scholarly journals Soil-Root System Withholding Strength for River Bank Stability

2016 ◽  
Vol 77 (1) ◽  
Author(s):  
IR. PROF. DR RUSLAN HASSAN HASSAN ◽  
Ding Ibau
Keyword(s):  
Relative Strength ◽  
Shear Stresses ◽  
Strength Increase ◽  
Maximum Displacement ◽  
River Bank ◽  
Slope Stabilisation ◽  
Shearing Resistance ◽  
The Stability ◽  
Direct Shear Apparatus ◽  
Riverbank Restoration

The ability of vegetation to stabilise soils is frequently employed in slope stabilisation projects including riverbank restoration activity. Soil block samples permeated with roots of Bermuda Grass commonly used for remediation and riverbank restoration were tested in a direct shear apparatus. Shear stress results of rooted soils were compared with results of un-vegetated soil bloc—s with similar soil types. The increase of shear strength was determined by comparing shear stresses at speciic horizontal displacements. The relative strength increase at the same displacement was 27.3 kPa compared to 19.1 kPa for un-vegetated soil at a displacement of 13.3cm (Location 3). The relative strength increase at the same displacement of 13.3cm was 43.5% for Location 1 and 42.4% for Location 2. The shear stresses in most of the blocks with roots were still increasing at the end of the test (maximum displacement of about 15cm). These conservative root biomass values and the shearing resistance obtained can be used in the assessment of the stability of the existing vegetated slopes and in the design of vegetated riverbanks.

scholarly journals Review on Lateral Stability of Piled Riverine Structures in the Estuaries of Sarawak

2018 ◽  
Vol 7 (3.18) ◽  
pp. 21
Author(s):  
Lee Lin Jye ◽  
Shenbaga R. Kaniraj ◽  
Siti Noor Linda bt Taib ◽  
Fauzan Bin Sahdi
Keyword(s):  
Soft Soil ◽  
Natural State ◽  
Soil Conditions ◽  
Silty Clay ◽  
River Bank ◽  
Soil Movement ◽  
Geotechnical Problem ◽  
Construction Activity ◽  
Lateral Soil Movement ◽  
The Stability

Soft soil conditions with very soft and deep silty clay have constantly endangered the stability of the riverine and estuarine structures in Sarawak. There have been many failures of jetties, wharves and bridges in Sarawak. In many cases of failures, the piles were not designed to resist the lateral movement, unless they were included to stabilize unstable slopes or potential landslides. This practice may be due to reasons such as erroneously judging the river bank as stable in slope stability analysis or simply due to the inexperience of designers. Also, when the river bank approaches the limiting stability in its natural state any construction activity on the river bank could result in lateral soil movement. This paper highlights this important geotechnical problem in Sarawak. Then it presents the details of a few failures of estuarine structures. A review of situations causing lateral loading of piles is then presented. The results of the in-soil and in-pile displacement measurements are shown in this paper and it is found that the computation made to compare between field and 3D modeling is agreeable.  

scholarly journals Safety Evaluation of Underground Caverns Based on Monte Carlo Method

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Qifeng Guo ◽  
Zhihong Dong ◽  
Meifeng Cai ◽  
Fenhua Ren ◽  
Jiliang Pan
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Three Dimensional ◽  
Safety Evaluation ◽  
Cumulative Distribution ◽  
Three Dimensional Model ◽  
Maximum Displacement ◽  
The Monte Carlo Method ◽  
Underground Caverns ◽  
The Stability

In order to study the influence of joint fissures and rock parameters with random characteristics on the safety of underground caverns, several parameters affecting the stability of surrounding rock of underground caverns are selected. According to the Monte Carlo method, random numbers satisfying normal distribution characteristics are established. A three-dimensional model of underground caverns with random characteristics is established by discontinuous analysis software 3DEC and excavation simulations are carried out. The maximum displacement at the numerical monitoring points of arch and floor is the safety evaluation index of the cavern. The probability distribution and cumulative distribution function of the displacement at the top arch and floor are obtained, and the safety of a project is evaluated.

Development of a Three-Dimensional Iterative Methodology Using a Commercial CFD Code for Flow Scouring Around Bridge Piers

2012 ◽  
Author(s):  
Phani Ganesh Elapolu ◽  
Pradip Majumdar ◽  
Steven A. Lottes ◽  
Milivoje Kostic
Keyword(s):  
Shear Stress ◽  
Three Dimensional ◽  
Critical Shear Stress ◽  
Shear Stresses ◽  
Computational Domain ◽  
Time Step ◽  
Mesh Morphing ◽  
River Bed ◽  
Scour Hole ◽  
The Stability

One of the major concerns affecting the safety of bridges with foundation supports in river-beds is the scouring of river-bed material from bridge supports during floods. Scour is the engineering term for the erosion caused by water around bridge elements such as piers, monopiles, or abutments. Scour holes around a monopile can jeopardize the stability of the whole structure and will require deeper piling or local armoring of the river-bed. About 500,000 bridges in the National Bridge Registry are over waterways. Many of these are considered as vulnerable to scour, about five percent are classified as scour critical, and over the last 30 years bridge failures caused by foundation scour have averaged about one every two weeks. Therefore it is of great importance to predict the correct scour development for a given bridge and flood conditions. Apart from saving time and money, integrity of bridges are important in ensuring public safety. Recent advances in computing boundary motion in combination with mesh morphing to maintain mesh quality in computational fluid dynamic analysis can be applied to predict the scour hole development, analyze the local scour phenomenon, and predict the scour hole shape and size around a pier. The main objective of the present study was to develop and implement a three dimensional iterative procedure to predict the scour hole formation around a cylindrical pier using the mesh morphing capabilities in the STARCCM+ commercial CFD code. A computational methodology has been developed using Python and Java Macros and implemented using a Bash script on a LINUX high performance computer cluster. An implicit unsteady approach was used to obtain the bed shear stresses. The mesh was iteratively deformed towards the equilibrium scour position based on the excess shear stress above the critical shear stress (supercritical shear stress). The model solves the flow field using Reynolds Averaged Navier-Stokes (RANS) equations, and the standard k–ε turbulence model. The iterative process involves stretching (morphing) a meshed domain after every time step, away from the bottom where scouring flow parameters are supercritical, and remeshing the relevant computational domain after a certain number of time steps when the morphed mesh compromises the stability of further simulation. The simulation model was validated by comparing results with limited experimental data available in the literature.

scholarly journals Relationship between river bank stability and hydrological processes using in situ measurement data

2019 ◽  
Vol 62 (1) ◽  
pp. 83-99 ◽  
Author(s):  
Gyula Mentes
Keyword(s):  
Measurement Data ◽  
Early Warning Systems ◽  
Bank Stability ◽  
River Bank ◽  
River Danube ◽  
Water Level Variations ◽  
Stable Part ◽  
The Stability ◽  
High Bank ◽  
River Banks

Many river banks throughout the world are prone to landslides; therefore, serious efforts are made to develop landslide early warning systems. This study presents a method by which the stability changes of the river banks can be continuously monitored; necessary measures can be taken in time to reduce the damage. The method was tested in Dunaszekcső (Hungary), where the high loess bank of the River Danube has been intensively moving since 2007. The tilts of the high bank were measured by two borehole tiltmeters. The connection between tilt values and the river- and groundwater-level variations was investigated by multivariable and moving window regression analyses on the basis of a 6-year-long observation from 2011 to 2016. The results show that increasing regression coefficients mean decreasing stability of the high river bank, so the developed method can be used for continuous supervision of the high bank stability. The method is also suitable for studying the causes of motion processes. Investigations showed clearly that the effect of groundwater table variations is two orders of magnitude higher than the water-level variations of the River Danube. In addition to the erosion of the river, various small tilts of the stable and unstable parts also contribute to the arising of new cracks in the stable part, decreasing its width.

Stability Analysis of Shear Deformable Trapezoidal Composite Plates

2019 ◽  
Vol 19 (08) ◽  
pp. 1971004 ◽  
Author(s):  
Amit Kumar ◽  
M. K. Singha ◽  
Vikrant Tiwari
Keyword(s):  
Numerical Technique ◽  
Composite Plates ◽  
Numerical Results ◽  
Shear Stresses ◽  
Quadrilateral Element ◽  
Buckling Resistance ◽  
Edge Based ◽  
The Stability ◽  
Shear Deformable ◽  
Transverse Shear Strains

The stability characteristics of shear deformable trapezoidal composite plates are studied here. Thestrain smoothing technique is employed to approximate the membrane strains and curvatures of the edge-based smoothing cells. The transverse shear strains within the Reissner–Mindlin quadrilateral element are obtained using the edge-consistent interpolation approach. At the beginning, the performance of the present numerical technique is examined for the buckling analysis of trapezoidal panels under in-plane compressive or shear stresses. Thereafter, new results on the buckling and postbuckling behaviors of trapezoidal composite plates are presented, for which comparable numerical results are rare in the literature. Representative numerical results are presented to highlight the interaction between the higher pre-buckling stresses and increased stiffness near the shorter edge with fiber orientation and loading direction on the buckling resistance of trapezoidal panels.

Optimum Design of Engine Test Bench Based on Finite Element Analysis

2011 ◽  
Vol 338 ◽  
pp. 255-258 ◽  
Author(s):  
Shao Bo Wen
Keyword(s):  
Test Bench ◽  
Excitation Frequency ◽  
Three Dimensional ◽  
Natural Vibration Frequency ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Vehicle Engine ◽  
Stress And Deformation ◽  
The Stability ◽  
Engine Excitation

A test bench of vehicle engine is designed and the three-dimensional solid model is established in UG software. Then the model is imported into ANSYS software to conduct static stress analysis, the stress and deformation distribution of test bench are obtained, referenced the results and the bracket are optimized to improve support ability, the maximum stress and the maximum displacement of test bench decreased 66.9% and 76.9%, respectively. Lastly modal analysis of test bench is performed, the chassis base is strengthen design according to the first-order mode shape, then the first natural vibration frequency is heightened 91.0%, it is far away from the engine excitation frequency range, the stability of test bench is enhanced.

Simulation Research for the Excavation Stability of IV Brittle Rock Based on Vault Settlement Effect

2014 ◽  
Vol 681 ◽  
pp. 209-213
Author(s):  
Ke Ling Liu ◽  
Long Guo
Keyword(s):  
Brittle Rock ◽  
Analysis Tool ◽  
Underground Engineering ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Simulation Research ◽  
Engineering Construction ◽  
Excavation Process ◽  
The Finite Element Analysis ◽  
The Stability

Due to the brittle rock deformation is not obvious, and the destruction process has the features of sudden and concealment, it is often neglected in the field during construction. In this paper, Brittle rock was selected as the research object. Using the vault subsidence as monitoring parameters, the excavation process was simulated in single line tunnel by the finite element analysis tool of ANSYS, we obtain the maximum displacement of brittle rock and stress variation with time. Then the subsidence effect of different buried condition were analyzed, to determine the stability period of IV Brittle surrounding rock. The research results can be used to guide the development of the monitoring standard, in underground engineering construction of the brittle rock.

scholarly journals Evaluating shear mobilization in rockfill columns used for riverbank stabilization

2009 ◽  
Vol 46 (8) ◽  
pp. 976-986 ◽  
Author(s):  
Marolo C. Alfaro ◽  
James A. Blatz ◽  
Wisam F. Abdulrazaq ◽  
Chang-Seok Kim
Keyword(s):  
Large Scale ◽  
Experimental Testing ◽  
Test Results ◽  
Lake Agassiz ◽  
Shearing Resistance ◽  
Glacial Lake Agassiz ◽  
The Stability ◽  
Rockfill Columns ◽  
The City

The major rivers within the City of Winnipeg are founded in glacial Lake Agassiz clay and silt sediments that have low shear strength. As such, riverbank instabilities are a common issue along many stretches of the rivers. The use of rockfill columns has become an increasingly utilized approach for stabilizing failing banks. Recent cases in Winnipeg have shown that movements can occur following installation of rockfill columns. Uncertainty regarding the magnitude of these movements that is required to mobilize shearing resistance in the rockfill columns has resulted in situations where the stability of riverbanks following remediation has been questioned. This has provided a need to improve our understanding about how much movement a stabilized slope must undergo before sufficient shear resistance of the rockfill column will be mobilized. The results of experimental testing conducted to assess the shear mobilization of rockfill column materials using a large-scale direct shear test apparatus are presented in this paper. The testing methodology is described along with the test results. The results show that the development of material specifications, construction, and placement methods and appropriate methods of analysis requires understanding of the stress–strain properties of the in situ soil and the rockfill material.

Design, Modeling and Finite Element Static Analysis of a New Two Axis Solar Tracker Using SolidWorks/COSMOSWorks

2013 ◽  
Vol 446-447 ◽  
pp. 738-743 ◽  
Author(s):  
Fateh Ferroudji ◽  
Toufik Ouattas ◽  
Chérif Khélifi
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Safety Factor ◽  
Equivalent Stress ◽  
Maximum Displacement ◽  
3D Cad ◽  
Optimum Position ◽  
Maximum Equivalent Stress ◽  
Solar Tracker ◽  
The Stability

This paper presents the now design, modeling and static analysis of a new two-axis solar tracker (Azimuth and Altitude). The tracker is an electro-hydraulic device that keeps photovoltaic panels in an optimum position perpendicularly to the solar radiation during daylight hours. The tracker of 24 m² panel’s size was designed using the SolidWorks 3D CAD software. The finite element method (FEM) is adopted to ensure the stability and the reliability of the tracker. COSMOSWorks was used to determine displacement, equivalent stress and safety factor of the tracker under its own weight and wind load critical, namely wind speed of 130 km/h. Simulation results show that the maximum displacement of the structure is 1.18 mm, the level of the maximum equivalent stress is 74.43 MPa and the safety factor is about 3. The tracker structure completely satisfies the design requirements.

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