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为研究不同卸载措施下沟槽式高填黄土明洞垂直土压力、土体沉降变化规律,通过室内模型试验,对不同方案下的卸载效果进行对比分析。结果表明:增大填土边坡坡角、明洞顶设置低压实土、铺设土工格栅、提高明洞两侧填料压缩模量可减小明洞洞顶土压力,其中,增大边坡坡角卸载作用最优。与无边坡相比,明洞洞顶垂直土压力卸载率可达20.6%,若与低压实土形成的土拱效应及土工格栅的“提兜效应”相结合,有利于进一步减小明洞洞顶垂直土压力。同时,填土高度较低时,垂直土压力接近均匀分布;随着填土高度的增大,垂直土压力分布曲线随距明洞中轴线距离的增加呈先减小后稳定的趋势;低压实土的设置使明洞顶虚实土接触附近垂直土压力分布曲线出现突变。研究成果可为沟槽式高填黄土明洞卸载措施的设计和施工提供参考依据。
In order to study the variation law of vertical earth pressure and soil subsidence under different unloading measures in the tunnel with high filling loess of trench type, through the indoor model test, the unloading effect under different schemes was compared and analyzed. The results show that increasing the slope angle of fill slope, setting low pressure solid soil at the top of Ming dynasty, laying geogrid, and increasing compressive modulus of fillings on both sides of Myeong-dong can reduce the top soil pressure of Mingdong cave. Slope slope angle unloading role of the best. Compared with no slope, the vertical earth pressure on the top of Myeong-dong can achieve an unloading rate of 20.6%. If combined with the soil arching formed by low-pressure solid earth and geotextile’s “back pocket effect”, this will be further reduced Xiaoming hole vertical earth pressure. At the same time, the vertical earth pressure is close to uniform distribution when the fill height is low. With the increase of fill height, the vertical earth pressure distribution curve first decreases and then stabilizes with the increase of the distance from the central axis of the Myeongdong. The setting of real soil causes the sudden change of vertical earth pressure distribution curve near the contact of the top virtual soil and the bare soil in Myongdong. The research results can provide references for the design and construction of the unloading measures of the tunnel with high filling loess in trenches.