Estimated and Measured Settlements of Shallow Foundation Supporting Bridge Substructure

Shallow foundations have numerous advantages when compared to deep foundations; primarily: low cost, fast construction and being environment friendly. Shallow foundations on soils are underutilized to support highway bridge substructures. This is due to a limited performance data and overestimation of settlements. Despite the success of previous shallow foundation studies, more research is needed to evaluate the performance of shallow foundations as a highway bridge foundation. To study the field performance of shallow foundations on soil, the central pier footing was instrumented and monitored during the construction of a two-span highway bridge in Columbus, Ohio. A-2-4 and A-3a soil types were encountered in a borehole. The field instrumentations consisted of multiple sensors and stations for recording contact pressure under the footing, settlement of the footing and tilting of pier columns tied to the footing. A USGS quality benchmark was incorporated to establish a solid permanent benchmark at the site. The field performance data collected in the study provided further insight into how contact pressure, footing settlement and column/wall tilting were correlated with each other throughout various construction stages. The study also produced outcome on general reliability of the settlement prediction methods outlined in the AASHTO LRFD design specifications and provided enhancement to the elastic half-space method

Desempeño a largo plazo de secciones de pavimentos existentes de concreto asfáltico

RESUMEN: Los pavimentos de carreteras están diseñados para soportar las cargas proyectadas del tr·Æ co y a la vez proporcionar alta calidad para los niveles de servicio. Las grandes cargas que los pavimentos experimentan durante su existencia en conjunto con las condiciones variables de clima y humedad aceleran el proceso de deterioro y podrían causar fallas prematuras a los pavimentos. En esta investigación se realiza un estudio de patología para evaluar el desempeño actual de varios concretos asfálticos. La condición estructural de secciones de concreto asfáltico, localizados en el Estado de Ohio, Estados Unidos, se realizan por medio del método de ensayo del DeØ ectómetro de Impacto (FWD). La interpretación de los ensayos con FWD permite la evaluación de potenciales rehabilitaciones a corto y mediano plazo. La metodología de análisis e interpretación de resultados presentados en este artículo para el caso de los 110 km de pavimento de concreto asfáltico en el Estado de Ohio, se muestra como una técnica valiosa en el caso colombiano para determinar, con mediciones reales de campo, la condición y potencial rehabilitación del sistema de infraestructura que se requiere para garantizar el desarrollo económico sostenible del país.ABSTRACT: Highway pavements are designed to withstand the projected trafÆ c loads while providing a high quality level of service. The large loads that pavements experience during the design life in conjunction with variable climate and moisture conditions accelerate the deterioration process and might cause premature failure of the pavements. In this research, a forensic study to assess the current performance of several asphalt concrete (AC) pavements is conducted. The structural condition of the AC sections, located in the State of Ohio, United States, was determined by means of the Falling Weight DeØ ectometer (FWD) testing method. The evaluation and interpretation of the FWD tests permit the assessment of potential short or medium-term rehabilitation projects. The methodology of analysis and data interpretation presented in this paper for the case of 110 km of asphalt concrete pavement in the State of Ohio, stands as a valuable technique in Colombia to determine, with actual Æ eld measurements, the condition and potential rehabilitation of the infrastructure system that is required to guarantee the sustainable economic development of the country

Thermal–mechanical modelling around the cavities of underground coal gasification

Underground coal gasification (UCG) is an efficient method for the conversion of the deep coal resources into energy. This paper is concerned with a feasibility study of the potential of deeply lying coal seams (>1200 m) for the application of UCG combined with subsequent storage of CO2 for a site located in Bulgaria. A thermal–mechanical coupled model was developed using the ABAQUS software package to predict the heat transfer, the stress distributions around the UCG and the consequent surface subsidence. Material properties of rocks and coal were obtained from existing literature and geomechanical tests which were carried out on samples derived from the demonstration site in Bulgaria. Three days of gasification has been simulated by assigning a moving heat flux on a cell of 2 m × 2 m × 2 m at a velocity of 2 m/day. Results of temperature and stress distribution showed that the developed numerical model was able to simulate the heat propagation and the stress distribution around cavities under a thermal–mechanical coupled loading during the UCG process. Also, the surface subsidence was found to be 0.08 mm after three days of gasification for the case studied. It is anticipated that the results of this paper can be used for the prediction and optimization of the UCG process in deep coal seams

Condition Evaluation of In-service Chemically Stabilized Subgrades in a High Sulfate Environment

State Job No. 135443This project included measurements of strength properties, soil properties, and chemical content of natural and chemically stabilized subgrade soil from five projects across Ohio, three from sites that have historically had high sulfate content, and two that have not. The objective was to compare the properties of the soils from the sites and determine if there were crystals of ettringite or thaumasite in the soil, which would indicate potential for heaving. Site testing included PSPA, FWD, LWD, DCP, SPT, an informal distress survey, and collection of soil specimens for laboratory analysis, which included standard soils tests (Grain size, Atterberg limits, organic content, moisture content, pH, and sulfate content as determined in Ohio Supplement 1122), and chemistry analysis comprising neutralization potential, and X-ray diffraction. In the control sections, measured sulfate levels were low in the natural subgrade and higher in the stabilized subgrade but still below the criterion of concern at 3000 ppm. In the high sulfate sections, natural subgrade had still higher sulfate content, but still usually below 3000 ppm, while the stabilized subgrade generally had content above 3000 ppm, but no more than 6500 ppm to 9500 ppm depending on the site. However, the X-ray diffraction found no measurable quantity of ettringite or thaumasite crystals, indicating that conditions for formation were not met at any of the sites. The pH of stabilized soil at all locations was just above 10, which was one condition that was met. None of the pavements showed any signs of damage due to sulfate heaving. The continued practice of global stabilization of subgrade soil is recommended. The undercut section on LAK-2 showed less variability than the other section, and this approach may be considered where cost effective

Re-rounding of deflected thermoplastic conduit. Phase 2

Final report; Sponsored by: Ohio Department of Transportation; State job Number 135670 ; Project ID number 106174 ; Contract or Grant No. 30791; Sponsored by: Ohio Department of Transportation; State job Number 135670 ; Project ID number 106174 ; Contract or Grant No. 30791; "Final report, June 2021."; Includes bibliographical references (Final report, pages 86-88)Final report (x, 112 pages) -- Fact sheet (2 unnumbered pages)Re-rounding is a technique for remediating excess deflection in a thermoplastic pipe using a pneumatic device vibrating along the vertical axis and pushing against the inside crown and invert to restore the original pipe shape and redistribute the surrounding backfill. Since the process has not been evaluated on HDPE pipe outside a couple older reports, and the method is routinely used by contractors to remediate deflected thermoplastic pipes, ODOT wanted to evaluate the technology as a lower-cost alternative to removal and reinstallation of deflected pipes. Three 36 in (0.9 m) HDPE pipes were installed in ODOT Structural Backfill Type 1 (Item 304 aggregate), 2 (sand), or 3 (AASHTO #57 aggregate), and two 18 in (0.45 m) pipes were installed in Type 2 and 3 backfill. Pipes were intentionally installed with substantial deflection (10% or more) and then re-rounded by a vendor. The pipe conditions were measured and monitored by collecting profiles, measuring vertical deflections, monitoring soil pressures, soil stiffness, acceleration of soil particles (peak particle velocity), backfill characteristics, and depth of pipe corrugation before and after re-rounding. Re-rounding successfully reduced vertical deflections in all cases, though not always enough to meet the current serviceability criterion. The pipe in Item 304 backfill were the most resistant to re-rounding, going from -13.91% deflection to -8.62% after three passes with the device. The two pipes in Type 2 backfill (sand) responded better after two passes of the device (-9.89% to -8.57% for the 36 in (0.9 m) pipe and -14.50% to -7.47% for the 18 in (0.45 cm) pipe). Pipes in Type 3 backfill (AASHTO #57 aggregate) were much easier to re-round, taking only one pass of the device to go from -10.18% to -2.52% for the 36 in (0.9 m) pipe and -16.67% to -6.17% for the 18 in (0.45 m) pipe. Pressure data were consistent with redistribution of backfill particles, particularly fine

Other title: Detection of segregation in asphalt concrete pavement

"June 2021."; "Final report."; Includes bibliographical references (pages 38-41); Final technical report; Sponsored by Ohio Department of Transportation, Office of Statewide Planning & Research ; PID: 111441 ; SJN: 136126 ; Agreement #34657 (Task 1)Segregation in asphalt pavement can manifest either as variation in the gradation of the aggregate in the asphalt mix (gradation segregation) or as variation in the temperature (thermal segregation), and both may occur together. Perhaps the primary cause of segregation is improper handling during mixing, transportation, and placement of the asphalt, which can occur at the silo or at the end of the load or elsewhere in the paving process. This report includes a literature review, national survey of state DOTs, and review of construction and materials specifications to assess the current state of the practice in mitigating segregation in asphalt pavement. Recommendations for possible implementation are give

Pavement performance testing

"December, 2001."; Includes bibliographical references.; Final report.; Prepared in cooperation with Ohio Department of Transportation and U.S. Department of Transportation, Federal Highway Administration under state job no.; Harvested from the web on 1/13/06The objectives of this study were to evaluate the effects of aggregate gradation and polymer modification on rutting and fatigue resistance of Superpave mixes. Asphalt mixes were prepared using three different gradations (above, through, and below the restricted zone) and three PG 70-22 binders (unmodified, SBS and SBR modified), and were evaluated using a triaxial repeated load test, a static creep, the Asphalt Pavement Analyzer, and the flexural beam fatigue test. When aggregates meeting Superpave angularity requirements was used, the effects of gradation on the rut and fatigue resistance of Superpave mixes were relatively small and the effects of the restricted zone was not significant. Even though binders used in this study had similar dynamic shear moduli, mixes containing polymer modified binders showed significantly lower resilient moduli than the unmodified mixes when measured in the indirect tensile and triaxial compressive modes. All laboratory test results indicated that the polymer modified mixes were significantly more rut resistant and fatigue resistant than the unmodified mixes with the same PG grading. Improvement in rut resistance due to polymer modification was shown to be most significant in the triaxial repeated load test, especially at a higher-temperature. Accelerated Pavement Load test results showed the similar trends regarding rutting performance. At higher test temperature or at a fast wheel speed, mixes with polymer modified binder performed better than mixes with an unmodified binder.The objectives of this study were to evaluate the effects of aggregate gradation and polymer modification on rutting and fatigue resistance of Superpave mixes. Asphalt mixes were prepared using three different gradations (above, through, and below the restricted zone) and three PG 70-22 binders (unmodified, SBS and SBR modified), and were evaluated using a triaxial repeated load test, a static creep, the Asphalt Pavement Analyzer, and the flexural beam fatigue test. When aggregates meeting Superpave angularity requirements was used, the effects of gradation on the rut and fatigue resistance of Superpave mixes were relatively small and the effects of the restricted zone was not significant. Even though binders used in this study had similar dynamic shear moduli, mixes containing polymer modified binders showed significantly lower resilient moduli than the unmodified mixes when measured in the indirect tensile and triaxial compressive modes. All laboratory test results indicated that the polymer modified mixes were significantly more rut resistant and fatigue resistant than the unmodified mixes with the same PG grading. Improvement in rut resistance due to polymer modification was shown to be most significant in the triaxial repeated load test, especially at a higher-temperature. Accelerated Pavement Load test results showed the similar trends regarding rutting performance. At higher test temperature or at a fast wheel speed, mixes with polymer modified binder performed better than mixes with an unmodified binder

Re-rounding of deflected thermoplastic conduit. Phase 1

"Interim Report, March 2017"--Title page.; "FHWA/OH-2017-12"--Technical report documentation page.; Includes bibliographical references (page 8).; Phase 1 Interim report.; Sponsored by: Ohio Department of Transportation; State job No. 135322This study investigated the potential benefits of re-rounding of thermoplastic pipe, a process for reducing the deflection of installed pipes by drawing a vibrating mandrel through the pipe. A survey of state DOTs revealed that practice is used rarely, if ever, and the literature on the topic is very sparse, limited to reports on vendor demonstrations. Two contractors were contacted and results of the interviews are included. A plan for a detailed study under controlled conditions and in the field is presented

Other title: Implementation of Structural design methodology for spray applied pipe liners

Final report; Additional information provided in email: SJN 136124; "Contract or grant no.: Agreement #34652 (Task 4)"--[Technical report documentation page]; "August 2022."; Page numbers identified as "Page x of 31"; last numbered page is 29; Includes bibliographical references (page 29)A recently completed pooled fund study report on the structural design methodology of spray applied pipe liners [Najafi et al., 2021] was reviewed. The objective was to take a very lengthy and detailed report and determine how the findings could be applied via a more concise document. The research team reviewed in detail the laboratory study, field study, finite element model, and design equations. Some issues are identified and discussed, and recommendations for improvements in studying the problem are mad