考虑桩-土摩擦的双排桩桩间有限土体土压力计算

Calculation of Earth Pressure for Limited Soil of Double-row Piles in Consideration of the Pile-soil Friction

在双排桩支护结构中,前、后排桩之间的土体也被称之为有限土体。而建立在半无限土体假定的传统朗肯土压力理论并不适用于有限土体的计算。通过考虑前、后排桩与桩间有限土体之间的切向摩擦力作用,建立了双排桩桩间有限土体土压力计算模型,并在进行适当简化后给出了桩间有限土体土压力的表达式。通过与FLAC3D进行对比表明,给出的计算公式与数值模拟拟合较好,证明计算公式是合理的。同时揭示出桩间有限土体土压力强度在开挖面附近增大趋势逐渐降低;桩间有限土体土压力与朗肯主动土压力相比,深度越大,差别越大。在规范要求范围内研究有限土体宽度L时(2d^5d),土压力、桩身弯矩均随L增大而增大;桩身位移随L增大而减小。

The soil between the front-row pile and the back-row pile is called the limited soil in the structure of the double-row piles. Whereas based on the assumption of semi-infinite soil for the traditional Rankine soil pressure theory does not apply to the calculation of limited soil. In this paper, the interaction between the double-row piles and the limited soil is considered, the calculation formula of earth pressure for limited soil is established. The expression of the earth pressure intensity for limited soil is also given after appropriate simplification. It is shown that the formulas given in this paper fit well with the numerical simulation. It is proved reasonably comparing with the FLAC3D. The results show that the increasing trend of the soil pressure for limited soil is reduced gradually near the excavation surface. When the width of finite soil is valued from 2d to 5d in the range of specification, the soil pressure and bending moment of pile increases with the width, whereas the displacement of pile decreases with the width.