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This short communication reports a water inrush hazard during the construction of the Shijingshan Tunnel in Zhuhai, Guangdong, China. On 15 July 2021, a water inrush accident occurred at the construction site 1.16 km away from the tunnel entrance, resulting in 14 casualties. The purpose of this study is to investigate and discuss the water inrush process in this atypical case. The principal causes of this tunneling accident include the special geological conditions at the construction site, high hydraulic conductivity at the part that connects the underground water system and the overlying water body (the Jida Reservoir), and the impact of heavy rainfall. Moreover, four significant suggestions are proposed to prevent the possible occurrence of water inrush disaster: (1) assessing the risk level in areas prone to water inrush; (2) getting a comprehensive geological prediction based on borehole data and artificial intelligent methods; (3) establishing a monitoring system during the tunneling process; (4) strengthening the self-protection skills of construction workers. [ABSTRACT FROM AUTHOR]

In this study, analytical solutions are presented for the axisymmetrical consolidation of an unsaturated soil stratum on the basis of Fredlund and Hasan's one-dimensional consolidation theory. Two different loading conditions, i.e., instantaneous loading and ramp loading, were considered. The derivation process of the proposed analytical solution is simpler in contrast to the existing analytical solutions and it was verified to be accurate using an analytical solution in the literature. In addition to the analytical solutions under the assumption of free strain, the analytical solutions under the assumption of equal strain were further derived. In the parametric study, the variations in the excess pore-water and pore-air pressures as well as the average degree of consolidation are presented. Graphs are given to show the influence of the different hydraulic conductivity ratios between the air and water phases as well as the construction time (under a ramp loading condition) to the consolidation process. These two factors have significant impact on the consolidation of the air phase but little influence on the consolidation process of the water phase. [ABSTRACT FROM AUTHOR]

Surcharge combined with vacuum preloading is a common technique for accelerating the consolidation process in ground improvement. A unit cell model for the axisymmetric consolidation of a soft soil using a prefabricated vertical drain (PVD) under a surcharge, combined with vacuum preloading, is investigated in this study. Based on this model, analytical solutions for a multi-layer soil system are put forward and the explicit expressions for two-layer and one-layer systems are presented. The accuracy of the proposed solution is verified using an analytical solution available in the literature. In the parametric study, the influencing factors on the consolidation process, such as, the smear zone, the PVD spacing, the hydraulic conductivity in the radial direction, the coefficient of vacuum decrease, are taken into account. The water flow in the radial direction plays an important role in the consolidation process while the impact of the vertical flow mainly develops around the interfaces between two adjacent layers. In addition, the proposed analytical solution is applied in a case history with three different layers and the results are reasonable. [ABSTRACT FROM AUTHOR]