青岛地铁近距交叠隧道施工稳定性研究

为研究近距交叠隧道施工稳定性,以青岛地铁2号线枣山路—李村站区间隧道下穿3号线万年泉—李村站区间隧道为背景,通过数值模拟结合实测数据,分析交叠区地表变形、危险截面应力、变形规律及塑性区分布特点,由此可知:下穿施工后,地表变形从3.10 mm增至6.345 mm,由3号线沿线向交叠区中心延伸;当距交叠区中心超过40m时,地表变形影响可以忽略。交叠区截面受扰动影响最大,左右拱脚应力变化最明显,变化量为60、120k Pa,最大拉压应力分别为20 k Pa、2.1 MPa,小于衬砌所用混凝土抗拉抗压强度。另外,3号线最大变形位于交叠区隧道拱顶,2号线最大变形位于中夹岩拱顶,分别为11.77、9.85 mm;3号线拱底、2号线拱顶在交叠区产生变形突变,分别为5.67、8.64 mm,均在可接受范围内,并结合实测数据验证了数据分析的可靠性;2号线塑性区分布较大,上下隧道间岩柱基本处于完全塑性状态,拱脚及拱顶处塑性区分布最广,但左右线开挖塑性区并未贯通,塑性区半径控制在2.0 m之内,保证了施工的稳定。

Study on Construction Stability in Ultra-small Spacing Overlapping Tunnels of Qingdao Metro

Qingdao Metro 2 # and 3 # overlap between Zaoshan- Licun station and Wannianquan- Licun tunnel and the minimum vertical spacing is only 0. 2 m of a very small spacing category. To study construction stability,FLAC3 D is used for dynamic simulation to analyze surface deformation,stress characteristics,deformation characteristics and plastic zone distribution. The results show that after under-passing construction,surface deformation increases from 3. 10 mm 6. 345 mm,extending from the 3# to the overlap zone center. When the distance from the overlapping center is more than 40 m,surface deformation could be neglected. Section of overlapping zone is affected most by the disturbance,and the changes of stress of both arches are the most obvious with variation of 60 k Pa and 120 k Pa respectively.The maximum tensile and compressive stresses are 20 k Pa and 2. 1 MPa respectively,which are far less than those of the lining concrete. In addition,the maximum deformation of 3# and 2# of 11. 77 mm and9. 85 mm are respectively located on the vault and the folder rock. Mutations of 3 # dome( 2 # vault) in the overlapping area are 5. 67 mm and 8. 64 mm,falling within the acceptable range. Compared with the measured data,the reliability of the simulation data and the stability of the construction are analyzed and verified. Plastic zone of 2# is larger,the folder rock is nearly in a plastic state,the plastic zone of arch and vault turns to be the most widely area,but the plastic zones of the left and right lines do not run together,and the plastic zone radius is within 2. 0 m,the stability of the construction is ensured.