Ultrahigh slope revetment supporting structure suitable for different soil layers and construction method

Abstract

The invention belongs to an ultrahigh side slope revetment supporting structure suitable for different soil layers and a construction method. According to the ultrahigh side slope revetment supporting structure and the construction method, supporting schemes of all areas are designed according to geological exploration and supporting area division of an ultrahigh side slope; the supporting method that locking anchor rods, system anchor rods, pre-stressed anchor cables, an outer sealing and spraying concrete layer and inner cement grouting are combined is used for clay and gravel soil areas, and the supporting method that anchoring steel meshes and locking anchor rods are combined is used for rock areas. The overall stability and safety of the supporting structure can be greatly improved, and potential landslide and collapse risks are reduced. The method is high in adaptability, can cope with various different geological conditions, can achieve effective supporting on clay layers, gravel layers and other complex soil layer structures, and can be used in regions with complex geological conditions or varied regions.

Description

Technical Field

[0001] The invention relates to a super-high slope bank protection support structure suitable for different soil layers and a construction method. Background Art

[0002] A super-high slope refers to a super-high mountain slope with an angle between the slope surface and the horizontal plane between 50° and 90°, and a slope straight-line height greater than 100m. Super-high slope bank support refers to the support of the mountains on both sides of the reservoir dam, and the support of the mountains on the sides of roads, railways, bridges, and buildings. Super-high slope bank support has factors such as high height, steep slope, and complex force. Traditional super-high slope bank support structures often adopt a unified design and construction method. This single construction method is only set for a single super-high slope bank protection geological condition, but cannot effectively adapt to the different geological conditions of super-high slope bank protection, resulting in the inability to guarantee the stability and safety of super-high slope bank protection support, and then the inability to guarantee the stability and safety of reservoir dams, roads, railways, bridges, and buildings.

[0003] In different types of super-high slope revetment geology, such as clay layer, gravel layer, rock layer, etc., their physical and mechanical properties are significantly different, such as permeability, strength, stability, etc., which requires that different support measures be adopted according to the characteristics of different soil layers when excavating and supporting super-high slopes to ensure the stability and safety of the overall structure. However, there is currently a lack of an effective method to solve this problem in a targeted manner, especially in the support engineering of super-high slopes. How to take corresponding zoning support measures according to the different characteristics of the soil layers and how to achieve the effective integration of these measures have become key technical issues that need to be solved urgently. Summary of the invention

[0004] The object of the present invention is to provide a super-high slope bank protection support structure and a construction method suitable for different soil layers, so as to solve the problems raised in the above-mentioned background technology.

[0005] To this end, the super-high slope revetment support structure and construction method applicable to different soil layers of the present invention include the following steps: (1) Geological survey and support area division of super-high slopes: Conduct detailed geological survey of super-high slope revetments, including drilling sampling, soil layer analysis, and hydrogeological surveys, to determine the soil layer structure, type, and distribution of super-high slope revetments. Based on the physical and mechanical properties of the soil layer of the super-high slope revetments obtained from the survey, the slopes are divided into several support areas according to the soil layer conditions, stability, and water content. Each support area is divided into clay area, gravel area, and rock area according to the soil layer type. (2) Prepare construction equipment, tools, anchor rods and various raw materials; (3) Remove the backing layer of the super-high slope revetment, and excavate from top to bottom to form three steps of upper, middle and lower steps. Blasting, excavation and slag removal are carried out inward to the solid rock layer, clay layer or gravel layer. The horizontal excavation length of the upper step construction surface is at least 20m, the horizontal excavation length of the middle step construction surface is at least 17m, and the horizontal excavation length of the lower step construction surface is at least 14m. The angle between the construction surface of each step and the horizontal plane is less than 70°. (4) Design support schemes for each area based on geological survey and support area division of super-high slopes: (a) For clay areas, a support method combining locking anchors, system anchors, prestressed anchor cables, external mesh sprayed concrete layers and internal cement grouting is used; (b) For gravel soil areas, a support method combining locking anchors, system anchors, prestressed anchor cables, external mesh sprayed concrete layers and internal cement grouting is used; (c) Use a support method that combines anchor steel mesh and locking anchor rods in rock areas; (5) Connection between various regions: (a) The connection between the clay area and the rock area: the inner end of the locking anchor rod around the rock area extends into the adjacent clay area, and the surrounding area of ​​the anchor steel mesh in the rock area extends to cover the clay area; (b) The connection between the clay area and the gravel area: the peripheries of the mesh sprayed concrete layers in the clay area and the gravel area are connected to each other, cement grouting is carried out simultaneously in the clay area and the gravel area, the inner ends of the locking anchor rods around the gravel area extend into the clay area, and the inner ends of the locking anchor rods around the clay area extend into the gravel area; (c) The connection between the gravel soil area and the rock area: the inner ends of the locking anchor rods around the rock area extend into the gravel soil area, and the anchor steel mesh around the rock area extends to cover the gravel soil area; (d) The support construction of the same terrace surface is carried out in the clay area, gravel area and rock area in sequence; (6) The horizontal excavation length of each step construction surface should differ by at least 5m. The upper step construction should be carried out first. When the upper step construction surface reaches the designed construction surface, the upper step construction surface should be supported immediately. Then the middle step excavation should be carried out. When the middle step construction surface reaches the designed construction surface, the middle step construction surface should be supported immediately. Finally, the lower step excavation should be carried out. When the lower step construction surface reaches the designed construction surface, the lower step construction surface should be supported immediately. (7) The outer end surface of the clay and gravel soil area in each step support surface is recessed 12 cm from the outer end surface of the rock area. After support, the outer end surface of the mesh sprayed concrete layer at the outer end of the clay and gravel soil area in the same step support surface is flush with the outer end surface of the rock area in the same step, and the outer ends of the locking anchor rods and system anchor rods are exposed 12 cm outside the outer end surface of the mesh sprayed concrete layer; (8) After the locking anchor rod construction or locking anchor rod grouting construction is carried out on the same step rock area, the anchor steel mesh is fixed on the end of the locking anchor rod on the outer end face of the protruding step rock area, and the anchor steel mesh is extended to cover the outer end face of the clay and gravel soil area in the same step support surface and is fixed to the locking and system anchor rod outer end corresponding to the end face of the mesh sprayed concrete layer exposed at the inner and outer ends of the area, forming an anchor steel mesh layer covering the same step rock area, clay, and gravel soil area; (9) A sprayed concrete layer is placed on the anchored steel mesh layer in the rock area, clay, and gravel soil area of ​​the same step, and after curing, an ultra-high slope bank support with different soil layers on the same step is formed; (10) Construction at the intersection of each step construction surface: After the adjacent step support surface is completed, the construction at the intersection of the adjacent steps is carried out. A platform steel mesh is laid on the construction platform at the intersection of each step construction surface. The two ends of the platform steel mesh are respectively connected to the outer ends of the steel mesh on the upper and lower ends of the adjacent step construction surface. The overlap length of the two ends of the platform steel mesh when horizontally extended is 20 cm. Then, C25 concrete is poured or sprayed on the platform steel mesh to form a platform concrete layer. The thickness of the platform concrete layer is 20 cm. The two ends of the platform concrete layer are connected to the sealing and spraying concrete layers on the upper and lower ends of the adjacent step construction surface to complete the super-high slope bank protection support of different soil layers of each step.

[0006] As a further description of the above technical solution: the thickness of the sealing sprayed concrete layer on the anchoring steel mesh layer is 12 cm.

[0007] As a further description of the above technical solution: the mesh size of the anchoring steel mesh is 20cm×20cm, the mesh steel bar model is φ8mm, the anchoring steel mesh is made by straightening and cutting the steel bars at the on-site processing camp, and then transporting them to the construction site to be tied and woven into a mesh, which is laid from top to bottom. When docking, the overlap between the anchoring steel meshes is not less than 5cm, and they are tied with φ1.2mm iron wire at intervals of 1m.

[0008] As a further description of the above technical solution: the grid size of the platform steel mesh is 0.2m×0.2m, and the grid steel bar model is φ12mm. In order to facilitate the installation of the mesh, the platform steel mesh is first processed into a mesh with a length and width of 100cm to 200cm.

[0009] As a further description of the above technical solution: the support of each step construction surface includes: (a) Drainage holes are drilled in each area of ​​each step support surface: the drainage holes in the rock, clay, and gravel areas of each step support surface are 4 to 5 meters long, 56 mm in diameter, 8 degrees in elevation, arranged in a plum blossom shape, and 3 meters apart from each other. Bottom drainage holes are added to the bottom of the rock area of ​​each step support surface, with a length of 8 to 9 meters, a drainage hole diameter of 56 mm, an 8 degrees in elevation, arranged in a plum blossom shape, and 4 meters apart from each other; (b) Carry out locking anchor construction in clay and gravel areas: the outer end surface of the clay and gravel areas in each step support surface is recessed into the outer end surface of the rock area by 12 cm. Each locking anchor is located at the upper part of each clay and gravel area and the periphery of the intersection with the rock, clay and gravel areas. In the upper part of each clay and gravel area, based on the on-site construction conditions, ROC-D9 hydraulic drilling rig, YG-80 disc drill and multi-arm drill are used to drill holes for each anchor. The anchor hole length is 12 m, arranged in a plum blossom shape, and the spacing between adjacent anchor holes is 2. m, put the grouting pipe in the hole, and the grouting pump injects cement slurry into the clay and gravel soil areas through the grouting pipe. The grouting pressure in the gravel soil area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting meets the design requirements, the anchor hole should be filled with mortar and HRB400 steel bars with a length of 12.24m and a diameter of 32mm should be inserted to form a locking anchor. The length of the rod body inserted into the hole should not be less than 95% of the design length, and the outer end of the locking anchor should be exposed 12cm outside the excavated rock area surface or the mesh shotcrete layer; The locking anchors at the intersection with the rock, clay, and gravel areas shall be constructed such that the front of the locking anchors at the intersection extends into the adjacent areas. The locking anchors in the adjacent areas shall be 2.5m apart. The adjacent locking anchors in the adjacent areas shall be arranged crosswise with opposite inclinations. The drilling length shall be 15-20m. After the anchor holes are drilled and grouted, the holes shall be filled with mortar and HRB400 steel bars with a length of 15.24-20.24m and a diameter of 32mm shall be inserted to form locking anchors. The outer ends of the locking anchors shall be exposed 12cm outside the excavated rock area or the sprayed concrete surface. (c) Carry out system anchor construction in clay and gravel areas: Each system anchor is located in the middle and lower parts of each clay and gravel area. In the middle and lower parts of each clay and gravel area, according to the on-site construction conditions, ROC-D9 hydraulic drilling rig, YG-80 disc drill and multi-arm drill are used to drill holes for each system anchor. The anchor hole length is 9m, the downward inclination angle is 10°, and it is arranged in a plum blossom shape. The spacing between adjacent anchor holes is 2m. Grouting pipes are placed in the holes, and the grouting pump passes through the grouting pipes. Pour cement slurry into the clay and gravel soil areas. The grouting pressure in the gravel soil area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting reaches the design requirements, the anchor hole should be filled with mortar and a 9.24m long HRB400 steel bar with a diameter of 28mm should be inserted to form a system anchor. The length of the rod inserted into the hole should not be less than 95% of the design length. The outer end of the system anchor is exposed 12cm outside the excavated rock surface or the sprayed concrete surface; (d) Carry out mesh spraying concrete construction in clay and gravel areas: hang mesh on the exposed ends of system anchors and locking anchors in clay and gravel areas, and then use a sprayer to spray concrete on the mesh to form a mesh spraying concrete layer. The thickness of the mesh spraying concrete layer is 12 cm, the first layer is 4 cm thick, and the second and third layers are each 4 cm thick. The outer end surface of the mesh spraying concrete layer is flush with the outer end surface of the rock area; (e) Construction of prestressed anchor cables in clay and gravel areas: The prestressed anchor cables are located in the middle of the gravel area and the top of the clay area. Adjacent prestressed anchor cables are set at an interval of 6m. The anchor cable drilling length is 40-50m and the downward inclination angle is 10°. The anchor cables are made of Q235, 6×19 1000KN prestressed anchor cables with a diameter of 30-40mm. Grouting pipes are placed in the boreholes. Grouting pumps inject cement slurry into the clay and gravel areas through the grouting pipes. The grouting pressure in the gravel area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting meets the design requirements, the grouting pipes are removed, and the cable body anchoring section is grouted in the cable hole. Anchor cables with a length of 40.3-50.3m are inserted into the cable holes, and then tied and filled with grout at the hole mouths. The expansion type positioning stop ring is used to cast the anchor pier concrete seat at the hole mouth, install the hole mouth guide pipe and anchor pad, and when the bearing strength of the anchor pier concrete seat and the consolidation slurry reaches the construction requirements, the anchor cable is tensioned. The tensioning force increases step by step, and its maximum value is 1.05-1.1 times the design load of the anchor cable. It is locked after stabilizing the pressure for 10-20 minutes. Within 48 hours after locking, if the anchor cable stress drops to 10% below the design value, compensation tensioning should be carried out. The sealing hole backfill grouting is carried out 28 days after the completion of the compensation tensioning work. Before the sealing hole backfill grouting, it should be confirmed that the anchor cable stress has reached the stable design value. After the grouting is completed, the steel strand bundle outside the anchor should be cut off except for 15cm. The end of the external anchor or steel strand bundle should be sealed and protected with concrete, and the thickness of the concrete protection should be not less than 10cm. (f) Locking anchors and anchor steel meshes are constructed in the rock area of ​​the same step. Each locking anchor is distributed in the rock area and around the intersection with the clay and gravel areas. In the rock area, ROC-D9 hydraulic drilling rigs, YG-80 disc drills, and multi-arm drills are used to drill holes for each locking anchor. The length of each locking anchor hole in the rock area is 12m, arranged in a plum blossom shape, and the spacing between adjacent locking anchor holes is 2m. After the anchor hole is grouted, the borehole should be filled with mortar and HRB400 steel bars with a length of 12.12m and a diameter of 32mm should be inserted to form a locking anchor. If there are cracks and looseness in the rock area of ​​the same step, a grouting pipe can be placed in the locking anchor hole first, and the grouting pump can inject cement slurry into the rock through the grouting pipe. The grouting pressure in the rock area is 1-1.5MPa. After the grouting meets the design requirements, the anchor hole should be filled with mortar and HRB400 steel bars with a length of 12.12m and a diameter of 32mm should be inserted. The length of the rod body inserted into the hole should not be less than 95% of the design length. The outer end of the locking anchor is exposed 12cm outside the excavated rock area surface or the mesh shotcrete layer to form a locking anchor. The locking anchor construction in the rock area bordering the clay area and gravel area of ​​the same platform is that the front part of the locking anchor in the intersecting area extends into the adjacent area. The locking anchors in the adjacent area are 2.5m apart and the drilling length is 15-20m. After the anchor hole is grouted, the borehole should be filled with mortar and HRB400 steel bars with a length of 15.12-20.12m and a diameter of 32mm should be inserted to form a locking anchor. The outer end of the locking anchor is exposed 12cm outside the excavated rock area surface or the sprayed concrete surface; An anchoring steel mesh is fixed on the end of the locking anchor rod on the outer end face of the protruding step rock area, and the anchoring steel mesh extends to cover the outer end face of the clay and gravel soil area in the same step step support surface and is fixed to the outer end head of the locking and system anchor rod corresponding to the end face of the mesh sprayed concrete layer exposed at the inner and outer ends of the area, forming an anchoring steel mesh layer covering the rock area, clay, and gravel soil area of ​​the same step step; (g) A sprayed concrete layer is placed on the anchored steel mesh layer in the rock area, clay and gravel soil area of ​​the same step, and after curing, an ultra-high slope bank support with different soil layers on the same step is formed.

[0010] As a further description of the above technical solution: the grouting uses cement slurry with a water-cement ratio of 1:1.

[0011] As a further description of the above technical solution: the construction of the locking anchor rods, system anchor rods and prestressed anchor cables is completed on the erected stepped scaffolding.

[0012] As a further description of the above technical solution: the mesh size of the mesh sprayed concrete layer is 20cm×20cm, and the mesh steel bar model is φ6mm.

[0013] As a further description of the above technical solution: the weight ratio of the sprayed concrete is: cement: fine aggregate: coarse aggregate: water: accelerator: water reducer = 1:2.3:2.2:0.48:0.021:0.0075, cement is selected from sulfate-resistant cement that meets national standards, and the cement strength grade is not lower than P.O42.5, fine aggregate (particle size less than 0.5mm) uses hard and durable coarse and medium sand, the fineness modulus should be greater than 2.5, and the moisture content during use is controlled at 5% to 7%; coarse aggregate uses hard and durable pebbles or crushed stones, and the particle size is not more than 15mm.

[0014] The present invention has the following beneficial effects: 1. The present invention can provide stability and safety support for super-high slope revetments in different geological conditions, and further ensure the stability and safety of reservoir dams, roads, railways, bridges, and buildings. The present invention designs corresponding support measures according to the characteristics of different soil layers, thereby greatly improving the overall stability and safety of the support structure and reducing the potential risks of landslides and collapses. The present invention has strong adaptability, and the provided method can cope with a variety of different geological conditions. Whether it is a clay layer, a gravel layer or other complex soil layer structures, it can achieve effective support and can be used in areas with complex or changing geological conditions. Practice has proved that after supporting super-high slope revetments in different geological conditions according to the method of the present invention, they all have good stability and safety. The blasting vibration test of the supported super-high slope revetments shows that under an earthquake state of approximately magnitude 5, the supported super-high slope revetments have no cracking, rockfall, landslides, and collapse phenomena, and have good stability and safety characteristics.

[0015] 2. The present invention adopts support construction divided according to soil layer conditions, which can optimize the construction process while ensuring safety, avoiding the waste of resources and unnecessary cost expenditures that may be caused by the one-size-fits-all traditional construction method. The present invention improves construction efficiency and saves costs by taking the most appropriate support measures for different soil layers.

[0016] 3. The method of the present invention takes into account the long-term characteristics of different soil layers in the natural environment, including adaptability to moisture and temperature changes, and the impact of time changes on soil stability. This can not only improve immediate engineering safety, but also ensure long-term environmental adaptability and structural durability, reducing the need for maintenance and repair. Through precise zoning support strategies, interference and damage to the environment are reduced, especially in ecologically sensitive areas. Compared with traditional large-scale excavation and support methods, this method can better protect the natural landscape and ecological balance, and is in line with the principle of sustainable development.

[0017] 4. The present invention is convenient to construct, does not require large-scale construction machinery, has simple procedures, and is easy to master. The present invention has a good use effect, has the advantages of saving labor and effort during construction, simple construction, fast speed, material saving, high efficiency and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the longitudinal section structure of the present invention for supporting the super-high slope revetment; Figure 2 This is a schematic diagram of the structure for supporting the rock area according to the present invention; Figure 3 This is a schematic diagram of the structure for supporting the gravel area according to the present invention; Figure 4 This is a schematic diagram of the structure of supporting the clay area according to the present invention; Figure 5 It is a schematic diagram of the structure of the present invention for supporting on a stepped scaffold. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described in conjunction with specific embodiments below, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work all belong to the protection scope of the present invention. The construction methods in the following embodiments, unless otherwise specified, are all conventional methods. The materials, devices, equipment, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels.

[0020] Example 1: Figures 1 to 5 As shown, a super-high slope bank protection support structure and construction method suitable for different soil layers include the following steps: (1) Geological survey and support area division of super-high slopes: Conduct detailed geological survey of super-high slope revetments, including drilling sampling, soil layer analysis, and hydrogeological surveys, to determine the soil layer structure, type, and distribution of super-high slope revetments. Based on the physical and mechanical properties of the soil layer of the super-high slope revetments obtained from the survey, the slopes are divided into several support areas according to the soil layer conditions, stability, and water content. Each support area is divided into clay area 3, gravel area 2, and rock area 1 according to the soil layer type. Clay area 3 means clay accounts for more than 70% of the soil in this area, gravel area 2 means gravel accounts for more than 70% of the soil in this area, and rock area 1 means rock accounts for more than 70% of the soil in this area.

[0021] (2) Prepare all construction equipment, tools, anchors and various raw materials, including excavators, concrete wet spraying machines, K500 concrete spraying machines, high-pressure wind and water combined cleaning machines, slurry mixers, hand pneumatic drills, hydraulic drills, YG-80 disc drills, multi-arm drills, grouting pumps, through-type jacks, stretchers, torque wrenches, scaffolding materials, various anchors, explosives, cement, sand and gravel, additives, etc.

[0022] (3) Remove the backing layer 5 of the super-high slope revetment, and excavate from top to bottom to form the upper, middle and lower steps. Blasting, excavation and slag removal are carried out inward to the solid rock layer, clay layer or gravel layer, among which: the horizontal excavation length of the upper step construction surface 6 is at least 20m, the horizontal excavation length of the middle step construction surface 7 is at least 17m, and the horizontal excavation length of the lower step construction surface 10 is at least 14m. The angle between each step construction surface and the horizontal plane is less than 70°. A flat catwalk 18 with a width of about 10m is formed at the intersection of the upper, middle and lower steps to facilitate construction and the construction of a stepped scaffolding 17. The construction of locking anchors, system anchors and prestressed anchor cables on the inclined step construction surfaces is completed on the erected stepped scaffolding 17.

[0023] (4) Design support schemes for each area based on the geological survey and support area division of the super-high slope, including: (a) A support method combining locking anchors 4, system anchors 8, prestressed anchor cables 12, external mesh sprayed concrete layer 13 and internal cement grouting is used for the clay area 3.

[0024] (b) A support method combining locking anchor rods 4, system anchor rods 8, prestressed anchor cables 12, external mesh sprayed concrete layer and internal cement grouting is used for the gravel soil area 2.

[0025] (c) A support method combining an anchoring steel mesh and a locking anchor rod 4 is used for the rock area 1.

[0026] (5) Coordination of various regions, including: (a) The connection between the clay area 3 and the rock area 1: The inner end of the locking anchor rod 4 around the rock area 1 extends into the adjacent clay area 1, and the surrounding area of ​​the anchor steel mesh in the rock area extends to cover the clay area. The periphery refers to the area within 1 to 2 meters within the obvious boundary line (the same below).

[0027] (b) The connection between the clay area 3 and the gravel area 2: The peripheries of the mesh sprayed concrete layer 9 of the clay area and the gravel area are connected to each other, cement grouting is carried out simultaneously in the clay area and the gravel area, the inner ends of the locking anchor rods 4 around the gravel area extend into the clay area, and the inner ends of the locking anchor rods around the clay area extend into the gravel area, and the angle between each locking anchor rod extending into the peripheral area and the horizontal axis of the mountain can be 20° to 40°, and the locking anchor rods inserted in adjacent peripheral areas are staggered, so that the gravel area and the clay area form an integrally stable support structure, which effectively prevents landslides and collapses of the mountain.

[0028] (c) The connection between the gravel soil area and the rock area: the inner ends of the locking anchor rods around the rock area extend into the gravel soil area, and the anchor steel mesh around the rock area extends to cover the gravel soil area.

[0029] (d) The support construction of the same step surface is carried out in the clay area, gravel area and rock area in sequence.

[0030] (6) The horizontal excavation length of each step construction surface should differ by at least 5m. The upper step construction should be carried out first. When the upper step construction surface reaches the designed construction surface, the upper step construction surface should be supported immediately. Then the middle step excavation should be carried out. When the middle step construction surface reaches the designed construction surface, the middle step construction surface should be supported immediately. Finally, the lower step excavation should be carried out. When the lower step construction surface reaches the designed construction surface, the lower step construction surface should be supported immediately.

[0031] (7) The outer end face of the clay and gravel soil area in each step support surface is recessed 12 cm from the outer end face of the rock area. After support, the outer end face of the mesh sprayed concrete layer 9 in the clay and gravel soil area in the same step support surface is flush with the outer end face of the rock area in the same step, and the outer ends of the locking anchor rods and system anchor rods are exposed 12 cm outside the outer end face of the mesh sprayed concrete layer for external hanging and fixing of the anchoring steel mesh.

[0032] (8) After the locking anchor rod construction is carried out on the rock area of ​​the same step, the anchor steel mesh is fixed on the end of the locking anchor rod on the outer end of the protruding step rock area. The anchor steel mesh extends to the outer end of the clay and gravel soil area in the same step support surface and is fixed to the outer end of the locking and system anchor rod corresponding to the end of the mesh sprayed concrete layer exposed at the inner and outer ends of the area, forming an anchor steel mesh layer covering the rock area, clay and gravel soil area of ​​the same step. The mesh size of the anchor steel mesh is 20cm×20cm, and the mesh steel bar model is φ8mm. The anchor steel mesh is made by straightening and cutting the steel bars at the on-site processing camp, transporting them to the construction site, and binding them on site to form a mesh. It is laid from top to bottom. When docking, the anchor steel meshes overlap by no less than 5cm and are tied with φ1.2mm iron wire at a spacing of 1m.

[0033] (9) A sprayed concrete layer 13 is sealed on the anchoring steel mesh layer in the rock area, clay and gravel soil area of ​​the same step. The thickness of the sprayed concrete layer 13 on the anchoring steel mesh layer is 12 cm. After curing, an ultra-high slope bank support with different soil layers on the same step is formed.

[0034] (10) Construction at the intersection of each step construction surface: After the adjacent step support surface is completed, the construction at the intersection of adjacent steps is carried out, including catwalk 18. A platform steel mesh is laid on the construction platform at the intersection of each step construction surface. The mesh size of the platform steel mesh is 0.2m×0.2m, and the mesh steel bar model is φ12mm. In order to facilitate the installation of the mesh, the platform steel mesh is first processed into a mesh with a length and width of 100cm to 200cm. The two ends of the platform steel mesh are respectively connected to the outer pierced heads of the steel mesh at the upper and lower ends of the adjacent step construction surface. The lap length of the two ends of the platform steel mesh is 20cm when it is horizontally extended. Then, C25 concrete is poured or sprayed on the platform steel mesh. After curing, a platform concrete layer 11 is formed. The weight ratio of the platform concrete is cement: water: sand: crushed stone: accelerator: water reducer = 1: 0.47: 2: 2.85: 0.020: 0.008. The crushed stone is hard and durable pebbles or crushed stones with a particle size of no more than 20mm. The cement is sulfate-resistant cement that meets national standards, and the cement strength grade is not less than P.O42.5. The thickness of the platform concrete layer 11 is 20cm. The two ends of the platform concrete layer are connected to the sealing and spraying concrete layers at the upper and lower ends of the adjacent step construction surface to complete the super-high slope bank protection support of different soil layers of each step.

[0035] The support of each step construction surface includes: (a) Drain holes 15 are drilled in each area of ​​each step support surface: the drainage holes 15 in the rock, clay, and gravel areas of each step support surface are 4 to 5 meters long, 56 mm in diameter, 8 degrees in elevation, arranged in a plum blossom shape, and 3 meters apart from adjacent drainage holes. Bottom drainage holes 14 are added to the bottom of the rock area of ​​each step support surface, with a length of 8 to 9 meters, a diameter of 56 mm, an elevation of 8 degrees, arranged in a plum blossom shape, and 4 meters apart from adjacent drainage holes. The drainage holes are used to drain water from the soil layers in each area of ​​each support surface.

[0036] (b) Construction of locking anchor rods 4 in clay and gravel soil areas: the outer end surface of the clay and gravel soil area in each step support surface is recessed into the outer end surface of the rock area by 12 cm. Each locking anchor rod 4 is located at the upper part of each clay and gravel soil area and the periphery intersecting with the rock, clay and gravel soil area. In the upper part of each clay and gravel soil area, combined with the on-site construction conditions, a ROC-D9 hydraulic drill, or a YG-80 disc drill, or a multi-arm drill is used to drill holes for each anchor rod. The anchor rod drilling length is 12 m, the hole diameter is 38 mm, and the arrangement is in a plum blossom shape. The spacing between adjacent anchor rod drilling holes is 2 m. A grouting pipe is placed in the hole, and a grouting pump injects cement slurry into the clay and gravel soil area through the grouting pipe. The grouting adopts cement slurry with a water-cement ratio of 1:1. The grouting pressure in the gravel soil area is 0.8-1.2 MPa, and the grouting pressure in the clay area is 1-2.5 MPa. After the grouting meets the design requirements, pull out the grouting pipe, fill the anchor hole with mortar and insert HRB400 steel bar with a length of 12.24m and a diameter of 32mm to form a locking anchor. The length of the rod inserted into the hole should be not less than 95% of the design length. The outer end of the locking anchor should be exposed 12cm outside the excavated rock area or the mesh shotcrete layer 9.

[0037] The locking anchors are constructed around the intersections with rock, clay, and gravel areas. The front of the locking anchors at the intersections extends into the adjacent areas. The locking anchors in the adjacent areas are 2.5m apart. The adjacent locking anchors in the adjacent areas are cross-set with opposite inclinations. The drilling length is 15 to 20m. The angle between each locking anchor extending into the surrounding area and the horizontal axis of the mountain can be 20° to 40°, so that the gravel area and the clay area form an overall stable support structure, which effectively prevents landslides and collapses of the mountain. After the anchor hole is drilled and grouting is carried out, including placing a grouting pipe in the borehole, the grouting pump injects cement slurry into the clay and gravel soil areas through the grouting pipe. The grouting pressure in the gravel soil area is 0.8~1.2MPa, and the grouting pressure in the clay area is 1~2.5MPa. After the grouting meets the design requirements, the anchor hole should be filled with mortar and HRB400 steel bars with a length of 15.24~20.24m and a diameter of 32mm should be inserted to form a locking anchor. The outer end of the locking anchor is exposed 12cm outside the excavated rock area or the sprayed concrete surface.

[0038] (c) Construction of system anchors 8 in clay and gravel areas: Each system anchor 8 is located in the middle and lower parts of each clay and gravel area. In the middle and lower parts of each clay and gravel area, based on the on-site construction conditions, ROC-D9 hydraulic drilling rig, YG-80 disc drill and multi-arm drill are used to drill holes for each system anchor. The anchor hole length is 9m, the hole diameter is 33mm, the downward inclination angle is 100, and the arrangement is in a plum blossom shape. The spacing between adjacent anchor holes is 2m. Grouting pipes are placed in the holes, and grouting pumps are used to inject grout into the clay and gravel through the grouting pipes. Cement slurry is poured into the gravel area, the grouting pressure in the gravel area is 0.8~1.2MPa, and the grouting pressure in the clay area is 1~2.5MPa. After the grouting meets the design requirements, the grouting pipe is pulled out, the anchor hole should be filled with mortar and HRB400 steel bars with a length of 9.24m and a diameter of 28mm are inserted to form a system anchor. The length of the rod inserted into the hole should not be less than 95% of the design length. The outer end of the system anchor is exposed 12cm outside the excavated rock surface or shotcrete surface to facilitate the hanging of the sprayed net and the anchoring of the net.

[0039] (d) Carry out mesh spraying concrete construction in clay and gravel areas: hang mesh on the exposed ends of system anchors and locking anchors in clay and gravel areas. The mesh size of the mesh spraying concrete layer is 20cm×20cm, and the mesh steel bar type is φ6mm. Then use a sprayer to spray the concrete layer on the mesh to form a mesh spraying concrete layer 9. The weight ratio of the spraying concrete is: cement: fine aggregate: coarse aggregate: water: accelerator: water reducer = 1:2.3:2.2:0.48:0.021:0.0075. Cement should be sulfate-resistant cement that meets national standards, and the cement strength grade should not be lower than P.O42.5. Fine aggregate (particle size less than 0.5mm) should be hard and durable coarse and medium sand, and the fineness modulus should be greater than 2.5. The moisture content during use should be controlled at 5% to 7%; coarse aggregate should be hard and durable pebbles or crushed stones, and the particle size should not be greater than 15mm.

[0040] The thickness of the mesh sprayed concrete layer is 12cm, the first layer is 4cm thick, the second and third layers are 4cm thick each, the outer end surface of the mesh sprayed concrete layer 9 is flush with the outer end surface of the rock area, the mesh sprayed concrete layer 9 should be cured, and a special person should carry out water spraying curing 2h after the final setting of the mesh sprayed concrete layer. The curing time shall not be less than 7 days and nights for general projects, and not less than 14 days and nights for important projects. When the temperature is below +5℃, water spraying curing is not allowed.

[0041] (e) Construction of prestressed anchor cables 16 in the clay and gravel areas: The prestressed anchor cables are located in the middle of the gravel area and the top of the clay area. Adjacent prestressed anchor cables are set at an interval of 6m. ROC-D9 hydraulic drilling rig, YG-80 disc drill and multi-arm drill are used to drill anchor holes 19. The anchor hole length is 40-50m, the hole diameter is 45mm, and the downward inclination angle is 10°. The anchor cable is made of Q235, 6×19 1000KN prestressed anchor cable, and the anchor cable diameter is 30-40mm. A grouting pipe is placed in the borehole, and a grouting pump injects cement slurry into the clay and gravel areas through the grouting pipe. The grouting uses cement slurry with a water-cement ratio of 1:1. The grouting pressure in the gravel area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting meets the design requirements, the grouting pipe is removed, the cable anchoring section in the anchor cable hole is grouted, and an anchor cable with a length of 40.3 to 50.3 m is inserted into the cable hole for cable threading construction 20. Then, a grouting expansion positioning stop ring is tied at the hole mouth, and the anchor pier concrete seat 21 is poured at the hole mouth, and the hole guide pipe and anchor pad are installed. When the bearing strength of the anchor pier concrete seat and the consolidation slurry reaches the construction requirements, the anchor cable is tensioned. The tensioning force increases step by step, and its maximum value is 1.05 to 1.1 times the design load of the anchor cable. It is locked after stabilizing the pressure for 10 to 20 minutes. Within 48 hours after locking, if the anchor cable stress drops to 10% below the design value, compensatory tensioning should be carried out. The hole sealing and backfilling grouting 22 is carried out 28 days after the completion of the compensatory tensioning work. Before the hole sealing and backfilling grouting 22, it should be confirmed that the anchor cable stress has reached the stable design value. After the grouting is completed, the steel strand bundle outside the anchor should be cut off except for 15cm. The end of the external anchor or steel strand bundle should be sealed and protected with concrete. The thickness of the concrete protection should not be less than 10cm.

[0042] (f) Locking anchors and anchor steel meshes are constructed for the rock area 1 of the same step. Each locking anchor is distributed in the rock area and around the intersection with the clay and gravel areas. In the rock area, ROC-D9 hydraulic drilling rigs, YG-80 disc drills, and multi-arm drills are used to drill holes for each locking anchor. The length of each locking anchor hole in the rock area is 12m, arranged in a plum blossom shape, and the spacing between adjacent locking anchor holes is 2m. After the anchor hole is grouted, the borehole should be filled with mortar and HRB400 steel bars with a length of 12.12m and a diameter of 32mm should be inserted to form a locking anchor. The construction of locking anchors in the rock area bordering the clay area and gravel area of ​​the same platform is as follows: the front part of the locking anchors in the intersecting area extends into the adjacent area, the locking anchors in the adjacent area are 2.5m apart, the drilling length is 15-20m, and after the anchor holes are drilled and grouting, the boreholes should be filled with mortar and HRB400 steel bars with a length of 15.12-20.12m and a diameter of 32mm should be inserted. The angle between the locking anchors extending into the surrounding areas and the horizontal axis of the mountain can be 20°~40° to form a locking anchor, and the outer end of the locking anchor is exposed 12cm outside the excavated rock area surface or the sprayed concrete surface, so that the gravel area and the clay area form an overall stable support structure, which effectively prevents landslides and collapses of the mountain.

[0043] An anchoring steel mesh is fixed on the end of the locking anchor rod on the outer end face of the protruding step rock area, and the anchoring steel mesh extends to cover the outer end face of the clay and gravel soil area in the same step step support surface and is fixed to the outer end head of the locking and system anchor rod corresponding to the end face of the mesh sprayed concrete layer exposed at the inner and outer ends of the area, forming an anchoring steel mesh layer covering the rock area, clay, and gravel soil area of ​​the same step step; (g) A sealing sprayed concrete layer 13 is applied on the anchoring steel mesh layer in the rock area, clay and gravel soil area of ​​the same step. The sealing sprayed concrete layer is 12 cm thick and is sprayed in three layers. The sealing sprayed concrete mix ratio is the same as the mesh sprayed concrete mix ratio. After curing, an ultra-high slope bank protection support with different soil layers on the same step is formed.

[0044] Embodiment 2 is different from Embodiment 1 in that: if there are cracks or loose rocks in the rock area of ​​the same step, a grouting pipe can be first placed in the locking anchor hole in the rock area, and a grouting pump injects cement slurry into the rock through the grouting pipe. The grouting pressure in the rock area is 1 to 1.5 MPa. After the grouting meets the design requirements, the anchor borehole should be filled with mortar and HRB400 steel bars with a length of 12.12 m and a diameter of 32 mm should be inserted. The length of the rod body inserted into the hole should not be less than 95% of the design length. The outer end of the locking anchor is exposed 12 cm outside the excavated rock area surface or the mesh sprayed concrete layer to form a locking anchor. The rest is the same as Embodiment 1, so it will not be repeated.

[0045] Embodiment 3 is different from Embodiment 1 in that: if there is no rock area in the construction surface of the same step, the outer end of the mesh sprayed concrete layer 9 is exposed in the clay and gravel soil area of ​​the same step construction surface, and the anchor steel mesh layer is fixed at the outer end of the system anchor rod to form an anchor steel mesh layer covering the clay and gravel soil area of ​​the same step, and then the sprayed concrete layer is sealed on the anchor steel mesh layer in the clay and gravel soil area of ​​the same step, and after maintenance, a super-high slope bank protection support of different soil layers of the same step is formed. The rest is the same as Embodiment 1, so it will not be repeated.

[0046] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A super-high slope bank protection structure and construction method suitable for different soil layers, characterized in that: The steps include: (1) Geological survey and support area division of super-high slopes: Conduct detailed geological survey of super-high slope revetments, including drilling sampling, soil layer analysis, and hydrogeological surveys, to determine the soil layer structure, type, and distribution of super-high slope revetments. Based on the physical and mechanical properties of the soil layer of the super-high slope revetments obtained from the survey, the slopes are divided into several support areas according to the soil layer conditions, stability, and water content. Each support area is divided into clay area, gravel area, and rock area according to the soil layer type. (2) Prepare construction equipment, tools, anchor rods and various raw materials; (3) Remove the backing layer of the super-high slope revetment, and excavate from top to bottom to form three steps of upper, middle and lower steps. Blasting, excavation and slag removal are carried out inward to the solid rock layer, clay layer or gravel layer. The horizontal excavation length of the upper step construction surface is at least 20m, the horizontal excavation length of the middle step construction surface is at least 17m, and the horizontal excavation length of the lower step construction surface is at least 14m. The angle between the construction surface of each step and the horizontal plane is less than 70°. (4) Design support schemes for each area based on geological survey and support area division of super-high slopes: (a) For clay areas, a support method combining locking anchors, system anchors, prestressed anchor cables, external mesh sprayed concrete layers and internal cement grouting is used; (b) For gravel soil areas, a support method combining locking anchors, system anchors, prestressed anchor cables, external mesh sprayed concrete layers and internal cement grouting is used; (c) Use a support method that combines anchor steel mesh and locking anchor rods in rock areas; (5) Connection between various regions: (a) The connection between the clay area and the rock area: the inner end of the locking anchor rod around the rock area extends into the adjacent clay area, and the surrounding area of ​​the anchor steel mesh in the rock area extends to cover the clay area; (b) The connection between the clay area and the gravel area: the peripheries of the mesh sprayed concrete layers in the clay area and the gravel area are connected to each other, cement grouting is carried out simultaneously in the clay area and the gravel area, the inner ends of the locking anchor rods around the gravel area extend into the clay area, and the inner ends of the locking anchor rods around the clay area extend into the gravel area; (c) The connection between the gravel soil area and the rock area: the inner ends of the locking anchor rods around the rock area extend into the gravel soil area, and the anchor steel mesh around the rock area extends to cover the gravel soil area; (d) The support construction of the same terrace surface is carried out in the clay area, gravel area and rock area in sequence; (6) The horizontal excavation length of each step construction surface should differ by at least 5m. The upper step construction should be carried out first. When the upper step construction surface reaches the designed construction surface, the upper step construction surface should be supported immediately. Then the middle step excavation should be carried out. When the middle step construction surface reaches the designed construction surface, the middle step construction surface should be supported immediately. Finally, the lower step excavation should be carried out. When the lower step construction surface reaches the designed construction surface, the lower step construction surface should be supported immediately. (7) The outer end surface of the clay and gravel soil area in each step support surface is recessed 12 cm from the outer end surface of the rock area. After support, the outer end surface of the mesh sprayed concrete layer at the outer end of the clay and gravel soil area in the same step support surface is flush with the outer end surface of the rock area in the same step, and the outer ends of the locking anchor rods and system anchor rods are exposed 12 cm outside the outer end surface of the mesh sprayed concrete layer; (8) After the locking anchor rod construction or locking anchor rod grouting construction is carried out on the same step rock area, the anchor steel mesh is fixed on the end of the locking anchor rod on the outer end face of the protruding step rock area, and the anchor steel mesh is extended to cover the outer end face of the clay and gravel soil area in the same step support surface and is fixed to the locking and system anchor rod outer end corresponding to the end face of the mesh sprayed concrete layer exposed at the inner and outer ends of the area, forming an anchor steel mesh layer covering the same step rock area, clay, and gravel soil area; (9) A sprayed concrete layer is placed on the anchored steel mesh layer in the rock area, clay, and gravel soil area of ​​the same step, and after curing, an ultra-high slope bank support with different soil layers on the same step is formed; (10) Construction at the intersection of each step construction surface: After the adjacent step support surface is completed, the construction at the intersection of the adjacent steps is carried out. A platform steel mesh is laid on the construction platform at the intersection of each step construction surface. The two ends of the platform steel mesh are respectively connected to the outer ends of the steel mesh on the upper and lower ends of the adjacent step construction surface. The overlap length of the two ends of the platform steel mesh when horizontally extended is 20 cm. Then, C25 concrete is poured or sprayed on the platform steel mesh to form a platform concrete layer. The thickness of the platform concrete layer is 20 cm. The two ends of the platform concrete layer are connected to the sealing and spraying concrete layers on the upper and lower ends of the adjacent step construction surface to complete the super-high slope bank protection support of different soil layers of each step.

2. The construction method according to claim 1, characterized in that: The thickness of the sealing sprayed concrete layer on the anchoring steel mesh layer is 12 cm.

3. The construction method according to claim 1, characterized in that: The mesh size of the anchoring steel mesh is 20cm×20cm, and the mesh steel bar model is φ8mm. The anchoring steel mesh is made by straightening and cutting the steel bars at the on-site processing camp, and then transporting them to the construction site for on-site binding and weaving into a mesh, which is laid from top to bottom. When docking, the overlap between the anchoring steel meshes is not less than 5cm, and they are tied with φ1.2mm iron wire at intervals of 1m.

4. The construction method according to claim 1, characterized in that: The mesh size of the platform steel mesh is 0.2m×0.2m, and the mesh steel bar model is φ12mm. To facilitate mesh installation, the platform steel mesh is first processed into a mesh sheet with a length and width of 100cm to 200cm.

5. The construction method according to claim 1, characterized in that: The support of each step construction surface includes: (a) Drainage holes are drilled in each area of ​​each step support surface: the drainage holes in the rock, clay, and gravel areas of each step support surface are 4 to 5 meters long, 56 mm in diameter, 8 degrees in elevation, arranged in a plum blossom shape, and 3 meters apart from each other. Bottom drainage holes are added to the bottom of the rock area of ​​each step support surface, with a length of 8 to 9 meters, a drainage hole diameter of 56 mm, an 8 degrees in elevation, arranged in a plum blossom shape, and 4 meters apart from each other; (b) Carry out locking anchor construction in clay and gravel areas: the outer end surface of the clay and gravel areas in each step support surface is recessed into the outer end surface of the rock area by 12 cm. Each locking anchor is located at the upper part of each clay and gravel area and the periphery of the intersection with the rock, clay and gravel areas. In the upper part of each clay and gravel area, based on the on-site construction conditions, ROC-D9 hydraulic drilling rig, YG-80 disc drill and multi-arm drill are used to drill holes for each anchor. The anchor hole length is 12 m, arranged in a plum blossom shape, and the spacing between adjacent anchor holes is 2. m, put the grouting pipe in the hole, and the grouting pump injects cement slurry into the clay and gravel soil areas through the grouting pipe. The grouting pressure in the gravel soil area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting meets the design requirements, the anchor hole should be filled with mortar and HRB400 steel bars with a length of 12.24m and a diameter of 32mm should be inserted to form a locking anchor. The length of the rod body inserted into the hole should not be less than 95% of the design length, and the outer end of the locking anchor should be exposed 12cm outside the excavated rock area surface or the mesh shotcrete layer; The locking anchors at the intersection with the rock, clay, and gravel areas shall be constructed such that the front of the locking anchors at the intersection extends into the adjacent area. The locking anchors in the adjacent area shall be 2.5m apart. The adjacent locking anchors in the adjacent area shall be arranged crosswise with opposite inclinations. The drilling length shall be 15-20m. After the anchor holes are drilled and grouted, the holes shall be filled with mortar and HRB400 steel bars with a length of 15.24-20.24m and a diameter of 32mm shall be inserted to form locking anchors. The outer ends of the locking anchors shall be exposed 12cm outside the excavated rock area or the sprayed concrete surface. (c) Carry out system anchor construction in clay and gravel areas: Each system anchor is located in the middle and lower parts of each clay and gravel area. In the middle and lower parts of each clay and gravel area, according to the on-site construction conditions, ROC-D9 hydraulic drilling rig, YG-80 disc drill and multi-arm drill are used to drill holes for each system anchor. The anchor hole length is 9m, the downward inclination angle is 10°, and it is arranged in a plum blossom shape. The spacing between adjacent anchor holes is 2m. Grouting pipes are placed in the holes, and the grouting pump passes through the grouting pipes. Pour cement slurry into the clay and gravel soil areas. The grouting pressure in the gravel soil area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting reaches the design requirements, the anchor hole should be filled with mortar and a 9.24m long HRB400 steel bar with a diameter of 28mm should be inserted to form a system anchor. The length of the rod inserted into the hole should not be less than 95% of the design length. The outer end of the system anchor is exposed 12cm outside the excavated rock surface or the sprayed concrete surface; (d) Carry out mesh spraying concrete construction in clay and gravel areas: hang mesh on the exposed ends of system anchors and locking anchors in clay and gravel areas, and then use a sprayer to spray concrete on the mesh to form a mesh spraying concrete layer. The thickness of the mesh spraying concrete layer is 12 cm, the first layer is 4 cm thick, and the second and third layers are each 4 cm thick. The outer end surface of the mesh spraying concrete layer is flush with the outer end surface of the rock area; (e) Construction of prestressed anchor cables in clay and gravel areas: The prestressed anchor cables are located in the middle of the gravel area and the top of the clay area. Adjacent prestressed anchor cables are set at an interval of 6m. The anchor cable drilling length is 40-50m and the downward inclination angle is 10°. The anchor cables are made of Q235, 6×19 1000KN prestressed anchor cables with a diameter of 30-40mm. Grouting pipes are placed in the boreholes. Grouting pumps inject cement slurry into the clay and gravel areas through the grouting pipes. The grouting pressure in the gravel area is 0.8-1.2MPa, and the grouting pressure in the clay area is 1-2.5MPa. After the grouting meets the design requirements, the grouting pipes are removed, and the cable body anchoring section is grouted in the cable hole. Anchor cables with a length of 40.3-50.3m are inserted into the cable holes, and then tied and filled with grout at the hole mouths. The expansion type positioning stop ring is used to cast the anchor pier concrete seat at the hole mouth, install the hole mouth guide pipe and anchor pad, and when the bearing strength of the anchor pier concrete seat and the consolidation slurry reaches the construction requirements, the anchor cable is tensioned. The tensioning force increases step by step, and its maximum value is 1.05-1.1 times the design load of the anchor cable. It is locked after stabilizing the pressure for 10-20 minutes. Within 48 hours after locking, if the anchor cable stress drops to 10% below the design value, compensation tensioning should be carried out. The sealing hole backfill grouting is carried out 28 days after the completion of the compensation tensioning work. Before the sealing hole backfill grouting, it should be confirmed that the anchor cable stress has reached the stable design value. After the grouting is completed, the steel strand bundle outside the anchor should be cut off except for 15cm. The end of the external anchor or steel strand bundle should be sealed and protected with concrete, and the thickness of the concrete protection should be not less than 10cm. (f) Locking anchors and anchor steel meshes are constructed in the rock area of ​​the same step. Each locking anchor is distributed in the rock area and around the intersection with the clay and gravel areas. In the rock area, ROC-D9 hydraulic drilling rigs, YG-80 disc drills, and multi-arm drills are used to drill holes for each locking anchor. The length of each locking anchor hole in the rock area is 12m, arranged in a plum blossom shape, and the spacing between adjacent locking anchor holes is 2m. After the anchor hole is grouted, the borehole should be filled with mortar and HRB400 steel bars with a length of 12.12m and a diameter of 32mm should be inserted to form a locking anchor. If there are cracks and looseness in the rock area of ​​the same step, a grouting pipe can be placed in the locking anchor hole first, and the grouting pump can inject cement slurry into the rock through the grouting pipe. The grouting pressure in the rock area is 1-1.5MPa. After the grouting meets the design requirements, the anchor hole should be filled with mortar and HRB400 steel bars with a length of 12.12m and a diameter of 32mm should be inserted. The length of the rod body inserted into the hole should not be less than 95% of the design length. The outer end of the locking anchor is exposed 12cm outside the excavated rock area surface or the mesh shotcrete layer to form a locking anchor. The locking anchor construction in the rock area bordering the clay area and gravel area of ​​the same platform is that the front part of the locking anchor in the intersecting area extends into the adjacent area. The locking anchors in the adjacent area are 2.5m apart and the drilling length is 15-20m. After the anchor hole is grouted, the borehole should be filled with mortar and HRB400 steel bars with a length of 15.12-20.12m and a diameter of 32mm should be inserted to form a locking anchor. The outer end of the locking anchor is exposed 12cm outside the excavated rock area surface or the sprayed concrete surface; An anchoring steel mesh is fixed on the end of the locking anchor rod on the outer end face of the protruding step rock area, and the anchoring steel mesh extends to cover the outer end face of the clay and gravel soil area in the same step step support surface and is fixed to the outer end head of the locking and system anchor rod corresponding to the end face of the mesh sprayed concrete layer exposed at the inner and outer ends of the area, forming an anchoring steel mesh layer covering the rock area, clay, and gravel soil area of ​​the same step step; (g) A sprayed concrete layer is placed on the anchored steel mesh layer in the rock area, clay and gravel soil area of ​​the same step, and after curing, an ultra-high slope bank support with different soil layers on the same step is formed.

6. The construction method according to claim 1, characterized in that: The grouting adopts cement slurry with a water-cement ratio of 1:

1.

7. The construction method according to claim 1, characterized in that: The construction of the locking anchor rod, the system anchor rod and the prestressed anchor cable is completed on the erected stepped scaffolding.

8. The construction method according to claim 1, characterized in that: The mesh size of the mesh sprayed concrete layer is 20cm×20cm, and the mesh steel bar model is φ6mm.

9. The construction method according to claim 1, characterized in that: The mixing weight ratio of the sprayed concrete is: cement: fine aggregate: coarse aggregate: water: accelerator: water reducer = 1:2.3:2.2:0.48:0.021:0.0075. The cement is sulfate-resistant cement that meets national standards, and the cement strength grade is not lower than P.O42.

5. The fine aggregate (particle size is less than 0.5mm) is hard and durable coarse and medium sand, and the fineness modulus is preferably greater than 2.

5. The moisture content during use is controlled at 5% to 7%; the coarse aggregate is hard and durable pebbles or crushed stones, and the particle size is not more than 15mm.

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