深回填对拉板桩结构受力性能研究

Mechanical behavior of deep backfill opposite-pull sheet pile structure

深回填对拉板桩结构在建造方式、工作机理等方面与常规板桩结构有较大区别。基于某板桩码头工程实例,通过理论分析和数值手段对其受力性能和计算方法进行研究。提出施工期锚碇结构前有限梯形回填区被动土压力理论计算公式,为土弹簧刚度折减提供量化依据。分析该类型板桩结构在使用期的剪切破坏模式,推导出回填体极限抗剪承载力计算公式。提出基于施工流程的杆系元简化计算方法,并进行不同分析手段对比;发现在不考虑施工期初始可控位移值的情况下,杆系元简化方法、三维结构-土整体有限元方法得到的施工期位移增量值为55 mm和43mm,另外使用期位移值分别为15 mm、16 mm,结果接近,验证了简化计算方法的合理性。

There are significant differences between the deep backfill opposite-pull sheet pile structure and the conventional structure in construction mode and working mechanism.Based on an engineering example of sheet piled wharf,the mechanical behavior and calculation method of the type of sheet pile structure were studied theoretically and numerically.The theoretical formula for calculating the passive soil pressure of the limited trapezoidal backfill zone in front of the anchorage structure during construction was put forward,which provides a quantitative basis for the reduction of soil spring stiffness.By analyzing the shear failure mode of steel pile structure during service life,the formula of the ultimate shear bearing capacity of the backfill body was derived.The simplified calculation of bar element based on construction flow was presented and different analysis methods were compared.The results show that the incremental displacements in construction period obtained by the simplified method and the three-dimensional structure-soil integral finite element method are 55 mm and 43 mm respectively,without taking into account the initial controllable displacement;and the displacements in service period are 15 mm and 16 mm respectively.The approximate results verify the reliability of the simplified method.