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1.
热流固耦合作用下页岩渗透特性实验 总被引：1，自引：0，他引：1
为探讨地温对页岩渗流特性的影响规律,按照温度对页岩作用部位的不同,从流体动能、骨架应变、吸附解吸三个方面,分析甲烷内摩擦力对动能的影响、页岩热应力及热膨胀导致应变、甲烷解吸引起基质收缩随温度变化的规律,得出热流固耦合作用下页岩渗流特性。以渝东南酉阳龙马溪组页岩样品为分析对象,进行页岩型岩的温度渗流实验,提出三方面五因素的分析方法：温度增加,流体内摩擦力增大减小了流动速度;粘土矿物与有机质的差异性膨胀产生热应力,压缩了页岩骨架,加之基质热膨胀减小了基质间隙,双重作用使渗流通道减小;基质收缩效应对孔隙裂隙双重结构介质渗透量影响很小。温度升高对页岩渗流特性的主要影响体现为,内摩擦力的减速作用及热应力和热膨胀对渗流通道的压缩作用。 相似文献
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3.
研究了降雨雨型、雨强和持时对边坡孔隙水压力分布的影响以及降雨入渗条件下饱和渗透系数的空间变异性对孔隙水压力、含水率、抗剪强度参数、局部安全系数等参数空间分布的影响。研究结果表明,降雨特性对边坡孔隙水压力的影响较大;受渗流主方向影响,降雨条件下饱和渗透系数的水平波动尺度对孔隙水压力及含水率的变异性影响小于竖向波动尺度,降雨致滑坡的临界滑面基本与坡面平行且深度较浅;随着饱和渗透系数水平波动尺度的增加,滑坡深度随之增大,从总体上坡体上部局部安全系数随饱和渗透系数竖向波动尺度的增加而减小。 相似文献
4.
运用Fluent流体分析软件,以菜籽油、辣椒颗粒和花生粒构成的多相流属性为研究对象,结合Eulerian多相流模型,研究了单斜叶桨和组合斜叶桨搅拌作用下的速度场、密度场和各单相体积分数的分布状况。结果表明:当旋转速度为5 rad/s时,在组合斜叶桨作用下,多相流的紊流特性强度增加,整体流动速度提高;近壁区的高密度聚集现象得到明显改善,混合密度均匀化程度提高;各单相的体积分数分布值与初始设定值较为接近,可以实现多相流物料的均匀性混合。计算结果对相应的多相流混合特性机理分析具有一定的理论意义和参考价值。 相似文献
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原状黄土冻融过程抗剪强度劣化机理试验分析 总被引：3，自引：0，他引：3
通过对西安Q3原状黄土在封闭系统冻融作用下的电镜扫描和直剪试验,研究了冻融作用对原状黄土微观结构和强度的影响。试验表明：冻融过程中原状黄土微观结构发生显著变化,大颗粒集粒数量明显减少,小粒径土颗粒所占比重增加,孔隙面积比增加。进一步基于损伤力学理论,得到微观结构冻融损伤度随冻融次数增加呈指数增加趋势,反映出冻融作用一定程度上破坏黄土体的结构强度,但多次冻融后黄土体结构强度趋于稳定的残余强度。冻融过程土样表面结构发生破坏,且含水率越高,土体表面特征破坏越严重。粘聚力随冻融次数增加呈指数衰减趋势,且含水率越高,粘聚力衰减幅值和速率越小;粘聚力随含水率增加表现出线性衰减特征,且冻融后粘聚力与含水率的变化规律近似重合;内摩擦角无明显规律性变化。粘聚强度冻融损伤系数随冻融次数增加呈指数增加趋势,随含水率升高有增大趋势。基于试验数据规律性,进一步提出了原状黄土粘聚强度劣化模型,该模型经试验验证可较好描述原状黄土粘聚强度劣化规律。 相似文献
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采用棱柱体试件,通过快速冻融试验方法,对冻融损伤后同配合比普通混凝土、喷射混凝土及钢纤维喷射混凝土单轴受压应力应变全曲线进行研究。对应力应变关系中相关参数进行回归分析,得出冻融循环后试件应力应变全曲线方程。结果表明：随着冻融循环次数增加,受压应力应变曲线趋于扁平;峰值应力降低,峰值应变增大,分别与冻融循环次数呈线性和指数变化。与普通混凝土相比,喷射混凝土峰值应力下降速率小,而钢纤维喷射混凝土的下降速率进一步减小。而后,采用扫描电子显微镜及压汞法,对损伤后试件微观结构和孔结构进行观察分析,发现随着冻融循环次数增加,在渗透压和冻胀压力综合作用下,试件内部微裂纹及气孔增多,孔径增大,试件密实度显著降低;而钢纤维喷射混凝土中仅出现少量连通毛细孔,这与宏观力学性能变化呈现一致性。 相似文献
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保水处理菠菜以低密度聚乙烯（LDPE）薄膜袋自然合拢不扎口包装,对照菠菜直接装在多孔塑料筐内,在RH80%、温度（2±1）℃下贮藏,研究冷藏期间大量失水（水分胁迫）对菠菜叶片叶绿素降解和活性氧代谢的影响。结果表明,冷藏期间对照菠菜失水很快,遭受严重的水分胁迫;而保水处理菠菜失水很少。与保水处理菠菜相比,水分胁迫加快了对照菠菜叶片叶绿素含量的下降速度,使超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）和谷胱甘肽还原酶（GR）活性降低,其中CAT和APX活性降低速率超过SOD,促进了过氧化物酶（POD）活性的上升,但没有明显增加丙二醛（MDA）的积累。说明水分胁迫降低了采后菠菜贮藏期间活性氧清除酶的活性,导致氧化胁迫,从而加速叶绿素的降解和衰老。 相似文献
8.
根据Muki&Sternberg的虚拟桩方法,将水平荷载作用下单桩的问题分解为弹性半空间扩展土和一根虚拟桩的叠加,其中虚拟桩的弹性模量等于桩的弹性模量与土的弹性模量之差。基于水平位移协调条件推导出求解桩土间相互作用所需要的第二类Fredholm积分方程,通过广义胡可定律推导出该积分方程间断点的显式解,从而提高了Fredholm积分方程的数值计算精度并简化了计算程序的编写,根据Mindlin解推导出位移影响函数,简化了位移函数的推导过程。参数分析表明,桩土弹性模量比对单位水平力作用下桩身最大弯矩的位置有明显的影响,随着桩刚度的增加,桩身最大弯矩的位置随之加深。 相似文献
9.
在工程实践中,直墙拱应用较多。由于拱脚位移的存在,合理假设拱脚约束为转角约束、竖向约束和水平弹性约束,应用力法推导出了在弯矩、剪力和轴力共同作用下直墙拱沿弧长的弯矩公式。研究了竖向均布荷载、竖向三角形荷载和竖向集中力荷载作用下,直墙拱沿弧长的弯矩分布及反弯点形成的规律;发现在3种荷载作用下,使得拱脚弯矩为零时的圆心角依次减小。取弹簧支座刚度为等效的下端固支、上端允许水平位移的直墙的抗推刚度,得出了随着直墙高度增加,圆弧拱拱顶弯矩增大而拱脚弯矩减小的变化规律。在直墙拱的设计中,建议选取合适的直墙高度和使得圆弧拱拱脚弯矩为零的圆心角大小,从而有利于提高结构抗弯承载力及拱脚抗剪承载力。 相似文献
10.
叶面喷施5-氨基乙酰丙酸对不同密度春玉米生长特性和产量的影响 总被引：2，自引：1，他引：1
为探讨5-氨基乙酰丙酸（5-aminolevulinic acid,ALA）对不同密度春玉米生长发育和产量的影响,以中单909为材料,在玉米9展叶时期叶面喷施100mg/L ALA,以喷施等量清水为对照,在大田条件下研究ALA对不同密度春玉米群体（45 000、75 000、105 000株/hm 2）的作用效果。结果表明：ALA处理下,玉米45 000和75 000株/hm 2密度群体产量分别比对照增加9.7%和4.9%,75 000株/hm 2密度群体千粒重和收获期单株干物质积累量分别增加3.7%和4.3%,花后叶面积指数平均增加6.8%,SPAD值比对照分别平均增加2.5%,净光合速率平均比对照高15.7%。综上所述,ALA处理改善了大田玉米的群体结构,延缓了叶片衰老进程,提高了地上部分干物质积累量,进而提高了玉米单产水平,因此可作为东北春玉米高产稳产的技术措施。 相似文献
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Based on the theory of solid and liquid coupling wave mechanics, the micro-dynamical characteristics caused by the transport of ultrasonic in porous media at near wellbore zone, including the elastic deformation of rock, the elastic crossflow of pore fluid and frame solid, and fluid squirt-flow produced by pore elastic deformation, are analyzed. Analysis of kinetics of peristaltic difference of porosity radius in porous media is presented. The characteristics of the removal of inorganic scale particle in porous media by using ultrasonic technology are also studied. Besides, by applying high power ultrasonic technology, the acoustic energy gathering in porous media at near wellbore zone leading to fracture of part rocks is illustrated. According to these analyses, the micro-dynamical mechanisms, such as inorganic scale fragmentation, ultrasonic cavitations, ultrasonic friction, ultrasonic peristaltic transport and ultrasonic fracture-making, occurred in inorganic scale plugging removal by high power ultrasonic technology are proposed. 相似文献
12.
The physical model of perilous rock avalanche excitation effect is deudofed based on the effect of the main factors, such as weight and fissure water pressure. It quantizes the interaction of perilous rock masses through the energy point of fracture mechanics and wave theory, and gains the departure rate formula of landslide body at momentary avalanche. The particle displacement rate calculation method of perilous rock medium under the action of excitation waves is developed based on the formation of perilous rock avalanche excitation waves and the spread mechanism in slope rock formation. The example shows that the analysis results established are coincident with actual situation. Some scientific basis is provided for the further research of perilous rock damage and evolutionary mechanisms. 相似文献
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《Netherlands Journal of Sea Research》1993,31(1):19-36
The distribution of fine sediments inside the Oosterschelde (Eastern Scheldt) throughout the year has been investigated. The results have been interpreted in terms of physical transport processes and activity of biotic components. Evaluation of the mechanisms that may induce landward transport of fine sediment shows that an asymmetry in maximum ebb and flood currents is probably mainly responsible for the observed landward transport of fine sediment in the Oosterschelde. A theoretical formulation is presented which fits long-term sedimentation. Transport is higher during winter than during summer. Despite a lower transport rate during summer, filter feeders do not clear Oosterschelde water. Most of the biodeposits of filter feeders are resuspended by waves and currents, probably stimulated by bioturbation and fishery. 相似文献
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《Soil Technology》1992,5(2):151-166
Soil detachment and transport by wind- driven rain differs from that by rainless wind and from that by windless rainfall. This study deals with field measurements of particle movement during periods in which rain and wind coincide. The effect of rainfall on the movement of soil particles by wind is analyzed using a sediment sensor called SALTIPHONE. Some results are presented of field experiments at two sites in the Netherlands: a cutover peat soil and a beach sand. Results show an increase of particle movement at the sensor height during rainfall. This can be attributed to the combined action of saltation and rain-induced uplift of soil particles and subsequent transport by wind. 相似文献
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为进一步探索COREX过程固体物料的运动状态,对COREX过程中涉及到的细小颗粒渗流行为进行了DEM模拟。考察不同颗粒直径比、阻尼系数及滑动摩擦系数对细小颗粒渗流行为的影响,特别是计算得到不同模拟参数下细小颗粒在填充床内的运动轨迹。模拟结果显示,渗流过程中细小颗粒的平均渗流速度为一定值。随着颗粒直径比的增加,颗粒竖直方向的渗流速度逐渐减小,停留时间与径向弥散逐渐变大。随着颗粒间阻尼系数的增加,颗粒渗流速度逐渐增加,停留时间逐渐减小,径向弥散逐渐变小。滑动摩擦系数对细小颗粒的渗流行为影响较小。从细小颗粒运动轨迹分析可知,颗粒直径比变大时,细小颗粒易在空隙中缓慢移动,易趋于静止床层中,导致颗粒沉积。随着颗粒间阻尼系数变小,颗粒运动轨迹向填充床边缘发展,偏离床层中心。 相似文献
16.
The reservoir sandstone is the sedimentary rock with many cemented sand particles. The different physical property of the reservoir even in the same area results in different mechanical response and sand production of the sandstone. Taking two types of the reservoir sandstones as research subjects, a numerical model based on 3-Dimensional Particle-based Distinct Element (PFC3D) under cylindrical coordinate system was used to simulate the micro-micro response of the sandstone considering the given confining pressure and the oil flow rate. Meanwhile, the sanding initiation and the process of the development were analyzed. The macro stress indicated that the reservoir sandstones with weaker cemented sand particles and less percent of the cemented materials would yield and fail more easily, the sand production was initiated more easily as well. Meanwhile, the stress of the parallel bonds indicated that the reservoir sandstones with granule and less cemented materials dislodged from the sandstone more easily, and the force on the particle contact was larger and the sandstone failure was more serious.Hence, the probability of the dislodged particles flowing into the wellbore was also much more. In addition, the particle displacement and rotation indicated that the physical property of the sandstone played a significant influence on the mechanical response and the sand production, the results also agreed with the above results. Therefore, the sand mechanical response and sand production of reservoir sandstone are both different due to different physical property of the reservoir. As a result, the reliable measures of the sand prediction and sand control will be adopted based on the reservoir physical property and conditions. 相似文献
17.
Investigations of the particle motion characteristics in the gas solid two phase wake of leeward side circular cylinder 总被引：1，自引：0，他引：1
This paper investigates the characteristics of the particle motion in circular cylinder wake flow of leeward side by simulating the micro particle flow around circular cylinder using Euler two fluid model combined with Reynolds stress model. It compares the particle velocity and concentration of different particle size in the leeward area. The results show that the vortex is formed after the gas flowed passing the cylinder, and the concentration and velocity of particles are affected by the turbulent intensity in the leeward side. Gas entrainment vortex and particles own inertia decide the flow form of fine particle around the cylinder. Both effects impact the particle concentration distribution of different size particles in the leeward area. With the increase of particle size, the particle concentration increases at the beginning and then decreases in the leeward area. 相似文献
18.
The gas-solid two-phase flow characteristics of fine particles in the filter media were simulated based on CFD-DEM (Discrete Element Method) in this study, and the particle group, particle size distribution, and the rebound effect between particles, particle and fiber were taken into account the calculations. Additionally, the movement characteristics of the particle group and the deposition form of the fine particles in the fibrous filtration were analyzed. The results indicate that it is convenient and feasible to simulate the filtration process of the filter media as well as the deposition process and form of the fine particle on the media surface using CFD-DEM, and the simulation results are consistent with the experimental observations in the literature. The surface filtration has larger contribution to the filtration process, and most of the particles are captured by the media surface. Meanwhile, parts of smaller particles that enter into the media are captured by the depth filtration. A larger number of particles are collected by the particle-particle capture mechanism. The filtration efficiencies of the filter media are varied with the particle systems, and for the model of the filter media in this study, the filtration efficiency of the multi-particle system is about 20% higher than that of the single-particle one. 相似文献
19.
Effect of Consolidation Pressure and Adsorption Parameter on Contaminant Transport Considering the Biodegradation of Contaminant at Source 总被引：1，自引：0，他引：1
Consolidation deformation can lead to changes of structural and permeable characteristics of clay impermeable layer, which will affect the distribution of seepage field and concentration field, and then affect the transport law of contaminant in impermeable layer. Based on the Biot consolidation theory, the transport law of contaminant in deforming soil is studied taking account. Meanwhile, the effects of consolidation pressures and adsorption parameters have been analyzed separately. The results show that consolidation deformation retards the transport process of contaminant and shortens the transport depth of contaminant. In addition, the retardation of consolidation deformation on the transport process of contaminant becomes stronger as the consolidation pressure increases. Meanwhile, under the condition of a linear adsorption mode, the decreasing rate of migration depth increases gradually as the adsorption parameter decreases. It is shown that the retardation of consolidation deformation on the transport process of contaminant becomes more visible when the adsorption parameter decreases. The results have important theoretical significance for the design of effective thickness of the simple constructed garbage dump and bottom sediment dump, as well as the safety evaluation of impermeable layer. 相似文献
20.
以弧形筛为研究对象,分析不同筛缝规格、安装角度以及水处理量条件下对固体颗粒物的去除效果,以获得最优化的结构设计参数。将固体颗粒物去除率作为试验指标,设计了0.10~0.25 mm的筛缝间隙、10~20 m3/h 的进水流量及53°和37°的筛网安装角度的多因素试验。结果显示,随着筛缝间隙的增大,固体颗粒物去除率呈逐渐下降趋势,但筛缝间隙与颗粒物粒径具有明显的“匹配性”特征,筛缝间隙应以等于或略小于水体中平均固体颗粒物粒径为宜;进水流量与固体颗粒物去除率呈反相关关系,单位面积筛面的水处理负荷宜控制在50 m3/(m2?h)左右;在合理的筛网安装角度范围内,适当增大安装倾角有利于提高固体颗粒物去除率。总之,将弧形筛装置应用在水产养殖系统中,是一种行之有效的方法。 相似文献