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Pan Yucong Liu Quansheng Kong Xiaoxuan Liu Jianping Peng Xingxin Liu Qi 《Acta Geotechnica》2019,14(4):1249-1268
In this study, determination of some machine parameters and performance prediction for tunnel boring machine (TBM) are conducted based on laboratory rock cutting test. Firstly, laboratory full-scale linear cutting test is carried out using 432-mm CCS (constant cross section) disc cutter in Chongqing Sandstone. Then, the input parameters for TBM cutterhead design are extracted; some TBM specifications are determined and then compared to the manufactured values. Finally, laboratory full-scale linear cutting test results are compared with the field TBM excavation performance data collected in Chongqing Yangtze River Tunnel. Results show that laboratory full-scale linear cutting test results, combined with some engineering considerations, can be used for the preliminary and rough design of TBM machine capacity. Meanwhile, combined with some modification factors, it can also well predict the field TBM excavation performance.
相似文献3.
When planning a TBM drive in squeezing ground, the tunnelling engineer faces a complex problem involving a number of conflicting factors. In this respect, numerical analyses represent a helpful decision aid as they provide a quantitative assessment of the effects of key parameters. The present paper investigates the interaction between the shield, ground and tunnel support by means of computational analysis. Emphasis is placed on the boundary condition, which is applied to model the interface between the ground and the shield or tunnel support. The paper also discusses two cases, which illustrate different methodical approaches applied to the assessment of a TBM drive in squeezing ground. The first case history—the Uluabat Tunnel (Turkey)—mainly involves the investigation of TBM design measures aimed at reducing the risk of shield jamming. The second case history—the Faido Section of the Gotthard Base Tunnel (Switzerland)—deals with different types of tunnel support installed behind a gripper TBM. 相似文献
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When planning a TBM drive in squeezing ground, the tunnelling engineer faces a complex problem involving a number of conflicting
factors. In this respect, numerical analyses represent a helpful decision aid as they provide a quantitative assessment of
the effects of key parameters. The present paper investigates the interaction between the shield, ground and tunnel support
by means of computational analysis. Emphasis is placed on the boundary condition, which is applied to model the interface
between the ground and the shield or tunnel support. The paper also discusses two cases, which illustrate different methodical
approaches applied to the assessment of a TBM drive in squeezing ground. The first case history—the Uluabat Tunnel (Turkey)—mainly
involves the investigation of TBM design measures aimed at reducing the risk of shield jamming. The second case history—the
Faido Section of the Gotthard Base Tunnel (Switzerland)—deals with different types of tunnel support installed behind a gripper
TBM. 相似文献
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Flow characteristics in the vicinity of the flap of a single-slotted airfoil are presented and analysed. The flow remained attached over the model surfaces except in the vicinity of the flap trailing edge where a small region of boundary-layer separation extended over the aft 7% of flap chord. The airfoil configuration was tested at a Mach number of 0.09 and a chord Reynolds number of 1.8 × 106 in the NASA Ames Research Center 7- by 10-Foot Wind Tunnel. The flow was complicated by the presence of a strong, initially inviscid, jet, emanating from the slot between airfoil and flap, and a gradual merging of the main airfoil wake and flap suction-side boundary layer.Research Engineer, NRC Research AssociateAerospace Engineer 相似文献
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基于可拓学理论的围岩分级方法在变质软岩隧道中的应用 总被引：2，自引：0，他引：2
对可拓学中物元、可拓集合的概念进行了阐述,并以火车岭隧道为例,结合影响变质软岩区隧道稳定性的岩性、结构面、地下水等主要因素,选取钻孔岩芯质量、隧道埋深、地下水流量、饱和单轴抗压强度、结构面间距作为评价指标,同时选择3个典型岩段,建立相应的待评物元模型;对各评价指标及各围岩级别的关联度指标进行了计算,据此对3个岩段进行分级的结果表明,绿泥钠长石英片岩岩段为Ⅲ级,与原设计相符;绢云母石英片岩岩段为Ⅱ级,比原设计低一级;白云钠长石英片岩岩段为Ⅳ级,比原设计高一级.该分级方法与RMR法、Q法及公路隧道规范分级方法的对比结果表明,传统方法与现场条件存在较大误差,证明基于可拓学理论的围岩分级方法能较好地满足该围岩条件的要求,同时分析了传统围岩分级方法在该地质条件下应用的缺陷. 相似文献
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增强型地热系统(EGS)中高温岩石与流体之间的对流换热特征一直以来是干热岩(HDR)研究的重要基础内容。岩石导热热阻对裂隙对流换热特征具有重要影响。为研究其具体影响,综合运用理论解析与数值模拟2种研究方法,通过对解析解讨论以及建立数值模型,研究两平行光滑平板之间的换热规律。结果表明：流体速度、传热边界层充分发展时,局部努塞尔特准数Nux为定值,与其他因素无关;局部对流换热系数hx仅与流体热导率k和裂隙开度e有关,与其他因素无关。上下平板壁面热流恒定时,Nux为8.235;温度恒定时,Nux为7.54。然后建立多组导热热阻不同的岩石裂隙对流换热数值模型,发现岩石导热热阻增大,温度场进口段延长,对流换热系数h增大。岩石长度显著影响进口段占比,进而影响h的大小。h随着长度增大而减小;当岩石长度足够长时,进口段占比足够小,此时除k与e之外的参数对h基本没影响。并且发现实验室常用岩石长度为100 mm,而典型EGS工程中裂隙长度是米级的,建议室内实验重视岩石长度对裂隙对流换热特征的影响。 相似文献
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《地学前缘(英文版)》2016,7(1)
Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accuracy of estimating the bearing capacity of rock beneath them. Several traditional numerical approaches are proposed for the estimation of the bearing capacity of foundations resting on rock masses to avoid performing elaborate and expensive experimental studies. Despite this fact, there still exists a serious need to develop more robust predictive models. This paper proposes new nonlinear prediction models for the ultimate bearing capacity of shallow foundations resting on non-fractured rock masses using a novel evolutionary computational approach, called linear genetic programming. A comprehensive set of rock socket, centrifuge rock socket, plate load and large-scaled footing load test results is used to develop the models. In order to verify the validity of the models, the sensitivity analysis is conducted and discussed. The results indicate that the proposed models accurately characterize the bearing capacity of shallow foundations. The correlation coefficients between the experimental and predicted bearing capacity values are equal to 0.95 and 0.96 for the best LGP models. Moreover, the derived models reach a notably better prediction performance than the traditional equations. 相似文献
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大断面浅埋黄土隧道锚杆作用效果的试验研究 总被引：9，自引：1，他引：8
黄土隧道系统锚杆的作用效果问题一直是争论的焦点。结合正在修建的郑州-西安铁路客运专线大断面黄土隧道,采用现场对比试验方法对系统锚杆作用效果进行研究。为了使试验结果有可比性,选取试验条件基本相同的贺家庄隧道洞身段作为试验段,分别设置有系统锚杆段40 m和无系统锚杆段40 m。对比试验的内容包括：拱顶下沉、拱脚下沉、水平收敛、围岩压力、初支钢架应力、锚杆轴力等。试验结果表明,有系统锚杆段比无系统锚杆段的拱顶沉降大40 %左右、水平收敛大25 %左右,两者的土压力和钢架应力相差不大;锚杆轴力较小,且拱部受压。经综合分析认为,拱部锚杆的支护效果不明显,取消拱部锚杆可减少施工工序,加快隧道初期支护断面及早封闭,能更好地控制支护沉降与变形,并节约工程投资。 相似文献
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The exit section of Duck River Tunnel owns characteristics of bedding geology and unsymmetrical loading terrain. A centrifugal model test concerning the destruction process of Duck River Tunnel is conducted. Test results are concluded as follows: The surrounding rock at the bottom of the right sidewall is the first to be destroyed; the fracture planes in surrounding rock on both left and right side lead to the ground surface; the rupture angles are different from homogenous rock mass. Results of numerical model are consistent with the test results. For doing some comparative study, numerical models of homogeneous and bedding rock mass are respectively established. Conclusions are summarized from numerical analysis as follows: The stress distribution law of bedding surrounding rock is basically similar with that of homogeneous surrounding rock, while the stress value of bedding surrounding rock is larger than that of homogeneous rock. Meanwhile, the surrounding rock stress of the structural plane increases or decreases by leaps and bounds, and the stress intensity at the bottom of right sidewall is the highest as well as the surrounding rock, there is also the most easily destructible, which is the same as the test result. The research results have significant reference value to similar projects. 相似文献
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岩爆是在高地应力区域中进行地下隧道建设时所面对的主要风险之一,具有突发性、高危害性等特点。实现岩爆的破坏程度定量化预测,对高地应力区域地下工程的设计与施工具有重要的指导意义。本文通过收集大量国内外典型岩爆隧道的特征参数并进行统计分析,建立了一种能够预测最大爆坑深度的岩爆风险量化预测模型,同时结合室内力学试验、岩体强度损伤准则和地应力场多元线性回归反演等理论和方法,对新建某交通线路色季拉山隧道岩爆风险进行了定量化预测,并与国内巴玉隧道岩爆风险进行相似工程案例对比分析。得出以下结论:(1)本文根据岩爆隧道应力强度比与爆坑深度之间线性统计关系所建立的岩爆预测模型,可实现岩爆风险的量化预测及评估。(2)色季拉山隧道地应力场受构造作用控制明显,同时,全线地应力普遍较高,加之隧道沿线硬岩段落占比大且岩爆倾向性高,高地应力岩爆风险突出。(3)预测色季拉山隧道中等以上等级岩爆风险段落可达12 188 m,占隧道全长的32.1%,岩爆将主要发生在弱风化花岗岩、闪长岩以及埋深较大的片麻岩段落中。(4)色季拉山隧道预测最大爆坑深度为3.42 m,小于已贯通的巴玉隧道实测最大爆坑深度(3.5 m),在合理的防控措施下可认为色季拉山隧道的岩爆风险总体可控。 相似文献
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位于长江南岸堤圩区某变电所综合楼地基上部为厚层淤泥土，设计采用静压钢筋泥凝土预制桩。试桩的基桩静载荷试验全部满足设计要求，而工程桩静压载荷试验有50%的基桩承载力达不到设计要求。分析了场地的工程地质条件、影响桩静载荷试验承载力的施工因素、群桩的时间效应和群桩的挤土效应等，有针对性地进行了处理，满足了工程设计要求。 相似文献
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城市陆面过程与边界层结构研究 总被引：6，自引：1，他引：5
通过城市边界层观测、卫星遥感以及城市边界层数值模拟等途径,获取对城市陆面过程特性的认识,研究建立精细城市边界层模式,引入合理城市区陆面过程参数化方案,并进行城市边界层结构影响研究。研究结果表明：①城市下垫面能量平衡过程迥异于自然地表,引入合理的参数化方案是改善数值模拟性能的关键。②高分辨卫星观测信息是认识城市地表参数状况及其变化的有效途径。 ③人为热排放参数化方案的合理引入是准确描述地表能量平衡过程的又一重要课题。需根据实际情况确定人为热排放的引入方案及量值变化。④应从合理描述城市建筑物下垫面对热力输送及大气动力场的影响出发,研究建立了多层城市冠层模式。⑤应建立更完善的多尺度城市边界层模式系统并引入更新的城市效应参数化方案和数据同化处理,以增强并完善城市边界层数值模拟能力。 相似文献
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土钉墙空间效应和平滑破坏模式的三维分析 总被引：5，自引：2，他引：5
在实际工程中,土钉墙稳定性评估一般采用转动破坏模式,且不考虑其空间效应对设计方案的影响,其结果是有时得到的结论与实际状况不相符合.本文采用三维极限分析方法,对土钉墙空间效应和平滑破坏两个方面的问题进行了讨论,并结合一实际工程,对它们进行了分析,得到一些初步结论,以期对实际工程有一定的参考价值. 相似文献
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This paper first analyzes the factors influencing the safe thickness and the broken mechanism of rock between a tunnel and the surrounding concealed caves on the Cheng-gui railway line. Then, based on the analysis of broken mechanism, a comprehensive numerical analysis method, which is based on the Yujingshan Tunnel project, is put forward. This method of analysis is simulated using FLAC3D software to perform three-dimensional numerical simulations for different positions, providing the basis for the subsequent safe thickness analysis and construction scheme design. Actual monitoring and computational results shows the safety distance of the range of the tunnel’s diameter, which proved the rationality and effectiveness of the calculation of the safe thickness between the tunnel and the surrounding concealed caves. 相似文献
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Wind‐blown sand movement, considered as a particle‐laden two‐phase flow, was simulated by a new numerical code developed in the present study. The discrete element method was employed to model the contact force between sand particles. Large eddy simulation was used to solve the turbulent atmospheric boundary layer. Motions of sand particles were traced in the Lagrangian frame. Within the near‐surface region of the atmospheric boundary layer, interparticle collisions will significantly alter the velocity of sand. The sand phase is quite dense in this region, and its feedback force on fluid motion cannot be ignored. By considering the interparticle collision and two‐phase interaction, four‐way coupling was achieved in the numerical code. Profiles of sand velocity from the simulations were in good agreement with experimental measurements. The mass flux shows an exponential decay and is comparable to reported experimental and field measurements. The turbulence intensities and shear stress of sand particles were estimated from particle root‐mean‐square velocities. Distributions of slip velocity and feedback force were analysed to reveal the interactions between sand particles and the continuous fluid phase. 相似文献
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CAI Hou＇an LIANG Handong ZHANG Jun LUO Chunping 《《地质学报》英文版》2006,80(1):46-51
The Meishan section of China has been confirmed as the ＂Global Stratotype Section and Point＂ of the P/T boundary. In the section, the authors found several types of iron grains, including pyrite, pure iron grains and goethite. From the research of macro minerals, it is easy to find that the grains rich in iron appear from the bottom of the event layer of the section. In other words, it is probably residue of the geochemical catastrophe of that time. Therefore, it is important to trace the source of these iron grains and their relationships, which probably provides evidence for volcanic eruption or impact-volcanoes and has directive significance to the crisis during the P/T transitional period. Through the study of the characterization and relationships of these iron grains, the authors make a preliminary discussion on the P/T mass extinction. 相似文献
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高寒隧道保温结构的优化设计研究
——以西藏圭嘎拉隧道为例 总被引：1，自引：1，他引：0
为了提高季节冻土隧道的防冻保温性能,常采用铺设聚氨酯类有机保温层的方式以防止围岩冻结,但由于有机材料在冻融循环过程中老化速度快、保温结构设计缺少科学依据等局限性,使得部分隧道在长期运营过程中反复出现冻融病害。以西藏圭嘎拉隧道为研究对象,通过建立热流固耦合计算模型,对现行保温措施的防冻效果进行分析,发现距离洞口一定长度范围内的围岩仍会发生冻融破坏。在隧道运营后第20年2月15日,距洞口5 m处断面拱顶围岩的边界温度仅为-0.91 ℃,并且该关键位置的纵向冻结长度超过500 m,严重影响隧道结构的安全。为防止此隧道出现冻害问题,提高其服役能力,拟采用新型无机建筑材料气凝胶毡对隧道的保温结构进行加固,其具有良好的保温、阻燃和耐久性能,并且铺装简便、易于操作。此外通过对不同厚度气凝胶毡条件下的围岩温度场进行多维度分析,确定了最不利时刻气凝胶毡厚度与拱顶围岩关键位置纵向冻结长度之间的关系。研究成果可为圭嘎拉隧道防冻保温优化设计提供技术支持,不仅能保障隧道结构的安全性和稳定性,也能为季节冻土隧道保温结构的设计、施工及维护提供参考依据。 相似文献