Characterization of land subsidence induced by groundwater withdrawals in the plain of Beijing city, China | Caractérisation de la subsidence induite par les prélèvements d’eaux souterraines dans la plaine de Pékin, Chine Caracterización de la subsidencia del terreno inducida por la extracción de agua subterránea en la planicie de la ciudad de Beijing, China 北京市平原区抽水诱发地面沉降响应特征研究 Caraterização da subsidência do solo induzida por extração de água subterrânea na planície da cidade de Pequim, China
2014
Zhang, Youquan | Gong, Huili | Gu, Zhaoqin | Wang, Rong | Li, Xiaojuan | Zhao, Wenji
The plain of Beijing city in China suffers severe land subsidence owing to groundwater overdraft. The maximum subsidence rate could reach 6 cm/year through the 2000s. An integrated subsidence-monitoring program was designed, including levelling survey, borehole extensometers and multilayer monitoring of groundwater level, with the aim to understand both hydrological and mechanical processes and to characterize the land subsidence. From multilayer compaction monitoring, the major compression layers were identified. The major strata contributing to compression deformation are the second (64.5–82.3 m) and third (102–117 m) aquitards, which contributed around 39 % of the total subsidence. Meanwhile, irrecoverable deformations were also observed in the second (82.3–102 m) and third (117–148 m) confined aquifers; they exhibit elasto-plastic mechanical behavior, which is attributed to the thin beds of silt or silty clay. Stress–strain analysis and oedometer tests were conducted to study the aquifer-system response to pumping and to estimate the specific storage of the major hydrogeologic units. The results reveal the creep behavior and elasto-plastic, visco-elasto-plastic mechanical behavior of the aquitards at different depths. The compressibility of the aquitards in the inelastic range is about one order of magnitude larger than for the elastic range.
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