It consists of tool-steel driving shoe at the bottom, a steel tube (that is split longitudinally in to halves) in the middle, and a coupling at the top. The steel tube in the middle has inside and out side diameters of 34.9mm and 50.8mm, respectively.
When the bore hole is advanced to a desired depth, the drilling tools are removed. The split-spoon sampler is attached to the drilling rod and then lowered to the bottom of the bore hole. The sampler is driven in to the soil at the bottom of the bore hole by means of hammer blows. The hammer blows occur at the top of the drilling rod. The hammer weights 623N. For each blow, the hammer drops a distance of 0.762m. The number of blows required for driving the sampler through three 152.4mm interval is recorded. The sum of the number of blows required for driving the last two 152.4mm intervals is referred to as the standard penetration number; N. it is also commonly called the blow count. After driving is completed, the sampler is with drawn and the shoe and coupling are removed. The soil sample collected inside the split tube is then removed and transferred to the laboratory in small glass jars. Determination of the standard penetration number and collection of split-spoon samples are usually done at 1.5m.
|
