The article was based upon analysis of the front-and-back surface vibration velocity of the working surface by monitoring the blasting operation at hidden digging section of Jiaozhou Bay cross-harbour tunnel in Tuandao road exit ramp. Research shows that the maxim-um value of the surface blasting vibration velocity appears on the front and back of the ground ,raging from 2 m to 7 m ,just above the working surface instead of the ground just above of the working surface. However, the surface vibration velocity generates behind the working surface was 1.2 to 1.4 times greater than the one generates at the front of the working surface. The front-and-back surface vibration velocity tends to be flattening on the ground which was more than 20 m away from the working surface, just above it.
In this paper, the background is Qingdao Cross-harbor Tunnel Guide Line Project. The research on blasting vibration peak velocity was carried out by monitoring a 6-layer brick-concrete building. According the research, we discover that vibration peak velocity in the vertical direction reaches a maximum on the roof of the building. In the horizontal radial and tangential horizontal direction, the maximum appears at the 1st or 2nd floor. Third, within certain distance from blasting center, the value of horizontal vibration peak velocity is larger than vertical vibration peak velocity.
Contraposed the hydration heat of large volume concrete, based on the introduces of raw material, the effect of fly ash mix amount in large volume pile cap concrete was mainly analyzed combined with project case of Yellow River Bridge in Baotou-Shulinzhao Highway. Moreover the temperature and temperature stress in different mix amounts were analyzed by the finite element software to confirm the appropriate mix amount of fly ash and the mix proportion of concrete. Finally, the consequence of the large volume pile cap temperature control was certified by the practice of construction.
In this paper, the background is Qingdao Metro Line 3. Combined with the existing theoretical and on-site construction experience, the defined method of shallow tunnel and the difficulty of construction in the subsurface excavation of urban shallow tunnel are discussed and analyzed. In the subsurface excavation of urban shallow tunnel, it is important to choose appropriate excavation method and right way of tunnel support.
According to the tunnel blasting vibration test at Kiaochow bay Cross-harbor Tunnel Guide Line Project, the regulation of the tunnel vibration velocity has been studied. Based on the analytical results, this paper finds that the change regulation of vertical, horizontal radial and tangential vibration velocity as the different distances from the work face. The tunnel vibration velocity of the rear work face is greater than the unexcavated area. The peak value of the rear work face is 2-2.5 times as large as that of the front work face, vibration velocity of the front work face attenuates gently. The paper figures out the relationship between vibration velocity and distance from sensor to the work face, which can offer a reference to similar studies.
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