Research On The Identification And Assessment Of Major Hazards During The Metro Construction

While metro construction is carried out continuously, it is necessary to conduct the identification and assessment of the major hazards during the metro construction to avoid serious consequences. At present, although there are many research achievements on the major hazards, but little targeted in the metro construction. According to this, it is great significant to promote an identification and assessment on the major hazards that could arise to ensure the security of metro construction.The hazards factor form of metro construction is built based on the analysis of the developed mechanism in metro construction. The form includes three accounts of the hydro-geological and surrounding environment, the construction techniques and equipment and facilities, and the construction management and decision-making. Then, the interval between Yingwan bay station and May 1 Square station of the Metro Line 2 of the Changsha Metro is choosed as the research object. Shield is selected as the construction method of river tunnel. The major hazards is identified by use of the combination of WBS and RBS, and then the identification forms of hazards factors of the two stations of Yingwan bay and May 1 Square, which covering three aspects of hydrology, environmental technology and the surrounding factors, are established. Combing aforementioned construction method and the identification forms, the interval hazards evaluate system of Metro Line 2 of the Changsha Metro is built, and by evaluation, it could be obtained that the major hazards exist in the shield tunnel construction pass in and out turnover, in advance, and through special sections. Furthermore, using the improving LEC method, the hidden hazards are chiefly as follows: shallow overburden, inappropriate soil pressure, excessive settlement of the earth's surface, the excessive building tilt, the pier tilt, the uneven caps sedimentation, and the damage of the electric line and electricity transformation line. Particularly, the measures of the metro safe construction are promoted.