Abstract: As a critical part of a tunnel, the tunnel entrance often encounters issues of shallow burial under bias pressure and poor stability of the surrounding rock. Completely weathered granite is characterized by a loose structure, poor intrinsic stability, and a tendency to soften and disintegrate when exposed to water. However, the knowledge on the stability of shallow-buried, biased tunnels in weathered granite is not completely understood . There is a pressing need to develop an appropriate tunneling technique to address the instability commonly encountered at tunnel portals in such conditions. Based on the Xiangsi Mountain Tunnel, this study analyzed the stability of tunnel entrances in shallow-buried and biased-pressure environments with completely weathered granite. Numerical simulations with tunneling method of three-step, seven-sequence circular excavation with core soil reservation were conducted to analyze the displacement of surrounding rock and the variation characteristics of internal support force. The results show that using anchor rod lattice beams and square frame slope protection on the deeply buried side can increase the safety factor of the side slope by 64.6%. Compared to traditional methods, installing anchor piles at the tunnel entrance and the slope toe can enhance resistance on the shallowly buried side by 13.7% and 10.1%, respectively. Due to compression from the deeply buried side, the tunnel tends to displace horizontally towards the shallowly buried side. The monitored displacement of the initial support closely matches the numerical simulation results, with a maximum difference of only 6.5 mm at the vault and a minimum difference of 2.6 mm at the right wall foot. The three-bench, seven-step circular excavation method with reserved core soil, combined with different support measures for the deep and shallow sides, can effectively improve the stability of shallow-buried biased tunnels in completely weathered granite. This study provides data support and engineering references for the design and construction of similar tunnel projects.