Mechanics and deformation characteristics of bored pile and rotary jet grouting pile composite structure for tunnel in water-rich stratum
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摘要: 为探讨“钻孔灌注桩+旋喷桩”组合型结构在PBA隧道施工中的适用性,揭示其力学效应,依托北京轨道交通13号线东三路站—天通苑东站暗挖区间工程实例,针对承压富水地层中“钻孔桩+旋喷桩”组合型结构围护下的PBA隧道施工全过程进行了数值仿真,分析了关键施工步序下该组合型结构的内力、变形情况以及其施工过程对地表沉降和地层塑性区的影响,探讨了桩径、桩身插入比和桩间咬合量对其力学表现的影响。结果表明:(1)施作“钻孔桩+旋喷桩”组合型结构阶段对地表沉降槽和地层塑性区的影响不大;(2)“钻孔桩+旋喷桩”组合型结构在暗挖隧道施工中主要出现朝向隧道内侧的水平侧移,整体侧移量沿深度方向呈二次曲线形态,最大侧移出现在旋喷桩中部及钻孔灌注桩上部,底板以下侧移较小;(3)主洞开挖之后,钻孔灌注桩及旋喷桩的轴力较均匀地分布在整个主洞开挖临空段,轴力和弯矩值在底板以下急剧缩减,最大轴力及弯矩均位于底板附近。
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关键词:
- “钻孔桩+旋喷桩”组合型结构 /
- 隧道暗挖施工 /
- 力学响应 /
- 流固耦合效应
Abstract: To explore the applicability of the "bored pile+jet grouting pile" composite structure in the construction of PBA tunnel and reveal its mechanical effect, based on the engineering example of the underground excavation section of Dongsanlu Station to Tiantongyuan East Station of Beijing Rail Transit Line 13, the numerical simulation of the whole construction process of PBA tunnel under the support of the composite structure in confined water rich strata was carried out. The internal force and deformation of the composite structure under the key construction steps and the influence of its construction process on the surface settlement and formation of the plastic zone were analyzed, and the effects of pile diameter, pile insertion ratio, and pile interlocking on its mechanical performance were discussed. The results show that: (1) The construction stage of the composite structure has little effect on the surface settlement trough and formation plastic zone; (2) The composite structure mainly appears horizontal lateral displacement towards the inner side of the tunnel during the construction of the tunnel. The overall lateral displacement is in the form of a quadratic curve along the depth direction. The maximum lateral displacement occurs in the middle of the jet grouting pile and the upper part of the bored pile, and the lateral displacement below the bottom plate is small; (3) After the excavation of the main tunnel, the axial forces of bored piles and jet grouting piles are evenly distributed in the free section of the excavation of the main tunnel, the axial forces and bending moments are sharply reduced below the bottom plate, and the maximum axial forces and bending moments are located near the bottom plate. -
表 1 岩土物理力学参数表
土层编号 土层名称 天然容重
γ/(kN·m−3)泊松比 黏聚力
c/kPa内摩擦角
φ/(°)压缩模量
Es/MPa① 杂填土 18.0 0.35 5 10 12.5 ③ 细砂 20.0 0.22 0 32 41.5 ④ 粉质黏土 20.5 0.30 23 15 30.0 ⑤3 中砂 20.5 0.22 0 36 50.0 ⑤4 圆砾 21.0 0.20 0 34 55.0 ⑦ 粉质黏土 20.2 0.27 30 16 39.3 表 2 支护结构物理力学参数表[6]
结构名称 单元类型 弹性模量E/GPa 重度γ/(kN·m−3) 泊松比 初支 2D板单元 28.0 24.5 0.22 二衬 实体单元 31.5 25.0 0.25 冠梁 实体单元 31.5 25.0 0.25 旋喷桩 1D梁单元 19.0 21.5 0.20 钻孔灌注桩 1D梁单元 31.5 25.0 0.25 表 3 数值模拟施工步序
施工步序 步序详情 FS 初始渗流场分析,激活土体及初始水位 IS 初始应力场分析,位移清零 CS1 管棚注浆,开挖前导洞超前注浆 CS2-CS25 导洞开挖支护,同步超前注浆 CS26 导洞开挖完成 CS27 “钻孔桩+旋喷桩”围护结构施作 CS28 冠梁及拱脚初支施作 CS29 导洞墙背回填 CS30 围护结构及冠梁施作完成,回填完成 CS31-CS62 分步激活渗流面水头边界进行稳态分析,
同时进行主洞开挖支护CS63 主洞开挖支护完成 CS64-CS67 分段拆除临时支护,施作二衬结构 CS68 主洞二衬完成 表 4 极差分析结果
目标参量 桩身最大侧移/mm 桩身最大轴力/kN 桩身最大弯矩/(kN·m) 影响因素 A B C A B C A B C $ \stackrel{-}{{\mathit{K}}_{1}} $ 10.88 10.28 10.10 640.16 668.05 679.71 75.35 86.69 80.50 $ \stackrel{-}{{\mathit{K}}_{2}} $ 10.42 10.09 10.11 671.46 676.17 676.73 90.11 88.97 83.42 $ \stackrel{-}{{\mathit{K}}_{3}} $ 9.55 9.88 9.94 685.46 680.04 678.97 88.22 89.75 88.92 $ \stackrel{-}{{\mathit{K}}_{4}} $ 9.09 9.70 9.81 726.46 699.25 688.12 97.00 85.29 97.86 极差R 1.79 0.58 0.30 86.30 31.20 11.39 21.65 4.46 17.36 注:影响因素A,B,C分别为桩径、桩身插入比、桩间咬合量。 -
[1] LI Z G, SUI Z L, ZHANG Q Z, et al. Supporting design and stability analysis of a subway station's main body tunneling[J]. Applied Mechanics and Materials, 2013, 470: 970-975. doi: 10.4028/www.scientific.net/AMM.470.970 [2] LIU X R, LIU Y Q, QU W B, et al. Internal force calculation and supporting parameters sensitivity analysis of side piles in the subway station excavated by Pile-Beam-Arch method[J]. Tunnelling and Underground Space Technology, 2016, 56: 186-201. doi: 10.1016/j.tust.2016.03.012 [3] 武钰斌. PBA工法地铁车站钻孔咬合桩围护结构止水效果及开挖变形研究[D]. 北京: 北京交通大学, 2020. (WU Y B. Research on waterproof effect and excavation deformation of retaining structure of secant piles in PBA method constructed subway station[D]. Beijing: Beijing Jiaotong University, 2020. (in Chinese)WU Y B. Research on waterproof effect and excavation deformation of retaining structure of secant piles in PBA method constructed subway station[D]. Beijing: Beijing Jiaotong University, 2020. (in Chinese) [4] 朱雅倩, 薛洪松, 刘希胜, 等. 暗挖车站地下连续墙施工地表沉降分析[J]. 岩土工程技术, 2021, 35(2): 77-83,98. (ZHU Y Q, XUE H S, LIU X S, et al. Analysis on the ground settlement in the construction of diaphragm wall of subway excavated stations[J]. Geotechnical Engineering Technique, 2021, 35(2): 77-83,98. (in Chinese) doi: 10.3969/j.issn.1007-2993.2021.02.002ZHU Y Q, XUE H S, LIU X S, et al. Analysis on the ground settlement in the construction of diaphragm wall of subway excavated stations[J]. Geotechnical Engineering Technique, 2021, 35(2): 77-83,98. (in Chinese) doi: 10.3969/j.issn.1007-2993.2021.02.002 [5] 薛洪松, 朱雅倩, 张志红, 等. 暗挖车站洞内地下连续墙施工地层效应分析[J]. 科学技术与工程, 2022, 22(7): 2878-2886. (XUE H S, ZHU Y Q, ZHANG Z H, et al. Stratum effect of diaphragm wall construction with pile-beam-arch method[J]. Science Technology and Engineering, 2022, 22(7): 2878-2886. (in Chinese) doi: 10.3969/j.issn.1671-1815.2022.07.043XUE H S, ZHU Y Q, ZHANG Z H, et al. Stratum effect of diaphragm wall construction with pile-beam-arch method[J]. Science Technology and Engineering, 2022, 22(7): 2878-2886. (in Chinese) doi: 10.3969/j.issn.1671-1815.2022.07.043 [6] 王 扩, 姚爱军, 张 东, 等. 富水地层中暗挖地铁车站洞内咬合桩力学性能及优化[J]. 地下空间与工程学报, 2021, 17(S2): 779-787. (WANG K, YAO A J, ZHANG D, et al. Mechanical properties and optimization of secant piles in underground excavated subway stations in water-rich stratum[J]. Chinese Journal of Underground Space and Engineering, 2021, 17(S2): 779-787. (in Chinese)WANG K, YAO A J, ZHANG D, et al. Mechanical properties and optimization of secant piles in underground excavated subway stations in water-rich stratum[J]. Chinese Journal of Underground Space and Engineering, 2021, 17(S2): 779-787. (in Chinese) [7] 叶 小. 基于流固耦合的双碑隧道富水区围岩稳定性研究[D]. 重庆: 重庆交通大学, 2019. (YE X. Study on stability of surrounding rock in water-rich area of Shuangbei tunnel based on fluid-solid coupling[D]. Chongqing: Chongqing Jiaotong University, 2019. (in Chinese)YE X. Study on stability of surrounding rock in water-rich area of Shuangbei tunnel based on fluid-solid coupling[D]. Chongqing: Chongqing Jiaotong University, 2019. (in Chinese) [8] 袁羊扣, 焦有权, 罗沐池, 等. 洞桩法边桩变形的荷载-结构模型[J]. 兰州理工大学学报, 2020, 46(1): 123-128. (YUAN Y K, JIAO Y Q, LUO M C, et al. Load-structure model of side pile deformation based on pile-tunnel method[J]. Journal of Lanzhou University of Technology, 2020, 46(1): 123-128. (in Chinese) doi: 10.3969/j.issn.1673-5196.2020.01.021YUAN Y K, JIAO Y Q, LUO M C, et al. Load-structure model of side pile deformation based on pile-tunnel method[J]. Journal of Lanzhou University of Technology, 2020, 46(1): 123-128. (in Chinese) doi: 10.3969/j.issn.1673-5196.2020.01.021 [9] 杜昌隆, 朱雅倩, 马 路, 等. PBA暗挖地铁车站洞内地下连续墙施工力学响应分析[J]. 岩土工程技术, 2023, 37(2): 135-141. (DU C L, ZHU Y Q, MA L, et al. Mechanical response analysis on construction of diaphragm wall in PBA underground excavation subway station[J]. Geotechnical Engineering Technique, 2023, 37(2): 135-141. (in Chinese)DU C L, ZHU Y Q, MA L, et al. Mechanical response analysis on construction of diaphragm wall in PBA underground excavation subway station[J]. Geotechnical Engineering Technique, 2023, 37(2): 135-141. (in Chinese) [10] 秦晓英. 城市地铁车站PBA工法施工力学效应的数值模拟研究[D]. 重庆: 重庆大学, 2008. (QIN X Y. Study on numerical simulation of mechanical effect of PBA method for city subway station with shallow buried[D]. Chongqing: Chongqing University, 2008. (in Chinese)QIN X Y. Study on numerical simulation of mechanical effect of PBA method for city subway station with shallow buried[D]. Chongqing: Chongqing University, 2008. (in Chinese) [11] 姚宣德, 王梦恕. 地铁浅埋暗挖法施工引起的地表沉降控制标准的统计分析[J]. 岩石力学与工程学报, 2006, 25(10): 2030-2035. (YAO X D, WANG M S. Statistic analysis of guideposts for ground settlement induced by shallow tunnel construction[J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25(10): 2030-2035. (in Chinese) doi: 10.3321/j.issn:1000-6915.2006.10.013YAO X D, WANG M S. Statistic analysis of guideposts for ground settlement induced by shallow tunnel construction[J]. Chinese Journal of Rock Mechanics and Engineering, 2006, 25(10): 2030-2035. (in Chinese) doi: 10.3321/j.issn:1000-6915.2006.10.013 [12] WANG Q K, HU Z B, JI Y K, et al. Centrifugal model test based bearing characteristics and analytical model of uplift pile in combined composite ground[J]. Rock Mechanics and Rock Engineering, 2022, 55(6): 3525-3543. doi: 10.1007/s00603-022-02820-z -