岩溶区嵌岩桩承载特性影响因素试验研究

基于室内模型试验，对岩溶区嵌岩桩承载能力的影响因素进行了研究。试验表明，随顶板厚度与溶洞位置偏移距离的增大，极限承载力逐渐增大，随溶洞直径、赤道半径与极半径的增大，极限承载力逐渐减小；破坏核体在竖直方向上基本未超过3d（d为桩体直径）范围，在水平方向上基本未超过4d范围。结合模型试验结果，影响因素的敏感性分析表明，敏感度大小的顺序为：溶洞直径>顶板厚度、赤道半径>极半径>溶洞位置。嵌岩桩的承载能力还与溶洞形状有关，厚径比为溶洞顶板厚度、赤道半径以及桩体底面积的综合影响因素，建议引进形状系数? 与底面积尺寸效应系数?，提出岩溶区嵌岩桩概念设计的注意事项，并通过工程实例进行了验证，现场静载试验与模型试验结果基本一致，楼房竣工后未发生岩溶危害。

Test research on factors influencing bearing capacity of rock-socketed piles in karst area

Based on indoor model tests, the research on factors influencing bearing capacity of rock-socketed piles in karst area is carried out. The tests indicate that, with the increases of roof thickness and cave migration position, the ultimate bearing capacity increases gradually; with the increases of cave diameter, equatorial and polar radius, the ultimate bearing capacity decreases gradually. The failure zones are less than 3d range at vertical direction and less than 4d range at horizontal direction. Combined with the model test results, the analysis of influencing factor sensitivities show that, the size order of sensitivities is cave diameter, roof thickness and equatorial radius, polar radius, cave position. The bearing capacity of rock-socketed pile also had relation with cave shape; ratio of thickness to radius is a comprehensive affecting factor with cave thickness, equatorial radius and pile bottom area. The shape factor ?, bottom area size effect ? and notices of conceptual design are introduced to evaluate the bearing capacity of rock-socketed pile, which are verified by engineering examples. The field test results are in agreement with the model test results, and the karst problems not occurred after building completion.