上软下硬岩质地层浅埋大跨隧道松动压力计算

发布时间：2018-08-04 19:04

【摘要】：针对现有方法在上软下硬岩质地层中浅埋大跨隧道松动压力计算方面存在的问题,通过离散元数值模拟和正交试验,分析了围岩的松动破坏机制、风化层厚度和岩体中节理分布状态对隧道松动区形状和范围的影响规律及敏感性。结果表明:影响松动区的主要因素依次为风化层厚度、隧道埋深、贯通倾斜节理的倾角和间距、风化层水平节理间距;松动区可分为拱形和塌穿形两种类型,其边界曲线分别可用抛物线和乘幂函数近似表示。针对塌穿形松动区,通过回归分析建立了地表松动宽度和拱顶松动土条水平长度的计算公式。按照应力传递原理,在松动区内以梯形微分岩土条为对象,通过分层积分,推导出可反映节理产状和风化层厚度影响的浅埋大跨隧道围岩松动压力计算公式。工程实例计算表明,与现有方法相比,所提方法计算的松动压力值最小。
[Abstract]:In view of the problems existing in the existing methods in the calculation of loosening pressure of shallow large-span tunnels in the upper soft and hard rock layers, the mechanism of loosening and failure of surrounding rock is analyzed by numerical simulation and orthogonal test of discrete element. The influence of the thickness of weathered layer and the distribution of joints in rock mass on the shape and range of loose zone of tunnel and its sensitivity. The results show that the main factors influencing the loosening zone are the thickness of weathering layer, the depth of tunnel, the inclination angle and spacing of inclined joint, the horizontal joint spacing of weathered layer, and the loosening zone can be divided into two types: arch and collapse. The boundary curve can be expressed by parabola and power function respectively. In this paper, the formulas of the loosening width of the surface and the horizontal length of the loose soil strip on the arch roof are established by regression analysis. According to the principle of stress transfer, taking the trapezoid differential rock and soil strip in the loose zone as the object, the formula for calculating the loosening pressure of the surrounding rock of the shallow buried large-span tunnel can be deduced by stratified integration, which can reflect the influence of the occurrence of joints and the thickness of weathered layer. The engineering example shows that compared with the existing methods, the loosening pressure calculated by the proposed method is the smallest.
【作者单位】：北京交通大学土木建筑工程学院;中铁隧道勘测设计院有限公司;
【基金】：中央高校基本科研业务费专项经费(No.2012YJS091)
【分类号】：U451

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