Relationship between Soil Scale Distribution Parameters of Debris Flow Source Soils and Cohesive Strength
Particle gradation governs soil mechanical properties,e.g.,cohesion.The content of fine particles in soils,such as clay content,plays a decisive role in generating cohesive strength of soils.Although soil particle gradation can be characterized by specific grain sizes,e.g.,D50,it does not avoid issues in soil mechanics such as soils tagged with the same characteristic particle size but distinct geophysical properties.Antecedent research proposed a soil scale distribution model(SSDM)by two parameters μ and Dc to define soil particle gradation.This model proved to be an acceptable expression of soil particle gradation characteristics,but there was unknown for its geophysical interpretation as well as its relation to soil cohesive strength.In this study,laboratory tests were conducted to characterize the soil particle graduation using SSDM;the changes in cohesive strength of soil samples were investigated under the conditions of different moisture contents and scale parameters;then geophysical relationship between granularity composition/scale distribution parameter,moisture content and cohesion was carefully concluded.(1)The scale distribution parameter(μ)increases with the increases of fine particle contents in soils,exhibiting a fine exponential function relationship.(2)As fine particle content increased,the cohesive strength in soils rapidly increased initially and then gradually stabilized.The relationship between the cohesive strength(c)and the scale parameter(μ)could be quantitatively expressed using a logarithmic function.(3)The cohesive strength increased first and then decreased with increasing moisture content.There existed a threshold moisture content that maximized the cohesive strength of the soils.Before reaching this threshold,the fine particle contents had a significant impact on the cohesive strength;however,after exceeding the threshold,soil moisture content became the dominant influencing factor.(4)Based on the experimental results,a binary model for soil cohesive strength with joint influence of moisture content and scale distribution parameters was proposed.This research can provide scientific basis for geophysical interpretation of soil scale distribution and determination of mechanical parameters for debris flow source soils.
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维普
