Research On Fault Technology On The Fully Mechanized Highmining Height Longwall Working Face In Steeply Dipping Seam

The phenomenon of hydraulic support falling and sliding in longwall fully mechanized mining face of high dip coal seam occurs frequently,and it is difficult to straighten.The production is low and the efficiency is poor,which seriously restricts the safe and efficient production of this kind of coal seam.Based on the geological and equipment mining conditions of 6152 working face in Huashan mine of Panzhihua coal group,this paper analyzes the factors affecting the adaptability of hydraulic support in large dip seam by means of theoretical analysis,field measurement and numerical simulation,and establishes the mathematical model of hydraulic support adaptability evaluation by using fuzzy mathematics and analytic hierarchy process.The main results are as follows:(1)Dip angle,mining height,hydrological conditions,surrounding rock conditions and geological structure are important geological factors affecting the adaptability of the support.Complex surrounding rock and hydrological conditions are easy to cause roof subsidence,coal wall caving,floor heave and roof fall,which are the main reasons for eccentric load and noload of the support;Special geological structure is the main reason for potential safety hazards in the working face.(2)Compared with the four pillar shield support,the two pillar shield support has the advantages of light weight and simplified structure.The two pillar shield support has faster moving speed and lower structural damage rate.Under the condition of the same working resistance,the support reliability is higher and the adaptability to the working face is better;The strength of main structural parts such as top beam,base and column is an important factor to improve the adaptability of hydraulic support.(3)The mining cost is high,the output is low,the treatment is not high,the education level of front-line workers is uneven,and the support falling and sliding are caused by improper manual operation.Therefore,the safety awareness and skill level of workers are indispensable factors affecting adaptability.(4)Through numerical simulation,it is found that in the process of advancing the working face of 6152 working face in Huashan mine,the uneven load on the column and the base is obvious:the load on the column shows that the load on the left and right columns of a single support is uneven and has no obvious regularity,the maximum stress difference between the two columns is 60.25mpa,and the load on a single column shows the characteristics of upper section>middle section>lower section,with the maximum difference reaching 170.3mpa,and the column has the risk of lateral damage;The stress concentration in the connection area between the base and the column is obvious and complex.The tensile stress and compressive stress act together.The maximum tensile stress in a single connection area is 35.76mpa and the maximum compressive stress is 176mpa,which has potential safety hazards of damage.(5)The maximum Mises stress of the upper section of the left column is 501.3mpa,the maximum stress of the middle section is 297.7mpa,the maximum stress of the lower section is 94.08mpa,the maximum stress of the upper section of the right column is 419.9mpa,the maximum stress of the middle section is 134.8mpa,and the maximum stress of the lower section is 53.36mpa.The stress value of the right column is small,and the stress concentration area is significantly smaller than that of the left column.The increasing trend of the two columns is upper section>middle section>lower section,which indicates that the upper section of the column has fatigue deformation,and the right column has hidden danger of fatigue deformation.(6)The adaptability evaluation model of hydraulic support in large dip coal seam is established by using fuzzy mathematics and analytic hierarchy process,the judgment matrix and evaluation model are obtained,and the consistency test is passed.The adaptability evaluation result of hydraulic support in 6152 working face of Huashan mine is "unsuitable",which is mainly caused by the overweight of support and the failure of anti falling and anti-skid device.