A blasting hole arrangement structure for water conveyance tunnel and a rapid construction method

Abstract

The application discloses a kind of water tunnel blasting hole structure for conveying water and quick construction method, it includes the following steps: S1: climbing section excavation support construction: including excavation construction, support construction, climbing section bottom excavation and climbing section secondary lining;S2: shield disassembly hole section excavation support construction: including excavation construction, support construction.The application adopts four steps nine steps to carry out excavation, overcomes the unsafe factors caused by the need to remove temporary support and stress conversion of CD and CRD method, can timely adjust closure time, facilitates mechanized construction, is beneficial to construction process conversion, overcomes the shortcomings of heavy initial support arch frame, difficult installation.

Description

Technical Field

[0001] This invention relates to the field of tunnel technology, specifically to a blasting hole layout structure and rapid construction method for water conveyance tunnels. Background Technology

[0002] The drill-and-blast method is most commonly used in tunnel excavation, and its quality directly determines the safety and economy of tunnel construction. Due to the complex construction environment of water conveyance tunnels, on-site construction personnel often determine the angle, depth, and number of boreholes based on personal experience and ease of construction. This leads to unscientific borehole quantity and layout, increased labor and time investment, and frequent over- and under-excavation during blasting, resulting in reduced integrity of the surrounding rock and increased on-site construction risks, as well as increased workload and cost for secondary lining. Therefore, there is an urgent need for a borehole layout method for water conveyance tunnel blasting that improves excavation progress, excavation quality, construction safety, and economic efficiency.

[0003] In addition, for the construction of large-section tunnels, patent CN115929327A discloses a construction method for large-section tunnels. The method mainly includes the following steps: First, the station cross-section is divided into three excavation units: left, middle, and right. The left unit has pilot tunnels numbered 1, 3, and 5 from top to bottom; the right unit has pilot tunnels numbered 2, 4, and 6 from top to bottom; and the middle unit has pilot tunnels numbered 7, 8, and 9 from top to bottom. Second, after the excavation and support of pilot tunnels 3 and 4 of the station's main structure are completed, temporary cross bracing is erected. One side of the pilot tunnel is connected with high-strength bolts via a pre-reserved connecting plate in the middle partition wall, while the other side is chiseled open to expose the main grid steel frame through shotcrete. Third, the temporary cross bracing is embedded into the grid steel frame, and concrete is poured to form an integral part of the initial support of the main structure. The process involves five steps: First, laying steel mesh, welding connecting bars, welding temporary cross braces to the connecting bars, and finally pouring C15 concrete to form an integral part of the initial station support. Second, installing tie rods above the temporary cross braces, drilling holes in the middle partition wall of section 1 through the 7th guide tunnel to the middle partition wall of section 2, inserting reinforcing bars, threading both ends of the bars, grouting the holes, constructing corbels on the middle partition walls of sections 1 and 2, welding them to the steel frame, using double-section I-beams welded to the corbels, filling the gaps between the corbels and the initial support surface with wooden wedges, and using high-strength bolts to connect the reinforcing bars to the corbels for stress distribution. Third, after completion, continuing to excavate the guide tunnels on both sides to the bottom, excavating guide tunnel No. 7, removing the tie rods, erecting temporary cross braces, connecting them with connecting plates, and pouring concrete to form an integral part of the temporary cross braces on both sides. The drawbacks include: complex construction design and long preparation time; the construction design is not suitable for weak or fractured surrounding rock strata, and is prone to collapse.

[0004] Patent CN109736844B discloses a rapid construction method for initial support of tunnels. It involves installing a concrete spraying arm (1) and two arch frame mounting arms (2) on an arch spraying trolley. The front end of the concrete spraying arm (1) is equipped with a spraying device (3), which is connected to a pumping system (5). The front end of the arch frame mounting arm (2) is equipped with a gripping mechanism (4). Both the front end of the concrete spraying arm (1) and the arch frame mounting arm (2) are equipped with a basket. The method has the following problems: (1) It focuses too much on the research of tunnel support construction machinery and the innovation of support methods, without considering the actual construction situation, and the cost is too high when it is actually applied; (2) The construction steps of using this machinery are too complicated and cumbersome, and the requirements for the coordination between each process are too high, making it difficult to operate in actual construction. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects in the prior art and provide a blasting hole layout structure and rapid construction method for water conveyance tunnels, which can effectively solve the above-mentioned problems in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is to provide... A hole-laying structure for blasting in water conveyance tunnels. The tunnel cross-section is divided into an upper bench, a middle bench, and a lower bench from top to bottom; the upper bench is divided into at least three parts; the middle bench and the lower bench are each divided into at least two parts. The upper step is provided with slotting holes, auxiliary holes, bottom holes and peripheral holes on each part; The middle and lower steps are provided with intermediate eyes, auxiliary eyes, bottom eyes and peripheral eyes; By setting the location of the slot or intermediate slot, then arranging the peripheral and bottom slots, and finally arranging the auxiliary slots according to the cross-sectional size.

[0007] Furthermore, the upper step is composed of a C-shaped cross section at the top and a D-shaped cross section at the bottom. The C-shaped cross section is divided into three parts, namely, part ②, part ① and part ③ from left to right. The D-shaped cross section is divided into two parts, namely, part ⑤ and part ④. The middle steps are divided into two parts, from left to right: part ⑦ and part ⑥. The steps are divided into two parts, from left to right: part 9 and part 8.

[0008] Furthermore, the cut holes are arranged slightly below the center of the excavation face; the peripheral holes are arranged on the outline of the tunneling section and meet the requirements of smooth blasting, with an outward inclination of 0.03-0.05.

[0009] Furthermore, the slotting holes are wedge-shaped, the auxiliary holes are evenly distributed in a plum blossom pattern, and the peripheral holes are light-burst holes.

[0010] Furthermore, both the slotted eye and the auxiliary eye are loaded with uncoupled continuous explosives, while the peripheral eye is loaded with uncoupled intermittent explosives; and the peripheral eye is loaded with explosives at intervals by small explosive rolls tied to bamboo strips.

[0011] Furthermore, the upper step adopts a two-stage wedge-shaped groove, with each groove eye hole having a depth of 0.8m; the auxiliary eye holes have a depth of 0.5m and a row spacing of 0.7m; the peripheral eyes are light-burst holes with a hole spacing of 0.45m and a hole depth of 0.5m; The hole arrangement for the middle and lower steps is as follows: row spacing is 0.8m, auxiliary hole spacing is 0.7m, and peripheral hole spacing is 0.45m.

[0012] A method for rapid construction of water conveyance tunnels includes the following steps: S1: Excavation and support construction of the climbing section: including excavation construction, support construction, bottom excavation of the climbing section and secondary lining of the climbing section; S2: Excavation and support construction of the tunnel section for shield dismantling: including excavation construction and support construction.

[0013] Furthermore, in the excavation and support construction steps of the climbing section, The excavation work includes: (1) The full-section method was used for excavation; (2) Use a hand-operated pneumatic drill for drilling and blasting, and design a smooth blasting profile; (3) On-site handling; The support excavation construction includes: Construction preparation → Steel support → Anchor bolt installation → Rebar mesh and connecting bars installation → Mortar anchor bolt and advanced small guide pipe installation → Shotcrete installation to design thickness → Next cycle of excavation and support; The excavation at the bottom of the climbing section includes: The unexcavated part at the bottom of the climbing section is excavated simultaneously with the excavation of sections 6, 7, 8, and 9 of the dismantling tunnel. Steel arch frames of the same type as the upper arch frame are installed, steel mesh is laid, longitudinal connecting bars are welded, and system anchor bolts and locking foot anchor bolts are installed in sections of each arch frame. Spray concrete support is provided in a timely manner. The secondary lining of the climbing section includes: The secondary lining of the transition section was cast using a transport tunnel secondary lining trolley, and the top cavity was backfilled with lightweight concrete.

[0014] Furthermore, in the excavation and support construction of the shield tunnel dismantling section, the excavation construction includes: (1) The excavation is carried out in four steps and nine stages, and the hole is anchor-type; (2) Use a hand-operated pneumatic drill for drilling and blasting, and design a smooth blasting profile; (3) On-site handling.

[0015] Furthermore, during the excavation and support construction of the shield tunnel dismantling section, the support construction steps are as follows: After the first section is excavated and supported, the second section will be excavated and supported after the first section is excavated and supported for 5-10m. The construction method is the same as the first section. When the third section is excavated, the arch frame at the corresponding position of the first section will be firmly supported with DN89 steel pipes. When the fourth section is excavated, the temporary support between the first and third sections will be extended to the bottom of the fourth section. When the fourth and fifth sections are excavated, temporary transverse supports will be added at the bottom. The excavation and support are carried out in four stages and nine steps, with the excavation and support of sections ①-⑨ carried out sequentially. The interval between each section is 5-10 meters.

[0016] The advantages and beneficial effects of this invention are as follows: (1) The climbing section excavation support and shield tunneling excavation support in this invention have a complete system. The initial support is made of steel arch frame, steel mesh, anchor bolt and shotcrete, which is combined with advanced support to form a complete tunnel support system, which effectively resists the deformation of the surrounding rock.

[0017] (2) The present invention adopts four steps and nine steps for excavation, which overcomes the unsafe factors caused by the need to remove temporary support and force conversion in CD and CRD methods; the closing time can be adjusted in time, which is convenient for mechanized construction and facilitates the conversion of construction procedures; and overcomes the disadvantages of the initial support arch frame being heavy and difficult to install.

[0018] (3) The invention can detect problems in time through the climbing section secondary lining, ensuring construction safety and quality; the main force is transferred to the foundation by the vertical standard section, and the force form is more stable; assembly and disassembly are carried out on the ground, avoiding the safety hazards of disassembly at high altitude.

[0019] (4) The present invention excavates the bottom of the climbing section, and the reserved openings are only at the standard section of the column, making the installation more convenient; the installation is time-saving, labor-saving and material-saving; the impact of the scaffolding and formwork support on the construction progress of the main structure is reduced, and the work efficiency is greatly improved.

[0020] (5) In this invention, the slotting hole can create favorable conditions for the rock of the working face to be broken down and for the arrangement of other blasting holes; the auxiliary hole is to expand the slot cavity blasted out by the slotting hole, creating favorable conditions for the blasting of the peripheral holes; the peripheral holes are used to control the forming profile of the tunnel cross section; the bottom hole is used to blast and level the bottom of the tunnel.

[0021] (6) The present invention sets auxiliary holes and peripheral holes around the cut hole before blasting excavation. The tunnel construction method of the present invention sets the cut hole as the free face, so it can replace the inclined hole cut during blasting. At the same time, it can effectively increase the excavation advance per cycle during blasting, which can greatly improve the excavation speed and shorten the construction period. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a blasting hole layout structure for a water conveyance tunnel according to the present invention; Figure 2 This is a schematic diagram of the detonation network structure; Figure 3 This is a schematic diagram of the propellant loading structure; Figure 4 This is a schematic diagram of the first structure for the excavation and support of the climbing section; Figure 5 This is a schematic diagram of the second structure for the excavation and support of the climbing section; Figure 6 This is a schematic diagram of the third structure for the excavation and support of the climbing section; Figure 7 This is a schematic diagram of the fourth structure for the excavation and support of the climbing section; Figure 8 This is a schematic diagram of the excavation structure for the tunnel section during shield tunneling dismantling; Figure 9 This is a schematic diagram of the support structure for the tunnel section during shield tunneling dismantling; Figure 10 This is a diagram showing the steps involved in dismantling and excavating the tunnel section of a shield tunnel. Figure 11 This is a diagram of the arch frame of the tunnel section being dismantled by the shield tunneling machine. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0024] like Figure 1 As shown, a blasting hole layout structure for water conveyance tunnels is described. The tunnel cross-section is divided into an upper bench, a middle bench, and a lower bench from top to bottom; the upper bench is divided into at least three parts; the middle bench and the lower bench are each divided into at least two parts. The upper step is provided with slotting holes, auxiliary holes, bottom holes and peripheral holes on each part; The middle and lower steps are provided with intermediate eyes, auxiliary eyes, bottom eyes and peripheral eyes; By setting the location of the slot or intermediate slot, then arranging the peripheral and bottom slots, and finally arranging the auxiliary slots according to the cross-sectional size.

[0025] Cut-out holes: create favorable conditions for the rock to break down from the working face and for the arrangement of other blast holes; auxiliary holes are used to expand the cavity blasted out by the cut-out holes, creating favorable conditions for the blasting of the surrounding holes; the function of the surrounding holes is to control the forming contour of the tunnel cross section; the function of the bottom hole is to blast and level the bottom of the tunnel.

[0026] like Figure 10As shown, the upper step is composed of a C-shaped cross section at the top and a D-shaped cross section at the bottom. The C-shaped cross section is divided into three parts, namely ②, ① and ③ from left to right. The D-shaped cross section is divided into two parts, namely ⑤ and ④. The middle steps are divided into two parts, from left to right: part ⑦ and part ⑥. The steps are divided into two parts, from left to right: part 9 and part 8.

[0027] The cut holes are located slightly below the center of the excavation face; the peripheral holes are located on the outline of the excavation section and meet the requirements of smooth blasting, with an outward inclination of 0.03-0.05. The opening of the bottom hole should be about 15cm higher than the designed level of the bottom plate, and the bottom of the hole should reach 10cm-20cm below the level of the bottom plate to prevent under-excavation. The hole spacing and resistance line are the same as those of the auxiliary holes.

[0028] Based on the rock-breaking law of blasting shock waves and the actual requirements of this project, during tunnel blasting, the cut holes are wedge-shaped, the auxiliary holes are evenly distributed in a quincunx pattern, and the peripheral holes are smooth blasting holes.

[0029] The upper step adopts a two-stage wedge-shaped groove; the auxiliary eye holes are 0.5m deep and 0.7m apart; the peripheral eyes are light-burst holes with a hole spacing of 0.45m and a hole depth of 0.5m; The hole arrangement for the middle and lower steps is as follows: row spacing is 0.8m, auxiliary hole spacing is 0.7m, and peripheral hole spacing is 0.45m.

[0030] Figure 1 The distribution of slots, intermediate slots, auxiliary slots, bottom slots, and peripheral slots in each part (unit: mm) is shown in the table below: In section ①, the cut holes are symmetrically arranged in the lower center of the excavation face. The first group of cut holes is arranged symmetrically in pairs, and the second group of cut holes is arranged symmetrically in groups of three outside the first group of cut holes. The distance between the first group of cut holes and the second group of cut holes is 0.4m. There are two sets of auxiliary holes. The first set of auxiliary holes is located outside the second group of cut holes, and the second set of auxiliary holes is located outside the first group of auxiliary holes. The distance between the first set of auxiliary holes and the second set of auxiliary holes is 0.7m. The peripheral holes are arranged on the outline of the excavation section. The peripheral holes are located outside the second auxiliary holes, and the distance between the peripheral holes and the second auxiliary holes is 0.6m. The bottom hole is located at the bottom of section ①.

[0031] ① Blasting Parameter Table

[0032] In section ②, the arrangement of the slotting holes, auxiliary holes, peripheral holes, and bottom holes is as follows: Figure 1 As shown in the table below, ② Blasting Parameter Table

[0033] In section ③, the arrangement of the slotting holes, auxiliary holes, peripheral holes, and bottom holes is as follows: Figure 1 As shown in the table below, the arrangement of the cut holes is similar to that of section ①, with the peripheral holes arranged on the outline of the excavation section; the bottom holes are arranged at the bottom of section ②, and finally, auxiliary holes are arranged according to the size of the section.

[0034] ③ Blasting Parameter Table

[0035] In sections ④-⑨, several intermediate eyes are arranged horizontally to form groups, and several intermediate eye groups are arranged longitudinally and parallel within each section. The peripheral eyes are arranged on the outline of the tunneling section. The bottom eyes are arranged at the bottom of each section, and finally, auxiliary eyes are arranged according to the size of the section.

[0036] ④ Blasting Parameter Table

[0037] ⑤ Blasting Parameter Table

[0038] ⑥ Blasting Parameter Table

[0039] ⑦ Blasting Parameter Table

[0040] ⑧ Blasting Parameter Table

[0041] ⑨ Blasting Parameter Table

[0042] like Figure 2 As shown, the detonation network structure includes an in-hole detonator, a detonating detonator, a trigger detonator, and a detonating needle. The in-hole detonator is connected to the trigger detonator through the detonating detonator, and the trigger detonator is connected to the detonating needle. To ensure accurate and reliable detonation, a compound network of plastic detonating cord detonators is used. Each detonator is equipped with two detonators, and the cords are not knotted or stretched during connection. Each cluster of detonators connected to each detonator has the same number of detonators, ≤20. The detonators are wrapped with electrical tape. After the network is connected, it is inspected and accepted by a designated person; detonation can only proceed after everything is confirmed to be correct.

[0043] like Figure 3As shown, both the cut holes and the auxiliary holes use uncoupled continuous charges, while the peripheral holes use uncoupled interval charges; and the peripheral holes are filled with small explosive cartridges tied to bamboo strips at intervals. Pouring the boreholes can improve the energy utilization rate of the explosives, thereby reducing the amount of explosives used and lowering the blasting vibration effect. All charged boreholes are plugged with stemming material to ensure the quality of the plugging. The uncharged portion of the cut holes is completely plugged, and the plugging length of the remaining excavation holes is greater than 80% of the resistance line. The stemming material is made of 2 / 3 sand and 1 / 3 loess and is water-based.

[0044] A method for rapid construction of water conveyance tunnels includes the following steps: S1: Excavation and support construction of the climbing section: including excavation construction, support construction, bottom excavation of the climbing section and secondary lining of the climbing section; S2: Excavation and support construction of the tunnel section for shield dismantling: including excavation construction and support construction.

[0045] 1. Step S1, the excavation and support construction of the climbing section, includes: (1) Excavation construction, such as Figure 4 As shown ① The full-section method was used for excavation. The excavation section size was 7.8m x 7.5m. The tunnel type was a city gate tunnel. The excavation slope ratio was 1:3.125, which means that the elevation of each arch frame increased by 0.259m.

[0046] ② Excavation will be carried out using a hand-operated pneumatic drill and blasting method, with smooth blasting along the designed outline. The surrounding rock of the tunnel is classified as Class IV. Each excavation cycle will advance between 0.8 and 1.0 meters, with the specific advance determined based on the actual surrounding rock conditions.

[0047] ③ On-site handling: After each blast, a backhoe is used for safety handling. The excavated slag is transported to the designated slag yard by a 2.0m³ side-dump loader loaded with 20t dump trucks.

[0048] (2) Support construction The support construction procedure is as follows: construction preparation → steel support → anchor bolt installation → steel mesh and connecting bars installation → mortar anchor bolt and pre-installed small guide pipe installation → shotcrete installation to design thickness → next cycle of excavation and support. Details are as follows: ①The surrounding rock category is IV. The steel arch frame is an HW150x150 type steel arch frame. Each frame is assembled in 5 sections. The spacing between the arch frames is 0.8m. The arch frame is connected using M22x80, 8.8 grade high-strength bolts. There are 16 sets in total for each arch frame. The arch frame connection must be welded. The weld must be full and the bolt connection must be firm.

[0049] ② The verticality deviation of the steel arch frame shall not exceed ±2 degrees, and the spacing deviation shall not exceed ±5cm; the elevation of the arch frame shall be strictly controlled, and the deviation shall not exceed ±5cm.

[0050] ③ The arch frame should be placed on intact rock. If the surrounding rock is broken, the loose debris at the arch foot should be cleaned and backfilled with shotcrete. The arch frame should be as close to the rock surface as possible. If any rock falls off, it should be backfilled with shotcrete to ensure compaction. Voids are strictly prohibited. ④ The reinforcing mesh is made of φ8mm plain round steel bars welded into a mesh. When supporting Class IV surrounding rock, the mesh size is 200×200mm. The width of the mesh is prefabricated according to the spacing of the steel arch frames, as required by the design. The size of the processed mesh should meet the design requirements. The size of the mesh is determined by the arch frame spacing and ease of operation. Each reinforcing mesh is secured with anchor bolts to ensure that the mesh is tightly attached to the tunnel wall. Adjacent reinforcing meshes should overlap, and the longitudinal and transverse reinforcing meshes should correspond during the overlap. The overlap length should not be less than 200mm.

[0051] ⑤ After the steel arch frame is erected, each section end is secured with locking anchor bolts (C22, L=2.5m, driven at a downward inclination of 15 degrees), and cement mortar with a strength grade of not less than 20Mpa is poured in. At each point, the ends of two anchor bolts are bent 10cm and welded to the left and right sides of the steel arch frame respectively. The ends of the anchor bolts are welded to the arch frame. If the locking anchor bolts and system anchor bolts are in the same position, the locking anchor bolts can replace the system anchor bolts.

[0052] ⑥ The system anchor bolts adopt full-length bonded cement mortar anchor bolts. C22 steel bars are processed to 3m lengths according to design requirements, with the ends ground down. The anchor bolt tails are threaded using a threading machine, with a thread length of 10cm. The backing plate is 15cm x 15cm x 8mm (length x width x thickness). The anchor bolt spacing is 0.8m, arranged in a staggered pattern, with a hole position deviation not exceeding 100mm. Anchor bolt holes are drilled using a pneumatic drill, with the hole depth meeting design requirements and exceeding the depth by no more than 10cm. The anchor hole diameter should be at least 20mm larger than the anchor bolt diameter. Grouting: Cement mortar mix ratio: water:cement = 1:1 to 1:2. The cement mortar strength grade should not be lower than 20MPa. Cement mortar should be prepared and used immediately. Install the support plate at the end of the anchor bolt, ensuring the support plate is tightly against the rock surface. Immediately after the anchor bolts are installed, they should not be struck or have heavy objects suspended from them.

[0053] ⑦ The connecting bars are C22 steel bars, which are welded to the inside of the arch frame. When cutting the bars, adjust them according to the arch frame spacing, and make them 2-3cm shorter than the arch frame spacing. The bars must be welded firmly.

[0054] ⑧ The arch crown is reinforced with 180° grouting using φ42 pre-drilled small guide pipes. The guide pipes are 3.0m long, with a circumferential spacing of 0.3m and a longitudinal overlap length of 1.0m. The small guide pipes are made of φ42mm hot-rolled seamless steel pipes with a wall thickness of 3.5mm. The front end is made into a pointed cone shape, and the tail end is welded with φ8mm steel reinforcement. Holes with a diameter of 6-8mm are drilled every 10-20cm in a staggered pattern on the pipe wall. The tail end is not less than 30cm long and serves as a non-drilled grout-stopping section.

[0055] (3) Excavation of the bottom of the climbing section like Figure 5As shown, the unexcavated portion at the bottom of the climbing section is excavated simultaneously with the excavation of sections ⑥, ⑦, ⑧, and ⑨, and HW150x150 steel arch frames of the same type as the upper arch frame are installed. Steel mesh is laid, longitudinal connecting bars are welded, and system anchor bolts and locking anchor bolts are installed in sections of each arch frame. Shotcrete support is applied promptly.

[0056] (4) Secondary lining of the climbing section like Figure 6 and Figure 7 As shown, the secondary lining of the 20m transition section is still poured using a transport tunnel secondary lining trolley, and the top cavity is backfilled with lightweight concrete.

[0057] 2. Step S2, the excavation and support construction of the shield tunnel dismantling section, includes: (1) Excavation construction ①For example Figure 8 As shown, the excavation is carried out in four steps and nine stages, with an anchor-type tunnel and an excavation cross-section of 14.5m x 15.949m. After entering the shield dismantling section, the road surface of the climbing section is first repaired, and a temporary ramp is built to ensure convenient excavation and transportation needs at the top of the dismantling tunnel. Excavation of section ① is carried out first, and temporary support arches are erected on both sides for shotcreting and sealing. After normal excavation of section ①, sections ②-⑨ are excavated in sequence in four steps.

[0058] ② Hand-operated pneumatic drills and blasting were used for excavation, with smooth blasting along the designed outline. The surrounding rock of the tunnel is classified as Class IV and has a large cross-section. Sections ① to ⑤ have a single-cycle advance of 0.5m, and sections ⑥ to ⑨ have a single-cycle advance of 1.0m. Mechanical excavation was used when the surrounding rock was poor.

[0059] ③ After each blast, a backhoe is used for safety handling. The excavated slag is transported to the designated slag yard by a 2.0m³ side-dump loader loaded with 20t dump trucks.

[0060] (2) Support construction like Figure 9As shown, the shield tunnel dismantling section support adopts HW150x150 full-ring steel arch frames, each frame assembled in 17 sections. The arch frames are spaced 0.5m apart and fitted with double-layer Φ8 steel mesh. C22 connecting bars are installed longitudinally between the arch frames, with a circumferential spacing of 1m. Φ42 pre-grouting guide pipes, 3m long, are installed in the arch, with a circumferential spacing of 0.3m and a longitudinal spacing of 1.0m. When the surrounding rock is fractured or water seepage affects excavation stability, grouting pre-reinforcement is performed on the face and arch crown. The system anchors are C25 mortar anchors, spaced 0.8m apart. The arch mortar anchors (0.8m exposed) are installed at intervals of L=6.8m and L=4.8m, arranged in a staggered pattern. The sidewall mortar anchors (0.5m exposed) are installed at intervals of L=6.5m and L=4.5m, also arranged in a staggered pattern. Each arch section has one set of C22 anchor bolts installed at both ends. The anchor bolts are 3m long, installed at a 30° angle, and firmly welded to the arch frame. C30 polyvinyl alcohol fiber reinforced concrete is then sprayed on, with a thickness of 25cm.

[0061] The support steps are as follows: like Figure 10-11 As shown, after the excavation of section ①, a double-layer steel mesh of Φ8@150x150 is installed, and HW150x150 steel arch frames are installed, along with temporary arch frames on both sides. The arch frames are connected as a whole by longitudinal connecting steel bars. Immediately after the arch frames are installed, anchor bolts are driven (the anchor bolt arrangement is shown in the figure below, where each line segment represents one set of anchor bolts), system anchor bolts, and pre-grouting small guide pipes for the arch are installed. After acceptance by the supervising engineer, shotcreting is carried out. To ensure construction safety, section ② is excavated and supported 5-10m after section ① is excavated and supported, using the same construction method as section ①. When section ③ is excavated, the corresponding arch frames in section ① are first firmly supported with DN89 steel pipes. When section ④ is excavated, the temporary supports between sections ① and ③ are extended to the bottom of section ④. Temporary transverse supports are added at the bottom when sections ④ and ⑤ are excavated. Sections ①-⑨ are excavated and supported in nine steps across four stages, with an interval of 5-10 meters between each section. The excavation process should follow the principles of "short advance, weak blasting, strong support, and frequent measurement," and anchor bolts and advanced small guide pipes should be grouted in a timely manner.

[0062] 3. The specific excavation process for steps S1 and S2 is as follows: (1) Excavation preparation The ventilation, water, and electricity supply inside the cave are ready, and construction personnel and equipment are in place.

[0063] (2) Measurement and setting out The traverse control network surveying inside the tunnel was conducted using a total station equipped with a level. Construction surveying was generally performed using a total station, while infrared laser positioning technology was used for setting out the rock anchor beams. Surveying operations were carried out by professionals; after each blast, the tunnel centerline and design specification lines were laid out, and borehole positions were determined according to the blasting design parameters. Excavation cross-section measurements were conducted before shotcreting, with a measurement interval of 3 meters. Regular comprehensive inspections and re-measurements of the tunnel axis were performed to ensure the quality of the surveying control process. Simultaneously, as the tunnel excavation and support progressed, a station marker was placed every 20 meters on both sides of the tunnel walls and the tunnel roof. The surveying control points inside the tunnel were firmly embedded and concealed, and properly protected to prevent damage from machinery.

[0064] (3) Drilling operations Qualified drillers strictly adhere to the centerline, waistline, excavation outline, and borehole layout determined by surveying. Each driller is assigned to a specific area and location for drilling, implementing a strict quality and economic responsibility system for drilling operations. Technical personnel are present on-site to facilitate timely identification and resolution of technical issues. Each row of blasts is inspected by the on-duty engineer according to the requirements of "level, straight, and aligned," ensuring that the bottom of the blast holes falls on the same vertical cross-section specified for blasting (horizontal plane for stepped blasting). To minimize over-excavation, the external deviation angle of peripheral holes is controlled to the minimum angle achievable by the equipment. The deviation of smooth blasting holes, pre-splitting holes, and cut holes must not exceed 5cm, and the deviation of other blast hole positions must not exceed 10cm.

[0065] (4) Loading, wiring, and detonation Before loading explosives, the borehole is flushed with high-pressure air. Only after the borehole has passed inspection can explosive loading and blasting be carried out. The loading, plugging, and connection of the detonation circuit of the borehole shall be carried out by qualified blasters in strict accordance with the approved drilling and blasting design. Explosive loading shall strictly comply with the blasting safety operation procedures.

[0066] Skilled blasters are responsible for loading explosives into the slotting holes. For the smooth blasting holes and pre-splitting holes, small explosive cartridges are tied to bamboo strips and loaded at intervals. During excavation, a drilling rig is used as an elevated platform for loading explosives. The explosives in the slotting holes, enlarged holes, and other blasting holes must be packed tightly and properly sealed. Loading must be carried out strictly according to the blasting design drawings (blasting parameters are continuously adjusted and optimized during implementation). Magnetoelectric detonators are used to connect the detonation network. Finally, the blasters and the on-duty technician review and check the process. Once everything is confirmed to be correct, personnel and equipment are evacuated, and the blasters are responsible for detonation.

[0067] (5) Ventilation, smoke dispersal and dust removal Ventilation equipment was continuously activated throughout the excavation of each chamber, and the ventilation system was used to remove smoke and dust, ensuring that the concentration of harmful gases was reduced to within permissible limits within a specified time after blasting. After the blasting smoke dissipated, water was sprayed onto the blasting debris pile at the excavation face to suppress dust.

[0068] (6) Safety handling Throughout the construction process, a dedicated safety officer oversees the entire operation. After blasting, excavators are used to remove any remaining loose rocks and debris from the tunnel face and side arches to ensure the safety of personnel and equipment. For sections with fractured rock surfaces, a 5cm thick layer of concrete can be sprayed after safety treatment. Before erecting the scaffolding, the foreman directs workers to manually remove hazards. Construction personnel stand in safe areas with completed supports and use steel bars or anchor bolts for comprehensive manual hazard removal. After shotcreting, mechanical hazard removal is conducted again, and the team leader and dedicated safety officer must inspect and confirm before proceeding to the next cycle of construction. During construction, the stability of the surrounding rock in the excavated sections is frequently checked, and any loose rock blocks that may collapse are pried away.

[0069] (7) Slag removal and bottom cleaning After each blast, a backhoe is used for safety procedures. Excavation of the slag material uses a 2.0m... 3 A side-dump loader loaded 20-ton dump trucks to transport the waste to the designated slag yard. After the slag was removed, an excavator was used to go deep into the hazard removal area. During the hazard removal, the shift leader supervised the operation to ensure that the hazard was completely removed and to prepare for the next cycle of drilling and blasting operations.

[0070] (8) Surrounding rock support After each blasting operation is completed, random anchoring and spraying support and systematic support should be carried out in a timely manner for local rock masses with poor stability. In areas with good surrounding rock, systematic anchor bolts, wire mesh and shotcrete can be installed after the excavation operation. Before the initial support, manual hazard removal must be carried out again to ensure that the hazard removal is thorough before proceeding with the erection of frames, anchor bolt support and other procedures.

[0071] 4. The support construction process in steps S1 and S2 includes mortar anchor bolt construction, wire mesh and shotcrete construction, steel support construction, and pre-grouting small guide pipe construction. The specific process is as follows: (1) Construction process of mortar anchor bolts Before anchor bolt installation, on-site tests of the anchor bolts are conducted, mainly including the following anchor bolt tests: ① Screen 2-3 mortar mix proportions that meet the design requirements through indoor tests, and prepare test outlines for approval to conduct production tests.

[0072] ② Grouting Compaction Test: Select anchor rods and plastic pipes (or steel pipes) with the same diameter, length, anchor hole diameter, and inclination as the on-site anchor rods. Use cement grout or cement mortar mixed with the same materials and proportions as the on-site grouting, and perform grouting according to the same grouting process as the on-site construction. After curing for 7 days, dissect the pipe to check its compactness. Tests must be conducted for anchor rods of different types and lengths. The test plan must be submitted to the supervisor for approval, and the test must be conducted according to the approved plan, with the supervisor present during the test. The grouting compactness of the test section should not be less than 90%. Otherwise, the test process needs to be further improved before conducting the test again until the grouting compactness reaches 90% or higher. Actual construction must strictly follow the grouting process approved by the supervisor.

[0073] Only after the on-site anchor bolt test is completed can normal anchor bolt construction proceed. The main procedures are as follows: ① Hole making a. For ordinary mortar anchor bolts, the borehole diameter should be larger than the anchor bolt diameter by at least 20mm. a. The drill bit must meet the requirements, the drilling point must be clearly marked, and the deviation of the hole position in any direction should be less than 100mm. For rock anchor beams, the vertical hole position deviation should not exceed ±30mm, and the horizontal hole position deviation should not exceed ±100mm.

[0074] b. The direction of the anchor bolt hole axis must meet the requirements of the construction drawings. The direction of the hole axis of the system anchor bolts must be perpendicular to the excavation face. The direction of the hole axis of the locally reinforced anchor bolts must be opposite to the inclination of the possible sliding surface, and the angle between the anchor bolts and the sliding surface must be greater than 45°. The borehole azimuth deviation must not exceed 5°. The anchor hole depth must meet the design requirements, and the hole depth deviation must not exceed 50mm.

[0075] c. After drilling is completed, the drilling specifications (diameter, depth and inclination) of the anchor bolt holes shall be checked and recorded. Any unqualified anchor bolts shall be replaced.

[0076] d. After drilling is completed, use a combination of air and water to clean the hole and remove loose rock powder and accumulated water. If it is not necessary to insert the anchor bolt immediately, the hole opening should be plugged for appropriate protection. Before the anchor bolt is installed, the hole should be inspected to determine whether it needs to be cleaned again.

[0077] ② Installation and grouting of anchor bolts a. Insert the anchor rod immediately after filling the borehole with grout; the direction of the anchor rod insertion should be consistent with the direction of the hole, and it should be rotated appropriately during the insertion process (manual twisting or pipe wrench twisting). b. The anchor bolt should be inserted slowly and evenly. When a "springy" feeling is felt, rotate it before inserting it. Avoid hammering during insertion as much as possible.

[0078] ③ Inspection and Acceptance The mortar anchor rods were tested using tensile plate tests.

[0079] After the mortar anchor bolts are installed and reach the designed age, the on-site supervisor will randomly select samples for pull-out tests. The pull-out values ​​must meet the design requirements.

[0080] (2) Construction of shotcrete with wire mesh The shotcrete used inside the tunnel is primarily C30 shotcrete. During construction, a 3cm-5cm thick layer is first sprayed, followed by the laying of a steel mesh, which is then securely connected to anchor bolts and additional reinforcing bars (or expansion bolts). Finally, the shotcrete is applied in 2 to 4 coats to achieve the designed thickness. The mesh is installed manually using a platform truck. The shotcrete is transported to the working face by a mixer truck and applied using a shotcrete spraying machine.

[0081] The main tunnel shotcrete was carried out using the "wet spraying method." The shotcrete work was carried out in parallel and simultaneously with the excavation and anchor bolt construction, following the process flow below: ① Field test Based on past construction experience, indoor tests can be used to optimize and select the shotcrete production process parameters and mix proportions that meet both construction needs and design requirements. The method and steps are as follows: A. Screen 2-3 mix proportions through indoor tests, and prepare test outlines for approval for production trials; B. Select a site (or one designated by the supervisor) and conduct production tests at 6 to 9 representative sites according to the type and location of the surrounding rock. C. According to the design and test outline requirements, spraying operations will be carried out using the selected mix proportions. The spraying range is tentatively set at 10m. 2 (or one unit volume), according to the specifications, set up sufficient wooden molds or bottomless steel molds on the sprayed rock surface (to test compressive strength, tensile strength, impermeability, and bonding strength with the rock surface, etc.), and at the same time, take samples to make standard test blocks according to the test specifications, and cure them under the same conditions; D. Compare the physical properties of specimens that meet the design requirements (including the degree of impact from blasting). E. Organize and analyze test records, and select appropriate mix proportions and construction process parameters by taking into account factors such as rebound rate, strength guarantee rate and construction efficiency, and submit them to the design and supervision unit for approval.

[0082] ②Preparatory work Install spray thickness control markers, ensure sufficient ventilation and lighting in the work area, and inspect all machinery and pipelines before spraying to ensure normal operation. Take appropriate measures to treat any seepage surfaces, prepare treatment materials, and coordinate with relevant parties for surface sampling.

[0083] ③ Mixing and transportation The mixing and batching of materials must be strictly prepared and mixed according to the mix proportions determined by experiments. The mixing time must be sufficient. The mixed materials must be protected from rain and contamination during transportation and storage. They must be strictly sieved before being fed into the machine, and their transportation and storage times must meet relevant technical specifications. The batching and mixing of steel fiber reinforced concrete must be uniform. Shotcrete is transported to the work site by a mixer truck.

[0084] Cement: Ordinary Portland cement is preferred. Special cement may be used with the approval of the supervisor when corrosion protection or other special requirements are needed. The cement strength grade should not be lower than PO42.5. Cement delivered to the site should have a quality certificate from the manufacturer.

[0085] Aggregates: Fine aggregates should be hard and durable coarse and medium sands with a fineness modulus greater than 2.5 and a moisture content of 5-7% when used; coarse aggregates should be durable pebbles or crushed stone with a particle size not greater than 15mm; aggregates containing active silica shall not be used in shotcrete.

[0086] Water: Any drinking water that meets national standards may be used for mixing and curing concrete. Untreated industrial wastewater and domestic sewage must not be used for mixing and curing concrete. Surface water, groundwater, and other types of water must be tested and approved according to current relevant standards before being used for the first time in mixing and curing concrete.

[0087] Admixtures: The quality of quick-setting agents should meet the requirements of the construction drawings and have a quality certificate from the manufacturer. The initial setting time should not exceed 5 minutes, and the final setting time should not exceed 10 minutes. The selection of admixtures should be approved by the supervisor.

[0088] Reinforcing wire mesh: Smooth reinforcing wire mesh with a yield strength of not less than 235MPa is used.

[0089] External admixtures: When external admixtures are required for a project, the dosage should be determined through testing, and the performance of the shotcrete after adding external admixtures must meet the design requirements.

[0090] Use shotcrete within the scope specified in the construction drawings or as instructed by the supervisor. The specific dosage should be determined through testing and approved by the supervisor.

[0091] ④ Clean the rock surface Remove loose rocks, rubble, and debris from the excavation surface; prepare a smooth excavation surface; install a working platform; spray the surface with a high-pressure air gun; and install markers to control the thickness of the sprayed concrete.

[0092] ⑤ Steel mesh According to the construction drawings, a steel mesh is laid before spraying concrete. The spacing of the steel mesh is 150mm, and the steel bars are plain round steel bars with a diameter of 8mm.

[0093] ⑥ Key points of spraying Shotcrete work should be carried out in sections and patches sequentially, with the spraying order from bottom to top to avoid rebound material covering unsprayed areas. When spraying in layers, the next layer should be sprayed after the previous layer has fully set. If spraying is to be carried out more than 1 hour after final setting, the spraying surface should be rinsed with high-pressure water beforehand.

[0094] Spraying operations must strictly adhere to the operating procedures for the spraying machine: material should be continuously supplied to the spraying machine; the working air pressure of the spraying machine should be kept stable; when spraying operations are completed or interrupted for any reason, the accumulated material in the spraying machine and the conveying pipe should be cleaned to prevent pipe blockage.

[0095] To reduce rebound and improve spraying quality, the nozzle should be kept in good working condition. Adjust the air pressure, keep the nozzle perpendicular to the sprayed surface, control the spray distance within the range of 0.6m to 1.2m, and adopt the correct spiral trajectory spraying technique. The sprayed area should be checked for thickness immediately after spraying (via the installation points). If the thickness does not meet the requirements, re-spraying should be performed promptly. Areas with wire mesh should be sprayed until no visible mesh strips remain.

[0096] ⑦ Maintenance and testing Two hours after the final set of the shotcrete, it should be sprayed with water for curing. The curing time should generally not be less than 14 days. Water curing should not be carried out when the temperature is below 5℃. When the air humidity around the shotcrete reaches or exceeds 85%, it can be cured naturally.

[0097] Timely core sampling and testing, timely compilation of test reports, and prompt quality assessment and project quality acceptance. Core samples with a diameter of 100mm shall be taken from designated locations as required by the supervisor for tensile testing, and the test results shall be submitted to the supervisor. All core sampling sites shall be backfilled with dry-hardened cement mortar.

[0098] (3) Steel support construction The upstream shield tunnel dismantling arch frame is designed as HW150x150 with a frame spacing of 0.5m. Each steel support is fabricated in sections, with connecting steel plates at both ends of each section. The sections are connected by bolts, and the connecting steel plates are welded firmly on three sides. After the cross-section is measured, the steel support is erected and closely adhered to the surrounding rock. Gaps are tightened with steel wedges, and the bottom feet on both sides are placed on a solid foundation. The transverse connection uses C22@100cm to increase the overall integrity of the steel support.

[0099] After the steel arch frame is erected, it is locked with anchor bolts (C22 mortar anchor bolts, L=3m). Two anchor bolts are bent 10cm at the end at each point and then welded to the left and right sides of the steel arch frame respectively.

[0100] The construction process for steel supports is as follows: ① Steel frame layout and mold making Different molds are made according to the different radii of the steel profiles. The manufacturing precision of the steel profile frame is controlled by the molds, so the requirements for the manufacturing precision of the molds are high. The main technical indicators for mold manufacturing control are the inner and outer arc lengths, chord lengths, and radii.

[0101] The mold making adopts the on-site layout method. First, the mold pattern is laid out, and then the steel profile is bent out using a steel profile bending machine. Multiple checks are performed until the inner and outer arc lengths, chord lengths, and radii of the steel profile fully meet the design requirements, and the location of the joint plate is accurately found.

[0102] ② Steel frame bending and cutting The steel profiles are 12m in length and are processed using a steel profile bending machine. The extension of the hydraulic cylinder is adjusted appropriately according to the processing radius. During the bending process, experienced workers must operate the motor and provide unified command. After passing through the bending machine, the steel profiles are passed through a mold, and the curvature is checked against the mold. If the curvature does not meet the requirements, the bending is repeated. After bending, the steel profiles are temporarily stored on four identical homemade simple steel bar stools (with rollers).

[0103] After bending one unit, cut one unit at a time. When cutting the steel profile, you can use methods such as measuring the outer arc length and the inner chord length. Use a caliper to control the cutting surface of the steel profile in the radial direction, then draw lines with a pen, and use oxyacetylene welding for cutting. When cutting, the cutting torch must be perpendicular to the steel profile and the cutting surface must be flat. After cutting, grind the protruding edges of the cutting surface.

[0104] Before completing the bending of a single 12m steel section, bending must be paused, and the next 12m steel section must be securely welded to it before continuing bending. Any remaining steel sections processed during the shift must be moved to the storage area and the steel bending machine must be cleaned.

[0105] ③ Welding of connecting plates After the bent steel section is cut, its arc length is checked. If the steel section is too short to weld the connecting plate, it must be lengthened. If the steel section is too long, it must be cut again. Once the arc and length of the steel section meet the design requirements, the connecting plate is placed in the slot. For steel sections where the cutting line deviates very little from the radial direction, the connecting plate is adjusted to ensure that the axis of the connecting plate is in the radial direction. The weld of the connecting plate is controlled according to the specifications. The bolt holes on the connecting plate must be precise. When welding with the steel section, they must be aligned and fixed on the top, bottom, left, and right before welding can proceed. After welding, the bolt holes and the surface of the connecting plate are smoothed to reduce errors during the assembly and connection of the steel section.

[0106] Finished steel profiles should be stored uniformly, and steel frames of different radii and units should be clearly labeled for easy retrieval. Stored steel profiles should be padded with mats and covered with lids. The storage area should be located in a convenient location for easy transport of the steel frames.

[0107] ④ Steel arch frame transportation The steel frames will be transported to the construction site using 8-ton Dongfeng dump trucks. The processing plant must issue the steel frames strictly according to their specifications. Once delivered to the work site, the steel frames must be stored in a dry place and must not be piled on damp ground. They must be clearly labeled. Before erecting the steel frames, the on-duty technician must carefully check their specifications. If the wrong specifications are issued, the frames must be returned immediately and a new one issued.

[0108] ⑤ Steel arch frame installation a. Under-excavation treatment and removal of loose rocks Workers check for under-excavation based on surveying and setting out. For under-excavation within 10cm, the steel frame erection team uses crowbars or pneumatic drills to remove it, while simultaneously prying away loose rocks. For under-excavation greater than 10cm, blasting personnel handle the blasting, and then the steel frame erection team checks for rock looseness, removing any loose rocks to ensure construction safety during steel frame erection. Steel frame erection can only proceed after the under-excavation is completed and approved by on-site technicians.

[0109] b. Erecting the steel arch frame The steel arch frame is erected on a trolley. The steel sections delivered to the site are carried by 1-2 workers to the erection location, with one end secured with a rope. 3-4 workers on the work platform lift the steel sections onto the platform. Construction personnel locate the positioning points according to the steel frame design spacing and technical instructions. The base section of the steel frame is erected first. When erecting the base section, it is lowered onto the work platform, and two workers below adjust the base using the buried reference point to ensure accurate positioning of the steel arch frame. The bottom elevation is strictly controlled; any over- or under-excavation at the bottom must be addressed. The steel base must be firmly supported to prevent deformation of the surrounding rock and subsequent sinking of the steel sections. Simultaneously, each steel support is connected into a whole using longitudinal connectors and welded securely to the anchor bolt heads. The steel sections are erected symmetrically. After the base section is erected, the arch section is erected. When erecting the arch section, first install the M24 connecting bolts (not tightened), use temporary supports to hold the steel section, and connect it to the previous steel section with connecting steel bars. Then, install the other arch section symmetrically. After installation, check the errors of the arch, the two arch feet, and the measuring reference line, make local adjustments, and finally tighten the bolts. The workers first conduct a self-inspection. After passing the inspection, they notify the on-duty technicians for inspection.

[0110] The steel supports should be installed outside the lining design section, and the gap between the back of the steel frame and the rock surface must be filled with shotcrete.

[0111] (4) Construction of advanced grouting small guide pipe Because the tunnel section used for shield tunneling is located in Class IV fractured rock, and the large excavation section is prone to collapse, the arch is reinforced with grouting using φ42 pre-drilled small guide pipes. The guide pipes are made of φ42 seamless steel pipes, 3.0m long, with an external insertion angle of 5-10°, a circumferential spacing of 0.3 meters, and a longitudinal overlap length of not less than 1.0 meter. The small guide pipes are made of φ42mm hot-rolled seamless steel pipes with a wall thickness of 3.5mm. The front end is made into a pointed cone shape, and the tail end is welded with φ8mm steel reinforcement. Holes with a diameter of 6-8mm are drilled every 10-20cm in a staggered pattern on the pipe wall. The tail end is at least 30cm long and serves as a non-drilled grout-stopping section. Pre-exploratory boreholes are conducted when necessary to anticipate harmful gases and water inrush ahead.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A rapid construction method for blasting hole layout structures in water conveyance tunnels, characterized in that, It includes the following steps: S1: Excavation and support construction of the climbing section: including excavation construction, support construction, bottom excavation of the climbing section and secondary lining of the climbing section; S2: Excavation and support construction of the tunnel section for shield dismantling: including excavation construction and support construction; In the excavation and support construction of the tunnel section for shield tunnel dismantling, the excavation construction includes: (1) The excavation is carried out in four steps and nine stages, and the tunnel is anchor-type; (2) Use a hand-held pneumatic drill for drilling and blasting, and design a smooth blasting profile; (3) On-site handling; The excavation and support are divided into four stages and nine steps, with excavation and support of sections ①-⑨ carried out sequentially, and the interval between each section is 5-10 meters. During the excavation and support construction of the tunnel section for shield tunnel dismantling, the support construction steps are as follows: After the first section is excavated and supported, the second section will be excavated and supported after the first section is excavated and supported for 5-10m. The construction method is the same as the first section. When the third section is excavated, the arch frame at the corresponding position of the first section will be firmly supported with DN89 steel pipes. When the fourth section is excavated, the temporary support between the first and third sections will be extended to the bottom of the fourth section. When the fourth and fifth sections are excavated, temporary transverse supports will be added at the bottom. The tunnel cross-section is divided into upper step, middle step and lower step from top to bottom; The upper step is composed of a C-shaped cross section at the top and a D-shaped cross section at the bottom. The C-shaped cross section is divided into three parts, namely, part ②, part ① and part ③ from left to right. The D-shaped cross section is divided into two parts, namely, part ⑤ and part ④. The middle steps are divided into two parts, from left to right: part ⑦ and part ⑥. The steps are divided into two parts, from left to right: part 9 and part 8.

2. The rapid construction method for blasting hole layout structure in water conveyance tunnels according to claim 1, characterized in that, The upper step is provided with slotting holes, auxiliary holes, bottom holes and peripheral holes on each part; The middle and lower steps are provided with intermediate eyes, auxiliary eyes, bottom eyes and peripheral eyes; By setting the location of the slot or the middle slot, then arranging the peripheral slots and the bottom slots, and finally arranging the auxiliary slots according to the cross-sectional size.

3. The rapid construction method for blasting hole layout structure in water conveyance tunnels according to claim 2, characterized in that, The cut holes are located slightly below the center of the excavation face; the peripheral holes are located on the outline of the tunneling section and meet the requirements of smooth blasting, with an outward inclination of 0.03-0.

05.

4. The rapid construction method for blasting hole layout structure in water conveyance tunnels according to claim 2, characterized in that, The slotting holes are wedge-shaped, the auxiliary holes are evenly distributed in a plum blossom pattern, and the peripheral holes are light-burst holes.

5. A rapid construction method for blasting hole layout structure in a water conveyance tunnel according to claim 2, characterized in that, Both the slotted eye and the auxiliary eye are loaded with uncoupled continuous explosives, while the peripheral eye is loaded with uncoupled intermittent explosives; and the peripheral eye is loaded with explosives at intervals by small explosive rolls tied to bamboo strips.

6. A rapid construction method for blasting hole layout structure in a water conveyance tunnel according to claim 2, characterized in that, The upper step adopts a two-stage wedge-shaped groove, with auxiliary eye holes 0.5m deep and 0.7m apart; the peripheral eye holes are light-burst holes with a hole spacing of 0.45m and a hole depth of 0.5m; The hole arrangement for the middle and lower steps is as follows: row spacing is 0.8m, auxiliary hole spacing is 0.7m, and peripheral hole spacing is 0.45m.

7. A rapid construction method for blasting hole layout structure in a water conveyance tunnel according to claim 1, characterized in that, In the construction steps of the climbing section excavation and support, The excavation construction steps include: excavation using the full-section method; excavation using a hand-held pneumatic drill and blasting, with smooth blasting along the designed outline; and on-site treatment. The support construction steps include: construction preparation → steel support → anchor bolt construction → hanging steel mesh and connecting bars → mortar anchor bolt and advanced small guide pipe construction → shotcrete construction to the design thickness → next cycle of excavation and support. The bottom excavation steps of the climbing section include: the unexcavated part at the bottom of the climbing section is excavated simultaneously with the excavation of the dismantling holes ⑥, ⑦ and ⑧ and ⑨, and steel arch frames of the same model as the upper arch frame are installed, steel mesh is laid, longitudinal connecting bars are welded, system anchor bolts and locking foot anchor bolts are installed in sections of each arch frame, and sprayed concrete support is carried out in a timely manner. The secondary lining process for the climbing section includes: the secondary lining of the transition section is poured using a secondary lining trolley for the transport tunnel, and the top cavity is backfilled with lightweight concrete.

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