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为了达到快速、准确、可靠的围岩分类,有效指导隧道施工,在充分研究和吸取国内外有关围岩分类的经验和成果基础上,针对隧道施工期间的围岩类别鉴定方法,提出了一种可用于隧道施工期间围岩类别鉴定的快速分类方法,该方法以定量与定性相结合、多专家评分的方式在开挖掌子面现场进行观察、量测及评价,无需复杂试验或测量以及繁杂计算,可迅速得出评价结果。为了更加全面地反映隧道围岩情况,准确评价围岩工程性质,结合目前国际上流行的Q分类系统,在富溪隧道第一手实测资料的基础上,根据快速分类结果和Q指标分类结果对富溪隧道围岩条件进行综合评价,为其隧道施工提供了合理的支护参数。 相似文献
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钎焊过程中在焊锡接点中形成的金属间化合物(IMC)对焊锡接点可靠性具有重要影响.在原子扩散效应下,回流焊和等温时效过程中IMC层的生长会在其内部产生应力,其微结构也发生变化,致使IMC层和整个焊锡接点的力学性能下降.论文基于扩散反应机制,研究了由于原子扩散产生的IMC层的扩散应力.首先建立了描述焊锡接点IMC层生长早期微结构特征的2界面(Cu/Cu6 Sn5/Solder)分析模型,然后运用Laplace变换法求解扩散方程得到了Cu原了在IMC层中的浓度分布;采用把原子扩散作用转换为体应变方法,计算了IMC层在形成和生长过程中应力的解析解.结果表明:IMC层中的扩散应力为压应力,最大值位于Cu/IMC界面处,大小与扩散原子浓度密切相关;随着时效时间的增加,扩散应力增大,但最终趋于稳定并沿IMC厚度方向线性变化. 相似文献
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滑坡地段隧道变形机理的模型试验研究 总被引:3,自引:0,他引:3
通过室内地质力学模型试验,研究了滑坡地段坡体变形与隧道的相互作用机理、围岩和衬砌压力的变化规律以及坡体和隧道的变形特征,着重研究了滑带土浸水软化及发生蠕变时坡体变形与隧道的相互作用关系。本文的成果可为该类病害的预测预报和有效整治提供科学依据。 相似文献
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A computational study has been carried out to examine the effects of driver gas contamination in the NASA HYPULSE facility at GASL when operating with a detonation driver in reflected-shock tunnel mode. Unlike high-enthalpy shock tunnels which use helium as a driver gas, the driver gas in a detonation driver consists of a mixture of water vapour and argon, which has very different chemical and thermodynamic properties than those of helium. The purpose of the present work is to quantitatively evaluate the effects of driver gas contamination on the flow properties in the test section. Two computational analyses have been performed. The first analysis examined the nozzle flow under the influence of a prescribed level of driver gas contamination. In the second analysis, the transient development of the driver gas leakage in the reflected-shock region in the shock tube is studied. The unique flow features brought about by the detonation-driver gas and the method for detecting the contamination are discussed.Received: 6 August 2002, Revised: 22 September 2003, Published online: 10 February 2004Correspondence to: R.S.M. ChueAn abridged version of this paper was presented at the 23rd International Symposium on Shock Waves at Fort Worth, Texas, July 23 to 27, 2001 相似文献
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G. G. Tsypkin 《Fluid Dynamics》2005,40(1):117-125
The problem of gas recovery in the process of methane hydrate dissociation in a reservoir saturated with gas-hydrate mixture is considered. The mathematical model of hydrate decomposition into gas and water is generalized to include the negative temperature interval and takes ice formation into account. The solution of the problem is represented in the self-similar approximation. It is shown that there exists a transition hydrate decomposition regime in which water and ice are formed simultaneously. A comparative analysis of the recovery is carried out on the basis of relations derived for the masses of recovered gas in different hydrate dissociation regimes. It is shown that an anomalous increase in the recovered gas volumes is observed in the transition hydrate dissociation regime.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, 2005, pp. 132–142. Original Russian Text Copyright © 2005 by Tsypkin. 相似文献
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V. V. Shumskii M. I. Yaroslavtsev 《Journal of Applied Mechanics and Technical Physics》2005,46(1):21-32
Gas dynamics of a low-pressure chamber in a double-chamber hotshot wind tunnel is considered. The time needed to fill the second chamber is in good agreement with the value obtained by examining the quasi-steady process of emptying and filling of the high-pressure and low-pressure chambers. The transitional process is strongly affected by wave processes in the channel between the chambers. By changing the place of the throttling grid in this channel, one can change the time of filling of the second chamber (decrease it severalfold). The examined schemes of air input into the second chamber ensure its complete deceleration. The Mach number at the exit of the second chamber (in the wind-tunnel nozzle throat) is almost constant over the cross section and close to unity.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 1, pp. 29–43, January–February, 2005. 相似文献
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Simulations of a complete reflected shock tunnel facility have been performed with the aim of providing a better understanding of the flow through these facilities. In particular, the analysis is focused on the premature contamination of the test flow with the driver gas. The axisymmetric simulations model the full geometry of the shock tunnel and incorporate an iris-based model of the primary diaphragm rupture mechanics, an ideal secondary diaphragm and account for turbulence in the shock tube boundary layer with the Baldwin-Lomax eddy viscosity model. Two operating conditions were examined: one resulting in an over-tailored mode of operation and the other resulting in approximately tailored operation. The accuracy of the simulations is assessed through comparison with experimental measurements of static pressure, pitot pressure and stagnation temperature. It is shown that the widely-accepted driver gas contamination mechanism in which driver gas ‘jets’ along the walls through action of the bifurcated foot of the reflected shock, does not directly transport the driver gas to the nozzle at these conditions. Instead, driver gas laden vortices are generated by the bifurcated reflected shock. These vortices prevent jetting of the driver gas along the walls and convect driver gas away from the shock tube wall and downstream into the nozzle. Additional vorticity generated by the interaction of the reflected shock and the contact surface enhances the process in the over-tailored case. However, the basic mechanism appears to operate in a similar way for both the over-tailored and the approximately tailored conditions.Communicated by R. R. Boyce 相似文献
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EXPERIMENTAL INVESTIGATIONS ON DIFFUSION CHARACTERISTICS OF HIGH CONCENTRATION JETS IN ENVIRONMENTAL CURRENTS 总被引:5,自引:1,他引:5
IntroductionJetreferstoamovingliquidstreamshotordrivenbymachineryfromanexitintoambientwaterbody .Iftheinitialdensityofthejetisn’tthesameasthatoftheambientfluid ,thejetwillmixwiththeambientwaterbodyanditsdensitywillchange.Whentwo (ormorethantwo)kindsofflu… 相似文献
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液体火箭爆炸地面有害气体生成与扩散分析 总被引:1,自引:0,他引:1
建立了自燃液体推进剂运载火箭爆炸时地面残余推进剂蒸发模型和产生的有害气体在大气中的扩散模型,给出了N2O4/UDMH液体推进剂爆炸产生的地面推进剂残留量、推进剂污染区直径、大气环境中地面残余N2O4和UDMH推进剂蒸发速率等参数的实验结果。利用该理论模型对大型运载火箭发生意外爆炸事故产生的地面残余推进剂蒸发时间和形成的有害气体危害范围进行了估算。该理论模型可为航天发射场制定安全防护措施提供有用的评估方法。 相似文献
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We study the boundary-layer approximation of the classical mathematical model that describes the discharge of a laminar hot
gas in a stagnant colder atmosphere of the same gas. We prove the existence and uniqueness of solutions to a nondegenerate
problem (without zones of stagnation of gas temperature or velocity). The asymptotic behavior of these solutions is also studied
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 4, pp. 192–205, July–August, 2008. 相似文献
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针对隧道爆破施工中采集到的实测振动信号,引入一种基于总体平均经验模态分解方法(CEEMDAN分解)联合小波包分析的降噪方法。首先,通过CEEMDAN分解得到多个本征模态分量,利用相关系数筛选出包含噪声的模态分量,并通过模态分量的频谱图及方差贡献率进行校核。然后,利用小波包阈值降噪方法对含有噪声的模态分量进行处理。最后,将未经处理的模态分量与去噪完成的分量重构得到最终纯净的爆破振动信号。同时,通过小波包能量谱分析验证此降噪方法的可行性。本文引入的方法兼具CEEMDAN分解及小波包分析的优点,与现有方法相比,去噪效果较好,可以应用于类似隧道爆破信号的去噪处理中。 相似文献
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气体化学反应流动的DSMC/EPSM混合算法研究 总被引:3,自引:0,他引:3
发展了平衡粒子模拟方法(EPSM),建立了与高温气体化学反应动力学理论相匹配的:EPSM耦合模型,并通过混合参数进行流区的自动识别,将:EPSM方法与蒙特卡罗直接模拟方法(OSMC)结合,构造了可模拟化学反应流动的DSMC/EPSM混合算法。应用该算法对汲及化学反应的二维高超音速竖板绕流流场进行模拟,将结果与DSMC方法的结果进行比较,验证了新算法对求解化学反应流动的可行性。将混合算法的计算效率与DSMC方法的计算效率进行比较,发现混合算法能够大大提高计算效率。 相似文献