土工平面应变仪压力室的改进

发布时间：2018-02-24 05:13

本文关键词： 平面应变仪新型压力室土样与面板的摩擦数字图像测量　出处：《岩土力学》2017年05期 　论文类型：期刊论文

【摘要】：现有的平面应变试验仪都不能很好地解决接触摩擦的问题,试验中土样与约束面板之间存在较大的摩擦力影响变形测量的准确性。在总结平面应变仪发展历程的基础上,根据加载方式将平面应变仪分为4类,分析了现有的平面应变试验仪的特点和存在的问题;介绍了一种改进的平面应变仪的压力室。改进后的压力室在前、后约束面板与土样之间分别增设一层厚约3 mm的密封水膜。在试验过程中,包裹土样的橡皮膜与密封水膜的硅胶膜紧密贴合而不直接与面板贴合,可以消除土样与面板之间的摩擦。同时,新型的压力室还可应用于土样变形数字图像测量系统,实时测量土样表面的变形分布,可以比较精确地测量土样的表面变形、剪切带的形成过程及特征。分别使用改进的压力室和未改进的压力室对福建标准砂进行平面应变试验,前者测得的应力-应变关系曲线的峰值比后者低约60%。制备相同干密度的土样分别进行不同围压条件下的三轴试验和平面应变试验测取土样的抗剪强度,使用改进压力室得到的抗剪强度参数与三轴试验测得的结果很接近,而使用未改进的压力室测得结果则明显不合理。
[Abstract]:The problems of contact friction can not be solved very well by the existing plane strain test instruments. The accuracy of deformation measurement is affected by the friction between the soil sample and the restrained panel. Based on the summary of the development history of the plane strain gauge, According to the loading mode, the plane strain gauge is divided into four categories, the characteristics and existing problems of the existing plane strain tester are analyzed, and the pressure chamber of an improved plane strain gauge is introduced. A sealed water film of about 3 mm thick is added between the rear confined panel and the soil sample. During the test, the rubber film wrapped in the soil sample is tightly bonded with the silica gel film of the sealed water film, but not directly attached to the panel. At the same time, the new pressure chamber can be used in the digital image measuring system of soil sample deformation, which can measure the deformation distribution of soil sample surface in real time, and can measure the surface deformation of soil sample more accurately. The formation process and characteristics of shear zone. The plane strain tests of Fujian standard sand were carried out by using the improved pressure chamber and the unimproved pressure chamber, respectively. The peak value of stress-strain curve measured by the former is about 60% lower than that of the latter. Soil samples with the same dry density are prepared to conduct triaxial tests under different confining pressures and plane strain tests to measure the shear strength of soil samples. The shear strength parameters obtained by using the improved pressure chamber are very close to the results obtained by triaxial test, but the results obtained by using the unimproved pressure chamber are obviously unreasonable.
【作者单位】：大连理工大学工程力学系;大连理工大学工业装备结构分析国家重点实验室;
【基金】：国家自然科学基金项目(No.51309047)~~
【分类号】：TU415

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