Measuring existing lateral earth pressure

[aeoliantexan]

We are investigating a bridge pier on the sloped bank of a lake that has deflected towards the lake. It is founded on four drilled shafts and surrounded with about 30 feet of compacted clay or sandy clay backfill with a 30-degree slope. We want to know whether it is being deflected by excessive lateral soil pressure, possibly because the slope is marginally unstable.

Can we accurately measure the lateral earth pressure using a Dilatometer in a borehole drilled near the face of the pier?

Is there a better way?

Would any one recommend using the Iowa Stepped Blade test?

 

[GeoPaveTraffic]

I'm not familure with the Iowa stepped blade test, so can't comment.

I don't think a dilatometer will work since i believe it will give you more of an average pressure around the full borehole perimeter.

If the slope is moving, then the bridge pier is not going to be able to hold it, period. The brige wasn't designed for the kind of force that moving slope exerts.

My suggestion is to first determine if the slope is moving (I've never seen a marginally unstable slope). If the slope is moving, figure out how to stabilize the slope. Then figure out how to repair the bridge.

Mike Lambert

 

[Hanks864]

You could monitor slope movement with the instalation of slope indicator inclinometers. And also perform a couple of boreholes and then do some triaxial tests to investigate the shear strength properties right now, compare these properties to the ones reported before the construction of the project, look for changes in moisture content, SPT blow counts, and C and Phi parameters. Then perform a stability analysis to verify that your geometry is not unstable.