CHAPTER 3
PLANNING
3.1 PLANNING
In the planning, design and construction of GRS-RW, the topology, geology, related structures, surrounding environment, construction schedule and time, etc., are discussed. Based on the type, scale and significance of a project, these items are considered rationally in designing the structure.
During the stage of planning, in addition to the internal and external stability analyses, the overall layout of the structure, such as its relations with the neighboring structures, etc., are to be considered. The following items are followed during planning:
1. Topography and Geology Conditions
a) GRS-RW constructed from the RRR method uses a high-rigidity facing. If a large settlement will occur, a large stress will be concentrated at the connection between the geosynthetic layers and facing. In the case of soft ground, as to keep consolidation settlement small after facing installation (usually within 10 cm), a staged construction is employed.
b) For the ground where significantly large settlement, long-term settlement, or large secondary consolidation settlement are anticipated, the ground improvement techniques or other measures should be considered.
c) For construction along the slope, or at the site where slope failure or erosion by river is evident, a global slope stability should be evaluated.
d) For the site where water accumulates, a proper layout of drainage pipes and geosynthetics, as well as water management during construction, are required.
2. Relations with Other Structures
a) For GRS-RW constructed adjacent to the bridge abutment, differential settlement should be minimized.
b) If excavation or pile driving will be conducted inside the GRS-RW, or if construction on the structure is anticipated in the future, proper measures should be taken since these activities will affect the stability of GRS-RW.
3. Surrounding Environment
a) The construction of GRS-RW does not require heavy machinery, thus it is a beneficial construction technique at places where environmental issues, such as sound pollution or vibration, will be a concern. The aesthetic appearance of the wall can be improved by using a decorated facing.
b) If other structures are anticipated near the GRS-RW, they should be included for discussion during the planning stage.
c) If slurry or wastewater will be produced at the construction site, they should be treated according to the relevant regulations.
4. Construction Schedule and Time
a) Compared to the conventional retaining structures, GRS-RW requires a much shorter construction time. Thus, they are particularly suitable for post-disaster rehabilitation projects.
b) The stability of GRS-RW depends greatly on the compaction of backfill soil. Thus, the construction should be avoided during the period of heavy rainfall or snow. Good quality backfill soil should be used if the construction has to be conducted in the period of high precipitation.
back to contents