The Spatial Variation Research For Mass Density And Permeability Characteristics Of Gravel Soil From Slope Table

Accumulation of gravel soil as a kind of common geological body widely exists in the central south and northwest regions of China, and geological disasters often induced due to rainfall erosion or engineering activities resulting in huge economic losses and casualties for our country, such as landslide and debris flow, etc. However,the composition complex and the irregular structure distribution of gravel soil have brought great difficulties to the research of its engineering properties and mesoscopic structure. This paper, the research slope of gravel soil is selected from zhao mountain in Hunan province, based on image processing technology and the indoor experimental to study space variation characteristic of the mass density of gravel soil,using the high magnification optical microscope to observe the mesoscopic pore characteristics of fine clay of gravel soil, based on Darcy’s theorem to make indoor saturated permeability test of gravel soil, and using CT tomography technology to obtain the pore characteristics of gravel soil specimen, is tried to study the correlation between the pore characteristics of gravel soil and its permeability coefficient, and to deepen our understanding of this complex material, and then provide reference for similar engineering problems about rainfall landslides of gravel soil. The main research results are summarized as follows:1. The stone content of the slope surface ranged from 49.75% to 77.63%, and along the slope face has a tendency to reduce, the diameter range in 0~10 mm of particles concentration along the slope face increased significantly, located in the20~60 mm diameter range of gravel content down along the slope distribution obviously decreased, but particle size range of 10~20 mm of crushed stone content does not change significantly along the slope; Roundness distribution are mainly in the range of 0.7~0.9, the average of its cumulative is 77.3%; The average of block length axis t ratio lies between 1.4 ~ 1.497, and along the slope facing the trend of smaller. The complexity of the gravel along the slope face had a tendency to increase.2. There is a quadratic curve relationship between porosity and moisture content in fine clay soil under the same quality, and the experiment soil has the best compaction when the moisture content is 10.41%; the Pore number, the pore complexity and the pore variability decreases with the increase of the moisture content variation degree, its indicate that the smaller of the pore moisture content, thehigher level of distortion and the more complex of pore, the more pore number and more beneficial to infiltration for surface water.3. Through analysis orthogonal experimental results shows that: the biggest influence of pore characteristics and permeability coefficient of gravel soil is stone content, and the influence of dry density and gradation to gravel soil porosity follow stone content. The gravel soil porosity, pore number and permeability coefficient of gravel soil are creasing along with the increase of stone content, but pore variability and pore complexity were reduced along with the increase of stone content. And combination of characteristics of gravel soil porosity to analysis the relationship of the permeability coefficient and gravel soil pore characteristics, it found the permeability coefficient exponential reduced along with the increasing of the pore characteristic value.