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传统的强度折减法采用相同的折减系数对黏聚力和内摩擦角进行折减,边坡达到临界状态时的折减系数就是边坡的安全系数,此单一折减系数的折减方法被定义为等比例折减。对于一个边坡几何构型和岩体重度确定的边坡而言,使边坡处于临界状态的黏聚力和摩擦系数组合并不惟一,等比例强度折减法所得到边坡临界状态的黏聚力和摩擦系数只是其中可能的一种潜在组合,因此,其只是众多寻找临界状态方法中的一种折减形式,并不一定就是最优的折减方式。基于以上认识,首先建立不同边坡形状、不同岩体重度条件下临界状态边坡的c-tanφ曲线,假设岩体的黏聚力和内摩擦角在衰减破坏的过程中应沿着距离c-tanφ临界曲线最短的路径折减,进而建立黏聚力和内摩擦角的配套折减原则,提出了一种双参数强度折减法。最后,通过3个算例比较了等比例强度折减法与双参数强度折减法的差异,结果表明,等比例强度折减法和双参数强度折减法得到的边坡临界状态并不相同,后者得到的临界滑动面范围要比前者得到的滑动面范围大。
The traditional strength reduction method uses the same reduction factor to reduce the cohesion and internal friction angle. When the slope reaches the critical state, the reduction factor is the safety factor of the slope. The reduction method of this single reduction factor is used Defined as an equal reduction. For a slope with a geometrical configuration of slope and severe rock mass, the combination of cohesion and friction coefficient that makes the slope critical is not unique, and the cohesion of the slope obtained by the equivalent strength reduction method Force and friction coefficient are only one of the potential combinations among them. Therefore, it is only one of the many reductions in finding critical states and may not be the optimal one. Based on the above understanding, we first establish the c-tanφ curve of the slope with different slope shapes and critical rock mass under different rock mass severity. Suppose the cohesion and internal friction angle of rock mass should be along the distance c- tanφ the shortest path of the critical curve to reduce, and then establish cohesion and internal friction angle supporting reduction principle, proposed a two-parameter strength reduction method. Finally, the difference between equal-intensity reduction method and double-parameter strength reduction method is compared by three examples. The results show that the critical state of slope obtained by equal-strength reduction method and double-parameter strength reduction method is not the same, The critical slip surface range is larger than the former slip surface range.