Research On The Ground Settlement Caused By The Shield Construction And The Protection Of The Adjacent Buildings

Although the shield construction technique has developed greatly, it will inevitably cause the stratum perturbation, so as to distort soil and cause the surface subsidence, and distory the close adjacent buildings, thus the initiation environment earthwork problem will appear. This phenomenon is especially remarkable in the soft soil. Taking Wuhan Yangtze River tunneling key technologies research project as the background, the dissertation studies the effect of the slurry shield construction to the ground and buildings and protection measures in the full scales.This dissertation's innovation including five aspects as follows: First, taking Guangzhou subway two lines Yue San shield sector project, the NanJing subway first phase 15 sign shield sector project and the Wuhan Yangtze River highway tunnel shield project as the object, it studies the lasted subsidence rule during the shield construction period to discover the reason and mechanism of the ground dislodgement in the weak stratum shield law construction. Second, taking the Wuhan Yangtze river highway tunnel as the project background, the two-dimension and the three dimension finite element numerical simulations are conducted with considering or without considering the building in view of the different operating mode. The two-dimension analysis indicates that it may be used to forecast which spots are the most dangerous spots during the whole process. The tunnel burying depth is smaller than in the 1.0D situation, the area of the settlement is less narrow, but the value of peck settlement is larger. Regarding to the slurry shield tunnel, the burying depth is smaller, it means that the construction parameter turning band is small, the construction is more disadvantageous, the ground is easier to brave the thick liquid. The three dimension numerical simulation indicates that building's existence does not influence badly on the plastic area's size around the tunnel. It indicates that the next tunnel excavation the nearby soil body has certain influence on two tunnels. Considering that building's existence, crosswise subsider shape obvious different, the subsider shape smoothly continuously has the zigzag sudden change. The dangerous time of the building longitudinal is around the tunnel excavated surface passes in the AD scope. For the three dimension model, the experimental result and the field test result are quite close with the related parameter adjustment. Third, the building protection system has been established in order to prevent to influence on the neighboring building, first it is for tunnel excavation to take the driving measure. The shield machine mud quality, the slurry pressure, the shield advance the pressure, the tunneling speed, the synchronized slurry and the attitude control and so on in various aspects should be controlled increasingly. However, even if when taking tunnel excavation measure is still to worry that the building was affected adversely, the corresponding reinforcement measure must be taken in the close building. Above The theory protection system applies in the historic building Luci and the Wuhan Institute of Technology electricity and education building, and makes the good construction progress and the social efficiency.Fourth, in view of the Wuhan Yangtze River tunneling, referring to the domestic and foreign project experience, the dissertation proposes protection standard of the Wuhan Yangtze River tunnel normal neighbor buildings, and double controls standard in view of the historic building protection-the building itself changes (crack) and the building subsidence as well as the surface subsidence, applies successfully in the project. Fifth, it conducts the research to the cross section subsider to indicate that the Peck formula still might use for the Wuhan stratum, proposes the superpueition technique for settlement cough of the double tunnel, which solves its subsidence maximum value to vary from two tunnel centers, moreover the subsider had the asymmetrical situation frequently, for the Peck formula, it is an improvement and proposes firstly the subsidence and the appendix subsidence caused the trough width parameter design proposal value are 0.45 and 0.5, separately.Above research results will play an important role in the river shield tunnel's success penetration, protection of the Luci, the construction and the monitor of the following projects. It also will offer important reference to the similar projects in the design, construction and the measurement.