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Comparative analysis between single-train passing and double-train intersection in a tunnel

Journal of Zhejiang University-Science A(Applied Physics & engineering) 2024年第5期25卷 429-442页

作者： Jianming DU Qian FANG Xuan ZHANG Hualao WANG Bridge and tunnel research Center Research Institute of Highway Ministry of TransportBeijing 100088China tunnel and underground engineering research Center of Ministry of Education Beijing Jiaotong UniversityBeijing 00044China

Aerodynamic pressure significantly impacts the scientific evaluation of tunnel service *** aerodynamic pressure of two trains running in a double-track tunnel is considerably more complicated than that of a single *** used the numerical method to investigate the difference in aerodynamic pressure between a single train and two trains running in a double-track ***,the numerical method was verified by comparing the results of numerical simulation and on-site ***,the characteristics of aerodynamic pressure were ***,the influence of various train-tunnel factors on the characteristics of aerodynamic pressure was *** results show that the aerodynamic pressure variation can be divided into stage I:irregular pressure fluctuations before the train tail leaves the tunnel exit,and stage II:periodic pressure declines after the train tail leaves the tunnel *** addition,the aerodynamic pressure simultaneously jumps positively or drops negatively for a single train or two trains running in double-track tunnel *** pressure amplitude in the two-train case is higher than that for a single *** maximum positive peak pressure difference(P_(STP))and maximum negative peak pressure difference(P_(STN))increase as train speed rises to the power from 2.256 to 2.930 in stage *** P_(STP) and P_(STN) first increase and then decrease with the increase of tunnel length in stage *** P_(STP) and P_(STN) increase as the blockage ratio rises to the power from 2.032 to 2.798 in stages I and II.

关键词： Railway tunnel Aerodynamic effect Pressure characteristic Train speed tunnel length Blockage ratio

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Experimental study on workability and permeability of sandy soils conditioned with thickened foam

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Journal of Rock Mechanics and Geotechnical engineering 2024年第2期16卷 532-544页

作者： Zhiyao Feng Shuying Wang Tongming Qu Xiangcou Zheng Fanlin Ling School of Civil engineering Central South UniversityChangsha410075China tunnel and underground engineering research Center Central South UniversityChangsha410075China Department of Civil and Environmental engineering The Hong Kong University of Science and TechnologyClearwater BayKowloon999077Hong KongChina Geo-engineering Section Delft University of TechnologyDelft999025Netherlands

Water spewing and muck plugging often occur during earth pressure balance(EPB)shield machines tunnelling in water-rich sandy strata,even though the conventional foam has been employed to condition sandy *** this study,a novel thickened foaming agent suitable for EPB shield tunnelling in water-rich sandy strata is *** contrast to conventional foam-conditioned sands,the thickened foam-conditioned sand has a low permeability due to the consistent filling of soil pores with the thickened foam,and the initial permeability coefficient decreases by approximately two orders of *** also exhibits a suitable workability,which is attributed to the enhanced capability of the thickened foam to condition sandy *** addition,the effect of concentration on the stability of the foam is explained by the Gibbs-Marangoni effect,and conditioning mechanisms for the thickened foam on sands are discussed from the evolution of foam bubbles.

关键词： Earth pressure balance(EPB)shield Thickened foam Foam-conditioned sand Permeability Workability

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二氧化碳静态爆破的边坡振动场地效应和能量分析

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Journal of Central South University 2024年第1期31卷 210-224页

作者：王小飞胡少斌王恩元 School of Safety engineering China University of Mining and TechnologyXuzhou 221116China tunnel and underground engineering institute College of Civil and Transportation EngineeringHohai UniversityNanjing 210098China

进行真三轴CO_(2)静态爆破压裂实验和现场测试,获得压力曲线、试样裂隙分布、现场振动曲线和岩体破坏特征,并通过分析压力曲线和裂缝扩展特征来研究致裂原理,同时还利用窗函数傅里叶变换提取振动特征,以评估破岩现场边坡的结构安全。研... 详细信息

进行真三轴CO_(2)静态爆破压裂实验和现场测试,获得压力曲线、试样裂隙分布、现场振动曲线和岩体破坏特征,并通过分析压力曲线和裂缝扩展特征来研究致裂原理,同时还利用窗函数傅里叶变换提取振动特征,以评估破岩现场边坡的结构安全。研究结果表明:(1)CO_(2)静态爆破的峰值振动速度在8 m处衰减至满足建筑物保护要求,比传统的钻爆法更安全;(2)CO_(2)静态爆破引起的振动波形的主频高于钻爆法的,且随着距离的加长,振动能量的分布逐渐分散;(3)钻爆法的振动速度预测公式适用于CO_(2)静态爆破的,且带高程的预测公式更为准确。根据压力曲线、试样裂隙分布和现场岩体损伤,提出CO_(2)静态爆破的HIG破岩模型,为新技术的研究提供了基础框架。在实验中没有采集到温度数据,今后迫切需要对聚能剂的瞬时放热特性和温度对CO_(2)状态的影响进行研究。

关键词：破岩技术二氧化碳静态爆破振动速度致裂机理能量计算

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Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks

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Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2629-2644页

作者： Xiongyu Hu Marte Gutierrez Zhiwei Yan Key Laboratory of Transportation tunnel engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu610031China University Transportation Center for underground Transportation Infrastructure Colorado School of MinesGoldenUSA School of Civil engineering Southwest Jiaotong UniversityChengdu610031China

From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative *** of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary ***,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary ***,the literature does not document the suitability of different models for specific *** challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain *** aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact *** and biaxial compression tests are performed to calibrate the response of Creighton *** stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are *** was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock ***,the LPB model is unable to reproduce the post-peak *** to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain *** overestimates the volumetric dilation and residual shear *** LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure.

关键词： Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock

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Development of multi-functional anchorage support dynamic-static coupling performance test system and its application

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International Journal of Mining Science and Technology 2024年第3期34卷 339-349页

作者： Qi Wang Shuo Xu Bei Jiang Chong Zhang Zhe Sun Jingxuan Liu Cailin Jiao State Key Laboratory for tunnel engineering China University of Mining&Technology-BeijingBeijing 100083China research Center of Geotechnical and Structural engineering Shandong UniversityJinan 250061China

In underground engineering with complex conditions,the bolt(cable)anchorage support system is in an environment where static and dynamic stresses coexist,under the action of geological conditions such as high stresses and strong disturbances and construction conditions such as the application of high *** is essential to study the support components performance under dynamic-static coupling *** on this,a multi-functional anchorage support dynamic-static coupling performance test system(MAC system)is developed,which can achieve 7 types of testing functions,including single component performance,anchored net performance,anchored rock performance and so *** bolt and cable mechanical tests are conducted by MAC system under different prestress *** results showed that compared to the non-prestress condition,the impact resistance performance of prestressed bolts(cables)is significantly *** the prestress range of 50–160 k N,the maximum reduction rate of impact energy resisted by different types of bolts is 53.9%–61.5%compared to non-prestress *** the prestress range of 150–300 k N,the impact energy resisted by high-strength cable is reduced by76.8%–84.6%compared to non-prestress *** MAC system achieves dynamic-static coupling performance test,which provide an effective means for the design of anchorage support system.

关键词： Anchorage support system Development of test system Dynamic-static coupling test Combined stress

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Triaxial mechanical properties and precursors of instability damage in rocks with different laminar dip angles

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Journal of Mountain Science 2024年第2期21卷 648-661页

作者： SUN Xiaoming SHI Fukun DING Jiaxu TAO Zhigang HE Linsen YANG Liu ZHANG Yong MIAO Chengyu Inner Mongolia research institute China University of Mining and Technology(Beijing)Beijing 100083China State Key Laboratory for tunnel engineering China University of Mining and Technology(Beijing)Beijing 100083China

To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers in the Junggar Basin,*** changing the confining pressure,we compared the mechanical properties,acoustic emission characteristics,and fractal features of the acoustic emission sequence for volcanic breccia with different bedding dip *** research results indicate that as the bedding dip angle increases,peak strength,internal friction angle,and cohesion exhibit a“U-shaped”variation *** correlation dimension of the acoustic emission amplitude was calculated using the G-P algorithm,revealing that volcanic breccia exhibits fractal ***,a positive correlation between the correlation dimension and the bedding dip angle was *** the stress of the test specimen reaches 0.8σ_(c),there is a significant decrease in the fractal dimension,serving as a criterion for predicting the failure of the *** analyzing the changes in fractal dimension at different stress levels,the slope of the fractal dimension△D<-0.5 can be used as a precursor to failure for test specimens with a bedding dip angle of 15°≤β≤45°.Similarly,when the bedding dip angle of the specimen is 0°≤β<15°or 45°<β≤90°,△D<0 can be considered as a precursor to specimen *** study provides theoretical references for understanding the failure patterns of volcanic rock.

关键词： Volcanic breccia Bedding dip Acoustic emission Fractal dimension Harbinger of destruction

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An improved elastoplastic model for rocks and application to cyclic loading and unloading triaxial compression tests

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Acta Mechanica Sinica 2024年第8期40卷 179-193页

作者： Qiuxin Gu Qiang Zhang Yapeng Li Peinan Wu Guilei Han State Key Laboratory for Geomechanics and Deep underground engineering School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou221116China North China engineering Investigation institute Shijiazhuang050021China

The recoverable strain of rock is completely classified as elastic strain in the conventional elastic-plastic theory,which often results in poor agreement between theoretical and experimental *** work proposes an improved elastoplastic model of rock materials considering the evolutions of crack deformation and elastic modulus to better characterize the nonlinear mechanical behavior of rock in the post-peak *** this model,the recoverable strain is assumed to be a combination of elastic and crack strain,and the constitutive relationship between crack strain and rock stress is *** on the proposed assumption,the evolutions of the mechanical parameters including strength parameters,elastic,plastic,and crack deformation parameters versus the plastic strain and confining stress were *** developed elastoplastic model was validated by comparing the theoretical values with the results of the triaxial cyclic loading and unloading *** theoretical calculation results show a good agreement with the laboratory test,which indicates that the improved elastoplastic model can effectively reflect the nonlinear mechanical behavior of the rock *** research results are expected to provide a valuable reference for further understanding the evolution of rock crack deformation.

关键词： Crack strain Elastic modulus deterioration Novel elastoplastic model Model validation

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Centrifuge modeling of a large-scale surcharge on adjacent foundation

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Journal of Rock Mechanics and Geotechnical engineering 2024年第8期16卷 3181-3191页

作者： Jinzhang Zhang Zhenwei Ye Dongming Zhang Hongwei Huang Shijie Han Tong Zou Le Zhang Key Laboratory of Geotechnical and underground engineering of Ministry of Education and Department of Geotechnical engineering Tongji UniversityShanghai200092China CCCC Third Harbor Consultants Co LtdShanghai200032China Qingdao Conson Jiaozhou Bay Second Subsea tunnel Co. LtdQingdao266000China

This study investigates the ground and structural response of adjacent raft foundations induced by largescale surcharge by ore in soft soil areas through a 130g centrifuge modeling test with an innovative layered loading *** prototype of the test is a coastal iron ore yard with a natural foundation of deep soft ***,it is necessary to adopt some measures to reduce the influence of the large-scale surcharge on the adjacent raft foundation,such as installing stone columns for foundation *** an acceleration of 130 g,the model conducts similar simulations of iron ore,stone columns,and raft foundation *** tested soil mass has dimensions of 900 mm×700 mm×300 mm(lengthwidthdepth),which is remodeled from the soil extracted from the drilling *** test conditions are consistent with the actual engineering conditions and the effects of four-level loading conditions on the composite foundation of stone columns,unreinforced zone,and raft foundations are *** automatic layer-by-layer loading device was innovatively developed to simulate the loading process of actual engineering more *** composite foundation of stone columns had a large settlement after the loading,forming an obvious settlement trough and causing the surface of the unreinforced zone to *** 12 m surcharge loading causes a horizontal displacement of 13.19 cm and a vertical settlement of 1.37 m in the raft *** stone columns located on both sides of the unreinforced zone suffered significant shear damage at the sand-mud *** to the reinforcement effect of stone columns,the sand layer below the top of the stone columns moves ***,the horizontal earth pressure in the raft foundation zone increases *** stone columns will form new drainage channels and accelerate the dissipation of excess pore pressure.

关键词： Centrifuge modeling Stone column Composite foundation Ground movement Raft foundation

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Drilling-based measuring method for the c-φ parameter of rock and its field application

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International Journal of Mining Science and Technology 2024年第1期34卷 65-76页

作者： Bei Jiang Fenglin Ma Qi Wang Hongke Gao Dahu Zhai Yusong Deng Chuanjie Xu Liangdi Yao State Key Laboratory for tunnel engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China research Center of Geotechnical and Structural engineering Shandong UniversityJinan 250061China

The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(RCZ) is built. The formula for an ultimate cutting force is established based on the limit equilibrium principle. The relationship between digital drilling parameters(DDP) and the c-φ parameter(DDP-cφ formula, where c refers to the cohesion and φ refers to the internal friction angle) is derived, and the response of drilling parameters and cutting ratio to the strength parameters is analyzed. The drillingbased measuring method for the c-φ parameter of rock is constructed. The laboratory verification test is then completed, and the difference in results between the drilling test and the compression test is less than 6%. On this basis, in-situ rock drilling tests in a traffic tunnel and a coal mine roadway are carried out, and the strength parameters of the surrounding rock are effectively tested. The average difference ratio of the results is less than 11%, which verifies the effectiveness of the proposed method for obtaining the strength parameters based on digital drilling. This study provides methodological support for field testing of rock strength parameters.

关键词： Digital drilling Rock crushing zone c-u parameter Measurement method Field application

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Seismic responses of an intensively constructed metro station-passageway-shaft structure system

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Frontiers of Structural and Civil engineering 2024年第5期18卷 760-775页

作者： Ruohan LI Yong YUAN Hong CHEN Xinxing LI Emilio BILOTTA Department of Geotechnical engineering Tongji UniversityShanghai 200092China Department of Civil Architectural and Environmental EngineeringUniversity of Naples Federico IINaples 80125Italy State Key Laboratory of Disaster Reduction in Civil engineering Tongji UniversityShanghai 200092China Shanghai tunnel engineering&Rail Transit Design and research institute Shanghai 200235China

Intensive construction methods offer benefits for metro station development,yet they present challenges for seismic design due to the spatially asymmetric configuration of passageway-shaft *** this study,a detailed numerical model of a station-passageway-shaft structure system built using intensive construction methods was developed and the deformation and damage modes under seismic loadings were *** results indicate that inconsistent deformation between the shaft and the station generates interaction through the connecting passageway,leading to damage near the opening of the station structure and both ends of the connecting passageway Damage is more severe under longitudinal *** with the opening plan that spans four segments,the opening plan that spans five segments exacerbates the overall degree of damage to the structure *** transverse excitation,the presence of interior structures intensifies the damage to the station and connecting passageway,while with such internal structure in place the impact is relatively minor under longitudinal *** with steel segments near the station opening can appreciably attenuate the *** contrast,introducing flexible joints at both ends of the connecting passageway intensifies the ***,reinforcement using steel segments emerges as an optimal seismic mitigation strategy.

关键词： earthquake intensive construction metro station numerical simulation

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