Dilatometers Settle In

by John H. Schmertmann, Consulting Engr.; Schmertmann & Crapps, Inc., Gainesville, FL.,

Serial Information: Civil Engineering—ASCE, 1988, Vol. 58, Issue 3, Pg. 68-70

Document Type: Feature article


The benefits of the dilatometer test DMT are described. This geotechnical in situ testing tool was developed and patented by an Italian professor and engineer named Silvano Marchetti. The DMT delivers, according to the author, a surprising combination of accuracy, reproducibility, ruggedness, economy, and versatility. Professor Marchetti combined the simplicity and economy of a penetration test with the sophistication of a test that also measures an in situ stress and modulus. The DMT is most useful for the rapid calculation of expected settlements in many types of soil, but it also has many other uses. For those unfamiliar with the DMT, the article explains how a technician operator uses a drill rig or other suitable equipment to push or drive the blade into the soil to be tested, stopping at suitably spaced test depth intervals as close as 150 mm. At each depth the operator uses gas pressure to expand and deflate a stainless steel membrane horizontally in the soil and obtains four data readings. The data is then interpreted to reveal such qualities as soil type, in situ lateral stress, the excess hydrostatic pore pressure, undrained shear strength, the friction angle and in situ pressure in sands, to name a few, all for use in any rational design procedures.

Subject Headings: Soil pressure | Soil settlement | Soil strength | Measuring instruments | Faculty | Penetration tests | Soil classification | Soil gas

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