中煤新集能源股份有限公司

China’s coal-forming conditions are harsh, the coal-bearing environment is complex and changeable, and the resources are distributed in a global, multi-geological type and scattered distribution, resulting in frequent occurrence of mining-associated geological disasters. At the same time, with the optimization and regulation of coal resource development layout, the negative orientation of coal seam floor water damage is becoming more and more significant. The synergistic effect of high confined water hydraulic drive and strong sensitive defect structure activation leads to a significant increase in the threat of macroscopic dynamic representation of coal seam floor water damage, which has become an endogenous resistance to the high-quality transformation and development of coal resources in China. In order to grasp the development situation of coal seam floor water disaster in China in an all-round way and discuss the key research direction of prevention and control operation based on new technology in the future, the dynamic evolution trend of coal seam floor water disaster in China in recent years is comprehensively demonstrated from the multi-dimensional perspectives of time, space and water inrush quantity. The type is divided into “total-sub” type, and the mechanical mutual feedback response mechanism of coal seam floor water disaster in China is discussed by establishing geomechanical model. Based on the macroscopic representation of disaster, the endogenous disaster-causing mechanism is revealed, and the new development path and vision orientation of prevention and control technology concept are pointed out. The results show that: The evolution law and characteristics of coal seam floor water disasters in China from a multi-dimensional perspective are statistically analyzed, and the main framework of coal seam floor water disasters in China is discussed and established. According to the accident core cause system and macroscopic disaster-causing representation, the coal seam floor water disasters are divided into three categories: karst collapse column water inrush, fault activation water inrush and fracture-induced (composite) limestone water inrush, which are further refined into 12 subcategories, such as full-path through incremental water inrush (karst collapse column), through coal seam water inrush (fault), single-layer direct water inrush (fracture) with mining and unloading. The geographical spatial distribution of water disasters in three major types of coal seam floors was analyzed independently. The mechanism of ground stress and confined water pressure on the alienation development of confined water conduction path in the process of water inrush from karst collapse column is analyzed. The water inrush mode of floor karst collapse column induced by dynamic/static load disturbance of overburden roof is proposed, and its mechanical starting conditions and disaster-causing mechanism are clarified. The generalized model of macro-micro geomechanical structure of coal seam floor fault is established. Based on the identification of the core disaster-causing factors that induce fault activation water inrush, the mechanical criteria of fault activation water inrush in different types of coal seam floor are established. Based on the fracture as the basic unit, the critical discriminant conditions for the inrush of fissure-type ascending (composite) limestone water induced by single-layer and composite-layer confined aquifers are established by the formula of “one to n”, and the disaster-causing mechanism of the whole process of this type of floor water disaster is revealed. On the basis of summarizing the current concept of coal seam floor water disaster detection, prediction and control technology, combined with the frontier development direction, it is pointed out and suggested that the three-dimensional dynamic reconstruction of the whole life cycle mining-induced mutation characteristics of the background geological gene of the coal seam floor, the upgrading of the concept of coal seam floor water inrush prediction and prediction suitable for the dynamic geological environment of space-time differentiation, the application of low disturbance and strong intervention with mining\water control and mutual grouting treatment technology, and the establishment of long-term monitoring, diagnosis and treatment platform for geological ecosystem after restoration should be carried out to build a large system of full-time and space-time prevention and control of coal seam floor water disaster, and keep up with the development of new formats in the whole coal industry under the background of new productivity.

Mining subsidence represents the primary environmental geological challenge in coal mining,particularly at high water level mining areas in the eastern regions of China.The control of movement deformation and the assessment of ecological losses in the context of extremely thick loose layers have garnered significant attention.To investigate the in-ternal movement mechanisms of extremely thick loose layers and ascertain their impact on surface movement and deform-ation,this study focuses on the Xinji mining area in Huainan.A comprehensive 600 m depth full-section drilling monitor-ing system is established using the combined testing technology of distributed optical fiber and parallel electrical methods.This system aims to explore the deformation characteristics and internal movement patterns of the extremely thick loose layer.The full-section monitoring system captures internal strain and displacement information within the coal seam min-ing area,monitors changes in resistivity around the borehole,quantifies the spatio-temporal relationship between deforma-tion in the stratum monitoring section,and analyzes the deformation characteristics and development forms of the inner stratum of the loose layer.Results indicate that the application of multi-parameter joint testing technology significantly en-hances the monitoring efficiency and the accuracy of deformation location in the extremely thick loose layer.A relation-ship between the mining position of the working face and the internal deformation of the loose layer is established,divid-ing the mining influence process into four periods:the pre-influence period,weak mining influence period,strong mining influence period,and post-mining settlement period.The observed"reverse 3-shaped"shape movement model during ad-vance influence deformation is verified,and the constitutive conditions and influencing factors of this model are analyzed.This model reveals the law of the accumulation and release of stratified stress during the process of coal mining in the ex-tremely thick loose layer.The research outcome provides an essential technical support for the fine monitoring and analys-is of the internal movement and deformation of the extremely thick loose layer.The acquired technical data serves as a crucial reference for monitoring and evaluating the progression of mining-induced damage,mitigating losses,reducing subsidence in ecological mining areas,devising land planning strategies for subsidence regions,and assessing the effect-iveness of grouting transformations in loose geological layers.

[Objective]In coal mining engineering,damaged well walls pose a threat to the safety of production facilit-ies and mines.Comprehensively monitoring the impacts of shaft grouting on the deformations of mine surface plants and surface buildings is critical for ensuring the safe production of mines.[Methods]This study investigated a coal mine in the mining area within northern Anhui Province.Using the 15 scenes of Sentinel-1A image data covering the coal mine and the differential interferometric synthetic aperture radar(D-InSAR)technology,this study comprehensively mon-itored the subsidence of mine surface plants and surface buildings before and after shaft grouting,obtaining information on the dynamic deformations of surface and buildings.Accordingly,this study analyzed the impacts of grouting on the surface and buildings.[Results and Conclusions]The results indicate that compared to leveling measurements,the D-InSAR-based land subsidence monitoring yielded an average error of 1.70 mm and a maximum error of 2.70 mm.These results demonstrate the reliable accuracy of D-InSAR in monitoring minor land subsidence,thus meeting the require-ments for land subsidence monitoring in mine surface plants.Before shaft grouting,the surface and buildings were in a continuous subsidence state,with a maximum subsidence of 21.12 mm recorded during the monitoring period.After shaft grouting,their subsidence slowed down and then gradually stabilized.The analysis of shaft strain monitoring res-ults and changes in land subsidence reveals that the grouting engineering exhibited remarkable remediation effects by forming an impermeable curtain around the shaft.The monitoring results show that the surface underwent four deforma-tion stages,i.e.,continuous subsidence,slight uplift,minor subsidence,and stabilization,before and after grouting.Spe-cifically,initial grouting demonstrated a pronounced effect in curbing land subsidence.As the grouting progressed,the surface was slightly uplifted,followed by minor subsidence until stabilization after grouting completion.During the monitoring period,the deformations of major buildings remained within the safety threshold according to the Class Ⅰ damage criterion specified in the Regulations for Coal Pillar Retention and Coal Mining thereunder for Buildings,Wa-ter bodies,Railways,and Main Shafts(2017 Edition).Therefore,grouting engineering can ensure the safety of buildings by further mitigating their deformations.