论文部分内容阅读
考虑基坑坑底与侧壁卸荷应力以及基坑围护结构的影响,建立基坑开挖力学计算模型。基于Mindlin应力解公式,推导得到基坑开挖引起的临近既有地铁隧道的附加荷载计算公式,并对基坑尺寸改变、隧道位置改变以及加固控制措施这3方面的影响因素进行分析。算例分析结果表明:(1)当隧道位于基坑旁边时,基坑侧壁卸荷作用对隧道的影响非常大,坑底卸荷作用则影响较小,但当基坑开挖深度较浅时则影响会增大;(2)在水平向隧道受到朝向基坑一侧的拉力,数值较大。在竖向隧道受到竖直向上的拉力或向下的压力,数值小;(3)s,B,d及?这4个影响因素改变对隧道的水平向受力影响最大,L改变的影响次之,h改变的影响最小;(4)d改变对隧道的竖向受力影响最明显,其次为s,B改变的影响,其余影响因素改变均不明显。
Considering the unloading stress at the bottom and sidewall of the pit and the influence of the retaining structure of the foundation pit, a calculation model of foundation pit excavation mechanics is established. Based on the Mindlin stress solution formula, the formula for calculating the additional load caused by the excavation of the existing subway tunnel is deduced. The influencing factors of the pit size change, tunnel position change and reinforcement control measures are analyzed. The case study shows that: (1) When the tunnel is located beside the foundation pit, the unloading effect of the sidewall of the foundation pit has a great influence on the tunnel and the effect of unloading at the bottom of the pit is small. However, when the excavation depth is shallow When the impact will increase; (2) in the horizontal direction to the tunnel by the side of the pit pull, a larger value. In the vertical tunnel, the vertical upward tension or downward pressure is small; (3) s, B, d and φ have the most influence on the lateral horizontal force of the tunnel; (4) The influence of d change on the vertical stress of the tunnel is the most obvious, followed by the change of s and B, and the other influencing factors are not changed obviously.