南京河西地区地面沉降成因分析

Cause analysis of land subsidence in Hexi area,Nanjing

为了查明南京河西地区地面沉降的成因,笔者等在系统研究水文地质与工程地质条件的基础上,研究了地面沉降的分布特征和发展规律,以及地面沉降与地下水位、软土分布及建筑荷载之间的关系,进而揭示了南京河西地区地面沉降的成因。研究结果表明:南京河西地区不开采地下水,地面沉降与软土层厚度和建筑荷载分布关系密切,地面沉降主要受建筑工程影响,即建筑荷载和深基坑降水的作用。

Objectives:There is not groundwater exploitation in Hexi area,Nanjing.But land subsidence continues to develop.In order to explore the cause of land subsidence in Hexi area,Nanjing.Methods:Based on the systematic study of hydrogeological and engineering geological conditions.The distribution characteristics and development law of land subsidence,as well as the relationship between land subsidence and groundwater level,soft soil distribution and building load are studied.Furthermore,the causes of land subsidence in Hexi,Nanjing are revealed.Results:The groundwater level in Hexi,Nanjing has been relatively stable in recent 5 years.This is consistent with the condition that groundwater is not exploited.The land subsidence is not affected by groundwater exploitation.Land subsidence is closely related to the thickness of soft soil layer and the density of buildings.On the one hand,the greater the building density,the greater the increase of effective stress of soil mass,resulting in greater land subsidence.On the other hand,pile foundation is usually used for the load of high-rise buildings.And the soil layer is compressed and consolidated under the action of friction.Because the mechanical strength of soft soil layer is lower than that of sandy soil,the land settlement in the area with thick soft soil layer is relatively large.Conclusions:Land subsidence is closely related to the thickness of soft soil layer and the distribution of building load.Land subsidence is mainly affected by buildings engineering.That is,the effect of building load and deep foundation pit dewatering.