Geotechnical Forensic Investigation of Observed Cracks on a Building in Tallahassee, Florida

In July 2010, two vapor extraction wells were installed about 15 feet from a building at an angle of 50 degrees to the horizontal using rotosonic drilling technique (RDT). In June 2011, a crack approximately 0.5 inch wide on the wall of the building was reported. Several other small cracks were observed on the building following inspection by the authors. The owner of the building expressed concerns that the rotosonic drilling was the cause of the cracks and wanted assurance that subsequent drillings would not exacerbate the problem. Geotechnical forensic investigation was performed to evaluate the potential cause(s) of cracking in the building and whether future drilling would impact the building and the foundation structure system. The investigations involved performing site reconnaissance surveys, site-specific field investigations, real-time vibration monitoring, crack monitoring, and geotechnical laboratory analyses. This paper presents the results from the forensic investigations. Based on these results, potential causes for the development of cracks in the wall of the building and recommended repair measures are discussed

General Report - Session 8

This General Report presents a summary of the eleven (11) papers accepted for the session 8 focused on Case History of Forensic-Geotechnical Engineering and Case Histories on Health Monitoring and Retrofit of Infrastructure. The session includes discussion of Reliability of Codes; Risk Analysis Pertaining to Public Structures, Non-Destructive Evaluation and Load Testing of Drilled Shafts, Auger Cast Piles and Driven Piles, and Damage Evaluation; Advance Information, Systems in the Geotechnical Risk Predication and Assessment. The papers originate from eight countries and cover an array of important topics in the area of forensic and geotechnical engineering. These include case histories; geotechnical-forensic engineering investigation of structures; probabilistic three dimensional modeling; behavior of laterally loaded piles; failure of helical anchors; working pile load tests; refurbished used of timber piles; and vibration effects on historic buildings. A list of the papers is assimilated in Table 1 by topic. The summary illustrated below will give the reader(s) a general overview of the focus of those papers and is intended to direct the reader to their area of interest. The activities of Session 8 also include case histories on health monitoring and retrofit of infrastructure, including bridges, tunnels, and other transportation and geotechnical structures, and their effects on existing facilities and buildings, and remediation. The Session 8 organizers greatly appreciate the efforts of the authors and commend the quality of the accepted papers

Field performance of geogrid reinforced low-volume pavements

textFor the past three decades, geosynthetics have been recognized as materials that can significantly improve the performance of pavements on weak subgrade. Pavements exhibit non-linear elasto-plastic behavior. The addition of geosynthetics is undoubtedly beneficial. This being said, researchers have concentrated more on lower life cycle cost and high benefit-cost ratio whereas much less attention has been given to the complex behavior of the reinforced pavement system. Comprehension of the short-term and long-term field performance of reinforced pavements under continued traffic and cyclic environmental loading has remained unexplored. There is empirical evidence indicating quantitative benefits of reinforced versus unreinforced pavement structure. However, quantification of the relative benefits of different types of reinforcement like geogrids and geotextiles lacks information. Further, evaluation of the benefits and comparison of chemical stabilization in the form of lime treatment with mechanical stabilization in the form of reinforcement for pavements on soft soils has received lack of attention. In view of this, full-scale instrumented reinforced and lime treated pavement sections with different schemes were studied. Regular Falling Weight Deflectometer (FWD) testing was conducted in a Farm-to-Market Road, in Grimes County, Texas. Three different geosynthetic products were used for base reinforcement and lime treatment was used for subbase stabilization. Deflection measurements for 9 field trips in 3.5 years were evaluated. Modified deflection basin parameters (DBPs) were defined to typically identify layer properties and were used to measure the relative damage to the base, subbase and subgrade for different sections. A modified Base Damage Index (BDI) and a modified Base Curvature Index (BCI) were defined as a part of this study to capture the benefit of reinforced base and lime stabilized subbase respectively. The variation in the DBPs over three periods of wetting and drying along with explanation of the observed trends forms a part of this research. In addition, a number of condition surveys were performed, during 3 years, to visually identify distresses in various sections. A unique distress quantification technique was developed for measuring deterioration of the pavement sections in terms of the observed distresses and FWD measurements. With this, an index of pavement performance was developed. Thus, the FWD deflection data analyses complemented by visual observation, reveals important information on performance of different geosynthetics with the same base course. Analysis of the field performance of the multiple experimental sections throws light on the relative merits of base reinforcement against lime stabilization.Civil, Architectural, and Environmental Engineerin