Prediction of Land Subsidence Under Cyclic Pumping Based on Laboratory and Numerical Simulations

Abstract Kerman Province in Iran is confronting with a land subsidence problem due to extensive groundwater withdrawal mainly for farming. In this study land subsidence due to groundwater withdrawal is investigated based on laboratory and numerical models. Since the rate and the type of the groundwater withdrawal has very important impact on consequent settlements and its rate, in this research, the effect of the cyclic pumping on land subsidence is investigated in the laboratory. Sampling is done up to the depth of 300 meters with remolded specimens in Shams-Abad, Nouq plain in Kerman province. Groundwater table oscillation in the field is simulated in laboratory using cyclic loading. One-dimensional consolidation apparatus is adopted for testing. Thicknesses of the samples in consolidation cell and cyclic loading period determined based on dimensional analysis to have the same dimensionless cyclic load time factor with the actual one in the filed. The results of tests show that periodical increases and decreases in the groundwater table level cause the amount of the settlement to decrease in comparison with the case when the groundwater table drops to a constant level. In order to predict further effects of the groundwater level oscillation and actual field conditions on land subsidence, a finite element model based on Biots’ three-dimensional consolidation theory is developed. After calibration the finite element model using laboratory tests’ results, it is used to predict the effect of the groundwater level oscillation on actual field conditions.

 

 

 Keywords Land Subsidence, Laboratory Investigation, Cyclic Loading, Ground Water, Finite Element, Iran