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为了研究高置换率挤密砂桩复合地基加固体系的沉降、破坏机理及承载特性,通过自行研发的可视化模型试验装置,进行了单桩、普通置换率与高置换率挤密砂桩复合地基对比模型试验,获得了高置换率挤密砂桩复合地基的荷载-沉降、桩土应力比、沉降-时间及桩土应力比-时间数据。试验结果分析表明:砂桩单桩与群桩复合地基相比,其承载力低,沉降量大;当置换率达到55%以上时,砂桩复合地基承载力提高幅度较大,沉降及桩土应力比随时间效应显著,表明高置换率下砂桩置换作用较明显,可以充分发挥桩间土的承载特性。根据挤密砂桩的承载特性及国内外相关资料,总结了挤密砂桩承载力的计算方法,并采用70%高置换率挤密砂桩室内模型试验进行验证,对比承载力的各种计算方法,为实际工程设计应用提供参考。
In order to study the settlement, failure mechanism and bearing characteristics of the high replacement rate sandstone pile composite foundation consolidation system, the comparison between single sand pile, normal replacement rate and high replacement rate of sand pile composite foundation was carried out by the visual model test equipment developed by ourselves. Model tests, the load-settlement, pile-soil stress ratio, settlement-time and pile-soil stress ratio-time data of high replacement rate sand-pile composite foundation are obtained. The test results show that the bearing capacity of the single sand pile is lower than that of the group pile composite foundation, and the settlement is large. When the replacement ratio is above 55%, the bearing capacity of the sand pile composite foundation increases greatly, The effect of stress ratio over time is significant, indicating that the replacement effect of sand pile under high replacement rate is obvious, and the bearing capacity of soil between piles can be fully exerted. According to the bearing characteristics of the compacted sand pile and relevant data at home and abroad, the calculation method of the bearing capacity of the compacted sand pile is summarized and verified by the indoor model test of 70% high replacement rate compacted sand pile. Comparing various calculation methods of bearing capacity Method for the actual engineering design and application of reference.