Sheet pile displacement measurement and correction calculation method considering base point displacement

Abstract

The invention relates to a sheet pile displacement measurement and correction calculation method considering base point displacement, and the method is simple in principle and accurate in measurement and calculation result, and can solve the problems that obstacles exist near a bank slope, a fixed base point cannot be found, the bank slope is deformed, and the base point is located in a bank slope deformation area and can be displaced. And displacement of the bank protection sheet pile can be accurately measured. Firstly, a monitoring point is selected on a sheet pile, two pull rope type displacement sensors are installed, then two base points are selected on a nearby bank slope, one base point is a conventional base point and can be made by a steel chisel, and the other base point is a newly-added base point and can be made by an inclinometer pipe. Finally, the two pull rope type displacement sensors are connected with the two base points through steel wire ropes respectively, and the two base points are connected through steel bars. When the sheet pile generates displacement, the two base points also generate displacement, and the actually generated displacement of the sheet pile is calculated by measuring the distance between the sheet pile displacement monitoring points and the two base points before and after displacement and the monitoring values of the inclinometer tubes before and after the base points generate displacement and further through the plane position relation between the sheet pile displacement monitoring points and the two base points.

Description

Technical Field

[0001] This invention relates to a method for measuring and correcting sheet pile displacement considering base point displacement, particularly applicable to the field where there are obstacles around the waterway bank slope, the distance between the revetment sheet pile and the base point is short, and the bank slope displacement deformation causes the base point to shift. The method uses dual base point measurement and correction to calculate the sheet pile displacement. Background Technology

[0002] Waterways are crucial infrastructure supporting the development of integrated transportation systems and socio-economic development. Waterway revetments serve as the protective line for waterways, ensuring their safety. Waterway slopes are prone to lateral slippage, consolidation settlement, and uneven settlement, which can lead to slope collapse or even complete damage to the revetment. Revetment structures refer to engineering measures used to artificially reinforce riverbanks to protect them from wave, current, groundwater, and other forms of damage, maintaining slope stability. Revetment structures play a vital role in protecting riverbanks.

[0003] Sheet pile revetments are a common and widely used type of revetment structure, serving to prevent river erosion, protect riverbanks, and reinforce them. Sheet pile revetments are durable, provide significant engineering reinforcement, are easy to construct, and are environmentally friendly. However, due to factors such as channel dredging and pressure from nearby buildings, sheet piles can shift, potentially leading to bank instability and building damage. Therefore, monitoring sheet pile displacement is crucial. The conventional method for measuring sheet pile displacement involves finding a fixed, stationary point near the monitoring point as a baseline. This baseline typically does not shift. A point on the sheet pile is selected as the monitoring point, and a wire-type displacement sensor is installed at this point. The sensor is connected to the baseline via a steel wire rope. When the sheet pile shifts, the length of the steel wire rope changes, allowing the displacement to be read by the wire-type displacement sensor. If conditions are limited and the distance between the benchmark and the monitoring point is close, when the channel is excavated, the soil at the benchmark will also shift at the same time as the sheet pile shifts. The change in the length of the steel wire rope between the monitoring point and the benchmark is not equal to the displacement of the sheet pile. This will cause measurement errors and affect the monitoring results. Therefore, a sheet pile displacement correction measurement method that takes into account the displacement of the benchmark is needed.

[0004] A method for measuring and correcting sheet pile displacement considering base point displacement is proposed. This method is simple in principle and provides accurate measurement and calculation results. It can solve the problem of accurate displacement measurement of revetment sheet piles in situations where there are obstacles near the bank slope, the base point cannot be found, the bank slope is deformed, or the base point is located in the deformation area of ​​the bank slope and will be displaced. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for measuring and correcting sheet pile displacement considering base point displacement. The method first selects a monitoring point on the sheet pile and installs two rope-type displacement sensors. Then, two base points are selected on a nearby bank slope. One base point is a conventional base point, which can be constructed using steel rods, while the other is a newly added base point, which can be constructed using inclinometer tubes. Finally, the two rope-type displacement sensors are connected to the two base points respectively using steel wire ropes, and the two base points are connected by reinforcing bars. When the sheet pile displaces, the two base points also displace simultaneously. By measuring the distance between the sheet pile displacement monitoring point and the two base points before and after displacement, as well as the inclinometer tube monitoring values ​​before and after base point displacement, the actual displacement of the sheet pile is calculated based on the planar positional relationship between the sheet pile displacement monitoring point and the two base points.

[0006] The technical solution adopted in this invention is as follows:

[0007] According to the monitoring plan, the monitoring location is selected on the revetment sheet piles. Since the sheet piles (including the cap beams at the top of the sheet piles) are generally located underwater, it is impossible to directly monitor the displacement. Therefore, vertical steel bars are pre-embedded on the cap beams, with the upper part of the steel bars protruding above the water surface. The top of the steel bars is used as the sheet pile displacement monitoring point.

[0008] The sheet pile displacement monitoring point is adjacent to the deep soil displacement (inclinometer monitoring) monitoring point on the bank slope. The top elevation of the inclinometer tube at the sheet pile displacement monitoring point and the deep soil displacement monitoring point is the same, and the line connecting the sheet pile displacement monitoring point and the top of the inclinometer tube is perpendicular to the channel shoreline.

[0009] Two pull-rope displacement sensors are placed at the same sheet pile displacement monitoring point, with the two pull-rope displacement sensors close together.

[0010] Two base points are set up. The inclinometer tube at the deep soil displacement monitoring point is used as base point B. A base point C is set up between the sheet pile displacement monitoring point A and the deep soil displacement monitoring point B. A short steel rod is inserted into the bank slope soil at base point C. The top of the steel rod is at the same elevation as the top of the sheet pile displacement monitoring point and the top of the inclinometer tube. The three points, sheet pile displacement monitoring point A, base point B, and base point C, are on a straight line.

[0011] The ends of the steel wire ropes of the two pull-rope displacement sensors at the sheet pile displacement monitoring point are connected and fixed to base point B and base point C respectively. Base point B and base point C are connected by welding steel bars.

[0012] Before the sheet pile displacement occurs, the distance L between base point B and base point C, and the distance L1 between base point C and sheet pile displacement monitoring point A are measured, and the initial values ​​of the two rope-type displacement sensors and the deep soil displacement sensor are recorded.

[0013] Two pull-rope displacement sensors and a deep soil displacement sensor are activated. When the sheet pile is displaced, the pull-rope displacement sensor and the deep soil displacement sensor can measure and record relevant data in real time.

[0014] Based on the planar positional relationship between the sheet pile displacement monitoring points A, B, and C before and after the displacement, and the relevant measurement data, calculate the actual horizontal displacement of the sheet pile displacement monitoring point A.

[0015] The horizontal displacement of the top cap beam of the sheet pile is calculated based on the actual horizontal displacement of the sheet pile at monitoring point A. The horizontal displacement of the cap beam is the actual horizontal displacement of the sheet pile.

[0016] Compared with the existing single-base-point rope displacement measurement method, this invention uses a double-base-point method to measure sheet pile displacement. It also uses the inclinometer tube in deep soil displacement monitoring as a base point to measure and correct the sheet pile displacement, thereby obtaining a more accurate and true sheet pile displacement for revetment. Attached Figure Description

[0017] Figure 1 This is a plan view of the method of the present invention;

[0018] Figure 2 This is a cross-sectional view of the method of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings;

[0020] Complete the sheet pile displacement monitoring and measurement setup according to the layout shown in the attached drawings and the description in the invention.

[0021] Before the sheet pile displacement, the distance between base point B and base point C is L, and the distance between base point C and sheet pile monitoring point A is L1;

[0022] The waterway is divided into n segments along its direction. After each segment is excavated, the sheet piles will be displaced. The displacement of the sheet piles ends after all n segments of the waterway have been excavated.

[0023] During the channel excavation process, sheet piles in the excavated area were displaced, while those in the unexcavated area were not displaced. At the boundary between the excavated and unexcavated areas, the sheet pile displacement was more complex, with the sheet piles experiencing displacements perpendicular to and parallel to the channel direction.

[0024] For sheet pile monitoring points, the displacement can be divided into two parts: the displacement u perpendicular to the direction of the waterway (along the y-axis) and the displacement h parallel to the direction of the waterway (along the x-axis).

[0025] After the channel was excavated, the slope soil also shifted. The displacement of base point B along the y-axis is u1, and the displacement along the x-axis is h1. The displacement of base point C along the y-axis is u2, and the displacement along the x-axis is h2.

[0026] Base point B is a deep soil displacement monitoring point. The displacement generated by base point B along the y-axis is u1, and the displacement generated along the x-axis is h1, which are the monitoring values ​​of the inclinometer tube in the y and x directions, respectively.

[0027] The distance L+L1 between A and B before the displacement of the sheet pile and the bank slope soil becomes the distance S1 between A' and B' after the displacement. The distance L1 between A and C before the displacement of the sheet pile and the bank slope soil becomes the distance S2 between A' and C' after the displacement. The values ​​of S1 and S2 can be directly obtained from the changes in the values ​​monitored by the two rope-type displacement sensors at monitoring point A.

[0028] Base point B and base point C are connected by short steel bars. The deformation of the slope soil has a small force on the steel bars. Since the elastic modulus of the steel bars is large and the elastic modulus of the slope soil is relatively small, the change in distance between base point B and base point C can be ignored during the deformation of the slope soil. Therefore, when base point B and base point C are displaced to base point B' and base point C', the distance between base point B' and base point C' is still L.

[0029] Taking base point B as the origin, after the slope soil deforms, the coordinates of base point B' are (-h1, u1), and the coordinates of base point C' are (-h2, L+u2). Since the distance between base point B' and base point C' remains L, we can conclude that:

[0030] Before the sheet pile displacement, the coordinates of monitoring point A are (0, L+L1), and after the sheet pile displacement, the coordinates of monitoring point A' are (-h, L+L1+u).

[0031] The distance between the sheet pile monitoring point A' and the base point B' is S1. From this, we can obtain:

[0032] The distance between the sheet pile monitoring point A' and the base point C' is S2. Therefore, we can obtain:

[0033] Based on the research findings of some scholars on the variation law of horizontal displacement of the soil outside the foundation pit under cantilever support, the horizontal displacement of the soil outside the pit can be expressed as: u0 represents the horizontal displacement of any point on the slope surface, y' represents the horizontal distance between the soil at any point on the slope and the sheet pile monitoring point along the y-axis, H represents the length of the sheet pile, and H1 represents the vertical distance between the top surface of the sheet pile cap beam and the monitoring point. From the expression for the horizontal displacement of the soil outside the pit, it can be seen that there is a linear relationship between the horizontal displacement of the slope soil and the horizontal displacement of the sheet pile monitoring point. Therefore:

[0034] Joint equations and The displacements u2 and h2 of the base point C, and the displacements u and h of the sheet pile monitoring point A can be solved using a mathematical solver or programming. In the formula, L, L1, S1, S2, u1, h1, H, and H1 can be obtained from design data and monitoring data.

[0035] After obtaining the horizontal displacement u at the sheet pile monitoring point, assuming that the sheet pile displacement changes linearly along the pile body and is 0 at the pile bottom, the actual horizontal displacement of the sheet pile (top surface of the cap beam) can be obtained:

Claims

1. A method for measuring and correcting sheet pile displacement considering base point displacement, characterized in that... The principle is simple, and the measurement and calculation results are accurate. It can solve the problem of accurately measuring the displacement of revetment sheet piles in situations where there are obstacles near the bank slope, it is impossible to find a stationary benchmark, the bank slope is deformed, or the benchmark is located in the deformed area of ​​the bank slope and will displace. The steps include: S1: Pre-embed vertical steel bars on the sheet pile cap beam so that the upper part of the steel bars protrudes above the water surface. Use the top of the steel bars as the sheet pile displacement monitoring point A. Arrange two rope-type displacement sensors at monitoring point A and place them close together. S2: Use inclinometer tubes to monitor the displacement of deep soil on the bank slope, and use the top of the inclinometer tube as the base point B; S3: Sheet pile displacement monitoring point A is adjacent to the base point B at the top of the inclinometer tube, ensuring that the two have the same elevation and that the line connecting the two is perpendicular to the waterway shoreline. S4: A base point C is set up between the sheet pile displacement monitoring point A and the base point B at the top of the inclinometer tube. A short steel rod is inserted into the slope soil at base point C, and the elevation is the same as that of the sheet pile displacement monitoring point A and the base point B at the top of the inclinometer tube, so as to ensure that the three points A, B and C are on a straight line. S5: The ends of the steel wire ropes of the two pull rope displacement sensors at the sheet pile displacement monitoring point A are fixedly connected to the base points B and C respectively. The connection between the base points B and C is made by welding steel bars. S6: Before the sheet piles are displaced, measure the distance L between base point B and base point C, and the distance L1 between base point C and sheet pile displacement monitoring point A, and record the initial values ​​of the two rope-type displacement sensors and the deep soil displacement sensor of the bank slope. S7: Turn on the data acquisition device of the two pull-rope displacement sensors and the deep soil displacement sensor. When the sheet pile is displaced, the pull-rope displacement sensor and the deep soil displacement sensor can measure and record relevant data in real time. S8: Based on the planar positional relationship between monitoring point A, base point B and base point C before and after the sheet pile displacement and the relevant measurement data, calculate the actual horizontal displacement of monitoring point A of the sheet pile displacement; S9: Calculate the horizontal displacement of the top cap beam of the sheet pile based on the actual horizontal displacement of the sheet pile displacement monitoring point A. The horizontal displacement of the cap beam is the actual horizontal displacement of the sheet pile. S10: Finally, combining the monitored data and parameters in the design documents, use a mathematical solver or programming to solve for the displacement of the base point C and the displacement of the sheet pile monitoring point A; S11: After obtaining the horizontal displacement of the sheet pile monitoring point, it is assumed that the sheet pile displacement changes linearly along the pile body, and the displacement at the bottom of the pile is 0. Then the actual horizontal displacement of the sheet pile (top surface of the cap beam) can be obtained.

2. The sheet pile displacement measurement method as described in claim 1, characterized in that... Compared with the existing single-baseline rope displacement measurement method, this method uses double baselines to measure sheet pile displacement. It also uses inclinometer tubes in deep soil displacement monitoring as baselines to measure and correct sheet pile displacement, thus obtaining more accurate and true sheet pile displacement for revetment.

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