Besides Testing is a division of field testing corresponding to cases where ground testing is performed by ground-inserted or ground-mounted equipment. In-situ tests are typically associated with tests for which a borehole is either unnecessary or only an incidental part of the overall testing process, only needed to allow the test equipment or equipment to be inserted. The role of specialized in-situ testing for site characterization and research and development of in-situ techniques has received considerable attention over the past 15 years. The use of specialized in-situ testing is rapidly gaining increasing popularity in geotechnical engineering practice. In Europe, specialized in-situ testing has been commonly used for over 25 years. Improvements in equipment, equipment, and deployment techniques, data acquisition and analysis processes have been significant. The rapid increase in the number, variety and capacity of in-situ tests has made it difficult for practicing engineers to fully understand specialized in-situ testing as well as their benefits and limitations.
- Tests are performed in a natural environment without sample disturbances, which can cause stress, strain, harmful effects to drainage, fabric and particle arrangement, and modification.
- Continuous profiles of stratigraphy and engineering properties/features can be obtained.
- Detection of planes of weakness and defects is more probable and practical
- Methods are usually fast, repeatable, generate large amounts of information and are cost-effective
- Tests can be performed in soils that are either impossible or difficult to sample without the use of expensive specialized methods.
- A larger amount of soil can be tested for laboratory testing than is normally practicable. It may be more representative of soil mass.
- samples are not received; The tested soil cannot be identified as positive. The exception to this is the SPT in which a sample, however perturbed, is obtained.
- The fundamental behavior of soils during testing is not well understood.
- Drainage condition not known during testing
- Coherent, rational explanation is often difficult and uncertain
- The strain path exerted during the test may not be the same as the strain path induced by the full scale engineering structure
- Most push-in devices are not suitable for a wide range of ground conditions
- There is some disturbance in the ground due to the installation or placement of the device
- There is usually no direct measurement of engineering properties. Empirical correlations are commonly applied to interpret and derive engineering properties and designs