地铁车站明挖基坑近接互通式立交桥施工稳定性分析

临近建筑物的存在通常会影响基坑的开挖及稳定性。以青岛某基坑开挖案例为研究对象,在基坑的水平方向上,其与已经建成的高架桥桥和匝道之间的距离非常接近,假如没有足够的防护措施,在基坑的挖掘过程中,将会对已经建成的桥梁和匝道造成一定的冲击,结果会非常严重。该文采用有限元方法对基坑围岩变形、已有地基沉降和支护结构的稳定等进行详细研究,探讨基坑围岩的安全问题。计算结果表明,基坑内土的竖向最大位移量在数值上两侧不对称分布,最大垂直位移位于基坑AB侧壁处,位移约为12.36 mm且基坑的变形影响范围呈椭圆状分布;基坑水平位移在数值上为AB、CD侧不对称分布,最大水平位移出现在CD基坑大小约为6.40 mm,地表沉降及桥变形均在规范范围之内,因此,可以认为在基坑开挖的过程中,基坑和已有建筑物都是安全的。

The existence of adjacent buildings usually affects the excavation and stability of the foundation pit.A foundation pit excavation case in Qingdao,for example,is very close to the viaduct pier and ramp in the horizontal direction of the foundation pi.If there are no enough protective measures,it will have a certain impact on the already built bridges and ramps in the process of foundation pit excavation,and the result will be very serious.The deformation of surrounding rock of foundation pit,the settlement of existing foundation and the stability of supporting structure are studied in detail by finite element method,and the safety of surrounding rock of foundation pit is discussed.The calculation results show that the maximum vertical displacement of the soil in the foundation pit is asymmetrically distributed on both sides,the maximum vertical displacement is about 12.36 mm at the AB side wall of the foundation pit,and the influence range of deformation of the foundation pit is elliptical.The horizontal displacement of the foundation pit is asymmetrically distributed on the AB and CD sides,and the maximum horizontal displacement appears when the size of the CD foundation pit is about 6.40 mm,and the surface settlement and pier deformation are within the standard range,so it can be considered that in the process of foundation pit excavation,the foundation pit and the existing buildings are safe.