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Tunsakul J.,King Mongkuts University of Technology Thonburi | Jongpradist P.,King Mongkuts University of Technology Thonburi | Soparat P.,Bureau of Planning | Kongkitkul W.,King Mongkuts University of Technology Thonburi | Nanakorn P.,Thammasat University
Computers and Geotechnics | Year: 2014

Fractures developed around high pressurized gas or air storage tunnels can progressively extend to the ground surface, eventually leading to an uplift failure. A tool reasonably reproducing the failure patterns is necessary for stability assessment. In this study, a numerical method based on the element-free Galerkin (EFG) method with a cohesive crack model is developed to simulate fracture propagation patterns in the rock mass around a tunnel under high internal pressure. A series of physical model tests was also conducted to validate the reliability of the developed method. A qualitative agreement between physical model tests and numerical results can be obtained. The in situ stress ratio, k, has a strong influence on both the position of crack initiation and the propagation direction. The numerical analyses were extended to full-scale problems. Numerical tests were performed to investigate the prime influencing factors on the failure patterns of a high pressurized gas circular tunnel with varying parameters. The results suggest that initial in situ stress conditions with a high k (larger than 1) is favorable for construction of pressurized gas or air storage tunnels. © 2013 Elsevier Ltd. Source


Paraphantakul C.,Bureau of Planning | Miller-Hooks E.,University of Maryland University College | Opasanon S.,Thammasat University
Transportation Research Record | Year: 2012

The problem of truckload delivery with backhaul scheduling was formulated, and a methodology for ant colony optimization that was developed for a related problem, the problem of vehicle routing with backhaul and time windows, was adapted for the solution of the truckload delivery problem. The problem of truckload delivery with backhaul scheduling differs from the problem of vehicle routing with backhaul and time windows in that shipments are in units of truckloads, multiple time windows in multiple days are available for delivery to customers, limited space for servicing customers is available, and multiple visits to each customer may be required. The problem is motivated by a real-world application arising at a leading cement producer in Thailand. Experts at the cement production plant assign vehicles to cement customers and lignite mines on the basis of manual computations and experience. Mathematical and computational frameworks are provided for modeling and solving this real-world application. Source


Chen A.,Utah State University | Chootinan P.,Bureau of Planning | Ryu S.,Utah State University | Wong S.C.,University of Hong Kong
Journal of Transportation Engineering | Year: 2012

The goals of this paper are to (1) provide a review of the recently developed measures for assessing the quality of origindestination (O-D) trip tables estimated from traffic counts and (2) propose a new generalized demand scale (GDS) measure. This GDS quality measure generalizes the total demand scale (TDS) quality measure by allowing the assessment of the intrinsic underdeterminant problem of O-D estimation from traffic counts at various spatial levels. Numerical examples are provided to compare the proposed GDS measure with the TDS measure, the maximal possible relative error, and the expected relative error and to illustrate the features of the GDS measure. © 2012 American Society of Civil Engineers. Source


Chen A.,Utah State University | Chootinan P.,Bureau of Planning | Ryu S.,Utah State University | Lee M.,University of Alaska Fairbanks | Recker W.,University of California at Irvine
Journal of Advanced Transportation | Year: 2012

Estimation of intersection turning movements is one of the key inputs required for a variety of transportation analysis, including intersection geometric design, signal timing design, traffic impact assessment, and transportation planning. Conventional approaches that use manual techniques for estimation of turning movements are insensitive to congestion. The drawbacks of the manual techniques can be amended by integrating a network traffic model with a computation procedure capable of estimating turning movements from a set of link traffic counts and intersection turning movement counts. This study proposes using the path flow estimator, originally used to estimate path flows (hence origin-destination flows), to derive not only complete link flows, but also turning movements for the whole road network given some counts at selected roads and intersections. Two case studies using actual traffic counts are used to demonstrate the proposed intersection turning movement estimation procedure. © 2010 John Wiley & Sons, Ltd. Source


Chen A.,Utah State University | Pravinvongvuth S.,DKS Associates | Chootinan P.,Bureau of Planning
Transportmetrica | Year: 2010

Recently, a multi-objective model for locating the automatic vehicle identification (AVI) readers in a transportation network was proposed by the authors along with its solution procedure. The model locates the AVI readers by simultaneously considering three objectives: the equipment and installation cost (e.g. number of AVI readers), the coverage of the AVI system (e.g. number of origin-destination (O-D) pairs), and the amount/quality of travel information obtained (e.g. number of AVI readings). However, only a single travel demand pattern for a certain time period, such as the evening peak hour, was considered in determining the AVI reader locations. Therefore, the recommended AVI system may not be able to guarantee the amount of travel information gathered during other time periods. This study extends our previously proposed model by developing three scenario based models to accommodate different travel demand patterns observed during the whole day. A case study is provided to illustrate the applicability of the new models and the robustness of the AVI system designed by considering different travel demand patterns. © 2010 Hong Kong Society for Transportation Studies Limited. Source

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