基坑开挖诱发的周边土体位移将会对邻近管线产生不利影响。考虑基坑开挖的空间效应及管线的空间分布,将邻近管线视为Pasternak地基上的Euler-Bernoulli梁,采用三维影像源法提出了预测基坑开挖引起邻近管线附加水平变形的解析方法,并利用已有案例验证了该方法的合理性。结果表明:①管线总的水平变形主要由邻近并平行于管线的围护墙变形诱发产生,两侧的围护墙变形对开挖范围外的管线水平变形有较大影响。②针对管线的不同空间分布,通过定义的管线水平变形安全系数可预测基坑开挖对管线水平变形的不利程度,同时通过安全系数等值线得到了基坑开挖对管线水平变形的影响区域。③当管线与围护墙距离在0.75H(H为基坑开挖深度)内时,安全系数随着管线埋深的增加先减小后增大,且当管线埋深约为1.0H时管线的安全系数最小;当管线与围护墙距离超过0.75H时,安全系数随管线埋深增加而增大。
Abstract
Excavation of foundation pits can cause adverse effects on adjacent pipelines due to the displacement of the surrounding soil. An analytical method for predicting the additional horizontal deformation of adjacent pipelines caused by excavation is proposed using a three-dimensional image source method. Nearby pipelines are treated as Euler-Bernoulli beams on a Pasternak foundation in consideration of the spatial effect of excavation and the spatial distribution of pipelines. The validity of the proposed method is demonstrated through existing cases. Results indicate that the total horizontal deformation of pipelines is primarily induced by the deformation of retaining walls that are adjacent and parallel to the pipelines. The deformation of retaining walls on both sides also significantly impacts the horizontal deformation of pipelines outside the excavation area. The adverse effects of excavation on pipeline's horizontal deformation can be predicted through defining a safety factor and considering different spatial distributions of pipeline. The influence zone of excavation on pipeline deformation can be obtained through plotting contours of the safety factor. When the distance between the pipeline and the retaining wall is within 0.75H (where H is the depth of foundation pit excavation), the safety factor first decreases and then increases with the increase of pipeline's burial depth. The safety factor reaches its minimum when the pipeline is buried at a depth of approximately 1.0H. When the distance between the pipeline and the retaining wall exceeds 0.75H, the safety factor increases with the increase of pipeline's burial depth.
关键词
基坑开挖 /
空间效应 /
邻近管线 /
影像源法 /
安全系数等值线
Key words
excavation /
spatial effect /
adjacent pipeline /
virtual image method /
contours of safety factor
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