Time histories of tensile force in geogrid arranged in two full-scale high walls

Abstract

Two tall geosynthetic-reinforced soil (GRS) walls, one 16.7 m high supporting a sloped embankment, and the other 21.1 m high with a level backfill, were constructed to support the taxi way of Mt. Fuji Shizuoka Airport, Shizuoka Prefecture, Japan, which was opened to service in June 2009. As only limited residual deformation during service is allowed and high stability is required, the backfill was a well-graded gravelly soil, which was well compacted at controlled water content and reinforced with geogrid reinforcement. In the respective walls, three representative geogrid layers were fitted with a number of electric-resistance strain gauges to monitor the geogrid tensile strains during and after construction to ensure high stability and sufficient serviceability. After the wall construction had been completed, the geogrid strains were either only increasing at a very low rate, or had stopped increasing, or had started decreasing. A series of in-air tensile loading tests were performed on different geogrid types used for the wall construction to evaluate their elasto-viscoplastic properties. The time histories of tensile force in the geogrid layers were estimated from the measured time histories of the geogrid strains based on a non-linear three-component rheology model using the model parameters determined by the in-air tensile loading tests. After the end of wall construction, the estimated geogrid tensile force was either increasing at a very low rate or was decreasing with time. Even at the locations where it tended to increase with time, the estimated geogrid tensile force never increased greatly by the end of a typical design life (i.e. 50 years) from the value at the end of wall construction. As the estimated maximum geogrid force at the end of the design lifetime is substantially lower than the respective design tensile rupture strengths, it is estimated that creep rupture failure of the geogrid is utterly unlikely. The analysis suggests that these estimates are also relevant when the lifetime is 100 years. The framework to estimate the time histories of reinforcement force from the time histories of measured reinforcement strains used in this study can be applied to other similar cases.

Performance of an 11 m high block-faced geogrid wall designed using the K-stiffness method

“…It follows that the loads computed at EOC are for practical purposes the largest loads in the reinforcement for design purposes. The same conclusion can be deduced from the case study by Kongkitkul et al (2010). They recorded post-construction strain rates in a 21 m high wrapped face wall for more than 2 years and concluded that increases in strains were very small, zero, or, in some cases, even decreasing.…”

“…Other models have been proposed in the literature to convert strains in polymeric reinforcement to loads. However, these models are more complicated, have a greater number of fitting parameters, and (or) do not consider time (e.g., Ling 2003;Kongkitkul et al 2010). The model used here is much simpler.…”

Creep behavior of geosynthetics using confined-accelerated tests

“…Of these, the reduction factor due to creep is commonly the most significant. As a result, the design tensile strength becomes considerably lower than the UTS obtained from short-term tensile tests (Kongkitkul et al 2010). In addition to this approach, the creep data can also be used to determine the geosynthetic's maximum allowable strain.…”

Nonlinear load–strain modeling of polypropylene geogrids during constant rate‐of‐strain loading

“…The second model is the three‐component model for polymeric reinforcement materials described in the articles by Hirakawa et al and Kongkitkul et al . Modifications to the three‐component model are introduced to improve the accuracy of the load–strain predictions of the PP geogrid materials under the combined conditions of low strain and low strain rate.…”