Slope pipe shed construction method under complex geological conditions

Abstract

The application provides a slope pipe shed construction method under complex geological conditions, and belongs to the technical field of tunnel construction. S1, upper arch construction, the excavation height of the step is determined according to the height of the drilling machine, a pipe shed drilling machine construction platform is formed, an arch top support is installed at the arch top, and three-dimensional simulation of the tunnel, the arch and the guide wall is carried out based on the parameters of the tunnel by using software; S2, pipe shed installation, the installation hole position of the pipe shed is drilled in the hole in advance by using the drilling machine according to the design scheme, the pipe shed is drilled, and then large pipe shed steel pipe installation is carried out; S3, grouting, after the pipe shed installation is completed, grouting is carried out by using a grouting machine, and the grouting is sequentially carried out from low hole position to high hole position; S4, lower structure installation, the soil body of the portal is excavated, and the anchor rod is fixed at the position of the upper guide wall foundation. The problems of the risk of rockfall during construction in the traditional method, the need to set up a working surface for drilling and the long construction time are solved.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, and more specifically, relates to a method for constructing a pipe roof on a slope under complex geological conditions. Background Technology

[0002] Pumped storage power station projects are a relatively new type of new energy water conservancy and hydropower project that has emerged in recent years. Due to the nature of the working principle of the power station, the project site is located on a mountain with a considerable elevation difference and is closely linked to the tunnel (tunnel) excavation project. Tunnel (tunnel) construction often faces problems such as poor geological conditions, easy collapse during the excavation process, and abundant groundwater. Therefore, relevant technologies are needed to provide necessary support for the tunnel (tunnel) structure to prevent collapse and landslides. The current conventional method is to erect pipe sheds for support in the excavated part at the tunnel entrance.

[0003] Conventional methods have the following problems: ① Before installing the steel arch frame of the pipe shed, the entire outline must be excavated on the slope. When the engineering geology is poor, there is a risk of falling rocks and injuries during the excavation process; ② When drilling holes in the arched part of the pipe shed, it is usually necessary to erect a steel frame or fill a platform to provide a working surface for the drilling machine. This process takes a long time and requires a large amount of materials. Summary of the Invention

[0004] This invention provides a method for constructing pipe roofs on slopes under complex geological conditions, which solves the problems of falling rocks during construction and the need to set up working faces for drilling, resulting in long construction time in traditional methods.

[0005] In view of the above problems, the technical solution proposed by the present invention is:

[0006] This invention provides a method for constructing pipe roofs on slopes under complex geological conditions, comprising the following steps:

[0007] S1, upper arch frame construction: the excavation height of the steps is determined according to the height of the drilling rig itself, forming a pipe roof drilling rig construction platform. The tunnel centerline and outer arch elevation are marked on the slope surface according to the control piles and elevation control points of the line centerline. Arch supports are installed at the arch top. Based on the tunnel parameters, software is used to establish a three-dimensional model of the tunnel, arch frame and guide wall, and a three-dimensional simulation is performed. The simulation results are used to optimize the design scheme of the upper structure.

[0008] S2, Pipe Roof Installation: According to the design plan, drilling rigs are used to pre-drill the installation holes for the pipe roof inside the tunnel, and holes are drilled in the pipe roof. Grouting holes with a diameter of 10mm are drilled in the pipe roof wall. The pipe roof is installed by jacking and lengthened section by section. The steel pipes are connected by threaded connections, and then the large pipe roof steel pipes are installed.

[0009] S3. Grouting: After the pipe roof is installed, grouting is carried out using a grouting machine. PO42.5 ordinary Portland cement is selected, and cement grout with a water-cement ratio of 1:1 is used. Grouting is carried out sequentially from low hole position to high hole position. Single liquid grouting is performed on the steel pipe. When the pressure reaches the design final grouting pressure and stabilizes for 10-15 minutes, and the grouting volume reaches more than 80% of the design grouting volume, the grouting of the hole is ended.

[0010] S4, Substructure Installation: Excavate the soil at the entrance of the tunnel to the bottom of the access tunnel. Use anchor bolts to fix the upper guide wall foundation. Install I-beams at the excavation site. After fixing, erect formwork around the site and perform concrete grouting. After the lower guide wall is installed, proceed with the construction of the guide wall sidewall section and guide wall foundation to complete the installation of the substructure.

[0011] As a preferred technical solution of the present invention, the pipe roof drilling rig construction platform in step S1 adopts a modular design, including several drilling rig construction platform modules. Each drilling rig construction platform module includes two support frames, diagonal braces, and connecting columns. The support frames are U-shaped, and both the upper and lower ends of the sides of the support frames are hollow. The diagonal braces are arranged between the two support frames, and the two diagonal braces form a group with an X-shaped design. Fixing bolts are provided between the diagonal braces and the support frames. The connecting columns are inserted into the upper end of the support frames, and mounting bolts are provided between the connecting columns and the upper end of the support frames. A pin passes through the upper end near the connecting column, and the platform plate is screwed onto the top of the drilling rig construction platform at the uppermost end.

[0012] As a preferred embodiment of the present invention, the arch support in step S1 includes embedded blocks, support rods, arch rods, and angle irons. Based on the installation position design of the arch support in step S1, several embedded blocks are pre-embedded. Two support rods are welded to each embedded block. The shape of the arch rods is adapted to the arch. The arch rods pass through the support rods and are bolted to the support rods. The angle irons are placed between the support rods and the arch rods and are fixed with bolts. The connecting edge of the angle irons to the arch rods is adapted to the shape of the arch rods.

[0013] As a preferred embodiment of the present invention, the detailed steps of the three-dimensional simulation in step S1 are as follows:

[0014] S11. Use a total station to obtain the dimensions and shape of the tunnel and record other relevant parameters of the tunnel;

[0015] S12. Using 3D software combined with measured tunnel parameters, a 3D model of the tunnel and arch frame is established, including the curvature of the hyperboloid and the structure of the arch frame. The parameters of the tunnel are defined, and the parameters of the arch frame and guide wall are set.

[0016] S13. According to the needs of structural analysis, stress points are arranged in key parts of the model, loads are applied to the model, and analysis is performed using finite element software.

[0017] S14. Based on the analysis results, optimize the structure of the arch frame and guide wall, and simulate again until the design scheme is reasonable.

[0018] As a preferred technical solution of the present invention, in step S1, four 18-beam steel frames are installed inside the guide wall. Each steel frame is divided into seven units. Connecting plates are welded to both ends of each steel frame section. The units of the I-beams are welded together through the connecting plates and connected with bolts. After the steel frames are assembled, they are test-assembled on the cement ground. The steel frames are placed on the stable bedrock. When the arch foot is excavated to an excessive depth, steel plates or concrete pads are added. After the I-beams are erected, the arch foot foundation is constructed. The arch foot is 1m wide and 1.5m high, with a 0.8m high sloping opening at the bottom. Ten C25 anchor rods are installed in the foundation. The anchor rods are 6m long and have a rock penetration depth of 4m. The anchor rods are connected to the I-beams by single-sided lap welding. C30 concrete guide wall foundation is poured. At the same time as the arch foot foundation is poured, the guide pipe is buried. The guide pipe is welded to the I-beams. When installing the guide pipe, it is necessary to press it against the end formwork and take measures to firmly fix it on the end formwork. After the guide pipe is installed, the formwork is installed. The formwork must be firmly and reliably installed, and a release agent must be applied to the surface of the formwork in contact with the concrete. Following the formwork installation, concrete is poured. C25 concrete is used for the guide wall. Strict quality control of materials is required during construction. Pour and compact the concrete manually and mechanically. The pouring sequence is symmetrical from both sides of the arch foot to the arch crown. After the concrete is poured, it must be cured promptly for at least 7 days. Non-load-bearing formwork (outer formwork) and end formwork can be removed when the concrete strength reaches 70% of the design strength. Inner formwork and supports can be removed when the strength reaches 100% of the design strength.

[0019] As a preferred technical solution of the present invention, the use of the drilling machine in step S2 is specifically as follows: when drilling the surface of an object, a large-diameter drill bit is used, and the cutting part is grooved or spiral-shaped. The cutting teeth are block teeth or spoon-shaped teeth, the tooth spacing is selected as 10-25mm, and the number of teeth per revolution is designed as 2-6. The diameter of the drill bit for the middle layer gradually decreases with the increase of the number of layers. The cutting teeth adopt a mixed design of pointed teeth and block teeth, the tooth spacing is selected as 5-15mm, and the number of teeth per revolution is designed as 4-10. The diameter of the drill bit for the bottom layer is further reduced to meet the hardness of the bottom layer, and the cutting part uses a fine spiral shape. The cutting teeth are designed as pointed teeth, the tooth spacing is selected as 2-10mm, and the number of teeth per revolution is designed as 8-22.

[0020] The installation of the steel pipes for the pipe shed is as follows: First, an excavator is used to lift the tip section of the steel pipe, and manual alignment and jacking are performed. The tip section of the steel pipe is then connected to the second standard section of the steel pipe using threaded steel pipe threads. The second standard section of the steel pipe is lifted by an excavator to the same height as the tip section of the steel pipe, and then manually threaded connection is performed. This operation is repeated to connect the third section and the top section of the steel pipe and jack the pipe. This process is repeated to complete the extension and installation of the entire large pipe shed steel pipe.

[0021] As a preferred embodiment of the present invention, the construction of the anchor bolts within the arch foot foundation specifically involves:

[0022] According to the design, boreholes are drilled inside the opening, with the anchor bolt hole axis perpendicular to the excavation face. The holes are washed with high-pressure air and water, and high-pressure air is used to blow away the water and rock powder inside the holes. The opening is temporarily sealed to form a sealing zone. The construction method of inserting the bolts first and then grouting is adopted. The grouting pipe should be inserted into the bottom of the hole, and then pulled out 50-100mm to start grouting. The grouting pipe is slowly and evenly pulled out as the grout is injected, so that the hole is filled with grout. Grouting can be stopped when grout comes out of the exhaust pipe.

[0023] As a preferred embodiment of the present invention, an anchor rod, an exhaust pipe, and a grouting pipe are installed in the hole sealing area. The anchor rod is made of HRB400 grade steel bar with a diameter of 20mm, and the anchor rod is 2500mm long with 100mm exposed. The exhaust pipe is located between the grouting pipe and the anchor rod, and the end of the anchor rod is equipped with a locking foot. The front end of the locking foot anchor rod is pre-bent into an L-shape and welded to the steel arch frame. Each steel frame is connected to at least 3-5 anchor rods and is equipped with locking foot anchor rods. The locking foot anchor rods are installed at a downward tilt angle of 40°.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention constructs a pipe roof structure by dividing it into upper and lower parts. The upper part of the pipe roof serves as a protective barrier and delays the excavation of the soil at the opening, reducing material usage, accelerating the construction cycle, and lowering construction difficulty and safety risks. Before excavating the foundation, the arched part of the upper pipe roof is constructed, and anchor rods are inserted at the location of the upper foundation to fix the entire upper pipe roof. Finally, the lower part of the pipe roof is excavated. This process prioritizes the completion of the upper part of the pipe roof, which not only reinforces the upper part of the opening and reduces safety hazards but also improves project efficiency.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0027] Figure 1This is a schematic flowchart of a slope pipe roof construction method under complex geological conditions disclosed in this invention;

[0028] Figure 2 This is a schematic diagram of the assembly of a drilling rig construction platform module for a slope pipe roof construction method under complex geological conditions disclosed in this invention.

[0029] Figure 3 This is a schematic diagram of the structure of a single drilling rig construction platform module of a slope pipe roof construction method under complex geological conditions disclosed in this invention;

[0030] Figure 4 This is a schematic diagram of the arch support structure of a slope pipe roof construction method under complex geological conditions disclosed in this invention;

[0031] Figure 5 This is a schematic diagram of the anchor structure for a slope pipe roof construction method under complex geological conditions disclosed in this invention;

[0032] Figure 6 This is a schematic diagram of the pipe roof structure construction method for slope pipe roof construction under complex geological conditions disclosed in this invention;

[0033] Figure 7 This is a schematic diagram of the construction of the lower structure of a slope pipe roof construction method under complex geological conditions disclosed in this invention;

[0034] Explanation of reference numerals in the attached drawings: 100, Drilling rig construction platform module; 101, Support frame; 102, Diagonal brace; 103, Fixing bolt; 104, Connecting column; 105, Pin; 106, Mounting bolt; 200, Arch support; 201, Embedded block; 202, Support rod; 203, Arch rod; 204, Angle iron; 300, Anchor bolt; 400, Exhaust pipe; 500, Grouting pipe; 600, Tunnel entrance sealing area. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] Example 1

[0041] See attached document Figure 1-7 As shown, the present invention provides a technical solution: a method for constructing pipe roofs on slopes under complex geological conditions, comprising the following steps:

[0042] S1, Upper arch frame construction: Determine the excavation height of the steps based on the height of the drilling rig itself to form a pipe roof drilling rig construction platform. Mark the tunnel centerline and outer arch elevation on the slope surface based on the line centerline control piles and elevation control points. Install arch support 200 at the arch top. Based on the tunnel parameters, use software to establish a three-dimensional model of the tunnel, arch frame and guide wall. Draw the outer arch arc on the slope surface based on the outline of the tunnel excavation as the basis for the guide wall formwork. Control the height of the inner and outer formwork of the guide wall according to the mileage of the guide wall and reserve the corresponding settlement amount. Simulate the parameters of the upper part and optimize the design scheme of the upper structure using the simulation results.

[0043] S2, Pipe Roof Installation: According to the design plan, drilling rigs are used to pre-drill installation holes for the pipe roof inside the tunnel. The height of the drilling platform is determined based on the adjustable range of the drilling rig and the drilling sequence. After drilling, the holes must be cleared immediately and the pipes lowered to prevent internal blockage due to hole collapse, which could hinder installation. Long pipe roofs use seamless steel pipes with a diameter of 108mm and a wall thickness of 6mm. Grouting holes with a diameter of 10mm are drilled on the pipe wall, arranged in a staggered pattern with a longitudinal and transverse spacing of 30cm. The tail section is a 100cm un-drilled grout-stopping section. The number of joints in the same cross-section of the steel pipe must not exceed 50% of the total number of pipes. Before installation, high-pressure air is used to clean and sweep the holes, removing any floating debris and ensuring that the hole diameter (not less than 120cm) and depth meet the requirements to prevent blockage. The pipe roof is installed using a jacking method, extending section by section. The pipes are connected by threaded connections, with each thread being 15cm long and the threaded steel pipe being 30cm long. The steel pipe joints are staggered according to odd and even numbers, and the number of joints in the same longitudinal section does not exceed 50%. The joints of adjacent steel pipes must be staggered by at least 1m. For the installation of the large pipe shed steel pipes, firstly, an excavator is used to lift the tip section of the steel pipe, and manual alignment and pushing are performed. If manual pushing of the steel pipe into the hole is not possible, temporary support points are erected for the exposed part of the steel pipe using gantry frames. The tip section of the steel pipe is connected to the second standard section of the steel pipe using threaded steel pipe. The second standard section of the steel pipe is lifted by an excavator to the same height as the tip section of the steel pipe, and then the threads are manually connected. After the threads are connected, temporary support points are erected using gantry frames. When the second standard section of the steel pipe is pushed in for 2-3m, this operation is repeated to connect the third section and the top section of the steel pipe and push the pipe. This process is repeated to complete the lengthening and installation of the entire large pipe shed steel pipe.

[0044] S3. After the pipe roof installation is completed, drill holes in the opening according to the design. The hole axis of anchor bolt 300 is perpendicular to the excavation face. Anchor bolt 300 is adjusted according to the surrounding rock fissures to ensure penetration through the fissures. The hole is washed with high-pressure air and water, and water and rock powder in the hole are blown away with high-pressure air. The hole opening is temporarily sealed to form a 600mm sealing zone. Grouting is carried out using a grouting machine. PO42.5 ordinary Portland cement is selected, and the grout uses a cement grout with a water-cement ratio of 1:1. If there is a relatively developed groundwater, 5% water glass can be added to the cement grout volume. The water glass concentration is 35 Baume degrees. The grouting parameters should be qualified through on-site testing. The construction method of inserting the rod first and then grouting is adopted. The grouting pipe 500 should be inserted into the bottom of the hole and then pulled out 50-100mm to start grouting. Single-liquid grouting is performed on the steel pipe. The grouting pipe 500 is slowly injected with the grout. Pull out the grout at a uniform speed to fill the hole with grout. When inserting the rod first and then grouting, the grouting pipe 500, the vent pipe 400, and the anchor rod 300 should be installed simultaneously, and a grout stopper should be installed at the hole opening. The inner end of the vent pipe 400, which extends to the bottom of the hole, should be 500-100mm from the bottom of the hole. The length of the grouting pipe 500, located at the hole opening, inserted into the anchor rod 300 hole should not be less than 200mm. Grouting can be stopped when grout comes out of the vent pipe 400. For the downward-sloping anchor rod 300, the grouting pipe 500 should be inserted to 5cm from the bottom of the hole. Grouting should continue until grout returns to the hole opening. The initial pressure is 0.5-1.0MPa, and the final pressure is 2.0MPa. When the pressure reaches the designed final grouting pressure and stabilizes for 10-15 minutes, and the grouting volume reaches more than 80% of the designed grouting volume, the grouting of the hole should be stopped. Adjust the parameters according to the actual situation, and slowly pull out the grouting pipe 500 to complete the grouting.

[0045] S4. Substructure Installation: Excavate the soil at the opening to the bottom of the access tunnel. Secure the upper guide wall foundation with 300mm anchor rods, thus fixing the entire upper structure at the opening. Install I-beams at the excavation site, connecting them to pre-reserved I-beam base plates at the bottom of the upper foundation. After fixing, erect formwork around the perimeter and perform concrete grouting. After the lower guide wall is installed, proceed with the construction of the guide wall sidewalls and foundation. The guide wall concrete foundation should be placed on the original soil to ensure the stability and reliability of the pipe roof guide wall. The technical requirements for C30 concrete pouring must be met; raw materials and concrete must comply with the project department's laboratory mix proportions and design requirements. Install the sidewall steel arch frame and bolt it to the pipe roof steel pipes, completing the substructure installation. 。

[0046] The embodiments of the present invention are also implemented through the following technical solutions.

[0047] In an embodiment of the present invention, the pipe roof drilling rig construction platform in step S1 adopts a modular design, including several drilling rig construction platform modules 100. Each drilling rig construction platform module 100 includes two support frames 101, diagonal braces 102, and connecting columns 104. The support frames 101 have a U-shaped design, and both the upper and lower ends of the sides of the support frames 101 are hollow. The diagonal braces 102 are arranged between the two support frames 101, and the two diagonal braces 102 form a group with an X-shaped design. Fixing bolts 103 are provided between the diagonal braces 102 and the support frames 101. The two support frames 101 are connected together through the diagonal braces 102 and fixed with fixing bolts 103 to form a single layer of pipe roof drilling rig construction platform. The platform consists of several layers of pipe roof drilling rig construction platforms, installed according to the drilling rig requirements. Connecting columns 104 are inserted into the upper end of support frames 101. Mounting bolts 106 are provided between the connecting columns 104 and the upper end of support frames 101. The connecting columns 104 are installed on the support frames 101 using the mounting bolts 106. A pin 105 passes through the upper end near the connecting column 104. During assembly, adjacent support frames 101 are connected by connecting columns 104, and the pin 105 passes through the connection point to achieve assembly. Finally, a platform plate is screwed onto the top of the drilling rig construction platform at the top, and the drilling rig is placed on it. Different sizes of support frames 101 and diagonal braces 102 are adjusted and replaced according to different drilling rigs.

[0048] In an embodiment of the present invention, the arch support 200 in step S1 includes a pre-embedded block 201, a support rod 202, an arch rod 203, and an angle iron 204. Based on the installation position design of the arch support 200 in step S1, several pre-embedded blocks 201 are pre-embedded. Two support rods 202 are welded to each pre-embedded block 201. The shape of the arch rod 203 is adapted to the arch. The arch rod 203 passes through the support rod 202 and is bolted to the support rod 202. The angle iron 204 is placed between the support rod 202 and the arch rod 203 and is fixed with bolts. The connecting edge of the angle iron 204 and the arch rod 203 is adapted to the shape of the arch rod 203.

[0049] In an embodiment of the present invention, the detailed steps of the three-dimensional simulation in step S1 are as follows:

[0050] S11. Use a total station to obtain the dimensions and shape of the tunnel, and record other relevant parameters of the tunnel, including its length, width, height, curvature, and slope.

[0051] S12. Using 3D software combined with measured tunnel parameters, a 3D model of the tunnel and arch frame is established, including the curvature of the hyperboloid and the structure of the arch frame. The parameters of the tunnel are defined, and the parameters of the arch frame and guide wall are set, such as cross-sectional dimensions, material type, elastic modulus, etc.

[0052] S13. According to the needs of structural analysis, stress points are arranged in key parts of the model, loads are applied to the model, and analysis is performed using finite element software.

[0053] S14. Based on the analysis results, optimize the structure of the arch frame and guide wall, and simulate again until the design scheme is reasonable.

[0054] In an embodiment of the present invention, to ensure the rigidity of the pipe shed construction in step S1, four 18-beam steel frames are installed inside the guide wall. The radius of the I-beams is 5.95m, and the spacing is 0.67m. Each frame is divided into seven units. The steel frame must ensure that the curvature and dimensions of each section meet the design requirements. Connecting plates are welded to both ends of each section of the steel frame. The units of the I-beams are welded together through the connecting plates and connected with bolts. The connecting plates should fit tightly. After processing, a trial assembly inspection is performed. Each end of each frame requires a total of 6 sets of bolts and nuts. The steel frame should be installed strictly according to the design centerline and horizontal position. The lower end of the steel frame is placed on a stable stratum, and the height of the arch foot is lower than the upper excavation bottom line. For the first 15-20cm section, the steel frame should be completely covered by concrete during pouring. The protective layer thickness should not be less than 40mm. After assembly, the steel frame should be test-assembled on a concrete surface. The allowable deviation around the perimeter of the steel frame assembly is ±3cm, and the planar warping should be less than 2cm. The steel frame should be placed on stable bedrock. If the arch foot excavation is too deep, steel plates or concrete blocks should be added. When installing the I-beams, the distance from the bottom of the I-beam to the top surface of the inner formwork should reach 21cm (i.e., the thickness of the concrete protective layer at the bottom of the I-beam). After the I-beam frame is erected, the arch foot foundation construction should be carried out. The arch foot foundation will support the arch crown guide wall after the guide wall sidewall is excavated. The arch foot is 1m wide and 1.5m high, with a 0.8m high sloping opening at the bottom to facilitate the compaction of the guide wall sidewall after excavation. Ten C25 300 anchor rods, each 6m long and 4m deep into the rock, are installed within the foundation. The anchor rods are connected to the I-beams using single-sided lap welding. C30 concrete guide wall foundation is poured. Simultaneously with the arch foot foundation pouring, the guide pipe is installed. To prevent displacement during concrete pouring, the guide pipe is welded to the I-beam frame. To prevent mortar from entering and clogging the guide pipe during concrete pouring, the guide pipe must be firmly secured to the end formwork during installation. After the guide pipe is installed, the formwork is installed. The formwork must be installed firmly and reliably. The contact surface between the formwork and the concrete must be coated with a release agent. After the formwork is installed, the concrete is poured. C25 concrete is used for the guide wall. The quality of the materials must be strictly controlled during the construction process. The pouring and compaction are done manually and mechanically. The pouring sequence is symmetrical from both sides of the arch foot to the arch top. After the concrete is poured, it must be cured in time. The curing period shall not be less than 7 days. The non-load-bearing formwork (outer formwork) and end formwork can be removed after the concrete strength reaches 70% of the design strength. The inner formwork and supports can be removed after the strength reaches 100% of the design strength.

[0055] In an embodiment of the present invention, the use of the drilling machine in step S2 specifically involves using a large-diameter drill bit when drilling into the surface of an object. The cutting part uses a groove or spiral shape to quickly penetrate the surface layer. The cutting teeth are block teeth or spoon-shaped teeth, with a tooth spacing of 10-25mm and a tooth count of 2-6 per revolution. A larger tooth spacing helps reduce material consumption and lower costs, covering a larger area and increasing penetration speed. The drill bit diameter for the intermediate layers gradually decreases with the increase of the number of layers to accommodate objects of varying hardness. The cutting teeth employ a hybrid design of pointed and block teeth, with a tooth spacing of 5-15mm. The drill bit has 4-10 teeth per revolution, and the close arrangement helps to improve cutting efficiency while ensuring sufficient chip removal space to accommodate the hardness of the intermediate layer. The bottom layer drill bit has a smaller diameter to accommodate the hardness of the bottom layer for precise drilling. The cutting part uses a fine spiral shape, and the cutting teeth are sharp. The tooth spacing is 2-10mm, and the number of teeth per revolution is 8-22. The close arrangement ensures that each tooth can effectively participate in cutting. This drill bit solution is suitable for soft surface and hard bottom layer. Conversely, when the surface layer is hard and the bottom layer is soft, the bottom layer drill bit and the surface layer drill bit solution mentioned above can be replaced.

[0056] In an embodiment of the present invention, an anchor rod 300, an exhaust pipe 400, and a grouting pipe 500 are installed in the opening sealing area 600. The anchor rod 300 is made of HRB400 grade steel bar with a diameter of 20mm. The anchor rod 300 is 2500mm long and 100mm is exposed. The exhaust pipe 400 is located between the grouting pipe 500 and the anchor rod 300. The end of the anchor rod 300 is equipped with a locking foot. The front end of the locking foot anchor rod 300 is pre-bent into an L-shape and welded to the steel arch frame. The steel frame and the locking foot anchor rod 300 must be welded firmly to form a whole. Each steel frame is connected to at least 3-5 anchor rods 300 and is equipped with locking foot anchor rods 300. The locking foot anchor rod 300 is installed at a downward tilt angle of 40°.

[0057] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0058] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to a specific order or hierarchy.

[0059] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, with each claim representing a separate preferred embodiment of the invention.

Claims

1. A method for constructing pipe roofs on slopes under complex geological conditions, characterized in that, Includes the following steps: S1, upper arch frame construction: the excavation height of the steps is determined according to the height of the drilling rig itself, forming a pipe roof drilling rig construction platform. The tunnel centerline and outer arch elevation are marked on the slope surface according to the control piles and elevation control points of the line centerline. An arch support (200) is installed at the arch top. Based on the tunnel parameters, a three-dimensional model of the tunnel, arch frame and guide wall is established using software. A three-dimensional simulation is performed, and the simulation results are used to optimize the design scheme of the upper structure. S2, Pipe Roof Installation: According to the design plan, drilling rigs are used to pre-drill the installation holes for the pipe roof inside the tunnel, and holes are drilled in the pipe roof. Grouting holes with a diameter of 10mm are drilled in the pipe roof wall. The pipe roof is installed by jacking and lengthened section by section. The steel pipes are connected by threaded connections, and then the large pipe roof steel pipes are installed. S3. Grouting: After the pipe roof is installed, grouting is carried out using a grouting machine. PO42.5 ordinary Portland cement is selected, and cement grout with a water-cement ratio of 1:1 is used. Grouting is carried out sequentially from low hole position to high hole position. Single liquid grouting is performed on the steel pipe. When the pressure reaches the design final grouting pressure and stabilizes for 10-15 minutes, and the grouting volume reaches more than 80% of the design grouting volume, grouting is stopped. S4, Substructure Installation: Excavate the soil at the entrance of the tunnel to the bottom of the entrance to the factory. Use anchor rods (300) to fix the upper guide wall foundation. Set I-beams at the excavation site. After fixing, set up formwork around the site and perform concrete grouting. After the lower guide wall is installed, carry out the construction of the guide wall side wall section and guide wall foundation to complete the installation of the substructure.

2. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 1, characterized in that, In step S1, the pipe roof drilling rig construction platform adopts a modular design, including several drilling rig construction platform modules (100). Each drilling rig construction platform module (100) includes two support frames (101), diagonal braces (102), and connecting columns (104). The support frame (101) has a U-shaped design, and both the upper and lower ends of the side of the support frame (101) are hollow. The diagonal braces (102) are located between the two support frames (101). 02) is a group, in an X-shaped design. The diagonal brace (102) and the support frame (101) are provided with fixing bolts (103). The connecting column (104) is inserted into the upper end of the support frame (101). The connecting column (104) and the upper end of the support frame (101) are provided with mounting bolts (106). A pin (105) passes through the upper end near the connecting column (104). The platform plate is mounted on the top screw of the drilling rig construction platform at the uppermost end.

3. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 2, characterized in that, The arch support (200) in step S1 includes a pre-embedded block (201), a support rod (202), an arch rod (203), and an angle iron (204). Based on the installation position design of the arch support (200) in step S1, several pre-embedded blocks (201) are pre-embedded. Two support rods (202) are welded to each pre-embedded block (201). The shape of the arch rod (203) is adapted to the arch. The arch rod (203) passes through the support rod (202) and is bolted to the support rod (202). The angle iron (204) is set between the support rod (202) and the arch rod (203) and is fixed with bolts. The connecting edge of the angle iron (204) and the arch rod (203) is adapted to the shape of the arch rod (203).

4. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 3, characterized in that, The detailed steps of the three-dimensional simulation in step S1 are as follows: S11, Use a total station to obtain the dimensions and shape of the tunnel; S12. Using 3D software combined with measured tunnel parameters, a 3D model of the tunnel and arch frame is established, including the curvature of the hyperboloid and the structure of the arch frame. The parameters of the tunnel are defined, and the parameters of the arch frame and guide wall are set. S13. According to the needs of structural analysis, stress points are arranged in key parts of the model, loads are applied to the model, and analysis is performed using finite element software. S14. Based on the analysis results, optimize the structure of the arch frame and guide wall, and simulate again until the design scheme is reasonable.

5. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 4, characterized in that, In step S1, four 18-mesh I-beam frames are installed inside the guide wall. Each frame is divided into seven units, and connecting plates are welded to both ends of each section. The I-beam units are welded together through the connecting plates and connected with bolts. After the steel frames are assembled, they are test-assembled on a cement floor. The steel frames are then placed on stable bedrock. When the arch foot excavation is too deep, steel plates or concrete pads are added. After the I-beam frames are erected, the arch foot foundation is constructed. The arch foot is 1m wide and 1.5m high, with a 0.8m high sloping opening at the bottom. Ten C25 anchor rods (300) are installed inside the foundation. The anchor rods (300) are 6m long and have a rock penetration depth of 4m. The anchor rods (300) are connected to the I-beams using single-sided lap welding. The C30 concrete guide wall foundation is poured. At the same time as the arch foot foundation is poured, the guide pipe is buried. The guide pipe is welded to the I-beam frame. When installing the guide pipe, it must be pressed tightly against the end formwork and measures must be taken to firmly fix it to the end formwork. After the guide pipe is installed, the formwork is installed. The formwork installation must be firm and reliable. The contact surface between the formwork and the concrete must be coated with a release agent. After the formwork is installed, the concrete is poured. C25 concrete is used for the guide wall. The quality of the materials must be strictly controlled during the construction process. The pouring and compaction are carried out manually and mechanically. The pouring sequence is to pour symmetrically from both sides of the arch foot until the arch top. After the concrete is poured, it must be cured in time. The curing period shall not be less than 7 days. The non-load-bearing formwork (outer formwork) and end formwork can be removed after the concrete strength reaches 70% of the design strength. The inner formwork and support can be removed after the strength reaches 100% of the design strength.

6. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 1, characterized in that, In step S2, the drilling machine is used specifically as follows: when drilling holes in the surface of an object, a large-diameter drill bit is used, and the cutting part is grooved or spiral-shaped. The cutting teeth are block teeth or spoon-shaped teeth, with a tooth spacing of 10-25mm and a tooth count of 2-6 per revolution. The drill bit diameter of the middle layer gradually decreases with the increase of the number of layers. The cutting teeth adopt a mixed design of pointed teeth and block teeth, with a tooth spacing of 5-15mm and a tooth count of 4-10 per revolution. The drill bit of the bottom layer has a further reduced diameter to meet the hardness of the bottom layer, and the cutting part uses a fine spiral shape. The cutting teeth are pointed teeth, with a tooth spacing of 2-10mm and a tooth count of 8-22 per revolution. The installation of the steel pipes for the pipe shed is as follows: First, an excavator is used to lift the tip section of the steel pipe, and manual alignment and jacking are performed. The tip section of the steel pipe is then connected to the second standard section of the steel pipe using threaded steel pipe threads. The second standard section of the steel pipe is lifted by an excavator to the same height as the tip section of the steel pipe, and then manually threaded connection is performed. This operation is repeated to connect the third section and the top section of the steel pipe and jack the pipe. This process is repeated to complete the extension and installation of the entire large pipe shed steel pipe.

7. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 5, characterized in that, The specific construction of the anchor bolts (300) within the arch foot foundation is as follows: According to the design, boreholes are drilled inside the opening. The direction of the hole axis of the anchor rod (300) is perpendicular to the excavation face. The hole is washed with high-pressure air and water, and the water and rock powder inside the hole are blown away with high-pressure air. The opening is temporarily sealed to form the opening sealing area (600). The construction is carried out by first inserting the rod and then grouting. The grouting pipe (500) should be inserted into the bottom of the hole and then pulled out 50-100mm to start grouting. The grouting pipe (500) is slowly and evenly pulled out as the grout is injected, so that the hole is filled with grout. Grouting can be stopped when the vent pipe (400) discharges grout.

8. The method for constructing a pipe roof on a slope under complex geological conditions according to claim 7, characterized in that, Anchor rods (300), vent pipes (400), and grouting pipes (500) are installed in the sealing area (600) of the opening. The anchor rods (300) are made of HRB400 grade steel bars with a diameter of 20mm. The anchor rods (300) are 2500mm long and 100mm are exposed. The vent pipes (400) are located between the grouting pipes (500) and the anchor rods (300). The ends of the anchor rods (300) are equipped with locking feet. The front end of the locking foot anchor rods (300) is pre-bent into an L shape and welded to the steel arch frame. Each steel frame is connected to at least 3-5 anchor rods (300) and is equipped with locking foot anchor rods (300). The locking foot anchor rods (300) are installed at an angle of 40° downward tilt.

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