Three‐dimensional ridge collapse mechanism for narrow soil slopes

2021 ◽  
Author(s):  
Radoslaw L. Michalowski ◽  
Dowon Park
Keyword(s):  
Three Dimensional ◽  
Collapse Mechanism ◽  
Soil Slopes

Analyses of groundwater flow and plant evapotranspiration in a vegetated soil slope

2013 ◽  
Vol 50 (12) ◽  
pp. 1204-1218 ◽  
Author(s):  
A.K. Leung ◽  
C.W.W. Ng
Keyword(s):  
Groundwater Flow ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Root Water Uptake ◽  
Dry Season ◽  
Climatic Data ◽  
Wet Season ◽  
Soil Slopes ◽  
Transient Seepage

Understanding seasonal hydrogeological responses of vegetated soil slopes is vital to slope stability because pore-water pressure (PWP) varies from positive values upon rainfall in wet seasons to negative values upon plant evapotranspiration (ET) in dry seasons. There are, however, few case histories that report seasonal performance of vegetated soil slopes. In this study, a vegetated slope situated in Hong Kong was instrumented to analyse (i) groundwater flow during rainfall in the wet season and (ii) effects of plant ET on PWP in the dry season. Two- and three-dimensional anisotropic transient seepage analyses are conducted to identify groundwater flow mechanism(s) during a heavy rainstorm. Through water and energy balance calculations, measured plant-induced suction is interpreted with plant characteristic and climatic data. During the rainstorm, substantial recharge of the groundwater table was recorded, likely due to preferential water flow along relict joints and three-dimensional cross-slope groundwater flow. During the dry season, the peak suction induced by plant ET is up to 200 kPa and the depth of influence is shallower than 200% of the root depth. For the range of suctions monitored, root-water uptake is revealed to have been restricted by suction not very significantly and was driven mainly by the climatic variation.

Temperate Alpine glacier surface dynamics linked to collapsing subglacial conduits

2021 ◽  
Author(s):  
Pascal Egli ◽  
Stuart Lane ◽  
James Irving ◽  
Bruno Belotti
Keyword(s):  
Three Dimensional ◽  
Swiss Alps ◽  
Glacier Retreat ◽  
Collapse Mechanism ◽  
Glacier Mass Balance ◽  
Glacier Surface ◽  
Alpine Glacier ◽  
Surface Loss ◽  
Ice Surface ◽  
Surface Melt

<p>If tongues of temperate Alpine glaciers are subjected to high temperatures their topography may change rapidly due to the effects of differential melt related to aspect and debris cover. Independent of local surface melt, the position of subglacial conduits may have an important influence on ice creep and so on changes in topography at the ice surface. This reflects analyses that suggest that subglacial conduits at glacier margins may not be permanently pressurised; and that creep closure rates are insufficient to close subglacial conduits completely. Rapid climate warming may exacerbate this process, due both to surface-melt driven glacier thinning and over-enlargement of conduits due to high upstream melt rates. Over-enlarged conduits that are not permanently pressurised would lead to the development of structural weaknesses and eventual collapse of the ice surface into the conduits. We hypothesise that this collapse mechanism could represent an important and alternative driver of rapid glacier retreat.</p><p>In this paper we combine: (1) an extensive survey of glacier margin collapse in the Swiss Alps with (2) intensive monitoring of the dynamics of such collapse at the Otemma Glacier in the south-western Swiss Alps. Daily UAV surveys were undertaken at a high spatial resolution and with precise and accurate ground control. These datasets were used to generate surface change information using SfM-MVS photogrammetry. Surfaces of difference showed surface loss that could not be related to ablation alone. Combining them with three-dimensional ground-penetrating radar (GPR) surveys in the same zone showed that the surface loss was coincident spatially with the positions of sub-glacial conduits, for ice thicknesses between 20 m and 50 m. We show that this form of subglacial conduit collapse is also happening for several other glaciers in the Swiss Alps, and that this mechanism of snout collapse and glacier retreat has become more common than has hitherto been the case. It also leads to temporal patterns of glacier margin retreat that differ from those that might be expected due to glacier mass balance and ice mass flux effects alone.</p>

Kinematic limit analysis of three-dimensional unsaturated soil slopes reinforced with a row of piles

2020 ◽  
Vol 120 ◽  
pp. 103428 ◽  
Author(s):  
Long Wang ◽  
De'an Sun ◽  
Yangping Yao ◽  
Lizhou Wu ◽  
Yongfu Xu
Keyword(s):  
Unsaturated Soil ◽  
Limit Analysis ◽  
Three Dimensional ◽  
Kinematic Limit ◽  
Soil Slopes

Determination of three-dimensional shape of failure in soil slopes

2015 ◽  
Vol 52 (9) ◽  
pp. 1283-1301 ◽  
Author(s):  
Roohollah Kalatehjari ◽  
Ali Arefnia ◽  
Ahmad Safuan A Rashid ◽  
Nazri Ali ◽  
Mohsen Hajihassani
Keyword(s):  
Slope Stability ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Three Dimensional ◽  
Failure Surface ◽  
Small Scale ◽  
3D Shape ◽  
Finite Element Software ◽  
Soil Slopes ◽  
3D Slope Stability

This paper presents the application of particle swarm optimization (PSO) in three-dimensional (3D) slope stability analysis to determine the shape and direction of failure as the critical slip surface. A detailed description of adopted PSO is presented and a rotating ellipsoidal shape is introduced as the possible failure surface in the analysis. Based on the limit equilibrium method, an equation of factor of safety (FoS) was developed with the ability to calculate the direction of sliding (DoS) in its internal process. A computer code was developed in Matlab to determine the 3D shape of the failure surface and calculate its FoS and DoS. Then, two example problems were used to verify the applicability of the presented code, the first by conducting a comparison between the results of the code and PLAXIS-3D finite element software and the second by re-analyzing an example from the literature to find the 3D failure surface. In addition, a hypothetical 3D asymmetric slope was introduced and analyzed to demonstrate the ability of the presented method to determine the shape and DOS of failure in 3D slope stability problems. Finally, a small-scale physical model of a 3D slope under vertical load was constructed and tested in the laboratory and the results were re-analyzed and compared with the code results. The results demonstrate the efficiency and effectiveness of the presented code in determining the 3D shape of the failure surface in soil slopes.

Analytical Study of Seismic Progressive Collapse in a Steel Moment Frame Building

2012 ◽  
Vol 446-449 ◽  
pp. 102-108
Author(s):  
Niloofar Parsaeifard ◽  
Fariborz Nateghi Alahi
Keyword(s):  
Progressive Collapse ◽  
Three Dimensional ◽  
The Other ◽  
Nonlinear Static Analysis ◽  
Collapse Mechanism ◽  
Three Dimensional Model ◽  
Steel Moment Frame ◽  
Collapse Potential ◽  
Frame Building ◽  
Ductile Behavior

Progressive collapse is defined as total or remarkable partial collapse of structure following the damage occurred at a small portion of the structure. In most cases, the study is focused on progressive collapse of structures due to explosion, vehicle impact, fire and other man-made hazards; with less attention on progressive collapse mechanism of structure due to earthquake. Although the post earthquake inspections show that structural elements, mostly columns in the corner of the plan, can be severely damaged during earthquake. If neighboring columns are not properly designed to resist and redistribute the additional gravity load that is imposed by the column loss, partial collapse of the structure will occur; which would lead to progressive collapse of the structure. In this regard, progressive collapse potential of a moment resisting steel building is investigated via analytical procedure under earthquake action. In this research, a corner-column of the building was weakened intentionally to navigate the damage toward a certain part of the structure. Then, nonlinear static analysis is carried out on the three dimensional model of the building and the total behavior of the structure is studied. The results indicate that after the failure of the corner-column, the lateral resistance of the frame in which the removed (failed) column was located decreases, and the failure of the other columns occurs. Large plastic deformations and the failure of the other members could cause progressive collapse in the whole structure and the expected ductile behavior of the structure would not be observed.

Prediction of evaporation from soil slopes

2006 ◽  
Vol 43 (8) ◽  
pp. 815-829 ◽  
Author(s):  
B Weeks ◽  
G W Wilson
Keyword(s):  
Solar Radiation ◽  
Water Balance ◽  
Soil Cover ◽  
Three Dimensional ◽  
Net Radiation ◽  
Digital Map ◽  
Pore Water Pressures ◽  
Soil Slopes ◽  
Cover Systems ◽  
Geotechnical Problems

The calculation of evaporation from soil surfaces is of critical importance in predicting the surface water balance for soil cover systems constructed on waste disposal sites and for geotechnical problems where the prediction of pore-water pressures is important. There are several well-established approaches available for predicting evaporation from horizontal soil surfaces, but the issues that affect evaporation from soil slopes have not been fully investigated for geotechnical applications. The importance of variations in solar radiation with respect to evaporation from soil slopes is examined here, and a method to predict the solar radiation on soil slopes is presented. The method is applied to a fully three-dimensional surface, based on the digital map of a soil cover placed at a mine site, to illustrate variations in potential evaporation over the surface of the site. The implication of radiation variations for actual evaporation on slopes is also illustrated. The results show that north-facing slopes at greater latitudes in the northern hemisphere can receive significantly less net radiation than horizontal or south-facing slopes, resulting in less actual evaporation.Key words: slope, evaporation, solar energy, soil cover, water balance.

scholarly journals Wind-induced collapse analysis of long-span transmission tower–line system considering the member buckling effect

2018 ◽  
Vol 22 (1) ◽  
pp. 30-41 ◽  
Author(s):  
Li Tian ◽  
Haiyang Pan ◽  
Canxing Qiu ◽  
Ruisheng Ma ◽  
Qiqi Yu
Keyword(s):  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Bending Moment ◽  
Element Model ◽  
Collapse Mechanism ◽  
Transmission Tower ◽  
Line System ◽  
Long Span ◽  
Collapse Analysis ◽  
Three Dimensional Finite Element

The collapse problem of transmission tower upon strong winds was well noted in past few years. This article analyses the wind-induced collapse problem of a long-span transmission tower–line system. The member buckling effect was particularly considered. In doing so, a three-dimensional finite element model of the long-span transmission tower–line system was established in ABAQUS based on a practical project. The transmission tower and line were simulated by the frame and truss elements, respectively. The nonlinear behavior of a compressive member was simulated using the Marshall model, and the nonconvergence of numerical calculation was set to be the collapse criterion. The critical wind speed, damage position, and collapse probability were obtained from a collapse analysis of the long-span transmission tower–line system under different wind attack angles. The collapse mechanism of the long-span transmission tower–line system under a wind attack angle of 45° was investigated, and an incremental dynamic analysis was performed to evaluate the collapse-resistant capacity of the transmission tower. The study reveals that the interaction between bending moment and shear deformation is critical to the collapse of transmission tower.

scholarly journals The Contribution of Particle Swarm Optimization to Three-Dimensional Slope Stability Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Roohollah Kalatehjari ◽  
Ahmad Safuan A Rashid ◽  
Nazri Ali ◽  
Mohsen Hajihassani
Keyword(s):  
Particle Swarm Optimization ◽  
Stability Analysis ◽  
Slope Stability ◽  
Three Dimensional ◽  
Particle Swarm ◽  
Slope Stability Analysis ◽  
Swarm Optimization ◽  
Finite Element Software ◽  
Soil Slopes ◽  
3D Slope Stability

Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes.

Three-dimensional upper-bound analysis for ultimate bearing capacity of laterally loaded rigid pile in undrained clay

2015 ◽  
Vol 52 (11) ◽  
pp. 1775-1790 ◽  
Author(s):  
Jian Yu ◽  
Maosong Huang ◽  
Chenrong Zhang
Keyword(s):  
Bearing Capacity ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Upper Bound ◽  
Three Dimensional ◽  
Soil Conditions ◽  
Soil Parameters ◽  
Collapse Mechanism ◽  
Layered Soils ◽  
Rigid Plastic

A new three-dimensional upper-bound combined failure mechanism is presented to analyze the lateral ultimate capacity of rigid piles embedded in various soil conditions, involving homogeneous soils, layered soils, and Gibson soils. The wedge curved failure surface function composed by rotating the Newton interpolation polynomial is adopted near the ground surface, and a plane strain collapse mechanism is employed at depth. Furthermore, the energy dissipation of the transition interface is introduced to keep a kinematically admissible velocity field between the wedge and the plane strain mechanism. An empirical equation is then proposed based on the upper-bound solutions for the homogeneous soils, and extended to the layered soils and Gibson soils. Meanwhile, the three-dimensional arbitrary Lagrangian–Eulerian (ALE) analysis is employed to investigate the distribution of limiting pressures along the pile shaft for different soil parameters. It is found that the upper-bound solutions based on the rigid-plastic assumption only exhibits a good agreement with the finite element (FE) results for a very high soil rigidity index of 10 000, due to a Possion’s ratio of approximate but less than 0.5 in such a typical undrained FE analysis. For such a Possion’s ratio, an inevitably slight elastic volumetric change induces the unexpected cavity flow at the deep section of the pile. It leads to the soil rigidity affecting the profile distribution of the bearing capacity, although it is not true for a real undrained analysis. Finally, a centrifuge test is analyzed by the upper-bound method to further testify the rationality of the new failure mechanism.

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