桩侧溶洞对桥梁桩基沉降和桩端受力影响分析

Influence of Karst Cave at Pile Side on Settlement of Bridge Pile Foundation and Force of Pile End

以处于灰岩地区的某桥梁工程为依托,建立桩基-溶洞三维仿真模型,分析不同荷载下桩侧溶洞关键尺寸大小对岩溶区桥梁桩基桩顶位移和桩端反力的影响。结果表明:桩侧溶洞高度的增加会导致桩顶位移增大,但对桩端反力影响较小;桩侧溶洞跨度的增大对桩顶位移和桩端反力影响不大;桩侧溶洞跨度相同时,桩顶荷载及高跨比的增大会引起桩基沉降量和桩端反力值增加;桩侧溶洞高度及高跨比较大时,建议增大桩基嵌岩深度,以确保相邻桩基差异沉降量满足要求,桩侧溶洞高度为4~6 m时,可考虑采用强度较低的桩端持力层。

In relation to a bridge engineering in the limestone area,a pile-cave three-dimensional simulation model was established,and the influence of the key size of pile side karst cave under different loads on the pile top displacement and the pile end reaction force were analyzed.The influence laws how the key dimensions,such as cave height,span and height-span ratio,affect the bridge pile settlement and the pile end force o were verified.The results show that,the increased height of pile side karst cave may cause the increased pile top displacement,but has little effect on the reaction force at the pile end;the increased span of pile side karst cave may hardly influence the pile top displacement and the pile end reaction force and,when the span is the same,the increase of the pile top load and the height-span ratio will lead to increased pile settlement and pile end reaction force;where the height of pile side karst cave and the height-span ratio are relatively large,it is recommended to increase the rock-socketed depth of pile so as to ensure the differential settlement of adjacent piles to be in line with the requirements,and when the cave height is 4~6 m,the bearing layer at pile end with lower strength may be considered.