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Hi Everyone, The site consists of 5 to 6 m of very loose to loose liquefiable sand over bedrock with high groundwater. Will you consider drilled shafts or H piles for this site? The loadings of the building are relatively high and it’s somewhat sensitive to settlement And what should be...

Thank you ErieChch. Can anyone else share their thoughts. The question is basically about effect of closely spaced joints on bearing capacity. Thanks

Hi Everyone, There are various tables and formulas for bearing capacity of rocks. However they give very different numbers ranging from 3 MPa to 35 Mpa for the site that I am working on. 35 MPs is not a reasonable number to me but want to hear other opinions. The methods used are as simple of...

Hi Everyone, if a site with loose saturated sand and silt requires dewatering for construction, can dewatering be considered as a soil improvement method? Can bearing capacity, liquection resistance and soil parameters be increased provided that boreholes are drilled after dewatering to verify...

Thanks for the detailed response. The difference in lab requirement is interesting. It appears that for poor rocks it’s better to get larger core but if the rock quality is good, NQ may be enough. One article was saying RQD should be based on a diameter more than 54 mm, but I see many...

I used winlog in the past and it was easier and generally better than Gint. Not sure if winlog still around though.

Hi everyone, what are limitations of NQ coring for geotechnical investigations? The structure is a light weight industrial structure which will be on piles penetrating to the rock and the client want to use NQ coring. Is there any limitations in type of information or tests that can be done on...

Hello, We are going to drill some boreholes for a pipe line under a shallow lake (4 m deep max.). What kind of geotechnical testing would be the best? Is SPT practical and will give reasonable results? what about shear vane? The proposal did not include any CPT testing and we should do...

assuming the hammer is or right size, what would define "the adequate refusal criteria"? can you please elaborate.

Thanks Jayrod12, good to know the state of practice in other areas.

Thank you oldestguy, I agree. The refusal criteria is not mentioned and now the contractor is defining that. What would be good blow count for last 1"? Bedrock is Southwestern Ontario shale. and how may I make sure the tip is not on top of cobbles and boulders?

Thank you Jayrod12, do you know what could be the criteria for shale bedrock? the project is located in SW Ontario, Canada.

Hi All, I am involved in a project that piles needs to be driven to bedrock. There is a 6 ft thick layer of cobbles and boulders just above the bedrock. Piles are H-piles with shoes and the QC include recording number of blows per 10". The drawings saying using Hiley formula for ultimate loads...

Hi All, I am planning an investigation for drilling in a relatively shallow lake (approx. 5 m of water and sediments at the bottom) to obtain permeability of bedrock. The rock will be in saturated condition and under head of water. To do packer test, some references are saying we should do...

Hi All, I am going to do packer tests to get permeability of rock below a small lake (approximately 5 m of water above the surface of bedrock). The drilling and test will be done from a barge. When I look at text books, I see below groundwater level a pump out test is better than a pump in test...

Thank you all, great points, oldestguy- I fixed the dimensions and slope- it was 7.5 m, thanks for noting the mistakes GeoEnvGuy- Great notes, the drilling was done last year, still showing soft clay, whatever consolidation happened, is reflected in the results. In fact, a thin top layer is...

Thanks Fattdas, I like the step 1 to 3 that you mentioned.

Hi All, Could you please share your thoughts about this project. The culvert and embankment was built few decades ago. The embankment is 7.5 m high and relatively steep at some areas, generally 1V:1H to 1V:2H. The underlying soil below embankment, problematic! : Soft Clay, SPT N=0 (sinking...

Thanks Mad Mike, great post. I will open another tread about increase in frequency of landslides in our area, please share your thoughts there as well. Thanks!

Thank you oldestguy and ErieChch, great comments. I think I have clear view now ad can proceed.