MECHANIC RESPONSE OF A SHALLOW-EMBEDDED AND DOUBLE-ARCH TUNNEL UNDER PARTIAL PRESSURES DURING CONSTRUCTION
-
摘要: 以江西某高速公路一浅埋偏压连拱隧道为背景, 用MARC有限元程序对其出口段进行了动态施工的三维数值模拟。系统研究了塑性区分布和发展、拱顶下沉、正应力与剪应力的集中和转移、中隔墙竖向应力随施工过程的变化规律。研究表明:1.非对称开挖是引起中墙偏压的最关键因素, 初衬和二衬的施作对改善中墙偏压作用不大, 对称开挖才是最有效途径; 2.在浅埋条件下, 拱顶下沉有随埋深增大而增大的趋势, 位移释放在开挖完成、支护之前就已经大部分完成。3.左右洞上台阶开挖后拱顶出现拉应力区, 是易坍方部位, 应超前或及时支护; 4.由于偏压作用, 山脊一侧边墙和中墙墙踵处塑性区更发育, 该侧更易失稳; 5.施工完毕, 隧道两侧边墙附近集中的压应力转移到二衬和仰拱上, 使二者成为应力集中部位, 从而改善了隧道围岩的受力状况。Abstract: Taking an expressway in Jiangxi province as the engineering background, the behavior of a shallow-embedded and double-arch tunnel with partial-pressure during construction is simulated.Several aspects, such as stress concentration and transfer, plastic zone distribution, vault displacement and change of vertical stress, (σy)of the mid-leading wall with construction are studied systemtically. The study indicates that :1) asymmetrical excavation is the key cause of partial pressure in the mid-leading wall and the construction of the first and second lining can not ameliorate the conditions greatly; 2) under conditions of shallow embedment, vault displacement increases with embedment depth and displacement mainly happens during excavation of tunnel before lining construction; 3)after excavation of the up-bench tunnel, pulling stress concentrates around the top arch and lining should be constructed promptly or beforehand; 4)as a result of partial pressure, when plastic zones around the side-wall and mid-leading wall heel, which are near the mountain ridge, are better developed; and 5) when construction finished, compressive stresses at tunnel side-walls disappear and are transferred to the inverse arch and second lining, making them concentrated by shear stress and normal stress and improving the stability of the tunnel.
-
Key words:
- 3D numerical simulation /
- partial pressure /
- vault displacement /
- plastic zone /
- stress concentration
-
图 3 左洞拱顶下沉与进洞距离关系曲线图
Figure 3. Curves of vault displacement vs.distance for the left tunnel
图 4 右洞拱顶下沉与进洞距离关系曲线图
Figure 4. Curves of vault displacement vs.distance for the right tunnel
图 5 左洞拱顶下沉与工况步关系曲线图
Figure 5. Curves of vault displacement vs.loadcases at different vault points for the left tunnel
图 6 右洞拱顶下沉与工况步关系曲线图
Figure 6. Curves of vault displacement vs.loadcases at different vault poins for the right tunnel
图 7 Lcase2-Lcase7-Lcase10-Lcase13剪应力集中云图(进洞20m)
Figure 7. Shear stress distribution around the tunnel during construction
图 8 Lcase1-Lcase7-Lcase11 -Lcase13正应力集中云图(进洞20m)
Figure 8. Normal stress distribution around the tunnel during construction
图 9 Lcase2-Lcase7- Lcase11- Lcase13塑性区分布云图(进洞20m)
Figure 9. Plastic zone distribution around the tunnel during construction
图 10 Lcase3-Lcase7-Lcase8-Lcase10-Lcase11-Lcase13中墙σy分布云图(进洞20m)
Figure 10. σy distribution of the mid-leading wall during construction
图 11 中墙横断面(距洞口20m)上部两侧节点σy 随工况步变化曲线图
Figure 11. Curves of σy vs.loadcases for the top mid-leading wall nodes on two sides
图 12 中墙横断面(距洞口20m)下部两侧节点σy随工况步变化曲线图
Figure 12. Curves of σy vs.loadcases for the bottom mid-leading wall nodes on two sides
表 1 模型材料力学参数一览表
Table 1. Mechanical parameters of model materials
-
[1] 蒋树屏, 胡学兵.云南扁平状大断面公路隧道施工力学响应数值模拟[J].岩土工程学报, 2004, 26 (2):178~182. doi: 10.3321/j.issn:1000-4548.2004.02.004 [2] 杜彬.长梁山隧道水平软弱围岩地段施工效应分析[J].岩石力学与工程学报, 2005, 24 (13):2357~2361. doi: 10.3321/j.issn:1000-6915.2005.13.026 [3] 金丰年, 钱七虎.隧洞开挖的三维有限元计算[J].岩石力学与工程学报, 1996, 15 (3):193~200. doi: 10.3321/j.issn:1000-6915.1996.03.001 [4] 邓建, 朱合华, 丁文其.不等跨连拱隧道施工全过程的有限元模拟[J].岩土力学, 2004, 25 (3):477~480. doi: 10.3969/j.issn.1000-7598.2004.03.031 [5] 丁文其, 王晓形, 李志刚, 等.龙山浅埋大跨度连拱隧道施工方案优化[J].岩石力学与工程学报, 24 (22):4042~4047. doi: 10.3321/j.issn:1000-6915.2005.22.007 [6] 赵玉光, 张焕新, 林志远, 等.双连拱隧道施工力学数值模拟与施工方法比选[J].广西交通科技, 2003, 28(4):25~30. http://d.old.wanfangdata.com.cn/Periodical/gxjtkj200304007 [7] 林刚, 何川.连拱隧道施工全过程地层沉降三维数值模拟[J].公路, 2004 (3):136~140. http://d.old.wanfangdata.com.cn/Periodical/gl200403034 [8] 吴俊强, 刘永华, 李围.浅埋偏压连拱公路隧道施工数值模拟分析[J].公路交通技术, 2005, (4):137~141. doi: 10.3969/j.issn.1009-6477.2005.04.044 [9] 申玉生, 赵玉光.高速公路双连拱隧道的中墙力学特性分析[J].地下空间与工程学报, 2005, 1 (2):200~204. http://d.old.wanfangdata.com.cn/Periodical/dxkj200502009 [10] 申玉生, 赵玉光, 张焕新, 等.双连拱隧道施工过程弹塑性有限元数值分析[J].岩石力学与工程学报, 2004, 23 (增2):4946~4951. http://d.old.wanfangdata.com.cn/Periodical/yslxygcxb2004z2049 [11] 赵阳, 王伟笔, 杨昌能.偏压浅埋连拱隧道施工过程的三维数值模拟[J].中南公路工程, 2005, 30 (2):181~184. doi: 10.3969/j.issn.1674-0610.2005.02.054 [12] 陈火红.MARC有限元实例分析教程[M].北京:机械工业出版社, 2002. [13] 陈建勋, 欧阳院平, 王明年.公路隧道复合式衬砌结构数值计算及分析[J].中国公路学报, 2006, 19 (2):74~79. doi: 10.3321/j.issn:1001-7372.2006.02.013 [14] 吴波, 高波, 索晓明, 等.城市地铁小间距隧道施工性态的力学模拟与分析[J].中国公路学报, 2005, 18 (3):84~89. doi: 10.3321/j.issn:1001-7372.2005.03.017 [15] 吴满路, 廖椿庭.大茅隧道地应力测量及围岩体稳定性研究[J].地质力学学报, 2000, 6 (2):71~76. doi: 10.3969/j.issn.1006-6616.2000.02.011 [16] 马秀敏, 彭华, 李金锁.新疆西部地应力测量在隧道工程中的应用[J].地质力学学报, 2005, 11 (4):386~393. doi: 10.3969/j.issn.1006-6616.2005.04.013 -
下载:
计量
- 文章访问数: 180
- HTML全文浏览量: 132
- PDF下载量: 4
- 被引次数: 0
