ISSN 1000-3665 CN 11-2202/P

    抗滑桩应变特征与内力非线性研究

    A study of the strain characteristics and internal force nonlinearity of anti-slide pile

    • 摘要: 为探究抗滑桩实际内力与变形间的规律,特别是桩土相互作用下桩体受力、变形、稳定性等特征,通过抗滑桩大型物理模型试验,结合MATLAB拟合推导实现从桩表面应变散点数据到桩身挠度分布的求解。对比同桩长不同加载条件与同加载条件不同桩长两种情况下桩表面应变、桩身弯矩、剪力及挠度,分析抗滑桩的应变特征与内力变化规律。研究表明:单调与循环加载条件下抗滑桩工作阶段划分为三阶段,即未开裂阶段、混凝土开裂-钢筋屈服阶段、钢筋屈服-桩体破坏阶段。未开裂阶段一、二级荷载下由于土的压密性桩体略微回弹,桩表面应变、桩身弯矩、受荷段剪力及挠度出现较小的负值(绝对值约为破坏时的1%)。混凝土开裂-钢筋屈服阶段应变、弯矩、剪力、挠度增速明显加快。钢筋屈服-桩体破坏阶段应变、弯矩、剪力、挠度呈非线性增长,桩体的破坏模式均为弯剪破坏。随着自由端长度的增加,破坏时应变、弯矩增大,而剪力减小,破坏时应变增长约10%,弯矩增长约3%,剪力减少约20%;相对于单调加载,循环加载下最大弯矩值和最大挠度均有增大,最大弯矩增长约2%,最大挠度增长约1%。

       

      Abstract: This paper presents an investigation of regularity between the internal force and deformation of anti-slide pile under the actual stress condition, places its emphasis on the regularity of force characteristics, deformation and stability of pile body under the interaction between anti-slide pile and soil. Based on experimental data of large physical model tests of anti-slide pile, and fitting the data with MATLAB, the solution from the strain data of pile surface to the deflection diagram of pile body is realized. The regularity between the strain characteristics and internal force variation of anti-slide pile are analyzed by comparing the strain of pile surface, bending moment of pile body, shear and deflection in the two conditions: different loading conditions under the same pile length and different pile lengths under the same loading condition. The results demonstrate that the working stage of anti-slide pile under the condition of monotone and cyclic loading is divided into three stages: the uncracked stage, concrete cracking-steel yield stage and steel yield-pile destroying stage. Under the first and second load levels in the uncracked stage, the stain surface of pile, the bending moment of pile body, the shear force of the load section and deflection appear smaller negative values due to the slight rebound of the compaction pile body of the soil, and the absolute values of the smaller negative values are about 1% the values at the pile destroying stage. The growth rates of strain, bending moment, shear force and deflection of concrete cracking-steel yielding stage are obviously accelerated. Strain, bending moment, shear force and deflection of steel yielding-pile destroying stage show nonlinear growth, and the failure modes of pile body are all bending and shear failure. As the length of the free end increases, strain and bending moment increase by about 10% and 3% at the pile destroying stage, while the shear force decreases by about 20%. Compared with the monotonic loading, the maximum bending moment and maximum deflection increase by about 2% and 1% respectively under cyclic loading.

       

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