天津滨海地区晚新生代地层自然固结与地面沉降研究

发布时间：2018-04-01 09:09

本文选题：晚新生代　切入点：地面沉降　出处：《岩土力学》2014年09期

【摘要】：天津滨海地区地处渤海湾西岸,晚新生代沉积了巨厚的松散沉积物。地下水位下降、地层自然固结、地表载荷的加速增长等复合因素造成了严重的地面沉降。利用在天津滨海新区塘沽地区施工的一眼1 226 m全取芯钻孔,通过原状样品测试分析,系统研究了晚新生代土层的物理力学性质、黏性土固结特征,并结合欠固结黏性土层沉降量计算等方法阐述了土层固结状态空间特征,探讨了土层固结特征与地面沉降的相关关系。结果表明:该地区0~100 m深度土层具有低天然密度、高孔隙比、高含水率、高压缩性等特点,表现出软土的性质,在地表荷载增大的情况下,易发生地面沉降;100~550 m的黏性土大都处于超固结和微超固结状态,主要是由于过去地下水的大量开采造成的;550 m以下的黏性土多为正常固结,局部存在欠固结黏性土夹层。钻孔中存在合计约218 m的欠固结黏性土夹层,这些欠固结黏性土夹层在自重应力下的最终沉降量为1 985 mm,沉降量最大的土层对应于第1、6含水组,分别达614 mm和665 mm,这一沉降过程完成所需时间为数十年甚至上百年。
[Abstract]:The coastal area of Tianjin is located in the west coast of Bohai Bay. The late Cenozoic deposited extremely thick loose sediments.The decrease of groundwater level, the natural consolidation of strata and the accelerated growth of surface load have resulted in serious land subsidence.The physical and mechanical properties and clay consolidation characteristics of the late Cenozoic soil layer were systematically studied by using the 1 226 m full coring borehole constructed in Tanggu area of Binhai New area of Tianjin, and through the test and analysis of the undisturbed samples.Combined with the method of calculating the settlement of underconsolidated clay soil, the spatial characteristics of soil consolidation state are expounded, and the correlation between soil consolidation characteristics and land subsidence is discussed.The results show that the 0 ~ 100m depth soil layer in this area has the characteristics of low natural density, high void ratio, high moisture content and high compressibility.Most of the 100 ~ 550m clay soils prone to ground subsidence are in the state of overconsolidation and micro-overconsolidation, mainly due to the fact that most of the clay soils below 550 m caused by the massive exploitation of groundwater in the past are normally consolidated, and there is an underconsolidated clay intercalation in the local area.A total of 218 m underconsolidated clay intercalation exists in the borehole. The final settlement of these underconsolidated clay intercalations under gravity stress is 1 985 mm, and the soil layer with the largest settlement corresponds to the first water bearing group,It takes several decades or even hundreds of years to complete the settlement process, which reaches 614 mm and 665 mm respectively.
【作者单位】：天津地质矿产研究所;北京大学工学院水资源研究中心;中国地质大学(武汉)环境学院;
【基金】：中国地质调查局项目(No.1212011120170,No.1212011120089)资助
【分类号】：TU432

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