基于统一解的近距离双线平行盾构地面沉降计算

Calculation of Ground Settlements Induced by the Construction of Twin Parallel Shield Tunnels with Small Intervals Based on the Uniform Analytical Solution

文章提出盾构法隧道统一土体移动模型二维解的修正公式,并利用该公式计算近距离条件下双线平行盾构施工产生的总的地面沉降。该方法适用于双线隧道近距离工况,采用近距离界定系数C=L/(h+R)≤0.66作为本文公式适用条件,当C>0.66时本文公式不再适用;当C≤0.66时,沉降曲线呈"V"形;当0.66<C≤0.79时,沉降曲线呈"V-W"形;当C>0.79时,沉降曲线呈"W"形。算例分析结果表明:当C≤0.66时,本文方法计算得到的地面沉降值与实测值非常吻合;近距离双线平行盾构施工引起的地面沉降曲线符合正态分布规律,但最大沉降值有时会偏离中轴线。

A corrected two-dimensional analytical formula is presented based on a uniform soil mass movement model for shield tunnels, and it is used to compute the total ground settlements caused by construction of twin paral- lel shield tunnels with small intervals. The proposed formula is applicable for the approaching construction of twin parallel tunnels under the condition of a relative horizontal distance coefficient C=L/（h＋R）≤0.66, while it is inapplicable if C is larger than 0.66; the settlements curve is a ＂V＂ shape if C is lower than or equal to 0.66, it is a ＂V-W＂ shape if C is larger than 0.66 and lower than or equal to 0.79, and it is a ＂W＂ shape if C is larger than 0.79. The calculation example analysis show that： the ground settlements calculated by the proposed formula agree well with the measured values when C is lower than or equal to 0.66; the curve of ground settlements caused by approaching construction of twin parallel shield tunnels conforms with the normal distribution law but the maximum settlement sometimes may deviate from the central axis.