可溶岩地区桩基施工风险预测及工程处理措施

Risk prediction and engineering treatment measures for pile foundation construction in soluble rock area

在武汉市汉口至阳逻江北快速路朱家河大桥的地质勘察中,探测到了厚层第四系粉细砂覆盖可溶岩的不良地质体,使桩基施工及后期大桥运行面临较大风险。从查明岩土结构、探寻岩溶发育规律入手,分析了施工可能引发漏液、岩溶地面塌陷的机理,预测桩基施工中可能出现的风险以及发生的空间范围,提出了相应的工程处理措施:对于裂隙性溶蚀风化区,可采用改善泥浆浓度、预备充足充填材料等常规工程措施;对于溶洞发育区,需采用分层灌浆、护筒跟进等工艺措施,以截断岩溶通道,防止岩溶塌陷。结果表明:施工处理措施有效控制了灌浆孔区域和溶洞漏浆,加快了施工进度。

In the geological survey of the Zhujiahe Bridge from Hankou to Yangluo Jiangbei Expressway in Wuhan City,a serious of geological problems were detected,where the thick Quaternary fine sand directly covered the soluble rocky surface.The pile foundation construction and later bridge operation faced significant risk.By identifying the geotechnical structure and exploring the laws of karst development,this paper analyzed the mechanism of the construction that may result in leakage and karst ground collapse.The possible risk and its influential range in pile foundation construction was predicted,and the corresponding engineering treatment measures were proposed:for the section with fissure corrosion weathering,the conventional engineering measures such as improving mud concentration and preparing sufficient filling materials would be adopted;for the section with karst cave,it was necessary to use layered grouting,drilling with casing and other technological measures to cut off karst channel and prevent karst collapse.The result showed that the engineering measures could effectively control the grouting hole area and the leakage of karst cave,and speed up the construction progress.