岩溶区桩端基岩极限承载力及破坏模式试验研究  

The experimental study on limit bearing capacity and failure mode of pile end bedrock in Karst region

作　　者：雷勇[1] 尹君凡 陈秋南[1] 

机构地区：[1]湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室,湘潭411201

出　　处：《应用力学学报》2017年第4期774-780,共7页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(51208195);岩土工程稳定控制与健康监测湖南省重点实验室开放基金资助(E21618)

摘　　要：基于室内模型试验对不同溶洞顶板厚度和位置偏移量下桩端基岩极限承载力及破坏模式进行了研究。试验结果表明:基岩承载力随着溶洞顶板厚度的增加呈线性增长,到5D(D为桩径)时达到完整基岩极限承载力;随着位置偏移量的增大,基岩极限承载力也随之增大;当位置偏移溶洞轴线1.0l(l为洞跨)时,基岩承载力达到完整基岩极限承载力;顶板厚度达到5D时,位置偏移对基岩承载力无影响。溶洞顶板厚度在1D^3D时,在中心荷载作用下破坏模式为冲切破坏,破坏体为一旋转体;随着荷载位置偏移量的增加,破坏模式转变为扇形冲切破坏;当位置偏移量为1.0l时,破坏模式由冲切破坏过渡到桩端基岩塑性区发展破坏;溶洞顶板厚度为4D时,在中心荷载下呈现撕裂和冲切复合的破坏模式;溶洞顶板厚度为5D时,沿溶洞轴线方向发生撕裂破坏并伴随桩端基岩塑性区发展。最后结合规范给出了完整顶板不同厚度时的安全系数。Based on the indoor experiment, the ultimate bearing capacity and failure mode of pile end bedrock in Karst region are studied according to the different thickness of roofs and position offsets. Experimental results show that the bearing capacity of the bedrock increases linearly with the increasing of thickness of cave roofs. When the thickness reaches to 5D(D is the diameter of pile), the bearing capacity can achieve limit bearing capacity of intact bedrock. With the increasing of the position offsets, the limit bearing capacity of bedrock is increased. When the position offset the hole axis is 1.0l, the bearing capacity of bedrock can achieve intact rock limit bearing capacity. When the roof thickness is to 5D, the position offset has no effect on bearing capacity. When the cave roof thickness is in 1D^3D, the failure mode is punching failure under central load and the failure body is a revolution. With the increase of load position offset, the failure mode is transformed into flabelliform punching failure. When the position offset is to 1.0l, the failure mode is from punching failure to plastic failure occurs in bedrock at the bottom of load-plate. When the cave roof thickness is at 4D, the failure mode presents tearing and punching composite failure mode under central load. When the cave roof thickness is at 5D, the tear damage occurs along the axis of the cave and the plastic failure occurs in bedrock of pile end. Finally, the safety coefficients of different thickness of complete roofs are given combined with the specification.

关 键 词：岩溶区 桩端基岩 极限承载力 破坏模式 试验研究 

分 类 号：TU473[建筑科学—结构工程]