深基坑开挖施工对邻近地铁结构受力性状的影响

Influence of Deep Foundation Pit Excavation on the Mechanical Behavior of the Adjacent Metro Structure

以天津市某邻近深基坑工程的既有地铁线路为例,结合现场实测数据,采用荷载-结构法建立地铁隧道结构三维有限元模型,对地铁隧道结构设计状态与当前状态下的受力情况进行模拟,分析隧道结构、螺栓、钢筋受力状态。研究结果表明,工况1、工况2下,最大拉应力为:隧道拱顶内侧混凝土分别为2.43 MPa、2.98 MPa,隧道拱腰外侧混凝土分别为2.42 MPa、2.45 MPa,小于混凝土极限抗拉强度3.1MPa,未受拉破坏;环向螺栓分别为216.8 MPa、238.4 MPa,纵向螺栓分别为68.3 MPa、65.3 MPa,均小于螺栓的屈服应力400 MPa,未发生屈服;钢筋分别为236.0 MPa、275.6 MPa,均小于钢筋的屈服应力335MPa,未发生屈服。

The construction of deep foundation pit may cause the deformation of its adjacent existing metro structure,to a certain extent,affect the mechanical properties,then it may have someimpacts on the normal operation of the metro lines. By taking one existing metro line which adjacent the deep foundation pit in Tianjin as an example,the load-structure method is adopted to establish a three-dimensional finite element model of the metro tunnel structure to simulate the stress condition under the design state and the current state,the stress state of the tunnel structure,bolt and steel bar are analyzed. The results show that the maximum tensile stress of the inner concrete of tunnel vault is 2.43 MPa and 2.98 MPa,the tunnel arch waist concrete is 2.42 MPa and 2.45 MPa,less than the ultimate tensile strength of concrete 3.1 MPa,there is no tensile failure of the concrete,the maximum tensile stress of the circumferential bolt is 216.8 MPa and 238.4 MPa,and the longitudinal bolt is 68.3 MPa and 65.3 MPa,all of them are less than the yield stress of the bolt 400 MPa,the maximum tensile stress of the steel bar is 236.0 MPa and 275.6 MPa,they are less than the yield stress 335 MPa,and they don＇t yield.