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通过对不同干密度及含水量的重塑黄土进行室内抗拉强度试验,探究轴向压裂法致使试样破坏的机理及一般规律。结果表明,黄土的抗拉变形破坏可分为4种类型:I类,高干密度低含水量(干密度大于1.65 g·cm~(-3),含水量小于15%),抗拉强度介于8~12 k Pa;Ⅱ类,低干密度低含水量(干密度小于1.60 g·cm~(-3),含水量小于15%),抗拉强度介于4~8 k Pa;Ⅲ类,高干密度高含水量(干密度大于1.65 g·cm~(-3),含水量大于17%),抗拉强度介于4~8 k Pa;IV类,低干密度高含水量(干密度小于1.60 g·cm~(-3),含水量大于17%),抗拉强度介于3~4 k Pa。I类、Ⅱ类破坏类型属于脆性破坏,Ⅲ类、IV类属于塑性破坏。重塑黄土抵抗变形最弱的含水量为15%。通过对比分析黄土、普通黄黏土、红黏土及膨胀土的抗拉强度发现,在最优含水量处,不同干密度下黄土的抗拉强度均最小。黏性土的持水能力远超过黄土。黏土及膨胀土的抗拉强度均在最优含水量处达到最大值,而黄土的抗拉强度随着含水量的增加持续减小。研究结果对黄土强度特性的理解具有一定的参考意义。
The indoor tensile strength test of remolded loess with different dry density and water content is carried out to investigate the mechanism and general rule of the failure caused by the axial fracturing method. The results show that the tensile deformation and failure of loess can be divided into four types: Class I, high dry density, low water content (dry density> 1.65 g · cm -3, moisture content less than 15%), tensile strength At 8 ~ 12 kPa; Class Ⅱ, low dry density and low water content (dry density less than 1.60 g · cm -3, moisture content less than 15%), tensile strength between 4 ~ 8 k Pa; , High dry density and high water content (dry density of more than 1.65 g · cm -3, moisture content of more than 17%), tensile strength between 4 ~ 8 kPa; Class IV, low dry density and high water content The density is less than 1.60 g · cm -3, the water content is more than 17%) and the tensile strength is between 3 and 4 kPa. Class I, Class II damage types are brittle failure, Class III, IV are plastic damage. Remodeled loess resists the weakest water content of 15%. By comparing and analyzing the tensile strength of loess, ordinary yellow clay, red clay and expansive soil, it is found that the tensile strength of loess at the optimal water content and dry density is the smallest. Cohesive soil water capacity far more than loess. The tensile strength of clay and expansive soil reach the maximum at the optimal water content, while the tensile strength of loess decreases with the increase of water content. The research results have some reference significance for the understanding of loess strength characteristics.