Abstract
Geological hazards such as instability of surrounding rock and leakage of water are easily occurred in subway tunnels crossing water rich sand layers. Based on the principle of fluid solid coupling in porous media, this paper studies the plastic zone distribution of surrounding rock and reinforcement ring, vertical settlement of tunnel vault and water seepage of tunnel before and after grouting reinforcement for water rich sand layer. Considering the compressibility of rock mass, the relationship between porosity, permeability and volume strain is further deduced and simplified. A set of numerical calculation formula is set up to study the change of physical parameters of the water rich sand layer before and after grouting to determine the grouting effect and select the thickness of the best grouting reinforcement ring. The results show that the deformation and water permeability of the tunnel decrease with the increase of the thickness of the grouting reinforcement ring. The thickness of the grouting reinforcement ring is the most reasonable when the thickness of the reinforcing ring reaches a certain value, and the thickness of the grouting reinforcement ring is designed to be 5~6m. The research results have been successfully applied in the grouting project of Qingdao Metro stone elderly bathing beach. The reliability of the numerical simulation is verified by comparing the data from the field monitoring and measurement, providing reference for the related projects.
Highlights
With the rapid development of construction, municipal, water conservancy and transportation projects, more and more projects need to be constructed in extremely complex strata, which leads to a large number of underground disaster prevention and control problems, and grouting[1,2,3] reinforcement is a traditional method of underground engineering disaster prevention and control
Li Lu et al.[6] established a fluid solid coupling model describing the diffusion of viscous slurry in porous media.Ye Yuanxin et al.[7] systematically summarized and introduced the coupling characteristics of rock seepage
A large number of scholars have studied the effect of grouting reinforcement ring
Summary
With the rapid development of construction, municipal, water conservancy and transportation projects, more and more projects need to be constructed in extremely complex strata, which leads to a large number of underground disaster prevention and control problems, and grouting[1,2,3] reinforcement is a traditional method of underground engineering disaster prevention and control. A large number of scholars have studied the effect of grouting reinforcement ring. They often simplify the tunnel into a circular section and consider the influence of the lining system on the surrounding rock. It is more practical to consider only the effect of grouting reinforcement ring on surrounding rock. The coupling effect of stress field, displacement field and seepage field should be considered in the study of grouting reinforcement circle. With the help of numerical simulation software, the variation characteristics and interaction of stress field, displacement field and seepage field of surrounding rock before and after grouting are studied, and the influence of thickness and permeability of reinforcement ring on stability of surrounding rock and water inflow of tunnel is further studied. The grouting effect is discussed and the parameter design of reinforcement ring is optimized to provide reference for other similar projects
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