Experimental Study on Soil Conditioning of Shield Construction in Hardplastic Highviscosity Layer

Abstract:

A series of soil conditioning laboratory tests with three types of additives were performed to investigate and assess the conditioned effect of hardplastic highviscosity soil in Shanghai ⑥ layer, and analyze the optimal injection rate ranges synthetically. It is shown that the optimum foam injection ratio is 30.0% under 30.0% moisture content (MC). While the optimum injection ratios of polymer and detackifier are 6.0% and 5.5% respectively under the same MC. Moreover, the optimum injection ratios of combination materials with polymer and foam are 3% (polymer) and 20% (foam) respectively, and the optimum injection ratio of combination materials with detackifier and foam are 3% for detackifier and 15% for foam respectively. Succeeding field tests show that the optimum injection ratios of additives significantly improve the performance of earth pressure balanced (EPB) excavation and can be used as guidelines under such soil conditions.