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.
The process of CPT involves the use of a pinecone-tipped shaft. The conical tip is pushed into the ground at a rate of 2 centimeters per second. The tip has a diameter of 35.7 millimeters and an angle of 60 degrees at the apex. A rod of the same diameter as the pinecone is connected to the pinecone. As said earlier, the pinecone is pushed into the soil at a rate of 2 centimeters per minute. However, the speed is generally varied between 1.5 and 2.5 centimeters per second.
As the pinecone continues to be pushed into the soil, the penetration resistance at the tip and along the shaft is measured. The section of the shaft that experiences friction is referred to as the friction sleeve and it is located exactly after the pinecone. The surface area of the friction sleeve is usually 15, 000 square millimeters.
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.
One can include other types of sensors in the CPT in order to measure other elements of the ground that is being worked on. For example, one can include vibration sensors that will help determine acceleration and vibration velocity. CPT is a standardized operation whose results are not dependent on the operator like is the case with SPT. Since CPT results are independent of the operator, it implies that they are reproducible.
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.
The purpose of CPT is to understand in detail soil variation and stratification characteristics both vertically and horizontally. The type of soil is indicated by the friction ratio. Alternative methods of compaction can be selected based on the FR because it indicates the soil type. Layers and seams that contain fine grained-materials are determined by measuring the excess pore-water pressure.
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.
The process of CPT involves the use of a pinecone-tipped shaft. The conical tip is pushed into the ground at a rate of 2 centimeters per second. The tip has a diameter of 35.7 millimeters and an angle of 60 degrees at the apex. A rod of the same diameter as the pinecone is connected to the pinecone. As said earlier, the pinecone is pushed into the soil at a rate of 2 centimeters per minute. However, the speed is generally varied between 1.5 and 2.5 centimeters per second.
As the pinecone continues to be pushed into the soil, the penetration resistance at the tip and along the shaft is measured. The section of the shaft that experiences friction is referred to as the friction sleeve and it is located exactly after the pinecone. The surface area of the friction sleeve is usually 15, 000 square millimeters.
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.
One can include other types of sensors in the CPT in order to measure other elements of the ground that is being worked on. For example, one can include vibration sensors that will help determine acceleration and vibration velocity. CPT is a standardized operation whose results are not dependent on the operator like is the case with SPT. Since CPT results are independent of the operator, it implies that they are reproducible.
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.
The purpose of CPT is to understand in detail soil variation and stratification characteristics both vertically and horizontally. The type of soil is indicated by the friction ratio. Alternative methods of compaction can be selected based on the FR because it indicates the soil type. Layers and seams that contain fine grained-materials are determined by measuring the excess pore-water pressure.
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