Abstract
Water inrush caused by the wetting-drying cycle is a difficult problem in tunnel excavation. To investigate the effect of the wetting-drying cycle on the stability of the tunnel surrounding rock, physical experiments and numerical simulations regarding the process of tunnel excavation with different wetting-drying cycle numbers were performed in this study. The evolutions of stress, displacement, and pore water pressure were analyzed. With the increase in cycle number, the pore water pressure, vertical stress, and top-bottom approach of the tunnel surrounding rock increase gradually. And the increasing process could be divided into three stages: slightly increasing stage, slowly increasing stage, and sharply increasing stage, respectively. The failure process of the surrounding rock under the wetting-drying cycle gradually occurs from the roof to side wall, while the baseplate changes slightly. The simulation results showed that the maximum principal stress in the surrounding rock mass of the tunnel increases, while the minimum principal stress decreases. Furthermore, the displacement of the rock mass decreases gradually with the increasing distance from the tunnel surface. By comparing the simulation results with the experimental results, well consistency is shown. The results in this study can provide helpful references for the safe excavation and scientific design of a tunnel under the wetting-drying cycle.
Highlights
With the development of tunnel projects to mountainous terrain, the effect of the wetting-drying cycle on the surrounding rock mass has aroused the concern of many scholars
In order to solve these special engineering problems, many researchers performed many laboratory tests to study the effect of the wetting-drying cycle on the physical and mechanical properties of the rock mass, especially strength and deformation [8,9,10,11]
Coombers and Naylor [13] investigated the weathering mechanism of limestone, granite, concrete, and other materials with different wetting-drying cycle numbers through the scanning electron microscope (SEM)
Summary
With the development of tunnel projects to mountainous terrain, the effect of the wetting-drying cycle on the surrounding rock mass has aroused the concern of many scholars. In order to solve these special engineering problems, many researchers performed many laboratory tests to study the effect of the wetting-drying cycle on the physical and mechanical properties of the rock mass, especially strength and deformation [8,9,10,11]. Li et al [15] investigated the influence of water content on the strength and deformation properties of metasandstone specimens through the triaxial compressive tests. Some model experiments and numerical simulations were conducted to study the overall stability of the tunnel surrounding rock under the effect of the wettingdrying cycle [16,17,18]. Few geomechanical model tests were carried out to study the instability failure behavior and water inrush of the tunnel surrounding rock under the effect of the wetting-drying cycle. The principal stress distributions and deformation characteristics under the wetting-drying cycle are further revealed, providing a theoretical basis for the prevention and control of water inrush in underground engineering
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