Geotechnical Characterization of Rock
Marshall Miller & Associates conducts geotechnical assessments in all types of rock and soil environments utilizing proven data collection and rock material characterization techniques. MM&A’s geotechnical team completes projects for the aggregate, coal, and hardrock mining industries, for both surface and underground mining applications, in locations throughout the United States and around the World. All geotechnical projects begin with characterization of the geologic, geotechnical, and geohydrological setting of the subject area. MM&A’s geotechnical project team completes all aspects of geotechnical projects, from planning and implementation of the data collection activities, to completion and presentation of the results. MM&A’s staff includes experienced personnel skilled in detailed core logging, underground and surface mine observations, and down-hole geophysical logging. Our staff also includes geologists and mining engineers that have completed numerous geotechnical assessments involving the use of various geotechnical modeling software programs. MM&A provides accurate, detailed, cost effective geotechnical characterization and assessment by coupling a “hands-on” traditional approach with modern geotechnical assessment software modeling techniques.
Open Pit Slope Stability
Marshall Miller & Associates conducts slope stability assessments for open pit mines in various types of deposits. Locations for recent open pit slope stability geotechnical assessments completed by MM&A staff include a gold mine in Southern California, a copper mine in Utah, numerous granitic aggregate mines in North Carolina, and a dolomite quarry in Alabama. MM&A works with the client to optimize the geotechnical data collection process, which is often a very costly component of slope stability assessments, by incorporating traditional field mapping and core techniques with down-hole geophysics, drone work, and wall scanning technology. MM&A completes both deterministic and probabilistic assessments for discontinuity-dependent kinematic failures (plane, wedge, toppling), as well as assessments of overall rock mass stability involving Rock Mass Rating (RMR) and Geological Strength Index (GSI) characterization. Our staff of geologists and engineers work with clients to fully explain the results of the assessment, and to understand the potential mitigation actions.
Underground Mine Stability
Marshall Miller & Associates completes various types of underground mine stability work, ranging from geological hazard mapping for mine roof and floor stability, to pillar stability assessment and design. Our geotechnical staff also complete more specialized mining geotechnical projects involving slope and shaft design, mine seal design, and bulkhead design. MM&A staff utilize a variety of software modeling packages as part of the overall assessment process, including the NIOSH Ground Control Toolbar, LaModel, FLAC3D, and programs by Rocscience. Our assessments couple proven data collection techniques such as core logging and underground mine mapping, with down-hole geophysical logging technology and computer modeling.
Mine Subsidence and Long-Term Landscape Stability Modeling
MM&A staff complete assessments of expected ground subsidence resulting from existing or proposed underground coal mines. Projects involve prediction of ground deformation associated with longwall coal mines as well as room-and-pillar retreat mining, and prediction of the long-term potential for deformation of the ground surface in areas overlying historic mining. Mine subsidence prediction is essential for mine planning to avoid unnecessary damage to surface structures, and to assess the degree of expected damage and identify potential mitigative actions. Assessment of long-term landscape stability is important for identifying the potential damage to surface structures resulting from subsidence caused by long-term destabilization of old underground mines. MM&A staff also complete projects assessing far-field horizontal displacements associated with longwall mine subsidence.
Down-Hole Geophysical Logging
Marshall Miller & Associates includes an in-house down-hole geophysical logging department, specializing in collection of geologic, hydrogeologic, and geotechnical data from drill holes of all types. With respect to geotechnical assessment for both surface and underground mining, MM&A’s down-hole geophysical logging capabilities include collection of discontinuity orientations, via Acoustic Televiewer (ATV), without the use of oriented core drilling. Our down-hole geophysical logging capabilities also include collection of full-wave sonic data for estimation of rock strength, collection of natural gamma and density data for geologic characterization, and collection of fluid temperature, conductivity, and porosity data for hydrogeologic characterization. MM&A regularly integrates down-hole geophysical data into projects to optimize data collection efforts and to enhance the quality and abundance of available data.