均质软土地基上土堤稳定性的极限分析方法

为评估均质软土地基上土堤的稳定性,假设地基土体沿圆弧形滑动面破坏,不排水抗剪强度随深度线性增加,并假设土堤材料沿对数螺旋线形滑动面破坏,采用黏聚力和内摩擦角描述其抗剪强度,基于上限定理,建立了一种稳定性分析方法,用于计算得到土堤的无量纲化的稳定数和稳定图,并确定土堤的最小安全系数和临界滑动面。采用本文方法对土堤失稳现场试验工程案例开展了计算分析,结果表明,所得到的最小安全系数与土堤的实测失稳条件吻合,最小安全系数与临界滑动面的计算结果也与变分极限平衡法和条分极限平衡法所得到的计算结果吻合良好。

Limit analysis approach for stability of embankments on homogeneous soft soil

The stability analysis is performed for the embankments founded on the ground of a homogeneous soft soil. The soft soil is assumed to fail along an arc-shaped surface. The undrained shear strength of ground soil is considered to increase linearly with depth. The embankment material is assumed to fail along a log-spiral surface. The cohesion and internal friction angle parameters are adopted for describing the shear strength of embankment soil. An approach for the stability analysis is thus derived by using the upper-bound theorem. It can be used to calculate the non-dimensional stability numbers and stability charts for the determination of the minimum factor of safety and the critical slip surface of embankment. A case study is carried out by using the proposed approach. The calculated minimum factor of safety satisfies the measured failure condition. A good agreement is also obtained between the minimum factor of safety and the critical slip surface calculated using the proposed approach and those calculated using the slice approach and the variational approach of limit-equilibrium analysis.