【作者】 陈福全； 黄明； 付俊杰； 江松；

【Author】 Ming Huang;Jun-jie Fu;Fu-quan Chen;Song Jiang;College of Civil Engineering,Fuzhou University;

【机构】 福州大学土木工程学院；

【摘要】 桩基支撑于溶洞顶板的情况时有发生,研究地震作用下桩端溶洞顶板的稳定性具有重要意义。根据相似定理和分离相似设计方法,基于振动台模型试验对项板厚度及溶洞直径变化下桩端顶板的动力响应特征进行了研究。结果表明,1)桩端溶洞顶板在地震作用下的破坏模式与顶板厚度及溶洞尺寸大小密切相关,一定顶板厚度情况下溶洞尺寸较小时(洞径l≤2d)表现为剪切破坏,而洞径较大时(如l≥4d)为显著的冲剪破坏,洞径越大冲切块体积所占比例越大。2)基于振动台试验得到的岩溶顶板破坏模式,结合拟静力法构建了可考虑岩体特性、地震烈度及桩径大小影响的最小顶板安全厚度理论计算模型,通过算例分析表明,最小安全厚度相比静力条件下要大,且随地震烈度的增强而增大,相同条件下冲-剪破坏的计算值均大于剪切破坏情况,说明地震环境下溶洞尺寸越大所需顶板厚度越大。成果可为实际工程中岩溶顶板安全厚度的计算提供理论基础。更多还原

【Abstract】 It is of great significant to study the cave roof stability and its safety thickness coupled the earthquake affection and pile load.With the similarity theorem and the separation similarity design method,the dynamic failure characteristics of the cavern roof under the change of roof thickness and cave diameter were studied by the shaking table model test.It shows that,1) The failure modes of cave roof coupled by earthquake and pile-load affection are closely related to the size of the cave.When the thickness of roof is determined and the cave-diameter is smaller than 2 d(where d is the pile-diameter),shear failure will happen in the roof observably.On the contrary,when the cave-diameter is larger than 4 d,punching-shear failure will occur.2) In terms of the quasi-static method and the failure characteristics of the roof,two kinds of theoretical solutions for the minimum thickness of cave roof,which can take account of the mechanical properties of rock,seismic intensity and pile-diameter were presented.According to the analyzing results,the stronger the seismic intensity the greater the minimum thickness of cave roof,and the safety thickness of cave roof increases with the increment of the size of karst cave.Those investigation results can provide reference to develop the design approaches for the karst-pile in the earthquake region.更多还原