Applicability of construction dewatering techniques for randomly-fractured rock

Through analyzing a significant number of case histories, ranges of applications of dewatering techniques for randomly-fractured rock are proposed in terms of the rock mass permeability and the required drawdown. The analyzed cases, which cover a wide range of construction activities and associated dewatering depths, provide one of the most comprehensive studies of dewatering techniques on randomly-fractured rock to date. Comparison of the ranges suggested for dewatering in fractured rocks with those developed for excavations in soils is presented. To fit the construction dewatering systems in rock, a modification is proposed for the drawdown diagram widely used in practice for soils, and for the limited available general recommendations presented for chalk. Consequently, recommendations are made to improve the procedure of designing and executing these systems. In addition, a dewatering technique, which allows for construction to proceed in a wet condition, is proposed taking into account rock shear strength and the excavation geometry.