Abstract:  To address the large deformation issues of the Qiyun tunnel on the YuxiChuxiong highway, a design concept known as the supportresistant limiting damper(SRLD) is introduced and examined. Using static pressure testing, the schemes of the energyconsuming types of support elements and the pressuredeformation of the straight plate, arc plate, and inclined plate types of support elements are compared and analyzed. The results reveal that the arc plate SRLD has a constant resistance of approximately 3 MPa. Its initial peak value is less than the compressive strength of C25 concrete and compression deformation is controlled and oriented. Therefore, the arc plate type SRLD is selected and the optimized structure is applied into the Qiyun tunnel design. Based on SRLD performance in the large deformation tunnel, the following conclusions are drawn: (1) The support structure is controlled by deformation pressure. Except for the plastic deformation caused by SRLD during the design stroke, the remaining primary support structures operate within the elastic range, enhancing structural safety. The maximum pressure of the surrounding rock is only 0.13 MPa, indicating that SRLD can release this pressure effectively. (2) Concrete spalling and steel frame collapse are common in the primary support structures reinforced using conventional support methods, while the section supported by SRLD exhibits a good overall state because SRLD experiences only large deformations, indicating a good deformation control effect. (3) The processing method of the SRLD is simple and the construction technology is suitable for the bench method, which provides good operability and economic benefits.

Key words: highway tunnel, large deformation, energy release; supportresistant limiting damper, primary support optimization