Case Study on Deformation Control of Upper-Soft and Lower-Hard Large Span Tunnel Station using Combined Control Technology and Monitoring Demonstration

Abstract

A large number of shallow buried tunnels are built in the city nowadays and the special strata such as large upper-soft and lower-hard ground often encountered. Deformation control of strata is the focus issue related to the construction safety. Based on Dalian metro Hing Street station with the classical geological condition of upper-soft and lower-hard ground, this paper fully used a combined control method including six different support measures to control the deformation of surrounding rock. 3D finite element model was setup to analyze the construction effect of combined control measures and the monitoring in-site was carried out to verify the deformation control effect of combined control method. It shows that the maximum surface subsidence value is gradually reduced with the support measures gradually increasing. In the case of various supports the maximum sedimentation value is 2.67 cm, which is 42. 1% lower than that of not using control method and the control effect is obvious. In addition, it can be seen that the two-layer initial support and additional large arch foot have the best effect on controlling the ground surface settlement with reduction of 11.7% and 20.2%, respectively. The research results can provide practical experience for the construction of such tunnels, and guide the design and construction of the tunnel in the future.

Field Monitoring of the Deformation and Internal Forces of the Surrounding Rock and Support Structures in the Construction of a Super-Span High-Speed Railway Tunnel—A Case Study

“…4 The critical time point at which the displacement increment between two adjacent monitoring points started to change suddenly (Time Point 4). 5 The time point when the displacement of each monitoring point began to converge (Time Point 5). 6 The cut-off time of the monitoring (Time Point 6).…”

“…As the country's economy had developed, the construction of tunnels in China has entered an era of rapid development [1,2]. More and more super-span tunnels have been proposed in the fields of water conservancy, transportation and municipal engineering [3][4][5]. Table 1 has shown a few typical super-span tunnel examples that have been constructed in China in recent years.…”

A Novel Method for Analyzing the Factors Influencing Ground Settlement during Shield Tunnel Construction in Upper-Soft and Lower-Hard Fissured Rock Strata considering the Coupled Hydromechanical Properties

“…Yang et al [4] studied the influence of the surrounding rock stability of tunnel boring machine (TBM) tunnel construction in upper-soft and lower-hard strata through physical experiments and numerical simulations (NSs) and analyzed the evolution trends and distribution characteristics of the stress, displacement, and failure. Shang et al [5] used a finite element model to study the deformation trends of the surrounding rock in subway stations with different support forms in the upper-soft and lower-hard strata. The ground settlement was shown to be greatly affected by the large-span arch of the primary support structure.…”

Distribution Features of the Minimum Rock Cover Thickness of the Surrounding Rock Self‐Stability of the Metro Tunnel in the Soil‐Rock Dualistic Stratum

“…e fundamental goal of an excellent metro tunnel design scheme is to make full use of the self-stability of the surrounding rock. Recently, many subsurface metro tunnels have been carried out in the soil-rock dualistic stratum in cities, such as Qingdao [1], Dalian [2], Guangzhou [3], Chongqing [4], and Guiyang [5]. When a metro tunnel is excavated in the urban area where the buried depth of the bedrock is shallow and the soft soil stratum thickness is thin, the tunnel should be placed in the rock stratum and maintained such that the minimum rock cover thickness meets the requirements of the self-stability of the rock surrounding.…”