In case of underground construction affected by groundwater, CIP (Cast-In-Place Pile) method is generally used to resolve the geo-hydraulic problem. However, as this method has poor connectivity between piles, an auxiliary method for cut-off is needed in many cases. In this study, a new concept earth retaining wall method (H-CIP) with no auxiliary method, by using surfactant grout (Hi-FA) which improves antiwashout and infiltration ability, is introduced, and its field applicability is evaluated. CIP and H-CIP piles were installed with same ground conditions, and field permeability tests were conducted to verify the performance. As results, newly contrived H-CIP method shows higher antiwashout performance for cut-off than conventional CIP method.

The purpose of this paper is to improve the method for rear cavity inspection of cut-off wall at concrete faced rock-fill dam. To do this, we suggested that using impact echo wave, analysis of embeded instruments data, and numerical method to considering the expecting crack open failure behavior. We hope that improved methods were assist maintenance of concrete cut-off wall at concrete faced rock-fill dam.