Experimental Study On Compressive Performance Of CA Mortar In The High-speed Railway

As the elastic cushion of slag-less slab track in the high-speed railway, the performance of cement asphalt mortar is crucial to the durability and safety of slab track. In this paper, experiments were conducted to study the influence of different loading rate and confining pressure on the compressive performance of CA mortar, meanwhile the right constitutive model was selected to describe the stress and strain state under different conditions of loading rate and confining pressure, and finally the influence of the track structure under different degradation of CA mortar layer was analyzed. Through the experimental study and theoretical analysis, the main research results can be concluded as follows:1) Through the compression tests of CA mortar under five different loading rates, it can be concluded that in a fixed proportion, settled test temperature and no confining pressure situation, the compressive strength and elastic modulus of CA mortar greatly increase with the increase of loading rate, and it shows a linear relationship between them. Moreover, the crack propagation rate increase with increase of the loading rate, and the cracks bifurcated easily in the propagation process, which caused fracturing of the CA mortar.2) Through the compression tests of CA mortar under five confining pressures, the results indicate that in a fixed proportion, test temperature and loading rate situation, the compressive strength and elastic modulus of CA mortar greatly increase with increase of confining pressure, and it shows a linear relationship between them. The increase of the confining pressure constrains the growth of the primary micro crack, and the failure pattern of CA mortar was gradually changed from splitting or local peeling off to waist drum deformation.3) Based on the test results of CA mortar, it can be concluded that since the stress hardening and softening and the shear dilatancy(shrinkage) were taken into consideration in Nanshui nonlinear model, it is suitable to simulate the stress-strain status of CA mortar under different confining pressures and its model parameters changed regularly with the variation of the confining pressure. Moreover, the correction model, which is based on the Nanshui nonlinear model, can be better used to simulate the stress and strain state under no confining pressure and different loading rate, and it also shows a certain relation between the model parameters and loading rate.4) By summarizing the common degradation phenomenon of CA mortar layer, the static methods were use to analyze the influence of the track structure under different degradation. Analysis result shows that, the stress and deformation of the track increase gradually with the deeper of edge deterioration and fracturing of CA mortar layer, and thus affect the smoothness and safety of the track. Besides, as the length of void between the slab track interface and CA mortar layer increases, the frequencies of structure decrease so that makes it more likely for the occurrence of the sympathetic vibration and thus affect the safety of the structure.