In the vacuum treatment of dredged slurries via prefabricated vertical drains (PVDs), both filtration and consolidation may happen to dredged slurries when subjected to the vacuum gradient. Similar to the consolidation, the filtration may provide equally useful information on interpreting the constitutive behavior of the slurry. In this paper, a new approach utilizing the filtration process is devised to evaluate the constitutive behaviors of dredged slurries. The approach is composed of a vacuum filtration device and an iterative curve fitting algorithm. Two types of tests, namely step-vacuum filtration and constant-vacuum filtration followed by compression test, must be conducted on the slurry specimens, and only the time variations of the filtrate discharge should be recorded. On the basis of the recorded data, the curve fitting algorithm is adopted for determining the parameters of the constitutive equations. The effectiveness of the proposed approach is verified through comparing the obtained compressibility and permeability of the slurries with the data provided by the oedometer test and with the empirical relationships from different sources. The comparisons demonstrate that the constitutive relationships determined by the present approach can predict the compressibility and permeability characteristics of dredged slurries with an acceptable degree of accuracy.

Using the foundation pit at the Jianye Road Station of Hangzhou Metro Line 6 as a case study, the deformation characteristics of a foundation pit subjected to asymmetric loads is investigated in this paper using PLAXIS 3D numerical simulation software. The influence of active pressure zone reinforcement, passive pressure zone reinforcement, and increased thickness of the diaphragm wall at the loaded side on the maximum lateral displacement of diaphragm wall retaining structure of foundation pit is also systematically analyzed. The results show that the deformation of the diaphragm walls on both sides of the foundation pit is strongly inconsistent when subjected to asymmetric loads and is affected by the asymmetric load value and its distance to the foundation pit. In order to reduce the lateral deformations of foundation pit subjected to asymmetric load, two displacement control methods are adopted in the numerical simulations. It is shown that reinforcing the active pressure zone can reduce the maximum lateral displacement of the diaphragm wall on the loaded side to a certain extent but the reinforcement should have a certain depth, resulting in poor efficiency. On the other hand, reinforcing the passive pressure zone can effectively reduce the difference in lateral deformation between the two sides of the foundation pit by increasing the depth and width of the reinforcement zones. It is also observed that the increase in the thickness of the diaphragm wall can reduce the adverse effect of asymmetric loads on the foundation pit. The research results can provide reference for using measures to reduce the influence of asymmetric loads.