CN-121977953-A - Soft clay cyclic re-consolidation characteristic test method and device

CN121977953ACN 121977953 ACN121977953 ACN 121977953ACN-121977953-A

Abstract

The application discloses a method and a device for testing the cyclic re-consolidation characteristic of soft clay, wherein the method mainly comprises the steps of dynamically adjusting lateral boundary constraint conditions of a sample according to independent control logic while applying an axial cyclic load so as to simulate an actual stress path; and synchronously collecting the axial deformation, the lateral strain field, the pore water pressure and the acoustic emission signals of the sample, further calculating the characteristic parameters in real time based on the data of the multiple physical fields, and automatically deciding the test process according to the preset criteria. The soft clay cycle reconsolidation characteristic test method and device provided by the application can simulate the field boundary condition more truly, and realize the multi-dimensional state monitoring and intelligent test control from macroscopic to microscopic.

Inventors

ZHANG BAOFENG
LAI YONGQING
Yao Menghao
HE BEN
HUAN CAIYUN
SHI RUILONG
HUANG GUOXIANG
GAO PENG
Chen Hairuo

Assignees

中国电建集团华东勘测设计研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20260203

Claims (10)

1. The soft clay cyclic re-consolidation characteristic test method is characterized by comprising the following steps of: S1, preparing a soft clay sample and establishing a boundary environment, wherein the soft clay sample is prepared and placed in a test environment capable of dynamically adjusting lateral constraint stiffness and drainage conditions; s2, initializing test parameters, namely setting an amplitude sequence, frequency and waveform function of an axial cyclic load, and simultaneously configuring a dynamic boundary adjusting program which is related to an axial load time sequence and has independent control logic so as to define an evolution path of boundary conditions along with a loading process; S3, synchronously collecting coupling loading and multi-field data, namely applying an axial cyclic load according to the setting of S2, synchronously regulating and controlling boundary conditions in real time according to a dynamic boundary regulating program, and continuously collecting macroscopic mechanical response data and microscopic physical field signals of a sample; S4, state feature extraction and intelligent decision, namely calculating a group of feature parameters of the internal structure evolution of the quantifiable sample in real time based on the S3 data, comparing the feature parameters with a preset multi-level criterion, and automatically deciding a test process, wherein the test process comprises maintenance loading, level jump or safe termination.
2. The method for testing the cyclic resolidification property of soft clay according to claim 1, wherein, The dynamic boundary adjusting program in S2 comprises at least one preset boundary condition change mode, wherein the mode is that the boundary constraint rigidity is reinforced in a piecewise linear way along with the cycle time, or the dynamic change of the lateral stress coefficient under a specific stress path is simulated.
3. The method for testing the cyclic resolidification property of soft clay according to claim 2, wherein, When the dynamic boundary adjusting program is executed, the average pore water pressure of a plurality of previous cycle periods is used as a feedback signal, and when the average value continuously deviates from a preset interval, an incremental PID algorithm is adopted to adjust the boundary constraint stiffness set value of the next time window so as to indirectly control the drainage condition of the sample.
4. The method for testing the cyclic resolidification property of soft clay according to claim 1, wherein, The macroscopic mechanical response data collected in the step S3 comprises an axial stress-strain hysteresis curve and accumulated plastic strain; The microscopic physical field signals include a continuous lateral strain distribution along the specimen height acquired by distributed fiber optic sensing, and a micro-fracture event signal located by an acoustic emission sensor array.
5. The method for testing the cyclic resolidification property of soft clay according to claim 4, wherein, The characteristic parameters calculated in S4 include a structural uniformity index, which is defined as a coefficient of variation of the lateral strain distribution, and a damage activity index, which is defined as a product of the sum of the emission event energy release and the event count rate in a unit time.
6. The method for testing the cyclic resolidification property of soft clay according to claim 5, wherein, The multistage criteria in S4 include: The structural uniformity index is continuously lower than the threshold A and maintains a predetermined cycle Zhou Cishi, triggering a reconsolidation stability determination; triggering injury acceleration early warning when the injury activity index exceeds a threshold B and the moving average value of the injury activity index is in a monotonically rising trend; and when the reconsolidation stabilization and damage acceleration signals are received, the safe termination based on damage early warning is preferentially executed.
7. The method for testing the cyclic resolidification property of soft clay according to claim 1, wherein, And after the step S1 and before the step S2, setting a system interaction response calibration step, namely applying a detection load pulse with an increasing amplitude, synchronously recording the boundary pressure and deformation response of the sample so as to establish initial compensation parameters of a dynamic boundary adjustment program, and correcting the influence of system flexibility and nonlinearity on a test result.
8. A soft clay cyclic resolidification characteristic testing device for performing the soft clay cyclic resolidification characteristic testing method of any one of claims 1 to 7, comprising: a rigid base (1) is internally integrated with a drainage channel and a pore water pressure measuring interface; the loading plate (2) is arranged opposite to the rigid base (1) and is integrated with an axial force sensor (6); The servo electric cylinder (3) is in transmission connection with the loading plate (2) and is used for accurately outputting axial displacement and load; the composite boundary constraint ring (4) is arranged around the sample and consists of an inner porous lining plate and an outer intelligent material driving ring; A multifunctional driver (5) coupled with the composite boundary constraint ring (4) for outputting a controllable magnetic field to the intelligent material drive ring to continuously adjust its equivalent stiffness; The fiber bragg grating strain sensing chain (8) is arranged on the side surface of the sample and comprises at least 8 measuring points arranged along the height direction of the sample; A micro pore water pressure sensor (9) buried in the middle of the sample; a broadband acoustic emission sensor (10) mounted on the rigid base (1); the central controller (11) integrates data acquisition and processing functions, is in communication connection with the servo electric cylinder (3), the multifunctional driver (5), the axial force sensor (6), the fiber bragg grating strain sensing chain (8), the micro pore water pressure sensor (9) and the broadband acoustic emission sensor (10) through an industrial bus, and is internally provided with a control algorithm for realizing the steps of the method.
9. The soft clay cycling and re-consolidation characteristic testing device according to claim 8, wherein, The intelligent material driving ring in the composite boundary constraint ring (4) is made of magnetorheological elastomer materials, and the shearing modulus can be continuously and reversibly adjusted within the range of 1 MPa-100 MPa under the action of a magnetic field provided by the multifunctional driver (5).
10. The soft clay cycling and re-consolidation characteristic testing device according to claim 8 or 9, wherein, The measuring points of the fiber bragg grating strain sensing chain (8) are equidistant, the distance is less than or equal to 15 mm, the measuring base length is 10 mm, and the lateral deformation of 1 micro-strain level can be distinguished.

Description

Soft clay cyclic re-consolidation characteristic test method and device Technical Field The invention belongs to the technical field of geotechnical engineering test, and particularly relates to a soft clay cycle re-consolidation characteristic test method and device. Background In the field of geotechnical engineering, the method is important to accurately master the heavy consolidation characteristic of soft clay under the action of cyclic load and evaluate engineering problems such as long-term settlement of foundation caused by traffic load, seabed stability caused by wave load and the like. The indoor test is a main means for researching the dynamic characteristics of soil, and the reliability of the test result directly influences the rationality and the safety of engineering design. Therefore, the development of the test method and the test device which can simulate the field stress condition more truly and acquire the response information of the more comprehensive soil body has important engineering practice significance. Existing soft clay cyclic resolidification test methods typically place the test specimens in a consolidation apparatus at fixed boundary conditions (e.g., fully rigid or fully flexible), then apply an axial cyclic load and observe its deformation and pore pressure response. The method has obvious limitations that firstly, the fixed boundary condition is difficult to reflect the complex lateral constraint change caused by soil layer variation, stress history or adjacent construction activities in the actual foundation, so that the test condition is severely disjointed with the engineering reality. And secondly, the test process mainly depends on single macroscopic indexes such as axial deformation, average pore water pressure and the like to judge, and the defect of effective monitoring on deformation fields, localized phenomena and microstructure damage evolution in the sample is overcome, so that the judgment basis for the reconsolidation state is insufficient, and irreversible damage accumulation in the soil body is difficult to early warn. In addition, the progress and termination of the test process are mostly dependent on preset fixed cycle times or artificial experience judgment, and an intelligent decision mechanism based on the real-time state of the sample is lacking, so that the degree of automation of the test and the objectivity of the result are affected. Therefore, a method and a device for testing the soft clay cycle reconsolidation characteristics are needed to overcome the defects caused by immobilization of boundary conditions, simplification of monitoring indexes and dependence of test process judgment on preset or empirical mode in the prior art, so as to provide a soft clay cycle reconsolidation characteristic testing scheme which can simulate actual working conditions more truly, capture the internal state evolution of soil more comprehensively and realize intelligent test control. Disclosure of Invention The invention provides a soft clay cycle re-consolidation characteristic test method and a device for solving the technical problems, which concretely adopts the following technical scheme: A soft clay cyclic re-consolidation characteristic test method comprises the following steps: S1, preparing a soft clay sample and establishing a boundary environment, wherein the soft clay sample is prepared and placed in a test environment capable of dynamically adjusting lateral constraint stiffness and drainage conditions; s2, initializing test parameters, namely setting an amplitude sequence, frequency and waveform function of an axial cyclic load, and simultaneously configuring a dynamic boundary adjusting program which is related to an axial load time sequence and has independent control logic so as to define an evolution path of boundary conditions along with a loading process; S3, synchronously collecting coupling loading and multi-field data, namely applying an axial cyclic load according to the setting of S2, synchronously regulating and controlling boundary conditions in real time according to a dynamic boundary regulating program, and continuously collecting macroscopic mechanical response data and microscopic physical field signals of a sample; S4, state feature extraction and intelligent decision, namely calculating a group of feature parameters of the internal structure evolution of the quantifiable sample in real time based on the S3 data, comparing the feature parameters with a preset multi-level criterion, and automatically deciding a test process, wherein the test process comprises maintenance loading, level jump or safe termination. Further, the dynamic boundary adjusting procedure in S2 includes at least one preset boundary condition variation mode, where the boundary constraint stiffness is piecewise linearly strengthened with the cycle, or simulates the dynamic variation of the lateral stress coefficient under the specific stress path. Further, whe