Soil deformation control is the key to shaft support. To better control soil deformation, improve construction efficiency, and reduce pollution, this study proposed a prefabricated prestressed supporting structure. The structure consisted of prefabricated steel structure units and special prestressed components. The structure units were applied to retain the soil. The screws were used for prestressing. Field prototype tests were conducted to assess the support effects and analyze the stress and deformation behaviors of the shaft. The earth pressure, the stress in the structure unit, and the lateral displacement of the soil were monitored. The measured earth pressure varied between the earth pressure at rest and the passive earth pressure. The stress of the supporting structure was far less than the yield strength of steel. Changes in the earth pressure and structural stress can be divided into four stages: rapid attenuation, fluctuation, slow change, and stabilization. Both the earth pressure and the structure stress completed the major attenuation within three days of prestressing. The surrounding soil moved out from the shaft under prestress conditions and exhibited an obvious space-time effect. The study of stress and deformation provides guidance for the construction of newly prefabricated prestressed structures.

Due to the increasing depths of underground urban construction, the surrounding environment and hydrogeological conditions are becoming increasingly complex, and conventional high-pressure rotary jet grouting has become unable to meet construction needs. At present, Rodin jet pile (RJP) ultra-high-pressure rotary jet grouting has been widely used as a grouting reinforcement method for deep and large foundations in silty soils, fine sands and clay strata; however, there have been no successful applications in a sandy gravel stratum with high water content (namely, water-rich sandy gravel stratum). Therefore, this paper uses the ventilating shaft in a section of the Beijing Metro as the construction background to carry out field tests on the RJP ultra-high-pressure rotary jet grouting method and waterstop in a water-rich sandy gravel stratum. Through a series of experiments monitoring the formation deformation and pore water pressure and exposing the pile diameter, pile occlusion, pile strength, and permeability of the test pile construction process, it is believed that, for the RJP ultra-high-pressure construction method in a water-rich sandy gravel stratum, reliable jet solidification can occur, the joint between jets can be achieved, the solid strength can reach 10 MPa or higher, and the permeability coefficient can reach 10⁻⁸ cm/s. Therefore, RJP ultra-high-pressure rotary jet grouting can be applied as a waterstop method in water-rich sandy gravel stratum.