Study On The Stability Analysis And Supporting Effect Of Broken Surrounding Rock Roadway

Based on the background of broken surrounding rock roadway in a mining area of Sanmenxia,this paper analyzes the stability and supporting effect of roadway.Broken surrounding rock have been a common and difficult problem in underground engineering,with fissure development and low overall compressive strength.In the underground mine mining process,often encounter large deformation of the roadway,serious damage and other problems,resulting in support difficulties and unsatisfactory results,to the mine's safety production brings hidden problems.A combination of field investigation,indoor tests,theoretical calculations and numerical simulations was used to study the support problem of broken surrounding rock roadway in a mining area in Sanmenxia.Its purpose is to evaluate the stability level of broken surrounding rock roadway,solve the deficiencies of the original support design of the mine,ensure safe and efficient mining,meet the needs of mine production and improve economic efficiency.The main areas of work accomplished are:(1)Field survey and measurement analysis of the three middle roadways rocks of +260m,+295m and +330m in the mine area was carried out using the detailed lineage method,and the results show that the fractures of the mixed granite group in the mining area are developed,and the joint base distance is mainly concentrated at 0.2 to 0.6 m,this area belongs to broken and extremely broken rock mass,and its stability is poor.The dominant structural surfaces of the three central mixed granite groups are 341°?83°,17°?72° and 18°?72°,with roughness coefficients JRC concentrated at 6 to 10.(2)Field sampling and petrophysical-mechanical property testing of the mine site yielded physico-mechanical parameters for molybdenum ore,tuff and mixed granite.Among them,the three types of rocks under single-axis compression conditions mainly show brittle,single-slope shear damage form,with a small amount of tensile damage.The all-stress-strain curves of the three rocks exhibit significant plastic-elastic disruption,with a long plastic deformation time and an insignificant division of the disruption-deformation phase.Mass classification of the three rocks using the BQ classification method indicates that the chert mass is Class III and the molybdenum ore and mixed granite are Class V.The rock block strength is generally high,but the overall strength is low and support is difficult.(3)Based on the Uncertainty Measurement Theory(UMT),a single-indicator measurement model with nine influencing factors and five grading criteria was first established,and the combined primary and objective weights were optimized by the coefficient of variation method,and finally the surrounding rock grade was determined by the minimum Uncertainty Measurement Distance Determination(UMDD)method.Analysis indicates that the +260m middle section is a Class IV(generally unstable)perimeter rock,which is more in line with the actual mine.The UMT model developed provides an effective method for determining the stability of the surrounding rock.(4)Under the condition of no support,the main occurrence of the roadway is in the form of arched fall,cylinder fall,irregular fall and sheet gang.Under the supporting conditions,the main forms are the top beam bending and sinking,the two help shed foot force extrapolation and the collapse and fall of the top plate ore rock after the back plate fracture.The main external forces that are affected are overburden pressure,tectonic stress,expansion stress,loose and broken block pressure,the influence of supporting pressure and impact ground pressure.The form of damage in the mine area affected by static pressure in the alleyway is directly related to the depth at which the roadway is located.The roadway affected by the dynamic pressure has many forms of damage,the roadway damage area is large,the damage is serious,the damage area is different,the damage is intermittent and other characteristics.The deformation of the alleyway was significantly disturbed by faulting and blasting.Although the deformation of the mine channel is affected by many external forces,it is necessary to improve the support strength of the surrounding rock itself,improve the quality of construction and the form of support,and optimize the stressing and overburden conditions of the surrounding rock.(5)The top plate sunken,two groups of internal squeeze and bottom plate drums appeared after the fracturing of the perimeter rock roadway.The vertical stress and the minimum principal stress of the unsupported and different forms of support of the roadway are both located in the roadway at twice the width of the roadway on both sides of the roadway to form a "auricular type" compressive stress concentration,in which the size of the vertical stress is 16 ~ 20 MPa,the minimum principal stress size is 1.6 ~ 2.1MPa.The maximum main stress is distributed in a " bowknot" type after the roadway excavation,and at the same time,the horizontal direction of the roadway on both sides of the formation of a 4m distance from the roadway,the size of the 6MPa band-shaped stress area.The range of distribution of minimum primary stresses under different forms of support is less variable.The bolt-based support system is applied to broken surrounding rock support,which can well control the displacement around the roadway.The bolt,anchor spray,anchor spray + anchor cable support can control the maximum roof displacement to be reduced by about 50 %,60% and 80%.Bolt and shotcrete support has obvious improvement effect on the surrounding rock stress and plastic zone of the roadway,which is recommended for mines.At the same time,it is recommended to use hardened concrete floor to control the roadway bottom drum.