The construction waste generated by underground excavation in coastal cities has the characteristics of high fine content

high water content and looseness. Landfilling is the most common method for disposal of such construction waste. As the waste production exceeds the capacity of disposal

many of the construction waste dumps have the problems of fast filling

lack of drainage facilities

overload of landfill capacity and over height

which are likely to cause safety accidents such as landslide. These irregulated operations reflect the poor understanding of the strength growth law of the high saturation degree waste during rapid landfilling. In this paper

completely decomposed granite (CDG) waste is taken from the site of Shenzhen Hong’ao landslide

and a series of triaxial tests with the drain and exhaust valves closed is performed on the samples with different initial saturations. The experimental results reveal that the undrained shear strength of CDG nonlinearly increases with the increase of confining pressure

and the growth rate is closely related to the initial saturation of the sample. The growth rate of the undrained shear strength significantly decreases as the saturation exceeds 0.7. Inspired by the principle of undrained strength analysis

an estimation method for undrained shear strength is proposed

in which Hilf’s equation and the modified Cam-clay model are employed. The proposed method is verified to be capable for predicting the undrained shear strength for CDG with an initial saturation exceeding 0.6 by comparing the estimation results with the measured values in the triaxial tests. The undrained shear strength cu and normal stress determined by the estimation method can be used in the stability analysis of waste dump with high filling rate.