列车动载作用下锚索锚固力响应规律的研究

京石客专石家庄明挖隧道工程与既有京广铁路线近距离并行长达5km，既有铁路运营的长期振动必然对隧道支护结构稳定性造成影响。研究锚索锚固力动载响应规律、确定合理的锁定力值，是保证隧道支护稳定及铁路运营安全的关键环节。基于此，在石家庄隧道选取代表性区段，进行锚索锚固力长期监测现场试验。同时，利用FLAC-3D软件建立数值模型，分析总结锚索锚固力的动载响应规律。研究表明，在特定工况下，锚索支护结构存在-锚固力收敛阈值，仅当锁定力高于该值时，结构才是稳定的。锁定力在该范围内的变化对结构稳定影响不大。而当锁定力小于该值时，结构表现为对动载敏感。锚头位移随锁定力减小，呈抛物线函数关系增长，锚索应力变幅百分比随振源距离减小、振源强度提高而呈幂函数关系增长。以上规律部分地得到现场量测数据的证实。

RESEARCH ON RESPONSE LAW OF CABLE ANCHOR FORCE UNDER TRAIN DYNAMIC LOAD

In the project of passenger dedicated Line from Beijing to Shijiazhuang,a 5 km long tunnel parallel to the existing Beijing to Guangzhou Railway Line with a distance ranging from 5 m to 20 m was built with open excavation method.The longtime and continuous dynamic load caused by running trains would necessarily influence stability of tunnel supporting structure.So it was vital to establish the reasonable locking force value of anchor based on study on response law of anchor force.Thereby a site test was designed on a standard tunnel section and performed to measure anchor force for half a year.Meanwhile a digital model was made with FLAC-3D according to site condition and construction steps to analyse the law.The research showed there existed a critical value of locking force.Bigger than that,the supporting structure would be stable and the fluctuation of anchor force would not cause obvious stable problem.Smaller than that,the supporting structure was sensitive to dynamic load.Under the condition,the displacement of anchor head satisfied parabola function with locking force.The relative variation range of dynamic stress rised in line with power function with increase of vibration strength and decrease of distance of train.The test data partly proved the foregoing conclusions.