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 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.
The penetration resistance at the tip and along the shaft of the pinecone is measured as the pinecone is pushed deeper into the ground. Friction is experienced where the shaft connects to the pinecone. This area is known as the friction sleeve. Normally, the friction sleeve has a surface area of 15,000 square millimeters.
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.
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.
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 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.
The penetration resistance at the tip and along the shaft of the pinecone is measured as the pinecone is pushed deeper into the ground. Friction is experienced where the shaft connects to the pinecone. This area is known as the friction sleeve. Normally, the friction sleeve has a surface area of 15,000 square millimeters.
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.
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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