基于DFOS的苏州第四纪沉积层变形及地面沉降监测分析

发布时间：2018-02-26 08:42

  本文关键词： 地下水抽取 地面沉降 第四纪沉积层 分布式光纤监测 压缩度　出处：《工程地质学报》2016年01期 　论文类型：期刊论文

【摘要】：苏州地区广泛分布松散第四纪沉积物,大量抽取地下水导致了苏州大范围的地面沉降,严重影响了该区经济发展。本文在苏州盛泽200m钻孔内安装了分布式感测光纤,采用BOTDR及FBG等分布式光纤感测技术(DFOS),对第四纪沉积层压缩及地面沉降进行了长期的监测分析。分析结果表明:苏州盛泽地区第四纪土层可分为3个含水层(Af)及4个弱透水层(Ad),现阶段含水层压缩已不明显,主要压缩层为与抽水含水层相邻的两个隔水层,且与抽水含水层距离越近的部位压缩越明显;第四纪沉积层的变形与抽水含水层孔隙水压变化基本一致,呈现出夏季压缩,冬季略回弹的趋势,并且存在滞后现象;定义压缩度为各层累计压缩量与其自身厚度的比值,即每米压缩量。各土层沉降趋势可用压缩度判断,对于黏土隔水层沉降程度Ad2Ad3Ad4Ad1,对于含水砂层,Af2为主要变形层,Af1及Af3变形基本稳定。DFOS技术为研究地面沉降机理,评价土层压缩变形潜力提供了十分先进的监测手段。
[Abstract]:The loose Quaternary sediments were widely distributed in Suzhou area, and a large amount of groundwater extraction resulted in a large area of land subsidence in Suzhou, which seriously affected the economic development of the region. In this paper, distributed sensing fiber was installed in the 200 m borehole of Shengze, Suzhou. Using distributed optical fiber sensing techniques, such as BOTDR and FBG, the long-term monitoring and analysis of Quaternary sedimentary layer compression and land subsidence are carried out. The results show that the Quaternary soil layer in Shengze area of Suzhou can be divided into 3 aquifers and 4. At this stage, the compression of the aquifer is not obvious. The main compression layer is the two water-isolated layers adjacent to the pumping aquifer, and the more close to the pumping aquifer, the more obvious the compression is, and the deformation of the Quaternary sedimentary layer is basically consistent with the variation of pore water pressure of the pumping aquifer, showing the summer compression. The tendency of springback in winter is slight, and there is lag phenomenon, the compression degree is defined as the ratio of the accumulative compression amount of each layer to its own thickness, that is, the amount of compression per meter, and the settlement trend of each soil layer can be judged by the compression degree. For the settlement degree Ad2Ad3Ad4Ad1 of the clay barrier, for the main deformed layer (Af1) of the water-bearing sand bed, and for the stable deformation of Af3, it provides a very advanced monitoring method for studying the mechanism of land subsidence and evaluating the compressive deformation potential of the soil layer.
【作者单位】： 南京大学地球科学与工程学院;南京大学地理与海洋科学学院;中国地质调查局南京地质调查中心;
【基金】：国家自然科学基金重点项目(No.41230636);国家自然科学基金项目(No.41372265) 地质矿产调查评价专项(1212011220002)资助
【分类号】：P642.26;P534.63
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本文编号：1537292