干湿循环效应下黄土抗拉强度试验研究

Experimental studies of tensile strength of loess in drying-wetting cycle

采用单轴拉伸法对原状和重塑黄土干湿循环下的抗拉强度进行试验研究,通过试验数据探讨原状和重塑黄土的抗拉强度与含水率和干湿循环次数的关系,分析干湿循环下黄土的抗拉强度衰减机制。试验结果表明:原状和重塑黄土的抗拉强度随含水率的减小呈非线性的增大,为负指数函数关系;同一含水率下的原状和重塑黄土的抗拉强度随干湿循环次数的增加而减小,最后基本趋于稳定。多次的干湿循环后原状黄土的抗拉强度衰减值与重塑黄土的抗拉强度衰减值和黄土抗拉结构强度之和基本相等,证明多次的干湿循环作用打破了原状黄土的原有结构,使得其抗拉结构强度消失;间接说明经过多次干湿循环后原状和重塑黄土的吸附强度衰减值相同,并使得原状和重塑黄土具有基本相同的结构。

Uniaxial tensile method test is used to obtain tensile strength of undisturbed and remolded loess by dry-wet circulation experiment. The relationship among the tensile strength, water content and dry-wet circle number is discussed. The attenuation mechanism of tensile strength of loess is analyzed. It is shown that tensile strength of loess nonlinear increases with decreasing water content. Tensile strength of undisturbed and remolded loess decreases with increasing number of cycles and finally reaches to a constant state. The sum of tensile attenuation value and tensile structural strength is equal to tensile attenuation value of undisturbed loess. It is proved that the original structure of undisturbed loess is broken by many times of dry-wet cycles, and its tensile structural will disappear. The dry-wet cycle is not only makes the same as the adsorption strength of undisturbed and remolded loess, but also makes the soil to be a stable and reliable equilibrium, and has the same structure of soil mass.