Cantilever anti-slide pile side pressure monitoring method

Abstract

This invention discloses a method for monitoring the lateral pressure of cantilever anti-slide piles, comprising the following steps: setting up a coordinate positioning acquisition instrument and a monitoring point calculation module; dividing the left or right side of the cantilever section of the anti-slide pile into a monitoring grid, and selecting displacement and lateral pressure monitoring points; acquiring the coordinates of the monitoring points using the coordinate positioning acquisition instrument on the ground; calculating and determining the turning point positions on the front and rear sides of the pile body using the monitoring point calculation module; determining the displacement and deflection distribution of the monitoring points based on pile deformation and the non-uniformly distributed external load characteristics of the pile-soil interface in the loaded section of the cantilever pile; and obtaining the analytical formula for fitting the lateral pressure at any point on the side of the cantilever anti-slide pile by converting the deflection of the monitoring points in the loaded section of the cantilever pile. This invention overcomes the problems of anti-slide pile breakage, slope landslides, and human error caused by unreasonable monitoring schemes or results regarding the turning point positions, pile deformation, and lateral pressure of anti-slide piles during service, as well as the complex technology, high risk, and high monitoring costs. It ensures that the rapid monitoring method is environmentally adaptable, safe to operate, simple to construct, low-cost, and highly accurate.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering, and in particular to a method for monitoring the side pressure of cantilever anti-slide piles. Background Technology

[0002] In the construction of municipal roads, highway subgrades, railway subgrades, and other transportation engineering projects, large-scale and deep excavations of soil and rock masses have resulted in numerous steep and high-altitude slopes. Under conditions of heavy rainfall, vibration, and slope loading, adverse effects such as sliding deformation of the slope soil and rock masses and overturning of reinforced structures have occurred, severely impacting the overall stability of these steep slopes. Large displacements, abrupt changes, and even deep sliding of the slope soil and rock masses have a particularly severe impact on slope stability. Numerous facts demonstrate that once large-scale landslides and collapses occur on steep slopes, repair is extremely difficult, resulting in significant property damage and casualties. Anti-slide piles, as an active reinforcement measure, play a crucial role in the reinforcement and stabilization of steep slopes. Therefore, rapid and effective displacement and pile side pressure monitoring must be implemented for cantilever pile supports on steep slopes, and timely reinforcement measures must be taken to control the occurrence of disasters.

[0003] Currently, the main tasks in measuring displacement and pile side pressure of slopes reinforced with anti-slide piles are horizontal displacement and earth pressure measurement. This is often achieved by using borehole inclinometers, steel stress gauges, and earth pressure cells to obtain the deformation and loading status of the pile-soil structure. While this method can obtain pile deformation and soil lateral pressure behind the pile, it requires pre-installing stress gauges on the pile reinforcement during pile casting and before backfilling, and then embedding earth pressure cells in the soil. However, during the service life of the anti-slide pile reinforced slope, it is difficult to obtain real-time pile side pressure distribution and its bearing reliability under conditions where the pile has already deformed. If the test results and forecasts are not timely or are misjudged, the optimal time for anti-slide pile compensation and reinforcement will inevitably be missed, leading to secondary disasters and greater losses and social impact. Therefore, real-time tracking of cantilever pile displacement and pile side pressure monitoring during service life is a technical challenge, and a simple, safe, and rapid monitoring method is still lacking. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for monitoring the side pressure of cantilever antislide piles that is environmentally adaptable, safe to operate, easy to construct, and highly accurate.

[0005] The technical solution of this invention to solve the above problems is: a method for monitoring the side pressure of a cantilever anti-slide pile, comprising the following steps:

[0006] (1) Set up the coordinate positioning acquisition instrument and the monitoring point calculation module;

[0007] (2) Divide the monitoring grid on the left or right side of the cantilever section of the anti-slide pile and select monitoring points for displacement and pile side pressure;

[0008] (3) Obtain the coordinates of the monitoring points using a ground-based coordinate positioning and data acquisition device;

[0009] (4) The turning points on the front and rear sides of the pile are determined by the monitoring point calculation module;

[0010] (5) Determine the displacement and deflection distribution of monitoring points by pile deformation and non-uniform external load characteristics of the pile-soil interface of the cantilever pile under load.

[0011] (6) Obtain the analytical formula for the lateral pressure fitting at any point on the side of the cantilever antislide pile by converting the deflection of the monitoring point of the load-bearing section of the cantilever pile.

[0012] In the above-mentioned method for monitoring the side pressure of cantilever anti-slide piles, in step (1), there are two sets of coordinate positioning acquisition instruments, which are respectively arranged at both ends of the slope range reinforced by the anti-slide piles and in areas where the ground is stable and free from deformation, and are used to capture the coordinates of the monitoring points through GPS; the monitoring point calculation module is connected to the coordinate positioning acquisition instrument and is used to calculate the coordinates and displacement of the monitoring points and to determine the position of the pile turning point by plane geometric trigonometric conversion of the pile side.

[0013] In the above-mentioned method for monitoring the side pressure of cantilever anti-slide piles, in step (2), the side of the cantilever section is divided into m×n grids, where m is the number of vertical grid divisions and n is the number of horizontal grid divisions; the grid spacing is 0.5 to 1.0 m, which is determined according to the length of the cantilever section of the anti-slide pile and the side dimensions of the pile body; the monitoring point is the side grid node, which is used to monitor the displacement of the nodes on the front and rear sides of the pile body and to calculate the side pressure of the pile.

[0014] In the above-mentioned method for monitoring the side pressure of cantilever anti-slide piles, in step (3), the location coordinates of each monitoring point are captured using GPS based on the monitoring points selected in step (2). When capturing the location coordinates, the origin of the coordinate system is set at the location of the coordinate positioning acquisition instrument on the ground, and the vertical upward and horizontal directions pointing towards the pile body from this point are the positive coordinate directions.

[0015] In the above-mentioned method for monitoring the side pressure of cantilever antislide piles, in step (4), the geometric side length and interior angle of the plane triangle on the left or right side of the pile body are obtained by coordinate conversion based on the coordinates of the monitoring point in step (3), and the distance from the pile body turning point to the inner and outer boundary line nodes of the monitoring grid is obtained by the sine theorem, and the position of the pile body turning point is determined.

[0016] The distance AP from the pile turning point to the outer boundary node of the monitoring grid:

[0017]

[0018] in,

[0019] The distance BP' from the pile turning point to the boundary node within the monitoring grid:

[0020]

[0021] In the formula: A' is the point after deformation of grid node A, B' is the point after deformation of grid node B, AP is the distance from the pile turning point to the outer boundary node of the monitoring grid, BP' is the distance from the pile turning point to the inner boundary node of the monitoring grid, and x... A and y A To monitor the coordinates of monitoring point A on the outer boundary line of the grid, x A＇ and y A＇ Let x be the coordinates of point A'. B and y B To monitor the coordinates of monitoring point B on the boundary line within the grid, x B＇ and y B＇ Let B' be the coordinates, AA' be the displacement of mesh node A before and after deformation, BB' be the displacement of mesh node B before and after deformation, ∠APA' and ∠AA'P be the interior angles of triangle ΔAA'P, and ∠BB'P' and ∠BP'B' be the interior angles of triangle ΔBB'P'.

[0022] In the above-mentioned method for monitoring the side pressure of cantilever anti-slide piles, in step (5), the displacement is calculated by the monitoring point calculation module based on the coordinates of the monitoring points obtained in step (3) to obtain the deflection of the boundary line nodes within the monitoring grid:

[0023]

[0024] Where q(y)=ay 2 +by+c, where a, b, and c are the coefficients of the analytical formula fitting the side pressure of the cantilever anti-slide pile; μ(y i ) represents monitoring point y i The deflection at the location, i = 1, 2…m; EI is the bending stiffness of the anti-slide pile, q(y) is the side pressure of the anti-slide pile, y i Let y be the vertical coordinates of the i-th monitoring point in the vertical grid on the pile side and any point on the pile side, respectively. L0 This is the length from the top of the pile to the turning point.

[0025] In the above-mentioned method for monitoring the side pressure of cantilever anti-slide piles, in step (6), the load-bearing section of the cantilever pile is the part above the pile turning point; based on the deflection of the monitoring points of the boundary line in the grid in step (5), combined with the non-uniform distribution of external loads at the pile-soil interface of the load-bearing section, the coefficients of the fitting analytical expression of the side pressure at any point on the side of the cantilever anti-slide pile are calculated using the least squares method, and the side pressure distribution at any point on the side of the cantilever anti-slide pile can be obtained.

[0026] Let q(y) = ay 2 Substituting +by+c into equation (3), we get:

[0027]

[0028] Let y = y1, μ = μ(y i );y=y2,μ=μ(y2);…y=y m μ=μ(y m Substituting into equation (4), the coefficients of the fitting analytical expression for the lateral pressure at any point on the pile side are obtained using the least squares method:

[0029] q(y)=a0y 2 +b0y+c0

[0030] Furthermore, the analytical formula for fitting the lateral pressure at any point on the pile side is obtained.

[0031]

[0032] In the formula: a0, b0, c0 are the coefficients of the analytical expression fitting the lateral pressure at any point on the pile side.

[0033] The beneficial effects of this invention are as follows:

[0034] 1. The method of this invention can overcome the problems of anti-slide pile fracture, slope landslide and human error caused by unreasonable monitoring schemes or monitoring results of anti-slide pile rotation point location, pile deformation and pile side pressure during service, as well as technical complexity, high risk and high monitoring cost. It ensures that the rapid monitoring method has strong environmental adaptability, safe operation, simple construction, low cost and high accuracy. It can also provide timely feedback and long-term monitoring of pile deformation and pile side pressure distribution, thereby evaluating the bearing stability of the pile and actively controlling the overall instability and failure of the slope reinforced by anti-slide piles.

[0035] 2. Based on the real-time distribution and monitoring data of the cantilever anti-slide pile turning point, pile deformation, and pile side pressure, it can be seen that the on-site monitoring method for the cantilever anti-slide pile side pressure of this invention provides the time for pile bearing stability and timely compensation and reinforcement, giving full play to the timeliness of the monitoring data. It has good theoretical significance and economic and social value for quickly identifying and actively reinforcing the safe bearing capacity of the pile and the overall stability of the slope. Attached Figure Description

[0036] Figure 1 This is a flowchart of the method of the present invention.

[0037] Figure 2 This is a schematic diagram of the grid division of the cantilever pile and the arrangement of the pile side pressure monitoring device of the present invention.

[0038] Figure 3 This is a schematic diagram illustrating the calculation of the pivot point position of a cantilever pile according to an embodiment of the present invention.

[0039] Figure 4 This is a schematic diagram illustrating the calculation of deflection (horizontal displacement) and lateral pressure at monitoring points within the grid of a cantilever pile according to an embodiment of the present invention.

[0040] In the figure, 1 is the ground, 2 is the coordinate positioning acquisition instrument A (B), 3 is the slope, 4 is the sliding surface, 5 is the platform, 6 is the retaining plate, 7 is the anti-slide pile, 8 is the grid, 9 is the outer boundary line, 10 is the inner boundary line, 11 is the load-bearing section, 12 is the turning point, 13 is the monitoring point calculation module, and 14 is the monitoring point. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] See Figures 1 to 4 In this embodiment, the slope reinforced by cantilever piles is a soil slope with a reinforcement width of 50m. The concrete grade of the anti-slide piles is C30, and the bending stiffness EI = 52 × 10⁻⁶. 9 N·m 2 The pile body has a cross-sectional dimension of 2.5×2.0m, a pile spacing of 6m, a retaining plate is installed between the piles, the pile length is 20m, of which the load-bearing section is 12m long, the anchorage section is 8m long, the width of the pile top platform is 2m, and the lateral pressure distribution q (kN / m) behind the pile is a non-uniformly distributed load.

[0043] A method for monitoring the side pressure of a cantilever anti-slide pile includes the following steps:

[0044] (1) Set up coordinate positioning acquisition instrument 2 and monitoring point calculation module 13.

[0045] The coordinate positioning acquisition device 2 consists of two sets, A and B, which are respectively arranged at both ends of the slope 3 reinforced by the anti-slide pile 7 and in the stable and deformation-free area of ​​the ground 1. They are used to capture the coordinates of the monitoring point through GPS. The monitoring point calculation module 13 is connected to the coordinate positioning acquisition device 2 and is used to calculate the coordinates and displacement of the monitoring point and to determine the position of the pile turning point by plane geometric trigonometric conversion of the pile side.

[0046] (2) Divide the monitoring grid 8 on the left or right side of the cantilever section of the anti-slide pile 7, and select the displacement and pile side pressure monitoring points 14.

[0047] The side of the cantilever section is divided into 12×2 grids. The vertical number of grid 8 is 12, the horizontal number of grid 8 is 2, the vertical spacing of grid 8 is 1.0m, and the horizontal spacing of grid 8 is 1.0m. Monitoring point 14 is a side grid node, used to monitor the displacement of the nodes on the front and rear sides of the pile (the boundary node of side monitoring grid 8) and to calculate the pile side pressure.

[0048] (3) Obtain the coordinates of the monitoring point through the coordinate positioning and acquisition instrument B on the ground 1.

[0049] According to the monitoring point 14 selected in step (2), the coordinate positioning acquisition instrument B is arranged at both ends of the slope 3 reinforced by the anti-slide pile 7, and the ground 1 is in a stable and deformation-free area; GPS is used to capture the position coordinates of each monitoring point 14; when capturing the position coordinates, the origin of the coordinate system is set at the ground 1 where the coordinate positioning acquisition instrument is located, and the vertical upward and horizontal directions from this point are the positive coordinate directions.

[0050] (4) The position of the turning point 12 on the front and rear sides of the pile body is determined by the monitoring point calculation module 13.

[0051] Based on the coordinates of monitoring point 14 in step (3), the geometric side length and interior angle of the plane triangle on the left or right side of the pile body are obtained by coordinate conversion. Then, the distance from the pile body turning point 12 to the inner and outer boundary line nodes of the monitoring grid is obtained by the sine theorem, and the position of the pile body turning point 12 is determined.

[0052] The distance AP from pile pivot point 12 to node 9 of the outer boundary line of the monitoring grid:

[0053]

[0054] in,

[0055] The distance BP' from pile pivot point 12 to node 10 of the monitoring grid boundary:

[0056]

[0057] Where A' is the point after deformation of grid node A, B' is the point after deformation of grid node B, AP is the distance from the pile rotation point to the outer boundary node of the monitoring grid, BP' is the distance from the pile rotation point to the inner boundary node of the monitoring grid, and x A and y A To monitor the coordinates of monitoring point A on the outer boundary line of the grid, x A＇ and y A＇ Let x be the coordinates of point A'. B and y B To monitor the coordinates of monitoring point B on the boundary line within the grid, x B＇ and y B＇ Let B' be the coordinates, AA' be the displacement of mesh node A before and after deformation, BB' be the displacement of mesh node B before and after deformation, ∠APA' and ∠AA'P be the interior angles of triangle ΔAA'P, and ∠BB'P' and ∠BP'B' be the interior angles of triangle ΔBB'P'.

[0058] (5) The displacement and disturbance distribution of monitoring point 14 were determined by the pile deformation and the non-uniform external load characteristics of the pile-soil interface of the cantilever pile loading section 11.

[0059] Based on the monitoring point coordinates obtained in step (3), the displacement is calculated using the monitoring point calculation module 13 to obtain the deflection of the boundary line 10 nodes within the monitoring grid 8:

[0060]

[0061] Where q(y)=ay 2 +by+c, where a, b, and c are the coefficients of the analytical formula fitting the side pressure of the cantilever anti-slide pile; μ(y i ) represents monitoring point y i The deflection at the location, i = 1, 2…m; EI is the bending stiffness of the anti-slide pile, q(y) is the side pressure of the anti-slide pile, y i Let y be the vertical coordinates of the i-th monitoring point in the vertical grid on the pile side and any point on the pile side, respectively. L0 This is the length from the top of the pile to the turning point.

[0062] (6) The analytical formula for the lateral pressure fitting at any point on the side of the cantilever antislide pile 7 is obtained by converting the deflection of monitoring point 14 on the load-bearing section 11 of the cantilever pile (the part above the pile body turning point 12).

[0063] Based on the deflection of monitoring point 14 of the grid boundary line 10 in step (5), combined with the non-uniform external load distribution of the pile-soil interface of the loaded section 11, the coefficients of the fitting analytical expression of the lateral pressure at any point on the side of the cantilever anti-slide pile 7 can be obtained by using the least squares method.

[0064] Let q(y) = ay 2 Substituting +by+c into equation (3), we get:

[0065]

[0066] Let y = y1, μ = μ(y i );y=y2,μ=μ(y2);…y=y m , μ=μ(y m Substituting into equation (4), the coefficients of the fitting analytical expression for the lateral pressure at any point on the pile side are obtained using the least squares method:

[0067] q(y)=a0y 2 +b0y+c0

[0068] Furthermore, the analytical formula for fitting the lateral pressure at any point on the pile side is obtained.

[0069]

[0070] In the formula: a0, b0, c0 are the coefficients of the analytical expression fitting the lateral pressure at any point on the pile side.

Claims

1. A method for monitoring the side pressure of a cantilever anti-slide pile, characterized in that, Includes the following steps: (1) Set up the coordinate positioning acquisition instrument and the monitoring point calculation module; (2) Divide the monitoring grid on the left or right side of the cantilever section of the anti-slide pile, and select monitoring points for displacement and pile side pressure; (3) Obtain the coordinates of the monitoring points using a ground-based coordinate positioning and data acquisition instrument; (4) The turning points on the front and rear sides of the pile are determined by the monitoring point calculation module; (5) Determine the displacement and deflection distribution of monitoring points by the pile deformation and the non-uniformly distributed external load characteristics of the pile-soil interface in the loaded section of the cantilever pile; (6) Obtain the analytical formula for the lateral pressure fitting at any point on the side of the cantilever antislide pile by converting the deflection of the monitoring point of the load-bearing section of the cantilever pile.

2. The method for monitoring the side pressure of cantilever anti-slide piles according to claim 1, characterized in that, In step (1), there are two sets of coordinate positioning acquisition instruments, which are respectively arranged at both ends of the slope range reinforced by anti-slide piles and in areas where the ground is stable and free from deformation. They are used to capture the coordinates of the monitoring points through GPS. The monitoring point calculation module is connected to the coordinate positioning acquisition instrument and is used to calculate the coordinates and displacement of the monitoring points and to determine the position of the pile turning point by plane geometric trigonometric conversion of the pile side.

3. The method for monitoring the side pressure of cantilever anti-slide piles according to claim 1, characterized in that, In step (2), the side of the cantilever section is divided into m×n grids, where m is the number of vertical grid divisions and n is the number of horizontal grid divisions. The grid spacing is 0.5~1.0m, which is determined according to the length of the cantilever section of the anti-slide pile and the side dimensions of the pile body. The monitoring points are the side grid nodes, which are used to monitor the displacement of the nodes on the front and rear sides of the pile body and to calculate the pile side pressure.

4. The method for monitoring the side pressure of cantilever anti-slide piles according to claim 1, characterized in that, In step (3), GPS is used to capture the position coordinates of each monitoring point selected in step (2). When capturing the position coordinates, the origin of the coordinate system is set at the ground position of the coordinate positioning acquisition instrument, and the vertical upward and horizontal directions from this point are the positive coordinate directions.

5. The method for monitoring the side pressure of cantilever anti-slide piles according to claim 1, characterized in that, In step (4), based on the coordinates of the monitoring point in step (3), the geometric side length and interior angle of the plane triangle on the left or right side of the pile body are obtained by coordinate conversion, and then the distance from the pile body turning point to the inner and outer boundary line nodes of the monitoring grid is obtained by the sine theorem, thus determining the position of the pile body turning point; Distance from the pile turning point to the outer boundary node of the monitoring grid : （1）; in, ; Distance from the pile turning point to the boundary node within the monitoring grid : （2）; in, ; In the formula: For grid nodes The deformed point, For grid nodes The deformed point, This is the distance from the pile turning point to the outer boundary node of the monitoring grid. This is the distance from the pile turning point to the boundary line node within the monitoring grid. and To monitor the outer boundary line monitoring points of the grid coordinates and for The coordinates of the point and To monitor the boundary line monitoring points within the grid coordinates and for The coordinates of the point For grid nodes Displacement before and after deformation For grid nodes Displacement before and after deformation and It is a triangle interior angle, and It is a triangle inner angle.

6. The method for monitoring the side pressure of cantilever anti-slide piles according to claim 1, characterized in that, In step (5), based on the coordinates of the monitoring points obtained in step (3), displacement calculation is performed using the monitoring point calculation module to obtain the deflection of the boundary line nodes within the monitoring grid: （3）; in, , , , The coefficients are the fitting analytical expression coefficients for the side pressure of the cantilever anti-slide pile. For monitoring points The disturbance at the location, ; To improve the bending stiffness of the anti-slide piles, To prevent the lateral pressure of the anti-slide piles, , The vertical grid on the pile side is respectively the first The vertical coordinates of the monitoring point and any point on the side of the pile. This is the length from the top of the pile to the turning point.

7. The method for monitoring the side pressure of cantilever anti-slide piles according to claim 6, characterized in that, In step (6), the load-bearing section of the cantilever pile is the part above the pile turning point; based on the deflection of the monitoring point of the boundary line in the grid in step (5), combined with the non-uniform external load distribution of the pile-soil interface in the load-bearing section, the coefficients of the fitting analytical expression of the lateral pressure at any point on the side of the cantilever anti-slide pile are calculated by the least squares method, and the lateral pressure distribution at any point on the side of the cantilever anti-slide pile can be obtained. Will Substituting into equation (3), we get: （4）; Will , ; , ;... , Substituting into equation (4), the coefficients of the fitting analytical expression for the lateral pressure at any point on the pile side are obtained by the least squares method: ; Further, the analytical formula for fitting the lateral pressure at any point on the pile side is obtained. (5); In the formula: , , The coefficients are the fitting equations for the lateral pressure at any point on the pile side.

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