从变形、水量变化和强度三方面验证非饱和土的两个应力状态变量

发布时间：2018-01-15 07:15

本文关键词：从变形、水量变化和强度三方面验证非饱和土的两个应力状态变量　出处：《岩土工程学报》2017年05期 　论文类型：期刊论文

【摘要】：为了验证非饱和土两个应力状态变量的合理性,对常规非饱和土三轴仪进行了改进,采用3个压力体积控制器分别控制孔隙水压力、内室压力和外室压力,提高了量测体变和含水率的精度;用加荷器施加轴向荷载,可以方便地控制偏应力。在笔者前期用各向等压试验验证非饱和土的两个应力状态变量的基础上,使用改进的非饱和土三轴仪和重塑Q_3黄土做了两类验证试验:第一类是两组控制净围压、偏应力和吸力的固结不排水剪切试验,第二类是3组控制净围压和吸力的固结排水剪切试验。在第一类试验中,等值改变(增加或减少)总围压、孔隙水压力和孔隙气压力而保持净围压、吸力和偏应力本身不发生变化,发现试验过程中土样的体积变化和含水率变化均非常小,可以忽略不计。第二类试验的每一组包含两个控制净围压和吸力分别相同的固结排水剪切试验,其中一个试样在固结完成后直接进行排水剪切试验,另一个试样在固结完成后等值增加总围压、孔隙水压力和孔隙气压力而保持净围压和吸力本身不发生变化的条件下进行排水剪切试验,发现二者的抗剪强度、剪切过程中的体积变化、排水量和广义剪应变都分别十分接近,可以认为两两相等。研究结果从变形(包括体应变和剪应变)、水量变化和强度3个方面说明描述非饱和土的两个应力状态变量是合理的,进一步夯实了非饱和土力学的应力理论基础,为非饱和土的两个应力状态变量理论提供了牢靠的试验依据。
[Abstract]:In order to verify the rationality of two stress state variables of unsaturated soil, the conventional unsaturated soil triaxial instrument was improved. Three pressure volume controllers were used to control pore water pressure, inner chamber pressure and external chamber pressure respectively. The accuracy of measurement body variation and moisture content is improved. The stress of the unsaturated soil can be easily controlled by the axial load applied by the loader, and the two stress state variables of the unsaturated soil are verified by the author's tests in each direction in the early stage. Two kinds of tests were carried out using the improved unsaturated soil triaxial apparatus and remolded QS3 loess. The first one was two groups of undrained shear tests which controlled the net confining pressure, deviated stress and suction. In the first type, the net confining pressure, pore water pressure and pore gas pressure are changed (increased or decreased), and the net confining pressure is maintained by changing (increasing or decreasing) the total confining pressure, pore water pressure and pore gas pressure. The suction and deflection stress itself do not change. It is found that the volume change and moisture content change of soil sample are very small during the test. Negligible. Each group of type II tests consists of two consolidation shear tests with the same net confining pressure and suction respectively, one of which is carried out directly after consolidation is completed. On the other hand, under the condition that the total confining pressure, pore water pressure and pore gas pressure are increased after consolidation, and the net confining pressure and suction itself remain unchanged, the shear strength of the two specimens is found. The volume variation, displacement and generalized shear strain are very close to each other in the shear process, which can be considered as equal. The results are derived from the deformation (including bulk strain and shear strain). It is reasonable to describe two stress state variables of unsaturated soil in terms of water quantity variation and strength, which further solidifies the stress theory foundation of unsaturated soil mechanics. It provides a reliable experimental basis for the theory of two stress state variables in unsaturated soils.
【作者单位】：兰州理工大学土木工程学院;机械工业勘察设计研究院;中国人民解放军后勤工程学院;延安大学建筑工程学院;空军工程大学机场建筑工程系;
【基金】：国家自然科学基金项目(11272353,11672330,51309199,51509257)
【分类号】：TU411
【正文快照】： 究院,陕西西安710043;4.延安大学建筑工程学院,陕西延安716000;5.空军工程大学机场建筑工程系,陕西西安710038)deviator stress,it is found that the volume change and moisturechange are very small and can be neglected.In the second typeof tests,each group contains

【相似文献】