广州金沙洲地面沉降成因分析

Analysis of land subsidence in Jinshazhou area,Guangzhou City

广州金沙洲是地面沉降危害较严重的地区之一,目前已形成7个沉降区域,沉降总面积约71×104m2,2007年起至2009年3月,是金沙洲地面沉降地质灾害的高发期,这一时期正是某高铁隧道在金沙洲施工阶段。据广州市地质调查院地下水动态监测及地面沉降监测结果,地下水的波动变化与地面沉降具有良好的对应关系,沉降区域沿区内北东向断裂带展布,地面沉降量等值线的展布方向与断裂走向大致一致。各沉降区域沉降中心大多位于断裂带或断裂的交汇部位等特点,据调查,金沙洲地面沉降与软土、正长斑岩风化土、砂土、断裂构造及地下水等因素有关。研究结果表明:复杂的地质环境条件是金沙洲发生地面沉降的客观因素,某高铁隧道施工大量抽排地下水是诱发和加剧地面沉降的主要因素。

Ground subsidence in Jinshazhou has formed seven sinking areas and covered about 710,000 square meters,which is one of the most serious areas in guangzhou.From 2007 to 2009 is the construction stage of a high-speed rail tunnel in Jinshazhou which result the high incidence of ground subsidence in this area.According to the groundwater dynamic monitoring and ground subsidence monitoring results from Guangzhou Institute of Geological Survey,the groundwater fluctuation has a good correspondence with ground subsidence which spread in the direction of the northeast fault zone,ground subsidence contours spreading roughly consistent with the fault strike.Each ground subsidence center area located mostly in the fault zone or fracture intersections.The Jinshazhou ground subsidence has relationship with soft soil,the syenite porphyry weathered soil,sand,fault structures and groundwater.Results of this study show that complex geological environment conditions is the objective factor of Jinshazhou ground subsidence,however,ground subsidence exacerbated by a high-speed rail tunnel excessive pumping of groundwater is principal factor.