Success Stories

August 21, 2013

Overview

Anddes Asociados S.A.C. recently dealt with a difficult project in northern Perú involving a three dimensional (3D) slope stability analysis of a waste dump. The stability analysis for this facility involved a complex mine waste rock layout and many different soil layers at the foundation, most of them affecting the waste dump stability. This problem was successfully solved by using SVSlope®3D.

Due to the mining expansion and the increment of production required by a mining company in northern Perú, the waste dump needed a redesign to get a capacity of 113 million tones (66 million of cubic meters), with an area of 118 Ha. The angle of repose of the waste rock will form a slope of 1,5H:1V, and with an overall slope of 2,5H:1V. A referential area of this facility is shown in Figure 1.

Figure 1: Future area of the waste dump designed by Anddes.

Anddes Asociados S.A.C., an innovative and rapidly growing Peruvian consulting company, was hired by the mining company to carry out the waste dump design, whose configuration is shown is Figure 2. The work included an extensive geotechnical investigation program for waste rock and soil foundation characterization. This investigation involved a large quantity of field data which included: 123 test pits, 31 dynamic penetration tests (DPL), 91 standard penetration tests (SPT), 30 large penetration tests (LPT) and 21 geotechnical boreholes among many laboratory tests needed to model accurately the soil and rock materials present.

As a result of the geotechnical investigation, it was determined that the waste dump foundation was conformed by very heterogeneous soil layers, most of them compromising the stability of this facility, so that there could be sections with high factor of safety and others nearby with poor stability conditions, as shown is Figure 3.

Figure 2: Layout of the waste dump.

Figure 3: Different geotechnical cross-sections of the waste dump, showing the heterogeneous soils in the foundation and complex waste rock stored.


Analysis

As a first approach, to analyze the overall slope stability of the dump, the two most critical sections were analyzed, as shown in Figure 2. Both sections represent quite different foundation conditions. For instance, one section failure was governed by soft alluvial clayey soils and the other by loose residual soils. Both sections had a 2D factor of safety lower than the minimum required by the design criteria using the Spencer limit equilibrium method.

A reliable 3D slope stability program was required that could deal with issues such as: variability of strong and weak layers in the waste dump toe foundation, actual dike geometry, and actual 3D geometry. SVSlope®3D was chosen as the modeling tool as it met these criteria.

Since the geotechnical information provided along the waste dump foundation was abundant, two models were created for the analysis. 15 geotechnical sections were developed for Model 1 and 19 for Model 2 by Anddes´ geotechnical and geological engineers. Each section was separated by 50 m. It is important to mention that both models were created around the two most critical sections previously analyzed. Figure 4 presents both areas modeled in SVSlope®3D.

Figure 4: 3D view of Model 1 and 2 analyzed in SVSlope®3D.

All the point data contained in each section was uploaded to the program using Excel files. The program managed to interpolate over 30 sections in both models. During this process 11 surfaces were created, showing geotechnical complexity related to this case. Moreover, lenses of loose soil layers represented in the geotechnical sections were easily processed and they could be smoothly found in the models. SVSlope®3D adequately represented the 3D waste dump stacking as if it were modeled in any CAD software.

Figure 5: Most critical slip surface analyzed in Model 1.

The Spencer rigorous limit equilibrium method was used as well to determine the exact relation of 2D and 3D factor of safety. The search method used to determine the failure surface was the grid and tangent method. Many analysis were performed, each one increasing the grid density in the most critical zones and using different eccentricity ratios for the ellipsoid geometry. Figure 5 shows the most critical surface found in Model 1.


Conclusion

The results were successful in the sense that the 3D factor of safety overcame the minimum required by the project. Moreover, the 3D factor of safety was around 10% larger than the 2D one. This can be explained by considering that the 3D analysis encounters strong layers in addition to weak layers and takes into account the 3D topography of the site, both of which contribute to the overall stability of the facility. The soil layers cut by the 3D slip surface can be seen in Figure 6.

Figure 6: 2D view in SVSlope®3D of Model 1. It should be noted that strong and weak soil layers are involved in the 3D analysis.


Almost two months ago, we overcame some issues concerning cross-sectional data entry with the help of you and your development team, and this is the final result of our work. We hope we can keep working together."

Andrés Reyes Parra, Geotechnical Engineer, Anddes Asociados S.A.C., Lima, Perú

If you are interested in this type of analysis, the SVSLOPE® 3D software package is available. Please visit our ordering page for pricing and purchase information, or contact us directly.


Testimonials

  • "I would like to thank you for all the support and the interest that I got from your team regarding this matter. I was able to successfully finish my project with the help of your technical support and managed to graduate achieving a high grade on the project I did. The software is extremely helpful and wasn't complicated and I look forward to future for more work and experience with your software. Thank you for your help and support."
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    In my opinion, this software is easy to learn and fun to use. The built-in tutorials are sufficient to get one started. With these tutorials, my students were generally able to complete their analyses with minimal involvement on my side.

    Based on my own experience, it takes around a month of full-time use to become reasonably competent with the software (provided that one understands the theoretical underpinnings of this type of analysis) - a short learning curve, compared to other products of similar complexity. The interface is intuitive enough for me to figure out things on my own, and I rarely had the need to ask for help.

    I don't generally like praising anything excessively, and I don't post particularly glowing reviews for anything. Having said that, I must mention the SoilVision support. At some point during my research, I was conducting a number of replication studies for my thesis. In that period, I must have emailed SoilVision's support anywhere from 2 to 5 times a day, with fairly complex (and sometimes very dumb) questions. I always got a response by the end of the day, and a resolution within a couple days at most. In a number of urgent cases (such as during a tutorial session with a classroom of students) I called them directly on the phone and, with senior product engineers involved, had the issue addressed in minutes."
  • "We have allowed our students the choice of using multiple Geotechnical software suites in our Dam Design and other Geotechnical courses. Our students consistently gravitate towards SoilVision software as being the most modern and user-friendly."

  • "I've been a geotechnical engineer for more than 25 years and SoilVision has the best tech support I have ever worked with. I truly appreciate their patience and help over the past year."

  • "Peter Brett Associates have been looking to update our existing slope stability software over the last year. After extensive research and trials, SVSLOPE® developed by SoilVision Systems Ltd. was found to meet all our existing and future design requirements. Its ease of use for modeling simple as well as complex geological and geometrical problems was a critical factor in our assessment as well as the incorporation of design to the Eurocodes. Their customer support has been faultless and their willingness to develop the software to meet our own specific design requirements is a most gratifying added bonus."

    "We love the fact that SVSLOPE® is part of an integrated suite of software and that, if required, 3D analysis can be undertaken. We would recommend this product to other geotechnical consulting firms."

  • "We have been using SVSLOPE® and SVFLUX™ for the past year and have found them to be efficient and productive engineering tools which have allowed us to offer our services in an efficient manner. The capability of automated increased discretization of the mesh is an absolute benefit to our modeling, reducing time and effort. We have found the software quick and easy for our engineers to train and utilize. I would recommend this product to other geotechnical consulting firms."

  • "The software is well documented and comes with number of useful example models. We were able to quickly begin creating models after a short review of the user interface and going through the available on-line webinars. The software offers solid benefits of less conservatism and the ability to model real geometry."

  • "This new software for stability analysis includes a number of state-of-the-art options for probabilistic slope stability analysis. This feature, combined with comprehensive deterministic analyses, will provide new opportunities to build confidence in the results of a site-specific analysis.”

  • "I'm excited to see the release of this new and innovative product. I look forward to and encourage the application of this software on additional geotechnical projects.”

  • "In consulting engineering practice, I am increasingly made aware of the important and beneficial role that modeling the unsaturated soil zone can play in providing the client with the best possible engineered solution. The SoilVision software has made it possible to readily estimate and incorporate unsaturated soil properties into the modeling of saturated / unsaturated soil systems.”

  • "The use of SVSLOPE® software as part of a research project on clay slopes under seismic conditions with the Université de Sherbrooke has been incredibly easy and effective. The continuation of this research with SoilVision is promising, with technical support, which was present at the right time, as well as a passionate geotechnical team supporting the project.”

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