Study On Construction Technology For Caishenliang Extra-Long Express-Highway Tunnel

The paper researches on the major technologies of constructing tunnels in terms of Caishenliang Tunnel's geology, physiognomy and topography.Caishenliang Tunnel, which is about 5,000-meter long, is one of the projects from Fengjie to Yunyang, which is part of the high way from Chongqing to Yichang.The construction of the tunnel began on May 8th,2006 and ended on October 31st,2008, lasting 30 months. In the process of the construction, the application of GPS solved the tough problems such as laying the regular geodetic chain in mountain areas of extremely complicated physiognomy and topography. Moreover, TSP performed the work of the advanced prediction of long-term and long-distance geology, provided the dynamic information of the working face rock mass, which was applied to guiding the construction and prevented the geological disasters.There were no silos and accessory laneways in the tunnel, ventilation seemed impossible in 2,500- meter construction of cut method, so two forced ventilating facilities which were 2×110kw were used in 1,500-meter place. And making use of the vehicles and people adit levels between left and right tunnels to add jet flow blowers and set 3 water curtains with 30,50 and 80 meters to the working face respectively. The water-curtain machines were installed on the half cutting face.One water-curtain machine was installed on each side of the water curtains. They were turned on 5min ahead of explosion and turned off 30min after it in order to speed up the settling of harmful kernel like dust and increase the ventilating efficiency. Thus, the health of workers could be guaranteed and the constructing efficiency and profits could be raised. Two big-fraction liners were designed in the tunnel and by widening the jack horse and changing under formworks, it not only guaranteed the construction quality, accelerate the process, but also cut down on the expenditure. The Tunnel cut 2, 500-meter long, three- phase-five wire system with 10 kV was applied to the construction and a transformer was installed in the 1,500-meter place. Therefore, the tremendous dropping of voltage caused by long-distance transporting of electricity into the tunnel has been avoided.Based on the previous technologies, especially GPS, TSP, adding jet flow blowers and laneway ventilation, the safety, quality and progress of construction are guaranteed. Furthermore, the ventilation helps to protect the workers and reduce the working intensity and project expenditure, which is a good example for other similar tunnel constructions and huge road tunnel constructions.