## 2 Test Scheme Design  
### Monitoring Scheme of blasting Vibrations  
Within the effective range of blasting propagation, it is necessary to monitor and analyze the influence of blasting vibrations on buildings and take relevant measures to minimize the hazards the blasting. Figure 1 presents a schematic figure of ground buildings and advancing blast. The coal seam is classified as an extra-thick coal seam, with a thickness of 10.85-22.67 m and an average thickness of 16.4 m. The average burial depth is 250 m. The working face direction length is 1325 m, and the distance within 200 m of the buildings is defined as the final mining stage.  
The main monitoring components of blast weakening vibrations are the vibration velocity of the ground monitoring points and the main vibration frequency under the blasting seismic wave, etc. The NUBOX-8016 intelligent monitoring instrument (Tuopu Measurement & Control Technology Co., Ltd., Chengdu, China) of blasting vibrations was used for measurement. This system includes a meter host for blasting vibrations, a three-dimensional velocity sensor, and a signal connector. The meter host can collect the vibration velocity, duration, and main frequency of the blasting seismic wave at various monitoring points. Three directions, including x, y, and z, are measured using the sensor with three respective channels. The sensor and the meter host are connected through special signal lines. The parameters are adjusted. Then, the blasting vibrations can be monitored and recorded. Finally, the software is used to process, analyze and output the monitoring results.  
The 2303 working face has advanced about 930 m and remained at about 400 m in the stage of vibration monitoring. Because the ground seismic is already strong, it will cause damage to ground buildings or equipment due to the blasting vibrations. Therefore, the ground vibrations caused by the blast weakening in the 2303 working face of the remaining 400 m are monitored. The layout of monitoring points needs to consider the situation of the ground buildings. In this paper, the monitoring points are arranged on a representative industrial chimney (masonry structure), a six-story district office (frame structure), and a four-story science and technology building (frame structure). Figure 2 presents a schematic figure of ground vibration monitoring for blast weakening at the remaining 400 m of the 2303 working face. Monitoring point 1 monitors the science and technology building. Points 1-1 and 1-2 are located in the two diagonal vertices of the science and technology  
Figure 1: Propulsion schematic figure of the fully mechanized caving face and blast weakening.  
building and are facing the blast. Point 1-3 is located in the front middle of the building with its back to the blast. Monitoring point 2 monitors the district office and all points facing the blast. Points 2-1 and 2-3 are located in the two diagonal vertices of the district office. Point 2-2 is located in the front middle of the district office. Monitoring point 3 monitors the industrial chimney, and all of the points face the blast. Points 3-1 and 3-2 are located in the front and at the sides of the chimney. Point 3-1 is located in the front middle of the chimney.