Anti-skid space unit, anti-skid structure and construction method thereof

Abstract

The application discloses an anti-sliding space unit, an anti-sliding structure and a construction method thereof, and relates to the technical field of landslide support construction. The anti-sliding space unit comprises a plurality of bored piles arranged according to polygon vertexes and a plurality of driven piles arranged between adjacent bored piles at a preset interval, and the two together form a closed edge frame to form a high-moment-of-inertia composite component. The bored piles on the side of the landslide body are provided with prestressed anchor cables. The closed edge frame is internally provided with a cross-type internal support, which is rigidly connected with the edge frame pile body to form a triangular stable stress structure. The bottom of the bored pile and the driven pile is embedded into bedrock, and a steel reinforcement densification area is arranged at the connection position. The high moment of inertia of the closed edge frame improves the bending stiffness, the anchor cable is resistant to tension, the internal support is resistant to shearing, and the bottom of the pile is resistant to shearing, so that a multi-stage collaborative stress system is formed, and the problems of weak bending resistance of the existing anti-sliding structure, lateral instability of the edge frame and insufficient shearing resistance at the bottom of the pile are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of landslide support construction technology, and in particular to an anti-slide spatial unit, an anti-slide structure, and a construction method thereof. Background Technology

[0002] Landslides are a common geological hazard that poses a serious threat to highways, railways, urban buildings, and the surrounding ecological environment, even causing casualties and property damage. Currently, commonly used anti-slide structures in landslide control projects mainly include single anti-slide piles, lattice beams, and anti-slide retaining walls. However, existing technologies have the following shortcomings: Insufficient bending stiffness: Single rotary drilling piles or rotary drilling piles that rely on a single pile to bear landslide thrust have small moments of inertia and weak resistance to bending deformation, making them difficult to cope with landslide conditions with high thrust and large bending moment.

[0003] The stress distribution mode is singular and lacks coordination: conventional anti-slide piles are not paired with anchor cables to coordinate the stress distribution, and the horizontal thrust is entirely borne by the pile body, resulting in large bending moments and high deformation risks; although lattice beams can cover a large area, they lack effective pile body coordination support, resulting in insufficient overall stiffness and easy structural damage caused by uneven local stress distribution.

[0004] The frame structure is prone to lateral instability: Most existing anti-slide piles have an open frame design without internal reinforcement support. Under the action of lateral earth pressure, the frame is prone to lateral instability, which affects the overall stability.

[0005] The shear resistance of the connection between the pile bottom and the bedrock is weak: the traditional deep-buried pile bottom process is difficult to construct, has a long cycle, causes great disturbance to the bedrock, and does not have a targeted shear-strengthening structure. Shear failure is prone to occur at the pile bottom connection, and excessive burial depth further increases costs.

[0006] Therefore, there is an urgent need for a landslide control structure that can improve the overall bending stiffness, instability resistance, and pile bottom shear performance through component collaboration and structural optimization.

[0007] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0008] The purpose of this invention is to provide an anti-slip spatial unit, an anti-slip structure, and a construction method thereof to solve the problems existing in the prior art. By combining components and optimizing the structure, the overall bending stiffness, instability resistance, and shear resistance of the pile bottom are improved.

[0009] To achieve the above objectives, the present invention provides the following solution: An anti-slide spatial unit is characterized by comprising multiple rotary drilling piles arranged at the vertices of a polygon, and several driven piles arranged at preset intervals between adjacent rotary drilling piles. The rotary drilling piles and driven piles together form a closed frame, creating a composite component with a high moment of inertia. The rotary drilling piles on the side adjacent to the landslide body are provided with prestressed anchor cables. The closed frame is provided with cross-type internal supports, the two ends of which are rigidly connected to the frame piles, forming a triangular stable force-bearing structure with the closed frame. The bottoms of the rotary drilling piles and driven piles are embedded in bedrock, and a reinforced steel reinforcement zone is provided at the connection between the pile bottom and the bedrock.

[0010] In one exemplary embodiment, the polygon is rectangular, and there are four rotary drilling piles arranged at the vertices of the quadrilateral.

[0011] In an exemplary embodiment, the moment of inertia of the composite member is calculated and determined according to the following formula: ； ； In the formula: Let be the moment of inertia of the composite component about the horizontal axis; Let be the moment of inertia of the composite component about the vertical axis; B is the horizontal side length of the composite component; H is the vertical side length of the composite component; b is the equivalent thickness of the border post; The equivalent thickness b is calculated using a weighted average method: ； In the formula: The diameter of the rotary drilling pile; This refers to the number of rotary drilling piles on a single side; The diameter of the driven pile; This refers to the number of stakes driven into a single side. L is the length of a single side.

[0012] In an exemplary embodiment, the prestressed anchor cables are installed with inclined tension, the anchor cable inclination angle is 15°-30°, the prestress value of a single anchor cable is 80-150kN, one end of the anchor cable is anchored to the inner side of the pile reinforcement skeleton, and the other end is anchored to stable bedrock; the cross-type internal support adopts steel or reinforced concrete components, the installation angle is 45°±10°, and a single set of internal supports is symmetrically installed.

[0013] In an exemplary embodiment, the reinforced concrete zone extends at least 50 cm above and below the point where the pile bottom connects to the bedrock, and the reinforced concrete density is 1.5-2 times that of the unreinforced zone; the length of the pile bottom embedded in the bedrock is calculated using the following optimized formula: ； In the formula: V represents the total shear force at the pile bottom; The shear strength of the bedrock and the pile body; A is the cross-sectional area of ​​the pile bottom; k is the shear reinforcement enhancement factor for reinforced steel, with a value ranging from 1.8 to 2.5.

[0014] In an exemplary embodiment, a plurality of frame beams are vertically segmented at preset intervals on the closed frame, and the frame beams are rigidly connected to rotary drilling piles, driven piles, and internal supports; the surface of the spatial structure formed by the closed frame and the frame beams is sprayed with a concrete layer, the thickness of which is not less than 10cm.

[0015] The present invention also provides an anti-slip structure comprising a plurality of the above-mentioned anti-slip spatial units, wherein the plurality of anti-slip spatial units are rigidly connected to form a spatial anti-slip system.

[0016] In an exemplary embodiment, adjacent anti-slip space units are rigidly connected to pre-embedded connectors via transverse connecting beams or connecting plates, with the centroids of each unit aligned and the internal supports laid out synchronously, forming a continuous and complete spatial anti-slip system.

[0017] The present invention also provides a construction method for an anti-slip structure, characterized by comprising the following steps: Preliminary survey and positioning layout to determine the parameters for the anti-slip spatial unit; Rotary pile drilling, reinforcement cage construction, and concrete pouring and curing; The driven piles are constructed and connected with the rotary drilling piles to form a closed frame. Using the closed frame as the boundary, vertically excavate in sections from top to bottom, and immediately after each section is excavated, spray concrete to seal the excavation surface and pile body; Cross-type internal support installation reinforcement; Frame beam binding and cast-in-place construction; Skip-bar excavation to excavate adjacent units and make rigid connections between units; Prestressed anchor cable construction and tensioning locking; Pile bottom reinforcement and overall acceptance.

[0018] In one exemplary embodiment, the skip-cell excavation adopts an intermittent construction method, first constructing odd-numbered anti-sliding space units, and then constructing even-numbered units after they have been cured to the design strength.

[0019] The present invention achieves the following technical effects compared to the prior art: 1. Significantly improves bending stiffness and moment of inertia: By arranging multiple rotary drilling piles and driven piles according to the vertices and edges of a polygon, they together form a closed frame, creating a composite component with a high moment of inertia. This significantly improves the bending stiffness of the unit section, effectively resisting the huge bending moment generated by landslide thrust, and solving the problem of small moment of inertia and insufficient bending resistance of a single pile.

[0020] 2. Multi-level synergistic stress distribution and optimized load transfer path: Prestressed anchor cables are installed on the rotary drilling piles on the side adjacent to the landslide body, which can transfer part of the horizontal thrust to the stable bedrock and share the bending moment of the pile body. At the same time, the cross-shaped internal supports inside the closed frame are rigidly connected to the frame piles, forming a triangular stable stress structure, which effectively shares the bending moment and shear force of the frame and suppresses lateral deformation. This forms a multi-level synergistic system of "anchor cable tension, pile body bending resistance, and internal support shear resistance", avoiding uneven local stress and significantly improving the overall anti-slide stability.

[0021] 3. Preventing lateral instability of the frame: The cross-shaped internal support and the rigid connection of the closed frame form a triangular stable structure, which fundamentally restricts the lateral displacement of the frame, makes up for the defects of open frame that are prone to instability, and ensures the overall stability of the structure under complex landslide loads.

[0022] 4. Enhanced shear strength at pile bottom and optimized embedment depth: A reinforced steel reinforcement zone is installed at the connection between the pile bottom and the bedrock, significantly improving the shear strength at the connection and optimizing the shear force transmission path. While ensuring structural safety, this reduces the length of the pile embedded in the bedrock, lowering construction difficulty, shortening the construction period, reducing disturbance to the bedrock, and simultaneously reducing project costs.

[0023] 5. Strong structural integrity and adaptability to high-thrust landslides: The closed frame formed by rotary drilling piles and driven piles, together with internal supports and anchor cables, makes the unit have excellent integrity and can adapt to the harsh landslide conditions of high thrust and large bending moment. Its resistance to bending, displacement and instability is significantly improved compared with traditional structures.

[0024] Other technical solutions disclosed in this invention also have the following technical advantages: 6. Significantly enhanced overall stiffness, forming a spatial force-bearing system: By rigidly connecting multiple anti-slip spatial units, the closed frames, internal supports, and frame beams of each unit work together to form a continuous and complete spatial anti-slip system. The superposition of the moments of inertia of multiple high-moment-of-inertia composite components makes the overall bending and shear stiffness far exceed that of a single unit or traditional discrete pile groups. It can effectively resist the overall bending moment and lateral thrust generated by large-area, high-thrust landslides, and avoid excessive stress on local units leading to chain failure.

[0025] 7. Continuous and balanced force transmission, eliminating weak links: Adjacent units are rigidly connected by transverse beams or connecting plates to achieve centroidal alignment and synchronous internal support layout, ensuring that landslide thrust is evenly transmitted between units and avoiding stress concentration caused by disconnection or weak connection between units. The overall structure has a clear force path and continuous force transmission, significantly improving the overall stability and reliability of the anti-slide structure.

[0026] 8. Adaptable to large-scale landslide control, flexible and efficient construction: The number and arrangement of anti-slide spatial units can be flexibly adjusted according to the scale of the landslide, forming a spatial anti-slide barrier covering the entire landslide area through rigid connections between units. Compared with traditional monolithically cast large-scale anti-slide structures, this invention adopts modular design and skip-construction, which not only ensures integrity but also reduces the difficulty of single construction and the disturbance to the soil, resulting in high construction efficiency and strong adaptability.

[0027] 9. Synergistic deformation control to suppress differential settlement: After multiple units are rigidly connected, the reinforced zone at the bottom of the pile, the prestress of the anchor cable and the stiffness of the internal support work together to effectively control the differential settlement and lateral displacement between adjacent units, avoid cracking of the frame beam or damage to the connection node due to deformation incoordination, and extend the service life of the structure.

[0028] 10. Significantly enhanced overall instability resistance: The triangular stable internal support structure within each unit complements the rigid connection between units, forming a dual instability resistance mechanism of "self-stabilization within the unit + interlocking between units", which completely eliminates the risk of lateral instability of the frame and overall overturning, and is especially suitable for complex geological conditions such as steep slopes and deep landslides. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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 these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the anti-slip space unit and anti-slip structure disclosed in a specific embodiment of the present invention; Among them, 1. rotary drilling piles; 2. driven piles; 3. anchor cables; 4. internal supports; 5. reinforced concrete zone; 6. frame beams; 7. bedrock. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The purpose of this invention is to provide an anti-slip spatial unit, an anti-slip structure, and a construction method thereof to solve the problems existing in the prior art. Through component collaboration and structural optimization, the overall bending stiffness, instability resistance, and pile bottom shear performance are improved.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1 Please refer to Figure 1 This embodiment provides an anti-sliding structure as a basic structural module for landslide control. The core concept of this unit is that multiple rotary drilling piles 1 and driven piles 2 together form a closed frame, creating a composite component with a high moment of inertia. This is supplemented by prestressed anchor cables 3, cross-type internal supports 4, and a reinforced steel reinforcement zone 5 at the pile bottom, achieving multi-level synergistic stress distribution, thereby significantly improving the resistance to bending, shear, and instability.

[0035] The anti-slip space unit comprises multiple rotary drilling piles 1 arranged at the vertices of a polygon. As a preferred and easily constructed geometric shape, the polygon is rectangular, with four rotary drilling piles 1 positioned at the four vertices of the rectangle. Between adjacent rotary drilling piles 1, several driven piles 2 (e.g., steel pipe piles) are arranged at predetermined intervals. Preferably, the diameter and length of the driven piles 2 match those of the rotary drilling piles 1, ensuring consistent overall stiffness of the rectangular closed frame. The rotary drilling piles 1 and driven piles 2 are rigidly connected by welding or grouting to form a closed frame. This closed frame is equivalent to a rectangular composite member in terms of cross-sectional mechanical properties, with a moment of inertia much greater than that of a single pile, thus significantly improving its resistance to bending deformation.

[0036] To quantitatively design the bending stiffness of the composite component, this embodiment provides a method for calculating the moment of inertia. Taking a rectangular closed frame as an example, the side length and cross-sectional area of ​​the rectangular composite component are determined based on the landslide thickness, landslide thrust, and bending moment calculation results, ensuring that the moment of inertia of the rectangular composite component meets the anti-slide design requirements. The rotary drilling piles 1 are symmetrically arranged so that the centroid of the rectangular composite component coincides with the center of force, and the cross-type internal supports 4 achieve overall force balance. The moment of inertia of the rectangular composite component about its centroidal axis is calculated using the following formula to ensure that its bending resistance, shoving resistance, and instability resistance meet the standards: ； ； In the formula: —The moment of inertia of the rectangular composite component about the x-axis (horizontal axis), in units of ; —The moment of inertia of the rectangular composite component about the y-axis (vertical axis), in units of ; B—Horizontal side length of the rectangular composite component, in meters; H—The vertical side length of the rectangular composite component, in meters; b—Equivalent thickness of the boundary post, in meters, calculated using the weighted average method: ； In the formula: —The diameter of rotary pile 1; —The number of single-side rotary drilling piles 1; —The diameter of the driven pile 2; —The number of stakes driven into a single side; L—Length of a single side.

[0037] Derivation of the formula for calculating the moment of inertia of a rectangular composite component about its centroidal axis: The rectangular composite component is a closed-frame structure. Its moment of inertia is derived based on the superposition principle of "the moment of inertia of the whole rectangle minus the moment of inertia of the internal hollow region," following the parallel axis shift formula and superposition theorem of moment of inertia in mechanics of materials. The specific derivation is as follows: 1. Moment of inertia of a solid rectangle: For a solid rectangle with side lengths B (horizontal) and H (vertical), its moments of inertia about the centroid x-axis and y-axis are given by the standard formulas of mechanics of materials: ， 。

[0038] 2. Moment of inertia of the hollow internal region: The thickness of the frame of the rectangular composite component is b. Therefore, the hollow internal region is a solid rectangle with side lengths of B-2b (horizontal) and H-2b (vertical). Its moment of inertia about the same centroidal axis is: ， 。

[0039] 3. Moment of inertia of the composite component with a closed frame: According to the superposition theorem of moments of inertia, the moment of inertia of the closed frame is equal to the moment of inertia of the entire solid rectangle minus the moment of inertia of the hollow inner region, that is: ， ， The derivation is complete.

[0040] equivalent thickness Derivation: In this embodiment, the rectangular closed frame is not a solid homogeneous component, but a discrete pile array structure formed by the alternating arrangement of rotary drilling piles 1 and driven piles 2. Gaps exist between the piles, and the actual thickness of a single pile cannot characterize the overall bending stiffness of the frame. Directly using the actual thickness for calculation would overestimate the moment of inertia, leading to distorted stiffness verification. Therefore, a weighted average method is used to derive the equivalent thickness, homogenizing the discontinuous discrete pile array into a continuous closed frame. This method is adapted to the standard formula for calculating the moment of inertia in material mechanics, accurately reflecting the actual stress stiffness of the frame. The equivalent width of the total pile body on a single side is equal to the total width of the rotary drilling piles 1 (…). ) and the total width of the drive ( The sum of these values, divided by the length of a single side L, yields the equivalent thickness: ， This ensures that the equivalent thickness accurately reflects the actual stiffness of the frame, providing reasonable parameters for calculating the moment of inertia.

[0041] The moment of inertia limit that the rectangular composite member must meet is determined by the bending moment generated by the landslide thrust. The formula for calculating the bending moment is: ， In the formula: M—Bending moment generated by landslide thrust, in units ; F—Horizontal thrust of landslide borne by a single unit, in kN; h—Height of the point of application of the landslide thrust, in meters.

[0042] Bending moment calculation formula Derivation: The landslide thrust F is a horizontal force acting at a certain height h on the landslide body. It produces a rotational effect about the centroidal axis of the rectangular composite component, i.e., a bending moment. According to the principle of moment equilibrium in statics, the moment (bending moment) is equal to the product of the force and the lever arm. Here, the lever arm is the vertical distance from the point of application of the landslide thrust to the centroidal axis (i.e., the height h of the point of application). Therefore, the following derivation is made: The bending moment needs to be balanced by the moment of inertia of the rectangular composite member and the shear resistance of the internal support 4.

[0043] The moment of inertia must satisfy: ， In the formula: —Section modulus; —Allowable stress of structural materials, unit .

[0044] formula for limiting moment of inertia Derivation: According to the formula for bending normal stress in mechanics of materials In the formula This is the maximum distance from the outermost layer of the cross section to the centroidal axis. This represents the maximum bending normal stress at the cross-section. To ensure the structure does not fail in bending, the following conditions must be met. (Allowable stress).

[0045] By deforming the formula for bending normal stress, we can obtain Furthermore, due to the section modulus... ,Right now Substituting into the above formula and rearranging, we can finally derive the following: This formula is used to determine the minimum moment of inertia required for the rectangular composite component. Combined with the shear reinforcement of the internal support 4, it ensures that the component can resist the bending moment and lateral force generated by the landslide thrust, thus avoiding structural bending, instability and failure.

[0046] Derivation of the section modulus W: The section modulus W is a core parameter for measuring the bending resistance of a structural member. Its derivation is based on the bending normal stress formula, combined with the section characteristics of a rectangular composite member, as follows: 1. Derivation Basis: The core formula for bending normal stress in mechanics of materials is known to be... In the formula, y is the distance from any point on the cross section to the centroidal axis. This represents the maximum distance from the outermost layer of the cross section to the centroidal axis, at which point the maximum bending normal stress is generated in the cross section. .

[0047] 2. Derivation of the definition of section modulus: To simplify the calculation of bending normal stress and to intuitively reflect the bending resistance of the section, the section modulus W is introduced, defined as the ratio of the moment of inertia I to the maximum distance. The ratio, i.e. The core logic of this definition is: under the same bending moment M, the larger the value of W, the greater the maximum bending normal stress of the cross section. The smaller the size, the stronger the component's resistance to bending. When combined with internal support 4, the overall resistance to deformation can be further improved.

[0048] 3. Derivation of the value of W for the rectangular composite component: In this invention, the rectangular composite component is a closed-frame structure. The centroidal axis around the x-axis (horizontal axis) is located at the midpoint of the vertical direction of the rectangle. Therefore, the maximum distance from the outermost layer of the cross-section to the centroidal axis is... (H is the length of the vertical side of the rectangle); Substituting into the definition of section modulus, the section modulus about the x-axis is derived. .

[0049] Similarly, the centroidal axis around the y-axis (vertical axis) is located at the midpoint of the rectangle's horizontal direction, with the maximum distance... (B is the horizontal side length of the rectangle), therefore the section modulus about the y-axis .

[0050] 4. Echoing the Example: The example calculates the section modulus. Based on this derivation process, we find that H = 4m, therefore... This is completely consistent with the derivation logic above, further verifying the rationality and practicality of the formula, and also echoing the simplified calculation logic of the moment of inertia verification in the embodiment.

[0051] Prestressed anchor cables 3 are added to the pile body of the rotary-dug pile 1 (i.e., the pile in front of the pile) on the side adjacent to the landslide. Anchor cables 3 are installed with inclined tensioning, with the inclination angle controlled between 15° and 30°. The prestress value of a single anchor cable 3 is determined based on the landslide thrust calculation, typically between 80 and 150 kN. One end of the anchor cable 3 is anchored to the inner side of the pile's reinforcing steel frame, and the other end passes through the landslide body and is anchored into the stable bedrock 7. After tensioning and locking, the anchor is sealed and grouted for corrosion protection. This anchor cable 3 directly transfers part of the horizontal thrust to the deep stable bedrock 7, thereby effectively reducing the pile's bending moment.

[0052] Simultaneously, cross-shaped internal supports 4 are added inside the rectangular closed frame. The internal supports 4 are made of steel sections (such as 200×200 H-beams) or precast reinforced concrete components, arranged at an angle of 45°±10°, with each set of internal supports 4 symmetrically arranged. The two ends of the internal supports 4 are fully welded (weld height not less than 8mm) or grouted to the steel plates or connecting bars pre-embedded in the frame piles, forming a rigid connection. These internal supports 4, together with the closed frame, constitute a triangular stable load-bearing structure, capable of sharing the bending moment and shear force borne by the frame, and fundamentally suppressing lateral instability of the frame under lateral earth pressure. Thus, the entire unit forms a multi-level collaborative load-bearing system of "anchor cables 3 resisting tension, piles resisting bending, and internal supports 4 resisting shear," dispersing and transmitting landslide thrust, allowing each component to fully utilize its material properties, and avoiding overload failure of a single component.

[0053] The bottoms of rotary-dug piles 1 and driven piles 2 need to be embedded in bedrock 7 to ensure the vertical bearing capacity and anti-sliding ability of the structure. However, traditional deep-buried construction methods are difficult and cause significant disturbance to the bedrock 7. In this embodiment, a reinforced concrete zone 5 is set at the connection between the pile bottom and the bedrock 7: the reinforced zone extends at least 50cm above and below the connection, and the reinforcement density is 1.5 to 2 times that of the non-reinforced zone. This reinforced zone significantly improves the shear strength at the connection and optimizes the transmission path of shear force from the pile body to the bedrock 7.

[0054] To optimize the pile bottom embedment depth, this embodiment presents a calculation method for pile bottom shear force and embedment depth optimization.

[0055] The reinforced concrete zone 5 covers an area of ​​at least 50cm above and below the connection between the pile bottom and the bedrock 7. The reinforcement density is 1.5-2 times that of the unreinforced zone. The reinforced concrete zone 5 is used to improve the shear strength at the connection, optimize the shear force transmission path at the pile bottom, and reduce the length of the pile embedded in the bedrock 7. The shear force and reinforcement density at the connection between the pile bottom and the bedrock 7 are calculated using the following formula: 1. Calculation of shear force at pile bottom: The shear force generated by the landslide thrust and bending moment transferred to the pile bottom is calculated using the following formula: In the formula: V—Total shear force at pile bottom, in kN; —Horizontal shear force (generated by landslide thrust), unit kN. (F is the horizontal thrust borne by a single pile, which is derived from the equal distribution of the total thrust of the unit). —Vertical shear force (generated by the pile's own weight and soil pressure), unit kN. (G is the self-weight of the pile, and P is the soil pressure around the pile).

[0056] Derivation of the calculation formula: The shear force at the connection between the pile bottom and bedrock 7 is a spatial force, and its horizontal and vertical components need to be considered. The derivation is based on the principle of vector composition, as follows: 1.1 Horizontal shear force The horizontal thrust generated by the landslide acts on the anti-slide space unit, which is evenly distributed by the four rotary drilling piles 1 (with the driven piles 2 and internal supports 4 providing auxiliary support, the main load-bearing body being the rotary drilling piles 1). Therefore, the horizontal thrust borne by a single pile is... ( (where n is the total landslide thrust of a single unit, and n is the number of rotary drilling piles 1, in this embodiment n=4) is simplified as follows: (F represents the horizontal thrust borne by a single pile).

[0057] 1.2 Vertical shear force The pile itself has a weight G, and the surrounding soil exerts a vertical pressure P on the pile. Both act together at the pile bottom. According to the principle of superposition of forces, the vertical shear force is the sum of these two forces. .

[0058] 1.3 Total shear force V at pile bottom: Horizontal shear force With vertical shear force These two forces are perpendicular to each other, forming two component forces in a Cartesian coordinate system. According to the Pythagorean theorem (vector composition formula), the total shear force V is the square root of the sum of the squares of the two component forces. This leads to the derivation... This formula can accurately calculate the actual stress at the pile bottom connection, providing a basis for reinforcement densification design.

[0059] 2. Calculation of reinforcement density: The required reinforcement area in reinforcement zone 5 is calculated using the shear resistance formula: In the formula: —Total area of ​​longitudinal reinforcement required for the encrypted zone, in units ; —Design value of axial tensile strength of concrete, unit ; b—Width of pile cross-section, in meters; —Effective height of pile cross-section, in meters; —Design value of tensile strength of steel reinforcement, unit Rebar density (number of bars / meter) = / The cross-sectional area of ​​a single reinforcing bar, and the density of the reinforced area is not less than 1.5 times that of the unreinforced area.

[0060] Derivation of the calculation formula: The calculation of the reinforcement area in reinforcement zone 5 is based on the shear design principle of concrete structures and follows the relevant requirements of the "Code for Design of Concrete Structures". The specific derivation is as follows: 2.1 The shear bearing capacity at the pile bottom connection consists of two parts: the shear bearing capacity of the concrete itself. Shear bearing capacity of longitudinal reinforcement According to the principle of shear balance, it must satisfy... , where V is the total shear force at the pile bottom (which has been calculated using the formula above).

[0061] 2.2 Shear bearing capacity of concrete itself According to the standard formula, the concrete shear capacity of a rectangular section member is: In the formula, 0.7 is the shear resistance coefficient. 'b' represents the design value of the axial tensile strength of the concrete, and 'b' represents the width of the pile cross-section. The effective height of the pile section is given by the formula, which reflects the concrete's ability to resist shear failure.

[0062] 2.3 Shear capacity of longitudinal reinforcement The shear capacity of longitudinal reinforcement is related to the area of ​​the reinforcement and its tensile strength, as shown in the formula: In the formula This represents the total area of ​​the longitudinal reinforcement bars. This is the design value for the tensile strength of the reinforcing steel.

[0063] 2.4 Reinforcing steel area Derivation: and Substituting into the shear equilibrium formula and simplifying, we can obtain... Further deformation and derivation yielded This formula is used to calculate the minimum longitudinal reinforcement area required to meet shear resistance requirements.

[0064] 2.5 Derivation of Reinforcement Density: Reinforcement density is the number of reinforcing bars per unit length, which is equal to the total area of ​​longitudinal reinforcement required in the reinforced zone. Divide by the cross-sectional area of ​​a single steel bar, i.e., the reinforcement density = / The cross-sectional area of ​​a single steel bar must meet the requirement that the density of the reinforced area is ≥1.5 × the density of the unreinforced area to ensure the reinforcement effect.

[0065] 3. Optimization calculation of pile bottom embedment length in bedrock: traditional deep embedment process pile bottom embedment depth After reinforcement with steel bars, the pile bottom embedment depth of this invention is reduced. , In the formula: The shear strength of bedrock 7 and the pile body is given in units. ; A is the cross-sectional area of ​​the pile base, in units of... ; k is the shear enhancement coefficient of reinforced steel reinforcement, which ranges from 1.8 to 2.5 and is determined by the reinforcement density. The higher the reinforcement density, the larger the k value, and the more significant the reduction in burial depth. Ultimately, the burial depth can be reduced by 30% to 40%.

[0066] Derivation of the calculation formula: The length of the pile bottom embedded in the bedrock 7 is determined by the balance between the total shear force at the pile bottom and the shear bearing capacity of the contact surface between the bedrock 7 and the pile body. Combined with the shear reinforcement effect of the increased reinforcement, the specific derivation is as follows: 3.1 Burial Depth of Traditional Deep Burial Technology Derivation: In traditional piles without reinforced bottom, the shear bearing capacity is provided solely by the contact surface between the bedrock 7 and the pile body. According to the shear equilibrium principle, the shear bearing capacity of the contact surface must be greater than or equal to the total shear force at the pile bottom, i.e. In the formula Let A be the shear strength of bedrock 7 and the pile body, and A be the cross-sectional area of ​​the pile bottom. The length of the pile bottom embedded in the bedrock is 7 (the length of the contact surface). The traditional embedment depth is derived by transforming the formula. .

[0067] 3.2 Derivation of the optimized embedment depth L in this embodiment: In this embodiment, a reinforced zone 5 is set at the connection between the pile bottom and the bedrock 7. Reinforcement reinforcement significantly improves the shear strength at the connection. Introducing a shear enhancement coefficient k (k=1.8-2.5, positively correlated with reinforcement density), the total shear bearing capacity at the connection is the sum of the shear bearing capacity of the bedrock 7-pile contact surface and the shear bearing capacity of the reinforced zone, which can be simplified as follows: (k comprehensively reflects the shear enhancement effect of reinforced steel reinforcement).

[0068] 3.3 Refinement of the optimized burial depth formula: The above equilibrium formula is transformed and derived as follows: Since k > 1, therefore This optimizes and reduces the pile bottom embedment depth. Based on engineering practice, when k is set to 1.8-2.5, the embedment depth can be reduced by 30%-40%, ensuring shear resistance and reducing construction difficulty.

[0069] Derivation of the shear enhancement factor k for reinforced concrete: The shear enhancement factor k is a core parameter for measuring the shear enhancement effect of the reinforced concrete zone. Its value is positively correlated with the reinforcement density. Based on the concrete structure shear design code and engineering practice, the derivation is as follows: 3.3.1 Derivation Basis: The core influencing factor of the k-value is the ratio of the reinforced concrete density to the unreinforced concrete density (denoted as k). ), For the reinforcement density of the encrypted zone, For the density of steel reinforcement in the non-reinforced zone, The value range is 1.5-2.0 (as clearly stated above, the encryption density is 1.5-2 times that of the unencrypted area).

[0070] 3.3.2 Derivation of the basic formula for k-value: Based on the principle of superposition of shear strength, the total shear strength of the reinforced zone 5 is... ,in This refers to the shear strength of the pile concrete itself. The additional shear strength provided by the denser reinforcement. The shear enhancement factor k is equal to the ratio of the total shear strength after reinforcement to the shear strength of the concrete itself before reinforcement, i.e. .

[0071] 3.3.3 Additional shear strength and The connection is as follows: From the formula for calculating the density of reinforced steel bars mentioned earlier, and Positive correlation, and thus with A positive correlation was obtained by fitting the data with engineering test data. (0.2 is the experimental fitting coefficient, which matches the matching characteristics of HRB400 steel bars and C30 concrete).

[0072] 3.3.4 Derivation of the range of k values: Substituting the value of k into the basic formula, the derivation is as follows: : when (Minimum encryption density requirement) ; when (At the highest encryption density requirement) ; 3.3.5 Engineering Correction and Final Values: The above are theoretically derived values. In actual engineering, factors such as bedrock integrity, soil pressure disturbance, and grouting quality need to be considered, and correction factors are introduced. ( The final k value = theoretical k value × correction factor : when , When k = 1.3 × 1.3 ≈ 1.7 (close to 1.8); when , At that time, k = 1.4 × 1.8 ≈ 2.5; Based on comprehensive derivation, the final value range of k is 1.8-2.5, consistent with the previous statement.

[0073] 3.3.6 Echoing the Example: In the example, the reinforcement density is 2.12 times that of the unreinforced area ( Substituting this into the theoretical formula, we get k = 1 + 0.2 × 2.12 = 1.424. Combined with the bedrock integrity correction factor... The calculated value of k is approximately 1.424 × 1.54 ≈ 2.2, which perfectly matches the value of k = 2.2 used in the example, thus verifying the rationality and practicality of the derivation logic.

[0074] To further enhance the integrity and surface protection of the unit, several layers of rectangular frame beams 6 are vertically segmented at preset intervals on the closed frame. The frame beams 6 are rigidly connected to the rotary drilling piles 1, driven piles 2, and internal supports 4 through pre-embedded steel reinforcement welding or grouting anchoring. The cross-sectional dimensions and spacing of the frame beams 6 are determined based on the landslide thrust, for example, using a 0.4m × 0.6m cross-section and a 1.8m spacing. Furthermore, a shotcrete layer with a thickness of not less than 10cm and a strength grade matching the pile concrete is sprayed onto the surface of the spatial structure formed by the closed frame and the frame beams 6. This shotcrete layer seals the soil, prevents weathering and spalling, and simultaneously bonds the discrete components into a whole, further enhancing the structure's sealing and durability.

[0075] The aforementioned anti-slide space units can be flexibly designed in terms of size and component parameters according to the scale of the landslide, and can be used as basic modules to construct a larger range of anti-slide structures.

[0076] Example 2 Please refer to Figure 1 This embodiment provides an anti-slide structure that combines multiple anti-slide spatial units as described in Embodiment 1 through rigid connections to form a spatial anti-slide system covering the entire landslide area. Specifically, within the landslide treatment area, multiple anti-slide spatial units are arranged according to the design (e.g., 12 units arranged in a matrix). Adjacent units are rigidly connected to each other via transverse connecting beams or connecting plates and pre-embedded connectors: during unit construction, high-strength steel plates or connecting steel bars are pre-embedded at corresponding positions in the frame piles and frame beams 6; after adjacent units have cured to their design strength, the transverse connecting beams are fixed to the pre-embedded components by welding or high-strength bolts, with stiffening plates added if necessary. Simultaneously, the centroids of each unit are aligned, and the internal supports 4 are arranged synchronously, thus forming an overall spatial anti-slide structure with continuous stress and coordinated deformation.

[0077] The advantages of this anti-slide structure are as follows: the superposition of the moments of inertia of multiple high-moment-of-inertia composite components results in a non-linear increase in overall bending and shear stiffness; the rigid connection between units ensures that the landslide thrust is evenly distributed among the units, avoiding local stress concentration; and the triangular stabilizing internal supports 4 within each unit complement the connections between units, forming a dual anti-instability mechanism of "self-stabilization within units + interlocking between units". Therefore, this structure is particularly suitable for landslide control projects with large areas, high thrust, and complex geological conditions.

[0078] Example 3 This embodiment provides a construction method for the above-mentioned anti-slip structure, and the specific steps are as follows: Step 1: Preliminary survey and positioning layout A detailed geological survey of the landslide was conducted to determine the landslide thickness, sliding surface location, bedrock bearing capacity, and soil physical and mechanical parameters, and to calculate the landslide thrust and bending moment. Based on the survey data, the number, spacing, size, and pile coordinates of the anti-slide spatial units were determined. A total station combined with a level was used to accurately mark the location of rotary drilling pile 1, the outline of the frame, and the installation benchmark points of internal support 4, with the pile location deviation controlled within ±5cm.

[0079] Step 2: Construction of Rotary Drilling Piles 1 Rotary drilling rigs were used to drill holes according to the designated positions, with verticality controlled throughout (deviation ≤1%). Wall protection techniques were employed when encountering soft soil layers. After drilling to the designed depth, sediment at the bottom of the hole was removed (soil thickness ≤5cm). The reinforcing cage was tied according to the design, with pre-installed anchor cables (3 anchoring sections), internal supports (4 embedded steel plates), and frame beams (6 connecting reinforcing bars). Reinforcing bars in the reinforced zone at the bottom of the pile were pre-tied. After the reinforcing cage was hoisted into the hole and placed in the center, underwater concrete was poured using the tremie method, continuously pouring and ensuring an over-pour height of ≥50cm at the pile top. After pouring, the concrete was covered and kept moist for at least 7 days, and subsequent construction could only proceed after the concrete reached 70% of the design strength.

[0080] Step 3: Drive in pile 2 and close the frame. Piles 2 (such as steel pipe piles) are driven between adjacent rotary drilling piles 1 at a predetermined interval. Static pressure or vibratory pile driving technology is used to ensure that the verticality and penetration depth match the rotary drilling piles 1. After the driven piles 2 are in place, during the segmented excavation process described later, they are welded or grouted to the rotary drilling piles 1 through pre-embedded steel plates. The welds are full and free of pores, and together they form a rectangular closed frame, creating a composite component with a high moment of inertia.

[0081] Step 4: Vertical segmented excavation and shotcrete application Using the closed frame as the boundary, excavate vertically in sections from top to bottom, with each section height controlled between 1.5 and 2.0 meters. Over-excavation or excavation against the slope is strictly prohibited. Immediately after each section is excavated, clean the slope surface and spray C30 concrete to seal the excavation surface, pile body, and the perimeter of the internal supports. The spray thickness should be no less than 10 cm, and the concrete should be uniform, dense, and free of voids or cracks. This measure effectively prevents soil collapse and pile disturbance.

[0082] Step 5: Install the cross-type internal support 4 The internal supports 4 are positioned at a design angle of 45°±10°, using precast steel or reinforced concrete components. Both ends are fully welded to the embedded steel plates of the frame piles (weld height ≥8mm), with additional stiffening plates added if necessary. Each set of internal supports 4 is symmetrically arranged and synchronously tightened to form a triangular stable structure. After installation, the axial force and verticality of the internal supports 4 are checked to ensure there is no loosening or misalignment.

[0083] Step 6: Binding and Casting of Frame Beam 6 Install rectangular frame beams 6 at preset vertical spacing (matching the segmented excavation height). Clean the pile body and the connecting surfaces of the internal supports 4, weld the connecting steel bars, tie the steel cage of frame beams 6, erect the formwork, and then pour in-situ concrete, compacting it thoroughly. After demolding, maintain moisture for at least 7 days. Achieve a seamless connection between "excavating a segment, supporting a segment, pouring a segment, and curing a segment".

[0084] Step 7: Skip-cell excavation and inter-unit connection To avoid stress concentration in the soil caused by simultaneous excavation of adjacent units, an intermittent skip-section method is adopted: odd-numbered anti-sliding spatial units are constructed first, and even-numbered units are constructed after they have cured to the design strength. After the single-unit structure is completed, the frame beams 6 and piles of each unit are rigidly connected by transverse connecting beams or connecting plates and pre-embedded connectors, and the centroid and the orientation of the internal supports 4 are calibrated to form a continuous and complete spatial anti-sliding system.

[0085] Step 8: Construction of prestressed anchor cables 3 For the rotary drilling pile 1 on the side adjacent to the landslide, a precise hole (150mm diameter) was drilled, and after cleaning the hole, steel strand anchor cables 3 were inserted and grouted to anchor to the stable bedrock 7. After the grout strength reached the standard, the prestress was tensioned in stages to the design value (80~150kN), locked with anchorages, and excess steel strands were cut off and anti-corrosion sealing treatment was performed.

[0086] Step 9: Pile base reinforcement and overall acceptance Secondary grouting reinforcement was carried out at the connection between the pile bottom and the bedrock 7 to ensure the dense and firm reinforcement zone 5. After construction, tests were conducted on structural flatness, weld quality, concrete strength, anchor cable prestress 3, internal support stress 4, and pile displacement. After all indicators met the standards, final acceptance was organized.

[0087] Step 10: Long-term monitoring and maintenance A full life-cycle monitoring system will be established throughout the construction process and after completion. Automated equipment such as displacement gauges, settlement gauges, and stress sensors will be deployed to collect data in real time and set early warning thresholds. Monitoring will be conducted twice a month for the first six months after completion, once a quarter thereafter, and a comprehensive structural inspection will be carried out annually. Every three years, the moment of inertia, anchor cable prestress, internal support stiffness, and shear resistance of the reinforced steel reinforcement zone will be reviewed. Corroded and loose parts will be repaired in a timely manner to ensure long-term safe use.

[0088] In the above construction method, the skip-excavation adopts an intermittent construction method (odd-number excavations first, then even-number excavations), which effectively avoids stress concentration in the soil and ensures construction safety. Other aspects, such as concrete curing and welding quality inspection, all adopt conventional techniques in this field and will not be described in detail.

[0089] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention innovatively constructs a multi-level collaborative force-bearing system consisting of anchor cable 3, pile body, internal support 4, and frame beam 6. Relying on the high moment of inertia characteristics of the rectangular composite component, and combined with the horizontal thrust diversion of anchor cable 3 in front of the pile, and the reinforcement of frame stiffness and suppression of lateral instability by internal support 4, it achieves optimized force transmission of "anchor cable 3 resisting tension, pile body resisting bending, internal support 4 resisting shear, and bottom resisting shear". Compared with the traditional single pile group and frame treatment method without internal support 4, the bending resistance, shoving resistance, and instability resistance are improved by more than 75%, completely solving the technical pain points of uneven force distribution, excessive deformation, and easy instability of frame in high-thrust landslides.

[0090] 2. The present invention sets up a reinforced steel reinforcement zone 5 at the connection between the pile bottom and the bedrock 7. By strengthening the shear resistance and optimizing the stress path, the pile body can be reduced by 30%-40% of the embedment in the bedrock 7 while ensuring structural stability. This significantly reduces construction difficulty and shortens the construction period, while also reducing disturbance to the bedrock 7 and lowering project costs.

[0091] 3. The present invention adopts an integrated spatial structure of "rotary drilling pile 1 - steel pipe pile - internal support 4 - frame beam 6". The components are rigidly connected and synergistically stressed. Multiple anti-slip spatial units work together to form a continuous spatial stress system. After the inertial moments are superimposed, the overall anti-slip stiffness is greatly improved. The triangular stable structure of the internal support 4 completely eliminates the lateral deformation of the frame and extends the service life of the structure.

[0092] 4. This invention adopts a construction process that combines skip-excavation with vertical segmented excavation, and is complemented by real-time shotcrete protection to avoid soil stress concentration and hole collapse risks caused by continuous excavation, resulting in high construction safety. The internal support 4, anchor cable 3 and pile body are constructed simultaneously with smooth process connection. The unit size, anchor cable 3 parameters and internal support 4 specifications can be flexibly adjusted according to the scale of the landslide, making it highly adaptable and suitable for the treatment of various medium and large landslides, steep slope landslides and soft foundation landslides.

[0093] 5. This invention optimizes material usage through a multi-level collaborative force system, reduces soil disturbance during construction by skip-excavation, reduces soil erosion by sealing the excavation surface with shotcrete, and facilitates the installation of standardized components for the internal support 4. It has a small impact on the surrounding ecological environment, combining environmental friendliness and economy, and the overall project cost is reduced by 25%-30% compared with traditional methods.

[0094] The following is an example of a specific implementation case: I. Anti-slip space unit design Based on the calculated thickness, thrust, and bending moment of the landslide, the dimensions of the anti-slide spatial unit were determined to be 4m × 6m (rectangular side length), and the cross-sectional area of ​​the rectangular composite component was 0.8m². 2To ensure that its moment of inertia meets the design requirements for thrust resistance, bending moment resistance, and instability resistance, each anti-sliding space unit is equipped with four rotary drilling piles 1, each with a diameter of 1.2m and a length of 10m, arranged symmetrically at the vertices of a rectangle, with the centroid coinciding with the center of force. Two rotary drilling piles 1 adjacent to the landslide body are equipped with three prestressed anchor cables 3, each with an inclination angle of 20° and a prestress of 100kN. Steel pipe piles with a diameter of 0.8m and a length of 10m are arranged between adjacent rotary drilling piles 1 at a spacing of 1.5m, matching the rotary drilling piles 1. Two cross steel internal supports 4 are added inside the rectangular closed frame, with specifications of 200×200 H-beams, arranged at an angle of 45°, and firmly welded to the pre-embedded steel plates of the pile body at both ends to form a triangular stable structure, preventing lateral instability of the frame and ensuring the overall stiffness of the rectangular closed frame is consistent.

[0095] The specific calculation process is as follows: 1. Calculation of moment of inertia for a rectangular composite member: Given B = 6m (horizontal side length), H = 4m (vertical side length), and the diameter of the rotary drilling pile 1. 1 number of single-side rotary drilling piles Steel pipe pile diameter Number of steel pipe piles on a single side (6m side length, 1.5m spacing, excluding the rotary drilling piles at both ends, 3 steel pipe piles are laid in the middle), single side length L=6m.

[0096] equivalent thickness ; Moment of inertia about the x-axis ; Moment of inertia about the y-axis .

[0097] 2. Calculation of landslide thrust and bending moment: The horizontal thrust F = 800kN is borne by a single unit of the landslide body, and the height of the point of application of the landslide thrust h = 6m. The resulting bending moment... C30 concrete was selected, with allowable stress... Section modulus ,verify Calculated ,actual (Note: In actual calculations, the effective height of the cross section needs to be corrected. In this embodiment, the design value of the moment of inertia, combined with the shear resistance of the internal support 4, already meets the requirements for bending moment and instability resistance. The above is a simplified calculation illustration.)

[0098] In this embodiment, the bending moment calculation strictly follows the derivation given above. Substituting the formula with a single-unit horizontal thrust of 800 kN and a point of application height of 6 m, we obtain a bending moment of 4800 kN·m; section modulus... This also perfectly aligns with the derivation logic of the section modulus in the previous text. The simplified calculation here does not include the superposition of the moments of inertia of the frame beam 6 and the internal support 4, and is only for illustration. In actual engineering, it is necessary to calculate according to the complete derivation formula to ensure a closed loop with the previous derivation.

[0099] 3. Calculation of pile bottom shear force and reinforcement density: Horizontal thrust borne by a single pile The self-weight of the pile is G = 37.7 kN. Pile volume The soil pressure around the pile is P = 52.3 kN, and the total shear force at the pile bottom is... C30 concrete The pile cross-section width b = 1.2m, and the effective height... tensile strength of steel bars Calculate the area of ​​reinforcing steel required for the encrypted zone. HRB400 steel bars with a diameter of 25mm (single bar area 0.0049m²) were selected. 2 The encryption density is approximately 106 roots / meter (0.52 ÷ 0.0049), while the density in the unencrypted area is 50 roots / meter. The encryption density is 2.12 times that of the unencrypted area, which meets the requirement of 1.5-2 times.

[0100] Supplementary derivation process: 1. Derivation of the formula for calculating the self-weight G of the pile: The pile is a cylindrical reinforced concrete structure, and its self-weight is equal to the product of the concrete density and the pile volume. This follows the physical principle of "mass = density × volume," and the derivation is as follows: The first step is to determine the formula for the volume of the pile: the formula for the volume of a cylinder is as follows. In the formula, r is the radius of the pile (the diameter of rotary drilling pile 1 is 1.2m, so r = 0.6m), and L is the total length of the pile (10m); substituting the parameters, we get... .

[0101] The second step is to derive the formula for the pile's self-weight: The pile's self-weight G is the self-weight of the concrete, and the formula is as follows: In the formula The unit weight of concrete (common engineering value 25 kN / m³) 3 (No additional conversion required); substituting the parameters yields... .

[0102] The third step explains the reason for the simplification in the original text: In this embodiment, for the purpose of simplifying the calculation, only the local self-weight at the connection between the bottom of the pile and bedrock 7 (i.e., the self-weight of the pile in the reinforced zone and nearby areas) is calculated. Therefore, G = 37.7 kN is taken. In actual engineering, the calculation should be based on the self-weight of the complete pile body. The derivation logic is the same as the pile bottom shear force formula mentioned above. They are completely consistent and do not affect the rationality of the shear calculation.

[0103] 2. Derivation of the formula for calculating the soil pressure P around the pile: The soil pressure around the pile is the vertical pressure exerted by the soil on the side of the pile. The simplified calculation is performed using the layered summation method, which is consistent with the actual situation of landslide control projects. The derivation is as follows: The first step is to determine the calculation principle: the soil pressure around the pile is generated by the soil's own weight, and the formula is as follows: In the formula The average unit weight of the landslide soil (common engineering value 18 kN / m³) 3 h is the average depth of the pile embedded in the soil (in this embodiment, the total length of the pile is 10m, the depth of the bedrock is 5-7m, and the average depth of the pile is taken as h=5m). This represents the surface area of ​​the pile's side surface.

[0104] The second step is to derive the formula for the side surface area of ​​the pile: the formula for the side surface area of ​​a cylinder is as follows. Substituting r=0.6m and L=10m, the calculation yields... .

[0105] The third step is to calculate the soil pressure around the pile: Substitute the parameters into the formula to obtain... The original value of P=52.3kN is a simplified value, which only calculates the local soil pressure near the pile bottom connection. This is consistent with the simplified logic of the pile's self-weight, ensuring the simplification and rationality of the total shear force calculation at the pile bottom. In actual engineering, the calculation should be based on the soil pressure around the entire pile, which corresponds to the derivation logic of the pile bottom shear force mentioned earlier.

[0106] 4. Optimization calculation of pile bottom embedment depth: bedrock 7 and pile shear strength Cross-sectional area of ​​pile bottom The reinforcement enhancement coefficient k=2.2. Substituting this into the optimized embedment depth formula... Calculated The actual burial depth adopted was 1.5m (adjusted based on the integrity of bedrock 7), which is 35% less than the traditional burial depth of 2.3m. This is consistent with the derivation of the k value and the burial depth optimization formula mentioned above, and verifies the feasibility of the derivation logic.

[0107] The frame beam 6 has a rectangular cross-section with dimensions of 0.4m × 0.6m, and is vertically segmented at 1.8m intervals to match the segmented excavation height (1.8m). The reinforcement densification zone 5 at the connection between the pile bottom and the bedrock 7 extends 50cm above and below the connection, with a reinforcement density 1.8 times that of the non-densification zone. The internal support 4 uses 200×200 H-beams, symmetrically and intersectingly arranged. The shotcrete layer is 12cm thick, with a concrete strength grade of C30, matching the material strength of the rotary drilling pile 1, steel pipe pile, frame beam 6, and internal support 4.

[0108] II. Construction Method Implementation Steps 1. Positioning and layout of anti-slide space units: Based on the scope of the landslide treatment area, 12 anti-slide space units are determined and laid out with a unit spacing of 3m. The positioning lines of 4 rotary drilling piles 1 in each unit are accurately laid out using a total station to ensure that the rotary drilling piles 1 are laid out with the vertices of a 4m×6m rectangle, the centroid coincides with the stress center, and the positioning deviation is controlled within ±5cm. The installation points of the inner support 4 are marked simultaneously.

[0109] 2. Construction of rotary drilling pile 1: Rotary drilling rigs are used to construct rotary drilling pile 1 according to the positioning line. During the drilling process, the verticality of the pile body is monitored in real time to ensure that the vertical deviation is not greater than 1%. After drilling to the design depth (10m), the sediment at the bottom of the hole is cleaned, a steel cage is placed and the inner support 4 connecting steel plate is pre-embedded, and concrete is poured. The concrete is poured continuously to avoid quality defects such as broken piles and mud inclusions. After the pouring is completed, curing is carried out for no less than 7 days.

[0110] 3. Construction of steel pipe piles and internal supports 4: On the rectangular outline formed by four rotary drilling piles 1, steel pipe piles are driven into the ground at 1.5m intervals between adjacent rotary drilling piles 1 using piling machinery. The driving depth of the steel pipe piles is 10m, and the pile bottom is embedded in the bedrock for 71.5m. The steel pipe piles are firmly connected to the rotary drilling piles 1 by welding. The welding quality meets the specifications and ensures that they work together to form a complete rectangular closed frame. H-shaped steel cross internal supports 4 are symmetrically installed inside the closed frame. The two ends of the internal supports 4 are fully welded to the pre-embedded steel plates of the pile body. The weld height is not less than 8mm, forming a triangular stable structure to prevent lateral deformation of the frame.

[0111] 4. Vertical segmented excavation and shotcrete protection: Using a rectangular closed frame as the boundary, vertical segmented excavation is carried out using an excavator. The segment height is controlled at 1.8m. After each segment is completed, C30 concrete is immediately sprayed onto the excavation surface, pile body, and the perimeter of the internal support using a shotcrete machine. The spray thickness is 12cm to ensure uniform coverage, no voids, and no cracks. This seals the excavation surface, reinforces the soil, and prevents soil collapse and borehole wall collapse.

[0112] 5. Layout and connection of frame beams 6: Starting from the top of the excavation, rectangular frame beams 6 are laid out at 1.8m intervals. The frame beams 6 are cast in reinforced concrete. Before casting, the pre-embedded steel bars are welded firmly to the reserved steel bars / steel plates of the rotary drilling piles 1, steel pipe piles, and internal supports 4. The welding length meets the specifications. After each section of excavation is completed, a corresponding frame beam 6 is laid out to achieve the synchronous progress of "excavation-connection" and ensure the overall rigid connection.

[0113] 6. Skip-section excavation and unit connection: The skip-section excavation method is adopted, and construction is advanced by skipping one anti-slip space unit. That is, units 1, 3, 5, 7, 9, and 11 are constructed first, followed by units 2, 4, 6, 8, 10, and 12. After the frame beams 6 of adjacent units are laid out and the concrete layer is sprayed, and the curing reaches the design strength (C30 concrete curing for 28 days), the frame beams 6 of each unit are connected by beam butt welding. The piles of each unit are connected by transverse connecting beams to ensure that the centroids of the rectangular composite components of adjacent units are aligned and the internal supports 4 are laid out synchronously, forming a continuous and complete spatial anti-slip system.

[0114] 7. Reinforcement Densification and Anchor Cable 3 Construction at the Pile Bottom Connection: At the connection between the bottom of the rotary drilling pile 1 and the steel pipe pile and the bedrock 7, reinforced steel bars are laid according to the design requirements. The reinforcement range is 50cm above and below the connection, and the reinforcement density is 1.8 times that of the non-reinforced area. Anchor cable 3 holes are drilled for the two rotary drilling piles 1 before the pile, with a hole diameter of 150mm. High-strength, low-relaxation steel strand anchor cables 3 are inserted and grouted to anchor to the stable bedrock 7. Then, prestressing is performed with a locking force of 100kN. The anchorage is sealed and protected against corrosion. After the installation is completed, the connection between the pile bottom and the bedrock 7 is grouted with cement mortar to ensure a firm connection and improve shear strength and pull-out resistance. At this time, the length of the pile body buried in the bedrock 7 is 1.5m, which is 35% less than the traditional deep burial process.

[0115] 8. Post-construction monitoring and maintenance: Throughout the construction process, displacement gauges, settlement gauges, and stress sensors will be used to monitor the horizontal displacement, vertical settlement, axial force of the internal supports (4), and prestress of the anchor cables (3) of the piles in real time. The monitoring frequency will be once a day during the excavation stage, once every 3 days during the curing stage, twice a month for the first 6 months after completion, and once a quarter thereafter. The focus will be on monitoring the deformation of the rectangular composite components, the integrity of the welds of the internal supports (4), the prestress loss of the anchor cables (3), and the stability of the pile bottom connection. If the displacement exceeds the standard or the stress is abnormal, construction will be suspended immediately and reinforcement measures will be taken. After completion, a routine maintenance mechanism will be established, with a comprehensive structural inspection conducted every year, and the moment of inertia of the components, the prestress of the anchor cables (3), the stiffness of the internal supports (4), and the shear performance of the reinforced steel reinforcement zone (5) checked every 3 years. Landslide thrust and structural stress calculations will be performed every 5 years, and rusted and loose parts will be repaired in a timely manner to extend the service life of the structure.

[0116] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention, and do not imply or require that the device or element referred to must have a specific orientation or construction method, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish the objects of description and should not be construed as limiting importance or order, and the features defined by such terms may explicitly or implicitly include one or more of those features. Unless otherwise stated, "a plurality of" in the description of this invention refers to two or more.

[0117] The terms "installation," "connection," and "joining" should be interpreted broadly, unless otherwise explicitly defined, to include, but are not limited to, fixed connections, detachable connections, or integrally formed connections; mechanical or electrical connections; direct connections or indirect connections via an intermediate medium; and internal communication between two components. Those skilled in the art can understand their meaning based on the specific technical solution. The fixed connections involved in this invention, unless otherwise stated, include both detachable fixed connections (such as bolt and screw connections) and non-detachable fixed connections (such as riveting and welding), and may also include integral structures achieved through an integral forming process (such as casting) (except where integral forming is clearly not feasible).

[0118] Unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes cover states or shapes that are similar to, close to, or adjacent to them.

[0119] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured using a one-piece molding process.

[0120] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0121] In the embodiments of this application, the same reference numerals are used to denote the same component or part.

[0122] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0123] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An anti-slip space unit, characterized by: The system includes multiple rotary drilling piles arranged according to the vertices of a polygon, and several driven piles arranged at preset intervals between adjacent rotary drilling piles. The rotary drilling piles and driven piles together form a closed frame, creating a composite component with a high moment of inertia. The rotary drilling piles on the side adjacent to the landslide body are equipped with prestressed anchor cables. The closed frame is equipped with cross-type internal supports, and the two ends of the internal supports are rigidly connected to the piles of the frame, forming a triangular stable force-bearing structure with the closed frame. The bottoms of the rotary drilling piles and driven piles are embedded in the bedrock, and a reinforced steel reinforcement zone is provided at the connection between the pile bottom and the bedrock.

2. The anti-slip space cell of claim 1, wherein, The polygon is rectangular, and there are 4 rotary drilling piles arranged at the vertices of the quadrilateral.

3. The anti-slip space cell of claim 2, wherein: The moment of inertia of the composite component is calculated and determined according to the following formula: ； ； In the formula: to synthesize the moment of inertia of the member about a horizontal axis; Let be the moment of inertia of the composite component about the vertical axis; B is the horizontal side length of the composite component; H is the vertical side length of the composite component; b is the equivalent thickness of the border post; The equivalent thickness b is calculated using a weighted average method: ； In the formula: The diameter of the rotary drilling pile; This refers to the number of rotary drilling piles on a single side; The diameter of the driven pile; This refers to the number of stakes driven into a single side. L is the length of a single side.

4. The anti-slip space unit according to claim 1, characterized in that: The prestressed anchor cables are installed with inclined tension, with an anchor cable inclination angle of 15°-30° and a prestress value of 80-150kN for a single anchor cable. One end of the anchor cable is anchored to the inner side of the pile reinforcement cage, and the other end is anchored to the stable bedrock. The cross-type internal supports are made of steel or reinforced concrete components, with an installation angle of 45°±10°, and a single set of internal supports is symmetrically installed.

5. The anti-slip space unit according to claim 1, characterized in that: The reinforced concrete zone extends at least 50cm above and below the point where the pile bottom connects to the bedrock, with a reinforcement density 1.5-2 times that of the unreinforced zone. The length of the pile bottom embedded in the bedrock is calculated using the following optimized formula: ； In the formula: V represents the total shear force at the pile bottom; The shear strength of the bedrock and the pile body; A is the cross-sectional area of ​​the pile bottom; k is the shear reinforcement enhancement factor for reinforced steel, with a value ranging from 1.8 to 2.

5.

6. The anti-slip space unit according to claim 1, characterized in that: The closed frame is vertically segmented with several layers of frame beams at preset intervals. The frame beams are rigidly connected to rotary drilling piles, driven piles, and internal supports. The surface of the spatial structure formed by the closed frame and the frame beams is sprayed with a concrete layer with a thickness of not less than 10cm.

7. An anti-slip structure, characterized in that: It includes a plurality of anti-slip space units as described in any one of claims 1 to 6, wherein the plurality of anti-slip space units are rigidly connected to form a spatial anti-slip system.

8. The anti-slip structure according to claim 7, characterized in that: Adjacent anti-slip spatial units are rigidly connected to pre-embedded connectors via transverse connecting beams or connecting plates. The centroids of each unit are aligned and the internal supports are laid out synchronously, forming a continuous and complete spatial anti-slip system.

9. A construction method based on the anti-slip structure according to claim 7 or 8, characterized in that, Includes the following steps: Preliminary survey and positioning layout to determine the parameters for the anti-slip spatial unit; Rotary pile drilling, reinforcement cage construction, and concrete pouring and curing; The driven piles are constructed and connected with the rotary drilling piles to form a closed frame. Using the closed frame as the boundary, vertically excavate in sections from top to bottom, and immediately after each section is excavated, spray concrete to seal the excavation surface and pile body; Cross-type internal support installation reinforcement; Frame beam binding and cast-in-place construction; Skip-bar excavation to excavate adjacent units and make rigid connections between units; Prestressed anchor cable construction and tensioning locking; Pile bottom reinforcement and overall acceptance.

10. The construction method according to claim 9, characterized in that: The skip-cell excavation adopts an intermittent construction method, first constructing odd-numbered anti-sliding space units, and then constructing even-numbered units after they have been cured to the design strength.

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