Required Geotechnical Testing 1

[black knight]

Hi everyone,
A newbie here.
There is a project wherein we need to design a conveyor which would run from the ground surface and slopes down until everything is under the ground. it will be protected by concrete walls and slabs along its length.
There is also a portion wherein the conveyor will run under an existing roadway thus there is a need to design a concrete cover suitable to withstand heavy truck loadings.

my question is: what geotechnical test needs to be carried out in order to design the concrete?
thanks.

 

[oldestguy]

While we have many experts here that can answer, but I'd think your best approach would be to take on a geotechnical engineer firm to review your job and make recommendations for what to investigate and test.. This usually involves on-site test borings and sampling and possibly a series of laboratory soils tests. Then a report with detailed recommendations for your design and construction comes from these phases. They may or may not have their own field services, but those are easily contracted and over-seen as they do the investigation. As the field work is done there may be the need to change the investigation some, depending on what is found. You don't just ask a drilling firm for borings without an experienced geotechnical engineer supervising them.

 

[black knight]

Thanks, @oldestguy.

I have spoken to one of the geotechnical-service provider in my area and one of the tests they recommended was CPT to determine the allowable soil bearing capacity. I'm also thinking the same thing but do you think this test is enough knowing that the loading involves dynamic and heavy loadings? I am also thinking about the settlement - would they be able to recommend some capacities from a given allowable settlement from a cone penetrometer test alone? we don't have a lot of budget for soil investigation so we're trying to squeeze all the information we can get from a single test.


thanks and in advance.

 

[EireChch]

"We don't have a lot of budget for soil investigation" - that could be your famous last words...

You're dealing with a serious enough development...tunnelling beneath a road. If it was a residensrial development I'd say fair enough but not for what you are doing. I understand that there wil always be budget constraints but You need to do a comprehensive investigation. Time and time again developers cut corners on geotech and it comes back to bite them.

CPT is a good test as it provides a continuous strength provider with "interpretated" soil type. If you have any gravel layers though it may not penetrate. I think CPT testing would only be used to supplement boreholess with sampling and lab testing.

As OG suggests, it should be your geotechnical providing all advice but to get more meaningful answers more info would be needed. What is the geology, how long is the conveyor, how steep is the slope, how deep do you need to go beneath the road etc.

Constructing the tunnel beneath the road may be your biggest concern

Good luck

 

[black knight]

Thanks to you both guys.
Your comments are so helpful. I will follow your advice and hopefully I will get to the bottom of this.
kind regards,
bk

 

[oldestguy]

As to "saving money", even though you may think hiring an old timer geotech is more costly, experience in certain areas can result in that person using index type tests to estimate things like settlement and bearing capacity values to sufficiency accuracy for what the equipment can withstand. Some tests can be very expensive and an experienced geotech may be able to avoid them.