Underground Space最新文献

{"title":"Characteristics of deformation and defect of shield tunnel in coastal structured soil in China","authors":"Fanyan Meng ,&nbsp;Bo Hu ,&nbsp;Renpeng Chen ,&nbsp;Hongzhan Cheng ,&nbsp;Huaina Wu","doi":"10.1016/j.undsp.2024.07.007","DOIUrl":"10.1016/j.undsp.2024.07.007","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 131-148"},"PeriodicalIF":8.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655939","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}

{"title":"Numerical analysis of a deep and oversized group excavation: A case study","authors":"Mingguang Li ,&nbsp;Haobiao Chen ,&nbsp;Zhongjie Zhang ,&nbsp;Jinjian Chen ,&nbsp;Qirun Yang","doi":"10.1016/j.undsp.2024.08.001","DOIUrl":"10.1016/j.undsp.2024.08.001","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 178-197"},"PeriodicalIF":8.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705114","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}

{"title":"Effects of the excavation of deep foundation pits on an adjacent double-curved arch bridge","authors":"Xin Yan ,&nbsp;Liyuan Tong ,&nbsp;Hongjiang Li ,&nbsp;Wenyuan Liu ,&nbsp;Yu Xiao ,&nbsp;Wei Wang","doi":"10.1016/j.undsp.2024.09.001","DOIUrl":"10.1016/j.undsp.2024.09.001","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 164-177"},"PeriodicalIF":8.2,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705113","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}

{"title":"Experimental study on mechanical behavior and countermeasures of mountain tunnels under strike-slip fault movement","authors":"Zhen Wang ,&nbsp;Zilan Zhong ,&nbsp;Mi Zhao ,&nbsp;Xiuli Du ,&nbsp;Jingqi Huang ,&nbsp;Hongru Wang","doi":"10.1016/j.undsp.2024.07.006","DOIUrl":"10.1016/j.undsp.2024.07.006","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 1-21"},"PeriodicalIF":8.2,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554942","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}

{"title":"Detecting soil mixing, grain size distribution, and clogging potential of tunnel excavation face by classification-regression algorithms using EPBM operational data","authors":"Sharmin Sarna,&nbsp;Marte Gutierrez","doi":"10.1016/j.undsp.2024.06.007","DOIUrl":"10.1016/j.undsp.2024.06.007","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"20 ","pages":"Pages 311-354"},"PeriodicalIF":8.2,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444854","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}

{"title":"Experimental and numerical investigation of the load-bearing capacity of bolt-fastened wedge active joints for prestressed internal bracing in subway excavations","authors":"Chenhe Ge ,&nbsp;Pengfei Li ,&nbsp;Mingju Zhang ,&nbsp;Meng Yang ,&nbsp;Weizi Wan","doi":"10.1016/j.undsp.2024.06.006","DOIUrl":"10.1016/j.undsp.2024.06.006","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 100-116"},"PeriodicalIF":8.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656031","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}

{"title":"Numerical studies on the synergistic effects of smoke extraction and control performance by mechanical ventilation shafts during tunnel fires","authors":"Bin Zhu ,&nbsp;Haiyong Cong ,&nbsp;Zhuyu Shao ,&nbsp;Hairuo Hu ,&nbsp;Lili Ye ,&nbsp;Yubo Bi ,&nbsp;Yiping Zeng","doi":"10.1016/j.undsp.2024.07.005","DOIUrl":"10.1016/j.undsp.2024.07.005","url":null,"abstract":"<div><div>High smoke extraction efficiency and a relatively stable smoke layer stratification are both expected in tunnel ventilation systems. The purpose of this paper is to explore the overall performance of mechanical board-coupled shaft under different ventilation strategies. A total of 57 simulations were conducted, and the effects of the distance between the shaft and board (<span><math><mrow><msub><mi>h</mi><mi>D</mi></msub></mrow></math></span>) and ventilation velocity on the overall performance were investigated. The results indicate that the performance of smoke extraction and control will be improved by the application of mechanical ventilation and board. Smoke movement patterns under different working conditions were different, for cases of <span><math><mrow><msub><mi>h</mi><mi>D</mi></msub><mo>≤</mo><mn>0.40</mn><mspace></mspace><mi>m</mi></mrow></math></span> the smoke could propagate through the whole tunnel without backflow, while for cases of <span><math><mrow><msub><mi>h</mi><mi>D</mi></msub><mo>&gt;</mo><mn>0.40</mn><mspace></mspace><mi>m</mi></mrow></math></span>, the backflow exists and the smoke movement can be separated into three periods (propagation, stagnation, and retraction). The critical criterion of backflow was investigated and a simple model was deduced to estimate the maximum propagation length. Moreover, the dimensionless time for the smoke flow to reach its maximum propagation length was established. Finally, a comprehensive index <span><math><mrow><mi>φ</mi></mrow></math></span> was proposed to evaluate the synergistic effects of smoke extraction and control performance. These studies may provide positive significance for the ventilation design.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 44-64"},"PeriodicalIF":8.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656029","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}

{"title":"Coal-rock interface real-time recognition based on the improved YOLO detection and bilateral segmentation network","authors":"Shuzhan Xu ,&nbsp;Wanming Jiang ,&nbsp;Quansheng Liu ,&nbsp;Hongsheng Wang ,&nbsp;Jun Zhang ,&nbsp;Jinlong Li ,&nbsp;Xing Huang ,&nbsp;Yin Bo","doi":"10.1016/j.undsp.2024.07.003","DOIUrl":"10.1016/j.undsp.2024.07.003","url":null,"abstract":"<div><div>To improve the accuracy and efficiency of coal-rock interface recognition, this study proposes a model built on the real-time detection algorithm, you only look once (YOLO), and the lightweight bilateral segmentation network. Simultaneously, the regional similarity transformation function and dragonfly algorithm are introduced to enhance the quality of coal-rock images. The comparison with three other models demonstrates the superior edge inference performance of the proposed model, achieving a mean Average Precision (mAP) of 90.2 at the Intersection over Union (IoU) threshold of 0.50 (mAP₅₀) and 81.4 across a range of IoU thresholds from 0.50 to 0.95 (mAP_[50,95]). Furthermore, to maintain high accuracy and real-time recognition capabilities, the proposed model is optimized using the open visual inference and neural network optimization toolkit, resulting in a 144.97% increase in the mean frames per second. Experimental results on four actual coal faces confirm the efficacy of the proposed model, showing a better balance between accuracy and efficiency in coal-rock image recognition, which supports further advancements in coal mining intelligence.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 22-43"},"PeriodicalIF":8.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656028","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}

{"title":"Experimental investigation on damage development and failure mechanism of shield tunnel lining under internal blast considering stratum-structure interaction","authors":"Chao Liu ,&nbsp;Guanhua Zhao ,&nbsp;Yijie Liu ,&nbsp;Jie Cui ,&nbsp;Hai Liu ,&nbsp;Shunhang Zhu","doi":"10.1016/j.undsp.2024.07.004","DOIUrl":"10.1016/j.undsp.2024.07.004","url":null,"abstract":"<div><div>With the expansion of international terrorism and the potential threat of attacks against civil infrastructure, the dynamic response and failure modes of underground tunnels under explosive loads have become a prominent research topic. The high cost and inherent danger associated with explosion experiments have limited current research on tunnel internal explosions, particularly in the context of scaled model tests of shield tunnels. This study presents a series of scaled model tests under 1<em>g</em>-condition simulating internal blast events within a shield tunnel based on the prototype of the Shantou Bay Tunnel, considering the influences of surrounding stratum and equivalent explosive yield. Three different TNT explosive yields are considered in the model tests, namely 0.2, 0.4, and 1.0 kg. The model tests focus on the damage behavior and collapse modes of the shield tunnel lining under internal explosive loads. The model tests reveal that the shield tunnel is prone to damage at the joints of the tunnel crown and shoulder when subjected to internal explosive loads, with the upper half of the tunnel lining experiencing segment collapse, while the lower half remains largely undamaged. As the TNT equivalent increases, the damage area at the tunnel joints expands, and the number of segment failures in the upper half of the tunnel rises, transitioning from a damaged state to a collapsed state. The influence of “stratum-structure” interaction is investigated by comparing two models, one with overburden soil and the other positioned at the ground surface. The model tests reveal that the presence of soil pressure and confinement can significantly enhance the tunnel resistance to internal blast loads. Based on the observation of the model tests, five different damage modes of segment joints under internal explosion are proposed in this study.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"21 ","pages":"Pages 81-99"},"PeriodicalIF":8.2,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656030","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}

{"title":"RM2D: An automated and robust laser-based framework for mobile tunnel deformation detection","authors":"Boxun Chen ,&nbsp;Ziyu Zhao ,&nbsp;Lin Bi ,&nbsp;Zhuo Wang","doi":"10.1016/j.undsp.2024.07.002","DOIUrl":"10.1016/j.undsp.2024.07.002","url":null,"abstract":"<div><div>As mining operations extend to greater depths, the risk of deformation in high-stress tunnels increases significantly, posing a substantial threat. This study introduces a novel framework known as “robust mobility deformation detection” (RM2D), designed for real-time tunnel deformation detection. RM2D employs mobile LiDAR scanner to capture real-time point cloud data within the tunnel. This data is then voxelized and analyzed using covariance matrices to create a voxel-based multi-distribution representation of the rugged tunnel surface. Leveraging this representation, we assess deformations and scrutinize results through machine learning models to swiftly pinpoint tunnel deformation locations. Extensive experimental validation confirms the framework’s capacity to successfully detect deformations, including floor heave, side rib spalling, and roof fall, with remarkable accuracy. For deformation levels at 0.15 m, RM2D was able to successfully detect deformations with an area greater than 2 m². For deformation areas of (3 ± 0.5) m², RM2D successfully detected deformations of levels at (0.05 ± 0.01) m, and its detection capability meets the standard criteria for mining tunnel deformation detection. When compared to two conventional methods, RM2D demonstrates its real-time deformation detection capability in complex environments and on rough surfaces with precision, all at speeds below 10 km/h. Furthermore, we evaluated the predictive performance using multiple evaluation metrics and provided insights into the decision mechanism of the machine learning employed in our research, thereby offering valuable information for practical engineering applications in tunnel deformation detection.</div></div>","PeriodicalId":48505,"journal":{"name":"Underground Space","volume":"20 ","pages":"Pages 241-258"},"PeriodicalIF":8.2,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327068","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}