Abstract: The previous analysis of the rock pressure of shallow bias tunnel is based on the particular friction angle to reflect the material characteristics of rock mass. However, the rock internal friction angle and cohesion are not as the independent parameters in their studies. Based on the standard method, a simplified theoretical analysis method for the rock pressure of shallow bias tunnel is proposed to consider the horizontal earthquake action and rock cohesion. The theoretical expressions of the vertical rock pressure at the location of tunnel top, the lateral pressure at the location of both sides of tunnel and the rupture angle of sliding surface are obtained. The factors affecting the top vertical and horizontal lateral pressure of surrounding rocks, and fracture angle are studied. The results show that the top vertical pressure of surrounding rocks is positively correlated with the friction angle of sliding surface and the slope angle, and negatively correlated with the level of seismic effect coefficient and slip surface. The greater the internal friction angle, the cohesion of sliding surface and the slope angle become, the greater the rupture angle becomes, while the greater the horizontal seismic acceleration coefficient becomes, the smaller the rupture angle becomes. The horizontal lateral pressure decreases with the increasing of the internal friction angle and cohesion, increases with the increasing of seismic effect coefficient and slope angle. The results can provide a theoretical basis for the calculation of surrounding rock stress of the shallow bias tunnel.

Key words: shallow bias tunnel, surrounding rock pressure, cohesion, horizontal lateral pressure, horizontal earthquake action