JZUS - Journal of Zhejiang University SCIENCE

Journal of Zhejiang University SCIENCE A 2021 Vol.22 No.2 P.147-164

http://doi.org/10.1631/jzus.A2000133

Consolidation behavior of Tianjin dredged clay using two air-booster vacuum preloading methods

Author(s): Hua-yang Lei, Yao Hu, Jing-jin Liu, Xu Liu, Chen-yuan Li
Affiliation(s): Department of Civil Engineering, Tianjin University, Tianjin 300350, China; more
Corresponding email(s): liujingjinljj@163.com
Key Words: Tianjin dredged clay, Prefabricated vertical drain air-booster vacuum preloading (PAVP), Tube air-booster vacuum preloading (TAVP), Model test, Microstructure test

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Abstract: This paper presents model tests (macro aspect) and microstructure tests (micro aspect) for investigating the consolidation behavior of tianjin dredged clay using the prefabricated vertical drain air-booster vacuum preloading (PAVP) and tube air-booster vacuum preloading (TAVP) methods. The mechanism of air-booster vacuum preloading (AVP) using a spring-like system is explained. The main difference between these two methods is the air-boosting equipment. A new anticlogging air-booster prefabricated vertical drain (PVD) is used in the PAVP technique and a self-designed air-booster tube is used in the TAVP technique. In the model tests, a comparison of the variables that are monitored during reinforcement (vacuum pressure, surface settlement, water discharge, and pore-water pressure) and after reinforcement (water content, dry density, and vane shear strength) is conducted. The results indicate that the consolidation behavior of tianjin dredged clay using the PAVP method is better than that using the TAVP method. PAVP more efficiently mitigates the issue of water-draining PVD clogging and significantly accelerates drainage consolidation. In addition, in the microstructure tests, a comparison of the variables that are monitored after reinforcement (via scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP)) is conducted, and the results further explain the model test results.

两种增压式真空预压加固天津吹填粘土试验研究

目的:增压式真空预压是加固吹填软土的有效方法,目前主要有排水板注气和增压管注气两种.本文旨在对比分析两种方式的加固效果(真空度、排水量、固结度、剪切强度和微观结构特征等),选出最优加固方法,以期指导工程实践.
创新点:1. 通过模型试验,从宏观角度对比评估两种增压式真空预压的加固效果;2. 通过微观结构试验,从微观角度进一步评估加固效果;3. 分析排水板-增压式真空预压加固效果优于注气管-增压式真空预压的原因.
方法:1. 通过模型试验分析,对比分析两种方法的加固效果(真空度、排水量、固结度、剪切强度和微观结构特征等);2. 通过微观结构试验(扫描电镜和压汞)分析,验证模型试验的结果,并进一步对比排水板-增压式真空预压和注气管-增压式真空预压的加固效果.
结论:1. 在模型试验中,相对于注气管-增压式真空预压,排水板-增压式真空预压的排水量、固结沉降和孔压消散更大,而含水量、剪切强度和固结度更小;2. 在微观结构试验中,排水板-增压式真空预压加固后的土体骨架颗粒形态更均匀密实,孔隙更小;3. 排水板-增压式真空预压的加固效果优于注气管-增压式真空预压.
关键词：天津吹填粘土;排水板-增压式真空预压;注气管-增压式真空预压;模型试验;微观试验

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