NOTES on the STANDARD PENETRATION TEST（标准贯入度试验）.pdf

GE 441 Advanced Engineering Geology Geotechnics Spring 2004 NOTES on the STANDARD PENETRATION TEST Origins of the Standard Penetration Test Around 1902 Colonel Charles R. Gow, owner of the Gow Construction Co. in Boston, began making exploratory borings using 1-inch diameter drive samplers (Fig. 1). Up until that time, contractors used wash borings with cuttings, similar to the methods presently used in advancing water wells. During the late 1920s and early 1930s, the procedure was standardized by Harry Mohr, one of Gow’s engineers, then with Raymond Concrete Pile Co. (H.A. Mohr, 1940, Exploration of Soil Conditions and Sampling Operations: Bull 269, Graduate School of Eng’g, Harvard University). Mohr developed a slightly larger diameter split- spoon drive sampler and recorded the number of blow counts per foot of penetration on an 18-inch deep sample round, using a 140-lb hammer dropping 30 inches, pushing a 2-inch outside diameter sampler, while recovering a 1-3/8 inch diameter sample, as shown in Figs. 2 and 3. The value recorded for the first round of advance is usually discarded because of fall-in and contamination in the borehole. The second pair of numbers are then combined and reported as a single value for the last 12 inches (1 foot). This value is reported as the SPT blowcount value, commonly termed “N”. Not everyone used Gow’s sampler, which originated in the Boston area, but Karl Terzaghi liked it. Terzaghi and Arthur Casagrande vigorously sponsored adoption of the split spoon sampling procedure through the auspices of ASCE’s Committee on Sampling and Testing of the Soil Mechanics and Foundations Division of ASCE, forme