Pressure Meter TEST
The PMT is typically performed by inserting a cylindrical probe into an open borehole, supporting it at the test depth, and then inflating a flexible membrane in the lateral direction to a radial strain of as much as 40% depending on the probe design. The PMT operator may expand the pressuremeter probe in equal pressure increments (stress controlled test) or in equal volume increments , typically stopping the test when initial volume of the probe has doubled or when reaching the maximum allowable pressure. About 40 data points are obtained from a strain controlled test versus and about 10 data points from a stress controlled test, thus a better defined curve can be obtained from strain controlled tests. Creep tests can be performed near the yield point of the test to evaluate time effects of the modulus (Figure 3). Ideally the PMT provides an axisymmetric, plane strain test (the horizontal plane), typically drained in sands and silts, and undrained in cohesive soils. Early PMT probes employed guard cells at their top and bottom to force the measurement cell located between them to expand only in the lateral direction. Briaud (1992) showed that the error in test results did not exceed 5% for single-cell probes (Texam in Figure 1) with a length at least six times its diameter. Researchers have also used self‑boring and push-in probes with some success in specific types of soils. Probes may also be designed with very stiff membranes for testing at high pressures and lower strain in soft rock.
land surveying is the technique, profession, and science of determining the terrestrial or three-dimensional position of points and the distances and angles between them. A land surveying professional is called a land surveyor. These points are usually on the surface of the Earth, and they are often used to establish land maps and boundaries for ownership, locations like building corners or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales.
Surveying has been an element in the development of the human environment since the beginning of recorded history. The planning and execution of most forms of construction require it. It is also used in transport, communications, mapping, and the definition of legal boundaries for land ownership. It is an important tool for research in many other scientific disciplines.