Abstract The exit of Maoyushan tunnel on Lanzhou-Chongqing railway is embedded in thin -layered carbonaceous slate stratum with high in-situ stresses of primary rock and horizontal tectonic stresses. During tunnel excavation, intensive large deformations and serious failures occurred due to high in-situ stresses and maximum horizontal principal stresses intersected with the tunnel axis with a large angle. Measures such as improving support system stiffness, lengthening systematic bolts, reasonable allowances for deformation and multi-support as well as super-short bench excavation were adopted to control the deformation of surrounding rocks. In addition, based on the understanding of the mechanism of dynamic evolution of rock masses, the technology of stress releasing by advance adit was adopted, and large-scale engineering tests were carried out. Test results showed that the advance adit efficiently reduced the deformation rate during the main tunnel construction, especially during the excavation of upper bench and middle benches. It is expected to find a safe and efficient construction method of tunnels in soft ground with high in-situ stresses by further study on stress releasing technology by adopting advance adit.
Abstract：
The exit of Maoyushan tunnel on Lanzhou-Chongqing railway is embedded in thin -layered carbonaceous slate stratum with high in-situ stresses of primary rock and horizontal tectonic stresses. During tunnel excavation, intensive large deformations and serious failures occurred due to high in-situ stresses and maximum horizontal principal stresses intersected with the tunnel axis with a large angle. Measures such as improving support system stiffness, lengthening systematic bolts, reasonable allowances for deformation and multi-support as well as super-short bench excavation were adopted to control the deformation of surrounding rocks. In addition, based on the understanding of the mechanism of dynamic evolution of rock masses, the technology of stress releasing by advance adit was adopted, and large-scale engineering tests were carried out. Test results showed that the advance adit efficiently reduced the deformation rate during the main tunnel construction, especially during the excavation of upper bench and middle benches. It is expected to find a safe and efficient construction method of tunnels in soft ground with high in-situ stresses by further study on stress releasing technology by adopting advance adit.
LI Ting-Chun
.Large Deformation Control Technology for Maoyushan Tunnel in Soft Rock under High in-situ Stresses[J] MODERN TUNNELLING TECHNOLOGY, 2011,V48(2): 59-67
2011, Vol. 48 