Effect of Climate Conditions on the Cracking of a Highway Retaining Wall Supported in the Active Zone

In this study, the causes of distress (cracks and joint movement) on the face panels of an 244 m (800 feet) long and 4.6 m (15 feet) high retaining wall supporting a highway embankment was investigated by instrumenting the ground in front of the wall. The foundation of the retaining wall was placed in a CH soil few feet below the surface and ground water table was about 7 feet (2 m) below ground. In order to determine the vertical and horizontal ground movements in the active zone and to determine the variation of matric soil suction adjacent to the wall total of three boreholes were instrumented. Also changes in temperature and rainfall were also monitored during the study period. The ground and wall crack movements were measured for about two years which included also the hurricane Ike. The instrumentation included tensiometers, extensometers and an inclinometer. Based on the measurements over period of one year, largest vertical and horizontal displacements were observed in the top five feet of the ground. The tensiometer was used to measure the matric suction pressures during this period. The change in the length of the crack opening varied with the climate and it was similar to the settlement in the active zone. Typical measured changes in the crack along the wall varied from 0.2 mm (opening) to –0.4 mm. Effect of climate changes on the distress of retaining wall was also evaluated using the Thornthwaite moisture index (TI). TI was also used for to predict the suction pressure in the ground.