Dear clients,
We are delighted to announce that we will be a Gold Sponsor at the Slope Stability Conference. This event will take place in April 11th to 13th in Sevilla. During the 3-day conference, our team will be available to demonstrate, discuss and listen to your feedback at Booth #10, located next to the main entrance of the exhibition hall. We are looking forward to connecting with our customers and networking with prospective clients.
Consulting
Itasca Consultores SL was asked to analyze the stability of an underground water storage facility in shale ground at 300 m depth. The facility is formed by a set of parallel galleries (200 m long, 5.0 m wide and 6.5 m high) spaced 20 m between walls. The stability of the pillar between galleries was analyzed first. A FLAC3D model that simulates the strength of a square pillar was calibrated against the Abel-Wilson-Aswin formula for square pillars in weak rock. Once a FLAC3D model was calibrated, the strength of the longitudinal pillar between galleries was analyzed with a plane-strain model; the model is presented in Figure 1, and the stress-strain curved of the longitudinal pillar is presented in Figure 2. | |
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Figure 2. Stress-strain curve for longitudinal pillar |
The support designed for the galleries and the junctions between access-galleries and storage-galleries were analyzed with 3D models that simulate the sequential process of excavation, support, and curing of the shotcrete. Curing is simulated with a progressive increase of the stiffness with the face distance (Figure 3), and the stresses in the shotcrete were finally checked with moment-thrust diagrams (Figure 4). | |
Figure 3. Liner elements with increasing stiffness |
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Itasca Consultants AB (Sweden) has assisted the Boliden Kevitsa open pit mine with stability analysis as input to their strategic plan. A new pit optimization project is undertaken at the Boliden Kevitsa Mine in northern Finland, to investigate an increase in production. In conjunction with this, the geotechnical slope design parameters for the final pit depth, including a possibly deeper pit, need to be analyzed. Our work included assessment of slope stability for future open pit mining at Kevitsa for all scales — from benches to overall slopes, including: (i) total slope angles for final pit depths, (ii) interramp slope angles, (iii) maximum interramp height, (iv) bench slope geometries, (v) recommendations on slope depressurization, and (vi) recommendations for slope monitoring and further data collection. The work demonstrated the current state-of-the-art for both large-scale stability analysis (2D and 3D modeling) and kinematic analysis for benches and interramp slopes, incorporating acquired experiences and knowledge from large open pits worldwide. For the bench and interramp slopes, a combined analysis considering spill length, catchment criteria, and kinematic stability was conducted, and validated against the as-built geometry of the current pit. This work was also presented at the SME Annual Conference in Minneapolis, February 25–28, 2018. | |
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Distribution of von-Mises-Stress after backfill of the first room |
Example of Factor-of-Safety calculations |
