Hydraulic Conductivity of Various Cut-off Walls by In-situ Tests

Abstract

In the construction planning of cut-off wall, hydraulic conductivity (k) is a crucial parameter. There are various construction methods for cut-off walls, and the effectiveness is compared by k listed in the technical documentation for each method to select the most suitable method. However, these k lack clarity regarding construction conditions, ground conditions and evaluation methods, and there are very few cases where different methods have been compared at the same site. Additionally, when construction space is limited, methods are restricted to those using small machinery such as steel sheet piles, jet grouting and chemical grouting. Therefore, we constructed cut-off walls using these methods in the same ground conditions and evaluated their k. As a result, we found that some methods showed higher values than those in technical documents, some showed lower values, and some methods showed different values between in-situ tests and laboratory tests. Consequently, it is necessary to consider safety factors for k in technical documents, and field verification is deemed necessary.