A series of static and dynamic mechanical tests were carried out to investigate the mechanical properties of C-Type Group Material(CGM)cementitious grout and the failure law of damage under dynamic loading conditions.On the basis of the tests,the parameters of the Holmquist-Johnson-Cook(HJC)dynamic principal structure model of the material were calibrated and finite element dynamic simulations of the Split Hopkinson Pressure Bar(SHPB)test were carried out based on LS-DYNA software.The test results show that the CGM cementitious grout is mechanically stable and exhibits significant brittleness under uniaxial stress conditions,significant elastoplasticity under loading with surrounding pressure and significant rate effect under dynamic loading conditions,When the strain rate reaches 119 s-1,the dynamic peak strength can be increased by 1.62 times.The numerical simulation results show that the peak stress and peak strain of the CGM cementitious grout before damage at different strain rates can be accurately predicted using the HJC constitutive model parameters calibrated from the test data,which provides a reference for the application of this material under dynamic impact.