Cone tipped cylindrical probe for use in groundwater testing

• US 6,236,941 B1
• Filed: 03/30/1998
• Issued: 05/22/2001
• Est. Priority Date: 03/30/1998
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Massey, Auldin James, Kram, Mark L.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): WILSON, KATINA M
• Application Number:
  US09/054,290
• Time in Patent Office: 1,149 Days
• Field of Search: 73/8.A, 73/84, 702/12, 702/13, 702/2
• US Class Current: 702/12
• CPC Class Codes: G01N 33/24 Earth materials G01N33/42 takes precedence

Abstract

A piezocone for measuring the soil'"'"'s resistance to penetration and pore water pressure while being advanced into the ground by a twenty ton hydraulic cone penetrometer rig. The low pressure piezocone includes a friction sleeve and a conical tip attached to the lower end of friction sleeve. The conical tip develops the cone resistance. 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 in the cylindrical friction sleeve of the piezocone. The measurements including pore water pressure, cone resistance 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.

Claims

1. An in soil testing system for measuring soil parameters while being forcibly penetrated into the soil comprising:

a probe having a plurality of sensing means for measuring said soil parameters, said soil parameters including forces resisting tip penetration by said probe, lateral forces resisting penetration by said probe and pore water pressure in the soil measured at a plurality of depths of penetration of said probe, said probe generating electrical signals representative of said soil parameters;

means coupled to said probe for forcibly penetrating said probe into the soil;

data processing means coupled to said probe to receive said electrical signals from said probe, said data processing means processing said electrical signals to provide a designation of a soil type for the soil a pressure dissipation curve for said pore water pressure in the soil at each of said plurality of depths of penetration of said probe and a time T₅₀ required for a fifty percent pressure dissipation of said pressure dissipation curve at each of said plurality of depths of penetration of said probe;

said data processing means calculating a hydraulic conductivity for each of plurality of depths of penetration of said probe using the formula;

$k=\frac{r^2}{279.12\times <br><br>t_{50}\times <br><br>\mathrm{\alpha <br><br>}\times <br><br>q_c}$

 

where r is a radius for said probe stored in said data processing means, α

is an empirical average coefficient for said soil type, and q_c is an end bearing component of the forces resisting tip penetration by said probe; and

display means coupled to said data processing means for displaying a penetrometer dissipation analysis window which includes the hydraulic conductivity calculated by said digital processing means for each of said plurality of depths of penetration of said probe; and

said data processing means containing a Piezocone Dissipation Analysis computer software program, said Piezocone Dissipation Analysis computer software Program generating a hydrostatic pressure profile which illustrates a final pressure point for the dissipation curve of each of said plurality of depths of penetration of said probe, said Piezocone Dissipation Analysis computer software program providing a best fit line for only completed dissipation curves for each of said plurality of depths of penetration of said probe, said display means displaying said hydrostatic pressure profile and said best fit line.

2. The in soil testing system of claim 1 wherein said data processing means comprises a digital computer.

3. The in soil testing system of claim 1 wherein said means for forcibly said probe into the soil comprises:

a three axil truck having a plurality of hydraulic rams mounted inside a rear compartment of said three axil truck; and

a string of steel pipes having one end extending vertically downward from an underside of said three axile truck into the soil, said probe being attached to the opposite end of said string of steel pipes, said string of steel pipes being pushed into the soil at a constant penetration rate of two centimeters per second.

4. The in soil testing system of claim 1 wherein said display means comprises a monitor.

5. The in soil testing system of claim 1 wherein said plurality of sensing comprises:

first and second strain gauge load cells mounted within said probe, said first strain gauge load cell measuring said forces resisting tip penetration by said probe, said second strain gauge load cell measuring said lateral forces resisting penetration by said probe; and

pressure sensing means for measuring said pore water pressure in the soil at said plurality of depths of penetration, said pressure sensing means comprising a porous filter mounted in a conical tip of said probe and a pressure transducer coupled to said porous filter.

6. The in soil testing system of claim 1 further comprising a printer connected to said data processing means, said printer providing a printout of the hydraulic conductivity for each of plurality of depths of penetration of said probe.

7. The in soil testing system of claim 1 wherein said Piezocone Dissipation Analysis computer software program generates a hydraulic conductivity profile which illustrates the hydraulic conductivity for each of said plurality of depths of penetration of said probe, said display means displaying said hydraulic conductivity profile.

8. An in soil testing system for measuring soil parameters while being forcibly penetrated into the soil comprising:

a probe having a plurality of sensors for measuring said soil parameters;

said plurality of sensors including;

first and second strain gauge load cells mounted within said probe, said first strain gauge load cell measuring forces resisting tip penetration by said probe, said second strain gauge load cell measuring lateral forces resisting penetration by said probe; and

a pressure sensing device for measuring said pore water pressure in the soil at said plurality of depths of penetration;

said plurality of sensors of said probe generating electrical signals representative of said soil parameters;

means coupled to said probe for forcibly penetrating said probe into the soil;

a digital computer coupled to said plurality of sensors to receive said electrical signals from said plurality of sensors, said digital computers processing said electrical signals to provide a designation of a soil type for the soil, a pressure dissipation curve for said pore water pressure in the soil at each of said plurality of depths of penetration of said probe and a time T₅₀ required for a fifty percent pressure dissipation of said pressure dissipation curve at each of said plurality of depths of penetration of said probe;

said digital computer calculating a hydraulic conductivity for each of said plurality of depths of penetration of said probe using the formula;

$k=\frac{r^2}{279.12\times <br><br>t_{50}\times <br><br>\mathrm{\alpha <br><br>}\times <br><br>q_c}$

 

where r is a radius for said probe stored in said digital computer, α

is an empirical average coefficient for said soil type, and q_c is an end bearing component of the forces resisting tip penetration by said probe;

said digital computer calculating a water depth below surface for each of said plurality of depths of penetration of said probe using the formula;

$\begin{array}{cc}\mathrm{WDBS}=\mathrm{MD}-\frac{p_p\times <br><br>144}{d_w}& \left(5\right)\end{array}$

 

where MD is a measured depth for said probe, p_p is a final pressure for said pressure dissipation curve and d_w is a density for fresh water which is approximately 62.4 pounds per cubic foot; and

a monitor coupled to said digital computer for displaying a penetrometer dissipation analysis window which includes the hydraulic conductivity and the water depth below surface calculated by said digital computer for each of said plurality of depths of penetration of said probe.

9. The in soil testing system of claim 8 wherein said pressure device comprises a porous filter mounted in a conical tip of said probe and a pressure transducer coupled to said porous filter.

10. The in soil testing system of claim 8 wherein said means for forcibly said probe into the soil comprises:

a three axil truck having a plurality of hydraulic rams mounted inside a rear compartment of said three axil truck; and

a string of steel pipes having one end extending vertically downward from an underside of said three axile truck into the soil, said probe being attached to the opposite end of said string of steel pipes, said string of steel pipes being pushed into the soil at a constant penetration rate of two centimeters per second.

11. The in soil testing system of claim 8 further comprising a printer connected to said digital computer, said printer providing a printout of the water depth below surface and the hydraulic conductivity for each of said plurality of depths of penetration of said probe.

12. The in soil testing system of claim 8 wherein said digital computer contains a Piezocone Dissipation Analysis computer software program, said Piezocone Dissipation Analysis computer software program generating a hydrostatic pressure profile which illustrates a final pressure point for the dissipation curve of each of said plurality of depths of penetration of said probe, said Piezocone Dissipation Analysis computer software program providing a best fit line for only completed dissipation curves for each of said plurality of depths of penetration of said probe, said monitor displaying said hydrostatic pressure profile and said best fit line.

13. The in soil testing system of claim 12 wherein said Piezocone Dissipation Analysis computer software program generates a hydraulic conductivity profile which illustrates the hydraulic conductivity for each of said plurality of depths of penetration of said probe, said monitor displaying said hydraulic conductivity profile.

14. An in soil testing system for measuring soil parameters while being forcibly penetrated into the soil comprising:

a probe having a plurality of sensors for measuring said soil parameters;

said plurality of sensors including;

first and second strain gauge load cells mounted within said probe, said first strain gauge load cell measuring forces resisting tip penetration by said probe, said second strain gauge load cell measuring lateral forces resisting penetration by said probe; and

a pressure sensing device for measuring said pore water pressure in the soil at said plurality of depths of penetration, said pressure sensing device including a porous filter mounted in a conical tip of said probe and a pressure transducer mounted within said probe, said pressure transducer being connected to said porous filter;

said plurality of sensors of said probe generating electrical signals representative of said soil parameters;

means coupled to said probe for forcibly penetrating said probe into the soil;

a digital computer coupled to said plurality of sensors to receive said electrical signals from said plurality of sensors, said digital computers processing said electrical signals to provide a designation of a soil type for the soil, a pressure dissipation curve for said pore water pressure in the soil at each of said plurality of depths of penetration of said probe and a time T₅₀ required for a fifty percent pressure dissipation of said pressure dissipation curve at each of said plurality of depths of penetration of said probe;

said digital computer calculating a hydraulic conductivity for each of said plurality of depths of penetration of said $k=\frac{r^2}{279.12\times <br><br>t_{50}\times <br><br>\mathrm{\alpha <br><br>}\times <br><br>q_c}$

probe using the formula;

where r is a radius for said probe stored in said digital computer, α

is an empirical average coefficient for said soil type, and q_c is an end bearing component of the forces resisting tip penetration by said probe;

said digital computer calculating a water depth below surface for each of said plurality of depths of penetration of said probe using the formula;

$\begin{array}{cc}\mathrm{WDBS}=\mathrm{MD}-\frac{p_p\times <br><br>144}{d_w}& \left(5\right)\end{array}$

 

where MD is a measured depth for said probe, p_p is a final pressure for said pressure dissipation curve and d_w is a density for fresh water which is approximately 62.4 pounds per cubic foot;

said digital computer generating a hydrostatic pressure profile which illustrates a final pressure point for the dissipation curve of each of said plurality of depths of penetration of said probe;

said digital computer providing a best fit line for only completed dissipation curves for each of said plurality of depths of penetration of said probe;

a monitor coupled to said digital computer for displaying a penetrometer dissipation analysis window which includes the hydraulic conductivity and the water depth below surface calculated by said digital computer for each of said plurality of depths of penetration of said probe, said monitor displaying said hydrostatic pressure profile and said best fit line.

15. The in soil testing system of claim 14 wherein said means for forcibly said probe into the soil comprises:

a three axil truck having a plurality of hydraulic rams mounted inside a rear compartment of said three axil truck; and

a string of steel pipes having one end extending vertically downward from an underside of said three axile truck into the soil, said probe being attached to the opposite end of said string of steel pipes, said string of steel pipes being pushed into the soil at a constant penetration rate of two centimeters per second.

16. The in soil testing system of claim 15, wherein said string of steel pipes comprises a plurality of steel pipes, each of said plurality of steel pipes having a length of approximately one meter.

17. The in soil testing system of claim 14 further comprising a printer connected to said digital computer, said printer providing a printout of the water depth below surface and the hydraulic conductivity for each of said plurality of depths of penetration of said probe.

18. The in soil testing system of claim 14 wherein said digital computer contains a Piezocone Dissipation Analysis computer software program, said Piezocone Dissipation Analysis computer software program calculating said hydraulic conductivity and said water depth below surface for each of said plurality of depths of penetration of said probe, said Piezocone Dissipation Analysis computer software program generating said hydrostatic pressure profile and said best fit line.

19. The in soil testing system of claim 14 wherein said Piezocone Dissipation Analysis computer software program generates a hydraulic conductivity profile which illustrates the hydraulic conductivity for each of said plurality of depths of penetration of said probe, said monitor displaying said hydraulic conductivity profile.