No abstract

No abstract

No abstract

No abstract

Abstract. Seasonal climatic variations in subgrade soil affect pavement responses and can reduce pavement serviceability. In addition to causing shrinkage and swelling in expansive subgrade, variations in moisture suction may alter the material properties of soil, which ultimately affect pavement performance. The current study monitored the seasonal variation of subgrade moisture content, rainfall, and pavement deformation of a section over State Highway 342, in Dallas, Texas. Moisture sensors were installed at different depths up to 4.5 m. The soil was found to be highly plastic clay (CH) in the selected site. In addition to acquiring real-time moisture data from sensors, geophysical testing was also conducted on the slope of the pavement. Electrical Resistivity Imaging (ERI) was carried out at the slope of the instrumented pavement section to observe the moisture flow at the edge of the pavement. Based on the field monitoring data, moisture variation ranged from 5% to 14%, with higher moisture contents correlating with rainfall events. While moisture sensors provided point information, resistivity imaging yielded a continuous portrayal of subsurface moisture flow. Furthermore, rainfall-associated deformation of the pavement was monitored. Based on the monitored data, it was observed that pavement deformation varied with rainfall. A total deformation of 38 mm was recorded over the monitoring period.

Mechanically stabilized earth (MSE) walls offer simple construction techniques, pleasing aesthetics, and cost-effective solutions as an alternative to conventional gravity walls. However, design and construction should be carefully evaluated to achieve satisfactory performance of the wall. A case study is presented on a MSE wall located on State Highway 342 in Lancaster, Texas. The horizontal movement of the MSE wall was between 300 and 450 mm within 5 years of construction. A forensic investigation was performed to determine the causes of the excessive movement. It was identified that inadequate reinforcement length was one of the contributing factors that caused horizontal displacement of the MSE wall. The objective of this study was to determine the effects of soil reinforcement on excessive movement of the MSE wall. As a part of the forensic investigation, two inclinometers were installed at the site to monitor any additional movement of the MSE wall. The inclinometer results suggested that the wall continued to move at an average rate of 4.5 mm/month during the investigation period. A finite-element (FE) program was used to simulate horizontal displacement and stability of the MSE wall. It was observed that the numerical modeling results were in good agreement with inclinometer results. A parametric study was conducted to identify the effects of soil reinforcement on horizontal movement at varied wall heights and backfill conditions. Numerical analyses results indicated that the effect of reinforcement stiffness was not significant at a wall height of 4 m compared with 8 and 12 m. The wall movement varied from 74 to 29 mm for an increase in reinforcement stiffness from 250 to 42,000 kN=m at 1:0H reinforcement length. The variations in displacement with reinforcement lengths suggested that substantial reduction in displacement occurred for an increase in length-height (L=H) ratio from 0.5 to 0.7. FE modeling results were used for sensitivity analysis employing a statistical analysis program. Based on the analyses, reinforcement length and stiffness were identified as influential factors for the horizontal displacement of MSE walls at a specific height.

Recycled Plastic Pins (RPP) are predominantly high density polyethylene materials that are fabricated from recycled plastics and other waste materials. It is a light weight material and less susceptible to chemical and biological degradation. The environmental resistant behavior of RPP makes it an attractive alternative compared to other degradable structural materials. Previous study indicates that RPP was successfully utilized for slope stabilization, arch bridges and piles. The current study presents the application of RPP as a temporary lateral support of a concrete retaining wall footing on a slope. The slope is located along highway Loop 12 near Union Pacific Rail Road (UP RR) over pass in Dallas, Texas. The concrete retaining wall is located at the middle of the slope that divided it into top and bottom slope. The crest of the top slope settled as much as 30 cm and footing of the retaining wall slid away from the top slope and resulted severe cracks near a construction joint. The site investigation program indicated that the sliding of the retaining wall occurred due to lack of lateral support. As a temporary remedial measure for 1-2 years, certain sections of the slope were reinforced using RPP. The spacing of RPP at the top and bottom slope was 0.9 m c/c and 1.2 m c/c, respectively. In addition, the first row of RPP at bottom slope was installed at the edge of the retaining wall footing and smaller spacing (0.6 m c/c) was provided near the critical cracked zone to provide additional resistance. After installation, topographic survey was conducted on monthly basis to monitor the lateral displacement of the stabilized slope. The field performance results indicated that the top of the retaining wall displaced as much as 15 to 20 cm after installation of RPP. On the other hand, 4 to 12 cm displacement was observed at the bottom of the wall which was less compared to the displacement at the top. RPP at the bottom slope provided resistance against the sliding and resulted less displacement at bottom slope.

No abstract