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基坑开挖对临近地下管线的影响是城市基坑工程中经常遇到的一个问题,由于城市地下管线比较密集,往往出现上层是暖气管,下层是水管等双层地下管线的现象。针对以往研究没有考虑深基坑开挖对双层地下管线的影响,采用三维有限元法分析其管线变化规律,其中包括未加支撑、加支撑、支撑刚度、周围土体的弹性模量和支护结构变形等因素影响。计算结果表明,对于算例而言,加支撑与未加支撑相比,上下两管的竖直沉降和水平位移分别减小10%和70%左右;支撑刚度分别取2×108,4×108和8×108N/m,上下两管的竖直沉降和水平位移分别较前一工况减小1%和22%左右;土体弹性模量Es分别取4,8 MPa和16 MPa时,上下两管的水平和竖直沉降较前一工况均减小30%左右。
The influence of excavation on the adjacent underground pipeline is one of the most frequently encountered problems in urban foundation pit engineering. Due to the dense underground pipeline in cities, the upper layer is usually a heating pipe while the lower layer is a double-layer underground pipeline such as a water pipe. In the past, the influence of deep foundation pit excavation on double-layer underground pipelines was not considered. Three-dimensional finite element method was used to analyze the variation of pipelines, including unboosted, added support, support stiffness, elastic modulus and branch of surrounding soil Retaining structure deformation and other factors. The calculated results show that the vertical settlement and the horizontal displacement of the upper and lower pipes decrease by about 10% and 70%, respectively, compared with the unbraced support. For the example, the support stiffness is 2 × 108,4 × 108 And 8 × 108N / m respectively, the vertical settlement and the horizontal displacement of the upper and lower pipes decreased by 1% and 22% respectively compared with the previous condition. When the elastic modulus Es of soil was 4, 8 MPa and 16 MPa respectively, Both horizontal and vertical settlement compared with the previous conditions are reduced by about 30%.