Abstract: The primary support of singletrack railway tunnels can be damaged owing to large deformations in soft rocks caused by high geostress. An optimization strategy for the original straightplatetype supportresistant limiting damper(SRLD) is presented and the mechanical properties of the optimized SRLD under different optimization parameters are examined. To conduct field tests on a restricted energydissipationtype primary support, the SRLD is applied to the singletrack section of the Shanenshan No. 2 tunnel of ChinaLaos railway. The results of the parameter test and the application of the SRLD are analyzed as follows. (1) The direction of the curvedplate SRLD is controllable when the plate is compressed and deformed, and the SRLD undergoes four stages: elastic deformation, yielddecline deformation, constantresistance deformation, and compaction rise. (2) Changing the diametertoheight ratio of the vertical connecting steel plate of the SRLD can change the initial peakpressure value of the SRLD, affecting the constantresistance value marginally. Therefore, in practice, the diametertoheight ratio of the vertical connecting steel plate of the SRLD must be selected according to the initial peak value of 8 MPa. (3) After the SRLD is used in the test section, the surrounding rock pressure is released to protect the primary support structure from invasion and limit damage. Moreover, the construction safety and economy can be guaranteed under the condition that support parameters are not strengthened.

Key words:

singletrack railway tunnel, large deformation, supportresistant limiting damper; compressiondisplacement curve, support structure