The term cone penetration test (CPT) can also be used to refer to cone penetrometer test. Geotechnical engineering properties of soils and the delineation of stratigraphy of the soil are determined by carrying out this test. CPT was invented in Delft in the 1950s by scientists who were investigating soft soils. This took place in the Dutch Laboratory for earth mechanics. This is what cone penetrometer test for soil entails.
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.
An electric CPT has a transducer which is used to measure and record the friction. The name CPTU is used to refer to a CPT probe that has a pore-water pressure sensor. In CPTU, the filter ring of the pore-water component has to be saturated with water completely when it is being used. Otherwise, the piezo-transducer will take erroneous recordings.
It is possible to include other kinds of sensors in the CPT so that it can measure other aspects of the ground being worked on. For instance, vibration sensors can be included to help in determining vibration velocity and acceleration. CPT is a very standardized test, with results not being operator-dependent like it is with SPT. The fact that the results are not operator dependent makes them reproducible.
Sleeve friction and pinecone resistance which are measured by CPT are used to gauge the friction ratio (FR). Difference in lateral earth pressure in the ground is indicated by the sleeve friction. Therefore, the state of stress in relation to ground compaction can be determined using the sleeve friction. Overburdened pressure interferes with the measurement of sleeve and pinecone friction to a greater extent.
The purpose of CPT is to gather information about soil variation and stratification in both horizontal and vertical directions. Friction ratio is used in identifying the type of soil and is used in providing information on alternative compaction techniques. On the other hand, measuring excess pore-water pressure is used in ascertaining layers and seams in 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.
An electric CPT has a transducer which is used to measure and record the friction. The name CPTU is used to refer to a CPT probe that has a pore-water pressure sensor. In CPTU, the filter ring of the pore-water component has to be saturated with water completely when it is being used. Otherwise, the piezo-transducer will take erroneous recordings.
It is possible to include other kinds of sensors in the CPT so that it can measure other aspects of the ground being worked on. For instance, vibration sensors can be included to help in determining vibration velocity and acceleration. CPT is a very standardized test, with results not being operator-dependent like it is with SPT. The fact that the results are not operator dependent makes them reproducible.
Sleeve friction and pinecone resistance which are measured by CPT are used to gauge the friction ratio (FR). Difference in lateral earth pressure in the ground is indicated by the sleeve friction. Therefore, the state of stress in relation to ground compaction can be determined using the sleeve friction. Overburdened pressure interferes with the measurement of sleeve and pinecone friction to a greater extent.
The purpose of CPT is to gather information about soil variation and stratification in both horizontal and vertical directions. Friction ratio is used in identifying the type of soil and is used in providing information on alternative compaction techniques. On the other hand, measuring excess pore-water pressure is used in ascertaining layers and seams in fine-grained materials.
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