GENERAL51884 - Laserfiche WebLink

Home Browse Search

Mc Jim Mattern February 1, 2007 Page 2 This report contains only preliminary conclusions from analyses since no new post-event geotechnical property information has been gathered. Field observations supporting analysis results are included by reference to the previous trip report where appropriate. Other geotechnical activities, other than modeling analyses, are being undertaken as a result of the recent landslide. As TMI's geotechnical consultant, AAI has been requested to provide technical assistance in the following activities associated with the landslide investigation: • Assess potential imminent risk to other mining areas • Finish model calibration of G-Pit • Develop monitoring data collection plan and subsequent data analysis • Technical support for regulatory issues • Assessment of long-term risk of similar event • Assessment of implications to the reserve Evaluation of a mining plan for remaining G-Pit and K-Pit reserves It is only the first three of these tasks that are addressed in this report. ANALYSIS OF G-PIT CUT FAILURE A mine-scale numerical model of the G-Pit area of the mine was developed. The modeling work was begun prior to the October 2006 event. The purpose at the time was to assess the need to reorient the Dip Pit as mining progressed westward toward the steeper dipping beds. The modeling effort was modified after the October 2006 event so that the purpose of the model was to (1) back-analyze the G-Strike Pit highwall failure of September 2005 by calibrating rock mass properties to the failure, and (2) examine possible failure mechanisms leading to the recent landslide. The model has been developed utilizing the three-dimensional (3D} FLAC'3D finite-difference programZ Average rock mass material properties are used in the analysis based on laboratory testing and field characterization of conditions. ~ The purpose of the analysis is to allow failure mechanisms to occur given realistic geometries and ground conditions. Due to the complexity of conditions, some material property assumptions made in the model were modified to better delineate local and global failure propagation. A complete description of the model is found in the G-Pit landslide analysis report; That report discusses model assumptions, methodology employed, geometry simulated, material Z Itasca Consulting Group, Inc. (2005), Fast Lagrangian Analysis of Continua in 3 Dimensions, "User's Guide," Version 3, Minneapolis, MN. ~ Agapito Associates, Inc. (2007), `G-Pit Landslide Stability Report-Task 2," prepared for Trapper Mining, Inc., In progress. Agapito Associates, Inc.