scholarly journals An Investigation of Rainfall-Induced Landslides From the Pre-Failure Stage to the Post-Failure Stage Using the Material Point Method

2021 ◽  
Vol 9 ◽  
Author(s):  
Wei-Lin Lee ◽  
Mario Martinelli ◽  
Chjeng-Lun Shieh
Keyword(s):  
Numerical Model ◽  
Pore Water ◽  
Numerical Solutions ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Failure Behavior ◽  
Clear Understanding

The kinematic behavior of rainfall-induced landslides from the pre-failure stage to post-failure stage contains important information for risk assessment and management. Because a complex relationship exists between rainfall conditions, pore water pressure, soil strength, and movement rates, a numerical model is the most efficient way to investigate the behavior of rainfall-induced landslides. In this study, the material point method (MPM) is used to investigate the dynamic behavior of landslides. First, the rainfall boundary conditions are extensively verified by comparing 1-D consolidation tests against other numerical solutions. Then, a numerical model is used to simulate a lab-scale rainfall-induced slope failure. A parametric study shows the influence of rainfall intensity on pore water pressure development, failure triggering time, surface displacement, and velocity. The use of the MPM provides a clear understanding in the failure mechanism and post-failure behavior of a rainfall-induced landslide.

scholarly journals Analysis of the Slope Response to an Increase in Pore Water Pressure Using the Material Point Method

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1446 ◽  
Author(s):  
Troncone ◽  
Conte ◽  
Pugliese
Keyword(s):  
Pore Water ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Numerical Technique ◽  
Water Pressure ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Major Influence ◽  
Preliminary Evaluation

Traditional numerical methods, such as the finite element method or the finite difference method, are generally used to analyze the slope response in the pre-failure and failure stages. The post-failure phase is often ignored due to the unsuitability of these methods for dealing with problems involving large deformations. However, an adequate analysis of this latter stage and a reliable prediction of the landslide kinematics after failure are very useful for minimizing the risk of catastrophic damage. This is generally the case of the landslides triggered by an excess in pore water pressure, which are often characterized by high velocity and long run-out distance. In the present paper, the deformation processes occurring in an ideal slope owing to an increase in pore water pressure are analyzed using the material point method (MPM) that is a numerical technique capable of overcoming the limitations of the above-mentioned traditional methods. In particular, this study is aimed to investigate the influence of the main involved parameters on the development of a slip surface within the slope, and on the kinematics of the consequent landslide. The obtained results show that, among these parameters, the excess water pressure exerts the major influence on the slope response. A simple equation is also proposed for a preliminary evaluation of the run-out distance of the displaced soil mass.

Long-wave-induced flows in an unsaturated permeable seabed

2007 ◽  
Vol 586 ◽  
pp. 323-345 ◽  
Author(s):  
PHILIP L.-F. LIU ◽  
YONG SUNG PARK ◽  
JAVIER L. LARA
Keyword(s):  
Diffusion Equation ◽  
Pore Water ◽  
Analytical Solutions ◽  
Numerical Solutions ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Column ◽  
Seepage Flows ◽  
Dimensional Diffusion ◽  
Special Cases

We present both analytical and numerical solutions describing seepage flows in an unsaturated permeable seabed induced by transient long waves. The effects of compressibility of pore water in the seabed due to a small degree of unsaturation are considered in the investigation. To make the problem tractable analytically, we first focus our attention on situations where the horizontal scale of the seepage flow is much larger than the vertical scale. With this simplification the pore-water pressure in the soil column is governed by a one-dimensional diffusion equation with a specified pressure at the water–seabed interface and the no-flux condition at the bottom of the seabed. Analytical solutions for pore-water pressure and velocity are obtained for arbitrary transient waves. Special cases are studied for periodic waves, cnoidal waves, solitary waves and bores. Numerical solutions are also obtained by simultaneously solving the Navier–Stokes equations for water wave motions and the exact two-dimensional diffusion equation for seepage flows in the seabed. The analytical solutions are used to check the accuracy of the numerical methods. On the other hand, numerical solutions extend the applicability of the analytical solutions. The liquefaction potential in a permeable bed as well as the energy dissipation under various wave conditions are then discussed.

scholarly journals Numerical Simulation of Mesodamage Behavior of Concrete Based on Material Point Method

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Aihua Liu ◽  
Jiaqiang Zou ◽  
Wei Hu ◽  
Ming Liu ◽  
Peitong Cong ◽  
...  
Keyword(s):  
Numerical Model ◽  
Constitutive Model ◽  
Mechanical Behavior ◽  
Uniaxial Tension ◽  
Material Point Method ◽  
Material Point ◽  
Point Method ◽  
Damage Initiation ◽  
Numerical Tests ◽  
Random Aggregate

Concrete consists of coarse aggregates, mortar matrix, and interfacial transition zone (ITZ) between them at the mesoscale. Considering these three phases, many numerical tests have been conducted to study the mesodamage behavior of concrete, in which a variety of numerical methods have also been adopted. These methods are mainly based on the finite element method (FEM); however, some other methods have been proven to be helpful as well. For example, the material point method (MPM) has the advantage of building a numerical model based on pixel or voxel of the image and is capable of solving large deformation problems. In view of this, MPM is introduced in this paper. Firstly, a method for establishing the numerical specimen is put forward, considering the original sample of its mesoscopic geometric character. Then, a stochastic damage constitutive model considering the heterogeneity of the concrete is proposed. Next, the numerical model and the constitutive model are incorporated into an MPM code to conduct numerical tests. The uniaxial tension and compression tests of a random-aggregate model and a double-aggregate specimen under uniaxial tension are then simulated numerically to validate the proposed method. Results show that the proposed method can well capture the main macroscopic mechanical behavior of concrete and the mesoscopic damage initiation and propagation. It is also found that MPM can save the time of model establishing and improve calculation efficiency. The influences of different parameters of the proposed constitutive model are also clarified through a parametric study. The proposed method can provide a useful tool for concrete numerical testing and for studying the mechanical behavior of concrete at mesoscale.

scholarly journals NUMERICAL MODELING OF UNSATURATED LAYERED SOIL FOR RAINFALL-INDUCED SHALLOW LANDSLIDES

2017 ◽  
Vol 25 (4) ◽  
pp. 329-341 ◽  
Author(s):  
Chih-Yu LIU ◽  
Cheng-Yu KU ◽  
Jing-En XIAO ◽  
Chi-Chao HUANG ◽  
Shih-Meng HSU
Keyword(s):  
Numerical Modeling ◽  
Slope Stability ◽  
Pore Water ◽  
Numerical Solutions ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Characteristic Curve ◽  
Shallow Landslides ◽  
Layered Soil ◽  
Richards Equation

In this paper, a pioneer study on numerical modeling of rainfall-induced shallow landslides in unsaturated layered soil using the variably saturated flow equation is presented. To model the shallow landslides, the infinite slope stability analysis coupled with the hydrological model with the consideration of the fluctuation of time-dependent pore water pressure and Gardner equation for soil water characteristic curve was developed. A linearization process for the nonlinear Richards equation to deal with groundwater flow in unsaturated layered soil is derived using the Gardner model. To solve one-dimensional flow in the unsaturated zone of layered soil profiles, flux conservation and the continuity of pressure potential at the interface between two consecutive layers are considered in the numerical discretization of the finite difference method. The validity of the proposed model is established in three numerical problems by comparing the results with the analytical and other numerical solutions. Application examples have also been conducted. Obtained results demonstrate that the fluctuation of pore water pressure in unsaturated layered soil dominates slope stability of landslides and the lowest factor of safety may occur at the interface between two consecutive layers. The findings observed in this study are a fundamental contribution to environmental protection engineering for landslides in areas with higher occurrence and vulnerability to extreme precipitation.

scholarly journals Towards an understanding of the chemo-mechanical influences on kidney stone failure via the material point method

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0240133
Author(s):  
Samuel J. Raymond ◽  
Janille Maragh ◽  
Admir Masic ◽  
John R. Williams
Keyword(s):  
Kidney Stones ◽  
Complex Structure ◽  
Material Point Method ◽  
Renal Calculi ◽  
Material Point ◽  
Point Method ◽  
Tensile Fracture ◽  
Failure Behavior ◽  
Failure Patterns ◽  
Extracorporeal Shock Wave

This paper explores the use of the meshfree computational mechanics method, the Material Point Method (MPM), to model the composition and damage of typical renal calculi, or kidney stones. Kidney stones are difficult entities to model due to their complex structure and failure behavior. Better understanding of how these stones behave when they are broken apart is a vital piece of knowledge to medical professionals whose aim is to remove these stone by breaking them within a patient’s body. While the properties of individual stones are varied, the common elements and proportions are used to generate synthetic stones that are then placed in a digital experiment to observe their failure patterns. First a more traditional engineering model of a Brazil test is used to create a tensile fracture within the center of these stones to observe the effect of stone consistency on failure behavior. Next a novel application of MPM is applied which relies on an ultrasonic wave being carried by surrounding fluid to model the ultrasonic treatment of stones commonly used by medical practitioners. This numerical modeling of Extracorporeal Shock Wave Lithotripsy (ESWL) reveals how these different stones failure in a more real-world situation and could be used to guide further research in this field for safer and more effective treatments.

Pore Water Pressure Response of Fully Saturated Soil Beds during Earthquake–Tsunami Multi‐Hazards

2019 ◽  
Vol 109 (5) ◽  
pp. 1785-1796 ◽  
Author(s):  
Yingqing Qiu ◽  
Henry Benjamin Mason
Keyword(s):  
Numerical Model ◽  
Pore Water ◽  
Numerical Experiments ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Coastal Areas ◽  
Soil Liquefaction ◽  
Beach Sand ◽  
Liquefaction Potential ◽  
Quiescent Period

Abstract Soil liquefaction causes significant damage to coastal infrastructure and buildings worldwide. Strong earthquake shaking can cause soil liquefaction in fully saturated sand deposits. Also, tsunamis can induce liquefaction, as well as enhanced sediment transport and scour, in coastal areas. To understand soil liquefaction potential during an earthquake–tsunami multi‐hazard, we develop a numerical model to predict the multi‐hazard induced excess pore water pressures. We calibrate and verify the numerical model by comparing results with laboratory experiments. Then, we perform numerical experiments using a recorded earthquake motion and hypothetical tsunami wave heights. The numerical experiments show that beach sand liquefies during earthquake loading. The sand then resediments during the quiescent period and the tsunami runup stage. Finally, during rapid tsunami drawdown, liquefaction can occur again, and liquefaction potential during tsunami drawdown primarily depends on the soil’s hydraulic conductivity, as well as the duration of the quiescent period. The results emphasize the need for predictions of earthquake–tsunami loading, as well as measurements of soil properties in coastal areas.

scholarly journals Modelling of Post-flotation Tailings Liquefaction Induced by Paraseismic Events

2016 ◽  
Vol 63 (2-3) ◽  
pp. 215-233 ◽  
Author(s):  
Waldemar Świdziński
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Pore Water ◽  
Seismic Activity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Model Parameters ◽  
Storage Facility ◽  
Horizontal Acceleration ◽  
Numerical Tests

AbstractThis paper presents and discusses the results of numerical modelling of pore water pressure build-up in post-flotation saturated tailings deposited at the Tailings Storage Facility “Żelazny Most”, caused by seismic-induced dynamic loading. Numerical simulations were based on the compaction/liquefaction model proposed by A. Sawicki. The model parameters were determined in the laboratory for tailings sampled at the TSF “Żelazny Most”. The sensitivity of the numerical model was verified in a series of numerical tests for various horizontal acceleration amplitudes. In the main calculations, an accelerogram recorded during a real paraseimic event was assumed. The results obtained show that, with the current seismic activity near the TSF “Żelazny Most”, some pore water pressure is generated within the saturated tailings layer, but it does not trigger the liquefaction phenomenon.

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

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