Research On The Mechanism Of High Confined Water Uplift And Water Inrush From Coal Floor Containing Concealed Faults

With the depletion of shallow coal resources,the increase in mining depth will face increasingly complex engineering and hydrogeological conditions,and mine water prevention and control will also face a more severe situation of water inrush from buried faults in the floor.The floor space concealed faults not only weaken the integrity and water resistance of the floor rock,but also have a significant disturbing effect on the dynamic distribution of the mining stress in the floor space.It is very easy to cause the hidden faults to activate the surrounding rock and send water,which seriously threatens the safety and efficiency of coal resources.Production work.Therefore,this paper aims at the scientific problem of the mechanism of confined water conduction caused by the concealed fault floor.Through field measurement,theoretical analysis,numerical simulation,etc.,the law of high confined water movement under the coupling action of high confined water and high mining stress is carried out.Experimental research on the formation law of water inrush channels,and the specific results are as follows:(1)Through literature statistical analysis method,the existing research results of floor water inrush mechanism,the classification method of floor water inrush type,and water inrush phenomenon have been systematically combed,and it is found that with the increase of mining depth,the occurrence of floor concealed fault outburst is gradually increasing.In order to reveal the water inrush mechanism of floor concealed faults,according to the different scale and spatial location of floor concealed faults,three types of water inrush modes of floor concealed faults are proposed:upper concealed fault water inrush,lower concealed fault water inrush,and communication with concealed fault water inrush,This article has conducted an in-depth study on the water inrush pattern of the underlying concealed fault.(2)Based on the slip line field theory,the floor mining failure mechanics model is established,and the theoretical calculation formula of floor mining failure depth is derived.This formula shows that floor mining failure depth and coal seam depth,coal wall supporting pressure range,floor rock Factors such as physical strength are closely related.Water injection test method,borehole peeping method,distributed optical fiber detection method and transient electromagnetic method are used to monitor the full space,dynamic and static state,and multi-parameters of the mining influence range of the working face floor.The monitoring results show the depth of the water-transmitting cracks in the floor mining.It is about 22 m,the depth of plastic failure due to mining is about 24 m,and the depth of physical property difference is about 30 m.Based on this,a grading model of coal floor mining response is established,and it is proposed to divide the impact of coal floor mining into water-conducting failure zones in the longitudinal direction,Small fissure zone and physical property difference zone,enrich the distribution law of floor rock mass mining influence.(3)Based on the semi-infinite body theoretical model,a mechanical model of mining stress transfer in the bottom plate is established,so as to obtain the calculation formula of the mining stress distribution in any space of the bottom plate.In addition,a dynamic model of water-conducting concealed fault mining was established,and fracture mechanics was used to analyze the fault activation stress intensity factor.Finally,the calculation formula of floor water-conducting concealed fault mining induced lift height was obtained,and MATLAB numerical analysis software was used to perform single factor analysis.The relationship between the influencing factors of the lead and the lead height are discussed.(4)Using FLAC^3D numerical software,the orthogonal test method was used to design a combined test plan for different fault inclination angles and different floor space positions.According to the characteristics of different concealed faults,the migration law of the floor high confined water was developed.Research and simulation results comprehensively show that under the influence of mining,stress concentration will occur in the surrounding rock of a hidden fault,and high confined water is more likely to move towards a hidden fault with good water conductivity.The larger the thickness of the hidden fault,the greater the dip,and the closer it is to water.The layer has more significant influence on the law of confined water mining movement.(5)In order to study the water inrush mechanism of floor concealed faults under the synergistic effect of mining and water pressure,FLAC^3D was used to simulate the evolution law of floor concealed normal and reverse fault water inrush channels,and the study found that hidden normal faults have a stronger effect on floor stress field disturbance than Concealed reverse faults,the former water inrush channel development scale is significantly larger than the latter,hidden normal faults are more likely to induce water inrush disasters.Based on this,the water inrush mechanism of the combined action of the mining stress and water pressure on the concealed fault floor is proposed,and a water inrush prevention and control technology of"precisely check the structure drainage and pressure reduction,and systematically manage the segmented and strong injection"is proposed for this situation.(6)Through the practice of grouting reinforcement for the inner and outer floor aquifers of the 182602 working face of Wutongzhuang Mine,the karst fissures and concealed water channels in the area were effectively sealed,the thickness of the relative water barrier was increased,and the water barrier performance of the treatment layer was improved.Increased the safety factor of No.2 coal mining,and met the design requirements.