Vacuum preloading with plastic vertical drains has been applied widely to accelerating consolidation of dredger fills. As a result of nonlinear variations in permeability and compression during the process of dredger fill consolidation, an axisymmetric consolidation method for dredger fill treatment using PVD with vacuum is proposed with varied R_u. The effects of C_c/C_k and the loading ratio on the proposed method are discussed. It is found that the difference between the traditional method and proposed method is obvious in the case of large loading ratio (such as dredger fill treated with vacuum preloading). The degree of consolidation in the early phase of consolidation obtained using the proposed method was less than that obtained using the traditional method and the degree of consolidation in the later phase of consolidation obtained using the modified expression was larger than that obtained using the traditional method, as C_c/C_k < 1. However, opposite trends were observed when C_c/C_k > 1, the proposed method was closer to the actual situation. The applicability of the proposed method was verified by laboratory and field tests. For the consolidation of dredger fill with high water content, we recommend the adoption of the proposed method for calculating the degree of consolidation.

In this study, 12 groups of plane strain model tests of gridded hard crust with different cement contents and structures were conducted with a transparent soil experimental technique. The destruction mode and influence factors in the ultimate state were investigated by analyzing the law of soil displacement and ultimate load change around the structure. The test results revealed that the destruction mode of gridded hard crust under 8% cement content was mainly the destruction of the upper hard crust. Under the condition of small spacing, the grid structure was destructed when the thickness of the hard crust increased. The destruction mode of the gridded hard crust was majorly the destruction of the lower grid structure when the cement content was 15%, and the thinner hard crust was destroyed when the space between grid structures enlarged.