Study of the strength characteristics of dredger fill under the combined action of impact load and drainage

Abstract

This paper studied the strength growth characteristics of Tianjin Binhai dredger fill, considering the impact load, drainage condition, and loading way of the impact. Based on UU and scanning electron microscope tests, the strength growth mechanism of the dredger fill was studied from both macroscopic and microscopic perspectives. The results showed that there an optimal impact load under the combined action of impact load and drainage, which can enhance the strength of the dredger fill to the maximum extent, its value is close to the structural yield stress. Furthermore, the methods of ‘more impact rounds and fewer impact counts’ and ‘first light then heavy’ can obtain the best effect of foundation reinforcement. Microstructural analysis showed that, with the increase in impact loads, the pore complexity and the number of pores increased, while the porosity, the number of soil particles, the pore circumference, and the total pore area decreased. This research also showed that the increase in the strength of dredger fill was mainly reflected by the increase in the internal friction angle under the combined actions of impact load and drainage, while the change of cohesion was rather small. The mathematical relationship between the internal friction angle and the pore characteristic can be expressed by a unary function, which increases with increasing pore complexity.