北京南部沉降区黏土层变形特征和参数分析  

Analysis of Deformation Characteristics and Parameters of Clay Layers in South Subsidence Area of Beijing

作　　者：尤斌昊 叶淑君[1] 田芳[2] 罗勇[2] YOU Binhao;YE Shujun;TIAN Fang;LUO Yong(School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;Beijing Institute of Hydrogeology and Engineering Geology,Beijing 100195,China)

机构地区：[1]南京大学地球科学与工程学院,南京210023 [2]北京市水文地质工程地质大队,北京100195

出　　处：《高校地质学报》2023年第4期590-599,共10页Geological Journal of China Universities

基　　金：国家自然科学基金项目(批准号:41877180);北京市财政项目(PXM2019_158305_000012)联合资助。

摘　　要：北京地面沉降分南北两个大区,南部沉降区主要为礼贤—榆垡沉降区,近年该区沉降速率加快,2017~2019年沉降速率达50~75 mm/a,沉降呈现新的特征。文章基于该沉降区唯一的沉降观测站(榆垡沉降监测站)2011~2017年7年长时间序列的沉降和水位观测资料,首先系统分析了该地区地面沉降监测孔监测地层尤其是黏土层的变形特征,然后运用应力—应变图解法和配线法计算该区黏土层的弹性贮水率、非弹性贮水率、垂向渗透系数和变形滞后时间。结果表明,各土层既有弹性变形又存在塑性变形,变形均以塑性变形为主,有明显的变形滞后性;但各土层在变形速率上呈现不同特征。图解法结果表明,第一和第二黏土层非弹性贮水率在1.49×10^(-5)~2.10×10^(-5)之间,弹性贮水率在3.93×10^(-5)~8.38×10^(-5)之间,非弹性贮水率为弹性贮水率的2~4倍,垂向渗透系数在6.20×10^(-6)~4.39×10^(-5 )m/d之间,土层变形滞后时间为2.1~12.8年。配线法估算出研究区浅部土层的贮水率在4.8×10^(-4)左右,深部土层的贮水率在1.08×10^(-4)~2.05×10^(-4)之间,浅部土层的贮水率是深部土层的2~4倍,浅部土层垂向渗透系数比深部土层大1~2个数量级。The land subsidence in Beijing is divided into north and south areas,and the southern area mainly includes Lixian-Yufa subsidence zone.The subsidence rate in this area has accelerated in recent years and reached 50-75 mm/a during 2017-2019,showing new subsidence characteristics.Based on the subsidence and water level observation data of 7-year time series from 2011 to 2017 at Yufa Subsidence Monitoring Station,the only subsidence observation station in the south subsidence area.The deformation characteristics of soil layers,especially clay layers,are systematically analyzed.Then the elastic and inelastic specific storage,vertical hydraulic conductivities and deformation lag time of the clay layers are estimated by the stress-strain diagram method and the type curve method.The results show that there are both elastic deformation and plastic deformation in each soil layer,and the plastic deformation is the main deformation with obvious deformation hysteresis.However,the deformation rate of each soil layer presents different characteristics.The results of the stress-strain diagram method show that the inelastic specific storage of the first and second clay layers is between 1.49×10^(-5) and 2.10×10^(-5),the elastic specific storage is between 3.93×10^(-5) and 8.38×10^(-5),the inelastic specific storage is 2^(-4) times of the elastic specific storage,the vertical hydraulic conductivity is between 6.20×10^(-6)~4.39×10^(-5) m/d,and the soil deformation lag time is 2.1-12.8 years.The specific storage of the shallow layers in the study area estimated by the type curve method is about 4.8×10^(-4),and that of the deep layer is between 1.08×10^(-4) and 2.05×10^(-4).The specific storage of shallow layer is 2^(-4) times of that of deep layer,and the vertical hydraulic conductivities are 1-2 orders of magnitude larger than that of the deep layers.

关 键 词：地面沉降 黏土层 变形特征 水文地质参数 图解法 配线法 

分 类 号：P641[天文地球—地质矿产勘探]