Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
1998-03-30
2001-05-22
Williams, Hezron (Department: 2856)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
C702S012000, C702S002000, C073S084000, C073S038000
Reexamination Certificate
active
06236941
ABSTRACT:
A computer program listing related to this invention is included in a microfiche appendix on one microfiche having a total of 88 frames pursuant to 37 CFR 1.96(b).
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an apparatus for ground water testing. More specifically, the present invention relates to a cone tipped cylindrical probe or piezocone which is used as an effective means of pore pressure measurements which can be converted into values for water table evaluation for accessing environmental site conditions.
2. Description of the Prior Art
The cone penetration test was originally developed to measure in-situ soil properties for the design of deep foundations. The electric version of the cone penetration test was introduced commercially in the nineteen seventies primarily as a geotechnical exploration tool. More recently, the cone penetration test range of applications has been extended to environmental site investigations.
The electric cone penetration test is currently being used as an effective means of hydrogeologic site characterization and subsurface plume tracking. An electric cone penetration test probe or piezocone measures pore water pressure and soil resistance to penetration while being advanced into the ground by an approximately 20-ton hydraulic cone penetrometer rig.
Computer processing of the piezocone measurements generally provides detailed stratigraphic profiles which depict depths of water bearing formations and variations in permeability. This data may then be used to determine the optimum depths at which to conduct ground water sampling for plume delineation; to determine direction and gradient of subsurface water flow; to check for aquifer communication and for monitoring of remediation efforts.
The piezocone has several advantages over conventional cone penetration testing methods and apparatus including: (1) the ability to distinguish between drained, partially drained and undrained soils; (2) the ability to correct measured cone data to account for unbalanced water forces due to unequal end areas in cone design; (3) the ability to evaluate flow and consolidation characteristics; (4) the ability to assess equilibrium groundwater conditions; (5) improved soil profiling and identification; and (6) improved evaluation of geotechnical parameters.
While there are a number of commercially available piezocones which may be used for hydrogeologic site characterization and subsurface plume tracking there is a need for a piezocone which will provide very accurate pore pressure measurements. In particular, the piezocone should be able to provide precise values of pore pressure having a total error of less than 0.9 inches of water.
SUMMARY OF THE INVENTION
The present invention overcomes some of the disadvantages of the prior art including those mentioned above in that it comprises a relatively simple yet highly effective electric cone penetration test probe for providing precise values of pore pressure which may then be used for hydrogeologic site characterization.
The electric cone penetration test unit probe of the present invention or piezocone measures the soil's resistance to penetration and pore water pressure while being advanced into the ground be a twenty ton hydraulic cone penetrometer rig.
During a push operation utilizing piezocones, a high pressure piezocone of about 250 psi full scale output or higher is generally used for the first push since zones in the ground are typically aquitards. This first push allows the user of the high pressure piezocone to identify course grained zone/material and fine grained zone/material in the ground. During a second push, a low pressure, high pressure piezocone with approximately a 25 psi full scale output is used to evaluate water levels by measuring pressures in course grained materials. Measurement of pore pressures in coarse grained materials typically takes less time than fine grain materials since equilibrium is established rapidly during dissipation in coarse grained materials.
The low pressure piezocone includes a friction sleeve and a conical tip attached to the lower end of friction sleeve. The conical tip has an end bearing component of penetration developed thereon. Cone resistance q., which is the end bearing component of penetration resistance, is measured by a load cell within the piezocone. The friction sleeve is an isolated cylindrical sleeve which measures the resistance of the soil as the sleeve passes through the soil. The pore water pressure is measured by a porous element mounted in the conical tip of the piezocone and a pressure transducer mounted within the piezocone behind the conical tip.
The low pressure piezocone measurements including pore water pressure, cone resistance q
c
and the soil resistance are supplied to a computer which includes a Piezocone Dissipation Analysis program for processing the piezocone measurements to generate dissipation curves for each depth at which the piezocone provides hydrogeologic site characterization data. Soil classification is also provided from a data file stored within the computer.
The computer uses the Piezocone Dissipation Analysis program to generate a Hydrostatic Pressure Profile curve and a Hydraulic Conductivity Profile Plot. The computer also uses the Piezocone Dissipation Analysis program to provide a water depth below surface estimate which occurs at the Hydrostatic Pressure Profile curve zero pressure intercept.
REFERENCES:
patent: 4442701 (1984-04-01), Cowherd et al.
patent: 4806153 (1989-02-01), Sakai et al.
patent: 4969111 (1990-11-01), Merva
patent: 5042595 (1991-08-01), Ladanyi
patent: 5109702 (1992-05-01), Charlie et al.
patent: 5316950 (1994-05-01), Apitz
patent: 5377551 (1995-01-01), Vacquer
patent: 5616833 (1997-04-01), Anderson
Kram Mark L.
Massey Auldin James
Kalmbaugh David
The United States of America as represented by the Secretary of
Williams Hezron
Wilson Katina
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