Analysis of Limit Support Pressure Due to Shield Tunnelling with a Shallow Overburden Under Seepage
-
摘要: 基于半承压水模型综合考虑土压盾构穿越渗透性地层时覆土层及下卧层的渗透性，推导了盾构穿越层中沿掘进方向的水头分布的解析解，将其与现有的二维渗流场的解析解结合扩展为相应的三维近似解，同时采用数值仿真得到稳态渗流条件下浅埋渗透性地层的主、被动破坏模式，建立了相应的柱体+弧形转角体模型，将前述三维渗流场引入该模型，通过力矩平衡法得到了相应两种极限状态下开挖面支护压力的计算公式，与既有结果进行对比，此计算方法更接近数值解. 研究结果表明：施工对开挖面前方渗流场的扰动基本局限在三倍洞径以内，主、被动极限支护压力的值随水头差的增大均线性增加，盾构直径和水头差是影响主动极限支护压力的主要因素，拱顶埋深与盾构直径是影响被动极限支护压力的主要因素；实际施工过程中，支护压力值应尽可能接近水土分算下的土体原始地层侧压力值，并在其附近（最好在其上方）小幅度波动，波动范围应以变形控制标准为依据.Abstract: Based on the semi-contained water model, the permeability of shield-crossing soil and overburden layers when the shield passed through the permeable soil was comprehensively analysed. The analytical solution of the head distribution along the tunnelling direction in the shield-crossing soil layer was derived, and the analytical solution of the two-dimensional seepage field was extended to the corresponding three-dimensional approximate solution. The active and passive failure modes of shallow-buried soil under steady-state seepage were determined using numerical modelling, and a corresponding cylinder-arc-corner-shaped model was established. Subsequently, the formulas of the two-limit support pressures at the tunnel face were obtained by introducing the above-mentioned three-dimensional seepage solution, and the newly calculated results were compared with those of the existing model. The results derived from the developed model were closer to the numerical solution. In addition, disturbance of the seepage field in front of the tunnel face was limited to three times the tunnel diameter and the values of the active and passive limit support pressure increased linearly with increasing head difference. The shield diameter and head difference were found to be the two main factors affecting the active limit pressure. The overburden thickness and shield diameter were the two major factors affecting the passive limit pressure. During tunnelling, the support pressure should be as close as possible to the in-situ transverse earth pressure using the approach that separately calculated the values for soil and water and should slightly fluctuate in the vicinity (preferably above it). The fluctuation range should be determined according to the deformation control standard.
-
Key words:
- Shield tunnelling /
- permeable soil /
- seepage /
- limit support pressure
-
图 1
$y = D$ 处孔隙水压力分布（单位：Mpa）Figure 1. Distribution of pore water pressure at
$y = D$ （unit：Mpa）
图 2
$AB$ 线孔压解析解与数值解对比 （$y = D$ 单位：Mpa）Figure 2. Comparison between analytical solution and numerical solution of pore water pressure on line
$AB$ （$y = D$ unit：Mpa，）
图 3
$MN$ 线孔压解析解与数值解对比（单位：Mpa）Figure 3. Comparison between analytical solution and numerical solution of pore water pressure on line
$MN$ （unit：Mpa）
图 4 模型最大塑性剪切应变率（变形放大50倍）
Figure 4. Maximum plastic shearing strain rate of numerical model （The deformation is magnified 50 times）
图 6 极限支护压力与水头差的关系
Figure 6. Relationship between limit support stress and water head difference
表 1 隧道几何参数及围岩力学参数
Table 1. Geometric parameters of tunnel and mechanics parameters of surrounding soil
D/m C/m H/m c/kPa $\varphi $/（°） $\gamma $/（kg•m–3） ${\gamma _{{\rm{sat}}}}$/（kg•m–3） 5 5 5/10/15 1 30 1 611 1 920 
下载: 导出CSV
表 2 各影响参数取值及主、被动极限支护压力敏感度因子
Table 2. Selection of parameters and its sensitivity to active and passive limit support pressures
参数 取值 参数变化范围/m 敏感度因子 主动 被动 $D$ 10 m 5 m～15 m 0.66 0.94 $C$ 10 m 5 m～15 m 0.08 1.44 $H$ 5 m 0～10 m 0.24 0.19 $\gamma $ 20 kN•m – 3 15 kN•m–3～25 kN•m–3 0.10 0.35 ${\eta _\gamma }$ 0.525 0.4～0.65 0.41 0.17 $\varphi $ 30° 5°～55° 0.05 0.42 ${\eta _\varphi }$ 0.75 0.5～1.0 0.17 0.55 $c$ 5 kPa 0 ～ 10 kPa 0.02 0.05 ${\eta _c}$ 0.75 0.5～ 1.0 0.15 0.06 $\Delta h$ 10 m 0～20 m 0.56 0.23 $q$ 25 kPa 0 ～50 kPa 0.02 0.13
下载: 导出CSV
表 3 地层力学参数
Table 3. Mechanical parameters of soil
土层编号 名称 饱和重度/（kN•m–3） 黏聚力/kPa 内摩擦角/（°） 渗透系数/（cm•s–1） 侧压力系数 （1） 杂填土 19.1 12.32 12.50 3.43 × 10–6 0.65 （2） 粉质黏土 19.3 16.57 18.54 4.63 × 10–6 0.52 （3） 粉质黏土 19.3 15.21 22.35 3.36 × 10–6 0.55 （4） 粘质黏土 19.2 14.64 24.16 3.64 × 10–5 0.55 （5） 粘质黏土 20.0 16.32 18.36 5.73 × 10–4 0.53 （6） 粉质黏土 20.2 15.68 19.83 4.62 × 10–6 0.52
下载: 导出CSV
-
王梦恕. 中国盾构和掘进机隧道技术现状、存在的问题及发展思路[J]. 隧道建设,2014,34(3): 179-187WANG Mengshu. Tunneling by TNM/shield in China:state-of-art,problems and proposals[J]. Tunnel Construction, 2014, 34(3): 179-187 黄正荣,朱伟,梁精华,等. 盾构法隧道开挖面极限支护压力研究[J]. 土木工程学报,2006,39(10): 112-116 doi: 10.3321/j.issn:1000-131X.2006.10.019HUANG Zhengrong, ZHU Wei, LIANG Jing-hua, et al. A study on the limit support pressure at excavation face of shield tunneling[J]. China Civil Engineering Journal, 2006, 39(10): 112-116 doi: 10.3321/j.issn:1000-131X.2006.10.019 Anagnostou G, Kovári K. Face stability conditions with earth-pressure-balanced shields[J]. Tunnelling & Underground Space Technology, 1996, 11(2): 165-173 李鹏飞,张顶立,赵勇. 渗流作用下海底隧道开挖面围岩稳定性分析[J]. 中国公路学报,2013,26(3): 130-136 doi: 10.3969/j.issn.1001-7372.2013.03.015LI Pengfei, ZHANG Dingli, ZHAO Yong. Stability analysis of subsea tunnel face considering seepage[J]. China Journal of Highway and Transport, 2013, 26(3): 130-136 doi: 10.3969/j.issn.1001-7372.2013.03.015 Perazzelli P, Leone T, Anagnostou G. Tunnel face stability under seepage flow conditions[J]. Tunnelling & Underground Space Technology Incorporating Trenchless Technology Research, 2014, 43: 459-469 Lee I M, Nam S W, Ahn J H. Effect of seepage forces on tunnel face stability[J]. Canadian Geotechnical Journal, 2003, 40(2): 342-350 Leca E, Dormieux L. Upper and lower bound solutions for the face stability of shallow circular tunnels in frictional material[J]. Géotechnique, 1990, 40(4): 581-606 doi: 10.1680/geot.1990.40.4.581 王浩然,黄茂松,吕玺琳,等. 考虑渗流影响的盾构隧道开挖面稳定上限分析[J]. 岩土工程学报,2013,35(9): 1696-1704WANG Haoran, HUANG Maosong, LÜ Xilin, et al. Upper-bound limit analysis of stability of shield tunnel face considering seepage[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(9): 1696-1704 孙振宇,张顶立,房倩,等. 浅埋小净距公路隧道围岩压力分布规律[J]. 中国公路学报,2018,31(9): 84-94 doi: 10.3969/j.issn.1001-7372.2018.09.010SUN Zhenyu, ZHANG Dingli, FANG Qian, et al. Distribution of surrounding rock pressure of shallow highway tunnels with small spacing[J]. China Journal of Highway and Transport, 2018, 31(9): 84-94 doi: 10.3969/j.issn.1001-7372.2018.09.010 刘维. 饱和成层土中盾构掘进面稳定理论性研究[D]. 浙江: 浙江大学, 2013LIU Wei. Research on tunnel face stability in saturated layered soil[D]. Zhejiang University, 2013 皇甫明. 暗挖海底隧道围岩稳定性及支护结构受力特征的研究[D]. 北京: 北京交通大学, 2005HUANG Fuming. Research on the surrounding rock-mass and stress characteristics of lining structure for undersea tunnel constructed by excavation method[D]. Beijing Jiaotong University, 2005 王俊杰,郝建云. 土体静止侧压力系数定义及其确定方法综述[J]. 水电能源科学,2013(7): 111-114WANG Junjie, HAO Jianyun. Definition of coefficient of earth pressure and methods review[J]. Water Resources and Power, 2013(7): 111-114 台启民,张顶立,房倩,等. 软弱破碎围岩隧道超前支护确定方法[J]. 岩石力学与工程学报,2016,35(1): 109-118TAI Qiming, ZHANG Dingli, FANG Qian, et al. Determination of advance supports in tunnel construction under unfavourable rock conditions[J]. Chinese Journal of Rock Mechanics and Engineering, 2016, 35(1): 109-118 -
下载:
点击查看大图
计量
- 文章访问数: 484
- HTML全文浏览量: 396
- PDF下载量: 63
- 被引次数: 0