利用直接推进技术测定渗透系数的最新进展

高精度测定渗透系数（K）的重要性不言自明，但是现阶段野外试验手段能够提供的关于K的信息不能满足高度非均质地层中污染物迁移预测模拟的需求。直接推进注入记录器(Direct Push Injection Logger, DPIL)和直接推进渗透仪(Direct Push Permeameter, DPP)是新发展的水文地质参数测量仪器，能够使K值的测定达到前所未有的分辨率和成本效益水平。工具向地下推进过程中，通过对注水量、注水压力和其它的水文地球物理参数的同步监测，直接推进技术(Direct Push, DP)能快捷准确地获得地层渗透系数的垂向分布。DP技术几乎适用于所有野外松散地层，并且对场地的干扰很小。因此，它克服了许多基于既有井的传统含水层测试方法的局限性。最近在美国MADE试验场的一个案例研究表明，使用DPIL/DPP可以获得空间分辨率达15cm的K值垂向分布。未来，高精度直接推进技术还可以与新一代的地球物理技术，例如高精度探地雷达相结合，以实现不同位置DP测定K值的互联以及整个试验场K值三维分布的确定。

A review of recent developments in using direct-push technologies for rapid,high-resolution hydraulic conductivity measurements

Despite the clear importance of high-resolution hydraulic conductivity estimates,the current generation of field methods is not capable of providing such information at the level of detail required for predictive transport modeling in highly heterogeneous formations.Direct-push injection logger(DPIL) and direct-push permeameter(DPP) are a new generation of novel site characterization tools that hold much promise for hydraulic conductivity measurements at a level of resolution and cost-effectiveness that has not previously been possible.By monitoring injection flow rates,hydraulic pressures and potentially other hydrogeophysical parameters during tool advancement,direct push(DP) methods provide quick and accurate information about vertical variations of subsurface hydraulic properties.DP methods can be used virtually in any unconsolidated environment and have minimal site disturbance,thus overcoming many of the limitations associated with conventional methods based on existing wells for aquifer testing.A recent case study at the MADE site in the United States shows that with DPIL/DPP tools,it is possible to achieve a spatial resolution of about 1.5 cm in measuring the hydraulic conductivity distribution along vertical profiles.In the future,high-resolution DP tools can be further combined with a new generation of geophysical methods such as high-precision ground penetrating radar(GPR) surveys to interconnect K features identified in the DP profiles and develop a three-dimensional model of the K field across an entire site.