桩端荷载与地震耦合作用下溶洞顶板的破坏特征及安全厚度计算

发布时间：2018-04-25 01:37

本文选题：岩溶桩基 + 地震作用　；参考：《岩土力学》2017年11期

【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顶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,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,d为桩径)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;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。其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。
[Abstract]:When the pile foundation is supported by the roof of the cave, it is of great significance to study the stability of the roof of the cave end under the earthquake action. Based on the similarity theorem and the separation similarity design method, the dynamic response characteristics of the top plate at the top plate thickness and the diameter of the cave are studied based on the shaking table model test. The results show that the pile end is the end of the pile. The failure mode of the cave roof is closely related to the thickness of the roof and the size of the karst cave. Under the condition of a certain roof thickness, the size of the cave is smaller (the diameter of the hole l < < 2D, and the D as the pile diameter) is shear failure, while the larger the hole diameter (such as l > 4D) is a significant punching shear breaking, the larger the hole diameter, the larger the proportion of the volume of the punching block; The model of the failure of the karst roof has been obtained by the bench test, and a theoretical calculation model of the minimum roof safety thickness which can consider the characteristics of rock mass, seismic intensity and the size of the pile is constructed with the pseudo static method. The minimum safety thickness is larger than the static condition, and increases with the enhancement of the seismic intensity, and the same conditions under the same condition. The calculated values of the scissors shear failure are all larger than the shear failure conditions. It shows that the larger the cave size is, the greater the thickness of the roof is needed. The results can provide a theoretical basis for the calculation of the safety thickness of the karst roof in the actual project.

【作者单位】：福州大学土木工程学院;
【基金】：国家自然科学基金(No.41672290) 福建省自然科学基金(No.2016J01189)~~
【分类号】：TU473.1

【相似文献】