Dear sir/ madam,
I was trying to classify the soil underneath up to say 20-30m, based on the value of shear wave velocity (Vs) whether it is sandy, clayey, gravel, silt etc. There are numerous test such as SPT, DCPT followed by Grain size analysis for exact classification. However, I was looking for the way to classify based on Vs. I am aware about the Vs30 method for site classification. But, I wanted to classify the soil whether the layer is gravelly, sandy, clayey and so on.
I shall be thankful to you if I could have the valuable suggestion.
Thanking you,
Sumit
Yes, I have seen some classifications of soils based on Vs, but I cannot really say whether they were universally-established standards or not now, but definitely you can find some good papers if you google it.
According to my knowledge, you can correlate the Vs to SPT values and CPT values based on studies that have been carried universally.
This book may serve as a starting point. PACIFIC EARTHQUAKE ENGINEERING RESEARCH CENTER.
However, as Janaka stated above, even if those correlation do exist, they would probably very site specific and you would have to establish your own, especially if you are looking to explicitly classify them.
http://peer.berkeley.edu/publications/peer_reports/reports_2012/webPEER-2012-08-DeJong.pdf
The shear wave velocity Vs is a measure of stiffness (G=ro*Vs^2). You can have the same stiffness from pretty different soils, e.g. coarse sand and silty clay. The difference is that for cohesionless soils the overburden pressure and the void ratio (relative density) are the controlling parameters of Vs, while for cohesive soils the overconsolidation ratio and the plasticity could have predominant influence. But for this small depths (20-30 meters) it is not a good engineering to "guess" only by the shape of the Vs vs depth diagram, because it may fluctuate significantly. You need lab measurements (at least grain-size, also Atterberg limits for clays) to say is it sandy, or clayey, or silty, or whatever it is.
Another thing that has to be accounted for is the acquisition process from site. Sensors are usually deployed inside PVC/ABS pipes installed in the borehole and the annular gap filled with bentonite and/or grout matter, both of which are bound to have an impact on the arrival times of the Vs and Vp waves.
Regards,
Aly
Dear Sumit,
to establish a classificaiton of soil based on Vs you may have to carryout an integrated geophysical survey and borehole investigation. Do various laboratory investigation and classify the soil as sand,slity,gravel and then establish relation bewtween Vs 30 using index properties.
When you go through ASCE-7 or IBC, soil layer is classified as A, B, ...., E based on measured shear wave velocity. Soil varies from place to place and the same shear wave velocity could be different types of soil composing different fraction of soil. groundwater condition and other factors influence Vs results. Soil type is classified based on laboratory testing of sample collected from particular location but the shear wave velocity reflects the entire soil column. The classification is possible if you can do something like CPT profile.
To the best of my I have not seen any code which classify soil based on shear wave velocity.Reference to ASCE-7 is mostly applicable to USA as a recommendatory process.
Dear all,
Thank you so much for all of your valuable comments. I highly appreciate it. Thank you sir Aly for the attachment. I hope your suggestions will help me to move ahead in my work.
Sumit
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Enzymology
- Enzymes