Experimental study on a dredged fill ground improved by a two-stage vacuum preloading method |
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Authors: | Jun Wang Yuanqiang Cai Hongtao Fu Xiuqing Hu Ying Cai Haizhi Lin Wei Zheng |
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Affiliation: | 1. College of Architecture and Civil Engineering, Wenzhou University, Chashan University Town, Wenzhou, Zhejiang 325035, China;2. Key Laboratory of Engineering and Technology for Soft Soil Foundation and Tideland Reclamation, Wenzhou University, Wenzhou, Zhejiang 325035, China;3. Innovation Center of Tideland Reclamation and Ecological Protection, Wenzhou University, Wenzhou, Zhejiang 325035, China;4. College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China;5. Reclamation Construction and Development Limited Company of Dongtou Zhuangyuan South, Wenzhou, Zhejiang 325035, China;6. Department of Civil and Environment Engineering, Harbin Institute of Technology, Shenzhen Graduate School, Shenzhen 518055, China |
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Abstract: | The vacuum preloading method has been wisely chosen among many ground-improvement methods considering the time limit of many projects and the characteristics of reclaimed soil. However, the loss in vacuum with soil depth, the clogging around prefabricated vertical drains (PVDs), and the deteriorative consolidation of the deep soil layer, among other factors, create a large challenge to vacuum preloading for dredged marine clay fill. Thus, this study proposes a two-stage vacuum preloading method and focuses on its feasibility and effectiveness. Contrasting laboratory tests are performed in two identical experimental tanks with dredged marine clay fill from the Wenzhou land reclamation site in China. In one tank, the one-stage vacuum preloading method is used to serve as a baseline for this study. In the other tank, use of the two-stage vacuum preloading method is proposed for consolidation; it comprises two stages. In the first stage, the dredged marine clay fill is conditioned by vacuum preloading using half of the PVDs, where the dissipation of the excess pore water pressure tends to be steady. In the second stage, vacuum preloading is activated using all the PVDs. The results show that a better consolidation effect is achieved with the proposed method in terms of the settlement, vacuum pressure, pore water pressure, water content, vane shear strength, and soil particle microstructure after soil consolidation. |
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Keywords: | Dredged fill Two-stage Vacuum preloading Consolidation effect |
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