Estimating Dynamic Properties from Static Tests

The applicability of various types of constitutive models to estimating dynamic material properties for soils from the results of static shear tests is briefly reviewed. The primary obstacle to making such predictions is the limiting resolution of conventional static tests. A simple procedure using empirical relationships to interpolate beyond the limit of the static shear tests is suggested for use in preliminary analysis and in cases where cyclic test data is not available

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

Effective Stress Analyses of Seismic Stability

The factors involved in performing effective stress analysis of seismic stability problems are examined. The advantages of using a stochastic model for pore pressure generation are discussed. A simplified analysis of a hypothetical case is outlined to illustrate the factors involved in performing effective stress stability analysis

Solid Waste Landfill Performance During the 1994 Northridge Earthquake

The performance of 22landfills in the Los Angeles area during the January 17, 1994 Northridge earthquake has been investigated. Observations of damage at these landfills indicate that the overall performance of solid waste landfills was encouraging. None of the surveyed landfills showed any signs of major damage. However, one geosynthetic-lined landfill experienced two tears in the geomembrane liner. Most landfills within 30 km of the zone of energy release experienced some form of cracking in the soil cover. Beyond approximately 40 km from the zone of energy release, little to no damage was observed

A multi-phase biogeochemical model for mitigating earthquake-induced liquefaction via microbially induced desaturation and calcium carbonate precipitation

A next-generation biogeochemical model was developed to explore the impact of the native water source on microbially induced desaturation and precipitation (MIDP) via denitrification. MIDP is a non-disruptive, nature-based ground improvement technique that offers the promise of cost-effective mitigation of earthquake-induced soil liquefaction under and adjacent to existing structures. MIDP leverages native soil bacteria to reduce the potential for liquefaction triggering in the short term through biogenic gas generation (treatment completed within hours to days) and over the longer term through calcium carbonate precipitation (treatment completed in weeks to months). This next-generation biogeochemical model expands earlier modeling to consider multi-phase speciation, bacterial competition, inhibition, and precipitation. The biogeochemical model was used to explore the impact of varying treatment recipes on MIDP products and by-products in a natural seawater environment. The case study presented herein demonstrates the importance of optimizing treatment recipes to minimize unwanted by-products (e.g., H2S production) or incomplete denitrification (e.g., nitrate and nitrite accumulation).</p