浸水路基边坡最小势能稳定性分析方法

An Analytical Method of Minimum Potential Energy Stability of Submerged Subgrade Slope

为丰富浸水路基边坡稳定性分析方法,针对任意形状的滑裂面,视滑体为一个刚体,不划分条块,分别计算浸润线上下的弹性压缩势能与剪切势能,并考虑动水压力对系统势能的影响,得到滑体系统的总势能;然后基于最小势能原理求得滑体虚位移,通过力与位移的关系求出滑裂面上的法向力和极限抗滑力,计算浸水路基边坡潜在滑动方向上抗滑力与下滑力的代数和之比得到安全系数,提出了动水压力作用下的浸水路基边坡最小势能稳定性分析方法,并开发了相应的浸水路基边坡稳定性分析程序。通过算例对比验证及参数影响分析,结果表明:路基边坡在浸水以后,安全系数减小,稳定性降低;在考虑滑裂面处的剪切势能以及动水压力的作用后,最小势能法的计算结果与极限平衡法的计算结果相差在5%以内,并且随着土体的黏聚力或内摩擦角变化,其安全系数的变化趋势与极限平衡法及工程实际相吻合;在临坡水位下降的过程中,路基边坡的安全系数先减小,并在临坡水位下降到1/2坡高附近时达到最小值,之后又有一定的增大。该方法无需划分条块,计算过程简单,不需要迭代,便于工程应用,对完善浸水路基稳定性分析理论及其应用具有重要的意义。

In order to enrich the analysis method of submerged subgrade slope stability,For any shape of the slip surface,the slide is treated as a rigid body without dividing the bars. The total potential energy of the slippage system is obtained by calculating the elastic compressive potentials and shear potentials above and below the infiltration line,and considering the influence of hydrodynamic pressure on the potential energy of the system. Then,the virtual displacement of the slip body is obtained by the principle of minimum potential energy. The normal force and ultimate slip resistance on the slip surface are obtained by the relationship between the force and the displacement. The safety factor is the ratio of the algebraic sum of the anti-slip and the sliding force in the potential sliding direction of the slope,the minimum potential stability analysis method of submerged subgrade slope under hydrodynamic pressure is proposed,and the corresponding program is developed. By case comparison and verification and parameter analysis,it is concluded that（ 1） The safety factor and the stability will decrease after the slope is submerged;（ 2） The calculation result from theminimum potential energy method differs from the calculation result of the limit equilibrium method by less than 5% considering the shear potential energy and hydrodynamic pressure at the slip surface. With the change of soil cohesion or angle of internal friction,the change trend of the safety factor is consistent with that from limit equilibrium method and engineering practice.（ 3） During the process of falling water level,the safety factor of the subgrade slope decreases first,and reaches the minimum when the water level drops to 1/2 slope height,then increases. The method does not need to divide the blocks,the calculation process is simple and unnecessary to iterate,and it is easy to apply in engineering. It is of great significance to perfect the submerged subgrade stability analysis theory and its application.