软土地基刚/柔性组合墙面加筋土挡墙

Coupling DiscontinuousContinuous Simulation of Reinforced Soil Walls with Flexible/Rigid Facings on Soft Foundation

摘要:

基于软土地基直立刚/柔性组合墙面加筋土挡墙离心模型试验，建立离散连续耦合数值模型，采用离散单元颗粒流程序PFC和有限差分程序FLAC分别模拟加筋土挡墙和软土地基，研究软土地基上刚/柔性组合墙面加筋土挡墙的性状及内、外部稳定性.研究结果表明，数值模拟的挡墙沉降、墙面水平位移、墙底竖向土压力及墙面弯矩与离心模型试验结果吻合较好；挡墙在自重及上覆荷载作用下产生显著的沉降和不均匀沉降，但挡墙整体仍保持稳定，显示该型挡墙具有很好的适应软土地基大变形的能力；自重及上覆荷载作用使得连接件末端位置产生应力集中，导致此处的地基表面沉降最大；上覆荷载作用下，刚性墙面弯矩在墙中处最大，为外侧受拉，而在靠近墙底和墙顶处较小，为内侧受拉；软土地基上该型挡墙稳定性一般为深层滑移外部稳定性，其破坏面由过挡墙底层筋材后缘填土中的朗肯破坏面和地基中的圆弧滑移面组成；该型挡墙内部稳定性表现为随软土地基滑移破坏，挡墙内筋材由下至上依次断裂，形成过底层连接件后缘的朗肯破坏面.

Abstract:

A discontinuous and continuous coupling numerical model was established for a reinforced soil walls with flexible/rigid facings on soft soil based on centrifuge modelling. In the numerical model, the wall and soft foundation were simulated using particle flow code (PFC) and fast lagrangian code (FLAC), respectively. The behavior as well as the internal and external stability of the wall was investigated. The results show that the numerical results such as the settlement of retaining wall, the horizontal displacement of wall facing, the vertical earth pressure at wall base, and the moment of rigid wall facing are in good agreement with the measured results in the centrifuge modelling. The wall suffers a large and differential settlement due to its own weight and the surcharge loading, but the overall structure is still stable, indicating that the reinforced wall with flexible/rigid facings can well adapt to the soft foundation. The stress concentration is observed at the end of the anchor at selfweight loading and surcharge loading, leading to the maximum settlement in the foundation. At surcharge loading, the rigid wall at the middle bears a tensile force outside the wall and the maximum bending moment, whereas the rigid wall near the bottom and the top bears a tensile force inside the wall and the comparatively low bending moment. The reinforced wall with flexible/rigid facings on soft foundation generally suffers from the external stability of the deepseated failure. The failure surface is composed of the Rankine failure surface in the unreinforced soil and a circular failure surface in the soft foundation. The internal stability of the walls with flexible/rigid facings indicates that the reinforcements are fractured from the bottom to the top of the wall in sequence following the slip failure of soft foundation, forming a Rankine’s failure surface along the end of the anchors.