Analysis Of Tensile Strength Characteristics Of Loess And Its Influence On Slope Stability

China has vast territory,and there is a wide range of loess distribution area,of which the Loess Plateau is the largest loess accumulation on earth.There are many researches on the mechanical properties of loess,most of which focus on the study of the shear strength of loess,and because of the non-attention in engineering practice,the research on tensile strength is relatively few.Although the tensile strength of loess is not high,the formation and development of geological disasters such as landslide,ground crack,slope peeling and engineering accidents are related to the tensile strength characteristics of loess.Therefore,the study of loess tensile strength not only has realistic engineering significance,but also has important soil mechanics value.Taking Q3 loess of Xi ’ an in Shaanxi province as the research object,this paper carries out the following work: the tensile strength and deformation characteristics of undisturbed loess and reconstructed loess under different conditions are measured by laboratory test,and the Combination Strength theory suitable for loess in this paper is put forward,and the theoretical critical depth of tensile cracks at the top of loess slope is calculated.The calculation model of slope stability including tensile strength is established,and an example is calculated and analyzed.The tensile strength test results of uniaxial tensile test and axial fracturing test show that:(1)in terms of strength characteristics,the tensile strength of undisturbed loess is between 8.89 k Pa-83.1k Pa;the remolded loess is between 8.57 k Pa-205.69 k Pa.With the increase of water content,the tensile strength of loess decreases with the exponential function with the e base;(2)in terms of deformation characteristics,with the increase of water content and the decrease of dry density,the variation law ofstress-strain curve of specimen shows different geometrical models,and the type of specimen failure develops from elastic deformation to plastic deformation.Based on the analysis and comparison of the test results,the hyperbolic combined strength theory is applicable to the loess used in this paper,on the basis of which,the joint hyperbolic strength theory,the Mohr-Coulomb strength criterion and the maximum tensile stress obtain the critical depth value of the tensile crack at the top of the slope,and by analyzing the characteristics of the gestation and development of the loess slope landslide,the plane shear model of Loess landslide is put forward,and the formula of slope safety coefficient including tensile strength is established,and the analysis shows that:(1)The greater the tensile strength of slope soil,the greater the safety coefficient of slope;(2)when the slope top crack is farther away from the plateau edge,the effect of tensile strength on slope stability is smaller.Based on the results obtained in this paper,the tensile strength value of loess has an important influence on slope stability,and the plane shear failure model of loess slope and its slope stability evaluation method proposed in this paper have certain reference significance for the calculation of slope stability by combining tensile strength.