Economic Excavator Configuration for Earthwork Scheduling

Journal of Construction Engineering, Management & Innovation, 2018

An excavator is a construction machine that is used at constructions which involve earthworks. Pallet or wheeled ones are preferred according to the site conditions. When choosing an excavator, the unit cost of the excavation and the duration of the excavation task play an important role. There are various factors that affect efficiency of the excavator and speed of the excavation. Factors such as bucket volume of the excavator, bucket fill rate, cycle time, swing angle, type of excavated ground, as well as environment and weather conditions influence the performance of the excavators. In this study, software which estimates duration of the excavation and number of required trucks by considering different ground and environmental conditions is developed. Moreover, the software takes hauling distances and job conditions into account. The developed software calculates statistically the effect of the uncertainties in the input parameters from the randomly generated numbers by the Monte Carlo Simulation method. The software is developed by C++ programming language. Developed software can be helpful for the state institutions and private firms to determine the risks of the time and cost estimates.

2012

Pile foundations, loading area layout, excavation depth, haul distance, operator skills, and other factors, complicate the estimation of the production rates and unit cost of excavation operation. Simulation can be used as a tool to assist construction engineers in analyzing and designing construction operations. The objective of this paper is to develop a simulation model for the excavation operation in building construction to provide planner and estimators with a powerful tool for predicting the production rates and unit cost. Moreover, this model facilitates the investigation of resources’ combination effect on this operation. For this purpose, the model was developed using realistic activities durations. Therefore, full-time observations were conducted to collect these data from several building projects constructed in the city of Alexandria (Egypt). Based on the results, the impact of resources’ combination and variation of these resources on the production rates and unit cost...

By virtue of its complex nature, the construction industry comprises a wide spectrum of interrelated variables and factors. This multifaceted character of the construction industry puts the use of engineering modeling tools and techniques on top of project management necessities. This research introduces a macro-level earthmoving management system using Genetic Algorithms (GAs) to reach the optimum allocation of earthmoving equipment. The Earthmoving Equipment Management System (EEMS) functions through four integrated modules: (1) A Central Database containing information about projects and available equipment; (2) An Equipment per Segment Selection module that calculates the cut and fill quantities, plots the Mass Haul Diagrams, and selects the equipment types to be used for each segment; (3) An Equipment Pool module which determines the production and cost for each available equipment, based upon the project site conditions; and (4) An Optimization Engine equipped with a GA optimi...

Journal of Construction Engineering, Management & Innovation, 2021

In this study, a decision support system is developed to aid selection of earthwork equipment. Physical and economical attributes of five off the shelf dozers, three excavators, and seven hydraulic hammers are entered to a spreadsheet application. Seven seismic velocity-mechanical property relationships of rock and stiff soil are derived from the literature and defined to the spreadsheet application. Mechanical properties of the soil samples obtained from the construction site are entered to the relevant data cells and seismic velocity to be measured at the field is estimated. Developed system estimates the ripper outputs of the dozers by using ripper production charts, cost and duration of the earthwork task is computed and likelihoods of the feasibility of the construction machines are estimated. Developed system takes the construction duration into account and solves time-cost trade-off problem for the selection of the best construction machine. Developed methodology is implemented on the excavation of the foundations of a mass public housing project with 72 houses. Utilization of ripper production charts without performing seismic velocity tests become possible by the proposed method. Furthermore, time cost trade-off problem is formed and solved without human interruption. The developed decision support system proposes the construction machine with least total direct and indirect costs. Contractors would be able to reduce their construction costs and gain competitive advantage on their rivals, if they implement the proposed system.

— Earthmoving and constructing equipments have evolved significantly during the past century. In every construction project some type of excavation must be performed. Excavators are primary earthmoving machines and equipment used to excavate earth and related materials. Contractors generally depend on their experience for selecting the right excavator for a job. Hence there is a need to build an understanding of how machine usage affects performance, extending across productivity. This study focuses on study of actual productivity against the theoretical productivity to demonstrate the loss of productivity. This real time monitoring of the heavy equipment can help practitioners improve machine intensive and cyclic earthmoving operations.

Industrial Engineering and Management Systems

In this paper, an interactive planning and scheduling framework are proposed for optimising operations from pits to crushers in ore mining industry. Series of theoretical and practical operations research techniques are investigated to improve the overall efficiency of mining systems due to the facts that mining managers need to tackle optimisation problems within different horizons and with different levels of detail. Under this framework, mine design planning, mine production sequencing and mine transportation scheduling models are integrated and interacted within a whole optimisation system. The proposed integrated framework could be used by mining industry for reducing equipment costs, improving the production efficiency and maximising the net present value.

It is common practice for underground mine plans to be created sequentially, where results from one planning process form the input data for another. While this is practical for manual methods, computerized optimization techniques should consider an integrated approach to creating the global mine plan. This is because optimizing an individual mine planning process, such as stope layouts, introduces a likelihood of increasing costs or decreasing revenues associated with other areas, such as production scheduling, as harmful decisions must be balanced. Considering the interaction and influence that individual underground mine planning processes have on each other during optimization will provide more profitable results than if these are ignored. Optimization techniques for stope layouts and production scheduling are reviewed. An integer programming model is proposed that allows for either integrated or isolated optimization. Both approaches are separately applied to a block model. The results demonstrate the model's ability to produce optimal long-term sublevel stoping mine plans and the benefits of using an integrated approach.

2018

Scheduling of underground mining activities is based on the correct allocation of resources to ensure the fulfilment of the required physical advance of the project. In the case of mining tunnel construction, the scheduling of activities is based on three aspects – availability of required services of each unit operation (power, ventilation, industrial water, compressed air and drainage), availability of resources required (equipment and mining crew), and availability of faces for physical allocation and resource utilisation. In block caving mining projects, the development involved, particularly in the production level, is associated with multiple faces, which makes the allocation of resources complex compared to operations with isolated faces where resources are captive. Given the multiple face scenario, a scheduling model was generated based on the integration of the availability of the three aspects previously mentioned – faces, resources and services. These parameters are integ...

2018

For the past few years, the mining industry has seen a lot of operational changes. Digitalization and automation of many processes have paved the way for an increase in its general productivity. In keeping with this trend, this article presents a novel approach for optimizing underground mine scheduling for the shortand medium-term. This problem is similar to the Resource-Constrained Project Scheduling Problem, with some particularities. The model uses Constraint Programming principles to maximize the Net Present Value of a mining project. It plans work shifts for up to a year in advance, considering specialized equipment, backfilling and operational constraints. Results from its applications to datasets based on a Canadian gold mine demonstrate its ability to find optimal solutions in a reasonable time. A comparison with an equivalent Mixed Integer Programing model proves that the Constraint Programming approach offers clear gains in terms of computability and readability of the co...