Abstract
Due to its advantages (fast and accurate calculations), the Hyperstatic Reaction Method (HRM) was used to calculate the internal forces of circular tunnel linings in former works. This paper presents an improved HRM method that is developed to estimate the internal forces induced in square and rectangular tunnel linings. Based on the comparison of the internal forces induced in these linings obtained from the HRM method and the finite element method (FEM), the improved HRM method was validated. An extensive parametric analysis of the tunnel lining and ground parameters was then carried out using both the HRM and FEM. The results indicated a great influence of the lateral earth pressure coefficient K0, and the tunnel lining flexibility ratio F on the internal forces induced. Accordingly, the bending moments M, normal forces N, and shear forces T, induced in the tunnel lining decrease when the flexibility ratio of tunnel lining F increases. The maximum bending moment is observed at the tunnel sides that are perpendicular with the larger principal stress direction.
Highlights
Nowadays, circular tunnels are commonly used when mechanized tunnelling is used
The main advantage of the square and rectangular tunnels compared to the circular ones is that they have a greater space utilization ratio
The purpose of this study is to develop the Hyperstatic Reaction Method (HRM) method for the lining design of square and rectangular tunnels
Summary
Circular tunnels are commonly used when mechanized tunnelling is used. The design of circular tunnels was thoroughly studied by many authors [1,2,3,4,5]. The main advantage of the square and rectangular tunnels compared to the circular ones is that they have a greater space utilization ratio. Design methods of these tunnels were developed and could be categorized in analytical methods [1,6,7] and numerical methods [7,8,9,10,11,12,13,14,15,16,17]. The drawback of analytical methods lies in their simplified assumptions They consider that the behaviour of the soil and tunnel lining is isotropic and homogeneous [6,7]. It is interesting to develop free and simple tools that can help users to calculate the internal forces induced in rectangular and/or squared tunnels in a short time
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