Currently, in many countries with the coal mining industry, the technology of using artificial pillars has been successfully applied to replace coal pillars to protect the entry gate road, thereby reducing the rate of resource loss, as well as the cost of entry gate road, and mining costs. However, in order to optimize the required width and compressive strength of artificial pillars with thickness, slope angle and mining depth, more detailed studies are required for each specific geological condition. This research uses Phase 2 numerical simulation software to analyze the stability of artificial protective pillar of the roadway prepared in the mining of medium-thick coal seams in the Quang Ninh coal region (Vietnam). The research results show that the relationship between the width of the artificial pillar and the slope angle follows the rule of a linear function. The size of the artificial protection pillar increases according to the mining depth. When the mining depth is 350m, the size of the pillar changes from 1.0 divided by 2.4m, and to 1.4 divided by 2, 8m at a depth of 500m. When the slope angle increases, the required pillar width also increases. That is due to the fact that at a large slope angle, the pressure acting on the pillar is not at the center, but deflects to the side adjacent to the entry gate road that needs to be protected, the compression force is not distributed evenly. The required compressive strength of the artificial pillar varies according to the condition of the slope angle, when the seam slopes 10 degrees, the required compressive strength is from 8 to 12 MPa, when the slope angle increases to 20 degrees, the required compressive strength of the pier increases to 18 divided by 28 Mpa, but when the slope angle increases to 35 degrees, the required compressive strength of the pillar tends to decrease to 16 divided by 17 MPa. Thus, when operating in the corresponding conditions, it is necessary to choose the size and required compressive strength of the artificial pillar to ensure the working capacity of the pillar.
