Study On Damage Model Of Cement-soil Based On Acoustic Emission Characteristic Parameters

In order to study the mechanical properties and internal failure law of cement-soil under uniaxial compression,in this paper,acoustic emission technology is introduced into the study on cement soil damage.Then establish the coupled model of damage constitutive model and acoustic emission parameters and mechanical parameters by study the acoustic emission and mechanical properties of cement soil under unconfined compression.The main research contents are as follows:(1)unconfined compressive tests are carried out,according to the "Water and Soil Mix Design Code"(JGJ T233-2011)to research cement soil unconfined compressive strength change law under different conditions including cement mixing ratio,different loading conditions.(2)when the unconfined compressive tests are conducted,meanwhile,using Sensor Highway ? SHM system to collect the acoustic emission parameters:the ring,the energy and amplitude.Then the variation rule of AE characteristic parameters in the process of cement-soil compressed is analyzed and Combined with the unconfined compression test,the parameters were analyzed comprehensively.(3)To study the damage characteristics of cement-soil under the condition of static load and the relationship between acoustic emission parameters and damage variables of cement soil,the stress-strain damage model of the cement soil is deduced.So,the damage model between acoustic emission parameters and mechanical parameters is established to further reveal the failure mechanism of the cement-soil structure.Based on the study of the strength and acoustic emission of cement soil at home and abroad,the achievements of this paper can be concluded as follows:the strength of cement-soil and the activity of cement-soil acoustic emission can be enhanced with the increase of cement content through the analysis on the performance of different cement content.The unconfined compressive strength of the soil,in a certain loading rate range,is increased and the acoustic emission activity in the cement-soil is increasingly fierce through the analysis on the performance of the soil under different loading rates.By analyzing the properties of cement-soil failure process,it can be induced that the change process of soil stress over time is roughly divided into four stages.Meanwhile,the acoustic emission parameter analysis shows the acoustic emission parameters are also divided into four stages and each stage is basically consistent with the mechanical parameters.Thus,the stress-strain damage constitutive model and the damage evolution expression of cement-soil under unconfined compression are deduced based on the previous research.The relationship between acoustic emission parameters and mechanical parameters is coupled by using time parameters as the intermediate variables.So,the relationship between the cumulative number of rings and the strain,stress and damage variables is obtained.This study combines the mechanical damage of cement soil with acoustic emission detection,which belongs to the research of cross and frontier.It also provides a basis for predicting,by using the change of AE parameters,the damage degree and damage condition of the cement-soil structure in the actual stress process and judging the instability damage of the structure and it is of great significance to apply acoustic emission technology to nondestructive testing of cement-soil structure in the future.