Steel sheet pile joint sealing performance in-situ detection process and monitoring method

Abstract

The invention belongs to the technical field of foundation pit supporting, and particularly relates to a steel sheet pile joint sealing performance in-situ detection process and a monitoring method. Through the cooperative design of the embedded pipe and the detection hole, the embedded pipe is filled with the liquid reagent, and if leakage happens to the joint of the steel sheet pile, the solid reagent in the detection hole can make contact with the liquid reagent to change color. Leaking stoppage is carried out after the color changing position is detected, and long-term monitoring is carried out by monitoring the soil body index of the leaking position so as to be used as a supplement of a detection process. The problem of ex-situ detection of steel sheet pile joint leakage and the problem of difficulty in leaking stoppage are solved, and the normal function of the steel sheet pile under the long-term working condition can be guaranteed.

Description

Technical Field

[0001] This application belongs to the field of foundation pit support technology, specifically relating to an in-situ testing process and monitoring method for the sealing performance of steel sheet pile joints. Background Technology

[0002] Sheet piles are a type of steel structure with interlocking joints used in engineering construction to form continuous and tight retaining walls or water-retaining walls. As a steel structure, sheet piles can effectively resist horizontal earth pressure and water pressure after forming a continuous support structure. Therefore, the safety and stability of sheet piles are of great significance to engineering construction.

[0003] There are many common steel sheet pile cross-sectional forms and various construction methods. However, regardless of the type of steel sheet pile or construction method, the verticality and interlocking degree of the steel sheet pile are the core issues that must be paid attention to during construction. However, in actual construction, the existing construction technology has the following problems: (1) Due to the difference in the labor level of workers, if the sealing material used at the joint is inappropriate or the welding technology is substandard, the steel sheet pile is prone to joint gaps and water leakage. (2) Due to the difficulty in confirming the undulation of the ground surface, it is difficult to ensure that the bottom of the steel sheet pile is tightly interlocked with the ground surface during construction. Moreover, during the process of inserting the steel sheet pile into the stratum, the center of the steel sheet pile may be deviated, which aggravates the problem of poor splicing at the bottom of the steel sheet pile, resulting in water leakage. (3) At present, there are few technologies that can repair the leakage of deep steel sheet piles. If monitoring is lacking, it will affect construction safety, project quality and construction progress. (4) There is a lack of efficient testing and long-term monitoring and evaluation methods for the sealing performance of steel sheet pile joints, which leads to the evaluation of joint sealing performance mainly relying on manual experience and lacking scientific rigor. Summary of the Invention

[0004] This application provides an in-situ testing process for the sealing performance of sheet pile joints, which solves the problem of non-in-situ detection of leakage in sheet pile joints.

[0005] The technical solution of this application is as follows: An in-situ testing process for the sealing performance of steel sheet pile joints includes the following steps: Step 1: Fix a pre-embedded pipe along the entire length of the soil-facing side of the steel sheet pile. The pre-embedded pipe has several openings distributed along its height. Step 2: Install the combined structure of steel sheet piles and embedded pipes at the reserved positions of the steel sheet piles; Step 3: Drill a test hole vertically downwards from the ground surface on the side of the foundation pit of the steel sheet pile. The depth of the test hole is equal to the length of the steel sheet pile. Step 4: Place a probe tube within the full depth of the detection hole. The probe tube has a filter-like tube wall and a core coated with a solid reagent.

[0006] Step 5: According to the target detection depth, liquid reagent is injected into the pre-embedded pipe in stages from bottom to top using a grouting pump. The liquid reagent causes the solid reagent to change color after contacting with it. Step Six: Remove the core tube and mark the location of the leakage as the corresponding depth of the sheet pile at the discoloration point. Seal the leakage location.

[0007] Furthermore, the openings are evenly spaced along the height, and there are two openings at each height, each facing the seam.

[0008] Furthermore, the solid reagent is phenolphthalein powder, and the liquid reagent is an alkaline reagent.

[0009] Furthermore, the sealing method in step six is ​​as follows: inject quick-setting water-blocking material into the pre-embedded pipe opening at the leakage location and into the adjacent openings above and below the pre-embedded pipe opening.

[0010] Furthermore, when there are two or more leakage points, inject quick-setting plugging material into each opening in a bottom-up order.

[0011] Furthermore, the core has several segmented core units, and the upper end of each core unit is provided with an isolation pad.

[0012] This application also provides a method for monitoring the sealing performance of steel sheet pile joints, including the following steps: S1. Measure the pore water pressure at the leakage location on the soil-facing side of the sheet pile where leakage has occurred. Horizontal displacement of pile body and pile side earth pressure ; S2. Measure the pore water pressure at the depth corresponding to the leakage location of the non-leaking sheet pile and the leaking sheet pile. Horizontal displacement of pile body and pile side earth pressure ; S3, based on and Establish pore water pressure monitoring indicators : ; based on and Establish monitoring indicators for horizontal displacement of pile body : ; based on and Calculate the monitoring index of earth pressure on pile side : ; S4, based on , , Evaluation indices for the sealing performance of steel sheet piles were calculated using the weighted analysis method. The allowable value [K] for the evaluation index of the sealing performance of sheet piles is set. When K is less than [K], the sealing performance of sheet piles is judged to meet the requirements. When K is greater than or equal to [K], the sealing performance of sheet piles is judged to not meet the requirements.

[0013] Furthermore, in S2, on each side of the sheet pile that has leaked, a sheet pile that is closest to it and has no leakage is selected to measure its leakage rate. , as well as The average value is then taken as the calculated value of the monitoring indicator.

[0014] Due to the adoption of the above technical solution, the beneficial effects of this application are as follows: 1. When the verticality of the sheet pile is insufficient or there are defects in the joint itself, pores will form at the joint, creating conditions for leakage. This application uses a grouting pump to control the injection pressure of the liquid reagent, allowing it to diffuse through the opening to the detection hole and come into contact with the solid reagent. The location of the leakage is determined by the color change of the solid reagent. The detection point must be less than the excavation depth of the foundation pit. Due to the presence of groundwater, the water pressure at the detection point depth will exert pressure on the liquid reagent, guiding the reagent to penetrate into the foundation pit. Therefore, if leakage occurs, the color change of the solid reagent can be observed on the other side of the sheet pile. In this application, leakage detection is carried out in stages from bottom to top. This effectively avoids the downward seepage of the liquid reagent interfering with the determination of the results when leakage occurs in shallower areas.

[0015] 2. This application designs a pre-embedded pipe, which can be used for both in-situ detection of leakage locations and for sealing leaks when they occur. Through the opening in the pre-embedded pipe, the leakage location can be accurately located, and quick-setting sealing material can be filled quickly and precisely.

[0016] 3. The steel sheet pile sealing performance testing method of this application is an on-site in-situ testing method, which can accurately reflect the on-site steel sheet pile construction quality, sealing performance and leakage point location, improve the scientificity, efficiency and convenience of steel sheet pile support construction quality testing, effectively overcome the shortcomings of traditional human experience judgment methods, and overcome the shortcomings of traditional concealed construction quality that is difficult to scientifically test.

[0017] 4. The monitoring method in this application is based on the testing process and utilizes the structure of the pre-embedded pipe to measure parameters in the soil. Furthermore, the parameters used for comparison are also measured territorially, providing a more accurate reflection of the soil condition. As a supplement to the testing process, the monitoring method quantifies the long-term sealing performance evaluation, overcoming the shortcomings of low accuracy and high randomness in human experience-based judgment. It can obtain the support status of sheet piles under long-term operating conditions, preventing potential problems. Attached Figure Description

[0018] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0019] Figure 1 This application provides a flowchart of an in-situ testing process and monitoring method for the sealing performance of steel sheet pile joints; Figure 2 This is a schematic diagram showing the location of the pre-embedded pipe and the detection hole described in this application; Figure 3 This is a schematic diagram of the support structure formed by the sheet piles in this application; Figure 4 This is a schematic diagram of the structure of the pre-embedded pipe and the detection cylinder described in this application. Detailed Implementation

[0020] As described in the background section, common sheet pile cross-sectional shapes include U-shaped, Z-shaped, and straight-web type. Their delivery condition and length can be customized according to user requirements, with lengths reaching over twenty meters. Sheet pile installation methods include driving, vibration, static pressure, sedimentary hammer pile method, and vibratory pile driving method. However, for sheet piles, joint leakage is not completely eliminated by the cross-sectional shape or construction method. (See appendix) Figure 1 ~Appendix Figure 4 This application provides an in-situ testing process for the sealing performance of steel sheet pile joints, including the following steps: Step 1: Fix a pre-embedded pipe along the entire length of the soil-facing side of the steel sheet pile. The pre-embedded pipe has several openings distributed along its height.

[0021] The embedded pipe is a standard long pipe with several openings on its surface. The embedded pipe can be made of metal or non-metal, and its connection to the sheet pile can be welding, mechanical connection, or bonding.

[0022] Step 2: Install the combined structure of steel sheet piles and embedded pipes at the reserved positions of the steel sheet piles.

[0023] The installation method of the combined structure formed by steel sheet piles and pre-embedded pipes is the same as that of steel sheet piles, which can be one of the following: driving method, vibration method, static pressure method, sedimentation hammer pile method, and vibratory pile driving method.

[0024] Step 3: A test hole is opened vertically downward from the ground surface on the side of the foundation pit of the steel sheet pile. The depth of the test hole is equal to the length of the steel sheet pile.

[0025] In engineering, sheet piles are used for foundation pit support. The side of the sheet pile facing the foundation pit is called the foundation pit side, and the side facing the soil is called the soil-facing side. Inspection holes should be drilled vertically downwards, with the same length as the sheet pile. In practice, the embedded pipe is placed in the middle of the sheet pile, and the inspection hole should be drilled as close to the sheet pile as possible. The straight line connecting the inspection hole and the embedded pipe should be perpendicular to the sheet pile.

[0026] Step 4: Place a probe tube within the full depth of the detection hole. The probe tube has a filter-like tube wall and a core coated with a solid reagent, namely phenolphthalein powder.

[0027] The mesh-like cylinder wall protects solid reagents while allowing liquid reagents to penetrate. When the sheet pile is long, the test hole is also deeper. Long solid reagents placed in the test hole are prone to bending and deformation. Therefore, the cylinder wall also maintains the shape of the core, preventing inaccurate depth indications due to core deformation. Phenolphthalein powder can be bonded to the core to form a color-changing layer. The core can be made of wood or rubber, and its properties should be relatively stable and readily available.

[0028] Step 5: Based on the target detection depth, liquid reagent is injected into the pre-embedded pipe in stages from bottom to top using a grouting pump. The liquid reagent, upon contact with the solid reagent, causes the solid reagent to change color. The water pressure at the detection point depth exerts pressure on the liquid reagent, guiding it to penetrate into the foundation pit. Therefore, if leakage occurs, the color change of the solid reagent can be observed on the other side of the sheet pile.

[0029] Grouting pumps can be implemented using existing technology. The grouting pump has a dynamic pressure sensor that displays the grouting pressure in real time. The pressure to be applied is calculated based on the soil density and the required depth of detection. The grouting pump then monitors the pressure in real time to ensure that the expected depth is reached.

[0030] The target detection depth varies with each test. In practice, the target detection depth increases linearly over a certain span. For example, leakage is measured sequentially at distances of 3m, 6m, 9m, etc., from the bottom of the sheet pile, using a 3m span. The detection target is only the leakage channels affecting the safety of the foundation pit, i.e., defects in the support structure within the excavation area. Ultra-deep detection is technically infeasible, economically unreasonable, and has no practical safety value. The liquid reagent injected during testing needs to penetrate to the foundation pit side through joint defects, and its penetration path is controlled by the direction of the hydraulic gradient. If the detection point depth exceeds the foundation pit excavation depth, the reagent at the ultra-deep detection point may be affected by the reverse hydraulic gradient, making it difficult to effectively migrate to the foundation pit side. Moreover, the soil in the ultra-deep area has not undergone excavation disturbance, and its permeability coefficient may be significantly lower than that of the excavated area within the pit, hindering reagent diffusion and reducing sensitivity.

[0031] The reason for conducting tests in stages in the above steps is as follows: When the liquid reagent migrates towards the joint in the pre-embedded pipe driven by the grouting pressure, it is superimposed with the horizontal seepage force generated by the groundwater pressure. Under the dual pressure, the reagent mainly diffuses horizontally through the joint defects towards the detection holes on the pit side, and the vertical seepage component is significantly weakened. Staged testing further constrains the vertical migration range by releasing the pressure gradient layer by layer.

[0032] In practice, phenolphthalein powder can be used as the surface coating of the core, and alkaline liquids such as sodium hydroxide can be used as liquid reagents.

[0033] Step 6: Remove the core tube and mark the location of discoloration at the corresponding depth of the sheet pile as the leakage point. Seal the leakage point.

[0034] In a preferred embodiment of this application, the openings are evenly spaced along the height, with two openings at each height, each facing the joint. Since the sheet pile has two joints, providing openings facing both joints improves detection efficiency and accuracy. It should be noted that during sealing, it is not necessary to focus on which side of the joint is leaking, as the sealing material will cover the cross-section of the sheet pile through the openings.

[0035] In a preferred embodiment of this application, the solid reagent is phenolphthalein powder, and the liquid reagent is an alkaline reagent.

[0036] In a preferred embodiment of this application, the sealing method in step six is ​​as follows: A quick-setting water-blocking material is injected into the opening of the pre-embedded pipe at the leakage location and into the adjacent openings above and below it. When the spacing between the openings is small, for example, less than 30cm, this method can be used to inject the sealing material to compensate for possible seepage errors. Because the seepage of liquid reagent to the other side may result in vertical deviations, an additional opening on the upper side needs to be made for sealing to avoid errors.

[0037] In one specific embodiment of the above implementation, when there are two or more leakage locations, a quick-setting water-blocking material is injected into each opening in a bottom-to-top order. In specific implementation, the water-blocking material is quick-setting cement, which is prepared by adding a quick-setting agent to cement. The water-blocking material can be achieved using existing technology.

[0038] In a preferred embodiment of this application, the core has several segmented core units, and each core unit has an isolation gasket at its upper end. The communication unit, in conjunction with the isolation gasket, ensures the accuracy of the color change location while preventing liquid reagent from seeping down and affecting the test results. The isolation gasket can be made of rubber or plastic, and is used to separate the solid reagent into several segments before being snapped into the core wall. The detection cylinder adopts a segmented core unit design, with isolation gaskets between each unit. This structure effectively separates detection areas at different depths, ensuring that when liquid reagent penetrates at a specific depth, it only affects the core unit corresponding to the current segment. Even if there is a downward seepage tendency due to gravity, the physical barrier of the isolation gasket prevents the reagent from contaminating other segments, thus ensuring that the color change reaction only reflects the true leakage situation at the current detection depth. Moreover, with layered detection from bottom to top, if leakage occurs in the lower layer when detection is prioritized, a leak-sealing material is quickly injected. During subsequent upper layer detection, even if there is a downward seepage tendency, the sealed lower layer will form a water-blocking barrier, preventing the reagent from migrating downwards.

[0039] After the leak is plugged, the foundation pit is excavated. This application provides a method for monitoring the sealing performance of steel sheet pile joints based on the aforementioned in-situ testing process, including the following steps: S1. Measure the pore water pressure at the leakage location on the soil-facing side of the sheet pile where leakage has occurred. Horizontal displacement of pile body and pile side earth pressure ; S2. Measure the pore water pressure at the depth corresponding to the leakage location of the non-leaking sheet pile and the leaking sheet pile. Horizontal displacement of pile body and pile side earth pressure ; In practice, PVC piezometers with permeable sections are drilled and embedded to measure the water level inside the pipe, which is then converted into pore water pressure. Inclined pipes are pre-embedded within the pile body. A probe with guide wheels slides along the incline pipe, and an accelerometer measures the change in inclination angle to calculate the horizontal displacement of the pile body, supporting multi-depth point measurements. Earth pressure is measured using a vibrating wire earth pressure cell, which is welded or tied to the pile surface, and the earth pressure is measured by the change in the frequency of the steel wire.

[0040] S3, based on and Establish pore water pressure monitoring indicators : ; based on and Establish monitoring indicators for horizontal displacement of pile body : ; based on and Calculate the monitoring index of earth pressure on pile side : ; S4, based on , , Evaluation indices for the sealing performance of steel sheet piles were calculated using the weighted analysis method. The allowable value [K] for the evaluation index of the sealing performance of sheet piles is set. When K is less than [K], the sealing performance of sheet piles is judged to meet the requirements. When K is greater than or equal to [K], the sealing performance of sheet piles is judged to not meet the requirements.

[0041] Evaluation indicators of sealing performance of steel sheet piles The calculation formula is: ; In the formula, , , These are the influencing factors reflecting the degree of impact of pore water pressure at the leakage point, horizontal displacement of the pile body at the leakage point, and soil pressure on the pile side at the leakage point on the sealing performance of the steel sheet pile joint. All three factors must satisfy the following: .

[0042] In one specific embodiment, a linear weighting method is used to integrate multiple indicators into a single evaluation index. If the correlation coefficient between pore water pressure change and leakage accident is 0.6, horizontal displacement is 0.3, and earth pressure is 0.1, then the weights can be set as follows: , , If the sum of the final coefficients exceeds or falls short of 1, then force normalization can be performed after scaling.

[0043] In a preferred embodiment of this application, in S2, a non-leaking sheet pile is selected on each side of the sheet pile where leakage has occurred, and its distance from it is measured. , as well as The average value is then taken as the calculated value of the monitoring index. Leak-free sheet piles refer to sheet piles for which no leakage was detected within the safe control depth range of the foundation pit.

[0044] In S4, the method for determining the allowable value [K] of the steel sheet pile sealing performance evaluation index is as follows: According to the specifications, the allowable values ​​of horizontal displacement, soil pressure, and pore water pressure of the foundation pit support piles are determined, and [K] can be derived using the weighted analysis method. For example, if the specifications stipulate that the allowable horizontal displacement of the foundation pit support pile is 0.3% of the pile length, then the allowable horizontal displacement of the foundation pit support pile can be calculated based on the pile length. Other parameters are calculated similarly, and [K] can be derived after the calculation.

[0045] It should be noted that the length of the steel sheet piles in this application should preferably be controlled within 10m, which is sufficient to meet most construction requirements.

[0046] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0047] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A process for in-situ detection of the sealing performance of a steel sheet pile joint, characterized in that, It comprises the following steps: Step 1: Fix a pre-buried pipe along the whole length on the soil-facing side of the steel sheet pile, the pre-buried pipe has several openings distributed along the height; Step 2: Install the combined structure of steel sheet pile and pre-buried pipe at the reserved position of the steel sheet pile; Step 3: Open a detection hole vertically downward from the ground on the foundation pit side of the steel sheet pile, the depth of the detection hole is equal to the length of the steel sheet pile; Step 4: Place a detection cylinder in the full depth of the detection hole, the detection cylinder has a filter screen-shaped cylinder wall and a cylinder core coated with a solid reagent on the surface; Step 5: According to the target detection depth, fill the liquid reagent into the pre-buried pipe by the grouting pump from bottom to top in batches, the liquid reagent makes the solid reagent change color after contact with the solid reagent; Step 6: Take out the cylinder core, record the leakage position as the corresponding depth of the color change position on the steel sheet pile, and seal the leakage position.

2. The in-situ detection process for the sealing performance of the steel sheet pile joint according to claim 1, characterized in that: The openings are distributed at equal intervals along the height, and the number of openings at each height is two and they are respectively directed towards the joint.

3. The in-situ detection process for the sealing performance of the steel sheet pile joint according to claim 1, characterized in that: The solid reagent is phenolphthalein powder, and the liquid reagent is an alkaline reagent.

4. The in-situ detection process for the sealing performance of the steel sheet pile joint according to claim 1, characterized in that: The sealing method in step 6 is to inject quick-setting water plugging material into the openings of the pre-buried pipe at the leakage position and the adjacent openings above and below the openings.

5. The in-situ detection process for the sealing performance of the steel sheet pile joint according to claim 4, characterized in that: When the leakage position has two or more, the quick-setting water plugging material is injected into each opening in order from bottom to top.

6. The in-situ detection process for the sealing performance of the steel sheet pile joint according to claim 1, characterized in that: The cylinder core has several segmented cylinder core units, and the upper end of the cylinder core unit is provided with a spacer.

7. A method for monitoring the sealing performance of a steel sheet pile joint based on the in-situ detection process of claim 1, characterized by, It comprises the following steps: S1, measuring the pore water pressure at the leakage position of the soil-facing side of the steel sheet pile where leakage occurs , pile body horizontal displacement , and pile side soil pressure ; S2, measure the pore water pressure at the depth corresponding to the leakage position of the leaked steel sheet pile in the non-leaked steel sheet pile , pile body horizontal displacement , and pile side soil pressure ; S3, based on and Establishing a pore water pressure monitoring index : ； Based on and Establishing pile body horizontal displacement monitoring index : ； Based on and Computing pile side soil pressure monitoring index : ； S4, based on , , Steel sheet pile sealing performance evaluation index is calculated by weight analysis method , and the steel sheet pile sealing performance evaluation index allowable value [K] is set. When K is less than [K], it is determined that the steel sheet pile sealing performance meets the requirements, and when K is greater than or equal to [K], it is determined that the steel sheet pile sealing performance does not meet the requirements.

8. The steel sheet pile joint sealing performance monitoring method of the in-situ detection process according to claim 7, characterized in that: In S2, one of the non-leaking steel sheet piles closest to the leaking steel sheet pile on each side of the leaking steel sheet pile is selected to measure the , and average value of the measured values as the calculated value of the monitoring index.

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