1. Large strain detection is a detection method that impacts the pile top with a heavy hammer, measures the velocity and force time-history curve of the pile top, and analyzes and judges the vertical compressive bearing capacity of a single pile and the integrity of the pile body through wave theory. It can be used for the detection of broken piles, which is a term for the quality detection of pile foundation in the substructure of building structures.
2. Small strain detection, also known as low strain dynamic detection, is relative to large strain dynamic detection.
Low strain testing is engaged in technical services, consulting and development related to geotechnical engineering, structural testing, engineering geophysical prospecting, engineering surveying and mapping, building quality testing, indoor environmental quality testing, environmental engineering, safety evaluation, water conservancy design and construction, water conservancy and hydropower, railways, highway transportation, chemical industry, municipal administration and other industries, geological disasters and environmental protection, as well as extended business related to the above businesses.
Extended data:
Small strain has its own limitations:
1. For piles with multiple defects, the stress wave is reflected and transmitted many times in the pile, so it is very complicated and inaccurate to judge the measured waveform, and there will be great errors in judging the second and third defects, and generally the third defect is not judged.
2. The thickness of sediment at the bottom of pile cannot be calculated quantitatively. Only the rock-socketed effect of end-bearing piles can be qualitatively judged. Because of the embedding of rocks, sometimes there will be strong negative reflection waves, which will seriously affect the judgment of reflection waves and sediments at the bottom of piles.
3. The pile quality can only be described qualitatively, but not quantitatively, and longitudinal cracks can not be identified, but transverse cracks and joints can be reflected, but the degree is difficult to grasp and it is easy to be misjudged as serious defects.
4. The relative shrinkage of pile body after gradually expanding diameter is easy to be misjudged as shrinkage. When the gradient diameter decreases or the segregation is large, the reflection waveform of the defect is not obvious.
5. The strength of pile concrete cannot be provided.
reference data
Baidu encyclopedia-small strain detection
Baidu encyclopedia-large strain detection