The design institute Soyuzdorproject OAO specified installation of a soil reinforcement geoplatform in a troubleshooting section on weak soils (very soft clayey silt of grey colour shaped as a pocket of depth varying from 5 m to 10 m, E=0.45 MPa). The geoplatform comprised 5 layers of Geospan GCP 30/20 volumetric geogrid encased by Geospan GT PP 80 strong woven geotextile.
An analysis of the troubleshooting section (stakes 24+00 and 25+50) and the soil-reinforcement geoplatform technical and economic effectiveness was carried out by Soyuzdorproject OAO aided by Gexa engineers. The analysis was assisted by the geotechnical calculation program PLAXIS (simulation of soil-reinforcement embankment structures on weak foundations by finite element method). The results of the soil-reinforcement embankment calculation showed:
- a decrease in settlement by 56 cm (54%) as compared to the embankment settlement without reinforcement and in deformation irregularity;
- slope stability coefficient growth from 1.18 to 1.72 with the required value of 1.3. The soil-reinforcement embankment stability is ensured with a margin of 35% with Geospan geoplatform used;
- consolidation period shortening by 44%.
No deviation from the Procedures for geosynthetics laying was identified in the course of the geoplatform installation by SU-920 DSK Avtoban OAO in June 2014. Quality control of Geospan geosynthetics supplied to the project was supervised by representatives of Gexa – Nonwoven Materials OOO.
As of April 2015, no deformation of the troubleshooting section subgrade and surface was encountered, Soyuzdorproject OAO intends to monitor the site in June 2015 and provide an inspection report.
