Research On The Ground Subsidence Evolution Mechanism And Prediction Evaluation Based On Soil Structure

With the rapid development of economy and society,the long-term unreasonable exploitation of deep groundwater has become the main inducing factor of land subsidence.Land subsidence,as a kind of slow-changing geological hazard,has posed a serious threat to industrial and agricultural production,urban construction and operation,and sustainable economic and social development,due to its complex generation mechanism,wide impact,difficult prevention and control,and so on.In order to predict and control the environmental geological problems such as land subsidence induced by groundwater exploitation,it is necessary to deeply understand the macro-and micro-mechanism of consolidation settlement of rock and soil,and to establish a fluid-solid coupling numerical model that truly reflects the temporal and spatial evolution of groundwater flow field and land subsidence.Soil deformation has obvious elastic-plastic and hysteric characteristics,and is limited by soil micro-structure and strength.For a long time,people mainly study land subsidence from macroscopic level based on linear elastic constitutive model and ignore the characteristics of soil structure and plastic deformation,which will affect the simulation accuracy,and the grasp of the inherent law of soil deformation.Based on the above facts,the macro-micro mechanism of consolidation and settlement of structural soils are studied in this paper by theoretical analysis,laboratory macro-micro experiments,numerical simulation,and combination of macro-mechanical characteristics and micro-structural factors.The main contents are as follows.1.Focusing on the research status of ground subsidence at home and abroad,the microstructure of soil and its research status with macroscopic engineering characteristics,this paper establishes the research direction of this paper to explore the macroscopic and microscopic evolution mechanism of land subsidence.Analyze and summarize the field survey data and engineering background data,and clarify the vertical division of 18 engineering geological features and 4 aquifer groups within 800m of the study area.2.Construct hydrogeological exploration holes in the area,conduct indoor geotechnical tests on the rock samples,and obtain physical and chemical and hydrogeological parameters of each layer to evaluate and analyze the living environment of the soil in Dezhou;Scanning test,qualitative adjustment of the microstructure of the soil during the settlement process,combined with computer image processing technology,quantitative description of the temporal and spatial evolution characteristics of each microscopic structural element in the seepage consolidation,quantitative fitting of macroscopic mechanical parameters for later Provide a basis for the relationship with microstructural factors.3.Based on the basic theories of groundwater dynamics and geotechnical elastoplastic mechanics,based on groundwater dynamic data and ground subsidence observation data,the clay layer is selected as the elastic-ideal plastic Mohr-Coulomb constitutive model,and the aquifer is linear elastic Biot.Consolidation theory,using MIDAS GTS finite element numerical analysis software,establishes a macroscopic three-dimensional groundwater exploitation-ground subsidence coupling calculation model to simulate the spatial and temporal development of groundwater flow field and land subsidence in the area.4.The microstructure parameters which are significantly correlated with the permeability coefficient are obtained by a single correlation fitting method.The fitting equation is brought into the above-mentioned fluid-solid coupling numerical model.The sensitivity analysis of the microstructure parameters is used to quantitatively explore the mutual interaction between ground subsidence and microscopic factors.Mechanism of action,analysis and evaluation of the influence of structural parameters on land subsidence.