地面沉降钻孔全断面光纤多参量精细化监测——以杭州萧山区山末址村为例

Full section multi-parameter precise monitoring of fiber optic in land subsidence borehole:a case study of Shanmozhi Village,Xiaoshan District of Hangzhou

为了科学防控地面沉降,文章以杭州萧山区山末址村地面沉降重点区为研究对象,在系统分析其地面沉降成因机理的基础上,建立了钻孔全断面光纤多参量地面沉降自动化监测示范点,识别了不同深度土层的沉降变化特征和主要沉降层位,探究了弱透水层与含水砂层在不同水位变化模式下的变形特征。结果表明:①示范点处当前主要沉降层位集中在第二弱透水层和第I2承压含水层,平均沉降量占比分别为29.59%和33.21%,且有增大的趋势;②监测期内随着地下水位的持续回升,第I2承压含水层主要表现为弹性变形,且存在较小的残余变形;③第二弱透水层变形明显滞后于孔隙水压力的变化,具有塑性变形和蠕变的特点。实践表明,建立的监测示范点能够准确获取地面沉降发育过程中高精度的多参量数据,可为地面沉降的机理研究和模型预测提供数据支撑。

In order to scientifically prevent and control land subsidence,taking the key area of land subsi-dence in shanmozi village,Xiaoshan District,Hangzhou as the research object,based on the systematic analysis of the mechanism of the local land subsidence,a demonstration site for automatic monitoring of land subsidence with multi-parameter optical fiber in full cross section of borehole was established.And the variation characteristics of subsidence at different soil depths and the primary subsidence layers were identified,and the deformation charac-teristics of aquitard and sand aquifer were explored under the different modes of water level changes.The results show that the current primary subsidence layers at the demonstration site are concentrated in the second aquitard and the I2 confined aquifer,and the average subsidence accounts for 29.59%and 33.21%respectively,and show-ing an increasing trend.Moreover,during the monitoring period,the I2 confined aquifer mainly shows elastic de-formation,and there is small residual deformation with the continuous rise of groundwater level.The deformation of the second aquitard obviously lags behind the change of pore water pressure,and has the characteristics of plas-tic deformation and creep.The practice shows that the established monitoring demonstration site could accurately obtain high-precision,multi parameter data in the process of land subsidence,and provide data support for study of land subsidence mechanism and model prediction.