scholarly journals Study of Clayey Soils with Nonwoven Geotextiles as Liners in Landfill Stabilization

2021 ◽  
Vol 9 (VI) ◽  
pp. 1239-1241
Author(s):  
Sreeteja Bala Padmaja
Keyword(s):  
Soil Stabilization ◽  
Ground Level ◽  
Coastal Engineering ◽  
Clayey Soils ◽  
Load Bearing Capacity ◽  
Angle Of Internal Friction ◽  
Shearing Resistance ◽  
Wide Range ◽  
Bank Protection ◽  
Plastic Membrane

Landfills are highly complex, well-engineered series of cells in or above the ground level. Soil stabilization is the alteration of soils to enhance their physical properties. Landfill stabilization increase the shear strength of soil thus improving the load bearing capacity. Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect or drain. All have a wide range of applications and are currently used to advantage in many civil engineering applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, bank protection and coastal engineering. Typically made from polyester, they are classified into woven, needle punched, heat bonded. nonwoven geotextiles are manufactured by bonding materials together made of synthetics and used in separation applications. Non-woven geotextiles have more gaps of plastic membrane and right choice where pooling water is major concern i.e. drainage systems. In this present study, different geotextiles gives varying advantages. The permeability of the soil can be reduced to desired coefficient and also increased based on the type of geotextile used. The angle of shearing resistance (angle of internal friction) would be lower than that of the unreinforced soils. The performance of the geotextiles depends upon the index properties of the soil.

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.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

scholarly journals Design and Evaluation of Sensor Housing for Boundary Layer Profiling Using Multirotors

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2481 ◽  
Author(s):  
Ashraful Islam ◽  
Adam L. Houston ◽  
Ajay Shankar ◽  
Carrick Detweiler
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Ground Level ◽  
Radiation Shielding ◽  
Unmanned Aerial Systems ◽  
Heat Sources ◽  
Wide Range ◽  
Artificial Heat ◽  
Aerial Systems ◽  
Airborne Sensors

Traditional configurations for mounting Temperature–Humidity (TH) sensors on multirotor Unmanned Aerial Systems (UASs) often suffer from insufficient radiation shielding, exposure to mixed and turbulent air from propellers, and inconsistent aspiration while situated in the wake of the UAS. Descent profiles using traditional methods are unreliable (when compared to an ascent profile) due to the turbulent mixing of air by the UAS while descending into that flow field. Consequently, atmospheric boundary layer profiles that rely on such configurations are bias-prone and unreliable in certain flight patterns (such as descent). This article describes and evaluates a novel sensor housing designed to shield airborne sensors from artificial heat sources and artificial wet-bulbing while pulling air from outside the rotor wash influence. The housing is mounted above the propellers to exploit the rotor-induced pressure deficits that passively induce a high-speed laminar airflow to aspirate the sensor consistently. Our design is modular, accommodates a variety of other sensors, and would be compatible with a wide range of commercially available multirotors. Extensive flight tests conducted at altitudes up to 500 m Above Ground Level (AGL) show that the housing facilitates reliable measurements of the boundary layer phenomena and is invariant in orientation to the ambient wind, even at high vertical/horizontal speeds (up to 5 m/s) for the UAS. A low standard deviation of errors shows a good agreement between the ascent and descent profiles and proves our unique design is reliable for various UAS missions.

scholarly journals Predicting the Saturated Hydraulic Conductivity of Clayey Soils and Clayey or Silty Sands

Geosciences ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 393
Author(s):  
Stefania Bilardi ◽  
Domenico Ielo ◽  
Nicola Moraci
Keyword(s):  
Hydraulic Conductivity ◽  
Clay Content ◽  
Limited Range ◽  
Saturated Hydraulic Conductivity ◽  
Reliable Estimate ◽  
Clayey Soils ◽  
Geotechnical Parameters ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Different Soils

Predictive models able to provide a reliable estimate of hydraulic conductivity can be useful in various geotechnical applications. Since most of the existing predictive methods for saturated hydraulic conductivity estimation are valid only for a limited range of soils or can be applied under certain restrictive conditions, a new method applicable to clayey soils and clayey or silty sands having a wide range of values of soil index properties is proposed in this study. For this purpose, 329 saturated hydraulic conductivity values, obtained by laboratory tests carried out on different soils, were collected in a database and used to develop five equations using a multiple regression approach. Each equation correlates the hydraulic conductivity with one or more geotechnical parameters. An equation was developed that predicts, within an order of magnitude, the saturated hydraulic conductivity in the range from 1.2 × 10−11 to 3.9 × 10−6 m/s, based on simple geotechnical parameters (i.e., clay content, void ratio, plastic limit, and silt content).

Design, Development and Characterization of a Wrap Spring Clutch/Brake Mechanism As a Knee Joint for an Assistive Exoskeleton

2020 ◽  
Author(s):  
Vishnu Aishwaryan Subra Mani ◽  
Nathaniel Goldfarb ◽  
Gregory S. Fischer
Keyword(s):  
Knee Joint ◽  
Ground Level ◽  
Design Approach ◽  
Stress Tests ◽  
Design Development ◽  
Research Activities ◽  
Wide Range ◽  
And Performance ◽  
Spring Clutch ◽  
The Right

Abstract Over the past decade, wearable robotics and exoskeletons have been gaining recognition in the field of medical, assistive and augmentative robotics and have led to numerous new innovative mechanisms and designs. Due to fast-paced research activities, the critical importance and performance of established mechanisms such as wrap spring clutch/brake, Wafer Disc Brakes have been overlooked or used ineffectively. This paper describes a practical design approach that will enable the designer to choose a mechanism based on the application of the device, which will promote overall growth in current technology. The Legged Anthropomorphic Robotic Rehabilitation Exoskeleton (LARRE) project used this approach to design, manufacture, and test the knee joint for ground-level walking. This paper provides the reasoning behind the selection of wrap spring clutch, its evaluation, and testing standards as the knee joint. A thorough literature review was conducted to understand the current state of the art. This project collected a rich set of biomechanical data to ensure that the mechanism will produce the right moments and range of motions during walking. To ensure that our mechanism meets the requirements, the mechanism was put through a wide range of stress tests. The paper establishes a methodology to choose a mechanism for an exoskeleton’s joint based on the desired requirements. The outcome of this paper is an analytical based design approach that can be used by other researchers to impart additional traits and weights, which will aid in the development of exoskeleton design.

Formulation of Seismic Passive Resistance of Retaining Wall Backfilled with c-F Soil

2012 ◽  
Vol 3 (2) ◽  
pp. 15-24 ◽  
Author(s):  
Sima Ghosh
Keyword(s):  
Retaining Wall ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Friction Angle ◽  
Wall Friction ◽  
Unit Weight ◽  
Passive Resistance ◽  
Angle Of Internal Friction ◽  
Variation Of Parameters ◽  
Wide Range

Knowledge of passive resistance is extremely important and it is the basic data required for the design of geotechnical structures like the retaining wall moving towards the backfill, the foundations, the anchors etc. An attempt is made to develop a formulation for the evolution of seismic passive resistance of a retaining wall supporting c-F backfill using pseudo-static method. Considering a planar rupture surface, the formulation is developed in such a way so that a single critical wedge surface is generated. The variation of seismic passive earth pressure coefficient are studied for wide range of variation of parameters like angle of internal friction, angle of wall friction, cohesion, adhesion, surcharge, unit weight of the backfill material, height and seismic coefficients.

Variation of Initial Soil Suction with Compaction Conditions for Clayey Soils

2012 ◽  
Vol 28 (3) ◽  
pp. 431-437 ◽  
Author(s):  
S.-R. Yang ◽  
H.-D. Lin ◽  
W.-H. Huang
Keyword(s):  
Water Content ◽  
Clay Fraction ◽  
Degree Of Saturation ◽  
Soil Suction ◽  
Clayey Soils ◽  
Test Results ◽  
Wide Range ◽  
Initial Soil ◽  
Compaction Energy ◽  
The Relationship

AbstractIn this study, the initial soil suction of as-compacted clayey soils was evaluated for various compaction conditions, covering a wide range of compaction energy and molding water content. The soil specimens were prepared by impact compaction under three levels of compaction energy. The filter paper method was used to measure the initial soil suction of as-compacted specimens. Test results indicate that the relationship between the soil suction and the molding water content is bilinear under three different compaction energies. However, the effect of compaction energy on soil suction is different for the soils with different amounts of clay fraction and is elucidated by the macro soil properties. The change of soil suction due to different compaction energies can be predicted by the void ratio and the degree of saturation.

scholarly journals Experimentation on Stabilization of Problematic Clays by using Lime and Asphalt Emulsion

2019 ◽  
Vol 8 (12S) ◽  
pp. 967-973
Keyword(s):  
Structural Properties ◽  
Soil Stabilization ◽  
Expansive Soil ◽  
Point Of View ◽  
Asphalt Emulsion ◽  
Load Bearing Capacity ◽  
Stabilization Process ◽  
Subgrade Soil ◽  
Testing Techniques ◽  
Roadway Construction

Soil stabilization with liquid asphalt is considered as a sustainable step towards roadway construction on problematic subgrade soil, there are no requirements to import good quality materials or to implement energy consumption, but to mix the readily available soil with liquid asphalt through the cold mix technique. In this work, expansive soil obtained from Manali, Chennai was mixed with asphalt emulsion, lime, and combinations of lime and asphalt emulsion (combined stabilization) and tested in the laboratory for California bearing ratio in dry and soaked conditions. Field trial sections have been prepared with the same combinations and subjected to plate bearing test. The influence of combined stabilization on the structural properties in terms of load bearing capacity and deformation under both testing techniques have been monitored and analyzed. It was concluded that 17% of asphalt emulsion and 6% lime can furnish a suitable combined stabilization process from the structural properties requirements point of view.

Urban climate zone classification using convolutional neural network and ground-level images

2019 ◽  
Vol 43 (3) ◽  
pp. 410-424 ◽  
Author(s):  
Guang Xu ◽  
Xuan Zhu ◽  
Nigel Tapper ◽  
Benjamin Bechtel
Keyword(s):  
Urban Climate ◽  
Three Dimensional ◽  
Ground Level ◽  
Critical Issue ◽  
Urban Environments ◽  
Bare Rock ◽  
Climate Zone ◽  
Local Climate ◽  
Climate Risks ◽  
Wide Range

Urban climate risks have a wide range of impacts on the health of more than 50% of the world’s population, which is a critical issue relating to climate change. To support urban climate study and categorise different urban environments and their atmospheric impacts in a consistent way, the Local Climate Zone (LCZ) classification scheme has been developed. The World Urban Database and Access Portal Tools project aims to map the LCZ of cities across the globe. However, previous classification approaches based on satellite images have limitations regarding the characterisation of three-dimensional features such as building heights. This study aims to apply convolutional neural networks to classify LCZ types based on ground-level images, which can provide more detail of the urban environments. Validation results have shown an overall accuracy of 69.6%. The new method outperformed previous satellite-based studies for classifying the LCZ types Compact Mid-rise, Sparsely Built, Heavy Industry, and Bare Rock or Paved.

scholarly journals Finite element modeling of lateral pipeline–soil interactions in dense sand

2016 ◽  
Vol 53 (3) ◽  
pp. 490-504 ◽  
Author(s):  
Kshama Roy ◽  
Bipul Hawlader ◽  
Shawn Kenny ◽  
Ian Moore
Keyword(s):  
Finite Element ◽  
Internal Friction ◽  
Plane Strain ◽  
Smooth Transition ◽  
Burial Depth ◽  
Angle Of Internal Friction ◽  
Dense Sand ◽  
Dilation Angle ◽  
Wide Range ◽  
Force Displacement

Finite element (FE) analyses of pipeline–soil interaction for pipelines buried in dense sand subjected to lateral ground displacements are presented in this paper. Analysis is performed — using the Arbitrary Lagrangian–Eulerian (ALE) method available in Abaqus/Explicit FE software — in the plane strain condition using the Mohr–Coulomb (MC) and modified Mohr–Coulomb (MMC) models. The MMC model considers a number of important features and properties of stress–strain and volume change behaviour of dense sand including the nonlinear pre- and post-peak behaviour with a smooth transition and the variation of the angle of internal friction and dilation angle with plastic shear strain, loading conditions (triaxial or plane strain), density, and mean effective stress. Comparing FE and experimental results, it is shown that the MMC model can better simulate the force–displacement response for a wide range of lateral displacements of the pipe for different burial depths, although the peak force on the pipe could be matched using the MC model. Examining the progressive development of zones of large inelastic shear deformation (shear bands), it is shown that the mobilized angle of internal friction and dilation angle vary along the length of the shear band; however, constant values are used in the MC model. A comprehensive parametric study is also performed to investigate the effects of pipeline diameter, burial depth, and soil properties. Many important aspects in the force–displacement curves and failure mechanisms are explained using the present FE analyses.

Sign in / Sign up

Export Citation Format

Share Document