盾构隧道施工对管片环和地表沉隆变位的影响研究

Analysis on the Influence of Shield Tunnel Construction to the Segment Ring and Ground Movement

结合某地铁区间盾构隧道所处围岩地质状况,引入荷载释放系数,采用三维有限元法对盾构隧道施工所引起的隧道应力场和位移场、管片环整环变形、地表三维沉隆变位与横、纵向沉隆曲线分布变化规律进行了深入研究,得到如下结论:(1)隧道施工将引起呈带状分布于隧道拱顶的较大管片环应力,且该应力随施工进程增幅较小。(2)管片环最大和最小位移分别呈带状分布于盾构隧道拱顶和拱底,且随着掌子面的前行略有增加并渐趋稳定。管片环呈横向变形趋势发展,拱顶下沉量最大,拱腰外扩量次之,而拱底隆起量最小。(3)随着掌子面的逼近,前方约15m处地表形成隆起,随后下沉且该沉降速率较大,两侧土体向隧道中线移动,地表沉降槽较大但渐趋稳定。

Aimed at the surrounding soil geology condition which sectional metro shield tunnel lies, 3D FEM method was adopted in the research of tunnel stress and strain distribution, segment ring deformation, 3D ground movement and sectional（longitude） settlement curves conduced by shield tunnel construction with the introduced load release factor. Form the study, these conclusions were achieved ： （ 1 ） The larger circumferential stress of segment ring caused by tunnel construction lies in tunnel vault and presents zonal distribution. These stresses increase slightly and limitedly in the course of excavation. （2） The maximum displacement which takes on zonal distribution locates in tunnel vault and the minimum displacement locates in tunnel intrados. With tunnel excavated, these displacements increase slightly and drive to invariant gradually. Deformation of segment ring is transverse and vault settlement is the utmost, hance displacement takes the second place and intrados uplift is the least. （3） With the excavate approaching,the front ground surface（ about 15m） is upheaval in the beginning and sinking subsequently. Both sides soil move to center of tunnel. Ground surface settler is rather large and goes to invariant gradually.