大直径旋喷锚索在广州岩溶发育地区基坑工程中的应用研究

Study on the Application of Large-diameter Jet Grouted Anchor Cable in Foundation Pit Engineering in the Karst Development Area of Guangzhou

为研究大直径旋喷锚索在岩溶地区基坑工程中的应用效果,以广州市白云区某岩溶发育地区基坑工程为依托,详细分析了灌注桩+大直径旋喷锚索支护体系在岩溶发育地区中的设计方案和实施效果,同时对大直径旋喷锚索的施工工艺进行了现场优化。研究结果表明:采用现场优化工艺的大直径旋喷锚索的施工效率较常规工艺提高约32%。对于粉质黏土中的大直径旋喷锚索,要使其锚固体直径达到400 mm,则其单管旋喷压力需要达到20 MPa以上。灌注桩+大直径旋喷锚索基坑支护结构的深层水平位移和周边地面的沉降以及大直径旋喷锚索的抗拔力处于合理可控范围。采用灌注桩+大直径旋喷锚索作为岩溶发育地区基坑的支护结构是安全可靠的,研究成果可为广州地区类似基坑工程项目提供借鉴与参考。

In order to investigate the application effect of large-diameter jet grouted anchor cable in foundation pit in karst area,based on the foundation pit engineering in Baiyun district,Guangzhou city,the design scheme and implementation effect of the filling pile and large-diameter jet grouted anchor cable support system in the karst development area are analyzed in detail,and the construction technology of the large-diameter jet grouted anchor cable is optimized on-site.The results show that the construction efficiency of the large-diameter jet grouted anchor cable with the on-site optimization process is approximately 32%higher than the conventional process.For the large-diameter jet grouted anchor cable in silty clay,in order for the diameter of the anchor body to reach 400 mm,the single-pipe jet grouted pressure must be more than 20 MPa.The deep horizontal displacement and settlement of the surrounding soil of the foundation pit supporting structure of the filling pile and large-diameter jet grouted anchor cable and the reasonable controllable range of the anti-pulling force of the large-diameter jet grouted anchor cable are adopted;the filling pile and large-diameter jet grouted anchor cable are safe and reliable as the foundation pit supporting structure in the karst development area.The research results can serve as a reference for similar excavation projects in Guangzhou.