| 考虑厚跨比的基桩下伏溶洞顶板冲切特性试验研究 |
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| 引用本文： | 赵明华,唐咸力,肖尧,杨超炜.考虑厚跨比的基桩下伏溶洞顶板冲切特性试验研究[J].岩土力学,2018,39(4):1159-1167. |
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| 作者姓名： | 赵明华 唐咸力 肖尧 杨超炜 |
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| 作者单位： | 湖南大学 岩土工程研究所，湖南 长沙 410082 |
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| 摘 要： | 根据相似理论，设计并完成了4组厚跨比条件下基桩下伏溶洞顶板冲切特性大比例室内模型试验，得到了基桩和顶板的荷载-位移曲线、顶板底面的应变-位移曲线，并分析了桩-溶洞体系冲切特性承载机制。结果表明，基桩荷载-位移曲线在加载过程中出现了两个较为明显的弹塑性区；顶板表面荷载-位移曲线中，厚跨比 和 时的位移在加载过程中出现回弹。与此同时，试验板底面应变变化与底面裂缝的发展趋势相吻合。试验板的冲切破坏是剪切效应和弯曲效应综合作用的结果，随着厚跨比的增大，桩-溶洞体系的极限承载力有所增大，位移量有所减小，剪切效应趋于明显，弯曲效应逐渐消失。冲切锥台的形状随着厚跨比变化显著，厚跨比 时，冲切锥台较为厚实，且沿边界破坏；厚跨比 时，冲切锥台则不受限制。最后，通过分析4组厚跨比条件下试验板冲切锥台，拟合了冲切锥台破坏母线与厚跨比 和基桩直径 的关系曲线，为岩溶区基桩溶洞顶板的理论研究和工程实践提供了依据。
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| 关 键 词： | 岩溶区 桩-溶洞体系 室内试验 冲切破坏 |
| 收稿时间： | 2016-04-25 |
Model tests on punching properties of karst cave roof under pile tip considering different thick-span ratios |
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| ZHAO Ming-hua,TANG Xian-li,XIAO Yao,YANG Chao-wei.Model tests on punching properties of karst cave roof under pile tip considering different thick-span ratios[J].Rock and Soil Mechanics,2018,39(4):1159-1167. |
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| Authors: | ZHAO Ming-hua TANG Xian-li XIAO Yao YANG Chao-wei |
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| Institution: | Institute of Geotechnical Engineering, Hunan University, Changsha, Hunan 410082, China |
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| Abstract: | According to the similarity theory, punching properties of karst cave roof under pile tip were investigated through four series of large-scale laboratory model tests under different thick-span ratios. The load-displacement curves of pile foundation and roof and the strain displacement curves of roof bottom were obtained, and the bearing mechanism of punching feature in the pile-cave system was analysed. The experimental results show that there are two elastic-plastic zones in the pile curve during the loading process. According to the load-displacement curve of the roof, the displacement rebounds at thick-span ratios of 0.125 and 0.200 during the loading process. Meanwhile, the strain change is consistent with the development of cracks at the bottom surface. Punching failure of the test plate is the result of the combined action of the shear effect and bending effect. With the increase of thick-span ratio, the ultimate bearing capacity of the pile-cave system increases slightly, whereas the displacement distance decreases. Shear effect becomes more apparent, while bending effect gradually disappeares. The shapes of the punching cones change significantly with varying the thick-span ratio. When the thick-span ratio is higher than 0.250, the punching cone is relatively thick and destruct along the boundary. While with the thick-span ratio less than 0.200, the punching cone is not restricted. Finally, the relationships among the punching cone generatrix, the thick-span ratio ξ and the pile diameter d are established through analysing the punching cones under four different thick-span ratios. Therefore, this study provides the basis for the theoretical research and engineering practices of karst caves under pile tip in the karst area. |
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| Keywords: | karst area pile-cave system model test punching failure |
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