Based on Terzaghi's theory on loosening earth pressure, two failure modes of soil upon shallow EPB shield tunnel caused by synchronous grouting are analyzed, and the theoretical equations of synchronous grouting pressure is built to calculate the maximum and minimum grouting pressure which correspond to the limit states of subsidence and upheaval failure. Combined with a shield tunnel construction practice, the theoretical and measured values are compared. The results show that the theoretical equations are valid and can provide a theoretical approach for the parameters of shield synchronous grouting.
In order to calculate earth pressure in working chamber, three calculation modes which corresponding to status of elastic balanced, active limit equilibrium and passive limit equilibrium of the soil on the excavation face was built. The relationship of relative displacement between the soil in the chamber and the soil on the excavation face of shallow EPB shield tunnel was analyzed based on Rankines earth pressure theory. The threshold of chamber earth pressure values which correspond to the limit states of subsidence and upheaval were deduced and the reasonable range of the values were obtained. Combined with a shield tunnel construction practice, the theoretical and measured values are compared. The results show that the theoretical equations are valid and can provide a theoretical approach for the selection of chamber earth pressure.
Chamber earth pressure is one of the significant parameters during the Earth Pressure Balance (EPB) shield construction processing. The soil arching effect is existence when the tunnel depth is enough. It is significant to consider the influence of arching effect to analyze the pressure in soil chamber in shield tunneling. In this paper, the influence of arching effect is considered to calculate the chamber earth pressure. Firstly, the soil is supposed as loose media, and the necessary buried depth of producing arching affects is deduced according to the loose media theory. Then, based on the characteristic of proper arching axis, the equation and the height of proper arch are obtained. At last, the calculation formula of minimum chamber earth pressure of EPB shield tunnel is deduced which can consider the effect of arching effect.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.