Shallow Bias Small Spacing Tunnel Surrounding Rock Pressure And Construction Mechanics

Unsymmetrical loading neighborhood tunnel with shallow depth is a tunnel structure which interposes between the separable tunnels and multi-arch tunnels. Such tunnel structures are less complicated than multi-arch tunnel technology, easier to be dealt with water-proof technology and limit the construction expenses as well. Taking the practical engineering as example, this thesis is devoted to theoretical and numerical calculation methods on surrounding rock pressure in the unsymmetrical loading neighborhood tunnels, the numerical simulation in different construction methods are analyzed as well. By completing the theoretical calculation and numerical simulation, following research contribution are achieved:1. The interaction mechanics theory of surrounding rock and supporting tunnel in New Austria Tunneling Method is discussed by combining the intensity characteristics and constitutive relation of geotechnical materials;2. Based on forerunners' relevant theories and methods on surrounding rock pressure, the calculation methods of surrounding rock pressure of unsymmetrical loading neighborhood tunnel are promoted; with the relevant calculation formulas of surrounding rock pressure deduced as well;3. In accordance with the practical engineering, by adopting the theoretical calculation method and numerical simulation of surrounding rock pressure in unsymmetrical loading neighborhood tunnels, the distribution law of vertical stress and horizontal lateral compression of tunnel surrounding pressure are analyzed, the distribution characteristics and changing law of surrounding rock pressure due to different slope gradient, tunnel depth and tunnel net distance are discussed;4. The results of numerical simulation and theoretical calculation formulas are analyzed and compared, the reliability of theoretical calculation formulas of surrounding rock pressure under the aforementioned conditions are demonstrated, and the conclusion are achieved; 5. The numerical simulation of different construction methods (up and down steps, single sidewall guide pit, dual sidewall guide pit) are applied in the unsymmetrical loading neighborhood tunnel.