共查询到18条相似文献,搜索用时 265 毫秒
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应用ANSYS软件对在通风量不同情况下围岩调热圈温度分布及井巷在自然通风状态下与人工通风情况下各自围岩调热圈温度分布情况进行数值模拟。结果表明在自然通风情况下调热圈半径为3.09 m,人工通风作用下调热圈向岩层内部扩散较为显著,且其值为4.3 m。对高温深井进行通风量控制以及热害防治有指导意义。 相似文献
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随着地下工程不断向地层深部发展,高地温对工程影响日益显著,为了保证引水隧洞的稳定和运行安全,利用室内仿真试验装置模拟高地温隧洞内的湿热环境,测试高温环境下混凝土与围岩粘结强度,并通过试验获得粘结强度与温度的关系分析了孔隙率和破坏面的位置。研究结果表明,温度对粘结强度的影响较大,与标准工况20℃相比,70℃工况下粘结强度较低且降幅达15.28%;20℃工况下混凝土致密性较好,70℃工况下孔隙率较大,但整体结构稀疏多孔且高温环境下粘结破坏断面多位于交界面混凝土1mm位置。 相似文献
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高温病害问题尤为突出,成为长大深埋越岭隧道建设过程中常见的技术难点。因此,以建(个)元高速尼格隧道为工程依托,基于现场监测数据,探明洞内气温和围岩温度场演变规律,分析隧道支护结构在高地温环境下的力学特性和安全特性。研究结果表明:(1)洞内气温时态曲线具有稳定和降温阶段,围岩温度则经历自然衰减期—稳定期—降温期;(2)洞内气温由出口至进口沿隧洞纵向呈缓慢升温—迅速降温变化,岩温随深度增加以抛物线形式增加;(3)基于混凝土应变计监测数据,验算二次衬砌安全性,计算结果合理准确,二次衬砌稳定且具有良好的安全储备,高地温控制理念正确,控制方法合理。 相似文献
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二次衬砌结构刚度与施作时机优选是隧洞工程中关键问题之一,对于引水隧洞穿越软弱流变围岩洞段则尤为突出。为研究引水隧洞开挖过程中时空效应耦合作用对二衬优选的影响,基于现场围岩和支护结构实测应力变形数据,采用三维粘弹塑性有限元方法,结合开挖和支护设计实际工况考虑二次衬砌施作距掌子面不同距离和不同二衬刚度(厚度),分析了围岩变形、二衬内力及变形的变化规律。结果表明,二衬刚度对二衬时机的优选影响不大,围岩应力的释放及围岩变形为二衬时机优选的关键因素,最后针对设计和施工人员开发了二衬支护结构优选系统。研究成果和优选系统可为类似隧洞工程施工和设计提供参考依据。 相似文献
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以引江济淮工程派河口泵站为例,采用ANSYS有限元软件模拟分析了大型泵站混凝土墩墙内部布置HDPE冷凝管后温度场,对照现场无线测温数据验证模拟结果的准确性,并通过对比墩墙内有、无冷凝水管两种情况下的实测温度数据,分析了冷凝水管对混凝土内部温度场的影响。研究结果表明,采用在墩墙内部设置冷凝水管的方式能够有效降低结构内部温度,减小里表温差;采用HDPE能有效减缓混凝土降温速率;冷凝水管间距应根据数值模拟结果进行初步确定,并利用现场测温仪进行校验,及时调整冷凝管布置间距,以达到更好的降温效果。 相似文献
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肖作文 《电网与水力发电进展》2003,19(4):51-54
碾压混凝土夏季高温施工是其施工难题之首,本文从调整施工配合比、降低混凝土的入仓温度和对仓面进行喷雾降温保湿等仓面控制措施三个方面,论述了山口电站夏季高温RCC施工采取的施工技术措施。 相似文献
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为了更好地了解围岩与衬砌之间的相互作用,利用三维拉格朗日有限差分法,在商业软件FLAC3D中通过设定接触面来研究不同工况下围岩与衬砌间的接触状态及围岩与衬砌的应力、应变规律。通过数值模拟破坏性试验揭示高应力下待开挖区域变形规律,通过接触面来反映隧洞围岩和衬砌嵌入形态。模拟结果表明,岩性和开挖支护方式选择在实际地下隧洞施工中起着重要作用。 相似文献
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鉴于地下水丰富且地质条件复杂洞段采用超前灌浆技术是解决涌水突砂和加固围岩效果较好的工程措施。选取滇中引水隧洞高埋深、高水头、Ⅳ类围岩段为例,采用数值分析的方法探讨了超前灌浆深度的合理化选取,并对比分析了有无超前灌浆下洞周围岩的加固和防渗效果。结果表明,与无超前灌浆相比,在合理的灌浆深度下洞周围岩的变形量和破坏深度及隧洞的渗水量均明显减小,超前灌浆达到了加固围岩和防渗的双重效果,为实际施工中遇到类似问题提供了切实可行的建议。 相似文献
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隧道围岩稳定性评价的改进熵权-属性识别模型 总被引:1,自引:0,他引:1
以石牌岭隧道围岩工程为例,参照国内外研究现状,选取6个主要影响因素作为评价指标,将岩体质量等级分为5级,采用Zscores标准对传统熵权加以修正并应用到模型中,保证了评价的客观性和准确性。通过构建隧道岩体质量评价属性决策矩阵,再由级别特征值来确定所属级别,进而对隧道围岩稳定性作出评价。该模型不仅能预测围岩等级,还能对同等级围岩的稳定性进行排序,通过与可拓法评价结果的比较分析,验证了该方法的合理性与优越性,为隧道围岩稳定性评价提供了新的思路。 相似文献
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Natural night ventilation is an interesting passive cooling method in moderate climates. Driven by wind and stack generated pressures, it cools down the exposed building structure at night, in which the heat of the previous day is accumulated. The performance of natural night ventilation highly depends on the external weather conditions and especially on the outdoor temperature. An increase of this outdoor temperature is noticed over the last century and the IPCC predicts an additional rise to the end of this century. A methodology is needed to evaluate the reliable operation of the indoor climate of buildings in case of warmer and uncertain summer conditions. The uncertainty on the climate and on other design data can be very important in the decision process of a building project.The aim of this research is to develop a methodology to predict the performance of natural night ventilation using building energy simulation taking into account the uncertainties in the input. The performance evaluation of natural night ventilation is based on uncertainty and sensitivity analysis.The results of the uncertainty analysis showed that thermal comfort in a single office cooled with single-sided night ventilation had the largest uncertainty. The uncertainties on thermal comfort in case of passive stack and cross ventilation were substantially smaller. However, since wind, as the main driving force for cross ventilation, is highly variable, the cross ventilation strategy required larger louvre areas than the stack ventilation strategy to achieve a similar performance. The differences in uncertainty between the orientations were small.Sensitivity analysis was used to determine the most dominant set of input parameters causing the uncertainty on thermal comfort. The internal heat gains, solar heat gain coefficient of the sunblinds, internal convective heat transfer coefficient, thermophysical properties related to thermal mass, set-point temperatures controlling the natural night ventilation, the discharge coefficient Cd of the night ventilation opening and the wind pressure coefficients Cp were identified to have the largest impact on the uncertainty of thermal comfort.The impact of the warming climate on the uncertainty of thermal comfort was determined. The uncertainty on thermal comfort appeared to increase significantly when a weather data set with recurrence time of 10 years (warm weather) was applied in the transient simulations in stead of a standard weather data set. Natural night ventilation, designed for normal weather conditions, was clearly not able to ensure a high probability of good thermal comfort in warm weather. To ensure a high probability of good thermal comfort and to reduce the performance uncertainty in a warming climate, natural night ventilation has to be combined with additional measures. Different measures were analysed, based on the results of the sensitivity analysis. All the measures were shown to significantly decrease the uncertainty of thermal comfort in warm weather. The study showed the importance to carry out simulations with a warm weather data set together with the analysis under typical conditions. This approach allows to gain a better understanding of the performance of a natural night ventilation design, and to optimize the design to a robust solution. 相似文献
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基于RS-可拓云模型的水工隧洞围岩安全评价 总被引:1,自引:0,他引:1
为了提高水工隧洞施工安全评价结果的可靠性,选取岩石质量指标、湿抗压强度、完整性系数、结构面强度系数、地下水渗水量5个因素作为评价指标,运用改进重要度的粗糙集计算客观权重,选取可拓云模型充分考虑以往围岩评价过程中由于等级分界与数据获取存在的不确定性,构建了基于RS(粗糙集)-可拓云模型的水工隧洞围岩安全评价方法,并将该方法应用于某水工隧洞中的12段围岩中。结果表明,改进重要度的粗糙集计算的权重,既能满足所得权重的客观性,也能保证评估结果具有一定的解释性,基于RS-可拓云模型对于水工隧洞围岩安全等级的确定较为有效,通过该方法得出的隧洞围岩安全等级与实际情况一致。研究成果为水工隧洞围岩安全评价提供了一定的参考。 相似文献
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Mohamed B. Gadi 《Applied Energy》2000,65(1-4):355-366
This paper presents the results of simulating the ventilation and thermal performance of a new passive cooling and heating system. The new system was integrated into the roof of a typical contemporary North African house, which was modelled and mounted inside a wind tunnel, for natural ventilation simulation. Thermal performance of the new system was simulated using a new computer programme (BTS), developed by the author. Results are presented in terms of indoor temperature and CATD and HATD, which are newly introduced concepts in defining the building cooling and heating loads. 相似文献