复杂条件下深基坑多层支护方法及数值模拟研究

海相沉积土岩复合地层，其上部淤泥质土承载力低易变形，合理选择支护方式对此条件下深基坑工程的稳定性显得尤为重要。而对于建筑物密集的区域，施工场地狭小，满足不了台阶式支护等对施工场地的要求，因此该文针对此种复杂地质条件，提出了多层支护结构的深基坑支护方式及其数值分析方法。运用有限差分软件FLAC^3D实现了多层支护结构的数值模拟，分析了采用不同支护结构时深基坑围护桩桩体挠曲位移、桩顶水平位移和竖向位移的变化规律。结合现场试验、监测数据研究了深基坑多层支护结构的变形特性和支护作用。与传统深基坑支护形式对比，多层支护结构能减少20%的锚索用量（密度上），优化了支护方式。研究成果对海相沉积土岩复合地层条件下的深基坑工程具有重要的理论和工程指导意义。

MULTI-LAYER SUPPORTING METHOD AND NUMERRICAL SIMULATION FOR DEEP FOUNDATION PIT UNDER COMPLEX CONDITION

The composite strata of coastal regions are composed of soil and rock, and the upper mucky soil has low bearing capacity. Under this condition, it is significantly important to choose suitable supporting mode to ensure the stability of deep foundation pit. However, the stepped supporting is not allowed because of the narrow construction site. The multi-layer supporting structure of deep foundation pit is proposed and numerical analysis is carried out. The finite difference software FLAC3D is used to analyze the deflection and the pile-top horizontal and vertical displacement of retaining structure. Combined with site test and monitoring data, the deformation characteristics and support effects of the multi-layer supporting structure are investigated. Compared with the conventional supporting structure, the dosage of anchor cable (in the density) is reduced by 20% through adopting the multi-layer supporting structure, and the support system is optimized. The research results provide meaningful theoretical and practical guide for deep foundation pit in composite strata of coastal regions.