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Fowze J.S.M.,Asian Institute of Technology | Bergado D.T.,Asian Institute of Technology | Soralump S.,Kasetsart University | Voottipreux P.,King Mongkut's University of Technology Bangkok | Dechasakulsom M.,Bureau of Road Research and Development
Geotextiles and Geomembranes | Year: 2012

Recently, the frequency of rain-triggered landslides in Thailand has been on the increase and has gained momentum, coincident with the effects of climate change. In this regards, the impact of landslide on roads and highways in the hilly and mountainous terrains has also increased. Non-structural landslide mitigation measures, including early warning and hazard mapping, as well as structural mitigation measures with the application of geosynthetics, have been exploited in localities where rain-triggered landslides are a potential threat to human life and property. For early warning, the use of critical Antecedent Precipitation Index (API) is proposed to be most appropriate. Furthermore, deterministic hazard mapping technique incorporating the modern day geospatial technologies can also provide a useful platform to analyze a number of scenarios including rainfall and land cover/land use variations. Finally, a parametric study on a designed and constructed reinforced soil slope with polyester polymer geogrids revealed that the stiffness of backfill is very sensitive to moisture contents or wetting due to rainfall which can influence the performance of reinforced slope structure. © 2011 Elsevier Ltd.

Jotisankasa A.,Kasetsart University | Mahannopkul K.,Kasetsart University | Sawangsuriya A.,Bureau of Road Research and Development
Geotechnical Engineering | Year: 2015

Spatial and temporal variations of pore water pressure within slopes in response to rainfall that lead to slope failure, are one of the major uncertainties in evaluating slope stability. This paper reports on the study of slope stability with respect to pore water pressure variation with rainfall during actual failure in September 2011. The studied slope, situated near the peak of Doi-Inthanon national park, Northern Thailand, consisted of granitic residual soil fill that suffered from soil erosion and shallow failure. The KU-tensiometers were installed to monitor both pore water pressure and suction in the slope. Various laboratory and field tests were conducted, namely, direct shear tests on both fully saturated and unsaturated soils, soil water characteristic curve, and field infiltration tests. Two-dimensional (2-D) Back analysis of slope stability, for failure event in 2011 suggested that the critical pore water pressure distribution can be assigned to the ru value of about 0.43 or u=0.43γH. Based on three dimensional (3-D) stability analysis, the pore water pressure can be 30% higher when compared with the 2-D analysis. 2-D Finite Element seepage analysis appeared to capture general trend of pore-water pressure change reasonably well. However, it seemed to underpredict the pore-water pressure at failure especially for depth greater than 2 meters.

Jotisankasa A.,Kasetsart University | Mahannopkul K.,Kasetsart University | Sawangsuriya A.,Bureau of Road Research and Development
Unsaturated Soils: Research and Applications - Proceedings of the 6th International Conference on Unsaturated Soils, UNSAT 2014 | Year: 2014

This paper reports on the study of slope stability with respect to pore water pressure and suction variation with rainfall for highway No. 1009, Km 42, in Doi-intanon, Chaingmai, Northern Thailand. The slope consists of granitic residual soil fill that suffered from soil erosion and shallow failure. The KU-tensiometers were installed at depth of 0.5, 1, 2 and 3 meters to monitor both positive and negative pore water pressure along the slope and its variation with rainfall was discussed. Shear behavior and soil water characteristic curve of recompacted soils collected from the site were also studied in the direct shear box and with tensiometers. Stability analysis was also performed for a failed slope based on observed failure surface and shear strength using the effective stress analysis in order to determine the value of pore water pressure at failure. In this regards, the pore water coefficient, r+ADw-inf+AD4-u+ADw-/ inf+AD4-, was varied in the analysis until it was found that for Factor of Safety to be 1, the r+ADw-inf+AD4-u+ADw-/inf+AD4- value was about 0.43 which would have responded to a total daily rainfall of about 100 mm and 3-day antecedent rain of about 180 mm. This value of pore water pressure agrees reasonably well with the measurement of pore water pressure shortly after the failure indicating the plausibility of study results. © 2014 Taylor & Francis Group.

Sunitsakul J.,Bureau of Road Research and Development | Sawatparnich A.,Bureau of Bridge Construction | Sawangsuriya A.,Bureau of Road Research and Development
Geotechnical and Geological Engineering | Year: 2012

Unconfined compressive strength (UCS) of cement stabilized bases was collected from a number of highway construction projects in Thailand. Results from the statistical analysis indicated that the most important factors affecting the UCS were the CBR and the water to cement ratio. The UCS was however independent on the dry density. A statistical model was developed in the study to predict the UCS of cement stabilized bases. A model was developed based on the following criteria: (1) the dry density of the sample shall be greater than 95 percent of the maximum dry density based on the modified Proctor compaction, (2) samples shall be soaked for at least 2 h prior to testing, and (3) the CBR shall be measured at 0.1 inch (2.5 mm) penetration. © 2011 Springer Science+Business Media B.V.

Sawangsuriya A.,Bureau of Road Research and Development | Jotisankasa A.,Kasetsart University | Sukolrat J.,Bureau of Road Research and Development | Dechasakulsom M.,Bureau of Material Analysis and Inspection | And 3 more authors.
Geotechnical Special Publication | Year: 2013

This paper compared the erosion susceptibility and stability of repaired highway embankment slopes, which were composed of five different erosion control and slope protection methods. Each method comprised the combination of various erosion control and stabilization methods, i.e., vetiver grass, arachis pinto, soil blanket, soil log, clay sodding, geocell, and erosion control mat. A number of tensiometers were installed at various depths ranging from 0.5-3.0 m in order to monitor both positive and negative pore water pressure and seepage flow within the slope for each section. The amount of rainfall was also monitored using a tipping bucket-type rain gauge. The erosion control performance of five sections based on field observation suggested that a section consisting of soil blanket, soil log, and clay sodding appeared to be the most effective method when the amount of rainfall is less than 1,400 mm/year. However, as the accumulated rainfall of over 3,400 mm/year, all sections were suffered from severe shallow slope failure and surface erosion. Such failure agreed well with the pore water pressure data. The value of pore water pressure coefficient (ru) observed towards the end of wet season ranged from 0.40-0.50. The back analysis indicated that the shear strength parameters (c' and φ') were respectively 10 kPa and 40 degrees when ru is 0.55. © 2013 American Society of Civil Engineers.

Sawangsuriya A.,Bureau of Road Research and Development | Ketkaew C.,Tak Office of Highways | Sramoon W.,Mahanakorn University of Technology
Geotechnical Special Publication | Year: 2012

A compaction quality control (QC) in highway construction in Thailand is typically based on an in-place density measurement using the sand replacement method. Although monitoring compaction quality through a sand cone density test is relatively simple, such method is generally time consuming, labor intensive, less cost-effective, and destructive. This paper presents the laboratory evaluation of an innovative QC tool called the soil density gauge (SDG), which provides rapid and instantaneous measurement of density and moisture content based on the electrical impedance spectroscopy. The SDG was evaluated in a test box. Six highway materials were used in the study. The variation of SDG measurements along with its measurement characteristics was investigated herein. The paper also compared the SDG density and moisture content measurements with other tests such as the nuclear gauge, the soil stiffness gauge, and the sand cone method etc. © 2012 American Society of Civil Engineers.

Lertworawanich P.,Bureau of Road Research and Development | Karoonsoontawong A.,King Mongkut's University of Technology Thonburi
Transportation Research Record | Year: 2012

Pavement markings are one of the most important highway assets. Good pavement markings provide good visibility for traffic, whereas poor pavement markings can adversely affect traffic operations on highways. However, a limited amount of research has been conducted on the effects of working conditions on the service life of pavement markings. This paper presents duration models for retroreflectivity of thermoplastic pavement markings in Thailand. This approach allows the service life of pavement markings to follow probability distributions in which model parameters are assumed as a function of relevant independent variables such as traffic volumes. The maximum likelihood estimation technique was used to estimate means and standard errors of the model parameters. Retroreflectivity data of thermoplastic pavement markings were collected from the eastern highway network of Thailand, which consists of more than 5,000 km of highways in various traffic conditions. The analysis results showed that traffic volumes had negative effects on the service life of the pavement markings. This paper proposes a preemptive goal program for approximating required budgets to ensure the maintenance of the percentages of good condition pavement markings over the planning horizon. The first-priority goal is to maintain the percentage of control sections that are in good condition, and the second-priority goal is to minimize total maintenance costs. In the illustrative example, the inconsistency between the Thailand Department of Highways' specifications and field practices caused estimated required annual budgets and the deterioration of pavement markings to greatly fluctuate over the planning period. For more consistency between specification and field practice, the proposed models will be applied in a pavement marking management system.

Dechasakulsom M.,Bureau of Road Research and Development | Sukolrat J.,Bureau of Road Research and Development | Sawangsuriya A.,Bureau of Road Research and Development
Geotechnical Special Publication | Year: 2012

Department of Highways (DOH), Thailand has been using reinforced earth structures for road embankments and bridge abutments for nearly a decade. Different methods of earth reinforcement, i.e., reinforced steep slopes (RSS) and mechanically stabilized earth walls (MSEW) are commonly selected based on flexibility and steepness of the slope. Different reinforcing materials consisting of extensible materials (e.g. polypropylene, polyethylene, and polyester) and inextensible materials (e.g. steel wire grid and metallic strips) were investigated for their engineering properties such as strength, elongation, and pullout resistance, while backfill materials were a mixture of lateritic soils and sand to conform with the DOH standard. To investigate the effects of different reinforcing materials for construction, a trial embankment of 15x18m2 and 6m high incorporating three RSS sections and two MSEW sections were constructed and elaborately monitored using strain gauges, settlement plates, and inclinometers installed in several layers. Field monitoring results revealed the behavior of the trial embankment during construction and after load applications. The result from this study will be beneficial for future implementation of reinforced earth structure embankment. © 2012 American Society of Civil Engineers.

Lertworawanich P.,Bureau of Road Research and Development | Dechasakulsom M.,Bureau of Road Research and Development | Aursudkij B.,Bureau of Road Research and Development
53rd Annual Transportation Research Forum, TRF 2012 | Year: 2012

In the second half of 2011, Thailand has recently faced with the most devastating flood of her modern history. More than 3,330 national highways are damaged by this flood. Some roads are heavily destroyed while others are partially damaged and emergency relieves cannot access to the flooded areas. Highway restoration is an urgent responsibility of road authorities. This study presents the sequential highway network restoration decision model where highways are restored one by one in sequence. To determine an optimal restoration sequence, the model is formulated as a dynamic program where the primary objective is to sequentially restore roadways to minimize the travel demand loss for the disconnected network. Once the network is connected, the secondary objective is to sequentially restore roadways to minimize the network travel time where traffic assignment onto the network is based on User Equilibrium concept. A sample network is examined to investigate the solution characteristics. It is found that the proposed algorithm can provide good practical solutions to the sequential highway network recovery problems. © (2012) by the Transportation Research Forum All rights reserved.

Ponlathep L.,Bureau of Road Research and Development
IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC | Year: 2010

Traffic signals are the main devices for controlling traffic to guarantee the safe crossing of opposing streams of vehicles and pedestrians. In this study, a simple cycle and split optimization method is developed for isolated intersections. The split optimization is based on the notion of minimizing delay per cycle while cycle length is adjusted according to the residual queues at the end of the cycle. Traffic dynamics at signalized intersections are represented on time-space diagrams using the shockwave theory and information from detectors installed upstream of intersections. Splits are incrementally adjusted so that the delay per cycle is gradually diminished. Cycles are modified to have an efficient use of the provided green times without causing the residual queues. Unlike most algorithms, the proposed method can manage traffic even when queues extend beyond detector locations. Simulation experiments on a two-one-way intersection with different demand scenarios are performed to demonstrate efficiency of the developed algorithm. Hypothesis tests are conducted to statistically verify the efficient comparison between the proposed method and the Webster formula. It is found that in case of fixed demand the proposed method can optimize splits and cycle lengths with no worse performance measures than the optimal fixed-time signal settings according to the Webster formula. For the variable demand case, the result indicates that the algorithm can adjust splits and cycle lengths in response to the change of demand and provides better performance measures than the Webster formula. ©2010 IEEE.

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