Saving Foundation Costs - The Marchetti Dilatometer Test- 2/12/10
Saving Foundation Costs - The Marchetti Dilatometer Test
Ever feel like parts of your construction project are costing you more than they should? Does it seem like you are working on the one piece of property in town that has those terrible soils that are costing you a fortune? You're not alone. Below, please find information that, in the right circumstances, may help your cause.
Subsurface soil conditions in the Carolinas have traditionally been evaluated for design purposes by use of Standard Penetration Testing (SPT). Traditional methods of estimating allowable bearing pressures for soils in the Piedmont geological area are generally very affordable and produce results that, in many cases, are conservative but reasonable for foundations used in low to moderate rise structures. However, as growth continues through the Carolinas and "ideal" sites become less prevalent, many structures are being built on soils that are classified, for engineering purposes, as "SILT." These SILT soils produce test results that can lead to recommendations of lower allowable bearing pressures and elevated settlement potential, thus increasing foundation sizes and expenses.
A test method that is not new, but is gaining use in the geotechnical engineering field is commonly called the Marchetti Dilatometer Test (DMT) (see Figures 1). The DMT provides the following advantages:
Inexpensive method for determining important soil parameters
Simple and quick test to perform
Complies with ASTM D 6635
Test results can be used to correlate many soil properties for engineering analysis
Test provides more accurate bearing capacity allowance
Test can be performed on relatively undistrurbed soils
Test can be performed at multiple depths and locations
The test can be performed independently or as a supplement to SPT testing
Test provides more accurate soil strength and settlement analysis
The test can potentially save clients unnecessary expenses
Comparisons of test results between the DMT, traditional SPT testing and other test methods have found the DMT method to provide a more accurate depiction of the in-place condition of the subsurface materials, allowing analysis that may yield more favorable design parameters. These results can lead to increased allowable foundation bearing parameters and, thus, a potential significant savings in foundation costs to owners.
If ESP can be of assistance with these type of technical matters or in other areas of technical expertise, please contact us for discussion with an experienced professional. Our goal is to help our clients make the best use of their resources.
Next Issue's Articles:
Density and Land Development, Why is it so confusing?
and
Certified Floodplain Surveyor (CFS), How can one benefit you?
