基于修正麦钦特模型的地面沉降模拟:以上海为例

Land subsidence modeling based on the modified Merchant model:A case study of Shanghai

中国很多发生地面沉降的城市,如上海、苏州、无锡、常州等地,土层变形呈现粘弹塑性变形特征,并且粘弹塑性变形在总的沉降中占很大比例.比如,1986-1997年间上海市地面沉降量的84%到98%由土层的粘弹塑性变形引起.修正的麦钦特模型(MM模型)是一种描述粘弹塑性变形的新模型.刻画粘弹塑性变形的地面沉降模型(LS-MM模型)是基于MM模型推导出的一种新的地面沉降模型.本文以上海市具有粘弹塑性变形特征的土层为例,通过数值模拟计算验证MM模型和LS-MM模型.结果表明,MM模型和LS-MM模型能很好的模拟土层的粘弹塑性变形,如考虑参数随沉降变化则能提高模拟精度.只有4个参数且能描述各种变形特征的优点使LS-MM模型适用于具有复杂变形特征的大型区域地面沉降模拟.

Some sedimentary layers present visco-elastic-plastic deformation in many cities in China, like Shanghai City, Suzhou City, Wuxi City and Changzhou City etc. Land subsidence was to a large extent caused by the viscoelastic-plastic deformation of some sediments in these cities. For example, 84% to 98% of the total subsidence in Shanghai City is caused by the visco-elastic-plastic deformation of sediments. The modified Merchant model （MM model） is a new model to describe visco-elastic-plastic deformation. A new land subsidence model （LS-MM model） is developed based on the MM model to simulate land subsidence caused by visco-elastic-plastic deformation. Numerical experiments are done on the sediments with visco-elastic-plastic deformation in Shanghai to verify the MM model and LS-MM model. The results indicate that MM model and LS-MM model can simulate compaction of sediments with visco-elastic plastic deformation, and results can be improved by variable parameters （especially specific storage）. The advantages of only four parameters involved and embodying all kinds of deformation make the LS-MM model flexible and applicable to the simulation of the large regional land subsidence with visco-elastic-plastic deformation and other different kinds of deformation.