为加快双线地铁隧道施工,采用2台盾构机同时开挖,盾构横向间距不变情况下,纵向间距过近会加剧对土体的扰动,影响地表建(构)筑物安全。以武汉地铁三号线为工程背景,选取双线平行隧道盾构同向推进为研究对象,采用现场监测和数值模拟计算方法,综合分析盾构开挖时隧道横向、纵向地表变形特征,揭示双线平行隧道盾构同向推进时的纵向相互影响规律。结果表明:数值计算结果与现场监测数据相吻合;盾构通过后地表形成沉陷槽,隧道拱顶上方地表变形最大,距离隧道轴线越远,地表变形越小;开挖过程中盾首上方隆起值达到最大,盾构穿过后沉降迅速增加,最终趋于稳定;双线地铁隧道盾构同向推进中,盾构的二次扰动加剧了地表最终变形量,盾构纵向间距对地表最终变形量没有影响,随着盾构纵向间距增加,地表总体沉降速率减缓,当盾构纵向距离大于50 m时较为安全可靠。研究成果旨在为今后的地铁隧道安全快速的施工提供依据。

In order to speed up the construction of double line subway tunnel,two shield machines are used in the excavation at the same time.Under the condition of invariable transverse spacing of the two shields,small longitudinal spacing will aggravate the disturbance of surrounding soil and affect the safety of surface building(structures).In this paper,with Wuhan Metro line 3 as engineering background,the characteristics of transverse and longitudinal surface deformations of shield tunnel excavation are analyzed through field monitoring and numerical simulation,and the regularity of longitudinal influence of double-line parallel tunnel excavated in the same direction is revealed.Results show that the numerical results accord with the field monitoring data;surface subsidence trough forms after the shield passes.The surface deformation above the tunnel vault remains the biggest,and the farther away from the axis of the tunnel,the smaller the surface deformation reaches.In the process of excavating,the surface uplift value above the front of shield reaches the maximum;the surface settling velocity increases rapidly after the shield passes and finally tends to be stable.In the process of shield excavating in same direction of double line metro tunnel,the secondary disturbance of shield contributes to the final surface deformation,but the longitudinal spacing of shields has no effect on the final surface deformation.With the increase of longitudinal spacing of shields,the total surface settling velocity slows down.It is safe and reliable when the longitudinal spacing of shields exceeds 50 m.The research result of this paper is expected to provide a basis for the safe and rapid construction of subway tunnels.