Effects Of Preloading Consolidation Time And Particle Size Distribution On Soil Shear Strength Of Granite Collapsing Hill

Soil layer of Granite collapsing hill is mainly composed of red soil layer, sandy soil layer and detritus layer, that shear strength is related to the stability of Granite collapsing hill wall, the study for soil shear strength of soil layer of Granite collapsing hill to help understand development of mechanism of Granite collapsing hill. This study chose three soil layers(red soil layer, sandy soil layer, detritus layer) of soil layer of typical Granite collapsing hill as the research object in Anxi County, Fujian Province. By preloading consolidation and redeploying particle size distribution, then took the soil samples to direct shear tests, studying the relationship between pre-press consolidation time and particle size distribution and soil shear strength, as well as analysing differences in soil layer of Granite collapsing hill soil shearing strength. The results showed that:(1) In addition to the moisture content of about 24%, the soil shear strength of red soil layer increased with the growth of the preloading consolidation time, but under the low moisture content, high moisture content and larger normal stress, the soil shear strength of red soil layer was on the decline as the growth of the preloading consolidation time; While normal stress was at the lowest and highest, there was no obvious relation between the soil shear strength of sandy soil layer and preloading consolidation time, at other two normal stress, there was relatively complex between the soil shear strength of sandy soil layer and preloading consolidation time; However, there was no relation between the soil shear strength of detritus layer and preloading consolidation time. In addition, the cohesive force of red soil increased with the growth of the preloading consolidation time, but the internal friction angle was on the decline; There was no obvious relation between cohesive force of sandy soil layer and detritus soil layer and the preloading consolidation time, only discrete degree of volatile, and internal friction angle was relatively stable.(2) Under the condition of the low moisture content (20% and 24%), soil shear strength of red soil layer was the largest, then was detritus layer, sandy soil layer was weakest; Under the condition of the high moisture content(when soil moisture content was above 28%), soil shear strength of red soil layer was minimal. In addition, soil internal friction angle of red soil layer gradually decreased with the growth of soil moisture content; Soil internal friction angle of sandy soil layer showed a trend that increased firstly, then decreased, finally went to increase; Soil internal friction angle of detritus layer increased firstly, finally dropped to zero. Soil cohesive force of red soil, sandy soil and detritus layer gradually decreased with the increasement of soil moisture content, and soil cohesive force of red soil layer was largest than other soil layers.(3) With the increasement of fine soil particle content, soil shear strength of red soil layer gradually increased, but the sandy soil layer was opposite exactly; Soil shear strength of detritus layer of original particle size distribution (detritus layer C) was larger than the other particle size distribution of detritus layer. In addition, there was little effect for soil internal friction angle of three soil layers(red soil layer, sandy soil layer and detritus layer) of granite collapsing hill by the particle size distribution, and showed stably; With the increasement of fine soil particle content, soil cohesive force of red soil layer gradually increased, but there was no obvious rule for sandy soil layer and detritus layer, but their degree of fluctuation was far. Fractal dimension of red soil layer particle size distribution was largest than sandy soil layer and detritus layer, there was no obvious effect for soil internal friction angle of three soil layers particle size distribution of granite collapsing hill by the fractal dimension, and cohesive force of red soil layer particle size gradation was positively related to fractal dimension, and there was no obvious relationship for soil cohesive force of sandy soil layer and detritus layer with fractal dimension.