宁波平原地面沉降全耦合数值模拟研究

A study of full coupling numerical simulation of land subsidence in the Ningbo plain

宁波地面沉降已有半世纪,随着城市化快速推进,地表动静荷载剧增,地面沉降已从地下水不合理开采的区域性地面沉降逐渐向大规模地表荷载和基坑降排水造成的工程性地面沉降转变。自2008年底市区地下水实施禁限采后,地面沉降漏斗仍继续缓慢扩张,监测中心沉降量持续增加,并相继出现了多个新型小漏斗。在充分论述工程性因素在宁波平原区域地面沉降中作用和特征的基础上,基于有限差分法,建立参数随应力应变变化的地下水开采和区域建筑荷载双重作用下的全耦合动态地面沉降方程。通过实测数据和模拟结果的对比研究,显示模型良好的拟合关系,并预测了2012～2015年地面沉降发展趋势,为宁波地面沉降防治及中心城区城市化建设、海洋经济发展提供依据。

Occurrence of land subsidence has undergone about half a century in the city of Ningbo.With the rapid urbanization and the consequent increasing dynamic and dead load,the cause of the land subsidence has gradually changed from unreasonable groundwater withdrawal to both massive engineering load and foundation pit draining.Since the forbidden draining of groundwater in urban area at the end of 2008,the land subsidence funnel has continued to expand slowly,the subsidence quantity at the land subsidence monitoring center has increased continuously,and many new small funnels have arisen.Based on the full demonstration of the functions and the characteristics of the land subsidence caused by the massive engineering load in theNingbo plain,the full coupling numerical model of the land subsidence resulting from groundwater withdrawal and massive engineering load is established by using the finite difference method in this article.The compared results show that the good fitting relationship between the actual observed value and the predicted value has been attained.Furthermore,the land subsidence development trend in the period of 2012-2015 has been forecast,which will be used as technical bases for land subsidence controlling,urbanization constructing,and marine economy development in the Ningbo plain.