Study On Deformation Characteristics Of Surrounding Rock And Support Technology Of Concrete Filled Steel Tubular Supports In Lannigou Gold Mine Roadway

With the deep development of mining,the stability control of the surrounding rock of the roadway has become the primary problem that restricts the safe and efficient production of the mine.Under complex construction conditions such as "three highs and one disturbance",weak and broken roadway surrounding rocks,and fault fracture zones,traditional bolting and shotcreting,steel supports,due to limited strength and structural defects,make it difficult to effectively control the surrounding rock of the roadway.Tough problems such as roadway deformation and failure,supporting structure failure.This paper takes the support of deeply broken roadway in Lannigou Gold Mine as the research background,takes concrete-filled steel tube support as the research object,and uses a combination of site investigation,theoretical analysis,physical experiment,and numerical experiment to comprehensively analyze the surrounding rock of the roadway-support The coupling effect characteristics of the structure,and the research results are applied to engineering practice.Through the observation of roadway deformation and microseismic monitoring,the support effect of the concrete-filled steel tube support is quantitatively analyzed.The main research conclusions are as follows:(1)The rock quality of the Lannigou Gold Mine was evaluated by RQD and RMR methods,and it is believed that the rock mass of the mine is relatively broken,the integrity is not high,and the stability of the surrounding rock is low.After the site survey,it is found that the main reasons for the deformation and failure of the surrounding rock of the Lannigou Gold Mine are the large buried depth of the roadway,the poor surrounding rock conditions,the large section of the roadway,and the low support strength,and the asymmetric and heterogeneous structure of the surrounding rock of the roadway.The stability control of the surrounding rock of the roadway can be carried out by improving the stress state of the surrounding rock of the roadway,selecting the support of high-strength concrete-filled steel tube support,and optimizing the section of the roadway.(2)Based on the existing support methods and parameters of Lannigou Gold Mine,the characteristic curve of composite support of "anchor mesh shotcrete + steel tube concrete support" is analyzed.Comprehensively consider the role of time in the surrounding rock-supporting structure interaction process,summarize the three characteristics of the coupling process,namely,stress balance point,temporal and spatial evolution characteristics,and coupling deformation characteristics.(3)Theoretical calculations show that the bearing capacity of the concrete-filled steel tube support is 2.5-4.9 times that of the U-shaped steel support.The static loading numerical test shows that the U-shaped steel support under the same lateral pressure coefficient(0.8,1.2,1.5)is significantly stronger than the steel tube concrete support,and the maximum deformation of the U-shaped steel support is 62.1%,68.4%,and 70.5%,respectively.Numerical experiments of dynamic loading show that the real-time arrival position of the explosive stress wave on the bracket will produce an obvious stress concentration,and the real-time arrival position of the stress wave is the maximum stress position of the bracket.Under the disturbance of the blasting stress wave,the deformation of the two types of brackets shows obvious "regional characteristics",that is,the closer the bracket is to the blasting point,the greater the deformation,and vice versa.In the case of the same explosive amount,the final deformation of the concrete-filled steel tube support is always smaller than that of the U-shaped steel support,which shows that the concrete-filled steel tube support has a better load-bearing performance.(4)Taking the 30 mid-section sump as the engineering background,a targeted composite support scheme of "anchor mesh spray + straight wall three-core arch circular steel tube concrete support +reinforced anchor rod" is proposed.The test section and the non-test section of the support were compared and monitored.The two sides of the unframed section converged and the roof settlement values were 222 mm and 94 mm,respectively,and the two sides of the scaffold section converged and the roof settlement values were 38 mm and 19 mm,respectively.Decrease by 82.88% and 79.79%.The30 mid-section was monitored by the IMS microseismic monitoring system.The results showed that there were relatively few microseismic events in the concrete-filled steel tube support section,and the event aggregation was not obvious,indicating that there were fewer micro-fractures in the surrounding rock of the support section and no significant expansion and concentration.The coupling effect of surrounding rock and support effectively improves the overall bearing capacity of the surrounding rock.