cmorgh
Geotechnical
- Dec 17, 2002
- 35
Hi to All,
There is a site where the layer texture is hard lean clay. Ground water table has not been observed down to 50 m (i.e. maximum depth of drilling). SPT has been performed for qualitative assessment of the texture as well as collecting disturbed samples (SPT values are all “refusal”). The natural moisture content is about 10 to 15 percent. Degree of saturation ranges from 60 to 70 percent. Collecting suitable Shelby (thin-wall) tube or U4 tube samples are impossible (as the layer is hard). Collecting undisturbed samples using double tube core barrel, Denison sampler or similar samplers has two main problems:
1) The samples heave inside the sampler and extracting the sample from out of the inner tubes is sometimes impossible.
2) Even if the sample could be taken out of the inner tubes, trimming them in order to get suitable size of samples for triaxial test is either very hard work or low quality trimmed samples are gained.
Studying the soil behavior for saturated condition is also a key point in this project.
I have considered some samples to be remolded and saturated for triaxial tests. Are there any other remedies for this case regarding the undisturbed sampling and saturated testing, or any way to predict the saturated cohesion? Note that due to the problem with pore-air pressure measurements, there is no way to assess the case by the theory of unsaturated soil.
Regards
There is a site where the layer texture is hard lean clay. Ground water table has not been observed down to 50 m (i.e. maximum depth of drilling). SPT has been performed for qualitative assessment of the texture as well as collecting disturbed samples (SPT values are all “refusal”). The natural moisture content is about 10 to 15 percent. Degree of saturation ranges from 60 to 70 percent. Collecting suitable Shelby (thin-wall) tube or U4 tube samples are impossible (as the layer is hard). Collecting undisturbed samples using double tube core barrel, Denison sampler or similar samplers has two main problems:
1) The samples heave inside the sampler and extracting the sample from out of the inner tubes is sometimes impossible.
2) Even if the sample could be taken out of the inner tubes, trimming them in order to get suitable size of samples for triaxial test is either very hard work or low quality trimmed samples are gained.
Studying the soil behavior for saturated condition is also a key point in this project.
I have considered some samples to be remolded and saturated for triaxial tests. Are there any other remedies for this case regarding the undisturbed sampling and saturated testing, or any way to predict the saturated cohesion? Note that due to the problem with pore-air pressure measurements, there is no way to assess the case by the theory of unsaturated soil.
Regards
