Residential Development by Marva Ellard

Geotechnical investigations underway today.

Geotechnical investigations underway today.

What does that mean?

Taking soil core samples?

Yes. Typically augering to collect split-spoon soil samples and conducting drive hammer testing to estimate shear strength of the soils encountered. Also water levels will be recorded if present.

Interesting. Thanks for posting this.

I'll keep my eye out for the design application.

Yes. Typically augering to collect split-spoon soil samples and conducting drive hammer testing to estimate shear strength of the soils encountered. Also water levels will be recorded if present.

Paseo, that's very interesting but not everyone understands your technospeak.

Sorry, basically it's collecting 18" long vertical segments of soil in a 2" diameter sleeve. The samples are typically collected a five foot depth intervals. Sampling depth is dictated by the size and type of foundation and anticipated loads. The sampling sleeve is split lengthwise. A cap on the top and a threaded ring with a beveled edge on the bottom hold the two side of the sleve together during sampling and are removed to split the sleeve and retrieve the samples.

An eight inch hollow auger is used to bore down to the top of the intended sampling zone. With the auger still in the ground, a plug (to prevent the hollow stem of the auger from filling with soil as the auger is advanced) is removed from the bottom of the auger. The sleeve is attached to a piece of drill steel and lowered down the hollow stem of the auger to rest on the soil at the bottom of the hole. A 140 lb. weight (hammer) is repeatedly dropped 30"' to impact the top of the drill steel protruding from the top of the auger, forcing soil into the sleeve. The driller records the number of blows required to push the sampling sleeve through each of the three six inch segments of the 18 inch long sample. The sleeve and drill steel are then removed. The plug can be be replaced and additional sections of auger can be added to continue boring to collect deeper samples.

From the number of blows recorded, the engineer can estimate the strength of the soil. Laboratory tests are performed to classify the soils in the collected samples and indicate how they will behave as a construction material and how they will react to water.

Technospeak?


http://www.youtube.com/watch?v=K9igK83de9g