Recent Advances in Seismic Design of Geosynthetically-Lined Waste Containment Facilities

Geosynthetic materials are essential elements of almost all modern landfill barrier systems. Materials such as geomembranes and geosynthetic clay liners are widely used as resistive barrier elements while geotextiles, drainage nets, and geocomposites are widely employed in modern composite barrier systems for both landfill liners and covers. The ability of these geosynthetic elements to maintain their integrity when subject to deformations due to waste settlement and seismic loading is a major uncertainty with respect to the performance of modern landfills. Over past years, advances have been made in understanding of material behavior under cyclic loading, modeling of modern landfill response to strong ground shaking, and interpretation of the analysis results. This paper presents, by reference, results of relevant recent research including advances in evaluation of dynamic material properties of municipal solid waste (MSW) and special wastes, dynamic testing of barrier system interfaces, understanding of decoupled and fully coupled response analysis, and advances in constitutive and numerical modeling relevant to better modeling of seismic response of modern landfills. Based upon the synthesis of this information, it is concluded that the commonly used decoupled approach is reasonably conservative and can be used for seismic design of modern waste containment facilities until fully coupled approach and associated evaluation and modeling of interface parameters evolve to be usable from both the practical and economic points of view

Nonlinear Time-Domain Analysis of a Sliding Block on a Plane

A time domain finite difference numerical model of a sliding rigid block on a plane is developed using a simple elastic-perfectly plas-tic Mohr-Coulomb interface model. The model is shown to accurately predict the slip-stick and slip-slip behavior deduced from an analytical solution for behavior of a sliding block on a horizontal plane and the results of physical model tests of a block on both hori-zontal and inclined planes subject to harmonic and non-uniform excitation provided the appropriate interface strength is employed. Back analyses of the physical model tests show that for some geosynthetic interfaces, the interface shear strength depends upon the velocity of sliding. The numerical model developed herein provides a basis for rigorous evaluation of several important problems in geotechnical earthquake engineering, including the cumulative permanent seismic deformation of landfills, embankments, slopes, and retaining walls and the stresses induced by seismic loading in geosynthetic elements of landfill liner and cover systems

Seismic Design of Landfills for NE United States

Northeastern U.S. seismicity is briefly discussed and design earthquake is established for landfill projects in accordance with current federal regulations. Methods previously developed for embankment dams are reviewed relative to the seismic stability evaluation of solid waste landfills. Charts were developed to expedite bottom liner and cover system selection while meeting particular seismic design requirements

Development of water surface mobile garbage collector robot

This paper presents a prototype of Water Surface Mobile Garbage Collector Robot built in motivation to educate the people to love and monitor the health of our rivers by collecting the trash themselves using mobile robot. The garbage collector is designed aimed for the cleaning of small-scale lakes, narrow rivers, and drains in Malaysia. The navigation of the robot is controlled using wireless Bluetooth communication from a smartphone application. The performance of the water garbage collector in terms of manoeuvring control efficiency and garbage collection load capacity was tested and evaluated. Based on the experimental results from a swimming pool, it can operate within a 4-metre range and collect 192 grams of small to medium sized recyclable garbage such as food packages, water bottles, and plastics in 10 seconds. It managed to float and navigate on the Panchor River within Bluetooth network range. A strong, lightweight and waterproof material is recommended for use for this water garbage collector. A proximity sensor or image processing technique for detecting garbage on the water surface may be studied and included in the future to enable a fully autonomous manoeuvring control system

Validation of a Numerical Model for Design of Geomembranes Subject to Extreme Loads

abstract: A numerical model for design of the geomembrane elements of waste containment systems has been validated by laboratory testing. Due to the absence of any instrumented case histories of seismic performance of geomembrane liner systems, a large scale centrifuge test of a model geomembrane-lined landfill subject to seismic loading was conducted at the University of California at Davis Centrifuge Test facility as part of National Science Foundation Network for Earthquake the Engineering Simulation Research (NEESR) program. Data collected in the large scale centrifuge test included waste settlement, liner strains and earthquake accelerations at various locations throughout the model. This data on landfill and liner seismic performance has been supplemented with additional laboratory and small scale centrifuge tests to determine the parameters required for the numerical model, including strength and stiffness of the model materials, interface shear strengths, and interface stiffness. The numerical model explicitly assesses the forces and strains in the geomembrane elements of a containment system to subject to both static and seismic loads the computer code FLACTM, a finite difference program for non-linear analysis of continua. The model employs a beam element with zero moment of inertia and with interface elements on both sides to model to represent the geomembrane elements in the liner system. The model also includes non-linear constitutive models for the stress-strain behavior of geomembrane beam elements and an elastic-perfectly plastic model for the load-displacement behavior of the beam interfaces. Parametric studies are conducted with the validated numerical model to develop recommendations for landfill design, construction, and construction quality assurance.Dissertation/ThesisDoctoral Dissertation Civil and Environmental Engineering 201

Seismic displacement analysis of homogeneous slopes: a review of existing simplified methods with reference to Italian seismicity.

The simplified displacement-based procedures for seismic slope stability represent a good-working balance between simplicity and reliability, since both slope ductility (i.e. the capacity of sustain permanent displacements) and deformability (basically affecting the asynchronous slope motion) are accounted for. In this paper the procedure proposed by Bray & Rathje (1998) is reviewed with particular reference to Italian seismicity on a set of subsoil models, representative of the different soil classes specified by Italian and European codes. The relationship expressing the decrease of the equivalent acceleration with increasing earthquake/soil frequency ratio is then obtained by means of dynamic 1D site response analyses. Statistical correlations between calculated Newmark displacements, significant ground motion parameters and the ratio of seismic load resistance to peak demand are then derived and compared to similar relationships proposed in literature

Shaking Table Experiment of a Model Slope Subjected to a Pair of Repeated Ground Motions

This paper describes the third of a series of six shaking table experiments conducted as part of ongoing research to evaluate the accuracy and applicability of the Newmark (1965) procedure for computing seismically induced deformation in slopes. A cohesive model slope was shaken by two identical test motions in succession, mimicking a situation that commonly occurs when a preexisting landslide is subjected to strong earthquake shaking. Back analyses of the tests showed that the Newmark (1965) formulation provided moderately accurate estimates of the measured permanent deformations (within 40% to 85% of the maximum measured displacement). The accuracy of the Newmark (1965) formulation was greatest when displacement-dependent degrading yield acceleration was used to model the soil’s transition from peak to residual shear strength. The Newmark analyses were most reliable for the second test that experienced relatively large deformations, and thus where the sliding resistance was controlled by post-peak to residual strength

Performance of Landfills Under Seismic Loading

The record of performance of landfills in earthquakes is excellent. However, the advent of geosynthetic liner and cover systems has increased the susceptibility of modern landfills to seismically-induced instability and deformations. Analyses used to assess the performance of landfills in earthquakes include site response, limit equilibrium stability, and Newmark deformation analyses. Well documented case histories of the behavior of landfills subject to seismic loading are necessary to improve knowledge of the parameters required for these analyses and thereby enhance the reliability of seismic performance evaluations for landfills