Geotechnical Engineering ch5

Minimum requirements in a geotechnical report often include the following two recommendations:

• The overexcavation of all existing soils

• .The scarification of all existing surfaces prior to placing any fill

• .Removal of all undocumented fill

• The placement of fill in lifts no thicker than 12 in.

Expansive soils are often compacted at lower densities and higher moisture.

• .True

• False

Pumping or deflection of clayey soils is acceptable in roadway subgrade.

• True

• .False

The backscatter method of testing with a nuclear gauge should not be used when testing a thin layer of aggregate base.

• True

• .False

Which two conditions are not desirable across a footing bottom?

• Dense native soil

• Compacted fill contacting bedrock

• CL/CH soil at or under optimum

• Bedrock

A caisson was drilled to a depth of 20 ft, and upon completion water had seeped in and filled up 5 ft of the hole; what is not the proper action to take prior to pouring concrete?

• Remeasure the hole, and then redrill it to remove slough/sediment if necessary.

• Confirm that the contractor will place a tremie to the bottom of the caisson during the pour.

• .Pour low-slump concrete from the top of the caisson, making sure to vibrate from the bottom of the hole during the pour.

• Calculate the amount of concrete necessary to fill the caisson, with no adjustment made for the 5 ft. of water.

When constructing a rockery wall, the long dimension of the rocks should be perpendicular to the wall face.

• .True

• False