United States of America as Represented by the Secretary of the Air Force

Hugh Steeper Limited

Roger Sidey

David Hart

Robert Basford

David Hawkins

David Knight

A system for measuring transient pore water pressure in the ground utilizes a probe member having a unique arrangement of a pressure sensor and a soil stress isolation filter. The probe member has a body portion with a hollow cavity defined therein. The pressure sensor in the form of a ceramic transducer is mounted in the cavity, and the filter in the form of a circumferential gap formed on the body communicates with the cavity. The filter is also configured for isolating the sensor from effective soil fabric stresses while allowing access to the transducer by pore water pressure. A coupling medium in the form of silicon grease fills the cavity so as to transmit the pore water pressure to the transducer.

Pressure sensor and soil stress isolation filter arrangement in a pore

A system for measuring transient pore water pressure in the ground utilizes a unique probe assembly and two-stage emplacement technique therefor. In the initial stage, a large, robust primary probe member of a probe assembly in the measuring system is pushed into the ground to the selected measurement region. In the final stage, a small secondary probe member which is contained within the primary probe member is ejected into the soil when the primary probe member is emplaced at the desired region. The secondary probe member contains a pressure sensor in the form of a highly miniaturized, fast response piezometer which is capable of achieving a responsive coupling with interstitial fluid in the region of measurement.

Pore pressure probe assembly and two-stage emplacement thereof

Prosthesis

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Richmond, United Kingdom

Roger Sidey