A construction method and structural system for a crane beam structure on the rock wall of an underground powerhouse

Abstract

This invention discloses a construction method and structural system for a crane beam structure on a rock wall in an underground powerhouse. The method involves excavating the rock wall and constructing an upper row of pre-embedded tie rods, prestressed anchor rods, pre-embedded steel sections, and a lower row of pre-embedded tie rods. The upper row of pre-embedded tie rods and prestressed anchor rods are located on the upper vertical surface of the rock wall, the pre-embedded steel sections are located on the inclined surface of the rock wall, and the lower row of pre-embedded tie rods are located on the lower vertical surface of the rock wall. The bottom formwork and side formwork are constructed, with the bottom formwork located above and fixed to the lower row of pre-embedded tie rods. The side formwork is vertically positioned and fixed by the upper and lower row of pre-embedded tie rods. The prestressed anchor rods are connected to the side formwork via overlapping anchor rods. Channel steel perpendicular to the direction of the steel sections is placed on the bottom formwork. A reinforcing cage is placed within the space formed by the bottom and side formworks, and reinforcing bars are reserved. The rock wall beam is poured and cured. After the rock wall beam has cured, the side formwork, bottom formwork, and other auxiliary installation frames are removed. The reserved reinforcing bars are connected to the reinforcing bars of the structural columns, and the structural columns are poured.

Description

Technical Field

[0001] This invention relates to the field of underground cavern construction technology, specifically to a construction method and structural system for a crane beam on the rock wall of an underground powerhouse in a hydropower station. Background Technology

[0002] Rock wall crane beams are a structural type in which reinforced concrete and rock mass share the load. They are characterized by their simple structure, reduced rock excavation for power plant construction, and faster commissioning after excavation. The principle involves using the tensile strength of anchor bolts and the frictional force of the rock mass supporting the underground power plant's sidewalls to anchor the reinforced concrete crane beams to the stable rock mass of the underground power plant's sidewalls, forming a solid integral structure. The load acting on the crane beams is transferred to the underground power plant's sidewalls through the anchor bolts and the frictional force at the interface between the beam and the rock mass, fully utilizing the bearing capacity of the surrounding rock. Therefore, rock wall crane beams are widely used in underground power plants.

[0003] The mechanical properties of rock wall crane beams depend not only on the mechanical characteristics of materials such as the surrounding rock, anchor bolts, and reinforced concrete beams, but also on the mechanical behavior of multiple interfaces, including the bonding surfaces between the beam and the rock wall, the anchor bolts and the grout, and the grout and the borehole wall rock. Most existing rock wall crane beams use two rows of tension anchor bolts (cables) and one row of compression anchor bolts (cables) to fix the reinforced concrete beams to the rock wall (see patents CN202020117968.3 / CN202122826384.0 for details). Strengthening the load-bearing capacity of rock wall beams mostly focuses on the anchor bolts, without adding or changing related components, such as increasing the number of anchor bolts, changing the anchor bolt layout, or deepening the anchor bolt penetration depth. However, because the shear strength of the anchor bolts is not high, and they are mainly under tension, this only improves their pull-out resistance; the compressive and shear resistance are not significantly improved. Moreover, shear failure is a brittle failure, which occurs without warning, posing a significant risk to later use. Furthermore, traditional formwork support systems require the erection of full-span scaffolding on the sides of rock face beams during installation, which occupies a significant amount of operating space, increases labor and material costs, and inconveniences construction. Therefore, there are still many key issues to be studied regarding rock face crane beams, and it is necessary to develop new construction methods for rock face beams and concrete pouring. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a rock wall crane beam structure system and construction method for underground powerhouses.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a construction method for a crane beam structure on a rock wall of an underground powerhouse, comprising the following steps:

[0007] Step 1: Excavate the rock wall and install the upper row of pre-embedded tie rods, prestressed anchor rods, pre-embedded steel sections, and lower row of pre-embedded tie rods on the rock wall; the upper row of pre-embedded tie rods and prestressed anchor rods are located on the upper vertical surface of the rock wall, the pre-embedded steel sections are located on the inclined surface of the rock platform, and the lower row of pre-embedded tie rods are located on the lower vertical surface of the rock wall.

[0008] Step 2 involves the construction of the bottom formwork and side formwork. The bottom formwork is located above the lower row of embedded tie rods and is fixed. The side formwork is set vertically and fixed by the upper and lower rows of embedded tie rods.

[0009] Step 3: Connect the prestressed anchor rods to the side formwork via the lapped anchor rods. Place channel steel perpendicular to the direction of the pre-embedded steel in Step 1 on the bottom formwork. Place the steel cage in the space formed by the bottom formwork and the side formwork, and reserve steel bars.

[0010] Step 4: Cast the rock wall beams and cure them;

[0011] Step 5: After the rock wall beams have been cured, remove the side formwork, bottom formwork, and other auxiliary installation frames;

[0012] Step 6: Connect the steel bars reserved in Step 3 to the steel bars of the structural column, and pour the structural column.

[0013] As a further technical solution, the pre-embedded steel section and its adjacent prestressed anchor rod form a triangular arrangement.

[0014] As a further technical solution, the prestressed anchor rods are arranged in two rows, one above the other.

[0015] As a further technical solution, the lower row of pre-embedded tie rods is inclined upwards.

[0016] As a further technical solution, in step 2, first install the frame, then install the I-beam on the top support of the frame, fix the steel tripod on the I-beam, fix the square timber on the steel tripod, and connect the square timber to the bottom formwork.

[0017] As a further technical solution, in step 2, after the bottom formwork is installed, the joint between it and the lower inflection point of the rock wall is filled with wooden strips and mortar.

[0018] As a further technical solution, in step 2, the side mold is located on a steel tripod and connected to the steel tripod; during the installation of the side mold, double-sided adhesive strips are used to fill the gaps between the side mold and the bottom mold and between the side molds; the side mold is fixed by two rows of pre-embedded tie rods, and multiple rows of channel steel with pre-embedded tie rod holes are arranged on the back of the side mold; a steel section is provided behind the channel steel, with holes through the steel plate of the steel section, and double nuts are welded to the pre-embedded tie rods for reinforcement.

[0019] As a further technical solution, in steps 2 and 4, the concrete of the rock wall crane beam is poured in sections, and keyways are set in the concrete of adjacent sections.

[0020] As a further technical solution, a track groove and a water collection pit are installed on the top surface of the crane beam.

[0021] Secondly, embodiments of the present invention also provide an underground powerhouse rock wall crane beam structure system, which is formed by the aforementioned underground powerhouse rock wall crane beam structure construction method.

[0022] The beneficial effects of the above embodiments of the present invention are as follows:

[0023] 1. This invention differs from conventional rock face beam construction methods. To improve the load-bearing capacity of the rock face beam, steel sections are pre-embedded before concrete pouring to replace ordinary anchor rods. Structural columns are constructed at intervals, and transverse channel steel is pre-embedded in the rock face beam above the structural columns. This makes the overall stress on the rock face beam more reasonable. Self-supporting formwork supports are erected, eliminating the need for excessive full-span scaffolding. Tie rods are pre-embedded in the rock face beam to support and hold the high-strength steel side formwork.

[0024] 2. This invention involves pre-embedding steel sections in holes drilled below the crane beam on the rock face, replacing traditional compression anchors. This enhances the compressive strength of the rock face beam while significantly increasing its shear strength, compensating for insufficient shear capacity. Furthermore, the steel sections possess high strength and good toughness, exhibiting ductile failure upon failure, allowing for timely detection and reinforcement measures. They also form a "triangular" arrangement with the prestressed anchors, resulting in a more rational stress distribution.

[0025] 3. The anchor rod of the present invention is a prestressed anchor rod. By applying prestress, the interfacial bonding strength between the rock mass and the cast-in-place body can be improved, and the number of cracks can be reduced.

[0026] 4. The present invention provides structural columns at intervals below the rock wall beam, which can share the load of the rock wall beam and the upper load, thereby improving the load-bearing capacity of the rock wall beam.

[0027] 5. The present invention embeds transverse channel steel in the rock wall beam above the structural column, taking advantage of the high strength of steel to distribute the upper load, making the structural column more uniformly stressed, avoiding stress concentration, and giving full play to its load-bearing capacity.

[0028] 6. This invention performs real-time temperature monitoring during concrete pouring and, if necessary, installs cooling water pipes to cool the concrete, thus preventing excessively high concrete temperatures during large-volume concrete pouring, which could affect the quality and strength of the concrete after molding.

[0029] 7. No need to erect full-span scaffolding on the sides, ensuring the normal use of a portion of the space and avoiding the erection and dismantling of scaffolding.

[0030] 8. The present invention has pre-drilled bolt holes on the upper surface of the rock wall beam, which can be used to install a shock-absorbing device later to reduce the impact of the crane on the rock wall beam and extend the service life of the rock wall crane beam. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a schematic diagram corresponding to the first step in the embodiment;

[0033] Figure 2 , Figure 3 , Figure 4 , Figure 5 This is a schematic diagram corresponding to the second step in the embodiment;

[0034] Figure 6 This is a schematic diagram corresponding to the third step in the embodiment;

[0035] Figure 7 This is a schematic diagram corresponding to the fourth step in the embodiment;

[0036] Figure 8 This is the final schematic diagram;

[0037] In the diagram: 1. Embedded tie rod, 2. Prestressed anchor rod, 3. Embedded steel section, 4. Embedded tie rod; 5. I-beam, 6. Scaffolding, 7. Steel triangular frame; 8. Square timber, 9. Bottom formwork, 10. Anchor head, 11. Steel section, 12. Side formwork, 13. Channel steel, 14. Rear-lapped anchor rod, 15. Horizontal channel steel, 16. Sump, 17. Track groove, 18. Reserved bolt holes, 19. Structural column, 20. Rock wall beam. Detailed Implementation

[0038] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves, and do not limit the structure. They are merely for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or component 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.

[0041] As described in the background section, there are shortcomings in the existing technology. In order to solve the above-mentioned technical problems, this invention proposes a rock wall crane beam structure system for underground powerhouses and a self-supporting construction method.

[0042] In a typical embodiment of the present invention, such as Figures 1-8 As shown; the construction method of the underground powerhouse rock wall crane beam structure system proposed in this invention is as follows:

[0043] 1. Construction of prestressed anchor bolts and pre-embedded steel sections

[0044] Before constructing the rock face beam, some conventional anchor rods (cables) were replaced with pre-embedded steel sections. The construction of prestressed anchor rods 2, pre-embedded tie rods 1 and 4, and pre-embedded steel sections 3 was carried out first, using a "grouting first, then anchor rod insertion" construction method. The specific construction plan is as follows:

[0045] 1-1 Rock Wall Excavation: First, rock wall excavation is carried out. After the excavation is completed, the cross-section is leveled, the surface fault mud and loose media are cleaned, and the rock surface is washed with a high-pressure air and water gun to ensure that the rock surface is clean and moist, without under-excavation and loose rocks before the foundation surface can be inspected.

[0046] 1-2 Measurement and Marking: Based on the required locations for the project, measure and mark the positions of each prestressed anchor rod 2 and the embedded steel section 3, and mark them accordingly. Specific markings can be made with red paint; use "×" and "○" for the two rows of anchor rods, and "+" and "-" for the upper and lower rows of tie rods, respectively; use "+" and "-" for the lower inserted steel section. This designation is used for differentiation and to facilitate multi-arm drilling.

[0047] 1-3 Construction of prestressed anchor rod 2 and pre-embedded tie rod 1, pre-embedded tie rod 4: Anchor rod holes and pre-embedded tie rod holes are drilled using a multi-arm drill. After drilling, the borehole is cleaned with high-pressure air to remove residue and scum from the hole walls, and the water inside the hole is dried. Specifically, the hole diameter is Ф70mm. Drilling is carried out according to the measured points. A "three-stage rod calibration method" is used to ensure drilling accuracy: initially, only rotation is performed without impact. After the drill bit penetrates the rock layer, the first calibration is performed. If the drilling accuracy meets the requirements, impact is then performed. After the impactor penetrates the rock layer, a second calibration is performed. If the accuracy meets the requirements, drilling continues. After the first drill bit penetrates the rock layer, a third calibration is performed. Only if the accuracy meets the requirements can drilling continue. Two sets of stabilizers are added to the first section of the drill rod to ensure the accuracy of the drill rod. After drilling is completed, the borehole is cleaned with high-pressure air to remove residue and scum from the hole walls, and the water inside the hole is dried.

[0048] After drilling 1-4 is completed, grouting is performed. The grout used is M20-M30 cement mortar. To ensure full grouting, before grouting, the grouting pipe is inserted into the bottom of the hole and then pulled out 50mm-100mm. Grouting is performed throughout the hole using a grouting machine with a grouting pressure of not less than 5MPa. During the grouting process, the grouting pipe is slowly pulled out from the bottom of the hole. After the mortar is filled, the anchor sections of the pre-embedded anchor rod 2, pre-embedded tie rod 1, and pre-embedded tie rod 4 should be quickly inserted into the hole. The hole must be temporarily sealed during insertion to prevent excessive mortar overflow. To facilitate the later placement of the reinforcing cage and installation of the formwork, and to reduce the disturbance to the pre-embedded anchor rod 2 during construction, the exposed length of the pre-embedded anchor rod 2 extends 0.5m-1m beyond the rock surface.

[0049] After curing is completed and the reinforcement and formwork are finished, overlap the other anchor rods with the pre-embedded anchor rod 2. When the rod depth reaches the designed anchorage length, fill the hole with mortar, then temporarily seal the hole, and remove the mortar after it has initially set. Then carry out curing of the anchorage end for no less than 5-7 days. During this period, to save time, reinforcement and formwork can be carried out.

[0050] 1-5 Constructing the anchoring holes for the pre-embedded steel section 3: A cantilever trolley combined with manual labor is used for construction. The holes for the pre-embedded steel section 3 are formed using a water drill. Once the designed depth of the pit is reached, drilling must continue for 1-2 minutes to prevent the bottom of the pit from failing to reach the designed hole diameter. The hole size is 5-10cm larger than the dimensions of the pre-embedded steel section 3, the drilling depth is 80-100cm, and the hole spacing is 1-1.5m.

[0051] 1-7 Insert the pre-embedded steel section 3 and grout: After drilling, clean the hole to ensure there is no sediment or water residue. Then insert the pre-embedded steel section 3 into the borehole. Use a locator to position the pre-embedded steel section 3 at the center of the hole to prevent direct contact with the rock mass. Then perform grouting. Cement-based materials or rebar adhesive can be used for the grout. Although the hole is relatively shallow, the drilling direction is horizontal, so pressure grouting is necessary to prevent inadequate grouting. During grouting, sealing is required to prevent excessive leakage of the grout.

[0052] 1-8 Quality Inspection: After the prestressed anchor rods 2 reach a certain age, a quality inspection shall be carried out on the prestressed anchor rods 2 according to the design requirements. Three days after the completion of construction, non-destructive testing of the prestressed anchor rods 2 shall be carried out, with a sampling rate of 100%. Twenty-eight days later, pull-out force testing shall be carried out, with a testing rate of 3 rods out of 200 rods.

[0053] A schematic diagram showing the completion of this step is shown below. Figure 1 As shown, on the excavated rock platform, from top to bottom, a row of pre-embedded tie rods 1, two rows of prestressed anchor rods 2, a row of pre-embedded steel sections 3, and a row of pre-embedded tie rods 4 are installed sequentially; the pre-embedded steel sections 3 are fixed on the inclined surface of the rock platform; the pre-embedded tie rods 1 and prestressed anchor rods 2 are fixed on the vertical surface at the top of the inclined surface of the rock platform, and the pre-embedded tie rods 4 are fixed on the vertical surface at the bottom of the inclined surface of the rock platform.

[0054] 2. Template erection

[0055] To ensure a high appearance quality for the rock face beams, bamboo plywood was used for the bottom formwork of the inclined surface, standardized steel formwork was used for the side formwork of the vertical surface, and wooden formwork was used for the end caps and keyway formwork. Gaps between the inclined formwork and the bedrock surface were filled with wooden strips and mortar. Specific construction requirements and steps are as follows:

[0056] 2.1 Scaffolding erection: First, install scaffolding 6, and then install I-beam steel 5 on the top support of scaffolding 6 to support steel tripod 7;

[0057] 2.2 Bottom formwork support construction: Install steel tripod 7. Steel tripod 7 is prefabricated and installed in place by a crane and manual labor. Steel tripod 7 is connected to the square timber at the bottom of bottom formwork 9 by three 10×8cm square timbers in the middle, each with a length of 6m. Square timbers 8 are connected to each other with nails, and square timbers 8 are connected to steel tripod 7 with bolts.

[0058] 2.3 Erection of Bottom Formwork 9: Bottom formwork 9 is made of prefabricated bamboo plywood, with a single piece width of 1.5m. Before installation, the formwork is erected according to the edge lines, center lines, and elevation points provided by the surveying and layout. Bottom formwork 9 is positioned using a crane in conjunction with manual labor. Bottom formwork 9 is installed at an angle. The bottom formwork 9 is connected to the square timber 8 at the bottom of bottom formwork 9 with steel nails. After the bottom formwork 9 is installed, its elevation and horizontal position are checked again using surveying. After the bottom formwork 9 is installed, the joint between it and the rock platform at the turning point is filled with wooden strips and mortar.

[0059] 2.4 Installation and Fixing of Side Formwork 12: Side formwork 12 is positioned on the angle steel support of the steel tripod 7 using workers and a crane (side formwork 12 is installed vertically) and tightly bolted to it. During installation, double-sided adhesive strips are used to fill the gaps between side formwork 12 and bottom formwork 9, as well as between side formwork 9. A release agent (salad oil) is applied to the formwork surface. The formwork must be tightly assembled, with no misalignment between joints. After assembly, the entire surface of the formwork must be flat and smooth. Side formwork 12 is reinforced using pre-embedded tie rods. The method is as follows: side formwork 12 is fixed using two rows of pre-embedded tie rods 1 and 4. Behind side formwork 12, multiple rows of channel steel with pre-embedded tie rod holes are arranged vertically at both the top and bottom. Behind the channel steel, there is a steel section with perforations on the steel plate, and double nuts are securely welded to the pre-embedded tie rods for reinforcement.

[0060] 3. Reinforcing bar binding and installation of embedded parts

[0061] After the formwork for the rock face beam is installed, the reinforcing bars are installed according to the positions of the prestressed anchor rods 2 and the embedded steel sections 3. Then, the other reinforcing bars and embedded parts of the beam are installed in the correct sequence. Specific construction requirements and steps are as follows:

[0062] 3.1 Overlapping Anchor Rods: After all the formwork is installed, the cantilever trolley, in conjunction with manual labor, overlaps the rear-attached anchor rods 14 with the prestressed anchor rods 2. The overlap method uses a straight threaded sleeve connection. The free section of the prestressed anchor rod 2 is coated with anhydrous grease and covered with a polyethylene plastic sleeve. The sleeve diameter should be slightly larger than the outer diameter of the prestressed anchor rod 2. The joint with the anchoring section is sealed tightly with a sealing plug. Prestress is then applied to the prestressed anchor rod 2 using the pre-tensioning method.

[0063] 3.2 In the tension zone, the ends of the lapped joints of plain round steel bars shall be bent into hooks, while the ends of the lapped joints of threaded steel bars shall not be bent into hooks. The lapped joints of the steel bars shall be secured with binding wire at the center and both ends, with at least three bindings. When steel bars are connected by arc lap welding, the axes of the two steel bars in the lapped joint shall be on the same straight line. Because the structural columns will be cast separately later, steel bars need to be reserved at the corresponding locations to connect with the structural column steel bars.

[0064] 3.3 The installation positions of all embedded parts were determined by measurement and layout. The horizontal embedded channel steel 15, bridge and track bolts were fixed to the steel mesh by manual arc welding. The locations where water and gas pipes, cable pipes and drainage pipes passed through the steel mesh were fixed with "well"-shaped reinforcing ribs by manual arc welding. The upper and lower ends were placed on the template surface and sealed. For steel pipes that needed to extend outside the template, several round holes were drilled at the template opening positions to form the opening edge line. Finally, they were manually chiseled out. The gap between the steel pipe and the template was sealed with white glue. Concrete pouring could only be carried out after the embedded parts were inspected and qualified.

[0065] 4. Concrete pouring

[0066] The concrete pouring process is divided into two parts: the rock wall crane beam pouring and the structural column pouring. The rock wall beam is poured first, followed by the structural columns using the pre-reserved reinforcement bars in the rock wall beam. The rock wall crane beam concrete is poured in sections, each approximately 7m-10m long. The pouring proceeds from the installation bay towards the auxiliary plant, using a skip-section pouring method. Keyways are installed between adjacent sections. The specific construction steps are as follows:

[0067] 4.1 Before pouring the concrete for the crane beam, the surface fault mud and loose media must be thoroughly cleaned. Loose rocks, wall-footing debris, and other accumulated materials within the concrete pouring area of ​​the rock face beam must be manually removed, and the rock surface must be washed with a high-pressure water jet to ensure it is clean, moist, free of under-excavation, and free of loose rock before the foundation surface can be inspected.

[0068] 4.2 Using 10.0m 3 Concrete mixer trucks transport concrete for rock wall beams, taking into account concrete pouring capacity and specific surface conditions to ensure adequate intervals between pours. After the mix is ​​poured into the mixer, an infrared thermometer is used for temperature monitoring to keep the mixing temperature below 28°C.

[0069] 4.3 Before pouring concrete, a slump test should be conducted to ensure the quality of the concrete mix. Pouring can begin after the concrete quality inspection is passed. For the rock face beam concrete, a crane and a hoisting bucket are the primary means of placement, with workers standing on a cantilever trolley to assist in the mechanical pouring. The rock face beam concrete is poured in layers from bottom to top, with each layer thickness controlled between 30 and 50 cm. Cooling water pipes are not installed in the first layer of concrete. Whether or not cooling water pipes are needed is determined based on temperature monitoring of the first layer of rock face beam concrete. If the internal and external temperature difference does not meet the specifications and design requirements, then pre-installed temperature-controlled water pipes are required.

[0070] 4.4 After manual leveling, immediately insert a thermometer 10cm into the concrete to measure the concrete temperature. Once the temperature control conditions are met, use an immersion vibrator to compact the concrete, avoiding contact with the reinforcing bars, embedded parts, and anchor rods as much as possible. If necessary, supplement with manual compaction. Install an attached vibrator on the side formwork to ensure a smooth concrete surface on the side of the rock wall beam. If formwork loosening occurs during vibration, further prestress can be applied to the embedded tie rods to prevent grout leakage.

[0071] 4.5 After the concrete pouring is completed, promptly organize manual finishing and smoothing (the area where the second-phase concrete was poured does not need smoothing, but should be roughened). When smoothing, the surface should be smoothed from the outside towards the drainage holes to ensure smooth drainage. During the smoothing process, strictly control the elevation of the top surface of the crane beam, requiring the top of the crane beam to be flat, smooth, and accurately oriented, and ensure that the embedded parts are exposed above the concrete surface.

[0072] 4.6 Water curing should be carried out promptly 12-18 hours after concrete pouring and covering with felt and plastic film. The formwork of the rock wall beam can only be removed after the concrete has reached the design strength.

[0073] 4.7 Remove the formwork, embedded tie rods, and supporting scaffolding from the rock face beams. Clean the reserved tracks and bolt holes, and install vibration damping devices.

[0074] 4.8 Roughen the contact area between the structural column 19 and the rock wall beam 20 and wet it with water. Level the rock wall, lap the reserved steel bars of the rock wall beam with the steel bars of the structural column, and then pour the structural column.

[0075] Furthermore, this embodiment also provides an underground powerhouse rock wall crane beam structure system, which is formed by the underground powerhouse rock wall crane beam structure construction method described above.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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.

Claims

1. A construction method for a crane beam structure on the rock wall of an underground powerhouse, characterized in that, Before pouring concrete, steel sections are pre-embedded to replace ordinary anchor rods, structural columns are constructed at intervals, and transverse channel steel is pre-embedded in the rock wall beams above the structural columns. This includes the following steps: Step 1: Excavate the rock wall and install the upper row of pre-embedded tie rods, prestressed anchor rods, pre-embedded steel sections, and the lower row of pre-embedded tie rods on the rock wall. The upper row of pre-embedded tie rods and prestressed anchor rods are located on the upper vertical surface of the rock wall, the pre-embedded steel sections are located on the inclined surface of the rock wall, and the lower row of pre-embedded tie rods are located on the lower vertical surface of the rock wall. The pre-embedded steel sections and the adjacent prestressed anchor rods form an inverted triangular arrangement. Step 2 involves the construction of the bottom formwork and side formwork. The bottom formwork is located above the lower row of embedded tie rods and is fixed. The side formwork is set vertically and fixed by the upper and lower rows of embedded tie rods. The bottom formwork of the inclined beam is made of bamboo plywood, the side formwork of the vertical face is made of prefabricated steel formwork, and the end cap formwork and keyway formwork are assembled from wooden formwork. The gaps between the inclined formwork and the bedrock surface are filled with wooden strips and mortar. The specific construction requirements and steps are as follows: 2.1 Scaffolding erection: First, install the scaffolding, and then install I-beam steel on the top support of the scaffolding to support the steel tripod; 2.2 Bottom formwork support construction: Install steel tripods. The steel tripods are prefabricated and installed in place by a crane and manual labor. The steel tripods are connected to the square timber at the bottom of the bottom formwork through the middle square timber. The square timber is connected to the square timber with nails, and the square timber is connected to the steel tripod with bolts. 2.3 Bottom Formwork Erection: The bottom formwork is made of prefabricated bamboo plywood. Before installation, the formwork is erected according to the edge lines, center lines, and elevation points provided by the surveying and layout. The bottom formwork is positioned using a crane in conjunction with manual labor. The bottom formwork is installed at an angle, and the square timber at the bottom of the bottom formwork is connected to the bottom formwork with steel nails. After the bottom formwork is installed, its elevation and horizontal position are checked by surveying. After the bottom formwork is installed, the joint between it and the rock platform at the turning point is filled with wooden strips and mortar. 2.4 Side Formwork Installation and Fixing: The side formwork is positioned on the angle steel supports of the steel tripod using workers and a crane, and is tightly connected to the side formwork with bolts. During installation, double-sided adhesive strips are used to fill the gaps between the side formwork and the bottom formwork, as well as between the side formworks. Release agent is applied to the formwork surface. The formwork must be assembled tightly, with no misalignment between the joints. After assembly, the entire surface of the formwork must be flat and smooth. The side formwork is reinforced using pre-embedded tie rods. The method is as follows: the side formwork is fixed with two rows of pre-embedded tie rods, and multiple rows of channel steel with pre-embedded tie rod holes are arranged vertically on both the upper and lower sides behind the side formwork. Behind the channel steel, there is a steel section with holes through the steel plate, and double nuts are firmly welded to the pre-embedded tie rods for reinforcement. Step 3: Connect the prestressed anchor rods to the side formwork via the lapped anchor rods. Place channel steel perpendicular to the direction of the steel section in Step 1 on the bottom formwork. Place the steel cage in the space formed by the bottom formwork and the side formwork, and reserve steel bars. Step 4: Cast the rock wall beam and cure it, leaving bolt holes on the upper surface of the rock wall beam; Step 5: After the rock wall beams have been cured, remove the side formwork, bottom formwork, and other auxiliary installation frames; Step 6: Connect the steel bars reserved in Step 3 to the steel bars of the structural column, and pour the structural column.

2. The construction method for the underground powerhouse rock wall crane beam structure as described in claim 1, characterized in that, In step 2, first install the frame, then install the I-beam on the top support of the frame, fix the steel tripod on the I-beam, fix the square timber on the steel tripod, and connect the square timber to the bottom formwork.

3. The construction method for the underground powerhouse rock wall crane beam structure as described in claim 2, characterized in that, In step 2, after the bottom formwork is installed, the joint between it and the lower bend of the rock wall is filled with wooden strips and mortar.

4. The construction method for the underground powerhouse rock wall crane beam structure as described in claim 2, characterized in that, In step 2, the side mold is located on and connected to the steel tripod; during the installation of the side mold, double-sided adhesive strips are used to fill the gaps between the side mold and the bottom mold, as well as between the side molds; the side mold is fixed by two rows of pre-embedded tie rods, and multiple rows of channel steel with pre-embedded tie rod holes are arranged on the back of the side mold; a steel section is provided behind the channel steel, with holes through the steel plate, and double nuts are welded to the pre-embedded tie rods for reinforcement.

5. The construction method for the underground powerhouse rock wall crane beam structure as described in claim 1, characterized in that, In steps 2 and 4, the concrete for the rock wall crane beam is poured in sections, and keyways are set in the concrete of adjacent sections.

6. The construction method for the underground powerhouse rock wall crane beam structure as described in claim 1, characterized in that, The top surface of the crane beam is equipped with a track groove and a water collection pit.

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