Interbedded vs Laminated (Borehole Log) 1

[ndjiji]

Hi all,

Whats the difference between laminated and interbedded when used in borehole log's description.

Is it laminated silty clay is the same meaning with interbedded silty clay?

Then, if the layer is medium dense gravel with light brown sandy Clay ; should it be written as medium dense gravel laminated with light brown sandy clay or medium dense gravel interbedded with light brown sandy clay or medium dense sandy clayey GRAVEL? which one is dominan?

TQ

 

[GeoPaveTraffic]

Descriptions should be tricky and a sheet discussing the descriptions used on a bore log should accompany the log. We have a four page sheet that discusses the descriptions used on our boring logs.

As for your specific questions: There is a difference between laminated and interbedded. To be laminated there should be distinct layers less than 0.25" thick. Interbedded is distinct layers more than 0.25" thick.

If there is both gravel and sandy clay in the strata, but the materials are not in distinct layers, then you would say medium dense gravel with light bronw sandy clay. Note that the description should include the following additional information: color of the gravel, size of the gravel, partical shape of the gravel, size of the sand, and lean or fat as a modifier to the clay.

Different firms/oragaizations use different methods to describe samples. This is why you need a definitions sheet(s) to send along with your boring logs.

Mike Lambert

 

[Ron]

Interbedded usually refers to varying rock layers while laminations or lenses refer to thin layers of one type of soil interspersed with another, such as clay lenses within sand strata.

Consider that interbedded is large scale and laminations are small scale.

 

[ndjiji]

Thank you GeoPaveTraffic for ur explanation. it helps a lot.

1. so laminated and interbedded can be used in both soil and rock?

2.i usually understand when i put the layer name as "medium dense gravel with light brown sandy Clay"<----- (i simplified this name just for an example), it would be two distinct layer of gravel and sand clay. and gravel is the primary one. am i right? but if it is "medium dense sandy clayey GRAVEL", it would mean the whole layer is mix of gravel with sandy clay is in the between the gravels/occupying voids/spaces. What do you think?


Thank you Ron, i think of the same too

But sometimes i found description of laminated SHALE as well.

 

[Ron]

You are correct in Item 2.

 

[GeoPaveTraffic]

My real point is that different engineers, geologisit, and orgainizations use different methods to describ soil and rock. Whatever method you use, you need to have a sheet that accompanies the boring logs that describes your method.

As best I can tell, I disagree with your discussion for item number 2 above. Using "with" does not indicate that there are two different layers.

While I generally dislike ASTM Standards, there is a standard for describing soils ASTM D2488. I suggest you get a copy and review it or some other published standard.

Mike Lambert

 

[charnott]

BS 5930 or its Eurocode replacement has the detailed section on precise word placement and the outline parameters for descriptors.