Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM)....Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.展开更多
When shield TBM tunnelling in abrasive sandy ground,the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling efficiency.However,the influence mechanism of cutter parameters on sc...When shield TBM tunnelling in abrasive sandy ground,the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling efficiency.However,the influence mechanism of cutter parameters on scraper wear remains unclear due to the lack of a reliable test method.Geometry and material optimisation are often based on subjective experience,which is unfavourable for improving scraper geological adaptability.In the present study,the newly developed WHU-SAT soil abrasion test was used to evaluate the variation in scraper wear with cutter geometry,material and hardness.The influence mechanism of cutter parameters on scraper wear has been revealed according to the scratch characteristics of the scraper surface.Cutter geometry and material parameters have been optimised to reduce scraper wear.The results indicate that the variation in scraper wear with cutter geometry is related to the cutting resistance,frictional resistance and stress distribution.An appropriate increase in the front angle(or back angle)reduces the cutting resistance(or frictional resistance),while an excessive increase in the front angle(or back angle)reduces the edge angle and causes stress concentration.The optimal front angle,back angle and edge angle for quartz sand samples areα=25°,β=10°andγ=55°,respectively.The wear resistance of the modelled scrapers made of different metal materials is related to the chemical elements and microstructure.The wear resistances of the modelled scrapers made of 45#,06Cr19Ni10,42CrMo4 and 40CrNiMoA are 0.569,0.661,0.691 and 0.728 times those made of WC-Co,respectively.When the alloy hardness is less than 47 HRC(or greater than 58 HRC),scraper wear decreases slowly with increasing alloy hardness as the scratch depth of the particle asperity on the metal surface stabilizes at a high(or low)level.However,when the alloy hardness is between 47 HRC and 58 HRC,scraper wear decreases rapidly with increasing alloy hardness as the scratch depth transitions from high to low levels.The sensitive hardness interval and recommended hardness interval for quartz sand are[47,58]and[58,62],respectively.The present study provides a reference for optimising scraper parameters and improving cutterhead adaptability in abrasive sandy ground tunnelling.展开更多
A preliminary shielding analysis on the transport of the Chinese helium cooled ceramic breeder test blanket module（HCCB TBM） from France back to China after being irradiated in ITER is presented in this contribution...A preliminary shielding analysis on the transport of the Chinese helium cooled ceramic breeder test blanket module（HCCB TBM） from France back to China after being irradiated in ITER is presented in this contribution.Emphasis was placed on irradiation safety during transport.The dose rate calculated by MCNP/4C for the conceptual package design satisfies the relevant dose limits from IAEA that the dose rate 3 m away from the surface of the package containing low specific activity III materials should be less than 10 mSv/h.The change with location and the time evolution of dose rates after shutdown have also been studied.This will be helpful for devising the detailed transport plan of HCCB TBM back to China in the near future.展开更多
为实现更精确、更实时的智能围岩分级以匹配双护盾TBM高效掘进,基于先进的HRNet高分辨率神经网络,通过分析地质与掘进参数2类指标的强关联性,构建基于该2类指标融合的高分辨率TBM隧道双模态围岩精准智能分级模型,开展实时的围岩分级工...为实现更精确、更实时的智能围岩分级以匹配双护盾TBM高效掘进,基于先进的HRNet高分辨率神经网络,通过分析地质与掘进参数2类指标的强关联性,构建基于该2类指标融合的高分辨率TBM隧道双模态围岩精准智能分级模型,开展实时的围岩分级工作。结果表明:1)推进速度与刀盘转矩2个参数与围岩坚硬度有较强的关联性,通过这2个掘进参数二维组合的线性趋势以及拐点区间可以区分不同的岩石坚硬程度;2)刀盘滚动角和撑靴俯仰角2个参数与岩体完整性有较强的关联性,通过这2个掘进参数的摆动幅度和角度可区分不同的岩体完整性;3)通过将2个模态单一的HRNet高分辨率神经网络进行拼接和全连接,构建的双模态围岩分级模型能够实现离散型数值的地质模态数据与连续型数值的掘进模态数据融合,该模型能够从围岩稳定性与岩机交互等多方面更加精确地反映围岩分级,应用准确率可达95.0%;4)相比仅用掘进指标的单模态模型,双模态模型在测试集上表现效果更好,其Macro F1 Score为0.985。展开更多
基金Alexander von Humboldt-Foundation (AvH) for the financial support as a research fellowthe financial support of the Scientific and Technological Research Council of Turkey (TüB_ITAK) under Project No. MAG-114M568
文摘Severe shield jamming events have been reported during excavation of Uluabat tunnel through adverse geological conditions, which resulted in several stoppages at advancing a single shielded tunnel boring machine(TBM). To study the jamming mechanism, three-dimensional(3D) simulation of the machine and surrounding ground was implemented using the finite difference code FLAC3D. Numerical analyses were performed for three sections along the tunnel with a higher risk for entrapment due to the combination of overburden and geological conditions. The computational results including longitudinal displacement contours and ground pressure profiles around the shield allow a better understanding of ground behavior within the excavation. Furthermore, they allow realistically assessing the impact of adverse geological conditions on shield jamming. The calculated thrust forces, which are required to move the machine forward, are in good agreement with field observations and measurements. It also proves that the numerical analysis can effectively be used for evaluating the effect of adverse geological environment on TBM entrapments and can be applied to prediction of loads on the shield and preestimating of the required thrust force during excavation through adverse ground conditions.
基金The support provided by the National Natural Science Foundation of Youth Fund Project of China(Grant No.52308415)Key Research and Development Program of Hubei Province,China(Grant No.2021BCA154)Natural Science Foundation of Hubei Province,China(Grant No.2021CFA081)is gratefully acknowledged.
文摘When shield TBM tunnelling in abrasive sandy ground,the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling efficiency.However,the influence mechanism of cutter parameters on scraper wear remains unclear due to the lack of a reliable test method.Geometry and material optimisation are often based on subjective experience,which is unfavourable for improving scraper geological adaptability.In the present study,the newly developed WHU-SAT soil abrasion test was used to evaluate the variation in scraper wear with cutter geometry,material and hardness.The influence mechanism of cutter parameters on scraper wear has been revealed according to the scratch characteristics of the scraper surface.Cutter geometry and material parameters have been optimised to reduce scraper wear.The results indicate that the variation in scraper wear with cutter geometry is related to the cutting resistance,frictional resistance and stress distribution.An appropriate increase in the front angle(or back angle)reduces the cutting resistance(or frictional resistance),while an excessive increase in the front angle(or back angle)reduces the edge angle and causes stress concentration.The optimal front angle,back angle and edge angle for quartz sand samples areα=25°,β=10°andγ=55°,respectively.The wear resistance of the modelled scrapers made of different metal materials is related to the chemical elements and microstructure.The wear resistances of the modelled scrapers made of 45#,06Cr19Ni10,42CrMo4 and 40CrNiMoA are 0.569,0.661,0.691 and 0.728 times those made of WC-Co,respectively.When the alloy hardness is less than 47 HRC(or greater than 58 HRC),scraper wear decreases slowly with increasing alloy hardness as the scratch depth of the particle asperity on the metal surface stabilizes at a high(or low)level.However,when the alloy hardness is between 47 HRC and 58 HRC,scraper wear decreases rapidly with increasing alloy hardness as the scratch depth transitions from high to low levels.The sensitive hardness interval and recommended hardness interval for quartz sand are[47,58]and[58,62],respectively.The present study provides a reference for optimising scraper parameters and improving cutterhead adaptability in abrasive sandy ground tunnelling.
基金supported by the Major State Basic Research Development Program of China(973 Program)(No.2013GB108000)
文摘A preliminary shielding analysis on the transport of the Chinese helium cooled ceramic breeder test blanket module（HCCB TBM） from France back to China after being irradiated in ITER is presented in this contribution.Emphasis was placed on irradiation safety during transport.The dose rate calculated by MCNP/4C for the conceptual package design satisfies the relevant dose limits from IAEA that the dose rate 3 m away from the surface of the package containing low specific activity III materials should be less than 10 mSv/h.The change with location and the time evolution of dose rates after shutdown have also been studied.This will be helpful for devising the detailed transport plan of HCCB TBM back to China in the near future.
文摘为实现更精确、更实时的智能围岩分级以匹配双护盾TBM高效掘进,基于先进的HRNet高分辨率神经网络,通过分析地质与掘进参数2类指标的强关联性,构建基于该2类指标融合的高分辨率TBM隧道双模态围岩精准智能分级模型,开展实时的围岩分级工作。结果表明:1)推进速度与刀盘转矩2个参数与围岩坚硬度有较强的关联性,通过这2个掘进参数二维组合的线性趋势以及拐点区间可以区分不同的岩石坚硬程度;2)刀盘滚动角和撑靴俯仰角2个参数与岩体完整性有较强的关联性,通过这2个掘进参数的摆动幅度和角度可区分不同的岩体完整性;3)通过将2个模态单一的HRNet高分辨率神经网络进行拼接和全连接,构建的双模态围岩分级模型能够实现离散型数值的地质模态数据与连续型数值的掘进模态数据融合,该模型能够从围岩稳定性与岩机交互等多方面更加精确地反映围岩分级,应用准确率可达95.0%;4)相比仅用掘进指标的单模态模型,双模态模型在测试集上表现效果更好,其Macro F1 Score为0.985。
