Combined supporting method for high and steep slope of mountain terrain

Abstract

The invention discloses a mountain terrain high and steep slope combined supporting method, and relates to the technical field of slope supporting, and the supporting method comprises the following steps: vertically and downwards constructing steel pipe piles from the slope top of a slope; geologic bodies, facing the outside of the slope, of the steel pipe piles are excavated in a layered mode, and a layer of anchor rods is constructed from the steel pipe piles to the inside of the slope every time the geologic bodies are excavated until the geologic bodies are excavated to a third elevation; leveling and hardening the ground at the third elevation to form a construction platform; a first underground diaphragm wall is constructed vertically downwards from the construction platform; vertically and upwards constructing a second underground diaphragm wall from the wall top of the first underground diaphragm wall; the wall top of the second underground diaphragm wall is not lower than the first elevation; and geologic bodies are backfilled between the second underground diaphragm wall and the steel pipe piles. By excavating the side slope and forming the construction platform, a construction site can be provided for large construction equipment under the condition that the site is limited, the geologic body is supported through the underground diaphragm wall structure and the steel pipe piles together, and the supporting stability of the side slope is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of slope protection technology, and in particular to a combined support method for steep slopes in mountainous terrain. Background Technology

[0002] In the process of urban development and construction, infrastructure construction is often required on original sites in sloping or even mountainous terrain. The steep slopes of mountainous terrain can typically reach tens of meters in height, and the support structure for such slopes requires high support capacity. Therefore, the support structure for steep slopes usually has a deep foundation, involving extensive deep foundation pit excavation during construction. However, due to limited construction space in mountainous terrain, large construction equipment is difficult to access, and manual excavation of deep foundation pits is time-consuming, labor-intensive, and carries high safety risks. Summary of the Invention

[0003] The main objective of this invention is to propose a combined support method for steep slopes in mountainous terrain, aiming to solve the technical problems of limited construction sites and difficulty in bringing large construction equipment into the site for the support structure of steep slopes in mountainous terrain in the prior art.

[0004] To achieve the above objectives, the present invention proposes a combined support method for steep mountain slopes, comprising the following steps: vertically constructing steel pipe piles from the top of the slope downwards; the top elevation of the steel pipe piles is a first elevation, and the bottom elevation of the steel pipe piles is a second elevation; excavating the geological body located outside the slope facing the steel pipe piles in layers, and constructing a layer of anchor bolts from the steel pipe piles inwards towards the slope for each layer of geological body excavated, until excavation reaches a third elevation; the third elevation is located between the first elevation and the second elevation; leveling and hardening the ground at the third elevation to form a construction platform; constructing a first diaphragm wall vertically downwards from the construction platform; constructing a second diaphragm wall vertically upwards from the top of the first diaphragm wall; the top of the second diaphragm wall is not lower than the first elevation; and backfilling the geological body between the second diaphragm wall and the steel pipe piles.

[0005] In one embodiment, the step of vertically constructing steel pipe piles from the top of the slope includes: drilling a hole vertically downward from the top of the slope to the second elevation; lowering a steel pipe into the hole so that the bottom end of the steel pipe reaches the second elevation; repeatedly injecting grout into the steel pipe under pressure until the grout overflows from the borehole located at the first elevation; and constructing a capping beam on top of the steel pipe to form the steel pipe pile.

[0006] In one embodiment, the step of excavating the geological body located outside the slope from the steel pipe pile in layers, and installing an anchor bolt from the steel pipe pile into the slope for each layer of the geological body being excavated, until the third elevation is reached, includes: excavating the geological body within a predetermined depth range outside the steel pipe pile, exposing the outer surface of the steel pipe pile; installing multiple anchor bolts spaced horizontally from the bottom of the outer surface of the steel pipe pile into the geological body in the slope; installing a horizontally arranged waist beam to connect the outer ends of the multiple anchor bolts; and returning to the step of excavating the geological body within a predetermined depth range outside the steel pipe pile, exposing the outer surface of the steel pipe pile, until the bottom of the outer surface of the steel pipe pile reaches the third elevation.

[0007] In one embodiment, the step of installing multiple horizontally spaced anchor rods from the bottom of the outer side of the steel pipe pile towards the geological body within the slope includes: drilling a hole from the bottom of the outer side of the steel pipe pile towards the inner side of the slope; lowering a rod with a grouting pipe installed into the hole; injecting grout into the hole through the grouting pipe to form an anchor body; after the anchor body reaches a preset strength, tensioning the rod body to form one anchor rod; and returning to the step of drilling a hole from the bottom of the outer side of the steel pipe pile towards the inner side of the slope, so that the multiple holes are distributed horizontally at intervals until multiple anchor rods are formed.

[0008] In one embodiment, the step of injecting grout into the borehole through the grouting pipe to form an anchor body includes: injecting M30 cement grout into the borehole through the grouting pipe at a grouting pressure of 0.8 MPa; and after the M30 cement grout has initially set, injecting pure cement grout with a water-cement ratio of 0.5 into the borehole through the grouting pipe at a grouting pressure of 2 MPa.

[0009] In one embodiment, the step of backfilling the geological body between the second diaphragm wall and the steel pipe pile includes: backfilling a layer of geological body between the second diaphragm wall and the steel pipe pile, such that the top surface of the geological body is 50mm below the lowest layer of the waist beam; pouring a layer of plain concrete on the top surface of the geological body; removing the lowest layer of the waist beam and one layer of the anchor rods; and returning to the step of backfilling a layer of geological body between the second diaphragm wall and the steel pipe pile, such that the top surface of the geological body is 50mm below the lowest layer of the waist beam, until the top surface of the geological body reaches the first elevation.

[0010] In one embodiment, the step of constructing the first diaphragm wall vertically downward from the construction platform includes: constructing a guide wall on the construction platform along the designed position of the first diaphragm wall; excavating a trench downward along the guide wall using trenching equipment; placing a reinforcing cage in the excavated trench; and pouring underwater concrete through a tremie pipe to form the first diaphragm wall.

[0011] In one embodiment, the step of constructing a second diaphragm wall vertically upward from the top of the first diaphragm wall includes: removing the laitance at the top of the first diaphragm wall and treating the joint surface; erecting a construction scaffold at the top of the first diaphragm wall; binding reinforcing bars and setting up formwork at the top of the first diaphragm wall; and pouring concrete through the formwork to form a second diaphragm wall connected to the first diaphragm wall.

[0012] In one embodiment, the step of excavating a trench downward along the guide wall using a trenching device includes: drilling multiple guide holes downward from the construction platform using a rotary drilling rig; grabbing the soil within the range of the multiple guide holes using a trenching machine; and milling the rock within the range of the multiple guide holes using a trench milling machine to form the trench.

[0013] In one embodiment, after the step of vertically driving steel pipe piles downward from the top of the slope, the method further includes the step of constructing a drainage ditch on the side of the top of the steel pipe piles near the inside of the slope.

[0014] The proposed method for combined support of steep mountain slopes utilizes steel pipe piles installed within the slope and multiple layers of anchor bolts during slope excavation. The steel pipe piles and anchor bolts together form a temporary support structure, providing lateral support to the geological mass on the inner side of the slope and ensuring the safe installation of the construction platform. By excavating the geological mass on the outer side of the slope and forming a construction platform, a construction site can be provided for large construction equipment in mountainous terrain with limited space, facilitating subsequent construction of the first and second diaphragm walls without the need for manual excavation of deep foundation pits, saving time and labor. The first diaphragm wall is embedded in the geological mass below the construction platform, and the second diaphragm wall is continuously installed above the first diaphragm wall. Together, they form a diaphragm wall structure, giving the diaphragm wall sufficient depth to serve as a permanent support structure for the slope. After backfilling the geological mass between the second diaphragm wall and the steel pipe piles, the diaphragm wall structure can provide lateral support to the outside of the backfilled geological mass, while the steel pipe piles can provide lateral support to the inside of the backfilled geological mass. This allows the diaphragm wall structure and the steel pipe piles to jointly provide stable support to the backfilled geological mass, effectively improving the slope's support stability. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of an embodiment of the support structure in the mountainous terrain steep slope support method provided by the present invention. Figure 2 This is a flowchart illustrating an embodiment of the mountainous terrain steep slope support method provided by the present invention.

[0017] Explanation of icon numbers: 10. Steel pipe piles; 20. Anchor bolts; 30. Construction platform; 40. First diaphragm wall; 50. Second diaphragm wall; 60. Interception ditch.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] In the process of urban development and construction, infrastructure construction is often required on original sites in sloping or even mountainous terrain. The steep slopes of mountainous terrain can typically reach tens of meters in height, and the support structure for such slopes requires high support capacity. Therefore, the support structure for steep slopes usually has a deep foundation, involving extensive deep foundation pit excavation during construction. However, due to limited construction space in mountainous terrain, large construction equipment is difficult to access, and manual excavation of deep foundation pits is time-consuming, labor-intensive, and carries high safety risks.

[0023] This invention proposes a combined support method for steep slopes in mountainous terrain, comprising the following steps: S10: Steel pipe piles are constructed vertically downwards from the top of the slope; the top elevation of the steel pipe piles is the first elevation, and the bottom elevation of the steel pipe piles is the second elevation; As a sloping structure in mountainous terrain, the slope is constructed by vertically driving steel pipe piles 10 from the top of the slope downwards, so that the steel pipe piles 10 extend into the geological body of the slope and divide the slope into inner and outer sides. The steel pipe piles 10 can pre-form a vertical support structure inside the slope, providing initial support for subsequent excavation and preventing the slope from sliding or collapsing in the initial stage.

[0024] S20: Layered excavation of the geological body located outside the slope from the steel pipe piles. For each layer of the geological body excavated, an anchor bolt is installed from the steel pipe piles into the slope until the third elevation is reached; the third elevation is located between the first and second elevations. After the steel pipe piles 10 are installed, they provide support to the geological body inside the piles. The geological body outside the piles is excavated in layers until the third elevation is reached, exposing the portion of the piles 10 between the first and third elevations, while the portion between the second and third elevations is embedded within the geological body, ensuring sufficient lateral support capacity. During the layered excavation, anchor bolts 20 are installed layer by layer to gradually release slope stress. The anchor bolts 20 are installed from the steel pipe piles 10 inwards into the slope, enhancing the rock and soil anchoring force in the excavation area, controlling slope deformation, and ensuring local stability during the excavation process.

[0025] S30: Level and harden the ground at the third elevation to form a construction platform; After the slope is excavated to the third elevation, a certain construction space is formed outside the steel pipe piles 10. After the ground of this construction space is leveled and hardened, a construction platform 30 is formed. The construction platform 30 is the boundary elevation between the first diaphragm wall 40 and the second diaphragm wall 50. The construction platform 30 can accommodate large construction equipment and provides a construction site for the subsequent construction of the first diaphragm wall 40 and the second diaphragm wall 50.

[0026] S40: Construct the first underground diaphragm wall vertically downwards from the construction platform; The first underground continuous wall 40 is constructed vertically downward from the construction platform 30, which can form a retaining and seepage prevention structure at the bottom of the slope, enhance the overall stability of the bottom of the slope, and prevent the soil below from sliding or seeping during subsequent construction.

[0027] S50: Construct a second diaphragm wall vertically upward from the top of the first diaphragm wall; the top of the second diaphragm wall shall not be lower than the first elevation; The first diaphragm wall 40 is embedded in the geological body below the construction platform 30. After the first diaphragm wall 40 is formed, the second diaphragm wall is constructed upward along the top of the first diaphragm wall 40, so that the first diaphragm wall 40 continues to extend upward. The lengths of the first diaphragm wall 40 and the second diaphragm wall are the same, forming a continuous diaphragm wall structure.

[0028] S60: Backfill the geological mass between the second diaphragm wall and the steel pipe pile.

[0029] The diaphragm wall structure and the steel pipe piles 10 are spaced apart. The area between the diaphragm wall and the steel pipe piles 10 is the geological body excavated in step S20, located outside the slope facing the steel pipe piles 10. After the diaphragm wall structure is formed, the geological body is backfilled between the diaphragm wall and the steel pipe piles 10, so that the top surface of the geological body reaches the first elevation. The diaphragm wall structure provides lateral support to the outside of the backfilled geological body, and the steel pipe piles 10 provide lateral support to the inside of the backfilled geological body. Together, they maintain the stability of the backfilled geological body.

[0030] The proposed method for combined support of steep mountain slopes utilizes steel pipe piles 10 installed within the slope and multiple layers of anchor bolts 20 installed during slope excavation. The steel pipe piles 10 and anchor bolts 20 together form a temporary support structure, providing lateral support to the geological body on the inner side of the slope and ensuring the safe installation of the construction platform 30. By excavating the geological body on the outer side of the slope and forming the construction platform 30, a construction site can be provided for large construction equipment in mountainous terrain with limited space, facilitating subsequent construction of the first diaphragm wall 40 and the second diaphragm wall 50 without the need for manual excavation of deep foundation pits, saving time and labor. The first diaphragm wall 40 is embedded in the geological body below the construction platform 30, and the second diaphragm wall 50 is continuously set above the first diaphragm wall 40. Together, they form a diaphragm wall structure, which has sufficient burial depth to serve as a permanent support structure for the slope. After the geological body is backfilled between the second diaphragm wall 50 and the steel pipe piles 10, the diaphragm wall structure can provide lateral support to the outside of the backfilled geological body, and the steel pipe piles 10 can provide lateral support to the inside of the backfilled geological body. Thus, the diaphragm wall structure and the steel pipe piles 10 together provide stable support to the backfilled geological body, effectively improving the support stability of the slope.

[0031] In one embodiment, step S10 includes: S11: Drill a hole vertically downwards from the top of the slope to the second elevation; S12: Lower the steel pipe into the hole so that the bottom end of the steel pipe reaches the second elevation; S13: Apply pressure to the steel pipe and inject grout multiple times until the grout overflows from the borehole at the first elevation. S14: Construct a capping beam at the top of the steel pipe to form the steel pipe pile.

[0032] Understandably, drilling a hole vertically downwards from the top of the slope to the second elevation provides accurate space for lowering the steel pipe; lowering the steel pipe into the hole ensures its bottom end reaches the second elevation, guaranteeing the pipe's position matches the design elevation; multiple pressurized grouting injections are performed into the steel pipe until grout overflows from the borehole at the first elevation, filling the gap between the steel pipe and the hole, reinforcing the connection between the steel pipe and the surrounding geological body, and improving the bearing capacity and pull-out resistance of the steel pipe pile 10; a capping beam is constructed at the top of the steel pipe, connecting the tops of multiple steel pipe piles 10 to form an integral structure, enhancing the top stability and collaborative working ability of the steel pipe piles 10. This effectively ensures the construction accuracy and structural integrity of the steel pipe piles 10, enabling them to provide reliable lateral support to the geological body on the inner side of the slope, enhancing the stability of the temporary support structure, and thus working together with the anchor bolts 20 and the diaphragm wall to improve the overall performance and durability of the entire support system.

[0033] In one embodiment, step S20 includes: S21: Excavate the geological body within a predetermined depth range outside the steel pipe pile, so that the outer surface of the steel pipe pile is exposed. S22: Install multiple horizontally spaced anchor bolts from the bottom of the outer side of the steel pipe pile toward the geological body in the slope; S23: Construct a horizontally arranged waist beam to connect the outer ends of the plurality of anchor rods; S24: Return to the step of excavating the geological body located at a preset depth outside the steel pipe pile, exposing the outer surface of the steel pipe pile, until the bottom of the outer surface of the steel pipe pile reaches the third elevation.

[0034] Understandably, by excavating the geological body within a predetermined depth outside the steel pipe pile 10, the outer surface of the steel pipe pile 10 is exposed, providing a working surface for the installation of anchor bolts 20. Multiple anchor bolts 20 are installed horizontally at intervals from the bottom of the outer surface of the steel pipe pile 10 towards the geological body inside the slope. The anchor bolts 20 are driven horizontally into the geological body inside the slope, providing anchoring force to balance the external soil pressure. A horizontally installed wainscoting is then installed, connecting the outer ends of the multiple anchor bolts 20, allowing the dispersed anchor bolts 20 to work together to form a support strip. The above steps are repeated until multiple support strips are formed. The layered multiple support strips ensure timely, layered, and continuous lateral reinforcement of the geological body outside the slope during excavation. The support structure formed by the anchor bolts 20 and the wainscoting effectively constrains the deformation of the soil outside the slope, enhancing the integrity and stability of the temporary support system together with the steel pipe pile 10. This safely forms the construction platform 30 during excavation to the third elevation and provides stable working conditions for the subsequent construction of the diaphragm wall.

[0035] In one embodiment, step S22 includes: S221: Drill a hole from the bottom of the outer side of the steel pipe pile toward the inner side of the slope; S222: Lower the rod with the grouting pipe installed into the hole; S223: Grout is injected into the hole through the grouting pipe to form an anchor body; S224: After the anchor body reaches the preset strength, the rod body is tensioned to form an anchor rod; S225: Return to the step of drilling a hole from the bottom of the outer side of the steel pipe pile to the inner side of the slope, so that multiple holes are distributed at intervals in the horizontal direction until multiple anchor rods are formed.

[0036] It should be noted that a hole is drilled from the bottom of the outer side of the steel pipe pile 10 towards the inner side of the slope to provide precise positioning and anchoring space for the anchor rod 20. The rod body with the grouting pipe installed is lowered into the hole. The rod body acts as a force transmission component, and the grouting pipe is used for subsequent grouting. Grout is injected into the hole through the grouting pipe. The grout solidifies in the hole to form an anchor body. The anchor body wraps around the rod body and is tightly bonded to the surrounding geological body. After the anchor body reaches the preset strength, the rod body is tensioned to generate prestress in the anchoring section, forming an anchor rod 20 with a predetermined anchoring force. The above steps are repeated until multiple anchor rods 20 are formed, ensuring that each anchor rod 20 can achieve the designed anchoring performance and bearing capacity. After multiple anchor rods 20 distributed horizontally are connected by a waist beam, they can provide uniform and reliable lateral anchoring force to the geological body on the outer side of the slope during the layered excavation process, enhance the constraint capacity of the temporary support system on soil deformation, and thus improve the construction safety and overall stability of the combined support method for steep mountain slopes.

[0037] In one embodiment, step S223 includes: S2231: M30 cement grout is injected into the hole through the grouting pipe at a grouting pressure of 0.8 MPa; S2232: After the M30 cement grout has initially set, pure cement grout with a water-cement ratio of 0.5 is injected into the hole through the grouting pipe at a grouting pressure of 2MPa.

[0038] Furthermore, the M30 cement grout, injected under relatively low pressure, can initially fill the borehole space and penetrate the surrounding geological body. After the M30 cement grout has initially set, pure cement grout with a water-cement ratio of 0.5 is injected into the same borehole through the grouting pipe at a grouting pressure of 2 MPa. The initially set M30 cement grout provides a sealing foundation for subsequent high-pressure grouting. The higher grouting pressure of 2 MPa and the pure cement grout with a water-cement ratio of 0.5 can compact and replenish the initially filled grout, squeezing out any voids or shrinkage cracks that may exist in the M30 cement grout. By adopting a process of injecting grout with different proportions in stages, starting with low pressure and then high pressure, it can ensure that the formed anchor body is dense, full, and in close contact with the borehole wall, thereby improving the structural strength of the anchor body itself and its adhesion to the surrounding geological body. This allows the anchor rod 20 to ultimately achieve higher anchoring performance and long-term durability, thereby improving the overall bearing reliability of the temporary support system composed of the anchor rod 20, the waist beam, and the steel pipe pile 10, and enhancing the support effect on steep slopes.

[0039] In one embodiment, step S60 includes: S61: Backfill a layer of geological body between the second underground continuous wall and the steel pipe pile, so that the top surface of the geological body is located 50mm below the lowest waist beam; S62: Pour a layer of plain concrete on the top surface of the geological body; S63: Remove the lowest layer of the waist beam and the first layer of the anchor bolts; S64: Return to the step of backfilling a layer of geological body between the second underground continuous wall and the steel pipe pile, so that the top surface of the geological body is located 50mm below the lowest waist beam, until the top surface of the geological body reaches the first elevation.

[0040] Understandably, when backfilling the geological mass between the diaphragm wall structure and the steel pipe piles 10, a layered backfilling method is adopted. First, a layer of geological mass is backfilled to 50mm below the lowest lintel, reserving space for subsequent lintel operations. Then, a layer of plain concrete is poured on top of the geological mass, forming a horizontal rigid cover after hardening. Next, the lowest lintel above this plain concrete layer and the anchor bolts 20 connected to it are removed. Then, the process of backfilling a new layer of geological mass to 50mm below the new lowest lintel is repeated, along with the pouring of the plain concrete layer and the removal of the previous lintel and anchor bolts 20, continuing in a cycle until the top surface of the backfilled geological mass reaches the first elevation. After each layer of backfilling and plain concrete pouring is completed, the corresponding temporary support components are promptly removed. The backfilling process of the geological body is synchronized and alternated with the removal of the temporary support structure. The plain concrete layer forms a hardened layer on top of each backfill layer, which can effectively transfer and disperse the upper load and restrain the lateral deformation of the backfill. By removing the waist beam and anchor rod 20 layer by layer from bottom to top, it is ensured that the hardened plain concrete layer below, the lateral second underground continuous wall 50 and the steel pipe pile 10 provide support throughout the process of the backfill gradually increasing in height and the permanent support structure gradually forming. This ensures the compactness and stability of the backfill geological body while safely and orderly removing the temporary support structure, and ultimately enables the underground continuous wall structure and steel pipe pile 10 to form a reliable and permanent joint support for the complete backfill.

[0041] In one embodiment, step S40 includes: S41: Construct a guide wall on the construction platform along the designed position of the first underground continuous wall; S42: Use trenching equipment to excavate a trench downwards along the guide wall; S43: Hang the steel reinforcement cage into the excavated trench; S44: Underwater concrete is poured through a conduit to form the first underground continuous wall.

[0042] It can be explained that by constructing a guide wall on the construction platform 30 along the designed position of the first diaphragm wall 40, the guide wall provides precise guidance and benchmark for subsequent trenching operations, and can protect the trench opening and prevent collapse; using trenching equipment to excavate the trench downwards along the guide wall, the trenching equipment excavates a continuous trench that meets the design depth and width under the guidance of the guide wall; a steel cage is hoisted into the excavated trench, and the steel cage is placed in the trench as the load-bearing skeleton of the diaphragm wall; underwater concrete is poured through a tremie pipe, and the concrete fills the trench from bottom to top through the tremie pipe, wrapping and solidifying the steel cage, finally forming the first diaphragm wall 40. The guide wall ensures the accuracy of the trench excavation and the temporary stability of the trench wall. Mechanized trenching ensures construction efficiency and the regularity of the trench shape. The placement of the steel cage provides the wall with bending and shear resistance. The underwater casting process ensures the compactness and continuity of the concrete in the deep trench environment. Together, these factors ensure that the first diaphragm wall 40 has an accurate planar position, sufficient structural strength, and good integrity, making it an important component of the permanent support structure buried under the construction platform 30. Together with the second diaphragm wall 50 constructed subsequently, it forms a complete and reliable diaphragm wall structure.

[0043] In one embodiment, step S50 includes: S51: Remove the laitance at the top of the first underground continuous wall and treat the joint surface; S52: Erect a construction scaffold on top of the first underground continuous wall; S53: Tie reinforcing bars at the top of the first diaphragm wall and erect formwork; S54: Concrete is poured through the template to form a second diaphragm wall connected to the first diaphragm wall.

[0044] It should be noted that, in order to ensure the connection strength between the first diaphragm wall 40 and the second diaphragm wall 50, the laitance on the top of the first diaphragm wall 40 is removed and the joint surface is treated to remove the loose surface layer and form a clean, rough bonding surface. A construction scaffold is erected on the top of the first diaphragm wall 40 to provide a safe and stable working platform for subsequent rebar tying, formwork erection and concrete pouring. Rebar is tied and formwork is erected on the top of the treated first diaphragm wall 40. The rebar forms the load-bearing skeleton of the second diaphragm wall 50, and the formwork defines the geometry and size of the wall. Concrete is poured through the formwork, and the concrete combines with and solidifies with the treated surface on the top of the first diaphragm wall 40 to form the second diaphragm wall 50 connected to the first diaphragm wall 40. The construction ensured reliable bonding and effective force transfer of the concrete at the contact surface between the first diaphragm wall 40 and the second diaphragm wall 50. The construction scaffold ensured the safety and convenience of high-altitude operations. The reinforcing steel reinforcement gave the wall the designed structural strength. The formwork ensured the verticality and cross-sectional dimensions of the wall. Finally, the second diaphragm wall 50 and the first diaphragm wall 40 below were structurally continuous and completely integrated into a whole, forming a diaphragm wall structure with sufficient height and integrity.

[0045] In one embodiment, step S42 includes: S421: Use a rotary drilling rig to drill multiple pilot holes downward from the construction platform; S422: Use a trenching machine to grab the soil within the range of the multiple guide holes; S423: Use a milling machine to mill the rock mass within the range of the multiple guide holes to form the channel.

[0046] Understandably, the excavation and trenching of deep foundation pits are carried out through a combination of rotary drilling rigs, trenching machines, and milling machines. The rotary drilling rig drills multiple guide holes downward from the construction platform 30. These guide holes are pre-drilled in hard or complex strata to provide positioning and entry guidance for subsequent equipment. The trenching machine grabs the soil within the range of the multiple guide holes and performs efficient excavation. The milling machine mills the rock within the range of the multiple guide holes, using milling wheels to cut and break up hard rock layers, ultimately forming the trench. In response to the complex geological conditions of steep mountain slopes, often characterized by alternating soil and rock layers or hard rock strata, a combination of rotary drilling rigs, trenching machines, and milling machines was employed. The pre-drilled guide holes of the rotary drilling rig improved the positioning accuracy of subsequent trenching operations and reduced the initial entry difficulty of the equipment in hard rock strata. The trenching machine and milling machine were used to specifically handle the soil and rock masses, respectively, giving full play to the advantages of different machines and overcoming the limitations of single equipment in complex geological conditions. This ensured that continuous trenches with regular shapes and accurate dimensions could be excavated efficiently and accurately under various geological conditions, laying the foundation for subsequent placement of steel cages and pouring of concrete. This ensured that the final first diaphragm wall 40 had uniform verticality, good continuity, and reliable load-bearing capacity.

[0047] In one embodiment, after step S10, the combined support method for steep slopes in mountainous terrain proposed in this invention further includes the following steps: S101: Construct a drainage ditch on the side of the slope near the top of the steel pipe pile.

[0048] Explained, before excavating the geological body on the outer side of the slope, a water interception ditch 60 is constructed on the top of the steel pipe pile 10 near the inner side of the slope. The water interception ditch 60 serves as a surface drainage facility, forming a flow interception barrier in the slope top area. It can intercept and divert surface water flowing from higher points on the inner side of the slope, preventing surface water from overflowing into the area of ​​the steel pipe pile 10 and the free face of the slope formed by subsequent excavation. This provides a drier and more stable working environment for subsequent layered excavation, anchor bolt 20 installation, construction platform 30 formation, and diaphragm wall construction, reducing the risk of slope instability caused by water and enhancing the safety of the entire combined support method construction process and the long-term reliability of the final support structure.

[0049] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of protection of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.

Claims

1. A method for combined support of steep slopes in mountainous terrain, characterized in that, Including the following steps: Steel pipe piles are constructed vertically downwards from the top of the slope; the top elevation of the steel pipe piles is the first elevation, and the bottom elevation of the steel pipe piles is the second elevation. The geological body located outside the slope from the steel pipe piles is excavated in layers. For each layer of the geological body excavated, an anchor bolt is installed from the steel pipe piles into the slope until the excavation reaches the third elevation; the third elevation is located between the first elevation and the second elevation. Level and harden the ground at the third elevation to form a construction platform; The first diaphragm wall is constructed vertically downwards from the construction platform; A second diaphragm wall is constructed vertically upwards from the top of the first diaphragm wall; the top of the second diaphragm wall is not lower than the first elevation. Backfill the geological mass between the second diaphragm wall and the steel pipe pile.

2. The method for combined support of steep slopes in mountainous terrain as described in claim 1, characterized in that, The step of vertically driving steel pipe piles from the top of the slope downwards includes: A hole is drilled vertically downwards from the top of the slope to the second elevation; Lower the steel pipe into the hole so that the bottom end of the steel pipe reaches the second elevation; The steel pipe is pressurized and grouted multiple times until the grout overflows from the borehole at the first elevation. A capping beam is constructed on top of the steel pipe to form the steel pipe pile.

3. The method for combined support of steep slopes in mountainous terrain as described in claim 1, characterized in that, The step of excavating in layers within the geological body facing outwards from the slope, and installing one anchor bolt from the steel pipe piles inwards towards the slope for each layer of the geological body being excavated, until the third elevation is reached, includes: Excavate the geological body within a predetermined depth range outside the steel pipe pile, so that the outer surface of the steel pipe pile is exposed; Multiple horizontally spaced anchor bolts are installed from the bottom of the outer side of the steel pipe pile toward the geological body within the slope. A horizontally positioned waist beam is constructed, through which the outer ends of the plurality of anchor rods are connected; Return to the step of excavating the geological body located at a preset depth outside the steel pipe pile, exposing the outer surface of the steel pipe pile, until the bottom of the outer surface of the steel pipe pile reaches the third elevation.

4. The method for combined support of steep slopes in mountainous terrain as described in claim 3, characterized in that, The step of installing multiple horizontally spaced anchor bolts from the bottom of the outer side of the steel pipe pile toward the geological body within the slope includes: Drill a hole from the bottom of the outer side of the steel pipe pile toward the inner side of the slope; The rod with the grouting pipe installed is lowered into the hole; Grout is injected into the hole through the grouting pipe to form an anchor body; Once the anchor body reaches the preset strength, the rod is tensioned to form the anchor rod. Return to the step of drilling a hole from the bottom of the outer side of the steel pipe pile toward the inner side of the slope, so that multiple holes are distributed at intervals in the horizontal direction until multiple anchor rods are formed.

5. The method for combined support of steep slopes in mountainous terrain as described in claim 4, characterized in that, The step of injecting grout into the borehole through the grouting pipe to form an anchor body includes: M30 cement grout is injected into the borehole through the grouting pipe at a grouting pressure of 0.8 MPa; After the M30 cement grout has initially set, pure cement grout with a water-cement ratio of 0.5 is injected into the hole through the grouting pipe at a grouting pressure of 2 MPa.

6. The method for combined support of steep slopes in mountainous terrain as described in claim 3, characterized in that, The step of backfilling the geological body between the second diaphragm wall and the steel pipe pile includes: A layer of geological material is backfilled between the second underground continuous wall and the steel pipe pile, so that the top surface of the geological material is located 50mm below the lowest waist beam. A layer of plain concrete was poured on the top surface of the geological body. Remove the lowest layer of the waist beam and the first layer of the anchor bolts; Return to the step of backfilling a layer of geological material between the second diaphragm wall and the steel pipe pile, so that the top surface of the geological material is located 50mm below the lowest waist beam, until the top surface of the geological material reaches the first elevation.

7. The method for combined support of steep slopes in mountainous terrain as described in any one of claims 1 to 6, characterized in that, The steps of constructing the first diaphragm wall vertically downwards from the construction platform include: A guide wall is constructed on the construction platform along the designed position of the first diaphragm wall; Use trenching equipment to excavate a trench downwards along the guide wall; A steel reinforcement cage is suspended inside the excavated trench; The first underground continuous wall is formed by underwater concrete pouring through a conduit.

8. The method for combined support of steep slopes in mountainous terrain as described in claim 7, characterized in that, The step of constructing the second diaphragm wall vertically upward from the top of the first diaphragm wall includes: Remove the laitance at the top of the first diaphragm wall and treat the joint surface; A construction scaffold was erected on top of the first underground continuous wall; Reinforcing bars were tied to the top of the first diaphragm wall and formwork was erected. Concrete is poured through the template to form a second diaphragm wall that is connected to the first diaphragm wall.

9. The method for combined support of steep slopes in mountainous terrain as described in claim 7, characterized in that, The step of excavating a trench downward along the guide wall using trenching equipment includes: Multiple pilot holes were drilled downwards from the construction platform using a rotary drilling rig. The trenching machine is used to grab the soil within the range of the multiple guide holes; The rock mass within the range of the multiple guide holes is milled using a milling machine to form the channel.

10. The method for combined support of steep slopes in mountainous terrain as described in any one of claims 1 to 6, characterized in that, After the step of vertically driving steel pipe piles downwards from the top of the slope, the method further includes the step of: A drainage ditch is constructed on the top of the steel pipe pile, on the side closest to the inside of the slope.

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