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为研究EPS板的卸载效果及机制,通过室内模型试验,探讨了不同密度、厚度EPS板卸载的沟槽式高填黄土明洞垂直土压力、土体位移变化规律。结果表明:在明洞顶一定高度范围内铺设EPS板可改变土体的相对沉降方向,引起土体应力重分布,促使土拱效应的形成,从而减小明洞洞顶垂直土压力;EPS板密度越小,厚度越大,对明洞洞顶垂直土压力的卸载越明显。同时,铺设EPS板使明洞洞顶同一平面垂直土压力分布随距明洞中轴线距离的增大呈减小→增大→减小的趋势,在0.7和1.3倍明洞宽度处出现转折点。最后,通过数值模拟和模型试验的对比,验证了试验结果的准确性,以及数值模拟所选参数的合理性,并进一步形象描绘了土拱效应的应力集中形态,揭示了EPS板的卸载机制。研究成果可为沟槽式高填黄土明洞EPS板卸载措施的设计和施工提供参考。
In order to study the unloading effect and mechanism of EPS slab, the vertical earth pressure and displacement of vertical soil in gully high fill loess with different density and thickness unloading of EPS plate were discussed through indoor model test. The results show that laying EPS board within a certain height of the top of the Ming dynasty can change the relative subsidence direction of soil so as to cause the stress redistribution and promote the formation of soil arching, so as to reduce the vertical earth pressure at the top of Myeong- The smaller the density and the larger the thickness, the more obvious the unloading of the vertical earth pressure on the top of Myeong-dong. At the same time, EPS boards were laid so that the vertical earth pressure distribution on the same plane of the top of the hole in Myeongdong decreased, then increased and then decreased with the increase of the distance from the center axis of Myeong-dong, turning point appeared at the width of Myeong-dong of 0.7 and 1.3 times. Finally, the accuracy of the test results and the rationality of numerical simulation of the selected parameters are verified by comparison between numerical simulation and model test. The stress concentration form of soil arching effect is further vividly illustrated, and the unloading mechanism of EPS plate is revealed. The research results can provide a reference for the design and construction of the EPS plate unloading measures for the bright-fill loess in Gyeongsang-do.