Pressuremeter Test

Pressuremeter Test. High Pressure Dilatometer (HPD) Borehole test suitable for rock and higher strength fine soils Operated in conjunction with a rotary drilling rig that is used to drill the test pocket lower the probe into the.

Inserting The PressuremeterConstruction and CalibrationAdvantages and Limitations of The Pressuremeter TestThe interpretation of the pressuremeter test must take account of the disturbance caused by the method used to place the probe in the ground The least disruptive of the methods is self boring where disturbance is often small enough to lie within the elastic range of the material and is therefore recoverable This is the only technique with the potential to determine directly the insitu lateral stress $\\sigma_{ho}$ the major source of uncertainty when calculating the coefficient of earth pressure at rest $k_o$ However all methods allow the confining stress to be inferred The disturbance caused by preboring and pushing is never recoverable However for any pressuremeter test it is possible to erase the stress history of the loaded material by taking it to a significantly higher stress than it has previously seen and then to reverse the direction of loading The point of reversal is a new origin and the stressstrain response will be that due to the undisturbed properties of th There are many designs of pressuremeter in current use some of which are of complex construction Figure 5 on the right (click for fullsize) is a view of the inside of a 6 arm Cambridge self boring pressuremeter There are transducers for measuring the radial displacement of the membrane at 6 places and the total and effective pressure being applied to the cavity wall The electronics for the signal conditioning including the conversion from analogue to digital is contained in the probe itself Apart from supplying power the output of the probe may be connected directly to the serial port of a small computer This approach is necessary in order to obtain a high resolution free of noise Pressuremeters with local instrumentation are able to resolve without difficulty displacements of 05 microns and pressure changes of 01kPa Pressuremeters can be expanded using air or a nonconducting fluid such as light transformer oil There are automated systems for pressurising the equipment Advantages 1 A large number of fundamental soil properties are obtained from a single test 2 To derive these properties no empirical correcting factors whatever are needed 3 Measurements are made insituat the appropriate confining stress 4 A large volume of material is tested a typical test loads a column of material 05 metres high and extending to more than 10 times the expanded cavity radius This is the equivalent of at least 1000 triaxial tests on 38mm samples 5 Representative loads are Limitations 1 The instrument will not penetrate gravels claystones or the like so generally pressuremeter testing requires support from conventional drilling techniques 2 Failure planes and deformation modes are not always appropriate to those occurring in the final design An estimate of the anisotropy of the material will be required in order to derive vertical parameters from lateral values 3 Many familiar design rules and empirical factors are based on parameters obtained from traditional tech.

Pressuremeter Testing Insitu Site Investigation

T he pressuremeter test is an insitu testing method used to achieve a quick measure of the insitu stressstrain relationship of the soil In principle the pressuremeter test is performed by applying pressure to the sidewalls of a borehole and observing the corresponding deformation The pressuremeter consists of two parts the readout unit which rests on the ground surface and the probe that is inserted into the borehole (ground).

An introduction to pressuremeters Cambridge Insitu Limited

The pressuremeter test is an insitu testing method used to determine the stressstrain response of the tested soil The pressuremeter test also known as the “Ménard Pressuremeter” (MPM) test is performed by applying pressure to the sidewalls of a borehole and recording the corresponding deformation The test procedure involves drilling a borehole and placing a pressuremeter probe to the required depth.