Rakra
Geotechnical
- Jul 7, 2010
- 21
Hi Everyone,
My site is a coastal site with the following prevalent geotech conditions (established by drilling and test pitting):
1. Sandy silt and clay, peat alluvial sequences (up to 5m depth)overlying unconsolidated sands and gravel dominate soils and also mixture of cobbles and gravels. Dominate subsurface layers are 'mixture of soil and cobbles/boulders' and Sandy gravel and gravelly Sand layers. These are intersected by discrete pockets of silty mixtures. Unconsolidated sediments persist to at least 30 to 50m below surface (limit of excavation).
2. Artesian conditions were encountered in several boreholes. Though the pressure above hydrostatic has not been measured.
3. Site is partially on-land and partially in the sea
4. Marine subsurface is sand dominate profile, SPT N values > 18
I am thinking to request for additional geophysical testing to be performed to better define the subsurface.
My question is, what are my foundation options in such cases? Some examples in literature I have come across suggest that under artesian conditions, locate foundations above artesian conditions and use spread footing on upper layer. In marine areas, drill and install open steel pipe piles.
My site is a coastal site with the following prevalent geotech conditions (established by drilling and test pitting):
1. Sandy silt and clay, peat alluvial sequences (up to 5m depth)overlying unconsolidated sands and gravel dominate soils and also mixture of cobbles and gravels. Dominate subsurface layers are 'mixture of soil and cobbles/boulders' and Sandy gravel and gravelly Sand layers. These are intersected by discrete pockets of silty mixtures. Unconsolidated sediments persist to at least 30 to 50m below surface (limit of excavation).
2. Artesian conditions were encountered in several boreholes. Though the pressure above hydrostatic has not been measured.
3. Site is partially on-land and partially in the sea
4. Marine subsurface is sand dominate profile, SPT N values > 18
I am thinking to request for additional geophysical testing to be performed to better define the subsurface.
My question is, what are my foundation options in such cases? Some examples in literature I have come across suggest that under artesian conditions, locate foundations above artesian conditions and use spread footing on upper layer. In marine areas, drill and install open steel pipe piles.