基于分布式精细化监测的抽水区地层变形演化规律及定量评价

The occurrence, development and disaster process of land subsidence caused by excessive groundwater pumping are slow and not easy to detect, which rises the difficulty of subsidence control and treatment. More seriously, land subsidence has become one of the five major geological problems at the moment in China. The monitoring depth and monitoring accuracy of the traditional point-based monitoring technology cannot meet the requirements of precise detection and process monitoring of deep strata deformation, which has restricted the breakthrough in land subsidence mechanism and prediction. This project takes the strata in pumping-induced land subsidence area as the research object. Model test and in-situ monitoring are carried out. Based on the fiber sensing technology, the spatial and temporal variation of the strata deformation are obtain precisely during subsidence, which realizes the accurate location of the main subsidence layer and grasp of the strata deformation evolution rules. On this basis, combined with the soil microstructure change during subsidence, the relationship between soil pore structure and macroscopic deformation is established, and the quantitative evaluation method of strata subsidence potential is proposed. The research results have important significance for the interpretation of land subsidence evolution and disaster mechanism, and it provides a basis for prediction and evaluation of subsidence development trend.

过量抽取地下水导致的地面沉降发生、发展和孕灾过程缓慢而不易察觉，导致沉降控制与治理难度上升，已成为我国当前城市发展面临的5大地质问题之一。传统点式监测技术的监测深度和监测精度远不能满足地面沉降区深部地层变形的精细探测和过程监测要求，制约了地面沉降机理研究和预测评价取得突破性进展。本项目以抽水型地面沉降区地层为研究对象，开展室内模型试验及原位钻孔监测，利用光纤感测技术分布式地获取沉降过程中地层变形沿钻孔全断面的分布信息及随时间的变化规律，实现主要沉降层的精准定位，掌握地层变形演化规律；在此基础上，结合沉降过程中土体细微观结构变化，建立土体孔隙结构与实测宏观变形之间的关系，提出地层沉降潜力定量评价方法。研究成果对掌握地面沉降孕育演化与致灾机理具有重要意义，可为沉降发展趋势的预测评价提供依据。

本项目紧紧围绕“基于分布式精细化监测的抽水区地层变形演化规律及定量评价”这一中心课题，以抽水型地面沉降区地层变形为监测对象，开展了地层沉降变形机理和评价方法研究。采用相似材料物理模型试验、现场原位监测和理论分析相结合的方法，深入探讨了抽灌地下水过程中地层的时空变形演化规律与沉降预测方法，为地面沉降机理研究和定量评价提供了新的思路和方法。项目取得了一批创新成果：（1）实现了土体应变场-水分场分布式信息的获取，掌握了抽灌水过程中土层变形响应规律及水-土耦合机制；（2）完善并应用了地面沉降钻孔全断面精细化监测系统，精细化获取了江苏苏州、天津滨海新区等地地面沉降时空演化特征；（3）建立了宏观土体变形与微观孔隙变化之间的联系，揭示了地面沉降土体结构变化细微观机理；（4）提出了地面沉降潜力定量评价方法，有效评价了各地层沉降潜力，判断了沉降区沉降趋势。本项目的研究实现了抽水区地层从细观变形到宏观灾变的分布式感测和沉降发展的定量评价，为地面沉降的精准防治和地表环境的安全评估及抽灌地下水控制标准的制定提供了参考依据和技术支撑，相关研究成果具有良好的应用推广价值。