T he reconstruction project for the Xiongchu Avenue in Wuhan adopts the scheme of viaduct + BRT (bus rapid transport) under the viaduct + ground auxiliary road .The main line viaduct is designed as a continuous beam bridge with spans of 40 m ,the width of which is about 26 m with dual six lanes three lanes on each side .The dominant adverse geological condition around the construction site is the Karst topography .The design was carried out in accordance with the substructure of urban bridges in Karst areas .By the comprehensive comparison and selection of the schemes of vase‐shaped pier ,frame pier and single‐columned pier ,the single‐columned pier was fi‐nally chosen as the main form of piers .To ensure the accuracy of geological survey ,two or three geological drilling holes are needed for each pile .According to the actual condition at the construc‐tion site ,a basic rock‐embedded depth of 2 .5 times of the pile diameter was determined .The bed‐rock roof models for simply‐supported beam ,cantilever beam and fixed beam were established ,and by the results of calculation and analysis and data comparison ,the minimum safety thickness for the bedrock roof was determined .For the problem of Karst pile foundation leakage ,a series of measures were taken ,such as rip‐rap filling ,grouting before the steel casings were driven .%武汉市雄楚大街改造工程采取高架桥＋桥下BRT （公交车捷运系统）＋地面辅道形式。其中主线高架桥主要采用40 m跨度的连续梁，桥面宽约为26 m ，为双向6车道。工程场地沿线最主要的不良地质为岩溶，针对岩溶发育地区的城市桥梁下部结构进行设计。对花瓶墩、框架墩、独柱墩进行综合比选，最终确定了以独柱墩为主的桥墩结构形式。为确保地质勘探的准确性，每根桩至少要有2或3个地质钻孔。根据现场实际情况，结合相关文献，确定了2．5倍桩径的基础嵌岩深度。建立简支梁、悬臂梁以及固结梁的基岩顶板模型，并通过计算分析和数据对比，确定最小顶板安全厚度。针对溶洞漏浆问题，采取了抛填片石、预先注浆以及钢护筒跟进的处理措施。
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