Studies Of Curing And Tracing Method And Evolution Characteristics Of Cracks In Rock And Soil

Obtaining the geometric shapes and relevant parameters of cracks in rock and soil is the important micro-meso research content of their deformation and destruction.A low-cost laboratory test method for obtaining crack structure in certain stress(strain)status is meaningful for carrying out relavant research.Based on self-designed grouting device and modified triaxial apparatus,a series of tests on grouting quality are conducted,and the combined test system is used to recognize the cracks in multiple layers of remoulded soil samples with same properties.In contrast to the analysis of crack evolution in multiple layers of triaxial-CT tests,a comparison and an argumentation of the self-designed crack recognition scheme and crack evolution characteristics are conducted.The main results are as follows.(1)The modified urea-formaldehyde resin grout with 100:2 ratio of solution A and B is used in tests.A test system composed by self-designed pressure grouting device and modified triaxial apparatus is established.And based on the system,test principles,methods and procedures of resin grout grouted into and curing in soil's internal cracks are proposed.(2)Through the self-established test system,a series of section images in multiple layers of remoulded soil samples in different stress-strain status are obtained.Then the images are processed and analyzed by MATLAB and PCAS which can provide information for calculating geometric parameters of cracks.The evolution characteristics of samples' internal cracks from the middle of yield stage to post-peak are discussed based on the statistical mean values of each crack parameter.(3)Continuous observations on internal structure of 2 deep undisturbed soil samples are conducted under CT.And slice images of 5 typical layers are analyzed by several methods.The evolution characteristics of samples' internal cracks in overall stress-strain process are discussed based on the analysis results of the images of sample 4's typical layers.(4)Through comparison,despite its relatively low recognition scope and accuracy,all parameters of pre-existing internal cracks in each layer based on curing grout show the same tendency with that of CT tests from the middle of yield stage to post-peak,which indicates that the self-designed crack recognition scheme which is based on curing grout and the analysis of crack evolution according to the scheme's results is feasible and effective.