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Wall movement during dewatering inside a diaphragm wall before soil excavation 地下连续墙开挖前降水过程中的墙体运动
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-04-03 DOI: 10.1016/j.undsp.2025.01.003
Chao-Feng Zeng , William Powrie , Chang-Jie Xu , Xiu-Li Xue
Significant movement of in-situ retaining walls is usually assumed to begin with bulk excavation. However, an increasing number of case studies show that lowering the pore water pressures inside a diaphragm wall-type basement enclosure prior to bulk excavation can cause wall movements in the order of some centimeters. This paper describes the results of a laboratory-scale experiment carried out to explore mechanisms of in situ retaining wall movement associated with dewatering inside the enclosure prior to bulk excavation. Dewatering reduces the pore water pressures inside the enclosure more than outside, resulting in the wall moving as an unpropped cantilever supported only by the soil. Lateral effective stresses in the shallow soil behind the wall are reduced, while lateral effective stresses in front of the wall increase. Although the associated lateral movement was small in the laboratory experiment, the movement could be proportionately larger in the field with a less stiff soil and a potentially greater dewatered depth. The implementation of a staged dewatering system, coupled with the potential for phased excavation and propping strategies, can effectively mitigate dewatering-induced wall and soil movements. This approach allows for enhanced stiffness of the wall support system, which can be dynamically adjusted based on real-time displacement monitoring data when necessary.
原位挡土墙的显著移动通常被认为是从大体积开挖开始的。然而,越来越多的实例研究表明,在大规模开挖前降低地下连续墙型围护结构内部孔隙水压力会导致墙体移动数厘米。本文描述了一项实验室规模的实验结果,该实验旨在探索与大体积开挖前围护结构内部脱水相关的原位挡土墙运动机制。脱水使围护结构内部的孔隙水压力比外部更低,导致墙体像无支撑的悬臂一样移动,仅由土壤支撑。墙后浅层土侧有效应力减小,墙前侧有效应力增大。虽然在实验室试验中相关的横向移动很小,但在土壤硬度较低且可能脱水深度较大的现场,这种移动可能成比例地更大。分阶段降水系统的实施,加上分阶段开挖和支护策略的潜力,可以有效地缓解由降水引起的墙和土壤移动。这种方法可以增强墙体支撑系统的刚度,在必要时可以根据实时位移监测数据进行动态调整。
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引用次数: 0
A multi-scale coupled method for nonlinear dynamic response analysis of mountain tunnels subjected to fault movement 断层运动作用下山地隧道非线性动力响应分析的多尺度耦合方法
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-04-02 DOI: 10.1016/j.undsp.2024.09.005
Zhongxian Liu , Jiaqiao Liu , Haitao Yu , Weiguo He
This paper introduces a novel two-step multi-scale coupled method for simulating the nonlinear dynamic behavior of a mountain tunnel subjected to fault movement. In the first step, the broadband seismic responses within a large-scale mountain-fault model can be accurately solved by the indirect boundary element method, converting them into effective input forces around the specified region of interest within the mountain. The second step involves finely simulating the nonlinear dynamic response of the tunnel cross-section in the designated region using the finite element method, with the implementation of a viscoelastic artificial boundary to absorb the reflection of scattered waves at truncated boundaries. Two verification processes are employed to validate the accuracy of the multi-scale coupled method. Furthermore, we illustrate the applicability and efficacy of the new method with an example involving the elastoplastic dynamic analysis of a mountain tunnel under the influence of normal fault movement. The presented example highlights the impact of fault motion parameters, including fault dislocation value and dip angle, on the responses of the mountain tunnel. The results demonstrate that the proposed multi-scale coupled method can achieve full-process seismic simulation, ranging from kilometer-scale fault rupture to centimeter-scale mountain tunnel section damage, with a considerably reduced computational expense.
本文介绍了一种新的两步多尺度耦合方法,用于模拟断层运动作用下山地隧道的非线性动力行为。第一步,采用间接边界元法精确求解大尺度山断层模型内的宽带地震响应,将其转化为山内指定感兴趣区域周围的有效输入力。第二步采用有限元方法精细模拟指定区域内隧道断面的非线性动力响应,采用粘弹性人工边界来吸收截断边界处散射波的反射。采用两个验证过程验证了多尺度耦合方法的准确性。最后,以某山地隧道正断层运动影响下的弹塑性动力分析为例,说明了该方法的适用性和有效性。该算例突出了断层位移值和断层倾角等断层运动参数对山间隧道响应的影响。结果表明,所提出的多尺度耦合方法可以实现从千米尺度断层破裂到厘米尺度山地隧道断面破坏的全过程地震模拟,且计算量大大降低。
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引用次数: 0
Corrosion characteristic of multi-ring shield tunnel containing rubber concrete invert-filling under direct stray current 杂散电流作用下含橡胶混凝土反填多环盾构隧道腐蚀特性研究
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-03-28 DOI: 10.1016/j.undsp.2025.01.002
Shuo Yu , Hao Jin , Liangjie Gu , Peng Gui
Stray current can cause corrosion of underground structural rebar, adding rubber particles to the invert-filling concrete is an effective prevent method to reduce stray current corrosion. In our research, the corrosion calculation model of multi-ring shield tunnel containing rubber concrete invert-filling was established, the coupling analysis of electric field and chemical field in composite structures was realized through mesoscale simulations, and the accuracy of calculation model was verified by full-scale test. Through calculation, the corrosion characteristic of segment rebar and bolt of multi-ring shield tunnel were investigated under different rubber content. The result shows that adding rubber particles to the invert-filling can not only reduce the corrosion current density of segment rebar and tunnel bolt effectively, but also affect the distribution form of rebar corrosion current density in both circumferential and longitudinal directions. When the rubber content increases from 5% to 20%, the maximum corrosion density of segment rebar and tunnel bolt will decrease from 31% to 58% and 30% to 32%, respectively. Under different stray current leakage modes, when the rubber content and input voltage are the same, the segment and bolt corrosion current density under single rail-two points leakage mode is greater than that in the two rails-single point leakage mode.
杂散电流会引起地下结构钢筋的腐蚀,在倒填混凝土中添加橡胶颗粒是减少杂散电流腐蚀的有效预防方法。本研究建立了含橡胶混凝土反填的多环盾构隧道腐蚀计算模型,通过中尺度模拟实现了复合结构中电场和化学场的耦合分析,并通过全尺寸试验验证了计算模型的准确性。通过计算,研究了不同橡胶掺量下多环盾构隧道管片钢筋和锚杆的腐蚀特性。结果表明,在反填料中添加橡胶颗粒不仅能有效降低管片钢筋和隧道螺栓的腐蚀电流密度,而且还能影响钢筋腐蚀电流密度在周向和纵向上的分布形式。当橡胶掺量从5%增加到20%时,管片钢筋和隧道锚杆的最大腐蚀密度分别从31%和30%降低到58%和32%。在不同杂散电流泄漏模式下,当橡胶含量和输入电压相同时,单轨-两点泄漏模式下的管片和螺栓腐蚀电流密度大于二轨-单点泄漏模式下的管片和螺栓腐蚀电流密度。
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引用次数: 0
Shield tunneling efficiency and stability enhancement based on interpretable machine learning and multi-objective optimization 基于可解释机器学习和多目标优化的盾构掘进效率和稳定性提升
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-03-27 DOI: 10.1016/j.undsp.2025.01.001
Wenli Liu , Yang Chen , Tianxiang Liu , Wen Liu , Jue Li , Yangyang Chen
Adequate control of shield machine parameters to ensure the safety and efficiency of shield construction is a difficult and complex problem. To address this problem, this paper proposes a hybrid intelligent optimization framework that combines interpretable machine learning, intelligent optimization algorithms, and multi-objective optimization and decision-making methods. The nonlinear relationship between the input parameters and ground settlement (GS) is fitted based on the light gradient boosting machine (LGBM), and the effect of the input parameters on GS is analysed based on SHapley additive exPlanation for further feature selection. Subsequently, the hyperparameters of LGBM were determined based on the sparrow search algorithm (SSA) to better fit the input–output relationship. On this basis, a multi-objective intelligent optimization model is established to solve the optimized operating parameters of shield machine by non-dominated sorting genetic algorithm II and technique for order preference by similarity to ideal solution to reduce GS and improve drilling efficiency. The results demonstrate that the SSA-LGBM model predicts GS with high accuracy, exhibiting an RMSE of 4.775, a VAF of 0.930 and an R2 of 0.931. These metrics collectively reflect the model’s excellent performance in prediction accuracy, ability to explain data variability, and control of prediction bias. The multi-objective optimization model is effective in optimizing two objectives, and the improvement can reach up to 39.38%; at the same time, the model has high scalability and can also be applied to three or more objectives. The intelligent optimization framework for shield construction parameters proposed in this paper can generate the optimal parameter combinations for shield machine manipulation, and provide reference and guidance when there are conflicting optimization objectives.
对盾构机参数进行充分的控制,以保证盾构施工的安全和效率是一个困难而复杂的问题。为了解决这一问题,本文提出了一种结合可解释机器学习、智能优化算法和多目标优化与决策方法的混合智能优化框架。基于光梯度增强机(LGBM)拟合了输入参数与地面沉降(GS)之间的非线性关系,并基于SHapley加性解释分析了输入参数对GS的影响,进一步进行特征选择。随后,基于麻雀搜索算法(SSA)确定LGBM的超参数,以更好地拟合输入输出关系。在此基础上,采用非主导排序遗传算法II和理想解相似性排序优先技术,建立盾构机多目标智能优化模型,求解盾构机优化后的运行参数,以降低GS,提高钻进效率。结果表明,SSA-LGBM模型预测GS具有较高的精度,RMSE为4.775,VAF为0.930,R2为0.931。这些指标共同反映了模型在预测精度、解释数据变异性的能力和预测偏差控制方面的出色表现。多目标优化模型对两个目标均有效,改进幅度可达39.38%;同时,该模型具有很高的可扩展性,也可以应用于三个或更多的目标。本文提出的盾构施工参数智能优化框架可以生成盾构机操作的最优参数组合,在优化目标冲突时提供参考和指导。
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引用次数: 0
Optimization of reinforced ring base depth for vertical shaft sinking in soft soil using VSM method 基于VSM法的软土地基立井加固环基深度优化
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-03-19 DOI: 10.1016/j.undsp.2024.12.005
Dhyaa A.H. Abualghethe , Baogang Mu , Guoliang Dai , Sijin Liu , Zhongwei Li , Songyu Liu , Lei Han
Constructing vertical shafts in densely populated urban areas with complex geological conditions poses significant challenges, necessitating innovative construction techniques and design optimization. This study investigates the deformation behavior of a 42.5 m deep shaft excavated using the vertical shaft sinking machine (VSM) method in Shanghai’s soft soil conditions comprising deep cohesive soil layers. Comprehensive numerical analysis simulated the VSM construction process, analysing deformations within the shaft structure, surrounding soil, and adjacent buildings while evaluating the influence of varying reinforced ring base depths. Results reveal a significant 30% reduction in the maximum lateral shaft deformation, from 28 to 20 mm, by increasing the reinforced ring base depth to an optimal 16 m, enhancing lateral stability. Vertical deformations exhibited complex settlement and uplift mechanisms in segmental rings and piles, influenced by factors like excavation stages, pile installation, water pressures, and adjacent loads. The optimal 16 m depth effectively mitigated uplift, and optimized load distribution, limiting the maximum settlement to 12 mm while minimizing dewatering-induced uplift effects. Analysis indicated reduced lateral movements and settlements in surrounding buildings with increasing distance from excavation, highlighting VSM’s potential for minimizing impacts on neighboring structures. This study emphasizes VSM’s suitability for shaft projects in geologically complex areas, providing insights for design, mitigating environmental impacts, and enhancing deep excavation safety and efficiency in soft soils. The findings contribute to optimizing vertical shaft construction, ensuring successful underground infrastructure execution in challenging conditions. Identifying the optimal reinforced ring base depth promotes sustainable urban development by minimizing disturbances. This research advances innovative methods and strategies for complex underground projects.
在人口密集、地质条件复杂的城市地区建设竖井,面临着巨大的挑战,需要创新施工技术和优化设计。本文研究了上海软土条件下,采用立井掘进机(VSM)法开挖的42.5 m深竖井的变形特性。综合数值分析模拟了VSM施工过程,分析了竖井结构内部、周围土体和邻近建筑物的变形情况,同时评价了不同加筋环底深度对施工的影响。结果显示,通过将加固环底部深度增加到最佳的16米,增强横向稳定性,最大横向轴变形显著减少30%,从28毫米减少到20毫米。受开挖阶段、桩身安装、水压和邻近荷载等因素的影响,环段和桩段的竖向变形表现出复杂的沉降和隆升机制。最佳深度为16 m,有效地缓解了隆升,优化了荷载分布,将最大沉降限制在12 mm,同时最大限度地减少了脱水引起的隆升效应。分析表明,随着挖掘距离的增加,周围建筑物的横向移动和沉降减少,突出了VSM对邻近建筑物影响最小化的潜力。本研究强调了VSM在地质复杂地区竖井工程中的适用性,为设计、减轻环境影响以及提高软土中深挖的安全性和效率提供了见解。研究结果有助于优化竖井施工,确保在具有挑战性的条件下成功实施地下基础设施。确定最佳加固环基底深度,通过减少干扰促进城市可持续发展。本研究为复杂地下工程提供了创新的方法和策略。
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引用次数: 0
Cutting-edge approaches to specific energy prediction in TBM disc cutters: Integrating COSSA-RF model with three interpretative techniques TBM盘式铣刀比能预测的前沿方法:将COSSA-RF模型与三种解释技术相结合
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-03-10 DOI: 10.1016/j.undsp.2024.11.004
Jian Zhou , Zijian Liu , Chuanqi Li , Kun Du , Haiqing Yang
Specific energy (SE) is an important index to measure crushing efficiency in mechanized tunnel excavation. Accurate prediction of the SE of tunnel boring machine disc cutters is important for optimizing the crushing process, reducing energy consumption, and minimizing machine wear. Therefore, in this paper, the sparrow search algorithm (SSA), combined with six chaotic mapping strategies, is utilized to optimize the random forest (RF) model for predicting SE, referred to as the COSSA-RF prediction models. For this purpose, an SE prediction database was established for training and validating model performance, encompassing 160 sets of experimental data, each with six input parameters: uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), disc cutter diameter (D), cutter tip width (T), cutter spacing (S), and cutter penetration depth (P), along with a target parameter, SE. The evaluation results indicate that the COSSA-RF models demonstrate superior performance compared to other four machine learning models. In particular, the Chebyshev map-SSA-RF (CHSSA-RF) model achieves the most satisfactory prediction accuracy among all models, resulting in the highest coefficient of determination R2 and dynamic variance-weighted global performance indicator values (0.9756 and 0.0814) and the lowest values of root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) (6.4742, 4.0003, and 20.41%). Lastly, the results of interpretability analysis of the best model through SHapley Additive exPlanations, local interpretable model-agnostic explanations, and Vivid methods show that the importance of input parameters ranked as follows: UCS, BTS, P, S, T, and D. Moreover, interactions between parameters (UCS and BTS, BTS and P, and BTS and S) significantly influence the model predictions.
比能(SE)是衡量机械化隧道开挖破碎效率的重要指标。准确预测隧道掘进机盘式铣刀的切削效率对优化破碎工艺、降低能耗、减少机器磨损具有重要意义。因此,本文利用麻雀搜索算法(SSA),结合6种混沌映射策略,对预测SE的随机森林(RF)模型进行优化,简称COSSA-RF预测模型。为此,我们建立了一个SE预测数据库,用于训练和验证模型的性能,该数据库包含160组实验数据,每组数据有6个输入参数:单轴抗压强度(UCS)、巴西抗拉强度(BTS)、盘式刀具直径(D)、刀具尖端宽度(T)、刀具间距(S)和刀具穿透深度(P),以及目标参数SE。评估结果表明,与其他四种机器学习模型相比,COSSA-RF模型表现出优越的性能。其中,Chebyshev map-SSA-RF (CHSSA-RF)模型的预测精度在所有模型中最令人满意,其决定系数R2和动态方差加权全局性能指标值最高(0.9756和0.0814),均方根误差(RMSE)、平均绝对误差(MAE)和平均绝对百分比误差(MAPE)最低(6.4742、4.0003和20.41%)。最后,通过SHapley加性解释、局部可解释模型不可知解释和Vivid方法对最佳模型的可解释性分析结果表明,输入参数的重要性依次为:UCS、BTS、P、S、T和d,参数之间的交互作用(UCS与BTS、BTS与P、BTS与S)显著影响模型预测。
{"title":"Cutting-edge approaches to specific energy prediction in TBM disc cutters: Integrating COSSA-RF model with three interpretative techniques","authors":"Jian Zhou ,&nbsp;Zijian Liu ,&nbsp;Chuanqi Li ,&nbsp;Kun Du ,&nbsp;Haiqing Yang","doi":"10.1016/j.undsp.2024.11.004","DOIUrl":"10.1016/j.undsp.2024.11.004","url":null,"abstract":"<div><div>Specific energy (SE) is an important index to measure crushing efficiency in mechanized tunnel excavation. Accurate prediction of the SE of tunnel boring machine disc cutters is important for optimizing the crushing process, reducing energy consumption, and minimizing machine wear. Therefore, in this paper, the sparrow search algorithm (SSA), combined with six chaotic mapping strategies, is utilized to optimize the random forest (RF) model for predicting SE, referred to as the COSSA-RF prediction models. For this purpose, an SE prediction database was established for training and validating model performance, encompassing 160 sets of experimental data, each with six input parameters: uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), disc cutter diameter (<em>D</em>), cutter tip width (<em>T</em>), cutter spacing (<em>S</em>), and cutter penetration depth (<em>P</em>), along with a target parameter, SE. The evaluation results indicate that the COSSA-RF models demonstrate superior performance compared to other four machine learning models. In particular, the Chebyshev map-SSA-RF (CHSSA-RF) model achieves the most satisfactory prediction accuracy among all models, resulting in the highest coefficient of determination <em>R</em><sup>2</sup> and dynamic variance-weighted global performance indicator values (0.9756 and 0.0814) and the lowest values of root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) (6.4742, 4.0003, and 20.41%). Lastly, the results of interpretability analysis of the best model through SHapley Additive exPlanations, local interpretable model-agnostic explanations, and Vivid methods show that the importance of input parameters ranked as follows: UCS, BTS, <em>P</em>, <em>S</em>, <em>T</em>, and <em>D</em>. Moreover, interactions between parameters (UCS and BTS, BTS and <em>P</em>, and BTS and <em>S</em>) significantly influence the model predictions.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"22 ","pages":"Pages 241-262"},"PeriodicalIF":8.2,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Tunneling beneath the pile-raft foundations of high-speed railways: Progressive arching deformation and pile settlement behavior 高速铁路桩筏基础下隧道开挖:渐进式拱变形与桩沉降行为
IF 8.3 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-03-04 DOI: 10.1016/j.undsp.2024.12.004
Botao Hu , Yao Shan , Yu Zhao , Binglong Wang , Shunhua Zhou , Giovanni S. Alberti , Wenjie Ma , Bettina Detmann , Laurent Briançon
Due to the unclear mechanisms behind tunneling-induced deformation of pile-raft foundations, there are strict global restrictions on tunneling beneath embankments of high-speed railways. This study conducted a series of two-dimensional tunneling model tests to investigate the tunneling-induced deformation characteristics and mechanisms of pile-raft foundations. Soil displacement field and pile settlement were measured using particle image velocimetry and displacement transducers. The changes in soil displacement and the flexure of the pile-raft foundation in response to varying tunnel-pile distances, ground surface loads, and tunnel volume loss were analyzed. The results indicate that the tunneling-disturbed zone can be categorized into a loosened zone and an arch zone as identified by the propagation and separation of shear bands, with significant soil settlement occurring in the loosened zone. The maximum settlement of piles in a pile-raft foundation is greater than that in greenfield due to the larger loosened zone. However, the settlement width at the ground surface in pile-raft foundations is reduced due to the blocking effect of the piles. According to the relative position between the piles and the formed arch structure, three patterns of tunneling-ground-pile systems can be identified. As the tunnel-pile distance increases, the maximum settlement of the piles decreases. Increasing surface loads hardly affects the maximum settlement value of the pile, while the tunneling-induced arch zone expands significantly. This study provides a fundamental understanding of pile settlement behavior for tunneling beneath the pile-raft foundations of high-speed railways.
由于隧道引起桩筏基础变形的机制尚不清楚,全球对高速铁路路堤下隧道施工有严格的限制。通过一系列二维隧道模型试验,研究桩筏基础的隧道致变形特征及机理。采用颗粒图像测速仪和位移传感器测量了土体位移场和桩沉降。分析了土体位移和桩筏基础挠曲随隧道桩距、地表荷载和隧道体积损失的变化规律。结果表明:以剪切带的扩展和分离为特征,隧道扰动区可分为松散区和拱区,松散区土体沉降明显;桩筏基础由于松动区较大,桩的最大沉降量大于绿地基础。而桩筏基础由于桩的阻塞作用,使地基表面沉降宽度减小。根据桩与已成形的拱结构之间的相对位置,可以识别出三种隧道-地基-桩体系模式。随着隧道桩距的增大,桩的最大沉降减小。增加表面荷载对桩的最大沉降值影响不大,而隧道拱区扩展明显。本研究为高速铁路桩筏基础下隧道的桩沉降行为提供了基础认识。
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引用次数: 0
Field monitoring and instrumentation in microtunnelling/pipe jacking: A review and future directions 微隧道/顶管的现场监测与仪器:综述与未来发展方向
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-02-25 DOI: 10.1016/j.undsp.2024.12.003
Asad Wadood , Bryan A. McCabe , Brian B. Sheil
The popularity of trenchless techniques as a means of utility pipeline installation in urban environments, specifically microtunnelling/pipe-jacking, has increased in recent years due to its minimally-disruptive nature and reduced carbon footprint in comparison to conventional open-cut excavation methods. The response of pipes during the jacking process is complex and is governed by several factors, including ground conditions, the amount and distribution of lubrication, pipe and annulus size, pipeline misalignments and jacking force eccentricity, among others. Design practice remains based on empirical equations and previous drives through similar geology, resulting in uncertainty in jacking force estimates, thereby restricting adoption of the technique. In order to improve our understanding of the pipe-jacking process, pipes incorporating sensors providing real-time measurements of earth pressures, pore water pressures, axial strains and hoop strains can be used; but the number of such studies reported in the literature is small and the potential of instrumentation on routine projects is largely untapped. Moreover, jacking pipe monitoring practice lags behind the state-of-the-art instrumentation techniques used for monitoring other geotechnical infrastructure. The purpose of this paper is to provide a thorough review of learnings from instrumented pipe-jacking case studies and other supporting research, as well as to propose potential solutions to research gaps in the current state of design practice and field monitoring of pipe jacking projects.
非开挖技术作为城市环境中公用管道安装的一种手段,特别是微隧道/顶管,近年来越来越受欢迎,因为与传统的露天开挖方法相比,它具有最小的破坏性和更少的碳足迹。顶进过程中管道的响应是复杂的,受多种因素的影响,包括地面条件、润滑量和分布、管道和环空尺寸、管道错位和顶进力偏心等。设计实践仍然基于经验方程和以前在类似地质条件下的驱动,导致顶升力估计的不确定性,从而限制了该技术的采用。为了提高我们对顶管过程的理解,可以使用带有传感器的管道,这些传感器可以实时测量土压力、孔隙水压力、轴向应变和环向应变;但在文献中报道的此类研究数量很少,仪器在常规项目中的潜力在很大程度上尚未开发。此外,顶管监测实践落后于用于监测其他岩土基础设施的最先进的仪器技术。本文的目的是全面回顾从仪器顶管案例研究和其他支持性研究中获得的经验教训,并提出潜在的解决方案,以弥补目前设计实践和顶管项目现场监测中的研究空白。
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引用次数: 0
Test and field application of fracture evolution of large-span tunnel under NPR bolt compensation support system NPR 螺栓补偿支撑系统下大跨度隧道断裂演化试验与现场应用
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-02-15 DOI: 10.1016/j.undsp.2024.12.002
Jun Yang , Kexue Wang , Wenhui Bian , Yanbo Zhang , Xiaohui He , Yi Fang , Zhicheng Sun
Shallow-buried large-span tunnels may bend or collapse owing to loads, and their surface structures present considerable safety issues. At Huashanyilu station on Qingdao Metro Line 6 in China, theoretical studies and interior model tests were conducted to effectively increase the bearing capacity of the tunnel. The anchoring bearing mechanism of the high prestress compensating support system was revealed, and the system was built using a negative Poisson’s ratio (NPR) bolt at its core. We compared and analyzed the fracture evolution characteristics of the compensating and conventional support systems under various loads. The results showed that the compensating support system effectively increased the support strength and residual safety factor of the bearing arch, whereas the use of a high-prestress NPR anchor reduced the early deformation of the surrounding rock. The coupling failure modes of the arch tension extrusion failure and arch foot shear fracture occurred when the tunnel surrounding the rock was overloaded. The compensatory support system produces a bearing arch that is extremely resistant to external loads with minimal deformation of the tunnel surface and arch frame, excellent surrounding rock integrity, and a low stress rate. The radial and tangential peak stresses exceeded those of the passive support system, and the structural block fell when it became unstable. The maximum displacement of the arch stays constant at −5.7 mm after tunnel excavation. NPR bolts have remarkable applications in this field. The conclusions of this study have a significant impact on the regulation of the stability of the surrounding rock in large-span tunnels.
浅埋大跨度隧道在荷载作用下可能发生弯曲或坍塌,其表面结构存在较大的安全问题。在中国青岛地铁6号线华山驿路站进行了理论研究和室内模型试验,以有效提高隧道的承载能力。揭示了高预应力补偿支护体系的锚固承载机理,并采用负泊松比锚杆构建了高预应力补偿支护体系。对比分析了补偿支护系统和常规支护系统在不同载荷作用下的断裂演化特征。结果表明:补偿支护系统有效提高了承载拱的支护强度和残余安全系数,而采用高预应力NPR锚杆则降低了围岩的早期变形;巷道围岩超载时,拱张挤破坏与拱脚剪切破坏的耦合破坏模式。补偿支撑系统产生的承重拱具有极强的抗外部载荷能力,隧道表面和拱架变形最小,围岩完整性好,应力率低。径向和切向峰值应力均超过被动支护体系峰值应力,结构块体失稳时发生垮塌。隧道开挖后拱的最大位移保持不变,为- 5.7 mm。NPR螺栓在这一领域有着显著的应用。研究结论对大跨度隧道围岩稳定性的调控具有重要意义。
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引用次数: 0
Overall smoke control performance using naturally ventilated shafts in tunnel fires with multiple fire sources 自然通风竖井在多火源隧道火灾中的整体防烟性能
IF 8.2 1区 工程技术 Q1 ENGINEERING, CIVIL Pub Date : 2025-02-13 DOI: 10.1016/j.undsp.2024.10.005
Kun He , Ying Zhen Li , Haukur Ingason , Xudong Cheng
This study investigates the overall smoke control performance using shafts in a naturally ventilated tunnel in the case of multiple fire sources. Detailed comparisons were also made with the corresponding single fire source scenarios. The results show that the interaction between multiple fire sources affects smoke control performance, resulting in a lower smoke layer height compared to the corresponding single fire scenario. For the multiple fire sources scenarios, the smoke layer height in the fire section first decreases and then keeps stable, as the fire center spacing increases. The smoke layer height in the fire section is 20%–25% lower than that in a single fire source scenario for a given total heat release rate. The minimum smoke layer height at the adjacent non-fire tunnel section is much lower than that in the fire section due to the disturbance of the first group of shafts. For a small tunnel fire such as a car fire, the critical safety distances for firefighters and evacuees increase as the fire source spacing decreases. For a large tunnel fire such as a bus fire, the effect of fire source spacing on the critical safety distance is limited, while the shaft interval plays an important role. The fire source spacing and the number of fire sources have limited influences on the smoke spread length due to the small differences in the induced air flow velocity and overall smoke exhaust rate through shafts. When the fire sources are located under one shaft, the number of shafts required for complete smoke exhaust is the least and the total smoke spread length is the shortest. For a given fire location, the smoke spread length increases significantly with an increasing shaft interval. This study contributes to the design of natural ventilation shafts in tunnels possibly with multiple fire sources.
本文研究了多火源情况下自然通风隧道中竖井的整体防烟性能。并与相应的单一火源情景进行了详细比较。结果表明,多个火源之间的相互作用影响了烟雾控制性能,导致烟雾层高度低于相应的单一火灾场景。对于多火源场景,随着火源中心间距的增大,火灾段烟层高度先降低后保持稳定。在总放热率相同的情况下,火灾段的烟层高度比单火源场景低20% ~ 25%。由于第一组竖井的扰动,相邻非火灾隧道段的最小烟层高度远低于火灾隧道段的最小烟层高度。对于小型隧道火灾,如汽车火灾,消防员和疏散人员的临界安全距离随着火源间距的减小而增大。对于客车火灾等大型隧道火灾,火源间距对临界安全距离的影响有限,而竖井间距则起着重要作用。火源间距和火源数量对烟蔓延长度的影响有限,因为诱导气流速度和通过竖井的总排烟率差异较小。当火源位于一个竖井以下时,完全排烟所需的竖井数最少,总烟蔓延长度最短。对于给定的火灾地点,随着竖井间距的增加,烟雾扩散长度显著增加。本研究为可能存在多火源的隧道自然通风井的设计提供了理论依据。
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Underground Space
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