截渗工程建设是防治滨海含水层海水入侵的重要措施之一，深入研究滨海地区地下截渗墙作用下海水入侵防治的作用机制和环境效能，对于滨海地下水资源的开发利用和保护具有重要的科学意义和应用价值。本项目针对截渗工程防治海水入侵问题，进行潮汐条件下室内模拟示踪试验和现场尺度的数值模拟，研究截渗墙作用下地下水流速、流向和咸水楔的动态变化特征，揭示地下截渗墙条件下海水入侵-净化的内在作用机制；提出了地下咸水楔回退率、地下水排泄量减少率和残留盐分去除率等评价指标，定量评价截渗墙作用下陆源地下水排泄、海水入侵和上游含水层残留咸水淡化的行为和效能，预测含水层中高浓度和低浓度残留咸水的实际淡化时间，进一步优化地下截渗墙的结构和布局，可以为滨海地区截渗工程建设提供科学的依据。

The construction of subsurface physical barrier is one of the effective countermeasures to control the saltwater intrusion in coastal aquifers. The investigations of control mechanism and environmental effect of seawater intrusion under subsurface dams are of significant scientific and practical values for the protection and utilization of coastal groundwater resources. In terms of the seawater intrusion prevention, a series of indoor experiments and field-scale numerical simulations will be conducted under tidal effect to explore groundwater flow rate, direction and the transient behavior of saltwater wedge and to reveal the dynamic mechanism of seawater intrusion and purification with the installation of subsurface dam. The reduction rate of subsurface discharge, reduction rate of saltwater wedge length and removal rate of trapped salt mass are developed to evaluate the seaward groundwater discharge, seawater intrusion and residual saltwater desalinization. The purification time of high-concentration and low-concentration residual saltwater are predicted, and the structure and arrangement of subsurface dam can be further optimized. Finally, we are able provide a scientific basis for the design and construction of subsurface dam in the coastal areas.