Method and system for measuring pore-fluid pressure

Abstract

A method for measuring pore pressure is provided using a rigid piezometer that does not need a filter and can be used to measure pore-water pressures in partially frozen soils. This method also can be used to measure pore pressure in a porous media when the hydraulic conductivity of the porous media is low or there is limited amount of pore-fluid available to transfer the pressures. A piezometer is also provided, including: a tube for hydraulic fluid; first and second valves to control fluid flow in the tube and into a porous medium; and a fitting wherein a pressure sensor is positioned to measure fluid pressure in the hydraulic fluid in the tube and a hydraulic fluid droplet ejected from an end of the tube into the porous medium; and an interface of the hydraulic fluid with the pore-fluid within the porous medium, using the droplet placed into the porous medium. The tube (or part of the tube), valves, fittings, and pressure sensor may be enclosed in a housing.

What is claimed is: 
     
         1 . A piezometer, comprising:
 a housing;   means to place piezometer fluid into a porous medium; and   means for determining the pore pressure as the pore pressure is transferred to the piezometer fluid.   
     
     
         2 . The piezometer of  claim 1  wherein a filter is not used. 
     
     
         3 . The piezometer of  claim 1  wherein the piezometer fluid does not freeze at a freezing temperature of a pore-fluid within the porous medium. 
     
     
         4 . The piezometer of  claim 1  wherein the piezometer fluid can sustain negative pressures less than cavitation pressure of water, without cavitation and without preconditioning the piezometer fluid by extreme pressures to sustain negative pressures. 
     
     
         5 . A method of measuring pore pressure comprising:
 placing piezometer fluid into a porous medium; and   providing an interface between the piezometer fluid and a pore-fluid, the interface within the porous medium; wherein the pore pressure is measured wherein the piezometer fluid caps an entrance of a piezometer thereby preventing free gas from entering the piezometer.