基岩裂隙注浆施工技术分析

ANALYSIS OF GROUTING CONSTRUCTION TECHNOLOGY IN BEDROCK FISSURE

以基坑深度25.85m的城建大厦地基与基础工程为例,根据场地勘察报告显示场区内存在2个区域断裂构造影响带及4条小断层;根据渗流分析,基坑开挖后地下水渗流速度较大,主要发生在地铁隧道顶部的砂层及基坑支护结构底部构造破碎岩层段;为防止基坑开挖后地下水通过基坑围护结构底部绕流,导致地铁周边水位变化对地铁隧道变形和基坑底部产生不利影响,在基坑支护结构内外侧增加深层止水帷幕,形成防渗墙,即对基岩裂隙发育区域进行深层止水注浆。

Taking the foundation and foundation engineering of a city building with a foundation pit depth of 25.85 m as an example,the site investigation report shows that there are two regional fault structural influence zones and four small faults in the site.According to the seepage analysis,the seepage velocity of groundwater is large after foundation pit excavation,which mainly occurs in the sand layer at the top of subway tunnel and the broken rock section at the bottom of foundation pit supporting structure.In order to prevent underground water from flowing around the bottom of the foundation pit envelope after foundation pit excavation,causing the change of water level around the subway to have an adverse impact on the deformation of the subway tunnel and the bottom of the foundation pit,a deep water stop curtain is added inside and outside the foundation pit supporting structure to form an anti-seepage wall,that is,deep water stop grouting is carried out in the bedrock crack development area.