关岭组一段泥岩全风化层剪切力学试验研究

Experimental Research on the Shear Mechanical Properties of Mudstone Weathering Layer in the First Paragraph of Guanling Group

研究目的:三叠系中统关岭组第一段(T2g^1)泥岩全风化层富水后易发生软化,导致剪切力学性能降低。为研究泥岩全风化富水后的力学性能,本文以三叠系中统关岭组第一段(T2g^1)泥岩全风化层为研究对象,通过室内试验建立天然含水率及天然孔隙比与力学指标之间的关系。研究结论:(1)随天然含水率的增大,内摩擦角降低,且呈二次多项式关系;(2)天然孔隙比越小,随天然含水率增大,内摩擦角降低的幅度增大;(3)随天然含水率的增大,凝聚力呈线性降低;天然孔隙比越小,随天然含水率增大,凝聚力降低的幅度变大;(4)当天然含水率为40%~65%时,随天然含水率的增大,内摩擦角降低,且天然含水率越小,随天然孔隙比增大,凝聚力降低的幅度增大;(5)当天然含水率大于65%时,随天然孔隙比增大,内摩擦角呈先增大后减小二次多项式函数变化关系;(6)随天然孔隙比的增大,凝聚力呈线性降低;(7)当天然含水率为50%~55%时,随天然含水率增大,凝聚力降低的幅度较大;(8)本研究成果可为类似地层工程地质问题处理提供参考。

Research purposes:The mudstone weathering layer in the first paragraph of the middle Triassic Guanling group(T2g1)is prone to soften after rich water,resulting in degradation of shear mechanical performance.In order to study the mechanical properties of mudstone after full weathering and rich water,the paper took the first paragraph of the middle Triassic Guanling group(T2g1)as the research object,and established the natural moisture content and the relationship between the natural void ratio and mechanical index by laboratory test.Research conclusions:(1)The internal friction angle decreased with the increase of natural moisture content,and the relations of quadratic polynomials were obtained.(2)The smaller the natural void ratio,the lower the internal friction angle with the increase of natural moisture content.(3)The cohesion decreases linearly with the increase of natural moisture content.The smaller the natural void ratio,the greater the degree of cohesion decrease with the increase of natural moisture content.(4)When the natural moisture content is 40%~65%,with the increase of natural moisture content,the internal friction angle decreases,and the natural moisture content is smaller,with the increase of natural pore ratio and the decrease of cohesion.(5)When the natural moisture content is greater than 65%,with the natural void ratio increasing,the internal friction angle increases first and then reduces which shows the change relation of quadratic polynomial function.(6)With the increase of natural void ratio,the cohesion is linearly decreasing.(7)When the natural moisture content is 50%~55%,the cohesion decreases with the increase of natural moisture content.(8)The research results can provide reference for similar engineering geological problems.