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喜河水电站右导墙紧临厂房基坑,基础围岩裂隙发育,深层抗滑稳定问题比较突出,倾向基坑的缓倾角断层的出露增加了基础边坡处理的难度。设计过程中根据枢纽布置和基础地质特性,分段建立计算模型,进行深层抗滑稳定性计算分析,并根据计算结果采取了相应的工程处理措施。 相似文献
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为分析水平力作用下框架码头桩侧向土压力的分布规律,通过土质岸坡框架码头模型试验,分析了一定水深条件下在水平推力作用下桩前后侧向土压力沿深度方向、水平方向的分布规律,探讨了框架码头土体岸坡潜在滑动面的位置。结果表明,各桩的桩后侧向土压力比桩前侧向土压力大;同一根桩上,随着距桩底距离的增加,侧向土压力呈先增大后减小再增大的趋势;随着距坡顶水平距离的增加,桩后侧向土压力呈倒"~"变化趋势变化,桩前侧向土压力呈"~"趋势变化。这为工程实践中框架码头岸坡的受力变形特性提供了参考依据,具有一定的现实意义。 相似文献
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针对经典朗肯、库仑土压力理论公式适用范围相对有限的问题,基于土压力理论与土坡稳定计算理论间的联系,在库仑理论的平面滑裂面假设条件下,采用微分单元化后的Bishop条分法,通过建立微元土条的水平、竖向受力平衡方程,推导出均布超载条件下的粘性土主被动土压力计算式,并给出临界破裂角的显式解答。相应简化条件下,该公式能简化为经典朗肯和库仑理论计算公式。算例分析结果表明,该公式理论计算值与试验实测值基本吻合,初步验证了公式的合理性;由于未考虑粘性填土开裂问题,现行规范方法得到的主动土压力偏小。 相似文献
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针对运用块体理论分析岩质边坡稳定性问题存在多种不确定性的混合体,提出用盲数表达具有不确定性的计算参数,将盲数理论引入楔形关键块体稳定计算方法中,给出了一种安全系数的计算方法.通过盲数运算可得到安全系数在不同取值区间内的可信度,较好地减少了因取单一值计算结果中主观因素的影响.实例研究结果表明,该方法方便灵活、有效、实用、计算结果较为可靠、合理. 相似文献
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以一矿后备区资料为基础,对矿区含煤性、煤层厚度及其变化规律进行分析,并结合邻区资料,对煤层厚度变化及控制因素进行综合分析,且利用煤的可采率和变异系数对煤层稳定性作相应评价,对矿区勘探及今后矿井开采具有指导意义。 相似文献
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针对库水位变化和降雨会使坝坡稳定性分析更为复杂的问题,基于非饱和渗流理论,借助GEO
STUDIO软件对某土石坝进行数值模拟,研究了该坝在水位骤升、水位骤降及降雨情况下坝体内的渗流情
况,以极限平衡原理和MorgensternPrice条分法为基础分析了坝坡产生滑移的最小安全系数变化规律
。结果表明,复杂水力条件下不利于坝坡的稳定性,且坝坡安全系数变化呈现出一定的规律性。 相似文献
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Hideshi Ishida Takayuki YamashitaHideo Kimoto 《International Journal of Heat and Mass Transfer》2002,45(16):3471-3476
In this study artificial disturbances were introduced into a wall plume adjacent to a vertical side wall, and its stability and chaotic characteristics were experimentally examined. The main results are: (1) for high and low frequency disturbances the neutral region (a region between stability and instability) is lower and higher values of the modified Grashof number than an analytical neutral curve, respectively. (2) As the Grashof number increases, a chaotic fluctuation of temperature is observed above a critical value. This chaotic region is completely included in the region where the wall plume is unstable. (3) The flow can be classified into four regions based on patterns, a stable region, disturbance-amplification region, chaotic region and non-chaotic region. 相似文献
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以福建省永泰滑坡为例,利用电镜试验分析了类土质滑坡土体的微观结构,掌握了降雨对类土质土体微观结构的影响,并基于数值模拟方法从宏观上研究了不同降雨模型对类土质滑坡稳定性的影响。结果表明,含水率及干湿循环对土体微观结构的影响较为显著,表现为土体含水率越高,干湿循环的次数越多,土颗粒之间的连接减弱、定向性变差及排列趋于无序,进而造成其微观结构的破坏;另外,在总降雨量保持不变的情况下,不同降雨模型对滑坡稳定性的影响也较为显著,表现为高强度降雨工况对滑坡稳定性的影响低于低强度降雨工况对滑坡的影响,前期降雨对滑坡稳定性影响最大,后期次之,中期对滑坡稳定性影响最小。 相似文献
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A multi‐body aeroelastic design code based on the implementation of the combined aeroelastic beam element is extended to cover closed loop operation conditions of wind turbines. The equations of a controller for variable generator speed and pitch‐controlled operation in high wind speeds are combined with the aeroelastic equations of motion for the complete wind turbine, in order to provide a compound aeroservoelastic system of equations. The control equations comprise linear differential equations for the pitch and generator torque actuators, the control feedback elements (proportional–integral control) and the various filters acting on the feedback signals. In its non‐linear form, the dynamic equations are integrated in time to provide the reference state, while upon linearization of the system and transformation in the non‐rotating frame, the linear stability equations are derived. Stability results for a multi‐MW wind turbine show that the coupling of the controller dynamics with the aeroelastic dynamics of the machine is important and must be taken into account in view of defining the controller parameters. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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考虑到岩质边坡失稳的连续—非连续特征,采用基于分区有限元与块体界面元混合法的强度折减法,对索风营Dr2危岩体进行稳定性分析。先应用有限元强度折减法搜索最危险滑动面,再利用分区有限元与块体界面元混合法在滑动面上生成接触点对,模拟滑动面破坏情况,然后结合强度折减法,定义接触点对全部失效时边坡失稳,计算安全系数值。结果表明,基于分区有限元与块体界面元混合法的强度折减法能够解决岩质边坡局部位移非连续问题,有效避免了目前强度折减法失稳判据的人为性,且只在滑动面上进行非线性迭代,计算效率明显提高。 相似文献
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与两端柔性直流输电(VSC-HVDC)系统相比,多端柔性直流输电(VSC-MTDC)系统更具灵活性和经济性,且有助于电力系统接纳新能源,在VSC-MTDC系统中,换流器需兼备整流器和逆变器的功能,其控制器参数会对系统的稳定性造成较大的影响,阻抗分析法可直接用于指导控制器的参数整定。为此,以一个三端系统为例,提出了适用于VSC-MTDC系统的阻抗稳定性分析方法,建立了系统的等效小信号阻抗模型,根据Nyquist判据判稳,并结合时域仿真,对直流电压控制器参数进行了分析和整定。仿真分析结果验证了所提阻抗模型和判稳方法有效、精确。 相似文献
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安全稳定控制装置是保证电力系统安全稳定运行的重要手段,现代电网的发展对稳定分析方法和稳定控制手段提出新的要求。讨论了电力市场化、电网互联和高压直流输电等现代电网发展趋势对电力系统稳定性的影响,分析了电力系统稳定分析与控制在现代电网发展中所面临的挑战,并针对性地给出若干应对措施和建议。最后对电力系统稳定分析和控制技术的发展方向进行了展望。 相似文献
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Aiming at closed-loop water system, by the method that shutting certain subcircuit, and solving the piping network, computing flow deviation of other subcircuits, then analyzing the rules of variation of stability with various factors, following conclusions are obtained: When reducing the resistance in main pipes, increasing resistance of subcircuits, system stability can be improved. Centralized regulation by changing power has no influence on system stability; centralized regulation by changing resistances will decrease system stability. Pump characteristics curve influences system stability, stability of the flat characteristic is superior to the steep one. For direct return system (DRS), the stability of subcircuit which is farthest from the heat source is the worst. For reverse return system (RRS), the stability of subcircuit in the middle of the pipe-network has the worst stability. Overall, stability of RRS is inferior to that of DRS. 相似文献