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采用离心机模型试验和三维有限元模型对天兴洲大桥的超长嵌岩钻孔灌注群桩进行了分析.离心机试验中,根据相似理论,不同的原型材料用不同的指标进行模拟,细砂、桩身、承台分别以天然密度、抗压刚度、抗弯刚度作为指标进行模拟.对土体未开挖阶段、钻孔阶段、混凝土灌注阶段和养护阶段的应力场进行了详细的讨论,并应用ANSYS进行了分析.根据2种方法得到的结果,从荷载沉降曲线、桩身轴力分布和侧向摩阻分布等方面,对比分析了加载和卸载条件下超长钻孔群桩的承载特性.结果表明,有限元计算模型与离心机试验模型沉降观测的结果吻合得很好;桩顶反力的分布规律复杂,与承台的自身刚度、相应的假定和分析方法有关;轴力随着深度先稍微增加,后逐渐减少,并且在岩层中减少的速度远比砂土中快.
Centrifuge model test and three-dimensional finite element model were used to analyze the overlength rock-socketed perfusion pile in Tianxingzhou Bridge.According to the similarity theory, different prototype materials were simulated with different indexes Sand, pile body and bearing platform are simulated with natural density, compressive rigidity and flexural rigidity respectively. The stress field of the soil in the non-excavation stage, the drilling stage, the concrete pouring stage and the curing stage are discussed in detail , And analyzed by ANSYS.According to the results obtained by the two methods, from the load settlement curve, the distribution of axial force and the lateral frictional distribution, the pile groups of overlength drilling groups under loading and unloading conditions were comparatively analyzed The results show that the finite element calculation model is in good agreement with the sedimentation observation results of centrifuge test model. The distribution law of pile top reaction force is complex, which is related to the self-rigidity of caps and corresponding assumptions and analysis methods. As the depth increases first and then decreases, it decreases much more rapidly in the formation than in the sand.