TCVN 5729: 2007 về Freeway/expressway specification for design tập trung trình bày This specification is applied for designing new freeway/expressway outside the city, rehabilitating and upgrading highway into freeway/expressway. | 4. For the embankment section on the soft soil at the end of bridge, culvert, underpass, to avoid the unpredicted damage of abutment base, wing wall, etc. by the negative friction between embankment and abutment when base is subsiding, the base must be designed with subsidence reaching 90% of consolidation index before constructing these parts of abutment. If not, the base and other their parts must be designed in considering negative friction and propulsive forces from behind abutment when base is subsiding. These section shall be constructed as sooner as better to ensure the pre-subsidence. At the underpass, small culvert section, before excavating to construct base and culvert, it can be preloaded until the subsidence reaching the mentioned consolidation index. The minimum time for preloading is 6 month. If possible, this preloading time is as longer as better. The construction of embankment on soft soil area shall be taken as soon as possible to avoid the subsidence after opening traffic.
