Author: Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 48
Book Description
Resilient Modulus for New Hampshire Subgrade Soils for Use in Mechanistic AASHTO Design
Resilient Modulus for New Hamphire Subgrade Soils for Use in Mechanistic AASHTO Design
Author: Vincent C. JanooPublisher:
ISBN:
Category : Soil mechanics
Languages : en
Pages : 35
Book Description
Resilient Modulus for New Hampshire Subgrade Soils for Use in Mechanistic AASHTO Design
Author: Evaluation of Procedure to Estimate Subgrade Resilient Modulus for Use in Pavement Structural Design
Author: Harold L. Von QuintusPublisher:
ISBN:
Category : Pavements, Asphalt
Languages : en
Pages : 54
Book Description
The Kansas Department of Transportation (DOT) uses the 1993 DARWin version of the 1986 AASHTO Guide to design rigid and flexible pavements. One of the inputs needed for the flexible pavement design procedure is the modulus of the subgrade soils, which has an effect on the total pavement thickness. Different procedures can be used to estimate the effective roadbed resilient modulus for flexible pavement design and effective modulus of subgrade reaction for rigid pavement design. As part of the study entitled Determination of the Appropriate Use of Pavement Surface History in the KDOT Life-Cycle Cost Analysis Process, an evaluation of the procedure that Kansas DOT uses to estimate the effective subgrade resilient modulus was completed. This report provides the results of that evaluation.
Estimating Stiffness of Subgrade and Unbound Materials for Pavement Design
Author: Anand J. PuppalaPublisher: Transportation Research Board
ISBN: 0309098114
Category : Technology & Engineering
Languages : en
Pages : 139
Book Description
At head of title: National Cooperative Highway Research Program.
Measuring in Situ Mechanical Properties of Pavement Subgrade Soils
Author: David E. NewcombPublisher: Transportation Research Board
ISBN: 9780309068574
Category : Science
Languages : en
Pages : 84
Book Description
This synthesis report will be of interest to pavement and geotechnical design and research engineers, geologists and engineering geologists, and related laboratory personnel. It describes the current practice for measuring in situ mechanical properties of pavement subgrade soils. The tests conducted to measure the mechanical properties of soil strength and stiffness are the primary topics, and these are discussed in the context of design procedures, factors affecting mechanical properties, and the variability of measurements. Information for the synthesis was collected by surveying U.S., Canadian, and selected European transportation agencies and by conducting a literature search. This TRB report provides information on existing and emerging technologies for static and dynamic, and destructive and nondestructive testing for measuring in situ mechanical properties of pavement subgrade soils. Correlations between in situ and laboratory tests are presented. The effects of existing layers on the measurement of subgrade properties, and soil spatial and seasonal variability are discussed. Most importantly, the use of soil properties in pavement design and evaluation are explained. New applications or improvements to existing test methods to support the use of mechanistic/stochastic-based pavement design procedures are also explained.
Resilient Modules for New Hempshire Subgrade Soils for Use in Mechanistic AASHTO Design
Author: A Model for the Prediction of Subgrade Soil Resilient Modulus for Flexible-pavement Design
Author: Beresford O. A. DaviesPublisher:
ISBN:
Category : Pavements
Languages : en
Pages : 182
Book Description
Subgrade soil plays a very important role in the construction of roadways. Before the use of asphalt in the construction of roadway, roads were being constructed based on experience. The introduction of paving asphalt in road construction has led to the development of engineering procedures and designs for the methods of construction. The resilient modulus of the underlying material supporting the pavement is now considered as a key material property in the AASHTO mechanistic-empirical design procedure. Attempts have been made by researchers to predict the Subgrade resilient modulus from laboratory/field experimental methods based on the soil properties. This research seeks to develop a model for predicting the subgrade resilient modulus due to environmental conditions by considering the seasonal variation of temperature and moisture content which affects the soil. The limitation of this research model is that it cannot be used universally since environmental conditions vary from place to place, however, it can be modified to suit other local environmental conditions. The detrimental effect of low resilient modulus of subgrade soil is observed in the damaged analysis.
Back-calculation of Subgrade Resilient Modulus for Mechanistic-empirical Pavement Design in Wyoming
Author: Daniel K. HellrungPublisher:
ISBN: 9781321892161
Category : Pavements
Languages : en
Pages : 103
Book Description
In an effort to build more cost effective and robust pavement structures, the Wyoming Department of Transportation (WYDOT) is in the transition of adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG) instead of the 1993 AASHTO Pavement Design Guide. The University of Wyoming is currently conducting a comprehensive research study to facilitate the implementation of the MEPDG in the state. This thesis describes using a Falling Weight Deflectometer (FWD) as a non-destructive testing method for data collection and the development of a back-calculation testing protocol for estimating the resilient modulus of subgrade soils in Wyoming. During the summer of 2013, FWD testing was performed at 32 test sites throughout the state of Wyoming. Deflection measurements were collected and used to back-calculate the resilient modulus of the subgrade at each test site. The back-calculation protocol was developed by modifying the user guide of MODTAG, a back-calculation software, to achieve consistent and realistic back-calculated modulus results. Additionally, using these back-calculation results and laboratory measured modulus results for the same test site, two linear regression models were developed to correct the back-calculation results to laboratory equivalent values. The sum of square error (SSE) was used to compare the models and then select the most suitable one. The findings of this research will facilitate the MEPDG calibration which will help with the implementation of the MEPDG in the state of Wyoming.
Resilient Moduli Properties of Compacted Unsaturated Subgrade Materials
Author: Pinit RuttanaporamakulPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
According to the new Mechanistic Empirical Pavement Design Guide (MEPDG) and 1993 AASHTO flexible pavement design guide, Resilient Modulus (MR) has been used extensively as an important material property in structure design of pavement. The modulus is used as the primary input parameter to determine the stiffness parameters and constitutive behavior of pavement components. The system of pavement basically consists of the layers of surface, base, subbase (optional), and subgrade. The compacted subgrade soils supporting pavement structure are typically unsaturated with degrees of saturation varying from 75% to 90%. The effect of unsaturated soil behavior on the mechanical properties of compacted pavement materials become an important variable and need to be considered. The main purpose of this study is to study the resilient moduli properties of compacted and unsaturated subgrade materials and to determine the effect of compaction moisture content, which is related to matric suction of the soils, on the resilient moduli properties. The second objective is to study the use of MEPDG models to calibrate resilient moduli properties either as a function of moisture content or soil suction variables. To accomplish these objectives, soil specimens were prepared at five different moisture content and dry density conditions and tested using conventional resilient modulus testing as per AASHTO T-307 procedure. The basic soil tests such as grain size distribution, Atterberg's limits, and standard proctor compaction were initially performed. Then, the advanced soil tests consisting of soil water characteristic curve (SWCCs), unconfined compressive strength (UCS) test, and conventional resilient modulus test were conducted. The soil suction conditions of the prepared specimens were determined based on the SWCCs information and the compaction moisture content. The test results indicate that compaction moisture content affected the values of resilient modulus of the subgrade soils. The specimens compacted at dry side of optimum moisture content (OMC) showed higher values of resilient modulus compared with the specimens compacted at OMC and wet side of OMC. The testing data were also analyzed with the models provided in MEPDG program. The level 2 input for predicting SWCCs provided in MEPDG gave the predicted SWCCs in similar trend to the measured SWCCs. However, the curves were not quite well matched. Lastly, the modified universal model and the model proposed by Cary and Zapata (2010) were studied and analyzed in detail. The results showed that the universal model is well suited for predicting the resilient modulus of the subgrade soils. However, the resilient modulus values predicted by the model of Cary and Zapata, sometime, showed the higher values than measured results especially, the specimens compacted at 0.8OMC.