Research on the Stress Characteristics of Initial Tunnel Supports Based on Active Load Adjustment

Abstract

Initial tunnel support takes on a critical significance in the stability control of surrounding rocks and the core content of tunnel support design. Its stability and safety are essential to the tunnel. The support load was optimized using the active surrounding rock load intervention scheme in accordance with the section form and bearing characteristics of the support structure. The optimization scheme of active surrounding rock load was obtained by applying active intervention load to the initial support of the tunnel to minimize the peak moment of the support structure. An active adjustment system for tunnel-surrounding rock loads was developed using the function of hydraulic load transfer and transmission combined with load proportion control. Based on the actual project, the implementation effect of the surrounding rock load active intervention scheme was verified by analyzing the measurement results of the supporting structure in the test section and the comparison section. The results suggest that the application of active intervention load can effectively improve the stress state of the tunnel initial support structure, significantly reduce the tunnel surrounding rock bias pressure and the structural peak bending moment, and increase the stability of the support structure. To control the peak moment of the supporting structure, an active intervention method and its implementation scheme for the stress of the tunnel supporting structure were proposed, which reduces the deficiency in which the conventional supporting structure can only passively bear the deformation pressure of the surrounding rock, effectively improves the stress state of the supporting structure, and can provide a reference for the development of novel tunnel supporting forms.

Deep Rock Mass Engineering: Excavation, Monitoring, and Control

“…Moreover, timely grouting can reduce the damage to shield tunnels. K. Ma, L.-P. Chen, and Q. Fang [22] proposed a transfer method using tunnel surrounding rock loads to optimize the bearing capacity of the initial support, which was verified by Miaoshan tunnel engineering. Their research findings provided guidelines for the design of tunnel support.…”

Research on Double-Layer Support Control for Large Deformation of Weak Surrounding Rock in Xiejiapo Tunnel

“…Ref. [26] constructed a ring structure composed of 15 adjustment units. By controlling and adjusting the position and diameter of the units, they optimized the main power system of the tunnel lining, demonstrating that the deformation of surrounding rock around primary supports could be controlled.…”