Underground Space最新文献

Series of centrifuge shaking table tests study on seismic response of subway station structures in soft soil sites 软土场地地铁站结构地震响应的离心振动台系列试验研究

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-28 DOI: 10.1016/j.undsp.2024.08.004

Guanyu Yan , Chengshun Xu , Zihong Zhang , Xuelai Wang , Xiuli Du

Due to the planning of the subway route, it is difficult to avoid crossing soft soil site conditions at subway stations. The seismic response of subway station structures is closely related to the surrounding soil site. In this paper, centrifuge shaking table tests were designed and carried out for subway station structures at three typical soft soil sites (all-clay site, liquefiable interlayer site, and fully liquefiable site). The test results are as follows. The structure is most severely damaged in all-clay site, while the damage is low in liquefiable interlayer site and fully liquefiable site. For liquefiable sites, site liquefaction results in a lower soil-structure stiffness ratio. Thus liquefiable interlayer site and fully liquefiable site provide a natural seismic isolation system for structures compared to all-clay site. The limits of the inter-story drift ratio of the structure were used to evaluate the post-earthquake performance stages of the model structure in the three sites. In all-clay site, the structure is in the “immediately operational” stage after the loading condition of 0.1g and 0.32g, and in the “reparable operational” stage after the loading condition of 0.52g and 0.72g. In the liquefiable interlayer site and full liquefiable site, the underground structure is in the “normal operational” stage after the loading condition of 0.1g and in the “immediately operational” stage after the loading condition of 0.32g–0.72g.

由于地铁线路的规划，地铁站很难避免穿越软土场地的情况。地铁车站结构的地震响应与周围土质场地密切相关。本文设计并进行了三种典型软土场地（全粘土场地、可液化夹层场地和全可液化场地）的地铁车站结构离心振动台试验。试验结果如下。全粘土地块的结构损坏最严重，而可液化夹层地块和全可液化地块的结构损坏较轻。对于可液化场地，场地液化导致土体-结构刚度比降低。因此，与全粘土地段相比，可液化夹层地段和全液化地段可为结构提供天然的隔震系统。结构的层间漂移比限制用于评估模型结构在三个场地的震后性能阶段。在全粘土场地，结构在 0.1g 和 0.32g 的荷载条件下处于 "立即投入使用 "阶段，在 0.52g 和 0.72g 的荷载条件下处于 "可修复投入使用 "阶段。在可液化夹层地段和完全可液化地段，地下结构在加载 0.1g 条件后处于 "正常运行 "阶段，在加载 0.32g-0.72g 条件后处于 "立即运行 "阶段。

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引用次数: 0

Analysis of hydraulic breakdown and seepage of tail sealing system in shield tunnel machines 盾构隧道机尾部密封系统的液压破坏和渗流分析

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-24 DOI: 10.1016/j.undsp.2024.08.003

Dalong Jin , Zhuoyu Li , Dajun Yuan , Yangyang Gan , Jian Chen , Haipeng Guo

The use of shield method in tunnel construction is limited by the engineering conditions of highwater pressure. This is mainly due to the uncertainty of the pressure-bearing capacity of the sealing chambers of the shield tail under different grades and conditions when subjected to different external water pressures. Therefore, it is crucial to determine the pressure-bearing capacity of the sealing chambers. However, there is a lack of studies on the calculating method of the pressure-bearing capacity, which requires more theoretical investigation. To explore the common patterns of multi-grade sealing-related parameters and quantify the pressure-bearing capacity of the sealing chambers, a breakdown and leakage model of the shield tail is proposed, targeting the basic sealing unit of the system. Based on non-Newtonian fluid dynamics and fractal theory of porous media, the model is used to calculate the breakdown pressure and grease seepage rate corresponding to tunneling and shutdown states. In addition, a hydraulic breakdown device of the sealing unit of the static shield tail is built to investigate the relationship between the shield tail clearance and the shield tail brush porous media area, which helps to verify the theoretical model. Finally, the analysis of sealing chamber geometry parameters, grease rheological parameters, and an environmental parameter using the proposed theoretical model shows that the pressure-bearing capacity of the shield tail can be improved by increasing the shield tail clearance and grease yield stress. It also shows that the length of the sealing chamber and the plastic viscosity of the grease do not have a significant effect on the breakdown pressure of the shield tail. The model proposed in this paper will provide ideas for the calculation of the pressure-bearing capacity of multi-grade sealing chambers in the future.

盾构法在隧道施工中的应用受到高水压工程条件的限制。这主要是由于不同等级和条件下的盾尾密封舱在承受不同外部水压时的承压能力存在不确定性。因此，确定密封腔的承压能力至关重要。然而，有关承压能力计算方法的研究还很缺乏，这需要更多的理论研究。为了探索多级密封相关参数的共同规律，量化密封腔的承压能力，针对系统的基本密封单元，提出了盾尾的击穿和泄漏模型。该模型基于多孔介质的非牛顿流体动力学和分形理论，用于计算隧道状态和停机状态对应的击穿压力和油脂渗漏率。此外，还建立了静态盾尾密封单元的液压击穿装置，研究了盾尾间隙与盾尾刷多孔介质面积之间的关系，有助于验证理论模型。最后，利用所提出的理论模型对密封腔几何参数、润滑脂流变参数和环境参数进行分析，结果表明，通过增加盾尾间隙和润滑脂屈服应力，可以提高盾尾的承压能力。研究还表明，密封腔的长度和润滑脂的塑性粘度对盾尾的击穿压力影响不大。本文提出的模型将为今后计算多级密封腔的承压能力提供思路。

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引用次数: 0

Back analysis of geomechanical parameters based on a data augmentation algorithm and machine learning technique 基于数据增强算法和机器学习技术的地质力学参数回溯分析

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-22 DOI: 10.1016/j.undsp.2024.08.002

Hui Li, Weizhong Chen, Xianjun Tan

Accurate geomechanical parameters are key factors for stability evaluation, disaster forecasting, structural design, and supporting optimization. The intelligent back analysis method based on the monitored information is widely recognized as the most efficient and cost-effective technique for inverting parameters. To address the low accuracy of measured data, and the scarcity of comprehensive datasets, this study proposes an innovative back analysis framework tailored for small sample sizes. We introduce a multi-faceted back analysis approach that combines data augmentation with advanced optimization and machine learning techniques. The auxiliary classifier generative adversarial network (ACGAN)-based data augmentation algorithm is first employed to generate synthetic yet realistic samples that adhere to the underlying probability distribution of the original data, thereby expanding the dataset and mitigating the impact of small sample sizes. Subsequently, we harness the power of optimized particle swarm optimization (OPSO) integrated with support vector machine (SVM) to mine the intricate nonlinear relationships between input and output variables. Then, relying on a case study, the validity of the augmented data and the performance of the developed OPSO-SVM algorithms based on two different sample sizes are studied. Results show that the new datasets generated by ACGAN almost coincide with the actual monitored convergences, exhibiting a correlation coefficient exceeding 0.86. Furthermore, the superiority of the OPSO-SVM algorithm is also demonstrated by comparing the displacement prediction capability of various algorithms through four indices. It is also indicated that the relative error of the predicted displacement values reduces from almost 20% to 5% for the OPSO-SVM model trained with 25 samples and that trained with 625 samples. Finally, the inversed parameters and corresponding convergences predicted by the two OPSO-SVM models trained with different samples are discussed, indicating the feasibility of the combination application of ACGAN and OPSO-SVM in back analysis of geomechanical parameters. This endeavor not only facilitates the progression of underground engineering analysis in scenarios with limited data, but also serves as a pivotal reference for both researchers and practitioners alike.

准确的地质力学参数是稳定性评估、灾害预报、结构设计和配套优化的关键因素。基于监测信息的智能反演分析方法被公认为是最高效、最经济的参数反演技术。针对测量数据准确度低、综合数据集稀缺的问题，本研究提出了一种针对小样本量量身定制的创新反演分析框架。我们引入了一种多方面的回溯分析方法，将数据增强与先进的优化和机器学习技术相结合。首先，我们采用基于辅助分类器生成对抗网络（ACGAN）的数据增强算法，生成符合原始数据基本概率分布的合成但真实的样本，从而扩展数据集，减轻小样本量的影响。随后，我们利用集成了支持向量机（SVM）的优化粒子群优化（OPSO）功能，挖掘输入和输出变量之间错综复杂的非线性关系。然后，我们以案例研究为基础，研究了基于两种不同样本量的增强数据的有效性和所开发的 OPSO-SVM 算法的性能。结果表明，ACGAN 生成的新数据集与实际监测到的收敛数据几乎一致，相关系数超过 0.86。此外，通过四项指标比较各种算法的位移预测能力，也证明了 OPSO-SVM 算法的优越性。结果表明，用 25 个样本训练的 OPSO-SVM 模型和用 625 个样本训练的 OPSO-SVM 模型预测位移值的相对误差从近 20% 降至 5%。最后，讨论了用不同样本训练的两个 OPSO-SVM 模型预测的反演参数和相应的收敛性，表明 ACGAN 和 OPSO-SVM 联合应用于地质力学参数反演分析的可行性。这项工作不仅有助于在数据有限的情况下推进地下工程分析，而且对研究人员和从业人员都具有重要的参考价值。

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引用次数: 0

Interpretable model for rockburst intensity prediction based on Shapley values-based Optuna-random forest 基于 Shapley 值的 Optuna 随机森林的岩爆强度预测可解释模型

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-16 DOI: 10.1016/j.undsp.2024.09.002

Yaxi Shen , Shunchuan Wu , Yongbing Wang , Jiaxin Wang , Zhiquan Yang

To address the limitation of traditional machine learning models in explaining the rockburst intensity prediction process, this study proposes an interpretable rockburst intensity prediction model. The model was developed using 350 sets of actual rockburst sample data to explore the impact of input metrics on the final rockburst intensity level. The collected data underwent pre-processing using the isolation forest algorithm and synthetic minority oversampling technique. The random forest model was optimized through 5-fold cross-validation and the Optuna framework, resulting in the establishment of an Optuna-random forest (Op-RF) model that generates decision rules through its internal decision tree, utilizing the properties of the random forest model. The model was further interpreted using the Shapley additive explanations algorithm, both locally and globally. The results demonstrate that the proposed model achieved an area under curve score of 0.984. In comparison to eight other machine learning models, the proposed Op-RF model demonstrated superior accuracy, precision, recall, and F₁ score. The model provides a transparent explanation of the prediction process, linking impact characteristics to the final output. Additionally, a cloud deployment method for the rockburst intensity prediction model is provided and its effectiveness is demonstrated through engineering verification. The proposed model offers a new approach to the application of machine learning in rockburst intensity prediction.

针对传统机器学习模型在解释岩爆强度预测过程中的局限性，本研究提出了一种可解释的岩爆强度预测模型。该模型使用 350 组实际岩爆样本数据进行开发，以探索输入指标对最终岩爆强度等级的影响。收集到的数据使用隔离林算法和合成少数超采样技术进行了预处理。通过 5 倍交叉验证和 Optuna 框架对随机森林模型进行了优化，最终建立了 Optuna-随机森林（Op-RF）模型，该模型利用随机森林模型的特性，通过内部决策树生成决策规则。利用沙普利加法解释算法对该模型进行了局部和全局的进一步解释。结果表明，所提出的模型的曲线下面积得分达到了 0.984。与其他 8 个机器学习模型相比，所提出的 Op-RF 模型在准确度、精确度、召回率和 F1 分数方面都表现出了优势。该模型透明地解释了预测过程，将影响特征与最终输出联系起来。此外，还提供了岩爆强度预测模型的云部署方法，并通过工程验证证明了其有效性。所提出的模型为机器学习在岩爆强度预测中的应用提供了一种新方法。

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引用次数: 0

Characteristics of deformation and defect of shield tunnel in coastal structured soil in China 中国沿海结构土盾构隧道变形与缺陷特征

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-16 DOI: 10.1016/j.undsp.2024.07.007

Fanyan Meng , Bo Hu , Renpeng Chen , Hongzhan Cheng , Huaina Wu

Shield tunnel is a type of linear underground structure assembled by lining segments, characterized with long joint, weak stiffness, and strict deformation control requirement. The situation of the long-term deformation and defect of the shield tunnel in soft ground in coastal area of China is severe, mainly attributed to the tunneling-induced ground consolidation, frozen cross passage, groundwater pumping, cyclic train load, and nearby construction. Shield tunnel is buried in ground, and the above factors could result in underlying ground settlement, overlying ground loading/unloading, and at-side ground unloading. As a result, the tunnel could suffer from different types of structural deformation and defect. Based upon the aforementioned different reasons, this study investigates the characteristics of the tunnel deformation and defect corresponding to the different types of ground stress change and deformation. It is found that tunneling-induced ground consolidation, frozen cross passage, groundwater pumping, and cyclic train load mainly contribute to the longitudinal differential settlement but negligible transverse convergence, associated with water leakages at circumferential joints. In comparison, surface surcharge and at-side unloading not only cause significant longitudinal differential deformation but also increase transverse lining internal forces, resulting in water leakages at circumferential joints, longitudinal lining concrete cracks and water leakages. Finally, nearby construction could strongly disturb the ground and cause the generation of excess pore-water pressure, making the shield tunnel deformation develops continuously after the nearby construction is completed.

盾构隧道是一种由衬砌分段拼装而成的地下线性结构，具有接头长、刚度弱、变形控制要求严格等特点。我国沿海地区软土地基中盾构隧道的长期变形和缺陷形势严峻，主要原因是掘进引起的地层固结、冻结穿越、地下水抽排、列车循环荷载以及附近施工等。盾构隧道埋于地下，上述因素可能导致地下沉降、上覆地层加载/卸载和边侧地层卸载。因此，隧道可能会出现不同类型的结构变形和缺陷。基于上述不同原因，本研究探讨了不同类型地应力变化和变形所对应的隧道变形和缺陷特征。研究发现，隧道诱发的地层固结、冻结横通道、地下水抽水和列车循环荷载是造成纵向差异沉降的主要原因，而与周向接缝处漏水有关的横向收敛则可以忽略不计。相比之下，地表附加荷载和侧向卸载不仅会造成显著的纵向差异变形，还会增加横向衬砌内力，导致周向接缝处漏水、纵向衬砌混凝土裂缝和漏水。最后，附近施工会强烈扰动地层，导致产生过大的孔隙水压力，使盾构隧道在附近施工结束后变形持续发展。

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引用次数: 0

Numerical analysis of a deep and oversized group excavation: A case study 深层超大群体挖掘的数值分析：案例研究

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-16 DOI: 10.1016/j.undsp.2024.08.001

Mingguang Li , Haobiao Chen , Zhongjie Zhang , Jinjian Chen , Qirun Yang

Group excavations are composed of several individual excavations adjacent to each other with simultaneous or successive construction sequences (CS), which are distinctive from individual excavation in terms of the performance of excavation. In this study, a hyper-scale 3D finite element model was established to investigate the deformation behavior of a diaphragm wall system retaining a deep and oversized group excavation (DOGE) in Shanghai soft clay deposits. The numerical model simulated the practical construction stages and sequences, and it was verified by a series of comparisons with field measurements. Based on the numerical model, the spatial effect of the performance of DOGE in the process of excavation stages was investigated in this study, which cannot be addressed by limited field measurements. Furthermore, the effects of partition walls and CS on the deformation control were discussed to provide practical suggestions for oversized and deep excavations. The results indicate that the employment of bi-partition walls to divide the oversized excavation into several small pits and mono-partition walls and cross walls to further divide the pits near the metro lines into smaller ones, was proved to have significant effectiveness in controlling the wall deflection and protecting the adjacent metro line. For the partition wall, the magnitude and direction of the wall deflection primarily depended on the initial excavation, while the influence of subsequent excavation activities proved insignificant. Thus, it should be noted that the effect of the initial excavation should be especially concentrated. The findings can help optimize similar DOGE engineering.

群挖是由多个相邻的单个开挖点同时或连续施工（CS）组成，在开挖性能上与单个开挖有明显区别。本研究建立了超大规模三维有限元模型，以研究上海软粘土地层中超大深基坑群开挖（DOGE）连续墙系统的变形行为。数值模型模拟了实际施工阶段和顺序，并通过一系列与现场测量的对比进行了验证。在数值模型的基础上，本研究研究了开挖阶段过程中 DOGE 性能的空间效应，而有限的实地测量无法解决这一问题。此外，还讨论了隔墙和 CS 对变形控制的影响，为超大和超深开挖提供了实用建议。研究结果表明，采用双隔墙将超大开挖分成多个小坑，采用单隔墙和十字墙将地铁线附近的坑进一步分成更小的坑，对控制墙体变形和保护邻近地铁线具有显著效果。就隔墙而言，墙体挠度的大小和方向主要取决于最初的挖掘活动，而后续挖掘活动的影响则微乎其微。因此，应特别注意初始开挖的影响。这些发现有助于优化类似的 DOGE 工程。

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引用次数: 0

Effects of the excavation of deep foundation pits on an adjacent double-curved arch bridge 挖掘深基坑对相邻双曲拱桥的影响

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-11 DOI: 10.1016/j.undsp.2024.09.001

Xin Yan , Liyuan Tong , Hongjiang Li , Wenyuan Liu , Yu Xiao , Wei Wang

The excavation of deep foundation pits can cause variations in the displacement and stress fields of surrounding soils, which hence induces adverse effects on adjacent structures. This study presents a two-stage method to quantify the impact of the excavation of a deep foundation pit on the adjacent double-curved arch bridge in the historical city of Nanjing, Southeastern China. The entire process of the foundation pit excavation was simulated and the induced deformation of the arch foot was obtained in the first stage by hardening soil model with small-strain stiffness. Then, the obtained deformation of the arch foot was applied to the bridge structure as a displacement boundary in the second stage to calculate the internal forces and deformations of the double-curved arch bridge structure. The tensile strength of concrete is taken as the limit value of the tensile stress of the double-curved arch bridge. The limit values of arch foot displacement under four evaluation conditions are obtained by step loading calculation. The present results provide construction guidance and safety warning for the process of foundation pit excavation adjacent to double-curved arch bridges for historical preservation.

深基坑的开挖会引起周围土体位移和应力场的变化，从而对相邻结构产生不利影响。本研究采用两阶段法量化了中国东南部历史名城南京的深基坑开挖对相邻双曲拱桥的影响。第一阶段模拟基坑开挖的全过程，并通过具有小应变刚度的硬化土模型获得拱脚的诱导变形。然后，在第二阶段将获得的拱脚变形作为位移边界应用于桥梁结构，计算双曲拱桥结构的内力和变形。以混凝土的抗拉强度作为双曲拱桥的拉应力极限值。通过阶跃加载计算得到了四种评价条件下拱脚位移的极限值。本研究结果为双曲拱桥附近的基坑开挖过程提供了施工指导和安全警示，有利于对双曲拱桥进行历史保护。

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引用次数: 0

Experimental study on mechanical behavior and countermeasures of mountain tunnels under strike-slip fault movement 走向滑动断层运动下的山岭隧道力学行为与对策试验研究

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-03 DOI: 10.1016/j.undsp.2024.07.006

Zhen Wang , Zilan Zhong , Mi Zhao , Xiuli Du , Jingqi Huang , Hongru Wang

In the seismic mountainous regions such as western China, it is usuallly inevitable to construct tunnels near active fault zones. Those fault-crossing tunnel structures can be extremely vulnerable during earthquakes. Extensive experimental studies have been conducted on the response of continuous mountain tunnels under reverse and normal fault movements, limited experimental investigations are available in the literatures on mountain tunnels with special structural measures crossing strike-slip faults. In this study, a new experimental facility for simulating the movement of strike-slip fault was developed, accounting for the spatial deformation characteristics of large active fault zones. Two groups of sandbox experiment were performed on the scaled tunnel models to investigate the evolution of ground deformation and surface rupture subjected to strike-slip fault motion and its impact on a water conveyance tunnel. The nonlinear response and damage mechanism of continuous tunnels and tunnels incorporated with specially designed articulated system were examined. The test results show that most of slip between stationary block and moving block occurred within the fault core, and significant surface ruptures are observed along the fault strike direction at the fault damage zone. The continuous tunnel undergoes significant shrinkage deformation and diagonal-shear failure near the slip surface and resulted in localized collapse of tunnel lining. The segments of articulated system tunnel suffer a significant horizontal deflection of about 5°, which results in opening and misalignment at the flexible joint. The width of the damaged zone of the articulated system tunnel is about 0.44 to 0.57 times that of the continuous tunnel. Compared to continuous tunnels, the articulated design significantly reduces the axial strain response of the tunnel lining, but increases the circumferential tensile strain at the tunnel crown and invert. It is concluded that articulated design provides an effective measure to reduce the extent of damage in mountain tunnel.

在中国西部等地震多发山区，不可避免地要在活动断层带附近修建隧道。这些穿越断层的隧道结构在地震中非常脆弱。关于连续山岭隧道在逆断层和正断层运动下的响应，已经进行了大量的实验研究，但关于具有特殊结构措施的穿越走向滑动断层的山岭隧道的实验研究还很有限。本研究根据大型活动断层带的空间变形特征，开发了一种新的模拟走向滑动断层运动的实验设施。在按比例制作的隧道模型上进行了两组沙盘实验，研究了走向滑动断层运动时地面变形和地表破裂的演变过程及其对输水隧道的影响。试验研究了连续隧道和采用特殊设计的铰接系统的隧道的非线性响应和破坏机理。试验结果表明，静止块体和移动块体之间的大部分滑移发生在断层核心区，在断层破坏区沿断层走向观察到明显的表面破裂。连续隧道在滑移面附近发生了明显的收缩变形和斜切破坏，导致隧道衬砌局部坍塌。铰接式系统隧道的各段发生了约 5° 的显著水平变形，导致柔性连接处开裂和错位。铰接式隧道受损区的宽度约为连续式隧道的 0.44 至 0.57 倍。与连续隧道相比，铰接式设计大大降低了隧道衬砌的轴向应变响应，但增加了隧道顶部和反向的周向拉伸应变。结论是，铰接式设计是减少山区隧道损坏程度的有效措施。

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引用次数: 0

Detecting soil mixing, grain size distribution, and clogging potential of tunnel excavation face by classification-regression algorithms using EPBM operational data 利用 EPBM 运行数据，通过分类-回归算法检测隧道开挖工作面的土壤混合情况、粒度分布和堵塞潜力

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-10-03 DOI: 10.1016/j.undsp.2024.06.007

Sharmin Sarna, Marte Gutierrez

Earth pressure balance machine (EPBM) operation is sensitive to the properties of the excavated soil due to the requirements of proper soil conditioning and maintenance of necessary chamber pressure. However, soil properties are invariably only available at a limited number of borehole explorations and soil samplings conducted during the subsoil investigation. Thus, it is crucial to identify properties of the tunnel excavation face, such as clay-sand mixed conditions, grain size distributions, and clogging potential along the whole alignment beside the few borehole locations to attain optimally efficient EPBM operation. Therefore, this paper presents the development of machine learning prediction models (i.e., classifiers and regressors) to estimate the properties of the tunnel excavation face using EPBM operational data collected during the tunneling operation as input features. Geotechnical data collected from boreholes and soil samples can be used to validate prediction models and calibrate them. To develop such models, the Northgate Link Extension (N125) tunneling project, constructed in Seattle, Washington, the USA, is used to capture and identify the true ground conditions. The results indicate successful prediction performances by the models, providing indication that EPBM parameters are crucial pointers of the tunnel excavation face properties to help attain optimally efficient EPBM operation.

土压平衡机（EPBM）的运行对挖掘土壤的性质非常敏感，因为需要对土壤进行适当的调节并保持必要的腔室压力。然而，在底土勘察过程中，土壤特性往往只能通过有限的钻孔勘探和土壤取样获得。因此，除了少数几个钻孔位置外，确定隧道开挖面的特性（如粘沙混合状况、粒度分布和整个线路的堵塞潜力）对于实现 EPBM 的最佳高效运行至关重要。因此，本文介绍了机器学习预测模型（即分类器和回归器）的开发情况，利用在隧道开挖过程中收集到的 EPBM 运行数据作为输入特征来估计隧道开挖面的属性。从钻孔和土壤样本中收集的岩土工程数据可用于验证预测模型并对其进行校准。为了开发此类模型，我们使用了在美国华盛顿州西雅图市建造的北门连接线延伸段（N125）隧道项目来捕捉和识别真实的地层条件。结果表明，模型的预测性能非常成功，表明 EPBM 参数是隧道开挖面特性的关键指针，有助于实现 EPBM 的最佳高效运行。

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引用次数: 0

Experimental and numerical investigation of the load-bearing capacity of bolt-fastened wedge active joints for prestressed internal bracing in subway excavations 用于地铁挖掘工程预应力内支撑的螺栓紧固楔形活动接头承载能力的实验和数值研究

IF 8.2 1区工程技术 Q1 ENGINEERING, CIVIL

Underground Space

Pub Date : 2024-09-27 DOI: 10.1016/j.undsp.2024.06.006

Chenhe Ge , Pengfei Li , Mingju Zhang , Meng Yang , Weizi Wan

The present study develops a novel type of active joint node-bolt fasten wedge (BFW) active joints, aiming to investigate the load-bearing capacity of a BFW joint in a quantitative way and put forward precise formulas for its yield load and compression rigidity. To achieve this, indoor axial loading tests were conducted on two BFW joints, accompanied by a set of numerical simulations with the finite element approach implemented in ABAQUS. Parametric research was then conducted to assess the impact of various factors on the yield load and initial compression rigidity of BFW joints, leading to the derivation of precise calculation formulas for accurate prediction of these parameters. The key findings indicate that enhancing the bolt strength from 10.9 to 12.9 significantly improves mechanical performance. Under axial compression, the final bearing force, yield load, and initial compression rigidity increase by 0.86, 1.06, and 0.15 times, respectively. Numerical models accurately predict joint behavior under axial force, confirming their reliability. Parameter studies reveal that increasing web and eaves thickness, bolt strength, and diameter improves bearing capacity, while splint thickness has little effect. The fitting formulas introduced can precisely estimate yield load and rigidity, providing practical value for engineering applications.

本研究开发了一种新型节点-螺栓紧固楔（BFW）主动连接，旨在定量研究 BFW 连接的承载能力，并提出其屈服载荷和压缩刚度的精确公式。为此，对两个 BFW 接头进行了室内轴向加载试验，并使用 ABAQUS 中的有限元方法进行了一系列数值模拟。然后进行了参数研究，以评估各种因素对 BFW 接头的屈服载荷和初始压缩刚度的影响，从而推导出精确预测这些参数的精确计算公式。主要研究结果表明，将螺栓强度从 10.9 提高到 12.9 可显著改善机械性能。在轴向压缩条件下，最终承载力、屈服载荷和初始压缩刚度分别增加了 0.86 倍、1.06 倍和 0.15 倍。数值模型准确地预测了轴向力作用下的连接行为，证实了其可靠性。参数研究表明，增加腹板和檐口厚度、螺栓强度和直径可提高承载能力，而夹板厚度影响不大。引入的拟合公式可以精确估算屈服载荷和刚度，为工程应用提供了实用价值。

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