基于离散元的盾构开挖面合理支护压力

发布时间：2018-05-29 18:03

本文选题：盾构开挖面 + 支护压力比　；参考：《上海交通大学学报》2014年06期

【摘要】：采用离散元法(DEM)对无水砂土地层(摩擦角37°)3种埋深条件下盾构隧道开挖面的颗粒流动及渐进性破坏过程进行了模拟,分析研究了开挖面极限支护压力及周围地层扰动分布的变化规律,得到:①不同埋深条件下,开挖面极限支护压力均出现在开挖面位移为0.06D(D为隧道直径)时,对应支护压力比为10%~20%,砂土强度软化现象导致最终极限支护压力增大.②支护压力比降至40%~50%为剧烈地层扰动及显著地表变形的触发点.当开挖面支护压力比降低至40%~50%时,地层扰动范围和程度对隧道埋深非常敏感,如埋深由2D降低至0.5D时,扰动范围扩大了3倍,最大扰动程度提高了1倍;地表产生明显大幅沉降.③基于极限破坏的支护压力比为10%~20%,而基于变形控制的支护压力比为40%~50%,虽明显大于前者,但支护压力仅为静止土压力的40%~50%.综合考虑盾构刀盘磨损及地层支护效果,在无水砂土地层中采用支护压力比为40%~50%是一种合理选择.
[Abstract]:The particle flow and progressive failure process of excavated surface of shield tunnel are simulated by discrete element method (DEM) under the condition of dry sand soil layer (friction angle 37 掳). This paper analyzes and studies the variation law of the limit support pressure of excavating face and the distribution of strata disturbance around it. It is concluded that under the condition of different buried depth of 1: 1, the ultimate support pressure of excavating face appears when the displacement of excavated face is 0.06D(D as the diameter of tunnel). The corresponding support pressure ratio is 10 ~ 20. The ultimate support pressure increases by .2% and falls to 40% and 50% is the trigger point for severe ground disturbance and significant surface deformation. When the pressure ratio of excavation surface support is reduced to 40 ~ 50, the disturbance range and degree are very sensitive to the depth of the tunnel. If the depth of excavation is reduced from 2D to 0.5D, the range of disturbance is expanded by 3 times, and the maximum disturbance degree is increased by 1 times. The support pressure ratio based on limit damage is 10 / 20, while the support pressure ratio based on deformation control is 40 / 50, which is obviously larger than that of the former, but the support pressure is only 40 / 50 of the static earth pressure. Considering the wear of shield cutter head and the effect of formation support, it is a reasonable choice to apply the support pressure ratio of 40% to 50% in the impervious sandy soil.
【作者单位】：同济大学地下建筑与工程系;同济大学岩土及地下工程教育部重点实验室;
【基金】：国家自然科学基金项目(51078292,51378389)
【分类号】：U455.43

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