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混凝土芯砂石桩能够有效地减少工后沉降和工后差异沉降。为进一步了解混凝土芯砂石桩复合地基的加固机理,预制芯桩对复合地基承载力的提高作用以及砂石壳加速固结排水的作用,采用基于ABAQUS有限元数值分析方法建立轴对称平面应变模型,对混凝土芯砂石桩单桩及单桩复合地基载荷试验进行模拟,并将结果与现场实测数据进行对比。对单桩沉桩过程进行了模拟,并结合圆孔扩张理论和砂井固结理论进行分析。研究结果表明:预制芯桩承担了大部分上部附加荷载,最终荷载分担比约为0.7,有助于提高复合地基承载力;沉桩至5m深度处,地基土隆起对沉桩引起的超孔压影响不大,砂石桩的存在大大加快了地基土中超孔隙水压力的消散和桩周土强度的恢复。
Concrete core sand pile can effectively reduce post-construction settlement and post-construction differential settlement. In order to further understand the reinforcement mechanism of the concrete-filled sand-gravel pile composite foundation, the effect of the precast core pile on the bearing capacity of the composite foundation and the acceleration and consolidation of the gravel shell, the ABAQUS finite element method was used to establish the axisymmetric plane strain model , The load test of concrete-filled sand-gravel pile single pile and single-pile composite foundation was simulated, and the results were compared with the field measured data. The pile sinking process was simulated and analyzed with the theory of hole expansion and sand consolidation theory. The results show that the precast core pile bear most of the upper additional load, the final load sharing ratio is about 0.7, which can help to improve the bearing capacity of composite foundation. When pile sinking to 5m depth, Little effect, the existence of sand pile greatly accelerated the dissipation of excess pore water pressure in foundation soil and soil strength restoration.