重塑黏土抗拉强度试验研究与验证

Experimental study and verification on tensile strength of remolded clay

黏土的抗拉强度是决定土质边坡稳定的重要因素之一。由于土体的碎散性,使得黏土抗拉强度的研究一直进展较为缓慢。基于自行设计研发的直接拉伸试验装置对重塑黏土进行单轴拉伸试验,开展含水率和拉伸速率对重塑黏土抗拉强度影响规律的研究,并使用离散元方法对试验结果进行了验证。试验结果表明:(1)当拉伸速率等其他条件不变时,随着含水率的增加,重塑黏土的抗拉强度呈现出先增大再减小的趋势,峰值抗拉强度出现在最优含水率附近;(2)当含水率等其他条件不变时,随着拉伸速率的增加,重塑黏土的抗拉强度逐渐增大;(3)在试验含水率范围(18%~24%)内,重塑黏土在试验过程中发生塑性变形,并在达到峰值拉伸强度后表现出软化的破坏规律;(4)使用离散元模拟方法对上述试验得到的结果进行对比分析,重塑黏土的抗拉强度变化与试验结果一致,验证了本文方法的正确性。研究成果可用于土质边坡的稳定性分析以及边坡防护的计算和设计。

The tensile strength of clay is an important factor in determining the stability of soil slope.Due to the fragmentation of soil,the understanding of the tensile strength of clay is not clear.In this study,the uniaxial tensile test of remolded clay is carried out to analyze the influence of water content and tensile rate on the tensile strength of remolded clay based on the self-designed direct tensile test device.The test results show that:(1)The tensile strength of remolded clay increases first and then decreases with the increase of water content,as the other conditions(such as tensile rate)remain stable.The peak tensile strength occurs near the optimal water content.(2)The tensile strength of remolded clay increases with the increase of tensile rate,as other conditions such as water content remain unchanged.(3)In the water content range(18%-24%)of this study,the remolded clay undergoes plastic deformation under uniaxial tension,and shows softening failure law after reaching the peak tensile strength.(4)The discrete element simulation method is used to analyze and verify the results obtained from the above experiments.The results of this study can be used for the stability analysis of soil slope and the calculation and design of slope protection.