Experimental study on Su-Xi-Chang earth fissures induced by repeated groundwater pumping and impounding

• Main Authors: Jishan Xu, Jianbing Peng, Haibo An
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2019-01-01
• Series: Geomatics, Natural Hazards & Risk
• Subjects: earth fissures; groundwater impounding and pumping; su-xi-chang area; physical model; land subsidence
• Online Access: http://dx.doi.org/10.1080/19475705.2019.1676832
• ISSN: 1947-5705; 1947-5713

Surface subsidence and fissures, especially surface fissures, are typical geological disasters related to groundwater activities in the Su-Xi-Chang area, China. In this study, we first analysed the geologic background and hydraulic features of earth formation in the area and constructed a physical model and its related experimental system in the laboratory. Based on the model and the system, we further experimentally studied and theoretically analysed the mechanism of ground fissure formation. The results showed that development of the earth fissures obviously undergoes the following stages. First, under self-gravity, the soil (artificial sand) layers in the model box with larger void ratios are gradually compacted, leading to uneven surface subsidence. Second, although the excess pore-water pressure could cause the surface to rise locally and macroscopically, water impounding on the aquifer lowers the friction among sand grains to certain degree depending on the strength of seepage in the horizontal direction, resulting in surface deformation and subsidence. Third, strong water pumping instantaneously releases excess pore-water pressure, resulting in soil consolidation in the vertical direction. Therefore, repeated groundwater impounding and pumping together with unique geological conditions lead to the formation of earth fissures in the Su-Xi-Chang area.