Model tests of consolidation of clay slurry using horizontal drains

• Main Author: Liu, Yixian
• Other Authors: Chu Jian
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Environmental engineering
• Online Access: http://hdl.handle.net/10356/71414
• Institution: Nanyang Technological University

One of the widely used ground improvement approach is vacuum preloading with vertical drains. However, when this method is adopted for land reclamation using soft fill materials, it has limitations because it is difficult to install vertical drains over very soft deposits. To overcome this problem, a new land reclamation method using Prefabricated Horizontal Drains (PHD) has been developed. The objective of this project is to carry out large scale model tests to evaluate the performance of this proposed method. Two model tests were carried out to evaluate the rate of consolidation by vacuum preloading with PHDs and the effectiveness of this method. For each model, 1.5 m3 of marine clay slurry was used. The initial water contents of clay slurry were 140% and 146%. In the first model test, only one PHD was installed at the centre height of tank. In the second model tests, 3 PHDs were used with one located at the central bottom and other two at 2/3 of height from bottom. In both tests, vacuum preloading was applied through the PHDs to consolidate the marine clay. Surface settlements and pore-water pressured in the soil were measured. Asaoka method was used to estimate the ultimate settlement and the average of soil consolidation. The result to display the water content is reduced and the time-dependent of undrained shear strength is raised. The comparing tests show that the rate of settlement for the 2nd model test is much greater than that for the 1st model test. This is indicative that the PHDs were effective in accelerate the rate of consolidation.