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Numerical modeling of salinity changes in marine environment of Persian Gulf is investigated in this paper. Computer simulation of the problem is performed by the solution of a convection-diffusion equation for salinity concentration coupled with the hydrodynamics equations. The hydrodynamic equations consist of shallow water equations of continuity and motion in horizontal plane. The effects of rain and evaporations are considered in the continuity equation and the effects of bed slope and friction, as well as the Coriolis effects are considered in two equations of motion. The cell vertex finite volume method is applied for solving the governing equations on triangular unstructured meshes. Using unstructured meshes provides great flexibility for modeling the flow problems in arbitrary and complex geometries, such as Persian Gulf domain. The results of evaporation and Coriolis effects, as well as imposing river and tidal boundary conditions to the hydrodynamic model of Persian Gulf (considering variable topology rough bed) are compared with predictions of Admiralty Tide Table, which are obtained from the harmonic analysis. The performance of the developed computer model is demonstrated by simulation of salinity changes due to inflow effects and diffusion effects as well as computed currents. 相似文献
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Natural Hazards - The paper presented a smoothed particle hydrodynamics (SPH) method to study the three-dimensional (3D) tidal bore scenarios. The SPH method is a mesh-free particle modeling... 相似文献
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V. B. Lapshin A. V. Patonin A. V. Ponomarev M. G. Potanina V. B. Smirnov S. M. Stroganova 《Doklady Earth Sciences》2016,469(1):705-709
A rock behavior experiment with uniaxial compression revealed the effect of acoustic activity in loaded fluid-saturated Berea sandstone samples in response to an electric current. It is established that it is substantially intensified in periods of the current impact and decreases after its cut-off. The current impact also results in a growth of radial deformation indicating an increase in the sample volume. The effect of acoustic activation increases in response to increased heat emitted by the electric current during its flow through the sample, which allows the discovered effect to be explained by initiation of its destruction due to thermal expansion of the fluid in rock interstices and fissures. 相似文献
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Overview of acoustic emission monitoring of rock structures 总被引:1,自引:0,他引:1
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岩石等脆性材料在加载过程中,随着荷载的增加,材料内部的微裂纹产生、扩展并伴随着声发射现象的发生。声发射是研究脆性材料破坏的良好工具。对砂岩、细砂岩和高丽山砂岩3类岩石进行了声发射试验,记录了加载及破坏过程中产生的声发射信号,并且采用混沌动力学理论研究了3类岩石的声发射活动规律,计算了岩石的关联维数和最大Lyapunov指数。研究结果表明,岩石加载及破坏过程具有混沌特征,用相空间重构法可以较好地揭示岩石破坏过程的动力学特征,这为混沌理论在岩石、岩体声发射其他领域的研究及应用奠定了基础。 相似文献
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研究由顶板-煤体-底板所构成的煤岩组合体变形破裂声发射和微震的规律,对于研究冲击机制具有重要意义。利用SANS材料试验系统、Disp-24声发射监测系统和TDS-6微震信号采集系统,对单轴受压的不同煤岩组合试样进行声发射和微震试验,得到不同组合试样在受载破坏过程中的声发射和微震信号。试验研究表明:组合试样发生冲击破坏时的声发射和微震信号的强度随试样的单轴抗压强度、冲击倾向性以及其顶板与煤层的高度比值的增加而增强;微震信号的振幅可以反映组合煤岩体的冲击倾向性强弱;微震频谱幅度的分布随着抗压强度和冲击能指数的上升而向高频移动。上述结论对指导现场冲击矿压的监测预警以及评价有着重要意义。 相似文献
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Pinki Hazarika Amrita Yadav Sukanta Roy 《Journal of the Geological Society of India》2017,90(6):728-732
The Koyna region located in the west coast of India is a classic example of reservoir triggered seismicity (RTS) that started soon after the impoundment of the Koyna reservoir in 1962. Previous studies have shown that RTS can be explained in terms of stress and pore pressure changes due to poroelastic response of the rock matrix. The permeability of rock matrix is a key parameter for pore pressure diffusion which is mainly responsible for generation of stress perturbation related to seismicity. Based on the poroelastic theory, we employ 2-D finite element models to simulate the evolution of pore pressure up to 5 years after the reservoir impoundment in 1962, using a range in permeability, 10?16–10?14 m2. Constraints on material properties of Deccan basalt and granitic rocks were taken from available studies. The results show the formation of pore pressure front and its propagation with depth and time since the reservoir impoundment as a function of permeability. While a permeability of 10?16 m2 does not produce any significant change in pore pressure, a ten-fold increase in permeability produces significant changes up to a depth of 2 km only beneath the reservoir after 5 years of impoundment. Permeability values between 10?15 m2 and 10?14 m2 are required to induce critical pore pressure changes in the range 0.1–1 MPa up to depth of 10 km, capable of triggering earthquakes in a critically stressed region. Studies on core samples of granitic basement rock down to a depth of 1522 m in the Koyna region provide evidences of fracture zones that may contribute to water channelization. Direct measurements of material properties through the ongoing deep drilling programme would help to develop more realistic models of RTS. 相似文献
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考虑不均质度的岩石声发射数值模拟研究 总被引:3,自引:0,他引:3
利用离散元颗粒流软件模拟了岩石单轴压缩破坏过程,采用内嵌FISH语言,通过设置随机缺陷来建立不同均质度的岩石数值试样对岩石的声发射规律进行了研究。结果表明,不均质度对于岩石声发射特性有着重要影响,随不均质度的增加,试样的峰值强度下降,声发射总数大幅增加,空间分布也更为分散,声发射出现时间更早,持续时间更长,峰值后的声发射保持更高的强度;单轴应力状态下声发射最大强度出现时间相比峰值破坏时间有不同程度滞后,不均质度越高,滞后效应越明显,显示岩石破坏要早于声发射峰值出现时间。 相似文献
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As follows from data analysis of physical modeling, the reaction of acoustic background oscillations to an external impact is well-defined under triaxial loading of a dry sandstone core in the low-frequency range (1–100 Hz). This phenomenon is explained by the generation of a low-frequency constituent of acoustic emission. A high correlation of oscillation dynamics (Klimontovich S entropy) is observed at frequencies of tens of hertz and tens of kilohertz in the absence of such a correlation in the intermediate frequency range; a synchronous increase in the oscillation level is also observed at low and high frequencies. 相似文献
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为了研究盐穴能源地下储库建造过程中,腔体围岩处在地温、卤水和地应力地质环境中盐岩的损伤演化特点,利用声发射技术分析盐岩受不同温度的饱和卤水作用后的单轴压缩损伤破坏过程。试验发现:在一定温度的饱和卤水中浸泡30 d后盐岩的单轴抗压强度和弹性模量有所降低,但降低的平均幅度很小;卤水对盐岩主要表现为溶蚀作用,而浸泡弱化作用非常小;单轴压缩过程中盐岩的应力-应变曲线与声发射-应变曲线具有较好的一致性,卤水浸泡后盐岩的累计声发射数随卤水的温度升高略有增加;卤水作用后盐岩试件的声发射率和累计数要小于无卤水作用盐岩;盐穴建造期盐岩受一定温度的卤水作用后盐岩的强度将出现一定弱化,但卤水也会促进损伤盐岩体的重结晶恢复,盐岩的这种特性有利于盐穴建造期安全和稳定。 相似文献
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岩体的声发射特征试验研究 总被引:21,自引:2,他引:21
在单轴压缩条件下,讨论了4种岩石的声发射特征;在静态胀裂剂作用下,讨论了岩体的声发射特征。研究表明,在低应力阶段,岩石几乎没有声发射活动,一般当强度达到80 %以上,即临近破坏时,声发射活动才显著增加;岩体破坏的声发射过程分为4个阶段,即初始区(Ⅰ)、剧烈区(Ⅱ)、下降区(Ⅲ)和沉寂区(Ⅳ);有的岩石的凯瑟效应不明显;岩石的声发射主频与岩石的强度有关,强度越高,主频也越高;随着应力的增加,岩石的声发射主频不会平移;应用1 kHz的探头,能满足工程岩体的稳定性分析和冒落预报的要求。 相似文献
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通过单轴加载煤岩破坏全过程声发射试验,运用多重分形消除趋势波动分析法(MF-DFA),分析了声发射强度序列的长程相关性及多重分形特征,在此基础上研究了不同应力水平下声发射强度序列长程相关指数H的变化趋势。结果表明:声发射强度时间序列内部波动不是完全随机的现象,而是由内在自相似机制决定的长程相关过程,其波动是一个有序的多重分形分布;H的变化与煤岩体的变形破坏过程能够较好的对应,声发射强度H值的“最大-减小”模式可以作为煤岩体失稳事件的前兆,这为利用声发射进行煤岩体稳定性现场监测预报提供了新的理论依据及方法 相似文献