Cone Penetration Testing

Dissipation Testing

Piezocones measure porewater pressure dynamically, which is to say, it is measured as the probe is advanced. In coarse-grained granular materials of high permeability, the measured porewater pressure will closely match the native equilibrium pressure as defined by the groundwater regime. However, in fine-grained materials of low permeability the dynamic porewater pressure will be a function of the applied stress during the shearing of the material as the probe advances which will set up a porewater pressure, well in excess of the equilibrium porewater pressure.

Stopping the probe as this point and measuring the rate over time that this pressure dissipates to the equilibrium pressure is called a dissipation test. The results of this test are a powerful field test in respect of permeability and thus consolidation properties of the soil in addition to establishing equilibrium water pressure profiles. The test is a semi-direct measurement of the horizontal coefficient of consolidation and would inform settlement and seepage analyses more directly than empirical correlations. Dissipation testing can also be undertaken using the dilatometer apparatus.

Cone Penetration Testing

Dissipation Testing

Cone Penetration Testing

Dissipation Testing

Piezocones measure porewater pressure dynamically, which is to say, it is measured as the probe is advanced. In coarse-grained granular materials of high permeability, the measured porewater pressure will closely match the native equilibrium pressure as defined by the groundwater regime. However, in fine-grained materials of low permeability the dynamic porewater pressure will be a function of the applied stress during the shearing of the material as the probe advances which will set up a porewater pressure, well in excess of the equilibrium porewater pressure. Stopping the probe as this point and measuring the rate over time that this pressure dissipates to the equilibrium pressure is called a dissipation test. The results of this test are a powerful field test in respect of permeability and thus consolidation properties of the soil in addition to establishing equilibrium water pressure profiles. The test is a semi-direct measurement of the horizontal coefficient of consolidation and would inform settlement and seepage analyses more directly than empirical correlations. Dissipation testing can also be undertaken using the dilatometer apparatus.