Evaluation of Rainfall Infiltration and Compaction Effect on Soil-Geogrid Interaction Behavior

The geogrid-reinforced soil structures play important roles in the reinforcement applications since 1980s. Generally in design of the geogrid-reinforced soil structures, the soil-geogrid interaction behavior is not directly considered. Instead, the interaction strength is represented by the consolidation drained strength of soil commonly. However, neglecting the effect of compaction and suction on enhancing soil strength in design possess great conservativeness, leading to the waste in engineering practice. Moreover, along with providing appropriate drainage, the effect of water presence on stability of reinforced soil structures is not specially considered in design. As a result, reinforced soil structures have the possibility to failure caused by rainfall even totally following design code. Therefore, a trend considering the compaction effect and suction influence on the soil structure's behavior has arisen. For such trend, soil-geogrid interaction behavior need to be carefully investigated paying attention to the infiltration to avoid failure due to the rainfall. In this research, improved pullout tests capable of simulating in-suit rainfall infiltration are conducted considering the influence of rainfall infiltration and compaction. In order to survey the infiltration effect on interaction behavior, the pullout behavior of infiltrated soil samples are compared with the pullout behaviors of dry soil sample and soil sample with optimum water content. And the soil samples in pullout test are prepared in different degree of compaction paying attention to the compaction effect. The test results demonstrate that the infiltration dramatically reduces the pullout strength of soil-geogrid interaction. Meanwhile, the compaction could not mitigate the harm of infiltration on the pullout strength although it is able to enhance the peak pullout strength obviously.