1.State Key Laboratory of Water Resource Protection and Utilization in Coal Mining,Beijing ，China；2.School of CivilEngineering,North China University of Technology,Beijing ，China；3.Institute of Rock Instability and Seismicity Research，Dalian University ofTechnology，Dalian ，China；4.Northwest A&F University,Yangling ,China

Most of the rock masses have varying degrees of damage and there are a large number of cracks.When the stress waves propagate through the cracks, wave velocity, energy attenuation and time delay will occur.In order to clarify the time delay law of stress wave passing through the coal rock mass, and quantitatively analyze it, invert the internal damage degree of coal and rock mass, and use numerical calculation method to study the propagation law of stress wave in a single fractured coal rock.The waveform characteristics of the stress wave before, during and after the seam are analyzed, and the crack width, load parameters and delay parameters of the rock layer parameters are analyzed.The results showed that the stress wave time delay was positively related with the factors such as width, density and load cycle.The sensitivity order of the factors was:crack width>modulus of elasticity>rock density>load amplitude>load cycle.Among them, the delay time caused by crack width could be 0.23 times of the load cycle.The results reveal that the continuum-discontinuum element method program could well simulate the propagation of stress wave in the fractured rock.

煤炭开采水资源保护与利用国家重总实验室开放基金资助(SHJF17-42.15)；国家自然科学基金面上资助项目（51774184,51774064）