Pile-soil dynamic response simulation test method

Abstract

The invention relates to the technical field of civil engineering, in particular to a pile-soil dynamic response simulation test method which comprises the following steps: acquiring a soil body parameter, a pile body parameter and a construction parameter of a target engineering site; establishing a pile-soil power system generalization model according to a preset similarity ratio, and respectively determining a soil body parameter of the sand soil stratum, a pile body parameter of the simulation pile, and a first power loading parameter and a second power loading parameter of a loading system; preparing a pile-soil system according to the soil body parameters of the sand soil stratum and the pile body parameters of the simulation pile, controlling the pile-soil system to carry out vibration pile sinking and vibration pile pulling based on the first power loading parameter and the second power loading parameter, and monitoring test data in the vibration pile sinking and vibration pile pulling process, and analyzing to obtain a pile-soil dynamic response simulation analysis result. Therefore, the problems of tedious work, high cost and difficulty in accurate description of research on the dynamic response rule between the pile and the soil are solved, and the dynamic response rule between the pile and the soil under different conditions can be efficiently and accurately simulated.

Description

Technical Field

[0001] The present application relates to the field of civil engineering technology, and in particular to a pile-soil dynamic response simulation test method. Background Art

[0002] In recent years, with the gradual saturation of the development and utilization of shallow and medium-layer underground space in my country, more and more urban underground spaces have begun to show a "high-density" development state with high building volume ratio and high coverage rate. Underground engineering construction in a limited and complex environment is very likely to cause road collapse, damage to existing buildings (structures) and underground pipelines, and other problems, seriously threatening people's lives and property and the safety of land space.

[0003] The construction technology of vibrating steel sheet piles has the characteristics of strong adaptability to the strata, small working space requirements, and convenient construction. It has been widely used in foundation pit support, cofferdam and other projects. The principle of the construction technology of vibrating steel sheet piles is to soften the soil around the piles through high-frequency vibration (25-65 Hz), so that the compact state between the soil particles is destroyed, thereby reducing its cohesion and friction, so that the piles can be smoothly inserted or pulled out. However, unreasonable construction parameters (excitation force, frequency, amplitude, etc.) will aggravate the scope of soil damage or the degree of impact, especially in strata with fine particles and strong permeability such as sand.

[0004] In the related technologies, the main research results and shortcomings of the vibration sinking and extraction steel sheet pile technology are as follows: (1) The related technologies mainly focus on the driveability of the pile, the pile-soil contact characteristics during the pile sinking process, and the vertical and horizontal bearing capacity of the pile body after it is buried in the soil. However, there is almost no related research work on the equally critical pile extraction process, lacking a sufficient theoretical basis to optimize the construction process and parameters. (2) The research in the related technologies is concentrated on clay strata, and there is relatively little research on sandy strata. Sand and clay have significant differences in particle size, shape, and intergranular friction characteristics. They have the characteristics of loose particles, strong permeability, and strong friction, which affect the interaction mechanism between piles and soil. (3) The research objects in the related technologies are mainly concentrated on pipe piles, and there is relatively little research on steel sheet piles (U-shaped, H-shaped, and Z-shaped sections). There are significant differences between pipe piles and steel sheet piles in terms of structure, material, and interaction mechanism with soil. The research results focusing on pipe pile types cannot be directly applied to steel sheet pile types.

[0005] In addition, the dynamic response of the pile-soil system in the construction of vibration pile sinking and extraction is affected by the loading mode, pile type characteristics and basic properties of the soil. The relevant technologies are often based on simplified mechanical models, which are difficult to accurately reflect the complex pile-soil interaction process and the dynamic mechanical behavior of the soil. When using numerical simulation methods, the large deformation of the soil around the pile during the pile sinking process is difficult to solve, and the problem of non-convergence is prone to occur in the calculation; when simulating pile extraction, the deformation recovery process of the soil is also difficult to restore. At the same time, the soil around the pile is prone to liquefaction or softening under the action of high-frequency vibration, which also puts high requirements on the accuracy of the soil constitutive equation and the performance of the computer. When using field tests, due to the heterogeneity of the rock and soil and the complex influencing factors during the test process, the test results are highly discrete; at the same time, due to the limitations of construction site conditions, the comprehensiveness and accuracy of the on-site monitoring data are also difficult to guarantee. In addition, although some indoor tests have been carried out, there is almost no research on the whole process of vibration sinking and extraction of steel sheet piles and the impact on the soil around the piles. The monitoring of important indicators such as the stress-deformation characteristics of steel sheet piles and the liquefaction damage characteristics of sand is not comprehensive and accurate enough, which needs to be solved urgently. Summary of the invention

[0006] The present application provides a pile-soil dynamic response simulation test method to solve the problem that the study of the pile-soil response law during vibration sinking-pulling is cumbersome, costly and difficult to accurately characterize. The method can efficiently and accurately simulate the pile-soil dynamic response law under different types of soil layers, steel sheet piles with different cross-sectional forms and excitation parameters.

[0007] The first aspect of the present application provides a pile-soil dynamic response simulation test method, which is applied to a pile-soil dynamic response simulation test system, wherein the pile-soil dynamic response simulation test system comprises: a loading system, a pile-soil system, a monitoring system and a data acquisition system, wherein the pile-soil system comprises: a pile top fixture, a model pile, a model box and a sandy soil layer, wherein one end of the pile top fixture is connected to a conversion joint in the loading system, and the other end of the pile top fixture is connected to the model pile, so that the vibration drill in the loading system is vertically connected to the model pile to form a whole; the sandy soil layer is arranged in the model box; the monitoring system comprises first to fourth accelerometers, first to fourth earth pressure boxes, first to second borehole pressure gauges and first to fifth strain gauge groups, the first accelerometer is arranged at the connection between the conversion joint and the pile top fixture, and the second to fourth accelerometers are arranged on the surface of the sandy soil layer; the first earth pressure box and the second earth pressure box are arranged at a first depth position below the surface of the sandy soil layer, and the first earth pressure box and the first earth pressure box are arranged at a first depth position below the surface of the sandy soil layer. The second soil pressure box is located on both sides of the model pile and is symmetrical. The third soil pressure box and the fourth soil pressure box are set at the second depth position below the surface of the sand layer, and the third soil pressure box and the fourth soil pressure box are located on both sides of the model pile and are symmetrical. The first hole pressure gauge and the second hole pressure gauge are located on both sides of the model pile and are symmetrical. Each strain gauge group includes three strain gauges, and the three strain gauges are located on the same horizontal line. The distance between the first strain gauge group and the bottom of the model pile is a first preset distance, and the distance between the second strain gauge group and the fifth strain gauge group and the bottom of the model pile is a second preset distance. The second strain gauge group is located on the inner side of the model pile, and the fifth strain gauge group is located on the outer side of the model pile. The distance between the third strain gauge group and the bottom of the model pile is a third preset distance, and the distance between the fourth strain gauge group and the bottom of the model pile is a fourth preset distance, and the fourth preset distance is greater than the third preset distance, the third preset distance is greater than the second preset distance, and the second preset distance is greater than the first preset distance. The method includes the following steps: Obtain soil parameters, pile parameters and construction parameters of the target project site; A generalized model of a pile-soil dynamic system is established according to a preset similarity ratio, and soil parameters of the sandy soil layer and pile body parameters of the simulated pile are determined according to the generalized model of the pile-soil dynamic system and soil parameters and pile body parameters of the target engineering site, and a first dynamic loading parameter and a second dynamic loading parameter of the loading system are determined according to the generalized model of the pile-soil dynamic system and construction parameters; The pile-soil system is prepared according to the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile, and the pile-soil system is controlled by the loading system to perform vibration pile sinking and vibration pile pulling based on the first dynamic loading parameter and the second dynamic loading parameter. The monitoring system is used to monitor the test data at different times and different pile sinking depths during the vibration pile sinking and vibration pile pulling process, and the test data is analyzed by the data acquisition system to obtain the simulation analysis result of the pile-soil dynamic response.

[0008] Optionally, in some embodiments, the controlling the pile-soil system to perform vibration pile sinking and vibration pile extraction through the loading system based on the dynamic loading parameter includes: Based on the first dynamic loading parameter, the simulated pile of the pile-soil system is controlled by the loading system to perform vibration pile sinking until the bottom of the simulated pile reaches a preset position, and the vibration pile sinking is stopped. When the stopping time is longer than the preset time, the loading system is controlled to perform vibration pile pulling based on the second dynamic loading parameter, and the simulated pile bottom is pulled out from the sandy soil layer, and the vibration pile pulling is stopped.

[0009] Optionally, in some embodiments, after stopping the vibration pile pulling, the following steps are performed: Generate a test end reminder instruction, and issue a reminder according to the test end reminder instruction.

[0010] Optionally, in some embodiments, before controlling the pile-soil system to perform vibration pile sinking and vibration pile extraction through the loading system based on the first dynamic loading parameter and the second dynamic loading parameter, the method further includes: Obtaining adjustment instructions for the first power loading parameter and the second power loading parameter; According to the adjustment instruction, the adjusted first power loading parameter and the second power loading parameter are determined.

[0011] Optionally, in some embodiments, after using the monitoring system to monitor the test data at different times and different pile sinking depths during the vibration pile sinking and vibration pile pulling process, and analyzing the test data by the data acquisition system to obtain the pile-soil dynamic response simulation analysis results, the method further includes: Comparing the pile-soil dynamic response simulation analysis result with a preset simulation analysis result to obtain an error analysis result, and generating a test parameter correction instruction according to the error analysis result; According to the test parameter correction instruction, the soil parameters of the sandy soil layer, the pile body parameters of the simulated pile, and the first dynamic loading parameters and the second dynamic loading parameters of the loading system are corrected to obtain new soil parameters of the sandy soil layer, the pile body parameters of the simulated pile, and the first dynamic loading parameters and the second dynamic loading of the loading system, and the steps of preparing the pile-soil system according to the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile, and controlling the pile-soil system to perform vibration pile sinking and vibration pile pulling through the loading system based on the first dynamic loading parameters and the second dynamic loading parameters are re-executed. Optionally, in some embodiments, the test data includes at least one of vibration acceleration, soil pressure, pore water pressure and pile body strain.

[0012] Optionally, in some embodiments, the soil parameters include at least one of density, compactness, and saturation.

[0013] Optionally, in some embodiments, the pile body parameters include: at least one of material, cross-sectional size, length, density, and elastic modulus.

[0014] Optionally, in some embodiments, the construction parameters include: at least one of exciting force, frequency, and amplitude.

[0015] Optionally, in some embodiments, the first dynamic loading parameter includes: at least one of vibration frequency, exciting force, direction, action time, sinking distance, and pile sinking rate; The second dynamic loading parameter includes at least one of vibration frequency, exciting force, direction, action time, rising distance, and pile pulling rate.

[0016] Therefore, this application has the following beneficial effects: (1) This application can directly simulate the dynamic response law between piles and soil under different types of soil layers, different cross-sectional forms of steel sheet piles and excitation parameters, thus solving the problems of large workload, high cost and complex influencing factors in field tests.

[0017] (2) The present application can directly simulate the soil liquefaction and strength attenuation process when sinking piles with different excitation parameters, the stress deformation characteristics of the pile body, and the soil deformation and strength recovery process when pulling out the piles, thus solving the problems of difficulty in simulating soil deformation and poor reliability of results in numerical simulation of vibration sinking and pulling out steel sheet piles.

[0018] (3) The present application can efficiently and accurately record data such as vibration acceleration, pore water pressure, soil pressure, and pile deformation during the pile sinking and pulling process, thereby solving the problem of incomplete and low-precision data collection of pile-soil dynamic response during the vibration sinking and pulling of steel sheet piles, and failing to accurately reveal the dynamic response mechanism of the vibration sinking and pulling of steel sheet piles and the soil.

[0019] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 A schematic diagram of a pile-soil dynamic response simulation test system provided according to an embodiment of the present application; Figure 2 A flowchart of a pile-soil dynamic response simulation test method provided according to an embodiment of the present application; Figure 3 A schematic diagram of the implementation steps of a pile-soil dynamic response simulation test system provided according to an embodiment of the present application; Figure 4 A schematic diagram of a test sand particle gradation curve provided according to an embodiment of the present application; Figure 5 A schematic diagram of a pile-soil system provided according to an embodiment of the present application; Figure 6 A schematic diagram of the cross-sectional dimensions of a model pile provided according to an embodiment of the present application; Figure 7 A schematic diagram of a pile top clamp provided according to an embodiment of the present application; Figure 8 A schematic diagram of soil sensor arrangement according to an embodiment of the present application; Fig. 9 The figure is a schematic diagram of the arrangement of pile body sensors according to one embodiment of the present application. DETAILED DESCRIPTION

[0021] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0022] The following describes the pile-soil dynamic response simulation test method of an embodiment of the present application with reference to the accompanying drawings. In view of the problems mentioned in the above background technology that the study of the response law between piles and soil during vibration sinking and pulling is cumbersome, costly and difficult to accurately characterize, the present application provides a pile-soil dynamic response simulation test method, in which the method includes: obtaining the soil parameters, pile body parameters and construction parameters of the target engineering site, and establishing a generalized model of the pile-soil dynamic system according to a preset similarity ratio, and determining the soil parameters of the sandy layer and the pile body parameters of the simulated pile according to the generalized model of the pile-soil dynamic system and the soil parameters and pile body parameters of the target engineering site, respectively, and determining the first dynamic loading parameters and the second dynamic loading parameters of the loading system according to the generalized model of the pile-soil dynamic system and the construction parameters, and preparing a pile-soil system according to the soil parameters of the sandy layer and the pile body parameters of the simulated pile, and controlling the pile-soil system to perform vibration pile sinking and vibration pile pulling through the loading system based on the first dynamic loading parameters and the second dynamic loading parameters, and using a monitoring system to monitor the test data at different times and different pile sinking depths during vibration pile sinking and vibration pile pulling, and analyzing the test data through a data acquisition system to obtain a simulation analysis result of the pile-soil dynamic response. This solves the problem that studying the response law between pile and soil during vibration sinking and pulling is cumbersome, costly and difficult to accurately characterize. It can efficiently and accurately simulate the dynamic response law between pile and soil under different types of soil layers, steel sheet piles with different cross-sections and excitation parameters.

[0023] Before introducing the pile-soil dynamic response simulation test method of the embodiment of the present application, the pile-soil dynamic response simulation test system is first introduced. Figure 1 As shown, the pile-soil dynamic response simulation test system includes 10: a loading system 100, a pile-soil system 200, a monitoring system 300 and a data acquisition system 400.

[0024] The loading system 100 includes: a vibrator, a hydraulic system, a lifting system, a support frame and a conversion joint.

[0025] The pile-soil system 200 comprises: a pile top fixture, a model pile, a model box and a sandy soil layer, wherein one end of the pile top fixture is connected to a conversion joint in a loading system, and the other end of the pile top fixture is connected to the model pile, so that the vibration drill in the loading system is vertically connected to the model pile to form a whole; the sandy soil layer is arranged in the model box.

[0026] The monitoring system 300 comprises: first to fourth accelerometers, first to fourth earth pressure boxes, first to second borehole pressure gauges and first to fifth strain gauge groups, wherein the first accelerometer is arranged at the connection between the conversion joint and the pile top clamp, and the second to fourth accelerometers are arranged on the surface of the sandy soil layer; the first earth pressure box and the second earth pressure box are arranged at a first depth position below the surface of the sandy soil layer, and the first earth pressure box and the second earth pressure box are located on both sides of the model pile and are symmetrical parts, the third earth pressure box and the fourth earth pressure box are arranged at a second depth position below the surface of the sandy soil layer, and the third earth pressure box and the fourth earth pressure box are located on both sides of the model pile and are symmetrical parts; the first borehole pressure gauge and the second borehole pressure gauge are arranged at a second depth position below the surface of the sandy soil layer, and the third earth pressure box and the fourth earth pressure box are located on both sides of the model pile and are symmetrical parts; The force gauges are located on both sides of the model pile and are symmetrical parts; each strain gauge group includes three strain gauges, and the three strain gauges are located on the same horizontal line, the distance between the first strain gauge group and the bottom of the model pile is a first preset distance, the distance between the second strain gauge group and the fifth strain gauge group and the bottom of the model pile is a second preset distance, and the second strain gauge group is located on the inner side of the model pile, the fifth strain gauge group is located on the outer side of the model pile, the distance between the third strain gauge group and the bottom of the model pile is a third preset distance, and the distance between the fourth strain gauge group and the bottom of the model pile is a fourth preset distance, wherein the fourth preset distance is greater than the third preset distance, the third preset distance is greater than the second preset distance, and the second preset distance is greater than the first preset distance.

[0027] Among them, the first preset distance, the second preset distance, the third preset distance and the fourth preset distance may be preset by a user, may be obtained through a limited number of experiments, or may be obtained through a limited number of computer simulations, and are not specifically limited here.

[0028] The data acquisition system 400 includes: a handheld dynamic signal test analyzer, a dynamic and static strain test collector, and a signal test analysis system.

[0029] Specifically, Figure 2 Flow chart of the pile-soil dynamic response simulation test method provided in an embodiment of the present application.

[0030] like Figure 2 As shown, the pile-soil dynamic response simulation test method includes the following steps: In step S101, soil parameters, pile parameters and construction parameters of the target engineering site are obtained.

[0031] Among them, soil parameters include: at least one of density, compactness, and saturation; pile body parameters include: at least one of material, cross-sectional size, length, density, and elastic modulus; construction parameters include: at least one of exciting force, frequency, and amplitude.

[0032] Specifically, the embodiments of the present application ascertain the geological conditions and physical and mechanical parameters of the rock and soil at the engineering site through engineering survey means or based on the construction site survey data; and clarify the construction parameters (exciting force, frequency, amplitude, etc.) and pile body parameters (pile body material, size, strength, pile type, etc.) of the vibration sinking-extraction piles according to the construction process plan.

[0033] In the actual implementation process, the embodiment of the present application can ensure that the simulation test is closer to the actual engineering conditions based on the acquired soil parameters, pile body parameters and construction parameters of the target engineering site, thereby improving the reliability and practicality of the test results.

[0034] In step S102, a generalized model of the pile-soil dynamic system is established according to a preset similarity ratio, and the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile are determined according to the generalized model of the pile-soil dynamic system and the soil parameters and pile body parameters of the target engineering site, and the first dynamic loading parameters and the second dynamic loading parameters of the loading system are determined according to the generalized model of the pile-soil dynamic system and the construction parameters.

[0035] Among them, the preset similarity ratio can be pre-set by the user, can be obtained through a limited number of experiments, or can be obtained through a limited number of computer simulations. No specific limitation is made here. The first dynamic loading parameter includes: at least one of vibration frequency, exciting force, direction, action time, sinking distance, and pile driving rate; the second dynamic loading parameter includes: at least one of vibration frequency, exciting force, direction, action time, sinking distance, and pile pulling rate.

[0036] Specifically, the embodiment of the present application is based on similarity theory, comprehensively considering factors such as the size of the test model, material type, loading method, and measurement point arrangement, to determine the similarity ratio between the test model and the prototype, that is, a preset similarity ratio, including: geometric similarity, material similarity, motion / dynamic similarity, and establish a generalized model of the pile-soil dynamic system.

[0037] Based on the similarity ratio between the generalized model of the pile-soil dynamic system and the preset one, the pile body parameters (material, cross-sectional size, length, density, elastic modulus, etc.) of the simulated pile, the soil parameters (density, compactness, saturation, etc.) of the sandy soil layer and the vibration hammer parameters (vibration frequency, amplitude, exciting force, etc.) of the loading system are determined. The first loading parameters of the vibration pile (vibration frequency f, exciting force F, direction D, action time t, sinking distance s, pile sinking rate, etc.) are determined according to the vibration hammer parameters. v 沉 ) and the second loading parameters of vibration pile extraction (vibration frequency f, exciting force F, direction D, action time t, rising distance s, pile extraction rate v 拔 ).

[0038] In step S103, a pile-soil system is prepared according to the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile, and the pile-soil system is controlled by the loading system to perform vibration pile sinking and vibration pile pulling based on the first dynamic loading parameter and the second dynamic loading parameter. The monitoring system is used to monitor the test data at different times and different pile sinking depths during the vibration pile sinking and vibration pile pulling process, and the test data is analyzed by the data acquisition system to obtain the simulation analysis results of the pile-soil dynamic response.

[0039] The test data includes at least one of vibration acceleration, soil pressure, pore water pressure and pile body strain.

[0040] Specifically, after obtaining test parameters such as the soil parameters of the sandy soil layer, the pile body parameters of the simulated pile, and the vibration hammer parameters of the loading system, a pile-soil dynamic response simulation test system is established, and a pile-soil system is prepared according to the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile. After the sandy soil layer is prepared and the pile-soil dynamic response simulation test system is connected, the pile-soil system is controlled by the loading system to perform vibration pile sinking and vibration pile extraction based on the first dynamic loading parameter and the second dynamic loading parameter.

[0041] Further, in some embodiments, the pile-soil system is controlled by the loading system to perform vibration pile sinking and vibration pile extraction based on the dynamic loading parameters, including: based on the first dynamic loading parameter, the loading system is controlled to perform vibration pile sinking on a simulated pile of the pile-soil system until the bottom of the simulated pile reaches a preset position, and the vibration pile sinking is stopped; and when the stop time is longer than the preset time, the loading system is controlled to perform vibration pile extraction based on the second dynamic loading parameter, and the bottom of the simulated pile is extracted from the sandy soil layer, and the vibration pile extraction is stopped.

[0042] Among them, the preset position and preset time can be pre-set by the user, can be obtained through a limited number of experiments, or can be obtained through a limited number of computer simulations, and are not specifically limited here. Preferably, in order to ensure that the soil disturbed by pile driving is fully consolidated, the preset time is 48 hours.

[0043] Specifically, after the pile-soil dynamic response simulation test system is prepared, the vibration pile sinking process is simulated and monitored. Specifically, the conversion joint and the support stand are adjusted, the position of the pile-soil system is determined, and the loading parameters of the vibration pile sinking (vibration frequency) are set. f , exciting force F ,direction D , Action time t , sinking distance s , pile sinking rate v 沉 ), start the vibration pile driving process, and record the vibration acceleration at different times and pile driving depths during the vibration pile driving process ( a )、Earth Pressure(E )、pore water pressure( P ) and pile strain ( ε ) data, and the pile driving test is completed after the bottom of the simulated pile sinks to the preset position.

[0044] The time interval between vibration pile extraction and vibration pile driving tests shall be no less than 48 hours to ensure that the soil disturbed by pile driving is fully consolidated. The dynamic loading parameter values ​​of vibration pile extraction and vibration pile driving tests shall be kept consistent. The vibration pile extraction process shall be started, and the vibration acceleration, soil pressure, pore water pressure and pile body strain data at different times and pile end depths during the vibration pile extraction process shall be recorded. The pile extraction test shall be ended after the pile bottom is simulated to be pulled out of the soil.

[0045] Optionally, in some embodiments, after stopping the vibration pile extraction, it includes: generating a test end reminder instruction, and giving a reminder according to the test end reminder instruction.

[0046] It is understandable that the test end reminder instruction can allow relevant personnel to understand the test progress in a timely manner and reasonably arrange subsequent work, such as equipment disassembly, data collation and analysis, etc., to avoid wasting time waiting for the end of the test and improve test efficiency.

[0047] During the actual implementation process, the embodiments of the present application can provide test end reminder instructions by means of visual reminders, auditory reminders, and information push. For example, an indicator light is set on the device or console. When the test end reminder instruction is generated, the indicator light lights up or flashes to attract the attention of relevant personnel. A red indicator light indicates that the test is over, and a green indicator light indicates that the test is proceeding normally.

[0048] Optionally, in some embodiments, before controlling the pile-soil system to perform vibration pile driving and vibration pile extraction through the loading system based on the first power loading parameter and the second power loading parameter, it also includes: obtaining adjustment instructions for the first power loading parameter and the second power loading parameter; and determining the adjusted first power loading parameter and the second power loading parameter according to the adjustment instructions.

[0049] It can be understood that the embodiments of the present application can also characterize the soil liquefaction and strength attenuation process when sinking piles with different excitation parameters, the stress deformation characteristics of the pile body, and the soil deformation and strength recovery process when pulling out the piles by adjusting the first dynamic loading parameter and the second dynamic loading parameter, thereby solving the problems of difficult modeling and unreliable results in numerical simulation. In addition, during the test, if it is found that the equipment is operating abnormally or there is a safety hazard, the operating load of the equipment can be reduced by adjusting the dynamic loading parameters to prevent equipment damage.

[0050] During the actual implementation process, when it is necessary to adjust the first dynamic loading parameter and the second dynamic loading parameter, the relevant personnel or the control system can generate an adjustment instruction, and adjust the first dynamic loading parameter and the second dynamic loading parameter according to the adjustment instruction to measure the vibration acceleration, pore water pressure, soil pressure, and pile deformation data of the pile-soil system under different dynamic loading parameters.

[0051] Optionally, in some embodiments, after using a monitoring system to monitor the test data at different times and different pile driving depths during vibration pile driving and vibration pile pulling, and analyzing the test data through a data acquisition system to obtain a pile-soil dynamic response simulation analysis result, it also includes: comparing the pile-soil dynamic response simulation analysis result with a preset simulation analysis result to obtain an error analysis result, and generating a test parameter correction instruction based on the error analysis result; according to the test parameter correction instruction, correcting the soil parameters of the sandy layer, the pile body parameters of the simulated pile, and the first dynamic loading parameters and the second dynamic loading parameters of the loading system to obtain new soil parameters of the sandy layer, the pile body parameters of the simulated pile, and the first dynamic loading parameters and the second dynamic loading of the loading system, re-executing the steps of preparing a pile-soil system according to the soil parameters of the sandy layer and the pile body parameters of the simulated pile, and controlling the pile-soil system through the loading system based on the first dynamic loading parameters and the second dynamic loading parameters to perform vibration pile driving and vibration pile pulling. It is understandable that after generating the pile-soil dynamic response simulation analysis results, the deviations in the model can be found by comparing the pile-soil dynamic response simulation analysis results with the preset simulation analysis results, and then the soil parameters, pile body parameters and dynamic loading parameters can be corrected to make the model closer to the actual engineering situation. The corrected parameters can improve the model's prediction ability for the pile-soil system under different working conditions, providing a more accurate basis for subsequent construction.

[0052] Specifically, the embodiments of the present application can preset simulation analysis results of the pile-soil system during vibration pile driving and vibration pile extraction based on engineering experience, relevant specifications or test data of previous similar projects, such as the expected range of pile top displacement, the expected distribution of pile body stress, etc., compare the simulation analysis results of the pile-soil dynamic response with the preset simulation analysis results, calculate the error size to obtain the error analysis result, analyze the main cause of the error based on the error comparison result, and determine the parameters that need to be corrected and their correction direction based on the error cause, generate correction instructions, and re-execute the test based on the correction execution. Specifically, correct at least one of the soil parameters, pile body parameters, first dynamic loading parameters and second dynamic loading parameters, and re-prepare the pile-soil system based on the corrected parameters, and control the pile-soil system to perform vibration pile driving and vibration pile extraction to obtain new simulation results, and regenerate the error analysis results until the error analysis results are within an acceptable range.

[0053] In order to enable relevant technical personnel in the field to further understand the pile-soil dynamic response simulation test method implemented in this application, it is described in detail below in conjunction with specific embodiments.

[0054] like Figure 3 As shown, Figure 3 It is a schematic diagram of the implementation steps of the pile-soil dynamic response simulation test method proposed in the embodiment of the present application.

[0055] The embodiment of the present application takes an open excavation foundation pit project of a city's underground comprehensive pipeline corridor as an example. Due to the narrow construction space and complex surrounding environment, the project uses Larsen steel sheet piles as the foundation pit support structure.

[0056] Step (a), based on the existing engineering site survey data and combined with engineering geological survey, it was found that there was a 12 m thick fine sand layer distributed within the construction impact area. The soil layer was saturated with water and had a high density. The physical and mechanical parameters of the fine sand layer were obtained through drilling data and laboratory tests, as shown in Table 1. Table 1 is a table of physical and mechanical parameters of soil.

[0057] Table 1

[0058] A high-frequency hydraulic vibratory hammer is used on site to complete the steel sheet pile construction, as shown in Table 2. Table 2 is a technical parameter table of the high-frequency hydraulic vibratory hammer, including the main technical parameters of the steel sheet pile construction.

[0059] Table 2

[0060] The model of Larsen steel sheet pile is SP-IV, and the cross section is U-shaped. The dimensions are 400 mm wide, 170 mm high, 16.0 mm thick, and the cross-sectional area is 96.99 cm2.

[0061] Taking into account the size of the indoor test site, equipment performance, material parameters, monitoring point layout and other factors, the model test was carried out under 1 g normal gravity conditions. The similarity ratio between the generalized model of the pile-soil dynamic system and the prototype is shown in Table 3. Table 3 is the similarity ratio table between the generalized model of the pile-soil dynamic system and the prototype.

[0062] Table 3

[0063] It should be noted that when the ratio of the foundation width of the generalized model of the pile-soil dynamic system to the average particle size of the foundation material is greater than 233, the influence of the particle size effect on the test results is less than 1%, which can be basically ignored.

[0064] Step (b), based on the generalized model of the pile-soil dynamic system, determine the pile body parameters (material, cross-sectional dimensions, length, density, elastic modulus, etc.), soil parameters (density, compactness, saturation, etc.) and vibration hammer parameters (vibration frequency, exciting force, etc.), see Table 3. The amplitude and exciting force are related to the dynamic loading test equipment. For this test equipment, when the vibration frequency is 45 Hz, the amplitude is about 2 mm and the exciting force is about 0.5 kN. The sand was taken from the construction site of the vibrating steel sheet pile, and its particle size distribution is as follows: Figure 4 ; In order to obtain a model pile that meets the design similarity ratio, aluminum-magnesium alloy is selected as the pile body material. The vibration, pile sinking and pile extraction processes in the model test are realized through the loading system; Step (c): construct a pile-soil dynamic response simulation test system 10 according to the determined test materials and parameters. The pile-soil dynamic response simulation test system 10 is composed of four subsystems: a loading system 100, a pile-soil system 200, a monitoring system 300, and a collection system 400. Figure 1 The loading system 100 includes a vibrator, a hydraulic system, a lifting system, a support frame and a conversion joint; the pile-soil system 200 includes a model pile, a model box, a soil layer and a pile top fixture; the monitoring system 300 includes a vibration acceleration sensor, an earth pressure box, a pore water pressure sensor and a strain gauge; the acquisition system 400 includes a dynamic signal test analyzer and a dynamic and static strain test acquisition instrument; the specific parameters of each subsystem are as follows: (1) Loading system 100. A hydraulically driven vibration drill can provide a vertical (axial) exciting force with a maximum frequency of 150 Hz. The vibration drill uses the deadweight of the model pile and the static pressure / tension applied to the top of the pile to achieve the pile sinking and pulling process. The vibration drill and the model pile are connected as a whole through a conversion joint. (2) Pile-soil system 200. The model foundation was prepared in a square plexiglass model box of 1 m × 1 m × 1 m (X, Y and Z directions), as shown in Figure 5 . The internal joints of the model box are sealed and fixed with a steel frame on the outside to meet the test strength requirements. The distance between the pile axis and the model box wall is more than 20 times the effective pile diameter, and the boundary effect can be ignored; the model foundation is prepared by the alluvial method. The model foundation is prepared in layers (5 layers of 1 m, 1 layer of 0.2 m) to control the relative density (Dr) of the model foundation. First, the model box is filled with pure water, and then the known weight of each layer of sand is poured into the model box and tamped. In the case of Dr = 60%, the mass of sand used to prepare each layer is about 330 kg.

[0065] The cross-section of the model pile is 100 mm wide, 43 mm high, 4 mm thick, and 50 cm long. Figure 6 shown.

[0066] The pile top clamp is welded from a flange and a miniature bench vise, and is compatible with the size of the conversion joint, see Figure 7 . The outer diameter of the flange is 160 mm, the inner diameter is 18 mm, the thickness is 15 mm, the center distance of the screw holes is 125 mm, and the flange has the size and hole position that match the drill pipe joint. The jaw width of the miniature bench vise is 60 mm, and the maximum clamping thickness is 30 mm (adjustable). The miniature bench vise is welded to the flange and is located on the same axis. The sonic vibration drill is vertically connected to the model pile through the pile top clamp to form a whole; (3) Monitoring system 300. Vibration acceleration sensors (marked as M1-M4) are arranged on the surface of the sand layer near the connection between the conversion joint and the pile top clamp and the model box wall. During the preparation of the sand layer, the sensors are arranged when the soil layer is laid to the corresponding depth, such as Figure 8 As shown. Four earth pressure boxes (marked as E1-E4) were arranged, divided into two groups along the longitudinal direction, located on both sides of the model pile, and symmetrically distributed. The buried depths were 10 cm and 30 cm below the surface of the foundation soil, respectively, and the radial distance from the model pile was 10*δ (δ is the thickness of the model pile), 4 cm. Two pore pressure sensors (marked as P1 and P2) were buried, one group was arranged along the longitudinal direction, located on both sides of the model pile, and symmetrically distributed, with a buried depth of 20 cm and a radial distance from the model pile of 10*δ, 4 cm.

[0067] The strain gauges (marked as S1-S15) are evenly pasted on the web and flange of the model pile and arranged in a symmetrical manner. Fig. 9 . The 15 strain gauges are divided into five groups, and each group of strain gauges is located on the same horizontal line. The first group S1-S3, the second group S4-S6, the third group S7-S9, the fourth group S10-S12, the distance between each group of strain gauges and the bottom of the pile is 2cm, 6cm, 14cm and 30cm respectively. The fifth group S13-S15 is 14cm away from the bottom of the pile, and is symmetrically arranged on both sides of the model pile with the second group. Apply sealant around the strain gauges for waterproofing.

[0068] (4) Acquisition system 400. The acceleration signal is analyzed and processed using the signal test and analysis system software. The soil pressure, pore water pressure and strain signals are collected by the dynamic and static strain test acquisition instrument. The stress and strain signals generated during the model test are analyzed and processed using the dynamic and static strain test and analysis system software.

[0069] Step (d), after the soil has been left to stand for 48 hours, the pile-soil dynamic response simulation test system is connected, and the vibration frequency f, exciting force F, inclination angle θ, action time t, sinking distance s and pile sinking rate v of the vibration pile sinking are set to 45 Hz, 0.5 kN, 270°, 20 s, 40 cm and 2 cm / s respectively, and the vibration pile sinking process is started. The vibration acceleration (a), soil pressure (E), pore water pressure (P) and pile body strain (ε) data at different times (0-20 s) and pile sinking depths (0-40 cm) during the vibration pile sinking process are recorded. After the bottom of the pile sinks 40 cm into the sand layer, the pile sinking test is completed.

[0070] Step (e), 48 hours after the vibration pile driving test, the vibration pile pulling test is started. The vibration frequency f, exciting force F, inclination angle θ, action time t, sinking distance s and pile driving rate v of the vibration pile pulling are: 45Hz, 0.5kN, 90°, 20s, 40cm and 2cm / s respectively. The vibration acceleration (a), soil pressure (E), pore water pressure (P) and pile body strain (ε) data at different times (0~20s) and pile end depths (0~40cm) during the vibration pile pulling process are recorded. The test ends when the pile end depth is 0 cm.

[0071] Therefore, the embodiment of the present application can simulate the dynamic response law between pile and soil under various working conditions by adjusting the steel sheet pile type, soil type and its parameters, excitation parameters, etc. in the pile-soil dynamic response simulation test system, thereby solving the problems of cumbersome process and difficulty in collecting test data in field tests; and, according to the vibration acceleration, pore water pressure, soil pressure, and pile deformation data measured by the monitoring system, the embodiment of the present application can characterize the soil liquefaction and strength attenuation process when sinking piles with different excitation parameters, the stress deformation characteristics of the pile body, and the soil deformation and strength recovery process when pulling out the pile, thereby solving the problems of difficult modeling and unreliable results in numerical simulation; in addition, the embodiment of the present application fills the technical gap in the related technology that it is impossible to accurately simulate and reveal the response law and action mechanism between pile and soil during vibration sinking and pulling, and provides a reliable test system and method for conducting full-process simulation and monitoring of dynamic response between pile and soil in indoor sites.

[0072] According to the pile-soil dynamic response simulation test method proposed in the embodiment of the present application, by acquiring the soil parameters, pile body parameters and construction parameters of the target engineering site, and establishing a generalized model of the pile-soil dynamic system according to a preset similarity ratio, the soil parameters of the sandy layer and the pile body parameters of the simulated pile are respectively determined according to the generalized model of the pile-soil dynamic system and the soil parameters and pile body parameters of the target engineering site, and the first dynamic loading parameters and the second dynamic loading parameters of the loading system are determined according to the generalized model of the pile-soil dynamic system and the construction parameters, and a pile-soil system is prepared according to the soil parameters of the sandy layer and the pile body parameters of the simulated pile, and the pile-soil system is controlled by the loading system to perform vibration pile sinking and vibration pile extraction based on the first dynamic loading parameters and the second dynamic loading parameters, and the test data at different times and different pile sinking depths during the vibration pile sinking and vibration pile extraction are monitored by a monitoring system, and the test data are analyzed by a data acquisition system to obtain the simulation analysis results of the pile-soil dynamic response. This solves the problem that studying the response law between pile and soil during vibration sinking and pulling is cumbersome, costly and difficult to accurately characterize. It can efficiently and accurately simulate the dynamic response law between pile and soil under different types of soil layers, steel sheet piles with different cross-sections and excitation parameters.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0074] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0075] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0076] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0077] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0078] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A pile-soil dynamic response simulation test method, characterized in that: The pile-soil dynamic response simulation test method is applied to a pile-soil dynamic response simulation test system, which includes: a loading system, a pile-soil system, a monitoring system and a data acquisition system, wherein the pile-soil system includes: a pile top fixture, a model pile, a model box and a sandy soil layer, wherein one end of the pile top fixture is connected to the conversion joint in the loading system, and the other end of the pile top fixture is connected to the model pile, so that the vibration drill in the loading system is vertically connected to the model pile to form a whole; the sandy soil layer is arranged in the model box; the monitoring system includes first to fourth accelerometers, first to fourth earth pressure boxes, first to second borehole pressure gauges and first to fifth strain gauge groups, the first accelerometer is arranged at the connection between the conversion joint and the pile top fixture, and the second to fourth accelerometers are arranged on the surface of the sandy soil layer; the first earth pressure box and the second earth pressure box are arranged at a first depth position below the surface of the sandy soil layer, and the first earth pressure box and the second earth pressure box are located on both sides of the model pile, and are symmetrical parts, the third earth pressure box and the fourth earth pressure box are arranged at the second depth position below the surface of the sand layer, and the third earth pressure box and the fourth earth pressure box are located on both sides of the model pile and are symmetrical parts; the first hole pressure gauge and the second hole pressure gauge are located on both sides of the model pile and are symmetrical parts; each group of strain gauges includes three strain gauges, and the three strain gauges are located on the same horizontal line, the distance between the first strain gauge group and the bottom of the model pile is a first preset distance, the distance between the second strain gauge group and the fifth strain gauge group and the bottom of the model pile is a second preset distance, and the second strain gauge group is located on the inner side of the model pile, the fifth strain gauge group is located on the outer side of the model pile, the distance between the third strain gauge group and the bottom of the model pile is a third preset distance, the distance between the fourth strain gauge group and the bottom of the model pile is a fourth preset distance, the fourth preset distance is greater than the third preset distance, the third preset distance is greater than the second preset distance, and the second preset distance is greater than the first preset distance, wherein the method comprises the following steps: Obtain soil parameters, pile parameters and construction parameters of the target project site; A generalized model of a pile-soil dynamic system is established according to a preset similarity ratio, and soil parameters of the sandy soil layer and pile body parameters of the simulated pile are determined according to the generalized model of the pile-soil dynamic system and soil parameters and pile body parameters of the target engineering site, and a first dynamic loading parameter and a second dynamic loading parameter of the loading system are determined according to the generalized model of the pile-soil dynamic system and construction parameters; The pile-soil system is prepared according to the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile, and the pile-soil system is controlled by the loading system to perform vibration pile sinking and vibration pile pulling based on the first dynamic loading parameter and the second dynamic loading parameter. The monitoring system is used to monitor the test data at different times and different pile sinking depths during the vibration pile sinking and vibration pile pulling process, and the test data is analyzed by the data acquisition system to obtain the simulation analysis result of the pile-soil dynamic response.

2. The method according to claim 1, characterized in that The method of controlling the pile-soil system to perform vibration pile sinking and vibration pile extraction through the loading system based on the dynamic loading parameters includes: Based on the first dynamic loading parameter, the simulated pile of the pile-soil system is controlled by the loading system to perform vibration pile sinking until the bottom of the simulated pile reaches a preset position, and the vibration pile sinking is stopped. When the stopping time is longer than the preset time, the loading system is controlled to perform vibration pile pulling based on the second dynamic loading parameter, and the simulated pile bottom is pulled out from the sandy soil layer, and the vibration pile pulling is stopped.

3. The method according to claim 1, characterized in that After stopping the vibration pile extraction, including: Generate a test end reminder instruction, and issue a reminder according to the test end reminder instruction.

4. The method according to claim 1, characterized in that: Before controlling the pile-soil system to perform vibration pile sinking and vibration pile extraction through the loading system based on the first dynamic loading parameter and the second dynamic loading parameter, the method further includes: Obtaining adjustment instructions for the first power loading parameter and the second power loading parameter; According to the adjustment instruction, the adjusted first power loading parameter and the second power loading parameter are determined.

5. The method according to claim 1, characterized in that After using the monitoring system to monitor the test data at different times and different pile sinking depths during the vibration pile sinking and vibration pile pulling process, and analyzing the test data through the data acquisition system to obtain the pile-soil dynamic response simulation analysis results, the method further includes: Comparing the pile-soil dynamic response simulation analysis result with a preset simulation analysis result to obtain an error analysis result, and generating a test parameter correction instruction according to the error analysis result; According to the test parameter correction instruction, the soil parameters of the sandy soil layer, the pile body parameters of the simulated pile, and the first dynamic loading parameters and the second dynamic loading parameters of the loading system are corrected to obtain new soil parameters of the sandy soil layer, the pile body parameters of the simulated pile, and the first dynamic loading parameters and the second dynamic loading of the loading system, and the steps of preparing the pile-soil system according to the soil parameters of the sandy soil layer and the pile body parameters of the simulated pile, and controlling the pile-soil system to perform vibration pile sinking and vibration pile pulling through the loading system based on the first dynamic loading parameters and the second dynamic loading parameters are re-executed.

6. The method according to claim 1, characterized in that The test data includes at least one of vibration acceleration, soil pressure, pore water pressure and pile body strain.

7. The method according to claim 1, characterized in that The soil parameters include: at least one of density, compactness and saturation.

8. The method according to claim 1, characterized in that The pile body parameters include: at least one of material, cross-sectional size, length, density, and elastic modulus.

9. The method according to claim 1, characterized in that: The construction parameters include: at least one of exciting force, frequency, and amplitude.

10. The method according to claim 1, characterized in that The first dynamic loading parameter includes: at least one of vibration frequency, exciting force, direction, action time, sinking distance, and pile sinking rate; The second dynamic loading parameter includes at least one of vibration frequency, exciting force, direction, action time, rising distance, and pile pulling rate.

Images