The Construction Effect And Control Technology In Shallow Tunnel Of Soft Surrounding Rock

With the development of traffic construction in our country, highway tunnel,railway tunnel near gob emerge continuously. How to ensure the safety ofconstruction and operation in the mined region, it had become a new task faced inengineering field. When the new tunnel in gob area, the risks were mainly:(1) goafrock plate or rock column instability even tunnel collapse were caused by the newexcavation construction vibration;(2) the existence of mined out area changed theoriginal distribution of stress state and the tunnel structure stress was not even, easilycausing new tunnel local crack;(3) the goaf long-term residual deformation wascaused by tunnel uneven subsidence, seriously influencing the train running safetyand durability of tunnel structure. Therefore, this paper regarded the Ming and QingTang tunnel of Lou Shao railway expansion renovation project as the engineeringbackground. Based on the construction control technology through the existingmining goaf tunnel main research work was as follows:(1) According to the Ming and Qing Tang tunnel exploration data, new tunnelcame across concealed goaves and open gobs. For the analysis of tunnel goavesimpacting on the tunnel construction effect, this paper added tunnel stored right andupper gob and tunnel stored right open mined area, from the displacement around thetunnel, surface subsidence, supporting internal force and plastic zone distribution fouraspects. Through comparison and analysis, combining with the actual constructionconditions, this paper determined the construction method for the Ming and QingTang tunnel. After determining construction method, and analyzing the differentdistance under the goaf from tunnel excavation simulation aspect by using thismethod, this paper determined whether this method could continue to apply.(2) This paper evaluated the stability between goaf and the tunnel by usingcatastrophe theory. By studing between the total po tential energy between goaf andtunnel rock, establishing strata catastrophe models of instability, this paper derivatedcalculation formulas of satety distance and mechanical conditions of instability in thecase of existing concealed mining empty area under the tunnel and open goaf up thetunnel According datas, this paper calculated minimum safety thickness of roof andcompared numerical simulation results. This paper derivated calculation formulas of satety distance and mechanical conditions of instability considering dynamic loadsinfluence. This paper derivated calculation formulas of satety distance and mechanicalconditions of instability considering gobs which might arise and rock similar to rockpillars between the tunnel. This paper provided a theoretical basis for the tunnelengineering design and construction.(3) According to the engineering features of the Ming and Qing Tang tunnel, thispaper summarized the tunnel construction control technology with the goaf in a safedistance from the tunnel, and with the goaf near from the tunnel. This paper alsoconsidered gob treatment, and reinforcement measures. From the above three aspects,this paper provided suggestions guaranting for the smooth construction of this project.