Study On The Influence Of The Content Of Coarse Grains On Static And Dynamic Strength Characteristics For Chuanxi Talus Mixed Soil

The western Sichuan region is located in the transitional zone among the Sichuan Basin and the Qinghai-Tibet Plateau and the Hengduan Mountains.The geological environment is very complicated,and there are a lot of special geological structures and special rock and soil.There is a large amount of talus mixed soil in this area.This soil is formed after a series of rolling and sliding processes.During this period,besides pressing,shearing,rubbing,rubbing and other physical effects and erosion,the soil also experienced a lot of freezing and thawing and other chemical effects.With these effects repeated,the coarse and fine particles mixed with a complex structure soil are formed.The study of earthquakes such as earthquakes in Sichuan shows that many landslides are sliding along the slumps of sand and gravel and clay particles.In addition,with the development of infrastructure in Sichuan Province,talus mixed soil high-filled roadbed in the form of mountain excavation has become the common roadbed and the basic form of the western Sichuan mountainous roads and buildings.However,due to the large change in coarse particles and the uneven water content in the mixed soil,there are some problems in the operation process.Therefore,the physical properties of the mixed soils in western Sichuan are clarified,and their mechanical properties are studied in depth.In order to evaluate the stability of the collapsing soils and provide reference for the disaster prevention and control of such soils,it is very theoretically and practically valuable in engineering.The technical route of this paper is the conventional geotechnical test-the static triaxial test of the talus mixed soil-the dynamic triaxial test of the talus mixed soil-the theoretical analysis.In this paper,a large number of experimental studies were carried out on the basis of the technical route.Based on the coarse grain content as the controlling factor,the large-scale dynamic and static triaxial tests were carried out on the mixed soil of the western Sichuan area.And the static and dynamic properties of mixed soils were analyzed.The main research contents and achievements are as follows:1.In the same landslide,three kinds of talus mixed soil in the landslide are collected as soil samples,and the physical properties are not significant in their fine particles.However,the content of coarse particles in the mixed soils varied greatly,and it was found that the coarse particle content(particle size>5mm)of the mixed soil was varied in the range of 20%?76%.2.Three kinds of talus mixed soil were sieved,and fine particles with particle size<5mm were subjected to triaxial test.It has been found that the static and dynamic parameters of the three soil samples with particle size<5mm are almost indistinguishable.3.The influence of the coarse particles content with particle size>5mm on the internal friction angle of the mixed soil strength index is 41%-62%.The internal friction angle of the mixed soil will increase with the increase of the coarse particles content.Among them,when the coarse particles content with particle size>5mm of less than 41%,the fine particles play a major role in the mixed soil,and the coarse particles are wrapped by the fine particles,in this stage the friction angle growth slow;When the coarse particles content with particle size>5mm is higher than 41%,the cohesive soil between the coarse particles decreases and the friction contact between the coarse particles increases.At this stage,the friction angle of the soil increases rapidly.When the coarse particle content of particle size>5mm exceeds 62%,coarse particles begin to form coarse particles skeleton.The coarse particles occupy the dominant position,so at this stage the increase in coarse particle content on the soil friction angle of the growth effect is reduced.4.The influence of the coarse particles content with particle size>5mm on the cohesion or bite force of the strength index of the talus mixed soil in the western Sichuan area is 41%?62/%.The cohesive force or bite force of soil decreases with the increase of coarse grains content firstly,and then its numerical value increases.When the coarse particles content of particle size>5mm is less than 41%,the c value in the talus mixed soil is provided by the fine particles.Under the condition that the average density of the soil samples is the same,the increase of the coarse particles content makes the density of the fine particles lower,the c value shows a slowly descending trend.When the coarse particles content of particle size>5mm is more than 41%,the talus mixed soil shows the properties of the two kinds of particles,and the coarse particles begin to undergo a large amount of contact.As the coarse particles increased,the c value begins to decline rapidly.Coarse particles begin to form a coarse particles skeleton when the coarse particles content of particle size>5 mm is more than 62%,and coarse particles are sufficiently contacted at this stage,and coarse particles are occluded at this time.The c value(bite force)begins to show a certain upward trend with coarse particles increase.