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为揭示荷载施加快慢对土体变形与强度特性的影响规律,基于三轴CU试验,开展了不同围压和含水率状态下,原状和重塑黄土加载速率效应的试验研究。在试验结果基础上,分析了加载速率对黄土应力-应变曲线特征、抗剪强度以及结构强度等的影响规律。研究结果表明:加载速率对黄土的应力-应变曲线形态有显著影响,高加载速率、低围压、低含水率可以导致应变软化现象的产生;加载速率对剪切强度的影响存在临界值,加载速率小于此值时抗剪强度随着加载速率的增大而增大,超过此值时抗剪强度又有一定程度的降低,呈现先增后减的特征;加载速率对抗剪强度参数c和φ的影响规律不尽相同:黏聚力c随着加载速率的增大呈现先增大后减小的规律,而内摩擦角φ则随着加载速率的增大单调递减;加载速率对黄土结构强度的影响规律与抗剪强度基本一致,亦存在一临界加载速率,结构强度随着加载速率的增大也表现出先增大后减小的规律。
Based on the triaxial CU test, the effects of different confining pressures and water cut rates on the loading rate effects of undisturbed and remolded loess were studied in order to reveal the influence of loading speed on the deformation and strength characteristics of soils. Based on the experimental results, the influence of loading rate on the characteristics of stress-strain curve, shear strength and structural strength of loess was analyzed. The results show that the loading rate has a significant effect on the stress-strain curve of loess. High loading rate, low confining pressure and low water content can lead to strain softening phenomenon. The influence of loading rate on shear strength has a critical value. When the rate is lower than this value, the shear strength increases with the increase of the loading rate, and the shear strength of the shear strength decreases to a certain extent when the rate is higher than the value. The influence law of φ is different: the cohesion c increases first and then decreases with the increase of the loading rate, while the internal friction angle φ decreases monotonically with the increase of the loading rate. The loading rate affects the loess structure The influence law of strength is basically consistent with the shear strength, and there is also a critical loading rate. The structural strength also shows the law of first increasing and then decreasing with the increase of loading rate.