A study on evaluation method of the waterproofing system for underground structure applied on earth retaining walls prior to concrete casting

This paper reports the evaluation method of the waterproofing system for underground structure applied on earth retaining walls prior to concrete casting. We examined two tests, the first test is water leak test by using semi-full sized specimen with actual components, and the second test is water leak test by using small sized specimen with the weakness points of this waterproofing system. As a result of the first test, separators and damaged parts are the weakness points of watertightness of this waterproofing system. For the second test, there is deference of watertightness of the specimen between vertical casting concrete and horizontal casting. When the concrete is casted vertically, there will be made air space under separators or rough composition of concrete near waterproofing layer and the water from outside will infiltrate easily if it penetrate through waterproofing layer. So it is necessary for the evaluation method of this waterproofing system to make specimen made of vertical casting concrete.