多层加筋垫层刚性桩网复合地基的承载特性

为研究多层加筋垫层刚性桩网复合地基的承载特性，将设置有多层土工格栅的加筋垫层视为大挠度薄板进行分析，运用层合板理论，模拟多层土工格栅与碎石垫层之间的相互作用，建立加筋垫层抗弯刚度矩阵的计算方法。考虑刚性桩网复合地基的三维应力和位移边界条件，根据静力平衡条件，建立加筋垫层应力函数和挠度微分控制方程，并利用伽辽金方法进行求解。在此基础上，利用Winkler地基梁理论和大挠度薄板理论对桩土应力比和格栅拉力进行计算。最后，运用实际工程对计算方法进行验证，并综合分析格栅总层数、铺设间隔和位置等因素对桩土应力比及格栅拉力的影响。研究结果表明：理论计算结果与实测结果较为吻合；随着格栅总层数的增大，桩土应力比增大而格栅拉力降低，铺设2~3层格栅效率最高；随着铺设格栅间隔和底层格栅距桩帽距离的增大，桩土应力比降低，而格栅拉力增大。

Analysis of bearing capacity of rigid pile-net composite foundation with multi-layer reinforced cushion

This study aims to explore the bearing characteristics of rigid pile-net composite foundation with multi-layer reinforced cushion. Firstly, the reinforced cushion layer with multi-layer geogrids is regarded as a large deflection plate for simplification. The interaction characteristics between multi-layer geogrids and gravel cushions were analyzed based on laminating theory. The stiffness matrix of reinforced cushion was then derived. Considering the actual three-dimensional stress and displacement boundary of the rigid pile-net composite foundation, the stress function and the deflection differential control equations were deduced through the static equilibrium. Subsequently, Galerkin method was used to solve the equations. Based on the deformation of the reinforced cushion layer, the pile-soil stress ratio of rigid pile-net composite foundation was calculated through Winkler foundation beam method and the tension force of geogrids was derived via large deflection plate theory. Finally, the calculation method was validated by practical engineering. The factors that affect pile-soil stress ratio and tension force, such as total number of geogrids, geogrids spacing and location of the geogrids, were systematically analyzed. It is shown that the analytical solutions agree well with the measured data. With increase of the total number of geogrid layers, the pile-soil stress ratio increases and the geogrid tensile force decreases. The most efficient number of geogrid layers is 2 or 3. With the increase of vertical spacing between geogrids and the spacing from the bottom geogrid to pile cap, pile-soil stress ratio decreases and tension force increases. More importantly, these findings may provide guidance on optimal design of geogrid in engineering practice.