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<< Click to Display Table of Contents >> Truck & Shovel Simulation |
  
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<< Click to Display Table of Contents >> Truck & Shovel Simulation |
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Prerequisites
The material in this section requires an understanding of the topics covered in Automated Excavation Sequencing , Automated Dump Sequencing and Setting up Haul Roads and Accesses.
Previous topics described the procedures for setting up a Supersequence to implement a proposed mining schedule, and assigning Dumps to the Subsequences in this Supersequence such that all excavated material reports to the proposed Dumps. Running a Supersequence with assigned Dumps simulates the topographic affects of a proposed mining schedule.
The Truck and Shovel simulation module adds fleet productivity to the topographic simulation.
The foundation of truck and shovel simulation is the topographic simulation involving Staged Excavations, Staged Dumps, Supersequences and Dump assignment.
Review of topographic simulation
The basic principles of topographic simulation are:
•A Staged Excavation is used to set up a strip for modelling. It allows the user to define strip limits,Passes, Lifts and Block lines.
•The Staged Excavation functionality takes the user defined set up and produces a Raw Sequence. A Raw Sequence consists of an ordered set of Steps. The user assembles the Steps into Subsequences.
•A Step is the smallest increment of the simulated excavation. Each step Spans to block lines (block n and block n +1) in the horizontal plane, and vertically extends over a pass, or if lifts are defined it spans the lift vertically.
•A Subsequence is a (usually) contiguous set of Steps which share common characteristics such as dumps to which excavated material reports,equipment fleet and haul routes.
•A Supersequence is used to implement the desired schedule. Supersequence is an ordered structure in which the elements are Subsequences. Each Subsequence is processed in the order in which it appears in the Supersequence.
•The Staged Dump is used to model truck and shovel dumps. It allows a dump conforming to a design to be built progressively in Lifts and Passes.
•A hierarchy of Staged Dumps can be assigned to a Subsequence. Material excavated from the Subsequence reports to the first Dump in the hierarchy, when this is full it reports to the next and so on as required.
•When all waste Subsequences in a Supersequence have Dumps assigned, and the Supersequence is run the full topographic affects of excavation and dumping are simulated.
•The smallest increment of the topographic simulation is a Step (block) of a Subsequence. Subsequences are excavated one Step at a time, once a Step is excavated its material is dumped and the next Step is excavated and dumped and this process continues until all Steps in the Subsequence have been processed.
Method productivity calculation.
The Truck and Shovel simulation determines the haulage requirements for each Step of each Subsequence. The procedure used to determine productivity is as follows:
•The topographic simulation for a Step is conducted, material is excavated and dumped at the assigned dump.
•With the source and destination of waste known, a haul route is determined. At its most detailed the haul route includes excavation access, main haul and dump access.
•With the haul route determined truck simulation along the haul route can proceed. Fleet productivity calculation allows for excavator time (including bucket load and variations in load and fill time), truck dynamics (travel time, queue time etc.) and unscheduled and scheduled downtime.
•The total time required to excavate the Step is determined using the above methods, then the following Step is excavated and processed in the same manner. This procedure continues for the Subsequence and for all Subsequences in the Supersequence.
Using the above method 3d-DigPlus is able to produce accurate haul routes four each increment of the simulation. This haul route estimation is highly dynamic of haul routes varying as necessary from from Step to Step. When a Dump in a hierarchy is full and dumping progresses to the next Dump an entirely new haul route is established. As excavation and dumping progresses within a particular dump the the haul route from Step to Step is constantly adjusted.
The following video clip illustrates these principles:
The first requirement of productivity simulation is to have the proposed schedule modelled via a Supersequence with assigned Dumps, as described above. Once these elements are in place the following additional elements are required to simulate truck and shovel productivity:
•A system of roads and accesses capable of connecting all excavation sites to all dump sites.
•Appropriate assignment of the road and access systems to all waste Subsequences.
•A model of all excavators proposed for use in the schedule.
•A model of all truck types proposed for use in the schedule.
•Appropriate assignment of equipment to Subsequences.
•Setting up unscheduled and scheduled downtime.
The following topics explain these various elements.