Cone penetrometer test is also referred to as cone penetration test, often abbreviated as CPT. This is a method that is used in the determination of geotechnical engineering properties of soils and the delineation of soil stratigraphy. The invention of CPT happened in the 1950s in Delft. The invention happened in the Dutch Lab for Soil Mechanics when scientists were investigating soft soils. Here are facts regarding cone penetrometer test for soil.
This test is at times called Dutch cone test due to its origin. Despite being invented and developed in Europe, CPT is now a recognized technique that is used widely in the world to investigate soils. This technique is in most cases used in ground compaction activities. The market has a number of mechanical and electric CPTs, but the widely used method is the 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.
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.
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.
This test is at times called Dutch cone test due to its origin. Despite being invented and developed in Europe, CPT is now a recognized technique that is used widely in the world to investigate soils. This technique is in most cases used in ground compaction activities. The market has a number of mechanical and electric CPTs, but the widely used method is the 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.
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.
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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