General Report - Session 5

This General Report summarizes the papers submitted to Session 5 titled “Case Histories and Failure of Geological, Rock and Mining Engineering, including Underground Structures and Excavations, and Subsidence of Deltas, Anticipation, Characterization, Design and Construction in the Geological Complexity of Mélanges, Fault Rocks, Weathered Rocks, Boulder Colluvium, Lahars, and Similar Bimrocks (Block-in-Matrix Rocks) and Rock/Soil Mixtures.” A total of eleven papers covering the broad session themes described above were submitted. The geographic distribution of the case histories is listed in Table 1. Overall, five papers were submitted from Asia, two from Africa, two from North America, and two from Europe

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

3D electrical resistivity tomography technique for the investigation of a construction and demolition waste landfill site

We present the practical application of a 3D electrical resistivity tomography (ERT) geophysical survey conducted in order to calculate the geometrical features and general structure of a construction and demolition waste layer in an old unregulated landfill prior to redevelopment. As traditional geological/geotechnical investigations comprised of cone penetration tests (CPT) failed to provide reliable results, primarily due to the nature of the underlying waste, a geophysical investigation was commissioned and found to be very effective in providing useful and accurate information to the project’s environmental and engineering team. The ERT survey data were collected in parallel equidistant lines and were subsequently merged and inverted as a single 3D dataset. The processed data depicted clearly the interface between the resistive construction waste and the conductive undisturbed host clay layer ranging at depths between 3 and 11 m. As a result of this successful geophysical investigation the total volume of the solid waste materials was calculated to be about 32500 m3. Following the complete removal of the waste it became evident that the ERT geophysical survey results were particularly accurate. As a result, the reclamation constructor was able to carefully plan the required resources for excavating, moving and disposing of the waste. Interpreted ERT data not only defined the thickness of the debris layer and the total volume with a deviation of less than 10%, but also revealed the inner structure of the solid waste layer