Study On Influencing Factors And Failure Mode Of Tensile Strength Of Remolded Loess Based On Unconfined Penetration Test

The unconfined penetration test method is widely used in the testing and research of soil tensile strength of rock and soil materials.In this paper,the unconfined penetration test method is used to explore the influence of multi-factor orthogonal and single factor independent action on the tensile strength of remolded loess.Combined with the discrete element numerical simulation software,Analyze the crack change of the sample during the failure process and the relationship between the tensile stress and the penetration depth curve.The conclusion is as follows:The test results show that:(1)Under the comprehensive influence of multiple factors,the sensitivity of loess tensile strength to test factors is water content,disk diameter,dry density,sample preparation method,the ratio of height to diameter and loading rate.Among them,water content,dry density and disk diameter have significant effects on the tensile strength of remolded loess.(2)The tensile strength of remolded loess decreases with the increase of water content and increases with the increase of dry density.With the increase of disk diameter,static pressure layer 3 is more suitable to be used as the sample preparation method of the unconfined penetration test.When the loading rate is kept at 1mm stroke min,the tensile data is the most stable,which can be used as the loading rate of the unconfined penetration test.In the multi-factor standard of the unconfined penetration test,the reasonable range of the ratio of disk diameter to height-diameter ratio is 12.3-20.5.Under single factor,the reasonable range of the ratio of disk diameter to height-diameter ratio is 13.5-18.8.(3)The failure of remolded loess in the unconfined penetration test can be divided into three modes:compression failure,tensile failure and tension-compression coupling failure,and each mode corresponds to the corresponding failure mode.The damage forms are two petals,three petals and multi petals,in which two petals and three petals are the main ones,and the multi petals failure is judged to be squeeze failure.(4)The numerical simulation results of unconfined penetration test of remolded loess are consistent with those of laboratory test,and the failure process of the unconfined penetration test can be reproduced.The research results will help to further deepen the understanding of loess mechanics,promote the development of loess tensile testing technology,improve the testing theory and method of loess tensile strength,and provide scientific support for the cooperative prevention and control of loess geological disasters.