散粒材料压缩模量修正及群桩基础稳定性研究

Research of constitutive relation of granular material and stability of pile group foundation

天然沉积土在上覆土层重力作用下完成固结,其压缩模量大小和土层所受的前期固结压力大小直接相关。首先,分析岩土材料本构关系的主要影响因素,建立考虑模量随深度和体积应变变化的本构关系式;其次,建立桩基础稳定性问题的有限元求解格式,考虑水平荷载和下游冲刷深度对多种工况进行数值模拟分析;最后,根据计算结果,分析下游冲刷和水平荷载作用形成不对称接触边界对不同平面位置基桩受力特点,分析应力集中产生的原因及折屈失稳和整体稳定性问题。研究结果可为复杂大型工程群桩基础设计考虑桩、土及承台共同协调作用提供定量计算方法。

For sedimentary soil which completes the consolidation due to the gravity of the overburden, the value of its modulus is directly related to the value of pre-consolidation pressure. The main factors of constitutive relation for geotechnical material are first analyzed, considering its changes with depth and volumetric strain. Secondly, pile foundation stability problem＇s solving format is established for the finite element calculation, considering horizontal load and downstream scouting. Finally, based on the analytical results of the downstream erosion and contact force of different-plane-position pile due to asymmetric horizontal loads, the stress concentration and flexion instability and overall stability are analyzed for group pile foundation in large and complex engineering, considering synergism in the system of piles and soil and pile cap, so as to provide a method for quantitative calculation.