Taking the deep foundation pit of the west ramp of Xinjian Rd.of Shanghai Beiheng Passage as the object,under the unfavorable condition that the adjacent large-diameter tunnel of the foundation pit is only 1.10～2.77 m,the main measures for controlling the micro-deformation of the foundation pit are put forward:strengthening the foundation pit foundation,strengthening the foundation pit cushion,increasing the steel purlin with local diagonal bracing,reinforcing the water stop of the enclosure wall joint,standardizing the earth excavation,using the support servo system and branch protection.At the same time,the main measures for tunnel protection are put forward:increasing shear pins in segment structure,improving the reinforcement of segment structure,using mouth shaped parts for construction and backfilling with plain concrete on both sides,embedding steel plates,improving the quality of synchronous grouting and adding secondary grouting holes.Through the micro-deformation control of foundation pit excavation and tunnel protection measures,the safe implementation of deep foundation pit engineering adjacent to large diameter tunnel can be realized.
deep foundation pitlarge diameter tunnelclose rangemicro-deformation control
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