious application effect in the ventilation shaft of Pengshui Tunnel.

[0183] In the description of the present invention, it should be understood that if there are terms indicating an orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention.

[0184] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A construction method for highway tunnel vertical shaft pilot shaft expansion method, Features: The steps include: 1) At the center of the shaft to be constructed, a directional drill drills a pilot hole from top to bottom; the tunnel main hole is excavated to the intersection with the bottom of the pilot hole, and support is excavated in the connecting air duct of the tunnel main hole; when drilling the pilot hole, the broken rock cuttings are brought out of the ground by the circulating fluid; 2) When the connecting air duct between the pilot hole and the tunnel main hole is connected, the directional drilling rig is dismantled; Install a raise borer, install a reaming drill bit below the pilot hole, and reaming from bottom to top; 3) dismantling the raise borer and carrying out the shaft locking construction; during the shaft locking construction, firstly excavating the foundation pit and then carrying out the foundation pit slope support; 4) Excavation and support construction of the shaft; 5) Install lifting suspension system, signal, lighting, wind and water pipelines, and drainage pipelines in the shaft; 6) The vertical shaft is excavated and supported to the bottom of the shaft in full section; during the construction of steps 2) to 6), the slag falls through the guide hole to the connecting air duct of the tunnel main tunnel and is transported out through the slag discharge equipment; 7) Assemble the slipform at the bottom of the shaft and construct the slipform to the designed elevation; 8) Dismantle the slipform machine, clean up the site, and conduct completion acceptance.

2. The highway tunnel shaft pilot shaft expansion construction method according to claim 1, Features: The centralizer is used when drilling the pilot hole and expanding the hole.

3. The highway tunnel shaft pilot shaft expansion construction method as claimed in claim 1, Features: In the step 5), the lifting suspension system comprises a shaft frame (7), a lifting cage (8), a safety plate (1), a wellhead plate (2) and a lifting winch (9); the shaft head of the shaft is connected to the wellhead plate (2); the shaft frame (7) and the lifting winch (9) are respectively installed on one side of the shaft head of the shaft; the safety plate (1) is installed in the shaft of the shaft; the lifting cage (8) is placed on the safety plate (1); the safety plate (1) and the lifting cage (8) are both connected to a set of lifting ropes; the two sets of lifting ropes are both connected to the lifting winch (9) after passing through the wellhead plate (2) and the shaft frame (7) in sequence.

4. The highway tunnel shaft pilot shaft expansion construction method as claimed in claim 3, Features: The safety plate (1) comprises a steel frame (1.1) and an iron plate (1.2); the iron plate (1.2) is horizontally connected to the steel frame (1.1); and a rigid guardrail is arranged on the outer periphery of the steel frame (1.1).

5. The highway tunnel vertical shaft pilot shaft expansion construction method as claimed in claim 1, Features: A movable cover door (1.3) is arranged and connected in the middle of the steel frame (1.1).

6. The highway tunnel vertical shaft pilot shaft expansion construction method as claimed in claim 1, Features: The step 6) comprises the following steps: first, excavating and blasting a shaft of a certain depth from top to bottom, allowing the blasting slag to flow into the connecting air duct of the main tunnel of the shaft bottom through the guide shaft; after the slag is discharged, installing anchor rods in the shaft, installing arch frames on the anchor rods, installing steel mesh on the arch frames, and finally spraying concrete to complete the full-section excavation and support of a section of the shaft; repeating the above steps to complete the full-section excavation and support of the vertical shaft to the shaft bottom.

7. The highway tunnel vertical shaft pilot shaft expansion construction method as claimed in claim 1, Features: When the slag cannot slide smoothly in the guide hole and blockage occurs, the blockage is removed by dredging with a geological drill, water storage punching or reverse drilling.

8. The highway tunnel vertical shaft pilot shaft expansion construction method as claimed in claim 1, Features: The drainage pipeline comprises a plurality of longitudinal water pipes (3) and a plurality of transverse water pipes (4), wherein the plurality of longitudinal water pipes (3) are longitudinally distributed at intervals along the circumferential outer side of the support of step 4), and the plurality of transverse water pipes (4) are transversely arranged at intervals from top to bottom along the outer side of the support of step 4), and the longitudinal water pipes (3) are perforated corrugated pipes.

9. The highway tunnel vertical shaft pilot shaft expansion construction method as claimed in claim 8, Features: Waterproof plates (5) are connected to the outer sides of the plurality of longitudinal water pipes (3) and the plurality of transverse water pipes (4).

10. The highway tunnel vertical shaft pilot shaft expansion construction method as claimed in claim 8, Features: The longitudinal water pipe (3) and the transverse water pipe (4) are connected via a cross-joint (6).

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