Roadway Backfill Mining with Super-High-Water Material to Protect Surface Buildings: A Case Study

Abstract

As coal resources trapped under surface buildings in the Wangtaipu coal mine area impede the efficient mining of coal seams and constrain the sustainable development of coal mines, a super-high-water roadway backfill mining technique for preventing building damage was adopted. According to the control principle and theoretical calculations, an engineering design was established including the reasonable width of segment coal pillars in the working face and technical parameter design. The monitoring results after the implementation of the scheme showed that building deformation was controlled within grade I, protecting the surface buildings. A reasonable roadway design parameter was achieved, with a surface subsidence of 27 mm and horizontal deformation of 0.3 mm/m, indicating that it can ensure the safety of surface buildings from the State Bureau of Coal Industry. The practical trial can provide a reference for the extraction of coal resources under similar conditions and is vital for the sustainable development of the mining industry and economic growth. This is because the remaining coal pillar can usually support the overburden load, allowing slight surface movement and deformation. Although the strip mining or room mining method has reduced surface subsidence or damage to a certain extent, the mining rate is low due to the coal pillars. Because the harmonic mining is limited by many factors, such as construction organization, geological conditions, and subsidence factor, it is difficult to realize. Meanwhile, grouting injection technology has been successfully applied to reduce surface subsidence and building damage in populated areas. Alehossein [16] studied shear behaviour of the slurry through field and laboratory testing, and derived formulas for minimum pump pressure and local pressure, and the results are consistent with each other. Shen and Poulsen [17] used numerical modeling to study the evolution of horizontal fractures at bed separations during longwall mining. By analyzing the influence of filling ratio and maximum subsidence on the grouting effect, Xuan and Xu [18] obtained the supporting width that was formed at the center of the gob. Subsequently, the stiffness and distribution of the grouting mass were investigated through field borehole, and the mechanism of grouting to restrain the overburden deformation was revealed [19]. Considering the long-term stability of overburden, the effect of harmonic mining and grouting injection on overburden damage reduction is poor. In fact, the essential problem of "under-three" mining is controlling the movement and deformation of the overlying strata. By contrast, backfill mining has been widely used and is becoming an effective technique for reducing the degree of overburden failure in the green mining technical system, and has been developed to solve the global problems described above, especially for "under-three" mining [20][21][22][23]. In essence, backfill mining reduces the overburden movement by replacing the coal with backfill material. Meanwhile, ...

Study on Physical and Mechanical Properties of High-Water Material Made by Seawater

“…Initially, HWM was utilized mostly for back-filling, roadway support, etc., in underground coal mining [27][28][29][30]. Recent studies indicate that HWM has a promising application in maritime environments.…”

Numerical Investigation on the Compressive Behavior of Desert Sand-Based Backfill Material: Parametric Study

“…High-water backfill materials (HWBMs) have high early strength, a short gelling time, a simple construction technology, and other advantages [ 1 , 2 , 3 ]. Many mines have used HWBMs for goaf filling and roadway side support [ 4 , 5 , 6 ].…”

Effects of Aeolian Sand and Water−Cement Ratio on Performance of a Novel Mine Backfill Material

“…Concern about many serious eco-environmental problems caused by coal exploitation is a global problem [1,2]. As a result, much research in recent years has focused on the development of mining techniques that are environmentally friendly [3]. Under the rapid development of the mining industry in recent decades, the continuous and irreparable impacts of contaminated air, degraded soil, polluted water, damaged biodiversity, and geological disaster of mining operations may increase the risks of mine development [4].…”

“…Recently, some new backfill materials have been developed, such as flexible formwork concrete, high-water backfill material, and cement mortar. Such novel backfill materials somehow reduce the backfilling cost and expand the application scope of the backfilling technology [24][25][26][27][28], such as roadway backfill mining [3] and pillarless coal mining [20].…”