限阻耗能型支护结构在单线铁路隧道大变形中的应用研究

Application of Support-Resistant Limiting Damper in Single-Track Railway Tunnel

为解决单线铁路隧道施工过程中遭遇的高地应力软岩大变形进而导致的初期支护破坏问题,对原直板形限阻器进行优化,研究其在不同优化参数下的力学性能,并将其应用于中老铁路沙嫩山二号隧道单线段,开展限阻耗能型初期支护现场试验。通过限阻器性能参数试验研究和施工应用效果研究,得出以下结论:1)弧板限阻器受压变形时方向可控,有效行程得以提高,经历弹性变形、屈服下降变形、恒阻塑性变形和压实上升4个阶段。2)改变限阻器竖向钢板径高比可以改变限阻器的初始应力峰值,但对恒阻应力值的影响很小,实际应用限阻器时应选取对应初始应力峰值为8 MPa时的径高比较为合适。3)试验段采用限阻器后,围岩压力得到释放,避免了初期支护过载破坏,在未加强初期支护参数的前提下,既保证了支护结构的安全性,又提高了经济性。

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.