深厚砂层中深基坑开挖引起临近地铁变形及控制方法研究

Deformation and Control Methods for the Adjacent Subway Induced by Deep Excavations in Deep Sand Layers

在深厚砂层地区,在运营中的地铁隧道结构外一定距离开挖深基坑,必须严格限制隧道结构变形,深基坑的设计施工和监测需要极高的要求。针对具体工程实例,采用现场监测和数值分析的方法,研究地铁隧道结构与基坑边不同距离情况下其变形规律,结果表明,采用咬合灌注桩结合混凝土内支撑的支护结构满足变形控制要求,且地铁隧道距离基坑越近,其水平位移和竖向位移越大,其中,地铁隧道结构顶实测最大竖向位移为5.65 mm,最大水平位移为4.60 mm。在进行基坑设计时应按不同距离,有针对性的局部加强支护结构刚度,或者对地铁隧道结构侧土体加固处理。

In the area of deep sand layer,the deep excavation must be performed at a safe distance from the active subway tunnel structure to ensure the operation safety of the subway.The deformation of the tunnel structure must be strictly controlled.The design,construction and monitoring aspects of the deep excavation have extremely high requirements.Focused on the specific engineering examples,the deformation patterns of the subway tunnel structure at different distances from the deep excavation are studied by using the methods of on-site monitoring and numerical analysis.The results show that the supporting structure with the secant pile wall combined with the concrete internal support meet the deformation control requirements.Moreover,the closer the subway tunnel is to the deep excavation,the greater the horizontal and vertical displacements.Among them,the measured maximum vertical displacement of the subway tunnel roof is 5.65mm,and the maximum horizontal displacement is 4.60 mm.In the design of the deep excavation,the stiffness of the supporting structure should be strengthened locally according to different distances,or the soil improvement on the side of the subway tunnel structure should be performed.