A model to predict expansive clay roughness in pavements with vertical moisture barriers /
Expansive soils exhibit volumetric changes when subject to changes in water content. These soils are responsible for cyclic distortions in highway pavements resulting in a loss of riding comfort and road-holding ability. The distortion of the pavement surface is measured as roughness. The Texas Depa...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=730293821&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Expansive soils exhibit volumetric changes when subject to changes in water content. These soils are responsible for cyclic distortions in highway pavements resulting in a loss of riding comfort and road-holding ability. The distortion of the pavement surface is measured as roughness. The Texas Department of Transportation has installed moisture barriers in several pavement sections across the state which had a history of pavement distortions due to expansive clay movements. Data collected from ten different locations in three different climatic regions in Texas are presented. A simple model to predict the vertical movement was developed. Models were developed to predict the pavement roughness by employing regression analysis on roughness data collected from test sites and correlating regression constants to the vertical movements estimated from the vertical movement model. Models developed were assembled in the computer program PRES. The program estimates the depth of a vertical moisture barrier required to meet the designer's target level of pavement roughness. It also calculates the roughness development in pavements as a function of time. The program simulates the field conditions by accounting for the climatic, lateral drainage and longitudinal slope conditions, subgrade soil properties, structural properties of the pavement, and traffic. Roughness reduction my a darner depends upon many parameters which include Thornthwaite Moisture Index (TMI), Suction Compression Index (SCI), depth of active zone (Z[]), depth of the barrier, traffic, and structural properties of a pavement. The sensitivity analysis showed that the reduction of roughness by a barrier was more than 50% in some cases. The maximum reduction in roughness occurred at TMI of -10. The reduction in roughness increased as the SCI and Z[] increased. Also, the barrier depth required to meet a target level of roughness increased as the SCI and Z[] increased. The maximum required depth of a barrier occurs at TMI of -10. |
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| Item Description: | Vita. "Major Subject: Civil Engineering". |
| Physical Description: | xiii, 275 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 135-142). |