Use of X-Ray Radiographic Techniques in the Evaluation of Soil Liners.

摘要

In this preliminary study to determine the usefulness of soil X-ray radiographic techniques and radio-opaque permeants in testing compacted clay liners used for waste containment two methods were examined: one method involved intermittent examination of a test cell during permeation; a second method involved preparing X-radiographs of whole or sliced specimens of simulated liners after they had been subjected to permeater testing. X-radiographs taken during permeation of a bentonite/sand liner permitted documentation of the progressive invasion of the liner and the development of changes in liner structure (formation of channels or voids). A radio-opaque permeant (Pb(NO3)2) proved useful for following liquid movement but was not necessary if only structural changes in the liner were being investigated. X-radiographs prepared from whole or sliced samples of simulated liners after permeability testing provided data on: the homogeneity of the sample, production of open flow paths in the sample, uneven infiltration of the permeating liquid, and the occurrence of surface plugging from suspended solids and side wall leakage. Precipitates forming in the liner could also be observed. The X-ray technique was evaluated with four different types of compacted clay soil liners and five permeating liquids--three aqueous solutions and two suspensions in organic solvents. The radio-opaque compounds used as tracers were Pb(NO3)2, Pb(C2H3O2)2, and Pb3O4. Keywords: Landfill.