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81.
研究目的:铁道部1997年引进的两台TB880E型TBM由德国Wirth公司生产,该机型的结构及技术性能参数以西安安康铁路秦岭特长隧道为设计对象,主要适用于硬岩隧道的掘进施工,属敞开式硬岩TBM。TBM如何通过软弱围岩是一个世界性的难题。研究方法:结合西安南京铁路桃花铺1号隧道的工程实践,研究预防TBM施工事故的措施和施工方法。研究结论:提出了“超前探测,支护紧跟,调整参数,适速推进,减少扰动”20字方针。对于施工过程中出现的各种坍方如何处理进行了说明,总的处理措施是“及时喷锚,加密钢架,搭焊钢管,网板结合,封闭坍腔,回填密实”。TBM顺利、安全通过不良地质地段的措施和方法在桃花铺1号隧道的掘进后期得到很好的验证。 相似文献
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83.
Road vehicle detection and, to a lesser extent, classification have received considerable attention, in particular for the purpose of traffic monitoring by transportation authorities. A multitude of sensors and systems have been developed to assist people in traffic monitoring. Camera-based systems have enjoyed wide adoption over the last decade, partially substituting for more traditional techniques. Methods based on road-pavement vibration are not as common as camera-based systems. However, vibration sensors may be of interest when sensors must be out of sight and insensitive to environmental conditions, such as fog. We present and discuss our work on detection and classification of vehicles by measurement of road-pavement vibration and by means of supervised machine learning. We describe the entire processing chain from sensor data acquisition to vehicle classification and discuss our results for the task of vehicle detection and the task of vehicle classification separately. Using data for a single vibration sensor, our results show a performance ranging between 94% and near 100% for the detection task (1340 samples) and between 43% and 86% for the classification task (experiment specific, between 454 and 1243 samples). 相似文献
84.
URANS analysis of a broaching event in irregular quartering seas 总被引:1,自引:0,他引:1
Pablo M. Carrica Kwang-Jun Paik Hamid S. Hosseini Frederick Stern 《Journal of Marine Science and Technology》2008,13(4):395-407
Ship motions in a high sea state can have adverse effects on controllability, cause loss of stability, and ultimately compromise
the survivability of the ship. In a broaching event, the ship losses control, naturally turning broadside to the waves, causing
a dangerous situation and possibly capsizing. Classical approaches to study broaching rely on costly experimental programs
and/or time-domain potential or system-based simulation codes. In this paper the ability of Reynolds averaged Navier–Stokes
(RANS) to simulate a broaching event in irregular waves is demonstrated, and the extensive information available is used to
analyze the broaching process. The demonstration nature of this paper is stressed, as opposed to a validated study. Unsteady
RANS (URANS) provides a model based on first principles to capture phenomena such as coupling between sway, yaw, and roll,
roll damping, effects of complex waves on righting arm, rudders partially out of the water, etc. The computational fluid dynamics
(CFD) method uses a single-phase level-set approach to model the free surface, and dynamic overset grids to resolve large-amplitude
motions. Before evaluating irregular seas two regular wave cases are demonstrated, one causing broaching and one causing stable
surf riding. A sea state 8 is imposed following an irregular Bretschneider spectrum, and an autopilot was implemented to control
heading and speed with two different gains for the heading controller. It is concluded that the autopilot causes the ship
to be in an adverse dynamic condition at the beginning of the broaching process, and thus is partially responsible for the
occurrence of the broaching event. 相似文献
85.
Naoya Umeda Hirotada Hashimoto Akihiko Matsuda 《Journal of Marine Science and Technology》2003,7(3):145-155
We have attempted to develop a more consistent mathematical model for capsizing associated with surf-riding in following
and quartering waves by taking most of the second-order terms of the waves into account. The wave effects on the hull maneuvring
coefficients were estimated, together with the hydrodynamic lift due to wave fluid velocity, and the change in added mass
due to relative wave elevations. The wave effects on the hydrodynamic derivatives with respect to rudder angles were estimated
by using the Mathematical Modelling Group (MMG) model. Then captive ship model experiments were conducted, and these showed
reasonably good agreements between the experiments and the calculations for the wave effects on the hull and the rudder maneuvring
forces. It was also found that the wave effects on restoring moments are much smaller than the Froude–Krylov prediction, and
the minimum restoring arm appears on a wave downslope but not on a wave crest amidship. Thus, an experimental formula of the
lift force due to the heel angle of the ship is provided for numerical modelling. Numerical simulations were then carried
out with these second-order terms of waves, and the results were compared with the results of free-running model experiments.
An improved prediction accuracy for ship motions in following and quartering seas was demonstrated. Although the boundaries
of the ship motion modes were also obtained with both the original model and the present one, the second-order terms for waves
are not so crucial for predicting the capsizing boundaries themselves.
Received: June 20, 2002 / Accepted: October 10, 2002
Acknowledgments. This research was supported by a Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science
and Technology of Japan (No. 13555270). The authors thank Prof. N. Rakhmanin of the Krylov Ship Research Institute for providing
the Russian literature, as well as Mr. H. Murata of NHK (Japan Broadcasting Corporation) for translating it into Japanese.
Address correspondence to: N. Umeda (e-mail: umeda@naoe.eng.osaka-u.ac.jp) 相似文献
86.
87.
简述了接触线滑板磨耗机的基本结构和工作原理。选用西门子S7-200PLC作为主控制器.用于完成对整个试验过程的顺序控制。同时该系统使用了变频器、旋转编码器和触摸屏等现代工业设备。较之原系统,设备性能有了很大提高。 相似文献
88.
机制砂混凝土在工程实践中的应用 总被引:1,自引:0,他引:1
庞林太 《铁路工程造价管理》2007,22(4):28-31,59
针对天然砂资源逐步减少,质量日益下降,难以满足建筑用砂持续发展这一现实情况,论述机制砂的优缺点和机制砂混凝土的研究现状,从机制砂混凝土的工作性能、力学性能、耐久性能等方面阐述机制砂对混凝土性能的影响。在工程实践中,应用机制砂配制出的C10~C55混凝土,已在水利、铁路、公路工程中成功应用。目前,机制砂混凝土在我国的应用尚处于起步阶段,推行与应用还需要对机制砂的颗粒形状、颗粒级配,高效、优质制砂设备和制砂工艺,混凝土配合比等课题进行深入探讨。 相似文献
89.
孟炜 《筑路机械与施工机械化》1993,10(2):35-38
本文从水泥路面的重要性出发,介绍了水泥路面施工工艺流程与机械化施工成套设备的初步规划,提出了配套与配合机械产品开发设想,并就其市场需求与产品社会、经济效益进行了初步分析。 相似文献
90.