A simulation test detection method for the whole process of steel sheet pile insertion and extraction

Abstract

The present application belongs to the field of underground engineering, and particularly relates to a simulation test detection method for the whole process of steel sheet pile insertion and extraction. The simulation device is manufactured, and a soil layer of a certain depth unit is laid in a model box of the simulation device. The insertion of the steel sheet pile at an arbitrary stratum depth can be effectively simulated through the heaped load. Quantitative indexes before and after the insertion of the steel sheet pile are established, the disturbance of the insertion to the soil body is effectively represented, the recovery rate indexes of the disturbed area and the undisturbed area and the comprehensive treatment evaluation indexes are established, the comprehensive evaluation of the treatment effect is realized, the objective evaluation system based on the core quantitative indexes of the soil body density change, the surface settlement amount (displacement), the strength and the like is established, and the limitations brought by the traditional simple dependence on the qualitative analysis are overcome.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering, and specifically relates to a simulation test method for the entire process of inserting and extracting steel sheet piles. Background Technology

[0002] Steel sheet piles are driven into the ground to withstand and resist earth and water pressure, thus forming temporary or permanent retaining and water-retaining barriers. Due to its superior performance, steel sheet pile technology is widely used in geotechnical engineering and underground structures, hydraulic and marine engineering, transportation infrastructure engineering, and environmental engineering. The driving and extraction processes of steel sheet piles can disturb the surrounding strata, potentially leading to soil deformation, surface settlement, and other problems that could affect the safety of surrounding structures. Therefore, simulating the steel sheet pile construction process through model tests and analyzing the range of ground disturbance and its treatment effects is of great significance for guiding practical engineering projects.

[0003] There are some devices and testing methods on the market for simulating and analyzing the support effect of sheet piles, or for studying the performance of sheet pile support structures. However, there are almost no simulation devices for studying the disturbance of the surrounding strata caused by the insertion and extraction of sheet piles. Furthermore, due to the long length and deep penetration of sheet piles in actual engineering projects, it is difficult to use simulation devices to study the disturbance of the soil by sheet piles in deeper strata. The model size requirements are too high, resulting in complex test system construction and high implementation costs, which seriously restricts the feasibility and practicality of related test methods.

[0004] Furthermore, the current parameter system for monitoring formation disturbance processes is too simplistic, failing to systematically and comprehensively cover key indicators characterizing soil mechanical response, such as soil density and strength, leading to significant limitations in understanding the disturbance mechanism. Post-experiment evaluation of formation treatment effects primarily relies on qualitative analysis, lacking a quantitative comparison system based on soil density variation characteristics, making it difficult to accurately quantify and evaluate the actual effectiveness of different treatment processes. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a simulation test method for the entire process of inserting and extracting steel sheet piles.

[0006] This invention proposes a simulation test method for the entire process of inserting and extracting steel sheet piles, comprising the following steps:

[0007] S1: Construct a simulation device, which includes a reaction frame fixed on the ground. A hydraulic cylinder is installed downward in the middle of the reaction frame. The lower end of the hydraulic rod of the hydraulic cylinder is fixed to the upper end of the test sheet pile. A model box is set below the hydraulic cylinder. Collect soil samples from the depth unit downward at depth H on site. Lay the collected soil samples into the model box. Except for the soil layer directly below the test sheet pile, place several weights evenly on the upper surface of the remaining soil layers in the model box. The weights are used to represent the load above the equivalent depth unit soil.

[0008] S2: Take m circumferential survey lines at a certain depth in the disturbed area of ​​the soil layer in the model box, and take n measuring points on each circumferential survey line to measure the displacement, strength, and compaction of each measuring point; the area whose horizontal distance from the longitudinal center axis of the test steel sheet pile is not greater than the thickness of the soil layer in the model box is considered as the disturbed area, and the area whose horizontal distance from the longitudinal center axis of the test steel sheet pile is greater than the thickness of the soil layer in the model box is considered as the undisturbed area.

[0009] S3: The hydraulic cylinder slowly inserts the test sheet pile into the soil layer inside the model box, and then the hydraulic cylinder pulls the test sheet pile out of the soil layer inside the model box.

[0010] S4: After the test sheet pile is pulled out, measure the displacement, strength, and density of each measuring point taken in step S2 again.

[0011] S5: The first [unit / item] on a certain circumferential survey line The difference rate index for each measurement point was established.

[0012] S6: Establishment of the average difference rate index for a certain circumferential survey line.

[0013] S7: Establishment of a volatility index for a certain circumferential measurement line.

[0014] S8: Establishment of disturbance evaluation index for a certain circumferential survey line.

[0015] S9: Calculate the weighting coefficients of the comprehensive disturbance evaluation index.

[0016] S10: Constructing a comprehensive disturbance evaluation index Set the allowed value N i When the comprehensive disturbance evaluation index Greater than the allowable value N i When this happens, the holes need to be treated; when the comprehensive disturbance evaluation index Not greater than the allowable value N i In this case, no treatment of the holes is required.

[0017] S11: Select a location within the hole treatment area of ​​the model box, or select an undisturbed area within the model box. The location, for the area where the hole was treated and the undisturbed area. The soil density, penetration resistance, and unconfined compressive strength were measured at each location.

[0018] S12: Establish recovery rate indicators.

[0019] S13: Calculate the weighting coefficient of the comprehensive quantitative evaluation index K.

[0020] S14: Construct a comprehensive quantitative evaluation index K.

[0021] S15: Establish quality evaluation standards for hole treatment; if If the value is less than 0.3, it indicates poor hole treatment quality, requiring secondary treatment; if 0.3 ≤ If the value is less than 0.7, it indicates that the hole treatment quality is unqualified and secondary treatment is required; if 0.7 ≤ If ≤1.2, it indicates that the hole treatment is qualified; if A score >1.2 indicates excellent hole treatment.

[0022] Furthermore, in step S5, the first [item] on a certain circumferential measuring line The difference rate index for each measurement point is established as follows:

[0023] The first on a certain circumferential survey line The displacement difference rate index at each measuring point is: The calculation formula is as follows:

[0024] ;

[0025] in, This indicates the first test sheet pile on a certain circumferential survey line before driving. Displacement test values ​​corresponding to each measuring point; This indicates the first [number] test sheet pile on a certain circumferential measuring line after the test sheet pile has been pulled out. Displacement test values ​​corresponding to each measuring point;

[0026] The first on a certain circumferential survey line The intensity difference rate index at each measuring point is: The calculation formula is as follows:

[0027] ;

[0028] in, This indicates the first test sheet pile on a certain circumferential survey line before driving. The strength test values ​​corresponding to each measuring point; This indicates the first [number] test sheet pile on a certain circumferential measuring line after the test sheet pile has been pulled out. The strength test values ​​corresponding to each measuring point;

[0029] The first on a certain circumferential survey line The density difference rate index at each measuring point is: Its calculation formula is

[0030] ;

[0031] in, This indicates the first test sheet pile on a certain circumferential survey line before driving. The density test value corresponding to each measuring point; This indicates the first [number] test sheet pile on a certain circumferential measuring line after the test sheet pile has been pulled out. The density test value corresponding to each measuring point.

[0032] Furthermore, in step S6, the average difference rate index of a certain circumferential measurement line is established as follows:

[0033] The average displacement difference rate index for a certain circumferential survey line is calculated using the following formula:

[0034] ;

[0035] The average strength difference rate index for a certain circumferential survey line is calculated using the following formula:

[0036] ;

[0037] The average density difference rate index for a certain circumferential survey line is calculated using the following formula:

[0038] .

[0039] Furthermore, in step S8, the disturbance evaluation index for a certain circumferential survey line is established as follows:

[0040] To evaluate the displacement disturbance impact of sheet pile driving on the surrounding soil, the calculation formula is as follows:

[0041] ;

[0042] To evaluate the strength disturbance index of the impact of sheet pile driving on the surrounding soil, the calculation formula is as follows:

[0043] ;

[0044] To evaluate the compaction disturbance index of the impact of sheet pile driving on the surrounding soil, the calculation formula is as follows:

[0045] .

[0046] Furthermore, in step S9, the calculation of the weighting coefficients of the comprehensive disturbance evaluation index includes the following steps:

[0047] S91: Calculate the average disturbance evaluation index for each of the m circumferential survey lines; the average disturbance evaluation index for each of the m circumferential survey lines is as follows: The calculation formulas are as follows:

[0048] ;

[0049] ;

[0050] ;

[0051] in, Represents the first of m circumferential survey lines. One circumferential survey line;

[0052] S92: Calculate the jump value of the disturbance evaluation index; the jump value of the disturbance evaluation index includes the jump value of the displacement disturbance evaluation index. Intensity disturbance evaluation index jump value The jump value of the density disturbance evaluation index The calculation formulas are as follows:

[0053] ;

[0054] ;

[0055] ;

[0056] S93: Calculate the coefficient of variation The calculation formulas are as follows:

[0057] ;

[0058] ;

[0059] ;

[0060] S94: Calculate the weighting coefficients of the comprehensive disturbance evaluation index, and the calculation formulas are as follows:

[0061] ;

[0062] ;

[0063] .

[0064] Furthermore, in step S10, the comprehensive disturbance evaluation index The structure is as follows:

[0065] ;

[0066] in, ; , , This is the disturbance evaluation index corresponding to any circumferential survey line.

[0067] Furthermore, in step S12, the recovery rate index is established as follows:

[0068] The density recovery rate is an index, and its calculation formula is as follows:

[0069] ;

[0070] The penetration resistance recovery rate index is calculated using the following formula:

[0071] ;

[0072] The unconfined compressive strength recovery rate is an index, and its calculation formula is as follows:

[0073] ;

[0074] Where, ρ 处 , qc 处 U 处 These represent the density, penetration resistance, and unconfined compressive strength of the selected location for the cavity treatment, respectively; ρ 未 , qc 未 U 未 These represent the density, penetration resistance, and unconfined compressive strength at a specific location in the undisturbed zone, respectively.

[0075] Furthermore, in step S13, calculating the weighting coefficient of the comprehensive quantitative evaluation index K includes the following steps:

[0076] S131: Calculate the average value of the recovery rate index; calculate separately. The recovery rate index at each location, then the average density recovery rate index Average value of penetration resistance recovery rate index Average value of unconfined compressive strength recovery rate The calculation formulas are as follows:

[0077] ;

[0078] ;

[0079] ;

[0080] in, express The first position in the position One location, ;

[0081] S132: Calculate the jump value of the recovery rate index; jump value of the density recovery rate index. Penetration resistance recovery rate index jump value Unconfined compressive strength recovery rate index jump value The calculation formulas are as follows:

[0082] ;

[0083] ;

[0084] ;

[0085] S133: Calculate the coefficient of variation; coefficient of variation The calculation formulas are as follows:

[0086] ;

[0087] ;

[0088] ;

[0089] S134: Weighting coefficients of comprehensive quantitative evaluation indicators The calculation formulas are as follows:

[0090] ;

[0091] ;

[0092] .

[0093] Furthermore, in step S14, the comprehensive quantitative evaluation index K is constructed as follows:

[0094] ;

[0095] in ; , , for The data value corresponding to any position in the given positions.

[0096] Beneficial effects of this invention:

[0097] 1. This invention can effectively simulate the driving of sheet piles at any stratum depth by surcharge, and can analyze the disturbance state of the soil around the sheet piles at any stratum depth through simulation tests. It overcomes the problem of the excessive size of existing models and provides a feasible solution for the disturbance analysis of deep soil layers caused by sheet pile driving.

[0098] 2. Quantitative indicators were established before and after the steel sheet pile driving to effectively characterize the disturbance of the soil caused by driving. Recovery rate indicators for disturbed and undisturbed areas and comprehensive treatment evaluation indicators were also established to achieve a comprehensive evaluation of the treatment effect.

[0099] 3. By increasing the monitoring of multiple parameters such as soil compaction and strength, the disturbance and impact of sheet pile construction on the surrounding strata can be revealed more comprehensively and systematically.

[0100] 4. An objective evaluation system based on core quantitative indicators such as soil density change, surface settlement (displacement), and strength was established, overcoming the limitations of traditional reliance on qualitative analysis.

[0101] 5. When the soil layer under study is deep, the present invention can also be effectively simulated by scaling down, which can realize the study of steel sheet pile insertion and extraction tests in deeper strata. Attached Figure Description

[0102] Figure 1 This is a schematic diagram of the depth unit structure in this embodiment;

[0103] Figure 2 A schematic diagram of the longitudinal central axis structure of the test steel sheet pile;

[0104] Figure 3 This is a schematic diagram of the simulation device structure in this embodiment;

[0105] Figure 4 This is a schematic diagram of the circumferential survey line structure;

[0106] Figure 5 This is a schematic diagram of the comprehensive disturbance evaluation process in this embodiment;

[0107] Figure 6 This is a schematic diagram of the hole treatment quality evaluation process in this embodiment.

[0108] In the figure, 1 is the reaction frame, 2 is the hydraulic cylinder, 3 is the test sheet pile, 4 is the model box, 5 is the load, 6 is the soil layer, 7 is the circumferential survey line, 8 is the center of the test sheet pile, and 9 is the longitudinal center axis of the test sheet pile. Detailed Implementation

[0109] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0110] The simulation device for the entire process of inserting and extracting sheet piles includes a pressure device and a test chamber. The pressure device includes a reaction frame 1 and a hydraulic cylinder 2, which can simulate the insertion and extraction of the test sheet piles 3. The test chamber includes the test sheet piles 3, a model box 4, a load surcharge 5, and a soil layer 6, which can simulate the on-site soil conditions.

[0111] The reaction frame 1 is fixed to the ground in an inverted U-shape. A hydraulic cylinder 2 is fixedly mounted on the inner surface of the reaction frame 1, facing downwards. The lower end of the hydraulic rod of the hydraulic cylinder 2 is fixed to the upper end of the test sheet pile 3. The hydraulic cylinder 2 is directly connected to a high-precision electro-hydraulic servo control system via a high-pressure oil pipe, and its movement is driven and controlled in a closed loop by a dedicated servo amplifier. The model box 4 has a cubic structure with an open top and is preferably made of transparent acrylic sheet, which facilitates observation of the test process. To increase the strength of the model box 4, steel pipes can be added to the edges of the model box 4 for support.

[0112] Soil layer 6 is laid inside model box 4. Soil layer 6 consists of soil samples collected on-site, and the layer is laid according to the actual stratification on-site. A soil layer of any depth unit is selected, and the soil sampled on-site for that depth unit is laid according to its actual condition. For example, if the depth unit is 1m, and the disturbance of the soil layer at depth 5-6m is to be studied, soil samples are collected on-site at a depth of 5-6m, and the collected soil samples are laid inside model box 4 according to the actual stratification of the soil layer at that depth unit to recreate the real soil layer condition at that depth unit. A load 5 is evenly placed on top of soil layer 6 inside model box 4. The load 5 is preferably a large weight, but other heavy objects can also be used. The load 5 is used to simulate the actual load above the soil body at the selected depth unit. Its total weight is set according to the load requirements determined by theoretical analysis or numerical simulation to accurately simulate the action of the load 5 under actual working conditions. For example, if the selected depth unit is the soil layer downwards at depth H, as shown in the attached figure... Figure 1 As shown, the load on the soil above depth H is:

[0113] ;

[0114] in, , The thickness of each stratum above depth H; The unit weight of the soil strata above depth H. The actual load on the soil above the selected depth unit can be calculated from the survey report. This actual load is the load that needs to be applied above soil layer 6 within model box 4. An equivalent load is applied above soil layer 6 within model box 4 by placing weights. The total weight of the weights required is: × Model box area, to simulate the initial stress environment of the target stratum.

[0115] The test sheet pile 3 is used to simulate the driving process to study its impact on the soil. The length of the test sheet pile 3 is not less than the height of the selected depth unit, i.e., the length of the test sheet pile 3 is not less than the thickness of the soil layer 6 laid in the model box 4. The test sheet pile 3 can be an actual sheet pile used in construction, but its length is much shorter than that of the actual sheet pile. Preferably, the length of the test sheet pile 3 is 2-10 cm longer than the thickness of the soil layer 6 laid in the model box 4. A section can be cut from an actual sheet pile used in construction as the test sheet pile 3.

[0116] The length of the test sheet pile 3 is determined based on the height of the depth unit. Then, the dimensions of the model box 4 are determined based on the dimensions of the test sheet pile 3. The width of the model box 4 is not less than twice the width of the test sheet pile 3, and the length of the model box 4 is not less than three times the length of the test sheet pile 3.

[0117] When studying deeper soil layers, to further reduce the size of the simulation test device and lower costs, the thickness of each soil layer 6, the load 5 above it, and the width of the test sheet pile 3 in the depth unit can all be scaled down proportionally. For example, with a scaling ratio of 1:10, if the soil below a depth of 10m needs to be studied, and the depth unit is 2m, meaning the soil layer at a depth of 10-12m needs to be studied, then by scaling down the thickness of each soil layer in the depth unit by 1:10, the thickness of the soil layer 6 laid in the model box 4 according to the scaling ratio will be 0.2m. Similarly, the load 5 is also scaled down proportionally according to the actual calculated load. If, under actual working conditions, the actual load P above the soil in the depth unit according to the survey report is 200kPa, then a load of 20kPa needs to be added above the soil layer 6 in the model box 4. The total weight of the weights to be placed is: 20kPa × the area of ​​the model box. The width of the test sheet pile 3 also needs to be scaled down according to the scaling ratio. For example, if the actual width of the sheet pile used in construction is 500mm, then the width of the test sheet pile 3 should be 50mm.

[0118] Using the above-mentioned sheet pile simulation device, the simulation test method of the present invention for the entire process of sheet pile insertion and extraction includes the following steps:

[0119] Step 1: Constructing the simulation device

[0120] Determine the depth of the strata under study and the depth unit to be sampled, and construct a simulation device. Collect soil samples from the depth unit in the field, and fill the collected soil samples into the model box 4 according to the actual stratification, controlling its compaction and uniformity to ensure consistency with the field soil layers. Calculate the required surcharge 5 based on the actual load above the field depth unit, and apply the surcharge 5 above the soil layer 6 inside the model box 4 according to the calculated data. Do not apply the surcharge 5 above the soil layer 6 directly below the test sheet pile 3.

[0121] If the soil depth of the depth unit being studied is relatively deep, a suitable scale ratio can be determined first. The thickness of the soil layer 6 laid in the model box 4, the width of the test sheet pile 3, and the weight of the surcharge 5 are all made according to the scale ratio. The length of the test sheet pile 3 is slightly larger than the thickness of the soil layer 6 laid. The size of the model box 4 is made according to the size of the test sheet pile 3.

[0122] Step 2: Within the disturbed area at a certain depth in soil layer 6 of model box 4, take m circumferential survey lines 7, and on each circumferential survey line 7, take n measuring points to measure the displacement, strength, and density of each measuring point.

[0123] In the disturbed area of ​​soil layer 6 within model box 4, m circumferential survey lines 7 are taken respectively. The disturbed area refers to the area where the soil is disturbed by the insertion of the test sheet pile 3. In this embodiment, the area whose horizontal distance from the longitudinal central axis 9 of the test sheet pile is not greater than the total thickness of soil layer 6 in model box 4 is considered the disturbed area, and the area whose horizontal distance from the longitudinal central axis 9 of the test sheet pile is greater than the total thickness of soil layer 6 in model box 4 is considered the undisturbed area. The longitudinal central axis is the line where the center point 8 of the test sheet pile is located, as shown in the attached figure. Figure 2 As shown in the attached diagram. The circumferential survey line 7 refers to the curve formed by circling the test sheet pile at a certain depth with the center 8 as the center and a certain length as the radius, as shown in the attached diagram. Figure 4 As shown, m circular curves with radii of different lengths are formed by making one loop, which constitutes m circumferential measuring lines 7. n measuring points are taken on each circumferential measuring line 7, resulting in a total of n measuring points. There are 10 measuring points, all within the disturbed area, and all measuring points have the same depth. The center of the test sheet pile 3 at a certain depth is located on the longitudinal central axis 9 of the test sheet pile. A certain depth can be arbitrarily selected within the soil layer 6 inside the model box 4.

[0124] Before the test sheet pile 3 was driven, the displacement, strength, and density of each measuring point were measured. Then, the first [point] on a certain circumferential measuring line 7 was [measured]. The displacement test value corresponding to each measuring point is Strength test value The density test value is .

[0125] Displacement is measured using the commonly used leveling method; common strength measurement methods include direct shear test, triaxial compression test, unconfined compressive strength test, and vane shear test, and any one of these methods can be used for strength measurement; common density measurement methods include nuclear density meter method, sand filling method, water filling method, and shaking table method, and the test method can be selected according to the actual situation, without any restrictions.

[0126] Step 3: Test steel sheet pile insertion and extraction operation

[0127] Operate the hydraulic cylinder 2 to slowly insert the test sheet pile 3 into the soil layer 6 inside the model box 4 from the opening at the top of the model box 4. Then, use the hydraulic cylinder 2 to pull the test sheet pile 3 out of the soil layer 6 inside the model box 4.

[0128] Step 4: Measure the displacement, strength, and density of each measuring point again.

[0129] After the test sheet pile 3 is pulled out, immediately remeasure the displacement, strength, and density of the measuring points taken in step two. The testing method is the same as in step two. At this time, the first [unit / item] on a certain circumferential measuring line 7 will be [measured / measured]. The displacement test value corresponding to each measuring point is Strength test value The density test value is .

[0130] Step 5: The first [item] on a certain circumferential survey line 7 Establishment of the difference rate index for each measuring point

[0131] The 7th circumferential survey line The displacement difference rate index for each measuring point was established: based on the displacement values ​​of the soil before and after the test sheet pile 3 was driven and pulled out, the displacement difference rate index was established. This index was established on the first measuring point along a certain circumferential measuring line 7. The displacement difference rate index at each measuring point is: The calculation formula is as follows:

[0132] ;

[0133] The 7th circumferential survey line Establishment of the strength difference rate index for each measuring point: Based on the strength values ​​of the soil before and after the test sheet pile 3 was driven and pulled out, a strength difference rate index was established. This index was established on the 7th measuring point along a certain circumferential measuring line. The intensity difference rate index at each measuring point is: The calculation formula is as follows:

[0134] ;

[0135] The 7th circumferential survey line Establishment of the density difference rate index for each measuring point: Based on the density values ​​of the soil before and after the test sheet pile 3 is driven, a density difference rate index is established. This index is based on the density values ​​of the soil at a certain circumferential measuring line 7. The density difference rate index at each measuring point is: Its calculation formula is

[0136] .

[0137] Step Six: Establishing the average difference rate index for a certain circumferential survey line 7

[0138] Based on the difference rate index, establish the average difference rate index E.

[0139] The average displacement difference rate index is given by [reference to index 7], and the displacement difference rate is given by [reference to index 7] for n measuring points on this circumferential measuring line 7. ( The average displacement difference rate index is calculated using the average value of (1, 2, 3…n).

[0140] ;

[0141] The average strength difference rate index is given by n measuring points on a certain circumferential measuring line 7. ( The average strength difference rate index is calculated using the average value of (1, 2, 3…n).

[0142] ;

[0143] The average density difference rate index is given by n measuring points on a certain circumferential measuring line 7. ( The average density difference rate index is calculated using the average value of (1, 2, 3…n).

[0144] ;

[0145] Step 7: Establishing a volatility index for a certain circumferential test line 7

[0146] Based on the difference rate index and the average difference rate index, a volatility index C is established.

[0147] The displacement fluctuation rate index of a certain circumferential measuring line 7 is calculated from the displacement difference rate index and the average displacement difference rate index of n measuring points on this circumferential measuring line 7. The calculation formula is as follows:

[0148] ;

[0149] The intensity fluctuation rate index of a certain circumferential measuring line 7 is calculated from the intensity difference rate index and the average intensity difference rate index of n measuring points on this circumferential measuring line 7. The calculation formula is as follows:

[0150] ;

[0151] The density fluctuation rate index of a certain circumferential measuring line 7 is calculated from the density difference rate index and the average density difference rate index of n measuring points on this circumferential measuring line 7. The calculation formula is as follows:

[0152] .

[0153] Step 8: Establishment of disturbance evaluation index for a certain circumferential survey line 7

[0154] Based on the average difference rate index and the volatility index, a disturbance evaluation index ξ is constructed to assess the impact of the test steel sheet pile driving on the surrounding soil.

[0155] To evaluate the displacement disturbance impact of the third-stage steel sheet pile driving on the surrounding soil, the calculation formula is as follows:

[0156] ;

[0157] To evaluate the strength disturbance index of the impact of three-stage steel sheet pile driving on the surrounding soil, the calculation formula is as follows:

[0158] ;

[0159] To evaluate the impact of three-stage sheet pile driving on the surrounding soil, the density disturbance index is calculated using the following formula:

[0160] .

[0161] Step 9: Calculate the weighting coefficients of the comprehensive disturbance evaluation index.

[0162] Based on the methods in steps five through eight, the disturbance evaluation indices for each of the m circumferential survey lines 7 are calculated. Therefore, the displacement disturbance evaluation indices for the m circumferential survey lines 7 are as follows: The intensity disturbance evaluation indices for m circumferential survey lines 7 are as follows: The density disturbance evaluation indices for m circumferential survey lines 7 are as follows: .

[0163] The weighting coefficients of the comprehensive disturbance evaluation index are as follows: Based on the test values ​​of m circumferential survey lines 7, The specific calculation method is as follows:

[0164] (1) Calculate the average value of the disturbance evaluation index for each of the m circumferential survey lines 7.

[0165] The average values ​​of the disturbance evaluation indices for m circumferential survey lines 7 are as follows: The calculation formulas are as follows:

[0166] ;

[0167] ;

[0168] ;

[0169] in Indicates the 7th circumferential survey line out of m circumferential survey lines. 7 circumferential survey lines.

[0170] (2) Calculate the jump value of the disturbance evaluation index

[0171] The jump values ​​of the disturbance evaluation index include the jump values ​​of the displacement disturbance evaluation index. Intensity disturbance evaluation index jump value The jump value of the density disturbance evaluation index The calculation formulas are as follows:

[0172] ;

[0173] ;

[0174] .

[0175] (3) Calculate the coefficient of variation The calculation formulas are as follows:

[0176] ;

[0177] ;

[0178] .

[0179] (4) Calculate the weighting coefficients of the comprehensive disturbance evaluation index. The calculation formulas are as follows:

[0180] ;

[0181] ;

[0182] .

[0183] Step 10: Construct a comprehensive disturbance evaluation index and set allowable values ​​for judgment.

[0184] Establish a comprehensive disturbance evaluation index for the impact of sheet pile driving on the surrounding soil. To determine the correlation coefficient reflecting the impact of sheet pile driving on soil deformation, soil strength, and soil density disturbance, this study aims to assess the scope and magnitude of the disturbance caused by sheet pile driving on the soil, and to comprehensively evaluate the disturbance index. The structure is as follows:

[0185] ;

[0186] in ; , , The disturbance evaluation index is the one corresponding to any circumferential survey line 7.

[0187] Set the allowable value N for the comprehensive disturbance evaluation index i Allowed value N i The following process can be followed: First, determine the safety level of the foundation pit. The determination of the safety level of the foundation pit can be based on the "Technical Specification for Foundation Pit Support" (JGJ 120), and extract the corresponding deformation control standard as the basic threshold. Then, obtain actual disturbance data through numerical simulation analysis to calibrate the theoretical value. Based on reliability theory, comprehensively consider the variability of soil layer 6 and the importance of the project, and finally give N. i Value. The above determines the allowable value N. i The process is a systematic engineering project that integrates standards, numerical simulation, and experimental verification. When considering comprehensive disturbance evaluation indicators... Exceeding the allowed value N i When this happens, the hole formed after the test sheet pile 3 is pulled out needs to be treated; when the comprehensive disturbance evaluation index Not greater than the allowable value N i In this case, there is no need to treat the hole formed after the test sheet pile 3 is pulled out.

[0188] When cavities need to be treated, sand filling or grouting methods can be used to fill them to prevent the surrounding soil from collapsing or groundwater from seeping in. Sand filling utilizes the fluidity and compactability of medium-coarse sand, using vibration or water injection to compact the sand and fill the cavities, forming a stable structure. The material selection for sand filling should be: clean medium-coarse sand with a particle size of 0.25–0.50 mm and a mud content ≤3%; a bulk density of 1.36–1.60 g / cm³; and a porosity of 42%–47%. Grouting involves filling pores, cracks, or structural voids in the soil and rock with grout under pressure. After solidification, it forms a "stone body," improving the integrity, strength, and impermeability of the formation. The material performance requirements for grouting are: good fluidity, permeability, bonding strength, and durability.

[0189] Step 11: Select a location within the undisturbed area of ​​the hole treatment area. The location, for the area where the hole was treated and the undisturbed area. Soil density, penetration resistance, and unconfined compressive strength were measured at all locations.

[0190] In step ten, when the comprehensive disturbance evaluation index Exceeding the allowed value N i When the test sheet pile 3 is pulled out, it is necessary to treat the location where a hole is formed in the soil layer 6. The treated hole is called the treated hole area. A location can be randomly selected within the treated hole area, and simultaneously, an undisturbed area at the same depth as the selected location should be selected. One location, All locations are on the same circumferential measuring line 7. Circumferential measuring line 7 is any circumferential measuring line 7 within the undisturbed area, and its definition is the same as in step two. This applies to the locations selected at the hole treatment site and those selected within the undisturbed area. The density, penetration resistance, and unconfined compressive strength at each location were measured.

[0191] The density, penetration resistance, and unconfined compressive strength of the selected location for the cavity treatment are as follows: ρ 处 , qc 处 U 处 The density, penetration resistance, and unconfined compressive strength at a certain location in the undisturbed region are respectively: ρ 未 , qc 未 U 未 .

[0192] Step 12: Establish recovery rate indicators

[0193] Based on the data measured in step eleven, establish the recovery rate index k.

[0194] The density recovery rate is an index, and its calculation formula is as follows:

[0195] ;

[0196] The penetration resistance recovery rate index is calculated using the following formula:

[0197] ;

[0198] The unconfined compressive strength recovery rate is an index, and its calculation formula is as follows:

[0199] .

[0200] Step 13: Calculate the weighting coefficient of the comprehensive quantitative evaluation index K.

[0201] The weighting coefficient of the comprehensive quantitative evaluation index K is: Based on the test values ​​from step eleven, The specific calculation method is as follows:

[0202] (1) Calculate the average value of the recovery rate index

[0203] Calculate according to step twelve. The recovery rate index at each location was obtained. The density recovery rate indices for each location are as follows: The penetration resistance recovery rate indices at each location are as follows: The unconfined compressive strength recovery rate indices at each location are as follows: The above measurements were taken from the areas where holes were treated, and compared with... It is obtained by dividing the measurement data at each location.

[0204] The average density recovery rate index Average value of penetration resistance recovery rate index Average value of unconfined compressive strength recovery rate The calculation formulas are as follows:

[0205] ;

[0206] ;

[0207] ;

[0208] in, express The first position in the position One location, .

[0209] (2) Calculate the jump value of the recovery rate index

[0210] Density recovery rate index jump value Penetration resistance recovery rate index jump value Unconfined compressive strength recovery rate index jump value The calculation formulas are as follows:

[0211] ;

[0212] ;

[0213] .

[0214] (3) Calculate the coefficient of variation

[0215] coefficient of variation The calculation formulas are as follows:

[0216] ;

[0217] ;

[0218] .

[0219] (4) Calculate the weighting coefficients

[0220] Weighting coefficients of comprehensive quantitative evaluation indicators The calculation formulas are as follows:

[0221] ;

[0222] ;

[0223] .

[0224] Step Fourteen: Construct a comprehensive quantitative evaluation index K

[0225] A comprehensive quantitative evaluation index for the treatment effect of experimental steel sheet piles in strata voids was established based on the recovery rate index and the weighting coefficients of the comprehensive quantitative evaluation index. , The comprehensive impact of the treatment on formation density, penetration resistance, and unconfined compressive strength in the treated area after the reaction cavity treatment is calculated using the following formula:

[0226] ;

[0227] in ; , , for The data value corresponding to any position in the given positions.

[0228] Step 15: Establish quality evaluation standards for hole treatment

[0229] The establishment of a quality evaluation standard for void treatment can be based on engineering functional objectives and design specifications. This involves statistical analysis of numerous models and field test data from different soil types and processes to determine the correlation between various recovery rate indicators and the probability of engineering failure, thereby defining preliminary data boundaries for "unqualified," "qualified," and "excellent." These preliminary data boundaries are then used in simulation tests to verify their effectiveness. The quality evaluation standard for void treatment established in this embodiment is as follows:

[0230] like If the value is less than 0.3, it indicates poor processing quality and the overall processing fails to meet the standards, requiring secondary processing; if 0.3 ≤ If the value is less than 0.7, it indicates that the hole treatment quality is unqualified, with small areas being loose or void, requiring secondary treatment.

[0231] If 0.7≤ If the value is ≤1.2, it indicates that the hole treatment is qualified;

[0232] like A score >1.2 indicates excellent hole treatment.

[0233] The above-mentioned method for secondary treatment when hole treatment is unsatisfactory is as follows:

[0234] when In cases where the density is <0.3, the secondary treatment method is as follows: remove the original filler material, drill or excavate to remove the unqualified filler material, check the stability of the soil in the borehole wall, and provide temporary support if necessary; then carry out optimized process refilling, using grouting method for refilling, and using stable grout or mixed grout for grouting to improve impermeability, and control the pressure during grouting; or sand filling method can be used for refilling, strictly following the specifications, the sand must be screened, washed and dried, sand is filled in layers, water is injected and vibrated, pause and vibrate every 1m of elevation, and finally the borehole opening is sealed with 1:1 cement mortar to prevent seepage.

[0235] When 0.3≤ In cases where the density is less than 0.7, the secondary treatment methods are as follows: If there is localized insufficiency and a risk of water seepage, grouting can be used. Drill holes to the defective area and inject cement grout or cement-water glass double-liquid grout through pre-set grouting pipes or new holes. The grouting should be carried out in sections, with low pressure and intermittent injection of thick grout. Intermittent grouting should be controlled to 15 minutes each time to avoid the grout spreading too far. If the overall soil is loose or the original process was sand filling, sand can be used to fill the soil. The original loose filler should be cleaned up and re-layered, with each layer less than 1m, filled with medium and coarse sand. Each layer should be watered and vibrated to compact it, or cement mortar can be injected to enhance the bonding.

[0236] The following example illustrates the process using a real steel sheet pile construction project:

[0237] The soil depth H studied was 1m, and the depth unit was 0.5m. A model box 4 was constructed, with internal dimensions of 200cm × 100cm × 100cm (length × width × height). At the construction site, the soil layer 6 at depth unit 0.5m below the 1m depth consisted of two layers of silt, each 0.25m thick. Soil samples were collected on-site and laid into model box 4. The soil layer 6 inside model box 4 was 0.5m thick, consisting of two 0.25m layers of silt. The compaction and uniformity of the laid soil layers were consistent with the actual soil layers on site. The actual sheet piles used in the project were 10m long and 500mm wide, while the experimental sheet pile 3 was 0.6m long and 0.5m wide. According to the survey report, the upper load of the depth unit under actual working conditions... The equivalent load applied to the upper surface of soil layer 6 inside model box 4 should also be 17.6. The total weight of the weights is The weights are evenly placed on top of the laid soil layer 6.

[0238] Take a depth of 0.2m within the soil layer 6 of model box 4, and take the center of the test steel sheet pile 3 corresponding to this depth as the center. Take 3 measuring points on the circumferential measuring line 7 with a radius of 0.3m, and measure the displacement, strength, and compaction of the soil at these 3 measuring points.

[0239] The initial displacement, strength, and compaction test data of the soil at the three measuring points are recorded in Table 1:

[0240] Table 1

[0241]

[0242] Start hydraulic cylinder 2 to insert the test sheet pile 3 into the soil layer 6 of the model box 4 to a depth of 0.5m and a driving speed of 0.1m / min. Then, retract hydraulic cylinder 2 to pull out the test sheet pile 3. Immediately conduct soil displacement, strength, and compaction tests at the same measuring points. Record the data as shown in Table 2.

[0243] Table 2

[0244]

[0245] The displacement difference rates at each measuring point were calculated as follows: , , .

[0246] The intensity difference rates at each measuring point were calculated as follows: , , .

[0247] The density difference rates at each measuring point were calculated as follows: , .

[0248] The average displacement difference rate, average strength difference rate, and average density difference rate of this circumferential survey line 7 were calculated as follows: , .

[0249] The displacement fluctuation rate, strength fluctuation rate, and density fluctuation rate of this circumferential survey line 7 are calculated as follows: , .

[0250] The soil displacement disturbance evaluation index, strength disturbance evaluation index, and density disturbance evaluation index for this circumferential survey line 7 are calculated as follows: .

[0251] In practice, multiple circumferential survey lines 7 are taken at once, and the disturbance evaluation index of multiple circumferential survey lines 7 is calculated according to the above method. The weight coefficient of the comprehensive disturbance evaluation index is calculated according to the method of this invention as follows: Then the comprehensive disturbance evaluation index The set allowable value ,because Then, the hole formed after the test sheet pile 3 is pulled out needs to be treated.

[0252] After the test sheet pile 3 was extracted, clean medium-coarse sand with a particle size of 0.3-0.5 mm was immediately poured into the hole. A fine vibrator was used for layered compaction, vibrating once every 20 cm of filling until the hole was completely and densely filled. Finally, the hole was sealed with cement mortar. Twenty-four hours after the treatment, tests were conducted at the treated location and at a location in the undisturbed area. The test results are shown in Table 3 below.

[0253] Table 3

[0254]

[0255] The calculated recovery rates of density, penetration resistance, and unconfined compressive strength are as follows:

[0256] Following the above method, multiple locations are selected in the undisturbed area, and the weighting coefficients of the comprehensive quantitative evaluation index are calculated according to the method of this invention as follows: =0.3, =0.4, =0.3, calculate the comprehensive quantitative evaluation index. , ,according to The value indicates that the hole treatment quality is acceptable and no secondary treatment is required.

Claims

1. A simulation test method for the entire process of inserting and extracting steel sheet piles, characterized in that, Includes the following steps: S1: Construct a simulation device, which includes a reaction frame fixed on the ground. A hydraulic cylinder is installed downward in the middle of the reaction frame. The lower end of the hydraulic rod of the hydraulic cylinder is fixed to the upper end of the test sheet pile. A model box is set below the hydraulic cylinder. Collect soil samples from the depth unit downward at depth H on site. Lay the collected soil samples into the model box. Place several weights evenly on the upper surface of the remaining soil layers in the model box, except for the soil layer directly below the test sheet pile. The weights are used to represent the load above the equivalent depth unit soil. S2: Take m circumferential survey lines at a certain depth in the disturbed area of ​​the soil layer in the model box, and take n measuring points on each circumferential survey line to measure the displacement, strength, and compaction of each measuring point; the area whose horizontal distance from the longitudinal center axis of the test steel sheet pile is not greater than the thickness of the soil layer in the model box is considered as the disturbed area, and the area whose horizontal distance from the longitudinal center axis of the test steel sheet pile is greater than the thickness of the soil layer in the model box is considered as the undisturbed area; S3: The hydraulic cylinder slowly inserts the test sheet pile into the soil layer inside the model box, and then the hydraulic cylinder pulls the test sheet pile out of the soil layer inside the model box. S4: After the test sheet pile is pulled out, measure the displacement, strength, and density of each measuring point taken in step S2 again; S5: The first [unit / item] on a certain circumferential survey line Establishment of the difference rate index for each measurement point: The first on a certain circumferential survey line The displacement difference rate index at each measuring point is: The calculation formula is as follows: ； in, This indicates the first test sheet pile on a certain circumferential survey line before driving. Displacement test values ​​corresponding to each measuring point; This indicates the first [number] test sheet pile on a certain circumferential measuring line after the test sheet pile has been pulled out. Displacement test values ​​corresponding to each measuring point; The first on a certain circumferential survey line The intensity difference rate index at each measuring point is: The calculation formula is as follows: ； in, This indicates the first test sheet pile on a certain circumferential survey line before driving. The strength test values ​​corresponding to each measuring point; This indicates the first [number] test sheet pile on a certain circumferential measuring line after the test sheet pile has been pulled out. The strength test values ​​corresponding to each measuring point; The first on a certain circumferential survey line The density difference rate index at each measuring point is: Its calculation formula is ； in, This indicates the first test sheet pile on a certain circumferential survey line before driving. The density test value corresponding to each measuring point; This indicates the first [number] test sheet pile on a certain circumferential measuring line after the test sheet pile has been pulled out. The density test value corresponding to each measuring point; S6: Establishment of the average difference rate index for a certain circumferential survey line: The average displacement difference rate index for a certain circumferential survey line is calculated using the following formula: ； The average strength difference rate index for a certain circumferential survey line is calculated using the following formula: ； The average density difference rate index for a certain circumferential survey line is calculated using the following formula: ； S7: Establishment of volatility index for a certain circumferential test line: Establish volatility index C based on the difference rate index and the average difference rate index; The displacement fluctuation rate index for a certain circumferential measuring line is calculated from the displacement difference rate index and the average displacement difference rate index of n measuring points on this circumferential measuring line. The calculation formula is as follows: ； The intensity fluctuation rate index for a certain circumferential measurement line is calculated from the intensity difference rate index and the average intensity difference rate index of n measurement points on this circumferential measurement line. The calculation formula is as follows: ； The density fluctuation rate index for a certain circumferential measurement line is calculated from the density difference rate index and the average density difference rate index of n measurement points on this circumferential measurement line. The calculation formula is as follows: ； S8: Establishment of disturbance evaluation index for a certain circumferential survey line: To evaluate the displacement disturbance impact of sheet pile driving on the surrounding soil, the calculation formula is as follows: ； To evaluate the strength disturbance index of the impact of sheet pile driving on the surrounding soil, the calculation formula is as follows: ； To evaluate the compaction disturbance index of the impact of sheet pile driving on the surrounding soil, the calculation formula is as follows: ； S9: Calculate the weighting coefficients of the comprehensive disturbance evaluation index; the calculation of the weighting coefficients of the comprehensive disturbance evaluation index includes the following steps: S91: Calculate the average disturbance evaluation index for each of the m circumferential survey lines; the average disturbance evaluation index for each of the m circumferential survey lines is as follows: The calculation formulas are as follows: ； ； ； in, Represents the first of m circumferential survey lines. One circumferential survey line; S92: Calculate the jump value of the disturbance evaluation index; the jump value of the disturbance evaluation index includes the jump value of the displacement disturbance evaluation index. Intensity disturbance evaluation index jump value The jump value of the density disturbance evaluation index The calculation formulas are as follows: ； ； ； S93: Calculate the coefficient of variation The calculation formulas are as follows: ； ； ； S94: Calculate the weighting coefficients of the comprehensive disturbance evaluation index, and the calculation formulas are as follows: ； ； ； S10: Constructing a comprehensive disturbance evaluation index Set the allowed value N i When the comprehensive disturbance evaluation index Greater than the allowable value N i When this happens, the holes need to be treated; when the comprehensive disturbance evaluation index Not greater than the allowable value N i In this case, no treatment of the holes is required; the comprehensive disturbance evaluation index The structure is as follows: ； in, ; , , This is the disturbance evaluation index corresponding to any circumferential survey line.

2. The simulation test method for the entire process of steel sheet pile insertion and extraction according to claim 1, characterized in that, It also includes the following steps: S11: Select a location within the hole treatment area of ​​the model box, or select an undisturbed area within the model box. The location, for the area where the hole was treated and the undisturbed area. The soil at each location was measured for density, penetration resistance, and unconfined compressive strength. S12: Establish recovery rate indicators: The recovery rate indicators are established as follows: The density recovery rate is an index, and its calculation formula is as follows: ； The penetration resistance recovery rate index is calculated using the following formula: ； The unconfined compressive strength recovery rate is an index, and its calculation formula is as follows: ； Where, ρ 处 , qc 处 U 处 These represent the density, penetration resistance, and unconfined compressive strength of the selected location for the cavity treatment, respectively; ρ 未 , qc 未 U 未 These represent the density, penetration resistance, and unconfined compressive strength at a specific location in the undisturbed zone, respectively. S13: Calculate the weighting coefficient of the comprehensive quantitative evaluation index K; the calculation of the weighting coefficient of the comprehensive quantitative evaluation index K includes the following steps: S131: Calculate the average value of the recovery rate index; calculate separately. The recovery rate index at each location, then the average density recovery rate index Average value of penetration resistance recovery rate index Average value of unconfined compressive strength recovery rate The calculation formulas are as follows: ； ； ； in, express The first position in the position One location, ; S132: Calculate the jump value of the recovery rate index; jump value of the density recovery rate index. Penetration resistance recovery rate index jump value Unconfined compressive strength recovery rate index jump value The calculation formulas are as follows: ； ； ； S133: Calculate the coefficient of variation; coefficient of variation The calculation formulas are as follows: ； ； ； S134: Weighting coefficients of comprehensive quantitative evaluation indicators The calculation formulas are as follows: ； ； ； S14: Constructing a comprehensive quantitative evaluation index K: ; in ; , , for The data value corresponding to any position in the given positions; S15: Establish quality evaluation standards for hole treatment; if If the value is less than 0.3, it indicates poor hole treatment quality, requiring secondary treatment; if 0.3 ≤ If the value is less than 0.7, it indicates that the hole treatment quality is unqualified and secondary treatment is required; if 0.7 ≤ If ≤1.2, it indicates that the hole treatment is qualified; if A score >1.2 indicates excellent hole treatment.

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