Research on Construction Control Technology for Railway Tunnel Underneath Passing Existing Expressway Tunnel

Research purposes: The purposes are to ensure the construction safety of newly-built tunnel and make(existing) road open to traffic usually while the newly-built tunnel underneath passes existing(tunnel) nearby.Research methods: According to the real construction situation of Guantouling Tunnel underneath passing existing(expressway) tunnel on Wenzhou-Fuzhou Railway Line and in combination with the research achievements at home and(abroad),and current state codes,the analysis and research have be made on construction scheme for newly building a tunnel around cross point and on measures for monitoring and measuring the existing expressway tunnel based on the (analysis) of integrity level of existing tunnel and construction countermeasures.Research results: Several construction techniques and their relative parameters and control standard are presented.Research conclusions:(1) More attention should be paid to the serious harm probably caused by blast vibration(nearby).Therefore,it is necessary to evaluate the lining strength of existing tunnel,cavity distribution behind lining and(earthquake) resistant behaviour of lining,to work out the basic control standard for blast vibration and make research on rational blast parameters before construction of intersection of Guantouling Tunnel.(2) When the working face of newly-built tunnel approaches to hole diameter of 3-4 times from cross point,the monitoring and measurement in the(existing) tunnel should be done well.With the analysis result of monitoring,the adjustments should be made rationally of(excavation) way,blast parameters and method of ignition in order to ensure the safety of the tunnel.(3) After finishing the construction of intersection,the safety should be re-evaluated to tunnel lining structure(near) the cross point of(existing) tunnel in order that the tunnel will not be damaged with time passing by.