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被动桩侧向土压力的群桩效应是研究被动桩的重要问题。运用岩土数值计算程序FLAC3D,对土体沿深度发生均匀侧移,桩基两端简化为铰接的刚性双桩基础(桩中心连线与土体位移方向平行)进行研究。土体采用摩尔-库伦本构关系,桩基采用线弹性本构关系,桩土之间建立接触面。结果表明,在土位移增加的过程中,两桩侧向土压力均小于单桩,呈近桩大、远桩小。在浅层土体,加筋效应很小,但遮拦效应明显。在深层土体内,加筋和遮拦效应都很显著,p—δ曲线形状与单桩明显不同,在经历较短直线增长后,沿曲线增长至极限土压力,达到桩侧极限土压力所需的桩土相对位移量明显增加,当桩间距增长至6 D,群桩效应基本消失。最后与室内模型试验所得到的桩侧极限土压力群桩效应系数进行了对比分析。
Pile group effect of lateral pressure of passive pile is an important issue to study passive pile. The geotechnical numerical calculation program FLAC3D is used to study the uniform lateral displacement of soil along the depth and the simplified rigid double-pile foundation (parallel to the soil displacement direction) of the pile at both ends of the pile. Soil Moore - Coulomb constitutive relationship, the pile foundation using linear elastic constitutive relations, pile-soil contact surface between the establishment. The results show that in the process of increasing soil displacement, the lateral earth pressure of the two piles is less than that of a single pile, with a large near pile and a small far pile. In shallow soil, the reinforcing effect is very small, but the obstruction effect is obvious. In deep soil, the effect of reinforcement and obstruction is significant. The shape of p-δ curve is obviously different from that of single pile. After experiencing a relatively short linear growth, the curve increases to the limit earth pressure and reaches the limit earth pressure on pile side The relative displacement of pile and soil increased obviously. When the pile spacing increased to 6 D, the pile group effect basically disappeared. Finally, the pile-effect coefficients of pile-group limit earth pressure obtained by indoor model test are contrasted and analyzed.