西安地铁沿线地面沉降活动趋势及危险性评价

The Activity Trend and Risk Assessment of Land Subsidence along Metro Lines in Xi'an City

地面沉降是西安市典型城市地质灾害之一,严重制约了西安城市地下空间的开发和利用,尤其是严重阻碍了城市轨道交通的发展。地层不均匀沉降变形增大,使地铁隧道衬砌结构产生纵向开裂破坏和隧道渗漏水等病害,这给西安地铁的建设及运营留下安全隐患。本文基于2007—2012年间120个地面沉降监测点的监测数据,根据等速率外推法预测了地铁沿线未来的地面沉降活动速率,运用单位变形量法计算出了地铁沿线地面沉降最大沉降量,其中胡家庙地面沉降中心最大沉降量为1 960 mm,小寨、大雁塔、沙坡及西工大等地面沉降中心为400～700 mm,而辛家庙、含元殿地面沉降中心为200～300 mm。结合地铁工程自身的特点和重要性,对地铁沿线各区域地面沉降的危险性进行了评价,认为区域地面沉降对地铁线路的影响主要集中在地面沉降中心范围内,整体上线路南段危险性明显大于中段和北段。研究结果可为西安地铁工程规划设计、施工建设及安全运营提供重要依据。

Land subsidence is one of the most typical urban geological hazards in Xi’an,China,which seriously restricts the development and utilization of Xi’an urban underground space, especially severely hinders the development of urban rail traffic. The uneven stratum settlement often induces the longitudinal cracking failure of metro tunnel lining structure and leakage and other metro diseases,which brings potential safety hazard to Xi’an metro construction and operation. Therefore,based on the field monitoring data of 120 land subsidence monitoring points from 2007 to 2012,the method of equal velocity extrapolation was proposed to predict the trend of the land subsidence along the metro lines and the largest settlement value was predicted with the method of the unit deformation. It is concluded that the maximum subsidence of Hujia temple land subsidence center is up to 1960 mm,the maximum subsidence of Xiaozhai,Great Wild Goose Pagoda,the Xi Gongda land subsidence center is about400 ~ 700 mm,and the maximum subsidence of Xijia temple,Hanyuan temple land subsidence center is about 200 ~300 mm. The regional land subsidence geohazard along the metro lines was evaluated according to the characteristics and importance of the metro engineering. The results show that the influence of regional land subsidence on metro lines is mainly concentrated in the range of land subsidence center,and the risk of the southern section of metro lines significantly greater than the middle and northern sections. The above results can provide an important reference for Xi’an metro construction and safe operation.