• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.13 no.5
• /
• pp.419-424
• /
• 2020

Poroelasticity theory has been widely used for detecting cancellous bone deterioration because of the safe use for humans. The tortuosity itself is an important indicator for ultrasound detection for bone diseases. The transport properties of cancellous bone are also important in bone mechanotransduction. In this paper, two important factors, the wave velocity and attenuation are examined for permeability (or tortuosity). The theoretical calculation for the relationship between the wave velocity (and attenuation) and permeability (or tortuosity) for cancellous bone is shown in this study. It is found that the wave along the solid phase (trabecular struts) is influenced not by tortuosity, but the wave along the fluid wave (bone fluid phase) is affected by tortuosity significantly. However, the attenuation is different that the attenuation of a fast wave has less influence than that of a slow wave because the slow wave is observed by the relative motion between the solid and fluid phases.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.1078-1080
• /
• 2002

The pressure variation of interstitial fluid is one of the most important factors in bone physiology. In order to understand the role of interstitial fluid and the biomechanical interactions between fluid and solid constituents within bone, poroelastic theory was applied. The purpose of this study is to describe the behavior of calf vertebral trabecular bone composed of the porous solid trabeculae and the viscous bone marrow by using a commercial finite element analysis program based on the poroelasticity. In this study, the model was numerically tested for 5 different strain rates, i. e., 0.001, 0.01, 0.1, 1.0, and 10 per second. The material properties of the calf vertebral trabecular bone were utilized from the previous experimental study. Two asymptotic poroelastic response, the drained and undrained deformation, were predicted. From the predicted results for the simulated five strain rate, it was found that the pore pressure generation has a linearly increasing behavior when the strain rate is the highest at 10 per second, other wise it showed a nonlinear the strain rate Increased. Based on the results of the present study, it was suggested that the calf vertebral trabecular bone could be modeled as a porous material and its strain rate dependent material behavior could be predicted.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.519-526
• /
• 2000

강수량 변동에 따른 사면 내의 지하수유동과 사면의 안정성 변화를 동시에 분석.평가하기 위하여 하나의 완전 연동된 수리지질역학적 모델을 제시하였다. 이 모델은 변형성 지질매체 내에서의 지하수유동을 설명하는 일련의 지배식들과 Galerkin 유한요소법에 기초하여 개발되었다. 1990년부터 1999년까지의 서울지역의 건기 (1월) 및 우기 (8월) 강수량 하에 있는 토양 사면에 대해 개발된 모델을 적용하여 일련의 수치실험을 실시하였다. 수치실험의 결과는 강수량이 증가함에 따라 사면의 수리역학적 안정성이 전반적으로 악화됨을 보여준다. 즉 강수량이 증가할수록 공극수압이 증가하고 지하수면이 상승한다. 그 결과 불포화대가 축소되고 삼출면이 팽창되며 사면의 전단부를 따라 지하수유동속도가 증가하게 된다. 동시에 강수량이 증가할수록 사면 전단부를 향해 전반적인 변위량이 증가한다. 그 결과 안전율이 1 이하인 불안전한 지역이 사면 전단부에서 사면 상부 쪽으로 전파.팽창되며 그 두께도 증가한다. 수치실험의 결과는 또한 사면의 표면에서는 전단파괴와 더불어 인장파괴도 발생할 수 있음을 보여준다.

• Journal of Mechanical Science and Technology
• /
• v.15 no.7
• /
• pp.1032-1040
• /
• 2001

It is widely accepted that the pressure variation of interstitial fluid is one of the most important factors in bone physiology. In order to understand the role of interstitial fluid on porous bony structure, a consideration for the biomechanical interactions between fluid and solid constituents within bone is required. In this study, a poroelastic theory was applied to investigate the elastic behavior of calf vertebral trabecular bone composed of the porous solid trabeculae and the viscous bone marrow. The poroelastic behavior of trabecular bone in a uniaxial stress condition was simulated using a commercial finite difference analysis software (FLAC, Itasca Consulting Group, USA), and tested for 5 different strain rates, i.e., 0.001, 0.01, 0.1, and 10 per second. The material properties of the calf vertebral trabecular bone were utilized from the previous experimental study. Two asymptotic poroelastic responses, the drained and undrained deformations, were predicted. From the predicted results for the simulated five strain rates, it was found that the pore pressure generation has a linearly increasing behavior when the strain rate is the highest at 10 per second, otherwise it showed a nonlinear behavior. The pore pressure generation with respect to the strain was found to be increased as the strain rate increased. The elastic moduli predicted at each strain were 208.3, 212.2, 337.6, 593.1, and 602.2 MPa, respectively. Based on the results of the present study, it was suggested that the calf vertebral trabecular bone could be modeled as a poroelastic material and its strain rate dependent material behavior could be predicted.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.6
• /
• pp.5-16
• /
• 2002

A hydrogeomechanical numerical model is presented to evaluate rainfall impacts on groundwater flow in slopes and slope stability. This numerical model is developed based on the fully coupled poroelastic governing equations for groundwater flow in deforming variably saturated geologic media and the Galerkin finite element method. A series of numerical experiments using the model developed are then applied to an unsaturated slope under various rainfall rates. The numerical simulation results show that the overall hydromechanical slope stability deteriorates, and the potential failure nay initiate from the slope toe and propagate toward the slope crest as the rainfall rate increases. From the viewpoint of hydrogeology, the pressure head and hence the total hydraulic head increase as the rainfall rate increases. As a result, the groundwater table rises, the unsaturated zone reduces, the seepage face expands from the slope toe toward the slope crest, and the groundwater flow velocity increases along the seepage face. From the viewpoint of geomechanics, the horizontal displacement increases, and the vertical displacement decreases toward the slope toe as the rainfall rate increases. This may result from the buoyancy effect associated with the groundwater table rise as the rainfall rate increases. As a result, the overall deformation intensifies toward the slope toe, and the unstable zone, in which the factor of safety against shear failure is less than 1, becomes thicker near the slope toe and propagates from the slope toe toward the slope crest. The numerical simulation results also suggest that the potential tension failure is likely to occur within the slope between the potential shear failure surface and the ground surface.