双线盾构长距离穿越深基坑底部对基坑围护侧移及内力的影响

海地铁10号线同济大学站-国权路站双线盾构长距离平行穿越下立交深基坑,穿越距离为630m,隧道与下立交基坑围护净距约2.0 m,施工现场环境复杂,盾构施工可能导致下立交深基坑围护结构发生侧向位移并产生附加内力。采用三维数值方法,模拟分析在基坑底板浇筑与未浇筑等情况下盾构施工对基坑围护结构侧移及内力影响的规律。分析表明:在底板施工后进行盾构施工,盾构施工引起基坑开挖面以上的围护侧移量较少,但底部侧移量变化非常明显;随着围护结构插入深度的增大,盾构施工引起基坑围护底部的弯矩值有增加的趋势;在底板施工完成的情况下,双线盾构穿越下立交基坑将致靠近基坑底板位置处的弯矩值由正弯矩逐渐变为负弯矩。数值计算较好的指导了实际工程的施工。

THE EFFECT ON LATERAL DISPLACEMENT AND INTERNALFORCE OF FOUNDATION PIT SUPPORT CAUSED BY DOUBLE-TUBE SHIELD LONG-DISTANCE PASSING THROUGH UNDER DEEP FOUNDATION BOTTOM

The double-tube shield tunnel from Tongji University to Guoquan Road metro station which passed longdistance parallel through the bottom of the under Crossing foundation finally caused the lateral displacement and additional internal force of foundation pit support,the passed through distance is 630 m,the distance between the tunnel and the diaphragm wall is about 2. 0m,the environment of construction is complex. By making use of threedimensional finite element analysis,the effect of shielded construction on the lateral displacement and internal force of the foundation pit support was analysod on the conditions of the bottom floor finish and the bottom floor did not finish.The analysis shows that the lateral displacement above the excavation surface caused by shield tunnel is less,however the lateral displacement under the excavation surface increases obviously; With the increase of the inserted depth of foundation pit support,the foundation pit support moment is creasing. When the bottom floor finished,shield tunnel passed through the under Crossing foundation,the moment near the bottom of foundation pit becomes negative moment gradually from positive moment. The analysis results is a very good guidance to the project construction.