Abstract
This paper presents new correlations for estimating the surrounding rock pressure of symmetrically shaped tunnels based on a symmetrical numerical model. Surrounding rock pressure is defined as the load acting on the support structure due to the deformation of the surrounding rock after tunnel excavation. Surrounding rock pressure is directly related to the selection of the lining structure and the determination of support parameters. The main challenge in designing and proceeding with the construction process is choosing a calculation method for the surrounding rock pressure for super-large sections, and this has been the focus of research among the tunnel research community. The excavation area of Liantang tunnel of Shenzhen Eastern Transit Expressway (China) is over 400 m2, making it the largest highway tunnel in the world so far. Based on this project, this paper analyses the applicability of various traditional methods of calculating the surrounding rock pressure for super-large section tunnels. In addition, based on the Tunneling Quality Index (Q), the factor of span is introduced into the method of calculating the surrounding rock pressure using the numerical simulation results of super-large symmetrical tunnels with different values of Q and different spans. Additionally, calculated correlations that could quickly estimate the surrounding rock pressure of tunnels are obtained. The comparison of surrounding rock pressures between the estimated and monitoring results of Liantang tunnel and more than 30 projects around the world effectively proves the rationality and universal applicability of the proposed correlations. This method could provide engineers and designers with a quick way to predict the surrounding rock pressure of deep super-large section underground structures during their design and construction stage.
Highlights
With the rapid development of the economy, logistics and automobile industry, the traffic flow and comfort standards of highway traffic are significantly improving
This paper analyses the applicability of various traditional methods of calculating the surrounding rock pressure for super-large section tunnels
The results show showthat thatthe thesurrounding surrounding rock pressure values have a certain linear relationship span under different
Summary
With the rapid development of the economy, logistics and automobile industry, the traffic flow and comfort standards of highway traffic are significantly improving. Traditional two-lane and three-lane highway tunnels struggle to meet the needs of modern traffic development. According to the standard recommended by Japan Tunnel Association [1], the tunnel sections can be defined in accordance with Table 1, which means the standard two-lane tunnel section is less than. 100 m2 and the super-large section tunnel is over 140 m2. Up till there are 51 highway tunnels with a maximum area of more than 200 m2 excavated by drilling and blasting methods in China and abroad.
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