SIMULATION OF LAND SUBSIDENCE IN COASTAL AREAS OF TANGSHAN WITH A SEEPAGE-CONSOLIDATION COUPLING MODEL

Accompanying with the rapid economic growth and urbanization expansion of the coastal areas of Tangshan, the quantity of groundwater exploitation has increased and land subsidence has aggravated. We analyze the hydrogeology condition in this region, and generalizes it into six compressed layers including three aquifers and three aquitards. A fully coupling model of three-dimensional groundwater flow and vertical one-dimensional compression is constructed. The simulation data, derived from the model calibrated with a 25 years observational data, are fitted well with the measured values, which verifies the model validity. According to our prediction, subsidence amount in subsidence center will be accumulatively up to 1192.3mm after 10 years. The subsidence over ten years will reach 352.3mm and the average subsidence rate will attain to 35.23mma-1 under present groundwater exploitation. If the amount of groundwater extraction increases 10%on the basis of existing mining quantity, the subsidence amount in subsidence center will achieve 1260.8mm. The subsidence amount in ten years will grow up to 420.8mm and the average subsidence rate will be 42.08mma-1.If reducing the groundwater extraction in 10%based on the existing mining quantity, at subsidence center the subsidence amount will accumulate to 1088.7mm. Subsidence amount in ten years will reach 247.9mm and the average subsidence rate will be 24.79mma-1. Subsidence amount over ten years will increase 68.5mm if the groundwater exploitation extends 10%, and it will decrease 104.4mm if the groundwater extraction reduces 10%.In summary, limiting the groundwater withdrawal is an effective method to control the land subsidence.