A case study of vacuum tube-well dewatering technology for improving deep soft soil in Yangtze River floodplain

Abstract

Deep soft soil of the Yangtze River floodplain in Nanjing has a special interlayer structure, which provides favorable conditions for the application of vacuum tube-well dewatering technology. This paper focuses on the design, construction and treatment effect of vacuum tube-well dewatering technology. The hydrological parameters and the hydraulic connections between the various layers of the site have been ascertained through two simple single-well multi-holes pumping tests. Moreover, the layout of vacuum tube-wells and depressurization wells in a test site with 84m length and 84m width was designed based on the above parameters. Field tests of vacuum tube-well dewatering technology were conducted on the test site. And the changes of groundwater level, ground settlement and pore water pressure during the test was monitored. The CPTU test technology was used to quickly evaluate the engineering properties of the site before and after treatment. Finally, combined with the settlement monitoring data, the hyperbolic method was used to predict the final settlement. The results indicated that consolidation efficiency of vacuum tube-well dewatering technology has obvious advantages. Implications of this study can provide a reference for the construction design of the site's ground improvement consolidation and other similar projects.

Development of Vacuum Tube Well Dewatering Test Device and Study on Vacuum Degree Transfer Law

“…According to field studies, Bao [21] discovered that the soil's self-weight deposition law had some bearing on the properties of soil's negative pressure transfer at various depths, and negative pressure attenuation was negatively correlated with coarse particle content at depth. Through the field test of vacuum tube well dewatering, Zeng [22] and Li [23] found that the consolidation effect of vacuum tube well dewatering technology is remarkable, and they described the change law of vacuum degree in the soil layer. The majority of researchers agree that there is an attenuation of the vertical transmission of vacuum degree in the soil, but the shape of the attenuation is characterized variably.…”