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.
Sometimes, the process is referred to as Dutch cone test because it originated from the Netherlands. This process has been accepted all over the world despite it having been invented and developed in Europe. It is among the best methods of investigating soils. Projects that deal with ground compaction mostly apply this method. Currently, various types of mechanical and electrical cone penetrometers are available. However, the electric cone is the most common.
CPT involves the use of a conical tip that is pushed into the ground at the rate of 2 centimeters per minute. The conical tip is designed with an apex angle of 60 degrees and a diameter of 35.7 millimeters. The steel rod that connects to the pinecone has the same diameter of 35.7 millimeters as the pinecone. The rate at which the pinecone is pushed into the soil can be 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.
Friction is recorded by the use of transducers which are attached to the electric CPT. In cases where the CPT probe is integrated with pore-water pressure sensors, it is normally called a CPTU. One should ensure that the filter ring within the pore-water element is saturated with water completely. If the element is not completely saturated, it will lead to erroneous results being 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 works by measuring pinecone resistance and sleeve friction to determine the friction ratio, denoted as FR. Sleeve friction usually reflects the variation of lateral earth pressure within the ground. As such, it can be used in the investigation of the effect of ground compaction on the state of stress. Sleeve and pinecone friction measurements also get affected strongly by effective overburden pressure.
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.
Sometimes, the process is referred to as Dutch cone test because it originated from the Netherlands. This process has been accepted all over the world despite it having been invented and developed in Europe. It is among the best methods of investigating soils. Projects that deal with ground compaction mostly apply this method. Currently, various types of mechanical and electrical cone penetrometers are available. However, the electric cone is the most common.
CPT involves the use of a conical tip that is pushed into the ground at the rate of 2 centimeters per minute. The conical tip is designed with an apex angle of 60 degrees and a diameter of 35.7 millimeters. The steel rod that connects to the pinecone has the same diameter of 35.7 millimeters as the pinecone. The rate at which the pinecone is pushed into the soil can be 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.
Friction is recorded by the use of transducers which are attached to the electric CPT. In cases where the CPT probe is integrated with pore-water pressure sensors, it is normally called a CPTU. One should ensure that the filter ring within the pore-water element is saturated with water completely. If the element is not completely saturated, it will lead to erroneous results being 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 works by measuring pinecone resistance and sleeve friction to determine the friction ratio, denoted as FR. Sleeve friction usually reflects the variation of lateral earth pressure within the ground. As such, it can be used in the investigation of the effect of ground compaction on the state of stress. Sleeve and pinecone friction measurements also get affected strongly by effective overburden pressure.
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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