地面堆载引起的邻近地铁隧道变形分析

Deformation Analysis of Adjacent Subway Tunnel Induced by Ground Surcharge

为研究地面堆载引起的地铁隧道变形,首先采用Boussinesq基本解计算地面堆载作用在隧道上的竖向附加应力,再将隧道简化为搁置在利夫金地基上的Timoshenko长梁,考虑土介质的连续性和隧道剪切效应,给出地面堆载引起的邻近地铁隧道变形的计算公式,然后将公式计算值与使用EulerBernoulli梁模型计算结果和工程实测数据进行对比,最后对隧道变形影响因素进行了分析。结果表明:使用Euler-Bernoulli梁模型计算明显高估了隧道沉降量和内力,本文计算方法结果更精确;相对于堆载宽度,堆载长度的变化对隧道变形的影响更显著;距地面堆载中心的水平距离较小时浅埋地铁隧道沉降较大;隧道沉降量随地面堆载密度增大而逐渐增大,但堆载对隧道的影响范围不受其影响。

In order to study the deformation of subway tunnel caused by ground surcharge,first of all,Boussinesqbasic formula was used to calculate the vertical additional stress induced by ground surcharge on the tunnel.Secondly,considering the soil medium continuity and tunnel shear effect,the tunnel was simplified into a Timoshenko long beambased on the Rifkin foundation to give out a deformation calculation formula of the adjacent subway tunnel caused by theground surcharge.Thirdly,the results of the formula and from the Euler-Bernoulli beam model were compared with theengineering measured data.Finally,the influencing factors of the tunnel deformation were analyzed.The results indicatethat both the tunnel settlement and internal force are obviously overestimated by the use of the Euler-Bernoulli beammodel,while the results by the calculation method of this paper are more accurate.The surcharge length has a moresignificant effect on the tunnel deformation than that by surcharge width.The settlement of the shallow buried subwaytunnel is large when the horizontal distance from the ground surcharge center is small.With the increase of the surchargeload,the settlement of the tunnel gradually increases,but it has little effect on the impact range of the tunnel.