Research Of Loess Collapse Based On Catastrophe Theory

At present,the research on loess collapse mainly focus on the following aspects:(1)study the distribution,classification,damage mode,influencing factors,prevention measures of loess collapse;(2)research on the formation mechanism and movement state of loess collapse;(3)the stability of loess collapse;(4)numerical simulation including finite element and discrete element research on loess collapse.Although these research results have made a lot of contributions to the study of loess collapse,there are still many deficiencies in the numerical simulation,formation mechanism and stability research of loess collapse.In order to make a more systematic study on loess collapse,the paper analyzes the influencing factors and classification of loess collapse on the basis of summarizing the previous research results;combined with the finite element method,the numerical simulation of the formation process of loess collapse is carried out;Taking the tensile cracking-sliding loess collapse as an example,the stability of loess collapse was analyzed using rigid body limit equilibrium method,catastrophe theory,and catastrophe series method respectively,which provided new ideas for the study of the stability of other types of loess collapse.The main results are:(1)The influencing factors and classification of loess collapse are more comprehensively explained.The vertical joint development in internal factors,the role of water in external factors and human engineering activities are the main influencing factors.In the classification method of loess collapse,according to The classification of destruction modes is the most scientific and reasonable method.(2)By studying the process of loess slope collapse and instability,the formation of loess collapse is divided into seven stages,and the effect of the location of the crack and the moisture content of the slope soil on the loess collapse is analyzed.According to the analysis results of slope stress and strain,the formation mechanism of loess slope collapse and instability under the action of self-weight and water is revealed.(3)The limit equilibrium method was used to obtain the formula for calculating the minimum safety factor of the collapsed body;the cusp catastrophe theory was used to obtain the conditions of slope collapse and instability.The results show that the soil moisture content has a very important effect on the stability of the collapse body.(4)Because the model for analyzing the stability of collapsed bodies by catastrophe theory is relatively complicated and practical application is difficult,the paper establishes the stability criterion of the tensile cracking-sliding loess collapse based on the catastrophe series method obtained by combining catastrophe theory and fuzzy mathematics.Compared with the limit equilibrium method,the evaluation results are basically the same.This shows that as a new evaluation method,the catastrophe series method is simple to use and does not lose scientific.It has practical application value in the stability analysis of tensile cracking-sliding loess collapse.The above results show that this study enriches the existing research of loess collapse,which provides new theoretical support for the analysis of the collapse and instability of loess slopes,and plays a positive role in construction of loess slope projects and protecting the safety of people's lives and properties in loess areas.