唐山沿海地区地面沉降渗流固结耦合模拟研究

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

唐山沿海地区经济在迅速发展,沿海地区城市化规模在扩大,地下水开采量增大,地面沉降加剧。文中分析了唐山沿海地区的水文地质条件,概化为3个含水层、3个弱透水层,共6个压缩层。建立了三维地下水流和垂向一维压缩完全耦合模型。采用25a的观测资料校正模型,计算值与实测值拟合较好,模型具有较高的仿真性和适用性。预测了10a末的地面沉降;当地下水以现有开采量开采时,沉降中心累计达1192.3mm,10a沉降352.3mm,沉降速率为35.23mm·a-1;当地下水的开采量在现有开采量的基础上增加10%时,沉降中心累计达1260.8mm,10a沉降420.8mm,沉降速率为42.08mm·a-1;当地下水的开采量在现有开采量的基础上减小10%时,沉降中心累计达1088.7mm,10a沉降247.9mm,沉降速率为24.79mm·a-1。增大10%的地下水开采量,10a地面沉降量增加68.5mm;减少10%的地下水开采量,10a地面沉降量减少104.4mm。因此,控制地下水开采量是控制地面沉降的有效方法。

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 35.23mm·a-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 42.08mm·a-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 24.79mm·a-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.