Conglomerate is a kind of terrigenous sedimentary rock, which is the main component of gravel layer, its mechanical properties and failure mechanism are the basis of efficient rock breaking method developing while drilling in gravel layer, where lots of high-quality oil and natural gas resources had been discovered. The gravel content of the specimen was obtained by CT scanning and the mechanical properties of conglomerate were tested. A kind of simulating method for analyzing the mechanical properties of conglomerate and studying its influencing factor was proposed base on discrete element method, and the meso-mechanical parameters were calibrated by trial and error. According to the established DEM model, the mechanical properties of conglomerate under different meso parameters are studied, the results show that the crack propagation and stress-strain curves of numerical and physical test are in a good agreement. The number of meso particles and the loading rate of axial stress do a great to the computing time, but show a little influence on the elastic modulus of conglomerate. With the increase of meso particles, the UCS increase linearly first and then the growth rate decrease, while the UCS increase linearly continuously with loading rate of axial stress. There are different failure patterns such as cementation failure, matrix failure and gravel failure under a series of cementation strength ratio between the matrix and gravel particles. This research is of great significance to the exploration of the physical and mechanical properties of the bottom rock in gravel layer.

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