一、前言在水文地质勘探工作中,一个抽水试验钻孔往往不只是揭穿和试验一个含水层,而在许多情况下,都需要揭穿和试验两个或两个以上的含水层。为了对这些含水层的含水性进行分别了解,通常是按照试验含水层的顺序,将含水层挨次用套管隔离起来。这样就需要付出很大的人力、物力和时间,尤其当钻孔深度很大,穿过的含水层层数很多时,在施工技术上更显得特别困难,有时简直无法施工。此外,在含水层呈层状结构时(即一个含水层系由数个透水性不同的岩层所组成时),或数个含水层彼此之间有极活跃的水力联系时,想用套管隔离的办法来达到分层了解透水性的目的,也是很困难的。再如 I. INTRODUCTION In hydrogeological exploration, a pumping test borehole often does more than just expose and test an aquifer, but in many cases it is necessary to expose and test two or more aquifers. To understand the water-bearing properties of these aquifers, it is common practice to isolate the aquifer one by one in the order of the aquifer to be tested. This requires a lot of manpower, material and time, especially when the drilling depth is large, through the aquifer layer is very large, the construction technology is even more particularly difficult, and sometimes simply can not be constructed. In addition, casing is required to isolate aquifers when they are layered (ie, when an aquifer consists of several rock formations with different water permeability), or when there are very active hydraulic connections between several aquifers Approach to achieve the purpose of understanding the water permeability, is also very difficult. Another example