Study On The Leakage Mechanism And Key Technology Of Anti-Leakage Treatment Of Coal Mine Transport Roadway Under River Bed

Most underground projects inevitably cross water-bearing strata,and many underground projects also cross rivers and lake bottoms.Ensuring the safe construction and operation of these projects is always one of the major technical problems in the field of underground engineering construction.Water leakage disaster is one of the many forms of disaster,and also the most important form of disaster.Due to the complex and changeable engineering geology and hydrogeological conditions,different projects have their own characteristics and difficulties,and each project is specific and unique.Developing theoretical results and technical countermeasures for underground engineering leakage control that are both relevant and have popular application value according to these characteristics and difficulties is an important goal pursued by engineers and technicians.This paper takes Longtan coal mine in Qianfeng District,Guang’an City,Sichuan Province as the engineering background.The paper researches the mechanism of roadway leakage and the key technology of treatment by using theoretical analysis,indoor test,numerical simulation,field inspection,and other comprehensive research means for the problem of leakage prevention of transportation roadway constructed under the riverbed.This paper has achieved the following innovative results:(1)A risk evaluation model of leakage hazard in the riverbed subducted tunnel was established,and the determination of the risk level of leakage hazard in the whole area of the tunnel was realized accordingly.Based on TOPSIS decision theory,combined with subjective and objective weighting methods,17 judgment indexes affecting the risk evaluation of water leakage in the roadway were determined from the spatial relationship between river and roadway,surrounding rock condition and hydrogeological conditions,and then the risk level was divided into 5 levels to establish a risk assessment model for water leakage in the transportation roadway of coal mines under the riverbed and determine the risk level of leakage disaster in the whole area of the roadway accordingly,which laid a theoretical foundation for the determination of the treatment plan.(2)Based on the Harris distribution and the Druker-Prager strength criterion,the principal structure equations of the mechanical properties of the tunnel surround rock under the coupled flow-solid action were derived,and the size effect,anisotropy and seepage mechanism of the tunnel leakage under the coupled flow-solid action were investigated.Based on the Harris distribution and the Druker-Prager strength criterion,the principal structure equation of the mechanical properties of the tunnel surrounding rock under the coupling of the seepage field and stress field is derived,and the parameters in the principal structure equation are determined and calculated based on the field measurement data.The influence mechanism of the direction of the main structural surface of the roadway envelope on the seepage characteristics and leakage mechanism is analyzed through the flow-solid coupling calculation,which provides a calculation basis for the selection of parameters of the treatment plan.(3)The working performance and microstructure formation mechanism of cementitious grout containing fly ash were systematically investigated,and a set of zoned composite anti-leakage treatment plan with leakage interception at the bottom of the riverbed and grouting in the rock layer was proposed.Aiming at the leakage prevention problem of the transport roadway of the coal mine under the riverbed,according to the risk level of the roadway leakage and the leakage mechanism,a set of zoning composite anti-leakage treatment plan with leakage interception at the bottom of the riverbed and grouting in the rock layer is proposed.Meanwhile,it is found that grouting material mixed with fly ash can reduce the thixotropic area of the grout body,which can significantly improve the construction efficiency and water plugging effect,providing technical guarantee for the smooth implementation of the plan,realizing the effective plugging of the leaking water body and ensuring the construction and operation safety of the roadway.The relevant research results of this paper have been successfully applied in Longtan coal mine in Qianfeng District,Guang’an City,Sichuan Province,which has certain promotion and application value.