Cone penetrometer test is also called cone penetration test, usually abbreviated as CPT. This technique is used to gauge the geotechnical engineering qualities of soils. Also, it is used in determining the delineation of stratigraphy of soils. CPT was invented in the 1950s in Delft. The scientists that invented the process were researching soil soils at the Dutch soil mechanics laboratory. This is worth knowing about cone penetrometer test for soil.
Given the history of CPT, it is sometimes referred to as Dutch cone test. Although this method was invented and developed in Europe, it is now recognized worldwide as one of the best methods used in investigation of soils. The method is used mostly in ground compaction projects. There are several types of electric and mechanical cone penetrometers in existence today, but the most commonly used is electric cone.
CPT utilizes a conical tip that is normally pushed into the earth at a rate of 2 cm per minute. This conical tip has a diameter of 35.7 millimeter and an apex angle of 60 degrees. A steel rod connects to the conical tip and has a similar diameter as the conical tip. The pinecone is normally pushed into the earth at a rate that varies between 1.5 and 2.5 centimeters per second.
When the pinecone is being pushed deeper into the soil, there is resistance at its tip and also along its shaft. This friction is measured. Friction sleeve is the portion that is located just after the pinecone, and it is subjected to friction. In most cases, the friction sleeve is 15,000 millimeters in diameter.
The recording of the friction is done using transducers that make part of the electric CPT. If the CPT probe is incorporated with a pore-water pressure sensor, it is referred to as a CPTU. It is vital that the filter ring of the pore-water element is completely saturated with water. Failing to saturate the element with water will cause erroneous results to be recorded by the piezo-transducer.
CPTs can also be used to determine other elements of the soil by having different types of sensors incorporated. It is possible for CPTs to measure the velocity and acceleration of vibration when they have vibration sensors. Results from an SPT usually depend on the operator. This is not the case with CPT since the process is highly standardized. As such, CPTs are reproducible because the results from them are independent of the operator.
CPT functions by measuring sleeve friction and pinecone resistance in order to ascertain the friction ratio, which is normally denoted as FR. Variations in lateral earth pressure in the ground is reflected by sleeve friction. Hence, this can be used in investigating how soil compaction affects the condition on stress. Also, effective overburden pressure can be immensely affected by pinecone and sleeve friction measurements.
CPT aims to obtain information concerning ground stratification and variation in soil properties both in vertical and horizontal directions. The friction ratio is an indicator of soil type and provides useful information in the evaluation of alternative compaction methods. Measurements of excess pore water pressure are used in detecting seams and layers of fine-grained materials.
Given the history of CPT, it is sometimes referred to as Dutch cone test. Although this method was invented and developed in Europe, it is now recognized worldwide as one of the best methods used in investigation of soils. The method is used mostly in ground compaction projects. There are several types of electric and mechanical cone penetrometers in existence today, but the most commonly used is electric cone.
CPT utilizes a conical tip that is normally pushed into the earth at a rate of 2 cm per minute. This conical tip has a diameter of 35.7 millimeter and an apex angle of 60 degrees. A steel rod connects to the conical tip and has a similar diameter as the conical tip. The pinecone is normally pushed into the earth at a rate that varies between 1.5 and 2.5 centimeters per second.
When the pinecone is being pushed deeper into the soil, there is resistance at its tip and also along its shaft. This friction is measured. Friction sleeve is the portion that is located just after the pinecone, and it is subjected to friction. In most cases, the friction sleeve is 15,000 millimeters in diameter.
The recording of the friction is done using transducers that make part of the electric CPT. If the CPT probe is incorporated with a pore-water pressure sensor, it is referred to as a CPTU. It is vital that the filter ring of the pore-water element is completely saturated with water. Failing to saturate the element with water will cause erroneous results to be recorded by the piezo-transducer.
CPTs can also be used to determine other elements of the soil by having different types of sensors incorporated. It is possible for CPTs to measure the velocity and acceleration of vibration when they have vibration sensors. Results from an SPT usually depend on the operator. This is not the case with CPT since the process is highly standardized. As such, CPTs are reproducible because the results from them are independent of the operator.
CPT functions by measuring sleeve friction and pinecone resistance in order to ascertain the friction ratio, which is normally denoted as FR. Variations in lateral earth pressure in the ground is reflected by sleeve friction. Hence, this can be used in investigating how soil compaction affects the condition on stress. Also, effective overburden pressure can be immensely affected by pinecone and sleeve friction measurements.
CPT aims to obtain information concerning ground stratification and variation in soil properties both in vertical and horizontal directions. The friction ratio is an indicator of soil type and provides useful information in the evaluation of alternative compaction methods. Measurements of excess pore water pressure are used in detecting seams and layers of fine-grained materials.
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