Help!!!! Please Interpret Geotechnical Investigation..

[claudelgo]

One of my proponent is telling us to do the SSRT or surface seismic refraction test, to know the rock contents of the trench we are digging for district cooling piping. Time to time he is insisting to do the SSRT as per Geotechnical Investigation on our scope of work. Can someone help me to interpret this thing, my opinion this Geotechnical Investigation is done on the start of the project,when you say Geotechnical Investigation are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions. A geotechnical investigation will include surface exploration and subsurface exploration of a site. Sometimes, geophysical methods are used to obtain data about sites. Subsurface exploration usually involves soil sampling and laboratory tests of the soil samples retrieved. Surface exploration can include geologic mapping, geophysical methods, and photogrammetry, or it can be as simple as a geotechnical professional walking around on the site to observe the physical conditions at the site.
To obtain information about the soil conditions below the surface, some form of subsurface exploration is required. Methods of observing the soils below the surface, obtaining samples, and determining physical properties of the soils and rocks include test pits, trenching (particularly for locating faults and slide planes), boring, and in situ tests.

 

[cvg]

I do recommend seismic refraction survey as a good method to supplement borings and sampling. Provides a lot of information to fill the gaps between the few locations where borings were taken. It is required by a large public agency in this region for all major underground projects.

 

[claudelgo]

when you say Geotechnical Investigation to obtain information physical properties of soil & rock around the site or to design earthworks 7 foundations for proposed structures or to be short for information for foundation design. SSRT is under the Geophysical Investigation used to obtain data about sites, so can used SSRT for this. So anyone who is good in Civil Engineering can say yes or no, because what happened this SSRT is to costly @ 2500 Saudi Rials per test, our engineer including me use our professional judgement to know if this is a rock or not. Like using the backhoe, and pneumatic rock breakers this 2 you can determine the area where you're working has a heavy present of rock layer. And this Geotechnical Investigation is in our scope of work and surveying too, so please advise...

 

[cvg]

I would leave this determination up to the civil or geotechnical engineer and the project manager to determine if it is worth the extra money to do seismic refraction in addition to borings and pits. however, in my opinion it is a quick and cheap way to gather a lot of good subsurface data. For example, if you have a pipeline running for several kilometers and you only have borings every 300 - 500 meters, there are a lot of gaps in between with no data. But for a small building foundation, might be a waste of money.