Study On Mechanical Response Of Surrounding Rock And Support Technology When Encountering Near Parallel Old Roadway During Working Face Excavation

In order to ease the tension between mining and excavation,Hanjiawa coal mine excavated the 22403-working face.During the excavation and transportation along the channel,a nearly parallel old lane of the original Maoguantun 1# old lane with an included angle of 1 ° 10 ’was exposed.According to the geometric relationship between the 22403 transportation along the channel and the old lane,the width of small coal pillars between them is in the process of change,and the surrounding rock of the roadway has different bearing properties,Therefore,this paper takes the near parallel old roadway in the 22403 heading face of Hanjiawa coal mine as the engineering background,and studies the coordination relationship between the support technology of the near parallel old roadway in the heading face and the dynamic bearing performance of the surrounding rock.The high intensity of coal mining has resulted in the tight connection between mining and excavation in Hanjiawa coal mine.The main measures to alleviate the tight connection between mining and excavation are as follows:(1)develop the integrated and efficient operation platform of roadway excavation,anchor and support;(2)The coal mining technology was innovated,and the high-efficiency coal mining methods such as small coal pillar heading and driving roadway,roof cutting and pressure relief and gob side entry retention were studied.Firstly,aiming at the problem of efficient roadway excavation,the advance support load and structural optimization of the excavation anchor support integrated platform are summarized and analyzed.A monorail anchor support cooperative machine in the fully mechanized face is designed.The structural strength of the anchor drill system is checked by numerical calculation,the dynamic model of the fully supported state of the whole machine walking system is established,the vibration differential equation of the whole machine walking system is derived,and the vibration response characteristics of the walking system are studied,the supporting effects of composite support net and rigid support net are compared and analyzed.Secondly,the physical and mechanical properties of the rock stratum were measured through on-site sampling,which provided basic data for the support design,and the development characteristics of the primary fractures of the roof were mastered through on-site drilling.The physical tests showed that after the mudstone and sandy mudstone of the roof and floor experienced the water absorption air drying cycle,the rock samples broke and disintegrated,and the disintegrated materials accumulated in pieces;Although the sandstone does not disintegrate,it is easy to be disconnected from the mudstone interlayer after water absorption air drying cycle,which is also unfavorable to the support and should be paid attention to in production.Finally,considering that the coal pillar width between the 22403 transport chute and the two old roadways is constantly changing during roadway excavation,and the coal pillars in different areas have different bearing properties,therefore,the 22403 transport chute can be divided into the following three areas with different surrounding rock bearing properties: area(1)the distance between the 22403 transport chute and the 1# old roadway is less than 2m,and there is no coal pillar in the through expansion section;Area(2)the distance between 22403 transport chute and 135;old roadway is greater than 2m and less than5 m coal pillar section;Area(3)the distance between 22403 transport chute and 1# old roadway is greater than 5m coal pillar section.The roadway section in area(1)becomes larger,and the original design top bolt support in the old roadway is changed to 4.3 m short anchor cable to strengthen the support.The stability of area(2)and area(3)mainly depends on the stability of small coal pillars between the 22403 transport trough and the old roadway.The support of the side wall of the old roadway is mainly strengthened by the two split anchor cables arranged in "two · two" and cooperated with the W steel belt to connect the split anchor cables horizontally.The support schemes of the above three areas are completed by theoretical analysis and engineering analogy,and the rationality of the support scheme is verified by numerical simulation.During the mining period,22403 is easy to cause the plastic failure zone to be connected under the influence of mining.Although the measures of pulling anchor cable and transverse w-steel belt to strengthen the support of small coal pillars are adopted,there is still a risk of roadway instability.During the mining period,monomer columns and steel shed beams should be used in the old roadway roof to further strengthen the support to prevent roof falling accidents.The research results have important practical significance for the safety,efficiency and economic production of Hanjiawa coal mine.At the same time,the research results of this paper will enrich the surrounding rock control technology and theory of the old roadway in the working face,and provide reference guidance for similar projects.Figure [68] Table [13] Reference [86]...