Design practice and key technology for the foundation pit in complex geology and sensitive environments

Abstract:

The deep and large foundation pit project of an international financial building in Shanghai is adjacent to the operating rail line interval with the shortest distance of only 7.87m on the north side， and the clearance of 2.0 to 3.0m from the pipe ditch of World Expo on the south side. Because of the high sensitivity of the surrounding environment， the deformation control of the foundation pit is quite demanding； meanwhile， the project is located on the bank of the Huangpu River. The shallow layer at the site is a typical silty soft soil layer， while the lower part is a soil layer rich in confined ground water. Moreover， the micro-confined aquifer is connected to the first and second confined aquifers， and the sealing curtain cannot cut off the confined aquifers. All these factors constitute complex geological conditions. Considering the situation， the project adopted various technical measures. The final measurement results showed that the maximum deformation of the tunnel is 6.52mm， and the maximum deformation of the pipe ditch is 15.3mm， which meet the deformation control requirements， ensuring the safe operation of the tunnel and the pipe ditch.