共查询到19条相似文献,搜索用时 375 毫秒
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为分析凿岩机的破岩过程,提高其破岩效率,采用离散单元法分析软件PFC3D探究凿岩机钻头的破岩过程。通过模拟在不同加载速率下单钻头凿岩机的破岩过程,并以破岩比功表征两种风化程度花岗岩的破碎程度,探讨了相应的凿岩机破岩效率;进一步分析不同条件下破岩比功的变化规律,得出了有效提高凿岩机破岩效率的最佳参数选择。 相似文献
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将前混合磨料水射流破岩技术应用于硬岩掘进机(TBM)上,有望解决隧道施工过程中遇到高强度岩石时,传统滚刀破岩效率低、成本高的难题,但前混合磨料水射流破岩受多种因素影响,系统复杂,在TBM破岩掘进领域的应用还不够成熟。基于此,利用高压水、砂破岩试验装置,开展了固定状态下喷头定时、移动状态下喷头定速的对比试验,研究不同静水压、射距、喷嘴的运动状态对磨料平均消耗量以及破岩坑槽深度和宽度的影响,针对破岩宽度效果,各因素影响大小依次为移动状态、射距、静水压;针对破岩深度,各因素影响大小依次为移动状态、静水压、射距。通过探究前混合磨料水射流技术的破岩最佳参数,为TBM的新型破岩技术研究提供依据。 相似文献
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文章介绍了地震波反射法、高密度电法(三电极法)和超前钻孔法三种探测技术的原理及现场测试,并对广乐高速公路长基岭隧道应用这三种探测手段进行的综合超前地质预报结果进行了分析研究。结果表明,间接预报和直接预报综合技术有一定的实用性;另外,单一预报方法都有一定的局限性,而综合地质预报方法能够实现优缺点互补,大大提升预报的针对性和可靠性。 相似文献
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我国地域广阔,自然地质条件复杂多样,岩溶等不良地质会对高速公路建设带来严重影响。高密度电法在勘察中的应用相比于普通钻探具有成本低、效率高、探测效果明显等特点。为查明清花高速公路连珠枢纽互通匝道的岩溶发育情况,本文采用了高密度电法进行物理探测,并结合钻探进行验证,能较好地探明地下岩溶的发育情况,应用效果较好。 相似文献
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Smart card data are increasingly used for transit network planning, passengers’ behaviour analysis and network demand forecasting. Public transport origin–destination (O–D) estimation is a significant product of processing smart card data. In recent years, various O–D estimation methods using the trip-chaining approach have attracted much attention from both researchers and practitioners. However, the validity of these estimation methods has not been extensively investigated. This is mainly because these datasets usually lack data about passengers’ alighting, as passengers are often required to tap their smart cards only when boarding a public transport service. Thus, this paper has two main objectives. First, the paper reports on the implementation and validation of the existing O–D estimation method using the unique smart card dataset of the South-East Queensland public transport network which includes data on both boarding stops and alighting stops. Second, the paper improves the O–D estimation algorithm and empirically examines these improvements, relying on this unique dataset. The evaluation of the last destination assumption of the trip-chaining method shows a significant negative impact on the matching results of the differences between actual boarding/alighting times and the public transport schedules. The proposed changes to the algorithm improve the average distance between the actual and estimated alighting stops, as this distance is reduced from 806 m using the original algorithm to 530 m after applying the suggested improvements. 相似文献
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After 1975, the appearance of finite element numerical limit method and the application and development of computer technology have brought the elastic-plastic analytical calculation of engineering materials into a new era of numerical limit calculation. The new methods, namely, strength reduction method and load increment method, as well as the recently proposed ultimate strain method, are adopted in the rock tunnels studied in this paper. To solve the uncertainty of mechanical parameters of surrounding rock in rock tunnels and provide more scientific and reasonable mechanical parameters of surrounding rock, the surrounding rock classification must be made combining theory, investigation and experience. Taking the surrounding rock classification in rail transit tunnels as an example, the improvement of the classification level includes improving the strength index, mainly adopting the quantitative classification method, reasonably determining the basic index BQ value of rock mass quality, increasing the number of surrounding rock classifications, formulating the surrounding rock classification tables for the running tunnel and the station tunnel, and achieving the coordination and unification of qualitative and quantitative classification methods. Finally, the quantitative indexes of surrounding rock self-stability are determined, and the more scientific and reasonable physical and mechanical parameters of surrounding rocks are put forward through back calculation. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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公路安全生命防护工程不仅是公路设计部门,也是公路养护管理部门重点考虑的内容,主要研究方向是以人民为中心,人性化设计、科学化管养。其中,护栏作为最常用的路侧安全生命防护工程,以经济可靠、防护性能好的优点得到广泛运用并在规范中不断完善。文章通过研究国内外护栏设计现状与近年安全事故数据,分析当今护栏设计中存在的不足,探究影响设计的主要因素,并介绍相关的评价方法。 相似文献
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公路隧道软弱围岩施工方法的探讨 总被引:1,自引:0,他引:1
文章根据当前软弱围岩中公路隧道的施工方法和施工特点,采用数值分析的方法,对台阶法、CD法、CRD法的施工力学特征和存在的问题进行了分析,并对各种施工方法进行了比较,提出了应用三种施工方法的建议。 相似文献
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船舶压载水处理方法综述 总被引:2,自引:1,他引:1
船舶压载水是船舶造成水污染的主要途径。船舶压载水含有的有害水生物主要有水藻、水母、斑马纹贻贝等。目前在航压载水常用的处理方法有的深海置换法、机械法、物理法、化学法。其中深海置换法包括排空法、溢流法和稀释法三种。 相似文献
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由于近年对承压设备安全及环境保护要求的不断提高,爆破片的性能和可靠性越来越受到人们的重视.作为产品质量考核的重要手段,型式试验被人们广泛采用和接受.在对爆破片型式试验方法、项目、装置的研究和试验过程中,对爆破片型式试验有了进一步的认识和理解. 相似文献