断层破碎带隧道施工阶段围岩分级研究

Study of Surrounding Rock Classification during Tunnel Construction Stage In Fault and Fractured zone

由于隧道里程过长和勘察手段的局限性,常常导致勘察阶段确定的围岩等级与实际情况存在一定误差,这容易造成工程造价增加、影响施工安全等问题。以港珠澳大桥连接线上的南湾隧道为例,选取了穿越断层破碎带且靠近水库的里程段为研究对象,系统介绍了通过隧道施工阶段的点荷载试验和监控量测资料来定量确定围岩分级各个指标的方法。结果表明,采用BQ围岩分级法可以在施工阶段快速、准确地确定了围岩分级;实际围岩分级为Ⅳ级,修正了勘察阶段所确定的V级围岩;分级结果为调整工程方案提供了重要依据,并有效地节约了工程造价、加快了工程进度。

Due to overlong tunnel and limited investigation technique, surrounding rock grade at geotechnical investigation stage is usually inconsistent with the actual situation, which can lead the increase of engineering cost and affect construction safety. By taking the Nanwan Tunnel in the connecting line of the Hong Kong-Zhuhai-Macao Bridge as an example, a special section of tunnel is chosen as the study subject since it goes through a fault fracture zone and is close to a reservoir. This paper makes a systematic introduction to a quantitative classification method of each index of surrounding rock classification which is based on point load tests and monitoring measurement data. The results show that：surrounding rock classification method BQ can quickly and accurately determine the grade of surrounding rock in construction stage; actual surrounding rock classification is the fourth class while it was determined as fifth class at geotechnical investigation stage; the obtained classification results can provide important basis for adjustment of engineering scheme, effectively save the engineering cost, and speed up the engineering progress.