基層材料對複合阻水層效能之影響

Abstract

由於地工合成材料品質穩定且施工簡易，在歐美國家已廣泛使用於廢棄物掩埋場中。 本研究探討以GCL及GM組成的複合阻水層在發生破洞的時候，其上水頭高度、垂直載重大小，以及其下介面平整與否對滲流的影響。使用特殊設計的滲透儀求得複合阻水層的滲透性，試驗結束後量測試體厚度與基重的變化量，進而了解皂土受擠壓的變化情形。 實驗結果顯示隨著有效應力的增大，複合阻水層可能被尖銳的基層材料刺穿；除了此種情形之外，複合阻水層的阻水性隨有效應力的增大而增加。基層材料的平整度越佳，滲流率變化幅度越緩；GCL的厚度與基重變化，都與滲流率的變化有相同的趨勢

Geosynthetics were widely used in landfills, espcially in the United States and European countries. The objective of this research is to study the effect of subgrade condition on the performance of geosynthetic composite liner composed of geomembrane (GM) and geosynthetic clay liner (GCL). Laboratory permeation tests were performed to measure the flowrate of water through the composite liner with holes in the GM. After each test, the thickness and mass per unit area of the GCL specimen was measured in a number of locations to determine the variation of distribution of bentonite. The results show that the flow rate through the composite liner decrease with increasing confining stress in general. However, there were two instances where the GCL specimens got punched by the crushed-stone subgrade, such that the flowrate was significantly higher. Furthermore, it was found that the distribution of bentonite was more uniform for GCLs in contact with subgrade of smaller size particles.