Calibration of Mechanistic-Empirical Rutting Model for In-Service Pavements

1998 ◽  
Vol 1629 (1) ◽  
pp. 159-168 ◽  
Author(s):  
Hesham A. Ali ◽  
Shiraz D. Tayabji ◽  
Francesca La Torre
Keyword(s):  
Plastic Deformation ◽  
Failure Mode ◽  
Good Predictor ◽  
Climatic Conditions ◽  
Empirical Models ◽  
Pavement Performance ◽  
Mechanistic Models ◽  
Design Features ◽  
Traffic Loading

Rutting is a major failure mode for flexible pavements. Pavement engineers have been trying to control and arrest the development of rutting for years. Many models are available to relate pavement rutting to design features, traffic loading, and climatic conditions. These models range from purely empirical to mechanistic models. Mechanistic-empirical models (the Asphalt Institute and Shell) were used to predict the development of rutting for 61 Long-Term Pavement Performance (LTPP) test sections. The rutting damage, calculated using these models, did not appear to be a good predictor of the observed rutting depth. A new rutting model was developed and calibrated using the data from the 61 LTPP sections. The model accounts for the plastic deformation in all pavement layers and allows the use of actual axle load and type, rather than the equivalent single axle load, in characterizing traffic.

Evaluation of subgrade and climatic zone influences on pavement performance in the Canadian Strategic Highway Program's (C-SHRP) Long-Term Pavement Performance (LTPP) study

2002 ◽  
Vol 39 (2) ◽  
pp. 377-387 ◽  
Author(s):  
Susan Tighe
Keyword(s):  
Climatic Factors ◽  
Pavement Performance ◽  
Valuable Insight ◽  
Pavement Rehabilitation ◽  
Traffic Loading ◽  
Subgrade Soils ◽  
Pavement Roughness ◽  
Subgrade Soil ◽  
Asphalt Overlays

Sixty-five sections in 24 provincial test sites received pavement rehabilitation comprising of various thicknesses of asphalt overlays, as part of the Canadian Long-Term Pavement Performance (C-LTPP) study, which was initiated in 1989. This paper describes the impacts of the various alternative rehabilitation treatments on pavement performance in terms of roughness progression under comparative climatic, subgrade soil, and traffic loading conditions. Some findings from this study include (i) in wet, high-freeze zones, thinner overlays show a higher rate of roughness progression than thicker overlays, regardless of subgrade type; (ii) in dry, high-freeze zones, roughness progression for medium and thick overlays is relatively small; (iii) in wet, low-freeze zones, thinner overlays combined with fine subgrade soils show the highest rate of roughness progression; and (iv) traffic, in terms of equivalent single axle loads (ESALs), seemed to have a limited effect on all of the above; this was attributed largely to the fact that all of the traffic essentially fell into one level, where 200 000 ESALs per year was designated as the boundary between low and high traffic levels. The methodology developed in this paper provides valuable insight into how subgrade and climatic factors influence pavement performance and can be applied to performance trend analysis of other pavements with similar climatic, subgrade, and traffic loading conditions.Key words: subgrade type, climatic zones, pavement roughness, international roughness index (IRI), Long-Term Pavement Performance (LTPP).

Accuracy of Weather Data in Long-Term Pavement Performance Program Database

2000 ◽  
Vol 1699 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Chung-Lung Wu ◽  
Gonzalo R. Rada ◽  
Aramis Lopez ◽  
Yingwu Fang
Keyword(s):  
Weather Conditions ◽  
Test Site ◽  
Climatic Conditions ◽  
Weighting Scheme ◽  
Pavement Performance ◽  
Weather Data ◽  
Climatic Data ◽  
National Climatic Data Center ◽  
Weather Stations

To provide accurate climatic data for pavements under the Long-Term Pavement Performance (LTPP) Program, a climatic database was developed in 1992 and subsequently revised and expanded in 1998. In the development of this database, up to five nearby weather stations were selected for each test site. Pertinent weather data for the selected weather stations were obtained from the U.S. National Climatic Data Center and the Canadian Climatic Center. With a 1/ R2 weighting scheme, site-specific climatic data were derived from the nearby weather station data. The derived data were referred to as “virtual”weather data. To evaluate the effect of environmental factors on pavement performance and design, automated weather stations (AWS) were installed at LTPP Specific Pavement Study Projects 1, 2, and 8 to collect on-site weather data. Since the virtual weather data were developed for all LTPP test sites and will be used for future pavement performance studies, it is essential that the derived virtual data be accurate and representative of the actual onsite climatic conditions. The availability of the AWS weather data has provided an opportunity to evaluate whether virtual weather data can be used to represent on-site weather conditions. Daily temperature data and monthly temperature and precipitation data were used in this experiment. On the basis of the comparisons made between the virtual and onsite measured (AWS) data, it appears that climatic data derived from nearby weather stations using the 1/R2 weighting scheme estimate the actual weather data reasonably well and thus can be used to represent on-site weather conditions in pavement research and design.

Long-Term Effects of Subsurface Drainage on Performance of Asphalt Pavements

2021 ◽  
pp. 036119812110326
Author(s):  
Pinyu Ji ◽  
Hongren Gong ◽  
Lin Cong ◽  
Xiaoyang Jia ◽  
Baoshan Huang
Keyword(s):  
Performance Indicators ◽  
Soil Classification ◽  
Subsurface Drainage ◽  
Climatic Conditions ◽  
Pavement Performance ◽  
Long Term Effects ◽  
Longitudinal Cracking ◽  
Long Term Performance ◽  
Term Performance

This study investigated the effects of subsurface drainage on the long-term performance of pavements. The Specific Pavement Study 1 (SPS-1) experiment of the Long-Term Pavement Performance Program (LTPP) was selected to extract performance data. Four types of cracking, rut depth, and International Roughness Index (IRI) were used as the performance indicators. Other relevant factors affecting the pavement performance were also considered: surface thickness, base type, base thickness, subgrade soil classification, total thickness, age, and climatic conditions. The significant factors to long-term performance were identified using two methods: exploratory data analyses and mixed-effects models (MEMs). Results from the analyses showed that drainage only substantially affected the transverse cracking (TC) and rutting and had little effect on the other performance indicators. Sections in the dry and non-freeze region had the best riding quality and exhibited the least alligator cracking, non-wheelpath longitudinal cracking (NWPLC), and TC, but this climatic condition worsened the wheelpath longitudinal cracking (WPLC). The use of drainage in sections from the wet-freeze (WF) region significantly retarded the development of distress. For drained sections, the base comprising an asphalt-treated base over a permeable asphalt-treated base (PATB) better sustained the smoothness and resisted rutting. For undrained sections, the asphalt-treated base was a superior alternative. Sections on sites with fine subgrade showed less WPLC, NWPLC, and TC, while those on coarse subgrade sites showed less alligator cracking and better riding quality. Sections on sites with fine subgrade showed less WPLC, NWPLC, and TC, while those on coarse subgrade sites showed less alligator cracking and better riding quality.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

DROUGHT OCCURRENCE UNDER LITHUANIAN CLIMATIC CONDITIONS

2015 ◽  
Author(s):  
Laima TAPARAUSKIENĖ ◽  
Veronika LUKŠEVIČIŪTĖ
Keyword(s):  
Meteorological Data ◽  
Standardized Precipitation Index ◽  
Vegetation Period ◽  
Climatic Conditions ◽  
Precipitation Record ◽  
Calculation Step ◽  
Drought Conditions ◽  
The Standardized Precipitation Index ◽  
June July

This study provides the analysis of drought conditions of vegetation period in 1982-2014 year in two Lithuanian regions: Kaunas and Telšiai. To identify drought conditions the Standardized Precipitation Index (SPI) was applied. SPI was calculated using the long-term precipitation record of 1982–2014 with in-situ meteorological data. Calculation step of SPI was taken 1 month considering only vegetation period (May, June, July, August, September). The purpose of investigation was to evaluate the humidity/aridity of vegetation period and find out the probability of droughts occurrence under Lithuanian climatic conditions. It was found out that according SPI results droughts occurred in 14.5 % of all months in Kaunas region and in 15.8 % in Telšiai region. Wet periods in Kaunas region occurred in 15.8 %, and in Telšiai region occurrence of wet periods was – 18.8 % from all evaluated months. According SPI evaluation near normal were 69.7 % of total months during period of investigation in Kaunas and respectively – 65.5 % in Telšiai. The probability for extremely dry period under Lithuania climatic conditions are pretty low – 3.0 % in middle Lithuania and 2.4 % in western part of Lithuania.

SELECTION WORK TO IMPROVE PRODUCTIVE AND BREWING QUALITIES OF SPRING BARLEY

1970 ◽  
pp. 38-40
Author(s):  
О. V. Levakova ◽  
L. М. Eroshenko ◽  
А. N. Eroshenko
Keyword(s):  
Protein Content ◽  
Spring Barley ◽  
Humus Content ◽  
Stability Index ◽  
Field Studies ◽  
Climatic Conditions ◽  
Extract Content ◽  
Labile Phosphorus ◽  
Loam Soil

The article presents and analyzes data of competitive varietal testing of promising varieties and lines of spring barley for yield and brewing qualities. Field studies were conducted in 2014–2017 on dark gray forest heavy loam soil. Agrochemical parameters are total nitrogen – 0.24%, humus content in a layer of 0-40 cm (according to Tyurin) – 5.19%, hydrolysis nitrogen – 123.5 mg / kg, salt extract pH – 4.92 mg-eq / 100g; labile phosphorus - 34.6 mg / 100g, labile potassium – 20.0 mg / 100g. The forerunner is winter wheat. Meteorological conditions in the years of research differed from each other and from the average long-term value. Barley samples were assessed by the protein content in the grain (GOST 10846-91), extract content (GOST 12130-77), weight 1000 grains (GOST 10842-89). Ecological plasticity was determined by the method proposed by E.D. Nettevich, A.I. Morgunov and M.I. Maksimenko, stability index (Ľ) by A. A. Gryaznov, indicator of stability level (Puss) by E. D. Nettevich and A. I. Morgunov. The main measure for assessing quality indicators is protein content. Many other biochemical and technological features of grain depend on its level. The experimental data convincingly testify to the significant influence of the soil and climatic conditions on the yield and, especially, on the brewing qualities of barley in the conditions of the Central Region of the Nonchernozem Zone. According to the studied traits, new valuable varieties Nadezhny, Sir, Noble and selection lines 141 / 1-09 h 746, 23 / 1-10 h 784, distinguished by high adaptability and resistance to adverse environmental factors, have been identified.

Use of Long-Term Pavement Performance Data to Develop Traffic Defaults in Support of Mechanistic-Empirical Pavement Design Procedures

2003 ◽  
Vol 1855 (1) ◽  
pp. 176-182 ◽  
Author(s):  
Weng On Tam ◽  
Harold Von Quintus
Keyword(s):  
Pavement Design ◽  
Vehicle Classification ◽  
Pavement Performance ◽  
Traffic Data ◽  
Design Procedures ◽  
Load Spectra ◽  
State Highway ◽  
Pavement Structures ◽  
Empirical Design

Traffic data are a key element for the design and analysis of pavement structures. Automatic vehicle-classification and weigh-in-motion (WIM) data are collected by most state highway agencies for various purposes that include pavement design. Equivalent single-axle loads have had widespread use for pavement design. However, procedures being developed under NCHRP require the use of axle-load spectra. The Long-Term Pavement Performance database contains a wealth of traffic data and was selected to develop traffic defaults in support of NCHRP 1-37A as well as other mechanistic-empirical design procedures. Automated vehicle-classification data were used to develop defaults that account for the distribution of truck volumes by class. Analyses also were conducted to determine direction and lane-distribution factors. WIM data were used to develop defaults to account for the axle-weight distributions and number of axles per vehicle for each truck type. The results of these analyses led to the establishment of traffic defaults for use in mechanistic-empirical design procedures.

scholarly journals Creating and Characterisation of New Red Clover Variety ‘Jancis’/ Sarkanâ Âboliòa Ðíirnes ‘Jancis’ Izveidoðana Un Tâs Raksturojums

2014 ◽  
Vol 68 (3-4) ◽  
pp. 180-183
Author(s):  
Biruta Jansone ◽  
Sarmīte Rancāne ◽  
Pēteris Bērziņš ◽  
Aldis Jansons
Keyword(s):  
Seed Yield ◽  
Red Clover ◽  
Climatic Conditions ◽  
Family Selection ◽  
High Dry Matter ◽  
Bright Pink ◽  
Long Stem ◽  
Dark Green ◽  
High Seed Yield

Abstract The aim of this work was to develop a red clover variety adapted to agro-climatic conditions of Latvia, suitable for different requirements of forage producers, resistant to most widespread diseases and producing high seed yield annually. Medium late ripening diploid red clover variety ‘Jancis’ was created at the LLU Research Institute of Agriculture in long-term work carried out since 1985. After free pollination of best samples of red clover collections from the VIR (St. Petersburg), individual and family selection among hybrids were carried out for approximately 20 years. Finally, best breeding line Nr. 43047 was registered as a variety ‘Jancis’. The variety is characterised by good winter hardiness, high dry matter yield (10-12 t·ha-1) and good persistence in the sward - up to 3-4 years. The variety is characterised by a long stem (90-110 cm) with 8-9 internodes, dark green leaves with a distinctive brighter picture, medium length and width of medial leaflet, and bright pink flower heads. ‘Jancis’ has stable annual seed yield in the conditions of Latvia; under favourable conditions reaching 500- 600 kg·ha-1 seeds. Since 2010, the variety ‘Jancis’ has been included in the common Latvian and EU Plant Variety Catalogue.

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