Experimental Study On Mechanical Characteristics And Microstructure Of Improved Soft Soil

Soft soil is widely distributed in coastal and inland areas of China.With the rapid development of infrastructure construction,the infrastructure based on soft soil is increasing.Due to the poor engineering characteristics and inherent complexity of soft soil,it is very difficult to build roads in soft soil areas.However,the replacement or abandonment of soft soil will increase the cost,which requires the improvement of soft soil to meet the roadbed filling requirements.This paper summarizes the research status of soft soil improvement technology and improvement mechanism,based on a highway project in Yibin City,Sichuan Province.The field test,laboratory test and microstructure test of soft clay in the engineering area were carried out,and the basic parameters and microstructure characteristics of sand-doped improved soil were determined.The influence of sand mixing improvement on the engineering characteristics of soft soil is analyzed from the macro and micro perspectives,respectively,which proves the feasibility of sand mixing improvement and provides reference for soft soil engineering in the region.Through indoor and field tests of the original sample,the basic physical and mechanical parameters are obtained,and the physical and mechanical properties of soft soil are analyzed,which provides reference for the improvement of soft soil.According to the basic parameters of undisturbed soil and the improvement mechanism,the indoor test scheme was determined.The compaction,direct shear,unconfined compressive strength and compression tests were carried out on the remolded samples of modified soft soil to analyze the variation law of soil basic parameters before and after improvement,and the optimal sand mixing ratio was determined.The consolidated undrained triaxial tests were carried out on the remolded samples prepared by the soil before and after the improvement.By comparing the test results of the two,the effects of sand mixing improvement on the stress and strain relationship,pore pressure and strain relationship,Mohr circle and strength envelope of soft clay were explored.Mineral analysis and image scanning tests were carried out on the soil samples before and after improvement by using micro-test methods to obtain the mineral composition and scanning photos of the two samples.The microstructure is compared and analyzed,and the results of macroscopic physical mechanics test are verified from the microscopic point of view.