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SLOPE STABILITY OCTOBER 2017 • E&MJ; 51 www.e-mj.com Brown said. "TSLOPE can fit a surface to the points, and that is used to define the ground surface in our 3-D model." Other data can be imported to add definition. "If the slope is controlled by local stratig- raphy, we can import surfaces to form lay- ers in our 3-D model," he said. "Ground- water surfaces can also be imported." Thus, "there are no limits" to the complexity of the resulting slope stabil- ity analysis models, Brown said. "Once all the geometric and strength data are loaded, the slope is discretized into an ar- ray of vertical columns that are bounded by the open-pit ground surface and the failure surface," he said. "Loads can be applied to the model if appropriate." The user hits "Solve" to automatical- ly find the direction of least resistance to sliding and to calculate a Factor of Safe- ty (FoS). "TSLOPE provides output that helps understand which parts of the slope are resisting sliding, and which parts are driving the failure," Brown said. "This then helps the engineer design measures that will improve stability, such as slope drainage, and reinforcement." TSLOPE findings can be cross-referenced with monitoring data to validate the model. In analyzing possible critical failure surfaces, arbitrary sections are cut from the 3-D model to provide 2-D surfaces. "The program then discretizes the model into regular 2-D slices, the equivalent of our 3-D columns," Brown said. "TSLOPE has a search routine to find the circular failure surface (in 2-D) that has the low- est FoS, called the critical failure sur- face." Once it is determined, the slope will fail, "the TSLOPE model can be further calibrated by adjusting the shear strengths in the model to give a calcu- lated FoS of one," he said. TSLOPE can then automatically solve for the slope's pseudo static acceleration, the critical seismic coefficient. After a failure, TSLOPE can be used to show the range of strengths required for equilibrium. "If the failure can be recon- structed in a TSLOPE model, we can then use the back-analysis option to provide a cross plot of cohesion versus phi (for Mohr Coulomb strength) for a range of factors of safety, or for two of the four Generalized Hoek-Brown parameters if using that non- linear failure criterion," Brown said. "This is an important feature." By using TSLOPE, a miner can do complex modelling and analysis in-house, reducing the need for expensive con- sulting services, Brown said. "Man- agement are able to empower their staff to carry out complex slope sta- bility calculations with a simple work flow that fits into the technical ser- vices environment of a mine site." TSLOPE is li- censed on a time basis, "with modest pricing," Brown said. "In response to cus- tomer demand, we have made a day license available, as well-orga- nized users are able to get their slope stability analyses completed in a short time." The program is downloaded from and the licensing is arranged via the company's website, www.tagasoft.com. A two-week trial is free. Affordable, Fast Solutions Released in late June, Rocscience's Slide 3 , 3-D slope analysis and modeling software, is pitched as more than an update to best-selling predecessor software. Com- pany literature reports it leverages paral- lel processing, and is more than 10 times faster than the competition. Not only fast, it cranks out robust models and features sophisticated analytics. The software can automatically calculate the safety factor of bullnoses, large open-pit excavations and the effects of buttressing. "To build Slide 3 , we leveraged the platform of RS 3 , our 3-D finite element analysis software, which allowed us to create the complex 3-D ge- ometries required for slope stability mod- els," said Dr. Thamer Yacoub, president, Rocscience. Other features include ease- of-use, calculation "of any failure direction without user definition," and "superior methods for locating critical slip surfaces of any shape," the company reported. The software, described by Yacoub as "a stand-alone companion tool that en- gineers can use to enhance their models and analyses," was developed in-house and released for beta-testing in May. "Our customers provided essential feedback that has improved the usability and func- tion of the software to reduce the time burden of creating complicated models," Yacoub said. And while processing speed is a defining quality, the software sells be- cause it remedies some of "the complexity of open-pit geometry," Yacoub said. "The combined use of 2-D and 3-D models allows users to gain a better understand- ing of rock mass behavior, particularly in anisotropic rock masses, provides a more robust solution for slope design optimiza- tion, and aids in unlocking and maximiz- ing value from a mineral deposit." he said. One such solution is the Weak Layer function, which generates models of po- tential failures caused by the intersection of joint planes and other discontinuities. Rocscience literature states the software "will generate a multi-planar wedge fail- ure surface and calculate the safety fac- tor." The tool "covers cases when you have faults, factures, or joints in your rock mass and you want to study more compli- cated wedge failure for slopes," Yacoub said. "This ability to examine different failure mechanisms more accurately leads to a more precise FoS." Another solution is dubbed Surface Altering Optimization, which enables au- tomated modeling of potential critical slip surfaces with "minimal user input," the company reported. First, "initial trial sur- faces can be generated using Spheres or Ellipsoids," Rocscience literature stated. Yacoub said "the surface is initially ap- proximated into non-uniform rational ba- TSLOPE can reveals which parts of a slope are resisting sliding, and which parts are driving the failure. Above, a TSLOPE screenshot. (Photo: TAGAsoft)