Study On Shear Strength Characteristics Of Unsaturated Loess In Zhangjiakou Area

In the arid and semi-arid zones of Zhangjiakou region,loess is widely distributed,and most natural and artificial slopes are in an unsaturated state.At present,the stability of the slope is often determined by the theory strength formula based on saturated soil.Such a design is very unreasonable,especially for temporary artificial slope,the design based on the strength of saturated soil will cause a lot of waste.The theory of unsaturated soil mechanics provides theoretical guidance for practical application of unsaturated soil slope engineering,and the development of computing technology also provides a new method for related research.Therefore,the reasonable analysis of the unsaturated shear strength distribution of loess in Zhangjiakou area is of great significance for the study of the unsaturated soil slope stability.An unavoidable problem in the study of soil slope stability is the determination of soil shear strength.Considering that most natural slopes are in the state of unsaturated soil,the design method of soil unsaturated soil strength has become a hot spot in engineering design research at present.Most of the research on shear strength of unsaturated soil is based on the theoretical formulas of unsaturated soil strength proposed by Bishop and Fredlund.Researchers have proposed a variety of unsaturated soil strength prediction formula,however,these formulas have a drawback is: need to know the inside of the soil matrix suction to determine the shear strength of soil,the work is often not desirable for practical engineering applications,so how to avoid in the calculation formula of matrix suction has become the focus of the researchers attention.In recent years,some scholars have proposed the study of shear strength theory of unsaturated soilusing the soil water characteristic curve database.This achievement has simplified the research of shear strength calculation method of unsaturated soil,built a practical bridge of unsaturated soil theory,and made the research of unsaturated soil theory get rid of the development dilemma of "academism" and become applied.However,specific engineering applications are not discussed in depth.Based on the engineering practice,the soil water characteristic curve and shear strength of the loess in Zhangjiakou area were further experimentally studied.On this basis,special design software for the stability of unsaturated soil slope was developed,making the application of unsaturated soil theory in engineering more specific.It makes the design more scientific and reasonable and brings great social and economic benefits to the project under the premise of guaranteeing the safety and quality of the project.