共查询到19条相似文献，搜索用时 223 毫秒
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三角网格模型剖分方法的研究与应用 总被引：1，自引：0，他引：1
数值波场正演在地震学和勘探地球物理学领域正得到越来越广泛的应用,用一个好的方法来建立一个复杂的地质模型则显得尤为关键。三角网格模型相对于层状模型和矩形网格模型在反映地质界面形态、三角网格剖分个数调节及射线追踪速度等方面具有明显优势。利用三角网格剖分的建模方法,在VC2008编程环境下实现了复杂地质模型的描述。通过对复杂模型的建模测试,表明采用三角网格剖分方法,可解决以下模型难题：①对复杂模型界面的描述;②对复杂逆断层的描述;③对封闭块体的描述;④对模型弹性参数进行描述。 相似文献
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地层极限压力和地层流体渗流模型并不是土层的某种压力特性,而是针对冒浆问题提出的一个概念,本文通过运用土力学,岩石力学,弹塑性学,流体力学的的原理分析计算,结合摩尔库仑破坏准则进行压裂冒浆计算模型的建立,分别考虑了地层破坏极限压力和泥浆在地层中的渗流规律并建立了相应的计算模型。 相似文献
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针对光滑粒子流体动力学方法（SPH）在滑坡模拟中建立粒子模型的难题,提出了基于地理信息系统（GIS）栅格数据的粒子排列与插入方法。根据该方法,建立了滑坡SPH粒子模型及相关粒子生成程序,进一步以结合摩尔-库仑破坏准则的SPH宾汉流体模型为核心,实现了运用SPH方法模拟滑坡破坏后三维运动的过程。该SPH模型在对唐家山滑坡的模拟中得到了验证,并预测了金坪子滑坡破坏后的影响范围。结果表明：基于GIS空间数据的滑坡SPH粒子模型具有可行性与良好的适用性。以GIS数据库为基础,开展滑坡灾害的模拟研究,将大大提高对滑坡等地质灾害的仿真分析,为滑坡灾害的预测与防治提供参考。 相似文献
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将计算机图形学领域的粒子系统引入数字流域研究,研发了基于通用网格的水沙模拟时空过程三维可视化系统.该系统建立数据结构描述粒子信息和计算或者虚拟网格单元信息传递关系;采用网格控制粒子随机生成;提出局部搜索定位方法来快速确定粒子位置;通过反距离加权平方插值提取水流信息;利用自适应龙格-库塔方法实现粒子的动态变化;设计了附有更多水流属性的水体粒子;研究了流场变化过程中粒子分布不均的问题.将上述方法应用于三峡与葛洲坝间河道水流的动态可视化模拟,验证了该系统的有效性和实用性. 相似文献
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针对3DEC软件在建立滑坡模型前处理功能上的不足,本文提出了一种基于MATLAB平台构建复杂滑坡数值模型的前处理方法。以滑坡发生前后的地形数据为基础,通过Distmesh工具箱进行滑坡区域的三角网格剖分与高程插值,生成三棱柱体构建滑床与滑体。同时借助Multi-Parametric Toolbox几何库中的函数生成Voronoi多面体来模拟滑坡路径上的基底物质,编写相应函数以获取块体的拓扑信息,并依据3DEC的语法规则将其转化输出为3DEC可读取的命令文本文件,实现了复杂滑坡模型的快速建立。最后以四川省茂县新磨村滑坡为例,详细叙述了滑坡数值模型的建模步骤。数值模拟结果表明,该方法建立的模型能够较好地重现滑坡运动过程、沿程铲刮现象以及最终堆积形态,验证了该方法的可行性和实用性。 相似文献
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运用结构分析法、关键块体分析法和工程地质类比法定性评价边坡稳定性,抽取边坡岩体破坏模式。根据自制简易纵剖面仪现场绘制了结构面表面轮廓曲线,运用修正直边法和JRC—JCS模型定向统计估算结构面抗剪强度。通过对比验证定向统计估算结果与试验结果,确定计算参数取值标准。在以上两方面研究的基础上,建立边坡极限平衡计算模型,进行边坡破坏概率计算。最后,对边坡稳定性进行了综合评价。 相似文献
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超临界CO2流体具有低黏度、无表面张力的特性,若应用于非常规油气储层压裂可望实现一种无污染的新型无水压裂方法。通过建立流体在井筒内的增压速率模型,得到了考虑超临界CO2流体黏度、压缩性及增压速率的裂缝起裂压力预测模型,并与水力压裂、液态CO2压裂起裂压力进行了对比分析。结果表明,超临界CO2流体的起裂压力比液态CO2流体低20.5 %,比常规水力压裂起裂压力低75.5%;超临界CO2流体的黏度、压缩性及增压速率对裂缝起裂压力影响显著。模型与文献中试验数据对比,误差在3%以内,可为超临界CO2压裂起裂压力预测提供指导。 相似文献
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提出了一种新的无网格数值模拟计算方法--广义粒子动力学法(GPD),并在GPD算法中引入了粒子损伤理论。运用GPD方法,建立了TBM单滚刀、双滚刀作用下的完整岩体破岩模型,成功模拟了TBM滚刀破岩过程。通过与数值模拟结果及室内试验结果的对比分析,验证了GPD法模拟TBM滚刀破岩过程的有效性。同时,运用GPD方法建立了含节理岩体及高围压条件下岩体的TBM滚刀破岩模型,研究了节理及围压条件下TBM滚动破岩过程。得到了节理对TBM滚刀破岩效率的影响,既可能是促进作用又可能是抑制作用,高围压对TBM滚刀破岩过程中裂纹的起裂及扩展和破岩深度有较大的影响。 相似文献
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为探索模拟大变形自由面流体运动的高精度数值计算方法,以溃坝水流运动为例,基于MPS法(Moving Particle Semi-implicit method,移动粒子半隐式法)建立了一个垂向二维改良MPS法数值计算模型。首先,为了改善传统MPS法中存在的自由表面粒子误判以及数值能量耗散问题,提出新的自由表面粒子识别方法和高精度的压力梯度模型。在此基础上,以Lobovsky'等的溃坝物理模型实验为例,探讨不同形式压力泊松方程源项对溃坝冲击压计算精度的影响,提出一个新的源项形式。数值结果分析表明,新自由表面粒子识别方法和高精度压力梯度模型可以有效地减少自由面粒子的误判概率,抑制水流运动计算中的数值能量耗散。而压力计算结果与实验结果的对比表明,所提出的压力泊松方程源项可以有效地减少数值压力震荡的幅度。 相似文献
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《岩土力学》2017,(7):2149-2156
危岩块体的失稳多表现为突发崩塌破坏,无明显位移特征,因此常规位移监测难以达到监测预警的目的,此外影响危岩块体稳定性重要参数之一的危岩块体与母岩粘结面积难以获得,导致危岩块体稳定性评价困难。本文以危岩块体为研究对象,假设危岩块体均质各向同性,主控结构面为单个平面,系统阻尼比小于1,在振幅范围内的变形为线弹性变形,则可将危岩块体振动模型简化为弹簧振子模型。通过理论推导建立了危岩块体固有振动频率、危岩块体与母岩粘结面积、弹性模量和危岩块体质量之间的关系,再结合极限平衡模型,建立了基于固有振动频率的危岩块体稳定性评价模型。以白河堡水库右岸的危岩块体为试验对象,利用无线振动传感器(微芯方),将采集到的数据采用傅里叶变换等数学方法得到危岩块体固有振动频率,再结合固有振动频率与危岩块体粘结面积、弹性模量、危岩块体质量之间的关系,计算出块体粘结面积,最后基于该模型完成危岩块体稳定性评价。试验验证了基于固有振动频率的危岩块体稳定性评价可行性,相比传统方法更加快捷、准确。 相似文献
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The flow of water–kaolinite mixtures exhibits a non‐Newtonian nature that differs from the flow of Newtonian fluid. The varying viscosities and shear history of non‐Newtonian fluid flows necessitate the use of a rheology model in moving particle semi‐implicit (MPS) for the numerical studies. On the other hand, the Lagrangian method has the advantage of handling free surface flows with large deformation and fragmentation. This study proposes a mesh‐free Lagrangian method, namely, the MPS method, together with a simple rheology model to investigate the non‐Newtonian free surface flows. The rheological parameters required in the rheology model are determined based upon experiments. The proposed method is applied to a water–kaolinite mixture collapse problem and is proved to be capable of reproducing the significant flow features observed in laboratory experiments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Hydraulic fracturing (HF) treatment often involves particle migration and is applied for propping or plugging fractures. Particle migration behaviors, e.g., bridging, packing, and plugging, significantly affect the HF process. Hence, it is crucial to effectively simulate particle migration. In this study, a new numerical approach is developed based on a coupled element partition method (EPM). The EPM is used to model natural and hydraulic fractures, in which a fracture is allowed to propagate across an element, thereby avoiding remeshing in fracture simulations. To characterize the water flow process in a fracture, a fully hydromechanical coupled equation is adopted in the EPM. To model particle transportation in fractures with water flow, each particle is treated as a discrete element. The particles move in the fracture as a result of being dragged by fluid. Their movement, contact, and packing behaviors are simulated using the discrete element method. To reflect the plugging effect, an equivalent aperture approach is proposed. Using this method, the particle migration and its effect on water flow are well simulated. The simulation results show that this method can effectively reproduce particle bridging, plugging, and unblocking in a hydraulic fracture. Furthermore, it is demonstrated that particle plugging significantly affects water flow in a fracture and hence the propagation of hydraulic fracture. This method provides a simple and feasible approach for the simulation of particle migration in a hydraulic fracture. 相似文献
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粗粒料是一定级配的岩石颗粒集合体,具有独特的物理力学特性。以粗粒料室内三轴固结排水试验成果为基础,基于离散元颗粒流理论,从细观角度出发,以PFC3D为工具,通过自编程及二次开发,得到按级配生成的粗粒料三轴试验数值模型。引入clump颗粒考虑颗粒形状对粗粒料强度及变形的影响,分析剪胀、颗粒形状、颗粒重排的关系。结果表明：颗粒形状是影响粗粒料强度与变形的主要因素,在其他细观参数一定的情况下,改变颗粒形状,可以显著影响粗粒料的力学行为;BPM模型的应力-应变关系只在低围压下与试验值吻合,随着围压的增大,偏差越来越大;而引入clump颗粒的PFC3D数值模型能很好地模拟粗粒料室内三轴固结排水试验的应力-应变特性,但由于BPM及clump都是刚性颗粒,没有考虑颗粒变形及破碎,造成应变剪胀偏大。 相似文献
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Simulation of flow slides in municipal solid waste dumps using a modified MPS method 总被引：4，自引：1，他引：3
Flow slides in municipal solid waste (MSW) dumps have caused serious damage to structures and casualties all over the world. Therefore, much attention should be paid to this type of disaster to elucidate the flow mechanisms and fluidization characteristics of MSW, which are essential for the assessment and prevention of flowlike hazards. To bypass the deficiencies of the traditional analysis methods that use the mesh method and are based on a framework of solid mechanics, the moving particle semi-implicit (MPS) method, which is a purely Lagrangian meshless method and proposed for incompressible flow, is introduced to study flow slides in MSW landfills. Considering the no-physical pressure fluctuation that affects the simulation accuracy in the original MPS, the original MPS is revised in three ways: the kernel function, the source term of the Poisson equation and the search for free surface particles. Two benchmark problems, the dam break problem and the static pressure problem, are computed to illustrate the improvement of the pressure stability of the modified MPS. The Bingham constitutive model combined with the Mohr–Coulomb failure criterion is adopted to depict the dynamic features of MSW flow slides, and the equivalent viscosity is employed to bridge the gap between Bingham fluid models and Newtonian fluid models. This method, ultimately, is applied to simulate real flow slides in the Umraniye–Hekimbashi landfill and the Payatas waste dump. The numerical results show good consistency with the field data, indicating that the modified MPS method is capable of capturing the essential dynamic behavior and reproducing the entire process of complicated flow slides in MSW dumps. 相似文献
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Ha H. Bui Jayantha K. Kodikara Abdelmalek Bouazza Asadul Haque Pathegama G. Ranjith 《国际地质力学数值与分析法杂志》2014,38(13):1321-1340
Segmental retaining wall (SRW) systems are commonly used in geotechnical practice to stabilize cut and fill slopes. Because of their flexibility, these systems can tolerate minor movements and settlements without incurring damage or crack. Despite these advantages, very few numerical studies of large deformations and post‐failure behavior of SRW systems are found in the current literature. Traditional numerical methods, such as the finite element method, suffer from mesh entanglement, thus are unable to simulate large deformations and flexible behavior of retaining wall blocks in SRW systems. To overcome the above limitations, a novel computational framework based on the smoothed particle hydrodynamics (SPH) method was developed to simulate large deformations and post‐failure behavior of soils and retaining wall blocks in SRW systems. The proposed numerical framework is a hybrid continuum/discontinuum approach that can model soil as an elasto‐plastic material and retaining wall blocks as independent rigid bodies associated with both translational and rotational degrees of freedom. A new contact model is proposed within the SPH framework to simulate the interaction between the soil and the blocks and between the blocks. As an application of the proposed numerical method, a two‐dimensional simulation of an SRW collapse was simulated and compared to experimental results conducted under the same conditions. The results showed that the proposed computational approach provided satisfactory agreement with the experiment. This suggests that the new framework is a promising numerical approach to model SRW systems. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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以田间试验为基础,采用土壤水动力学模型,分别以自由排水、负压水头和地下水埋深三种情况作为下边界,模拟计算了灌溉农田1998年10月-2001年9月期间2 m土体的水分渗漏情况。采用地下水埋深下边界时所得到的剖面分层土壤含水量的模拟值与实测值都比较吻合,而采用自由排水和负压水头下边界时均存在不同程度的偏差。通过与定位通量法估算的水分渗漏动态及累积渗漏量做进一步比较,发现采用地下水埋深下边界时其水分渗漏的动态变化趋势与定位通量法基本一致,因此模型采用地下水埋深作为下边界比较符合当地的实际情况。 相似文献
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Weijie Zhang Kenichi Maeda Hiroshi Saito Zhaoqing Li Yu Huang 《Acta Geotechnica》2016,11(6):1401-1418
For seepage failures of dike due to water level-up and rainfall, surface infiltration and strength change induced by suction reduction are important factors; thus, numerical analysis should consider the coupling of water and soil, as well as the effect of saturation to obtain more precise failure mechanism. Based on the advanced smoothed particle hydrodynamics (SPH) method, this work proposed a two-phase-coupled SPH model in coordination with a novel constitutive model for unsaturated soils. Then, a triaxial compression test is simulated to check the applicability of the SPH method on the soil phase. After that, the failure test of a dike due to water level-up is discretized and simulated, from which the seepage process, the distribution of maximum shear strain, the slip surface, and pore water pressure are obtained. The two-phase-coupled SPH model is also applied to a slope failure test of heavy rainfall, and the results are compared to the model test. Finally, a dike failure test due to rainfall is analyzed using the proposed SPH model to reproduce the surface infiltration and suction reduction. The proposed SPH model provides several insights of seepage failures and can be a helpful tool for the analysis of dike failures induced by water level-up and rainfall. 相似文献