膨胀土原位孔内剪切试验与强度响应特征

发布时间：2018-05-18 04:34

本文选题：孔内剪切试验 + 膨胀土　；参考：《岩土力学》2017年02期

【摘要】：针对膨胀土堑坡防护工程中不同的施工工序和降水入渗诱发灾害频发现象,基于原位孔内剪切试验,通过施加不同法向应力水平,以及成孔后注水浸泡等工况下的现场剪切试验,获得南阳某堑坡膨胀土强度特性随荷载施加方式与浸水条件的变化规律。结果表明:膨胀土孔内剪切试验所得的剪应力-剪切位移曲线总体上呈现弱硬化变形特征;浸水对抗剪强度影响很大,最大降幅达56.9%,主要表现为黏聚力的降低,最大值达18.1 k Pa。预加载荷对浸水软化效应具有一定抑制作用,但当预加载荷超过某一应力水平时,难以发挥更大的抑制效果。黏聚力与预加载荷呈线性正相关;内摩擦角与预加载荷呈线性负相关,但降幅甚微。在实际工程中,膨胀土边坡稳定性分析应考虑降雨入渗对强度参数的影响,同时充分利用抗剪强度参数和预加载荷的线性关系,可根据工程要求达到的安全系数反推出所需的预加载荷大小,从而指导实际工程施工。该研究可为膨胀土工程场地评价、参数选取与灾害评价提供技术依据和参考。
[Abstract]:In view of different construction procedures and frequent disasters induced by precipitation infiltration in expansive soil slope protection engineering, based on in-situ shear test in hole, different normal stress levels are applied. The field shear tests were carried out under the conditions of water flooding and soaking after drilling. The variation of strength characteristics of expansive soil on a cutting slope in Nanyang was obtained with load applying mode and soaking condition. The results show that the shear stress-shear displacement curve obtained from the in-hole shear test of expansive soil shows the characteristics of weak hardening deformation in general, and the immersion shear strength has a great influence on the shear strength, with the maximum decrease of 56.9%, which mainly shows the decrease of cohesive force, the maximum value being 18.1 k Pa. Pre-loading has a certain inhibitory effect on the soaking softening effect, but it is difficult to exert a greater inhibition effect when the pre-loading exceeds a certain stress level. The cohesive force is linearly positively correlated with the preload, and the angle of internal friction is linearly negatively correlated with the preloading, but the decrease is small. In practical engineering, the influence of rainfall infiltration on strength parameters should be taken into account in the stability analysis of expansive soil slope, and the linear relationship between shear strength parameters and preload should be fully utilized. According to the safety factor required by the project, the size of preload can be deduced and the actual construction can be guided. The research can provide technical basis and reference for engineering site evaluation, parameter selection and disaster evaluation of expansive soil.
【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;中国科学院大学;
【基金】：国家自然科学基金重点项目(No.41430634) supported by the Key Program of National Nature Science Foundation of China(41430634)
【分类号】：TU443

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