深圳大学学报理工版

郑镇跡,曹利强,苏栋,等.隔离桩对隧道开挖引起沉降的控制效能分析[J].深圳大学学报理工版,2022,39(6):615-621.[doi:10.3724/SP.J.1249.2022.06615]
ZHENG Zhenji,CAO Liqiang,SU Dong,et al.Efficiency investigation of mitigation effect of isolation piles on tunneling-induced ground settlements[J].Journal of Shenzhen University Science and Engineering,2022,39(6):615-621.[doi:10.3724/SP.J.1249.2022.06615]

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隔离桩对隧道开挖引起沉降的控制效能分析

郑镇跡¹，曹利强^1,2,3，苏栋^1,2,3，陈湘生^1,2,3

1.深圳大学土木与交通工程学院，广东深圳518060;2.深圳大学滨海城市韧性基础设施教育部重点实验室，广东深圳518060;3.深圳市地铁地下车站绿色高效智能建造重点实验室，广东深圳518060

关键词：岩土工程;隧道开挖;隔离桩;地层沉降;变形控制;数值仿真

Efficiency investigation of mitigation effect of isolation piles on tunneling-induced ground settlements

ZHENG Zhenji¹，CAO Liqiang^1,2,3，SU Dong^1,2,3，and CHEN Xiangsheng^1,2,3

1.College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, Guangdong Province, P. R. China;2.Key Laboratory for Resilient Infrastructures of Coastal Cities (MOE), Shenzhen University, Shenzhen 518060, Guangdong Province, P. R. China;3.Shenzhen Key Laboratory of Green, Efficient and Intelligent Construction of Underground Metro Station, Shenzhen 518060, Guangdong Province, P. R. China

Keywords：geotechnical engineering; tunnel excavation; isolation pile; ground settlements; deformation control;numerical simulation

DOI: 10.3724/SP.J.1249.2022.06615

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为研究隔离桩对地表及深层土体沉降的控制效能，对Plaxis2d中模拟隔离桩的实现方法进行分析，建立“隧道-隔离桩”相互作用有限元模型，研究桩长、桩径、桩顶埋深、桩水平位置以及隧道埋深等参数对控制效能的影响．结果表明，隔离桩对地表及地层深层土体沉降的控制效能不同，在设置隧道均匀径向收缩模式下，对地表而言桩长的影响最为明显，实际工程中应深入隧道底部，至少达到隧道半径，以保证对地表沉降的控制效果；隔离桩设置得离隧道越近，控制效能越好，尤其是对深层土体沉降的控制；桩直径在0.6～1.4m内变化对隔离桩沉降控制效能影响不明显；埋入式隔离桩对地表沉降的控制效能与非埋入式相比差别不大，但对地层深层土体的沉降控制效能明显优于非埋入式；对于相同的隔离桩，隧道埋深越深，隔离桩对地表沉降的控制效能越低．隔离桩对一定范围的深层土体沉降控制效率基本为负值，说明隔离桩的设置反而加大了深层土体原有沉降，出现负面效果．研究结果可为隔离桩的设计施工提供参考.

In order to study the control efficiency of isolation pile on the settlement of the surface and deep soil, we analyze the implementation method of simulated isolation pile in Plaxis2d, and establish the finite element model of the tunnel and isolation pile interaction to study the effects of the pile length, pile diameter, buried depth of pile top, pile horizontal position and tunnel buried depth on the control effectiveness. The results show that the control effectiveness of the isolation pile on the ground surface and deep soil strata subsidence is different. Under the uniform radial contraction mode of the tunnel, the pile length has the most obvious impact on the ground surface. In practical projects, it should be at least one radiu at the bottom of the deep tunnel to ensure the control effect on surface subsidence. The closer the isolation pile is set to the tunnel, the better the control efficiency is, especially to the settlement of deep soil. Within 0. 6~1. 4 m pile diameter changes on the isolation is of little influence on the pile settlement control effectiveness. The control efficiency of buried isolation pile on ground settlement is not much different from that of non-buried one, but the control efficiency of deep soil settlement in the ground is obviously better than that of the non-buried isolation pile. For the same isolation pile, the deeper the tunnel is buried, the lower the control efficiency of the isolation pile on surface settlement. In this study, the control efficiency of isolation piles on the settlement of deep soil mass is basically negative, indicating that the placement of isolation piles increases the original settlement of deep soil mass, instead, resulting in negative effects. The research can provide a reference for the design and construction of isolation pile.

引言
1 隔离桩二维数值模拟方法分析与验证
2 隔离桩变形控制效率因素分析
3 结语

图1 隔离桩数值模拟验证模型Fig. 1 Isolation pile simulation verification mode.

表1 土体主要参数Table 1 Main soil parameters of soil mass

图2 既有桥桩桩身水平位移曲线Fig. 2 Pile horizontal displacement curve of existing bridge piles without isolation piles in Ref. [9] (solid black line) and this paper (dotted red line) as well as with isolation piles in Ref. [9] (bule solid line) and this paper (double dotted perpul line)

图3 不同模拟工况下的地层沉降云图（a）原隧道；（b）方法1；（c）方法2；（d）方法3 Fig. 3 Vertical settlement cloud maps of stratum under (a) original tunnel, (b) method 1, (c) method 2, and (d) method 3.

图4 不同模拟工况下的地表沉降Fig. 4 Surface settlement under different simulation conditions.

表2 研究因素及水平表1） Table 2 Factors and horizontal tablem

图5 桩长变化对地表沉降的影响Fig. 5 Influence of length of isolation pile on surface settlement.

图6 桩长变化对控制效率的影响Fig. 6 Impact of pile length on control efficiency.

图7 水平距离变化对地表沉降的影响Fig. 7 Influence of horizontal distance between isolation pile and tunnel on surface settlement.

图8 水平距离变化对控制效率的影响Fig. 8 Impact of horizontal distance between isolation pile and tunnel on control efficiency.

图9 桩径变化对地表沉降的影响Fig. 9 Influence of diameter of isolation pile on surface settlement.

图10 桩顶埋深变化对地表沉降的影响Fig. 10 Influence of pile top buried depth on surface settlemet.

图11 桩顶埋深变化对控制效率的影响Fig. 11 Impact of the depth of the top of the pileon the control efficiency.

图12 竖向位移随深度变化曲线（X=15 m为参考平面） Fig. 12 Vertical displacement versus depth for different tunnel depth (using X=15 m as reference surface).

图13 地表沉降值随隧道埋深变化曲线Fig. 13 Surface settlement versus tunnel depth.

图14 深层土体沉降值随隧道埋深变化曲线Fig. 14 Isolation pile and deep soil settlement as function of tunnel depth.

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