Seismic response of landfill

Last updated February 21, 2019

Solid waste landfills can be affected by seismic activity. The tension in a landfill liner rises significantly during an earthquake, and can lead to stretching or tearing of the material. [1] The top of the landfill may crack, and methane collection systems can be moved relative to the cover. [2]

Landfill site for the disposal of waste materials by burial

A landfill site is a site for the disposal of waste materials by burial. It is the oldest form of waste treatment. Historically, landfills have been the most common method of organized waste disposal and remain so in many places around the world.

A landfill liner, or composite liner, is intended to be a low permeable barrier, which is laid down under engineered landfill sites. Until it deteriorates, the liner retards migration of leachate, and its toxic constituents, into underlying aquifers or nearby rivers, causing spoliation of the local water.

An earthquake is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities. The seismicity, or seismic activity, of an area is the frequency, type and size of earthquakes experienced over a period of time. The word tremor is also used for non-earthquake seismic rumbling.

Increasing the depth of a waste column typically leads to a decrease in the ground acceleration felt at the surface of that landfill during an earthquake. [3] The weight of waste is important in the analysis of landfill liner puncture and pipe crushing during an earthquake. [4] Unstable rock under landfills such as limestone may yield during an earthquake, leading to a partial collapse of the fill. [5] A major concern in this case would be the potential contamination of water sources that may be located below the landfill. [5]

Modeling

In a pseudostatic slope stability analysis, the earthquake is modeled as a constant horizontal force. The fact that the earthquake force is modeled as a constant force acting in one direction, represents this model's major limitation. [3] In a Newmark permanent deformation mathematical analysis, movement of a landfill occurs when a driving force on the landfill is greater than its resisting force. [3] A shaking table laboratory test works to explore the strength characteristics at interfaces between different components of the landfill. Of primary concern is the contact between soil and landfill liner, as this is usually considered to be a weak point in the system. [4] A dynamic centrifuge test works to model the landfill in a scaled-down form. Typically in this approach, a small simplified landfill is constructed in a test box. During this testing, earthquake loading is simulated on the sample landfill. A major application of this type of testing is to observe the behavior of landfill liners during ground shaking.

Slope stability analysis is performed to assess the safe design of a human-made or natural slopes and the equilibrium conditions. Slope stability is the resistance of inclined surface to failure by sliding or collapsing. The main objectives of slope stability analysis are finding endangered areas, investigation of potential failure mechanisms, determination of the slope sensitivity to different triggering mechanisms, designing of optimal slopes with regard to safety, reliability and economics, designing possible remedial measures, e.g. barriers and stabilization.

The uniqueness of many landfills makes it difficult to apply test results from one site to another. Measuring properties of landfills such as waste unit weight could lead to health concerns, as the handling of waste could be dangerous. Accessing this waste would likely involve damaging the cover liner, which could compromise the ability of the system to function properly. Landfills are systems which change over time, so periodic evaluations may be necessary.^{[ citation needed ]}

Related Research Articles

Geotechnical engineering branch of civil engineering concerned with the engineering behavior of earth materials

Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. Geotechnical engineering is important in civil engineering, but also has applications in military, mining, petroleum and other engineering disciplines that are concerned with construction occurring on the surface or within the ground. Geotechnical engineering uses principles of soil mechanics and rock mechanics to investigate subsurface conditions and materials; determine the relevant physical/mechanical and chemical properties of these materials; evaluate stability of natural slopes and man-made soil deposits; assess risks posed by site conditions; design earthworks and structure foundations; and monitor site conditions, earthwork and foundation construction.

Soil liquefaction occurs when a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in stress condition, in which material that is ordinarily a solid behaves like a liquid.

Engineering geology is the application of the geology to engineering study for the purpose of assuring that the geological factors regarding the location, design, construction, operation and maintenance of engineering works are recognized and accounted for. Engineering geologists provide geological and geotechnical recommendations, analysis, and design associated with human development and various types of structures. The realm of the engineering geologist is essentially in the area of earth-structure interactions, or investigation of how the earth or earth processes impact human made structures and human activities.

Geosynthetics are synthetic products used to stabilize terrain. They are generally polymeric products used to solve civil engineering problems. This includes eight main product categories: geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells and geocomposites. The polymeric nature of the products makes them suitable for use in the ground where high levels of durability are required. They can also be used in exposed applications. Geosynthetics are available in a wide range of forms and materials. These products have a wide range of applications and are currently used in many civil, geotechnical, transportation, geoenvironmental, hydraulic, and private development applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, erosion control, sediment control, landfill liners, landfill covers, mining, aquaculture and agriculture.

Earthquake engineering is an interdisciplinary branch of engineering that designs and analyzes structures, such as buildings and bridges, with earthquakes in mind. Its overall goal is to make such structures more resistant to earthquakes. An earthquake engineer aims to construct structures that will not be damaged in minor shaking and will avoid serious damage or collapse in a major earthquake. Earthquake engineering is the scientific field concerned with protecting society, the natural environment, and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels. Traditionally, it has been narrowly defined as the study of the behavior of structures and geo-structures subject to seismic loading; it is considered as a subset of structural engineering, geotechnical engineering, mechanical engineering, chemical engineering, applied physics, etc. However, the tremendous costs experienced in recent earthquakes have led to an expansion of its scope to encompass disciplines from the wider field of civil engineering, mechanical engineering and from the social sciences, especially sociology, political science, economics and finance.

A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid migration in a human-made project, structure, or system. Geomembranes are made from relatively thin continuous polymeric sheets, but they can also be made from the impregnation of geotextiles with asphalt, elastomer or polymer sprays, or as multilayered bitumen geocomposites. Continuous polymer sheet geomembranes are, by far, the most common.

Geosynthetic clay liners (GCLs) are factory manufactured hydraulic barriers consisting of a layer of bentonite or other very low-permeability material supported by geotextiles and/or geomembranes, mechanically held together by needling, stitching, or chemical adhesives. Due to environmental laws, any seepage from landfills must be collected and properly disposed off, otherwise contamination of the surrounding ground water could cause major environmental and/or ecological problems. The lower the hydraulic conductivity the more effective the GCL will be at retaining seepage inside of the landfill. Bentonite composed predominantly (>70%) of montmorillonite or other expansive clays, are preferred and most commonly used in GCLs. A general GCL construction would consist of two layers of geosynthetics stitched together enclosing a layer of natural or processed sodium bentonite. Typically, woven and/or non-woven textile geosynthetics are used, however polyethylene or geomembrane layers or geogrid geotextiles materials have also been incorporated into the design or in place of a textile layer to increase strength. GCLs are produced by several large companies in North America, Europe, and Asia. The United States Environmental Protection Agency currently regulates landfill construction and design in the US through several legislations.

The George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) was created by the National Science Foundation (NSF) to improve infrastructure design and construction practices to prevent or minimize damage during an earthquake or tsunami. Its headquarters were at Purdue University in West Lafayette, Indiana as part of cooperative agreement #CMMI-0927178, and it ran from 2009 till 2014. The mission of NEES is to accelerate improvements in seismic design and performance by serving as a collaboratory for discovery and innovation.

UTEXAS is a slope stability analysis program written by Stephen G. Wright of the University of Texas at Austin. The program is used in the field of civil engineering to analyze levees, earth dams, natural slopes, and anywhere there is concern for mass wasting. UTEXAS finds the factor of safety for the slope and the critical failure surface. Recently the software was used to help determine the reasons behind the failure of I-walls during Hurricane Katrina.

Earthquake-resistant structures are structures designed to protect buildings from earthquakes. While no structure can be entirely immune to damage from earthquakes, the goal of earthquake-resistant construction is to erect structures that fare better during seismic activity than their conventional counterparts. According to building codes, earthquake-resistant structures are intended to withstand the largest earthquake of a certain probability that is likely to occur at their location.This means the loss of life should be minimized by preventing collapse of the buildings for rare earthquakes while the loss of the functionality should be limited for more frequent ones.

SVSLOPE is a slope stability analysis program developed by SoilVision Systems Ltd.. The software is designed to analyze slopes using both the classic "method of slices" as well as newer stress-based methods. The program is used in the field of civil engineering to analyze levees, earth dams, natural slopes, tailings dams, heap leach piles, waste rock piles, and anywhere there is concern for mass wasting. SVSLOPE finds the factor of safety or the probability of failure for the slope. The software makes use of advanced searching methods to determine the critical failure surface.

Final cover is a multilayered system of various materials which are primarily used to reduce the amount of storm water that will enter a landfill after closing. Proper final cover systems will also minimize the surface water on the liner system, resist erosion due to wind or runoff, control the migrations of landfill gases, and improve aesthetics.

Sarada Kanta Sarma is a geotechnical engineer, emeritus reader of engineering seismology and senior research investigator at Imperial College London. He has developed a method of seismic slope stability analysis which is named after him, the Sarma method.

The Newmark's sliding block analysis method is an engineering that calculates permanent displacements of soil slopes during seismic loading. Newmark analysis does not calculate actual displacement, but rather is an index value that can be used to provide an indication of the structures likelihood of failure during a seismic event. It is also simply called Newmark's analysis or Sliding block method of slope stability analysis.

The Sarma method is a method used primarily to assess the stability of soil slopes under seismic conditions. Using appropriate assumptions the method can also be employed for static slope stability analysis. It was proposed by Sarada K. Sarma in the early 1970s as an improvement over the other conventional methods of analysis which had adopted numerous simplifying assumptions.

Geotechnical centrifuge modeling is a technique for testing physical scale models of Geotechnical Engineering systems such as natural and man-made slopes and earth retaining structures and building or bridge foundations.

Timothy D. Stark is a Professor of Geotechnical Engineering in the Department of Civil and Environmental Engineering at the University of Illinois at Urbana–Champaign since 1991. Dr. Stark teaches undergraduate and graduate courses in Foundation Engineering and Earth Structures, respectively, in the Department of Civil and Environmental Engineering at the UIUC and numerous short courses for various entities. Dr. Stark has served as a consultant and expert on a range of domestic and international projects including levees and dams, buildings, bridges, slopes, geosynthetics, seismic issues, waste containment facilities, and highways. Dr. Stark’s current research interests include: (1) Design and performance of Earth Dams, Levees, Floodwalls, Landfills, and other Earth Structures, (2) Behavior of Railroad Track Systems and Transitions, (3) Forensic Geotechnical and Foundation Engineering, (4) Static and Seismic Stability of Natural and Man-Made Slopes, (5) Performance of Compacted Structural Fills and Slopes, and (6) Behavior and Design of Waste Containment Facilities.

Ronald Kerry Rowe, FRS, FRSC, FREng is a Canadian civil engineer of Australian birth, one of the pioneers of geosynthetics.

References

↑ Thusyanthan, N.I.; Madabhushi, S.P.G.; Singh, S. (2007) "Tension in Geomembranes on Landfill slopes Under Static and Earthquake Loading - Centrifuge Study" Geotextiles and Geomembranes V. 25: 78-95.
↑ Matasovic, N.; Kavazanjian Jr., E. (2006) "Seismic Response of a Composite Landfill Cover" Journal of Geotechnical and Geoenvironmental Engineering V. 132(4): 448-455.
1 2 3 Bray, J.D.; Augello, A.J.; Leonards, G.A.; Repetto, P.C.; Byrne, R.J. (1995) "Seismic Stability Procedures for Solid-Waste Landfills" Journal of Geotechnical Engineering V. 121(2): 139-151.
1 2 Choudhury, D.;Savoikar, P. (2009) "Simplified Method to Characterize Municipal Solid Waste Properties Under Seismic Conditions" Waste Management V. 29(2):924-933.
1 2 Krinitzsky, E.L.;Hynes, M.E;Franklin, A.G (1997) "Earthquake Safety Evaluation of Sanitary Landfills" Engineering Geology V. 46(2): 143-156.

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[1] Thusyanthan, N.I.; Madabhushi, S.P.G.; Singh, S. (2007) "Tension in Geomembranes on Landfill slopes Under Static and Earthquake Loading - Centrifuge Study" Geotextiles and Geomembranes V. 25: 78-95.

[2] Matasovic, N.; Kavazanjian Jr., E. (2006) "Seismic Response of a Composite Landfill Cover" Journal of Geotechnical and Geoenvironmental Engineering V. 132(4): 448-455.

[bray-3] 1 2 3 Bray, J.D.; Augello, A.J.; Leonards, G.A.; Repetto, P.C.; Byrne, R.J. (1995) "Seismic Stability Procedures for Solid-Waste Landfills" Journal of Geotechnical Engineering V. 121(2): 139-151.

[choudhury-4] 1 2 Choudhury, D.;Savoikar, P. (2009) "Simplified Method to Characterize Municipal Solid Waste Properties Under Seismic Conditions" Waste Management V. 29(2):924-933.

[krinitzsky-5] 1 2 Krinitzsky, E.L.;Hynes, M.E;Franklin, A.G (1997) "Earthquake Safety Evaluation of Sanitary Landfills" Engineering Geology V. 46(2): 143-156.