## 1 Introduction  
The recoverable reserves of coal are decreasing increasingly, especially in developed eastern regions, because it is non-renewable energy. Coal mining encounters more serious pressure with the development of the economy [1; 2]. The traditional mining mode under buildings has a low recovery rate, which results in the waste of coal resources. It also pollutes the ecological environment, etc. [3; 4], and seriously affects the sustainable development of mines. Therefore, environmentally friendly mining technology is needed to solve the above problems. The concept of green mining has been focused on by the mining industry. Many scientific and technological workers have studied the system and proposed some technologies like paste-filling mining, gangue-filling mining, high-water-filling mining, water retention mining, and separation zone-filling mining [5; 6; 7; 8]. Paste-filling mining technology, as an important mining method in the green mining system [9; 10], is being practiced in vast coal mining areas. Paste-filling technology was first applied in metal mines. It mainly experienced four development stages: dry filling, water-sand filling, low-concentration cemented filling, and paste filling, according to the development of filling technology [11; 12]. The primary purpose of the earliest filling was to dispose of solid wastes such as tailings and coal gangue. Poland, Germany, and other countries adopted water-sand filling technology to re-mine coal under buildings and protect the land surface buildings by the 1940s and 1950s. The problem of coal mining and coal gangue treatment under buildings is prominent in eastern China in the 21 st century, so the filling mining technology enters its trial in eastern China and is gradually applied in coal mines. China's paste-filling mining technology was first successfully tested in Taiping Coal Mine in May 2006. Later, it was gradually applied in the Daizhuang Coal Mine and Xuchang Coal Mine of Zibo Group in Shandong Province in 2009 after summarizing technical experience and exploring filling methods under various geological conditions. Experiments have been conducted on coal mining with water and secondary filling mining technology of strip coal pillars under buildings. The research direction of paste-filling coal mining technology has been explored through years of research [13; 14; 15]. Researchers have studied paste-filling mining-related technologies. [PERSON] studied the overlying strata movement law of paste-filling mining [16]. [PERSON] used void conservation theory to study the rock layer control and filling technology of paste-filling mining [17]. [PERSON] studied the overlying strata deformation and earth surface subsidence theory of filling mining based on the elastic foundation beam theory [18]. [PERSON] studied the overlying strata movement law of filling mining by numerical simulation [19; 20; 21; 22]. However, the above studies are conducted on the overlying strata movement of filling the working surface. Research is at the early stage of the paste-filling technology of the industrial demonstration site. The filling working face has a low efficiency of recycling strip coal pillars or filling in the period. Therefore, the law of overlying strata movement in filling mining cannot be demonstrated systematically. The paste-filling mining technology has been further improved to a higher level of large mining amount, efficient filling, and intelligent control after decades of technical development. Gaohe Energy's longwall paste-filling working face adopts the latest research of isolation filling support with the present high efficiency. It comes with a large displacement filling system and a reasonable proportion of filling materials. The overall filling mining efficiency has been increased by more than two times, and the annual filling mining capacity has reached 1 million tons.