An approach to quantify nonuniformity of compacted earth materials using spatially referenced rollerintegrated compaction measurements and geostatistical analysis is discussed. Measurements from two detailed case studies are presented in which univariate statistical parameters are discussed and compared to geostatistical semivariogram modeling parameters and analysis. The univariate and geostatistical parameter values calculated from the roller-integrated measurements are also compared to traditional spot test acceptance criteria. Univariate statistical parameter values based on roller-integrated measurement values provide significantly more information than traditional point measurements, while geostatistics can be used to identify regions of noncompliance and prioritize areas for rework.
KeywordsStatistics, Geostatistics, Soil compaction, quality control, earthwork, intelligent compaction, semivariogram, measurement
Disciplines
Geotechnical Engineering | Statistics and Probability
CommentsThis is a post-print of an article from Journal of Geotechnical and Geoenvironmental Engineering136, no. 6 (2010) Abstract: An approach to quantify non-uniformity of compacted earth materials using spatially referenced roller-integrated compaction measurements and geostatistical analysis is discussed.
Roller-integrated compaction monitoring (RICM) technologies provide virtually 100-percent coverage of compacted areas with real-time display of the compaction measurement values. Although a few countries have developed quality control (QC) and quality assurance (QA) specifications, broader implementation of these technologies into earthwork construction operations still requires a thorough understanding of relationships between RICM values and traditional in situ point test measurements. The purpose of this paper is to provide: (a) an overview of two technologies, namely, compaction meter value (CMV) and machine drive power (MDP); (b) a comprehensive review of field assessment studies, (c) an overview of factors influencing statistical correlations, (d) modeling for visualization and characterization of spatial nonuniformity; and (e) a brief review of the current specifications.
An intelligent compaction (IC) specification that required variable feedback amplitude control was recently implemented on the TH-64 reconstruction project in Minnesota. At this site, IC and in situ measurement values were collected to characterize the empirical relationships and variation associated with each measurement value, ultimately to develop a process that better describes the geospatial nature of the data. A geographic information system database was created with IC measurement values and parallel quality assurance data to demonstrate one method for managing large quantities of data. Spatial geostatistics were also examined by using variogram modeling for characterizing uniformity. The findings from this study provide guidance on implementing IC specifications regarding effective use of the technology and some of the challenges that still remain.
The quality of constructed pavement foundation layers was studied with rapid and near-continuous soil stiffness measurements as alternatives to traditional nuclear gauge moisture–density measurements. Sixteen sections of stabilized pavement foundations covering 4.8 mi, with ground conditions ranging from soft to very stiff, were studied. Measurements from falling weight deflectometer, light weight deflectometer, dynamic cone penetrometer, and roller-integrated compaction monitoring systems were used to assess soil stiffness. Statistical analyses of the results were reported in the form of coefficient of variation and empirical correlations between measurements. Results of soil stiffness were compared with two independent groups of nuclear moisture–density measurements to demonstrate some of the shortcomings of traditional nuclear-gauge testing for quality assessment. The findings from this paper show the value in using soil stiffness measurements to characterize ground variations. Cost data are also reported for the stabilized sections.
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