压实粘土单轴拉伸变形特性试验研究

为了研究土体的拉伸变形特性,进而更好地去分析与解决土体由于拉伸破坏而引起的裂缝与地表塌陷等工程问题,本文以压实粘土为研究对象,基于自主研发的新型土工单轴拉伸试验装置开展了系统的试验研究,探讨了压实粘土的破坏形式与影响因素,以及峰值位移随试验变量的变化规律与拟合公式。研究结果表明：压实粘土单轴拉伸破坏形式不固定,包括拉伸断裂面形状不固定；断裂面为试样薄弱面,断裂面唯一,但薄弱面不一定唯一；断裂面的位置受试样尺寸与拉伸速率影响；拉伸破坏不是纯脆性破坏,而是存在软化阶段。另外,压实粘土的峰值位移受试验条件的影响明显,具体表现在：峰值位移随拉伸段长度的增加而增大,二者呈现出较好的对数关系；峰值位移随拉伸速率的增加而增大,二者呈现出较好的线性关系；峰值位移随压实度的增加而增大,二者表现出较好的线性关系；峰值位移随含水率的增加而增大,二者表现出较好的线性关系。

Experimental study on uniaxial tensile deformation characteristics of compacted clay

In order to study the tensile deformation characteristics of soil, and then better to analyze and solve the engineering problems of cracks and surface subsidence caused by the tensile failure of soil. In this paper, the experimental research about compacted clay was carried out based on the independently developed uniaxial tensile test device, and the failure modes and factors of compacted clay, also with the variation and fitting formula of peak displacement were discussed. The results show that the failure mode of compacted clay is not fixed, including the shape of tensile fracture surface is not fixed, the fracture surface is the weak surface of specimen, and the fracture is unique but the weak surface is not always unique, the position of fracture surface is impacted by the specimen size and stretching rate, failure mode is not pure brittle failure, but there is a softening phrase. In addition, the peak displacement of compacted soil is significantly affected by the test conditions, the specific features include the following aspects: with the increase of the length of stretching section, the peak displacement increases logarithmically; with the increase of the stretching rate, the peak displacement increases linearly; with the increase of compactness, the peak displacement increases linearly; with the increase of moisture content, the peak displacement increases linearly.