CAJ | 학술논문

近年来上海地区的地面沉降出现了第四承压含水层持续变形及滞后的新特征，传统土力学已不能完全解释其机理。针对上海地面沉降发展新变化，已有的研究从如下方面进行了探讨：针对沉降加剧现象，分析了城市化建设对地面沉降的影响；从砂土材料的蠕变性状出发，分析深部含水层过大变形的现象。上述两方面虽在一定程度上可解释沉降新特征，但还是不能完全阐明其发生机理。基于此，本文提出考虑含水层抽水后受力状态随空间与时间再分布的两种动态传力机理分析方法：（1）基于Cosserat力学体系的地面沉降模型考虑了水力梯度变化在砂土层中产生的剪应力，给出了考虑固结效应的Cosserat介质力学模型，可以很好地从含水层受力机理的角度解释含水层持续变形增大和变形滞后的发生机理；（2）水的渗透会对土骨架产生拖曳力，使粘性土的细颗粒在粗颗粒构成的孔隙中移动，发生内部侵蚀流动造成细颗粒流失，阐述了考虑细颗粒流失作用对地面沉降的影响及其地面沉降在含水层空间与时间重分布的发生机理。
근년래상해지구적지면침강출현료제사승압함수층지속변형급체후적신특정，전통토역학이불능완전해석기궤리。침대상해지면침강발전신변화，이유적연구종여하방면진행료탐토：침대침강가극현상，분석료성시화건설대지면침강적영향；종사토재료적연변성상출발，분석심부함수층과대변형적현상。상술량방면수재일정정도상가해석침강신특정，단환시불능완전천명기발생궤리。기우차，본문제출고필함수층추수후수력상태수공간여시간재분포적량충동태전력궤리분석방법：（1）기우Cosserat역학체계적지면침강모형고필료수력제도변화재사토층중산생적전응력，급출료고필고결효응적Cosserat개질역학모형，가이흔호지종함수층수력궤리적각도해석함수층지속변형증대화변형체후적발생궤리；（2）수적삼투회대토골가산생타예력，사점성토적세과립재조과립구성적공극중이동，발생내부침식류동조성세과립류실，천술료고필세과립류실작용대지면침강적영향급기지면침강재함수층공간여시간중분포적발생궤리。
Recent land subsidence in Shanghai has fol owed a new pattern whereby the subsidence and deformation of the aquifer increase continuously, but the deformation lags the recovery in the groundwater level. Existing approaches to land subsidence prediction cannot reasonably interpret these phenomena. Consequently, new research was conducted to investigate the mechanisms associated with the new phenomena of land subsidence in Shanghai：i） the inlfuence of urban construction on increased land subsidence was investigated;and i ） the creep characteristics of sandy soil were analyzed to investigate the causes of increased aquifer deformation. This research explains the new phenomena of land subsidence to a certain degree, but could not identify the mechanism. The authors proposed two approaches to try and identify the load-transferring mechanism by considering the temporal and spatial redistribution of stress due to the withdrawal of groundwater. Firstly, a land subsidence model was established based on the Cosserat continuum mechanism. This model considers shear forces on an aquifer caused by groundwater pumping and hydraulic gradients. Secondly, the internal erosion of ifne particles in the aquifer, which leads to the redistribution of land subsidence in both space and time, was considered. Such land subsidence due to the internal erosion of ifne silty and clay particles in the pores of aquifer should be investigated.