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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Innovative methodology for location-based scheduling and visualisation of earthworks in road construction projects

Shah, Raj K. January 2011 (has links)
This thesis focuses on the development of an innovative location-based scheduling methodology and a computer-based model for improving earthwork operations in road construction projects. Analysis of existing planning and scheduling practices in road construction projects conducted in the course of this research concluded that planning, scheduling and resource allocation are largely dependent on subjective decisions. Also, shortcomings exist due to the distinct characteristics of earthworks, e.g. one-off projects with uncertain site conditions and soil characteristics, causing delays and cost overruns of projects. The literature review found that existing linear scheduling methods provide inaccurate location-based information about earthworks and fail to integrate different productivity rates. A survey was used to capture and analyse industrial practices and issues related to delays and cost overruns. This analysis revealed that the accurate location-based information is vital for efficient resource planning and progress monitoring. Following these findings, a theoretical framework and specification were developed to automate location-based scheduling and visualisation of information. A prototype model was developed by integrating road design data, sectional quantities, productivity rates, unit cost, site access points, and arithmetic algorithms. The algorithms underpinning the model enable the generation of time-location plans automatically as a key output of the model. Weekly progress profiles, space congestion plans, and cost S-curves are the other outputs. A cut-fill algorithm was developed to identify optimum quantities of earthwork and its associated costs. Experiments were conducted with design data provided by a road construction company to demonstrate the model‟s functionality. Sensitivity analysis was used to identify the critical factors relating to earthwork scheduling. It was found that the model is capable of generating time-location plans, considering the critical factors and location aspects. Finally, the model was evaluated using a case study and validated by road construction professionals using an indirect comparison method. It was concluded that the model is a valuable tool for producing location-based scheduling, optimising resource planning and assisting in the communication of scheduling information from the location viewpoints in the earthwork projects.
2

A Middle to Late Holocene Record of Arroyo Cut-Fill Events in Kitchen Corral Wash, Southern Utah

Huff, William M. 01 May 2013 (has links)
This study examines middle to late Holocene episodes of arroyo incision and aggradation in the Kitchen Corral Wash (KCW), a tributary of the Paria River in southern Utah. Arroyos are entrenched channels in valley-fill alluvium, and are capable of capturing decadal- to centennial-scale fluctuations in watershed hydrology as evidenced by the Holocene cut-fill stratigraphy recorded within near-vertical arroyo-channel walls. KCW has experienced both historic (ca. 1880-1920 AD) and prehistoric (Holocene) episodes of arroyo cutting and filling. The near-synchronous timing of arroyo cut-fill events between the Paria River and regional drainages over the last - 1 have led some researchers to argue that arroyo development is climatically driven. However, the influence of allogenic (climate-related) or autogenic (geomorphic threshold) forcings on arroyo dynamics are less clear. Uncertainty in influence of the controlling mechanisms of arroyo cutting and filling is partly due to the limited or poorly dated alluvial chronologies. This study tests the applicability of AMS radiocarbon and optically stimulated luminescence (OSL) dating to reconstruct alluvial chronologies in dryland fluvial systems, such as the KCW arroyo. Results from 12 arroyo-wall study sites in KCW indicate that 24 of the 39 analyzed AMS radiocarbon sample s and preliminary results from 12 of the 14 OSL sample s returned strati graphically consistent ages. Applying a combination of these two dating techniques allowed for increased sampling opportunities and cross-checking of ages to determine aberrant age results. By using detailed stratigraphic panels, sedimentologic descriptions, and the age control from AMS radiocarbon and OSL dating, this study produces a new chronostratigraphy that suggests at least five arroyo cut-fill cycles during the middle to late Holocene with periods of aggradation at: - 4.3 5 - 3 .4 ka (Qfl ), - 3 .2 - 2.25 ka (Qf2), - 2. 15 - 1 .45 ka (Qf3), - 1.3 - 0.8 ka (Qf4), - 0. 7- 0.12 ka (Qf5), and an older period of aggradation from - 7 .3 - 4.85 ka identified in an earlier stud y. This newly developed KCW cut-fill chronostratigraphy is compared to regional alluvial and paleoclimate records to test hypotheses regarding allogenic or autogenic forcings. Regional alluvial chronologies do not show coherent patterns of arroyo cut -fill dynamics, but instead appear to be affected by both allogenic and autogenic influences.
3

Land Leveling Using Optimal Earthmoving Vehicle Routing

McInvale, Howard D. 30 April 2002 (has links)
This thesis presents new solution approaches for land leveling, using optimal earthmoving vehicle routing. It addresses the Shortest Route Cut and Fill Problem (SRCFP) developed by Henderson, Vaughan, Wakefield and Jacobson [2000]. The SRCFP is a discrete optimization search problem, proven to be NP-hard. The SRCFP describes the process of reshaping terrain through a series of cuts and fills. This process is commonly done when leveling land for building homes, parking lots, etc. The model used to represent this natural system is a variation of the Traveling Salesman Problem. The model is designed to limit the time needed to operate expensive, earthmoving vehicles. The model finds a vehicle route that minimizes the total time required to travel between cut and fill locations while leveling the site. An optimal route is a route requiring the least amount of travel time for an individual earthmoving vehicle. This research addresses the SRCFP by evaluating minimum function values across an unknown response surface. The result is a cost estimating strategy that provides construction planners a strategy for contouring terrain as cheaply as possible. Other applications of this research include rapid runway repair, and robotic vehicle routing. / Master of Science

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