Soil sample liner assembly having permanently attached core catcher for use in dual tube sampling system

Abstract

A soil sample liner assembly having a permanently attached core catcher is disclosed for use in a dual tube sampling system. The liner assembly includes a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending between the ends. A core catcher is positioned within the tube and permanently attached at its lower end. The core catcher includes a plurality of resilient fingers that deflect outwardly to allow soil to pass into the tube and prevent soil from falling back out. The liner assembly has its lower end supported by an inner ledge of a cutting shoe of the dual tube sampling system. The liner assembly with the permanently attached core catcher is removable through the upper end of the outer casing without disturbing the attachment between the cutting shoe and the outer casing while the sampling system remains in the ground.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to devices for obtaining soil samples from below the surface of the ground. In particular, the present invention relates to soil sample liners for use in dual tube soil sampling systems.

[0003] 2. Description of the Related Art

[0004] Soil sampling systems are commonly used to obtain soil samples from below the surface of the ground. The soil samples are used to determine soil conditions prior to construction, to locate mineral deposits, to study chemical dissipation and residue, to determine the concentration of environmental contaminants, to investigate hazardous waste sites, and in other ways well known in the art.

[0005] A variety of soil sampling systems are known in the art. For example, one method of continuous soil sampling involves repeatedly driving and retrieving a soil probe sampler in-and-out of the same probe hole. A first sample is taken adjacent to the surface by driving the sample tube its full length into the ground. The sample tube is then removed from the ground and the soil sample therein removed. The sample tube is then lowered into the previously sampled hole and the next sampling interval taken at the lower depth. Probe rods are attached to the upper end of the sample tube to transmit the percussive forces from a hammer to the sample tube at the lower depth.

[0006] Another common type of soil sampling system is known as the dual tube soil sampling system. Dual tube sampling uses two sets of probe rods to collect continuous soil cores. One set of rods is driven into the ground as an outer casing. These rods receive the driving force from the hammer and provide a sealed hole from which soil samples may be recovered without the threat of cross-contamination. The second, smaller set of rods are placed inside the outer casing. The function of these smaller rods is to hold a sample liner in place as the outer casing is driven one sampling interval. The inner rods are then retracted to retrieve the full sample liner. An example of a dual tube soil sampling system is described in U.S. Pat. No. 5,854,432.

[0007] The dual tube sampling system can also be equipped with a solid drive tip that allows an operator to start continuous coring from a desired depth below the ground surface. The solid drive tip allows the tool string to be advanced directly through undisturbed soil to the top of a desired sampling interval. The solid drive tip can be installed on the leading end of the inner probe rod string in place of the sample liner. When in place, the solid drive tip fits firmly inside and plugs the cutting shoe and effectively seals the tool string as the outer casing is driven to the desired depth.

[0008] The sample liners used in dual tube soil sampling systems are typically clear plastic cylinders that can be attached to the inner probe rod string using a liner drive head assembly. The soil sample is guided into the liner by a cutting shoe at the lower end of the outer casing of the dual tube sampling system. The liner allows easy removal and storage of the soil sample core. Further, the clear plastic material of the liner allows the different strata of the soil sample to be easily inspected while still in the liner and the relative positions of the strata are preserved.

[0009] During the collection of loose or sandy soils, it is sometimes difficult to keep the soil sample from exiting the open lower end of the sampling tube during extraction of the probe from the ground. To alleviate this problem and hold the soil sample within the sample tube, basket-type soil catcher devices have sometimes been positioned at the lower end of the tube. Such devices are designed to allow a soil sample to pass into the sample tube, but inhibit soil from passing back out of the sample tube. An example of such a basket-type soil catcher device is described in U.S. Pat. No. 5,606,139. However, the soil catcher device disclosed in the '139 patent is unsuitable for use in dual tube sampling systems. Specifically, the retainer on which the soil catcher is mounted is sandwiched between the lower end of the probe tube and the cutting shoe, thereby requiring the entire probe assembly to be removed from the soil bore and disassembled to remove the liner and soil catcher from the probe tube and cutting shoe.

[0010] A core catcher designed for dual tube sampling systems has been produced by AMS, Inc. of American Falls, Id. This core catcher slips over the outside lower end of a soil sample liner. This slip-over attachment method makes the core catcher more prone to fall off during sample retrieval. This is especially true when soil material, deposited by multiple sampling in the same hole, tends to bind the core catcher to the cutting shoe. The slip-over attachment method also creates a step at the transition area between the top most portion of the core catcher and the outside surface of the liner. The step increases the possibility that the core catcher will be pulled off, or the liner will become stuck in the cutting shoe.

[0011] Thus, there is a need in the industry for an improved soil sample liner with an attached core catcher for use in dual tube soil sampling systems.

SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to provide a soil sample liner with a permanently attached core catcher suitable for use in a dual tube soil sampling system.

[0013] It is a further object of the present invention to provide a soil sample liner assembly that prevents a soil sample from falling out of the soil sampler when the sample is retrieved to the ground surface.

[0014] It is a further object of the present invention to provide an improved soil sample liner assembly with a core catcher that can be used effectively with various soil sampling systems, that is dependable and economical to manufacture, and that is particularly well suited for use in dual tube soil sampling systems.

[0015] In order to solve the problems with the prior art described above, the applicants have developed an improved soil sample liner assembly with a core catcher permanently attached to the sample liner for use in a dual tube soil sampling system. The liner assembly includes a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending between the ends. A core catcher is positioned within the tube and permanently attached at its lower end. The core catcher includes a plurality of resilient fingers that deflect outwardly to allow soil to pass into the tube and prevent soil from falling back out. The liner assembly has its lower end supported by an inner ledge of a cutting shoe of the dual tube soil sampling system. The liner assembly with the permanently attached core catcher is removable through the upper end of the outer casing without disturbing the attachment between the cutting shoe and the outer casing while the sampling system remains in the ground.

[0016] According to a broad aspect of the present invention, a soil sample liner assembly for use in a soil sampling system is provided, comprising: a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending between the upper and lower ends; and a core catcher positioned within the tube and permanently attached to the lower end of the tube. The core catcher has a plurality of inwardly and upwardly extending resilient fingers that deflect outwardly to allow soil to pass into the tube and prevent soil from falling back out of the tube. The core catcher has an annular bottom which is substantially flush with the lower end of the tube.

[0017] According to another broad aspect of the present invention, a dual tube soil sampling system is provided, comprising: an outer tubular casing having an upper end and a lower end; a cutting shoe attached to the lower end of the outer casing, the cutting shoe having an annular inner ledge; and a soil sample liner assembly placed within the outer casing. The liner assembly has a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending therebetween. The liner assembly also has a core catcher positioned within the tube and permanently attached to the lower end of the tube. The core catcher has a plurality of inwardly and upwardly extending resilient fingers that deflect outwardly to allow soil to pass into the tube and prevent soil from falling back out of the tube. The lower end of the liner assembly is supported by the inner ledge of the cutting shoe and is removable through the upper end of the outer casing without disturbing the attachment between the cutting shoe and the outer casing. The liner assembly can be removed and replaced between successive sampling intervals while the cutting shoe and outer casing remain in the ground.

[0018] Numerous other objects of the present invention will be apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of the present invention, simply by way of illustration of one of the modes best suited to carry out the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various obvious aspects without departing from the invention. Accordingly, the drawings and description should be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will become more clearly appreciated as the disclosure of the invention is made with reference to the accompanying drawings. In the drawings:

[0020] FIG. 1 is a cross section view providing an overview of conventional dual tube soil sampling system.

[0021] FIG. 2 is a cross section view providing an overview of a dual tube soil sampling system having a core catcher permanently attached to the lower end of the soil sample liner assembly.

[0022] FIG. 3 is an enlarged detail view showing the lower end of the soil sample liner assembly shown in FIG. 2.

[0023] FIG. 4 is an exploded front view in partial section of a dual tube soil sampling system having a core catcher permanently attached to the lower end of the soil sample liner assembly according to the present invention.

[0024] FIG. 5 is a cross section view of a soil sample liner assembly having a core catcher permanently attached to the lower end of the liner tube according to the present invention.

[0025] FIG. 6 is an enlarged detail view of the lower end of the soil sample liner assembly according to the present invention.

[0026] FIG. 7 is a front view of the tube of the soil sample liner assembly of the present invention.

[0027] FIG. 8 is an end view of the tube shown in FIG. 7.

[0028] FIG. 9 is a cross section side view of a core catcher used in the soil sample liner assembly of the present invention.

[0029] FIG. 10 is an end view of the core catcher shown in FIG. 9.

[0030] FIG. 11 is a perspective view of the core catcher shown in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031] A soil sample liner assembly for a dual tube soil sampling system according to a preferred embodiment of the present invention will now be described with reference to FIGS. 2 to 11 of the accompanying drawings.

[0032] The nature of the problem to be solved by the present invention will first be explained by reference to FIGS. 1 to 3 of the drawings. In FIG. 1, a conventional dual tube soil sampling system 10 is shown having an outer casing 11, a cutting shoe 12 attached to the lower end of the outer casing 11, an inner probe rod 13, and a soil sample liner 14 coupled to the lower end of the inner probe rod 13 by a soil sample liner drive head 16. The soil sample liner 14 can be raised and lowered within the outer casing 11 by raising and lowering the inner probe rod 13.

[0033] In operation, the soil sample liner 14 in the conventional dual tube soil sampling system 10 is lowered within the outer casing 11 until the lower edge of the soil sample liner 14 engages an inner ledge 15 of the cutting shoe 12. The soil sample liner 14 is held in place against the inner ledge 15 of the cutting shoe 12 by a drive head placed over the upper end of the sampling system 10. The outer casing 11 is then driven down into the subsoil causing a soil sample 17 to pass through the cutting shoe 12 and into the soil sample liner 14. Once the outer casing 11 is driven to the desired soil sampling interval, the inner probe rod 13 and soil sample liner 14 are raised within the outer casing 11 to retrieve the soil sample 17.

[0034] The soil sample liner 14 in the conventional dual tube sampling system shown 10 in FIG. 1 has an open lower end 18. The open lower end 18 of the liner 14 often allows part of the soil sample 17 to fall out of the liner 14 and remain within the outer casing 11, particularly when sampling sandy soils or other loose soils. As a result, the soil sample liner 14 does not retrieve a complete sample, and the lower interior of the outer casing 11 tends to fill with soil interfering with additional samplings from the same bore hole.

[0035] FIGS. 2 and 3 show a dual tube sampling system 20 having an improved soil sample liner assembly 21 according to the present invention. The dual tube sampling system 20 shown in FIGS. 2 and 3 has many of the same components as the system 10 shown in FIG. 1, which are depicted by the same reference numerals as the corresponding components in FIG. 1, and will not be further described herein.

[0036] The improved soil sample liner assembly 21 has a core catcher 22 permanently attached to the lower end of the liner tube 23. The core catcher 22 allows the soil sample 24 to pass from the cutting shoe 12 into the liner tube 23, but prevents the soil sample 24 from falling back out of the liner tube 23. As a result, the soil sample liner assembly 21 can be raised within the outer casing 11 with the complete soil sample 24 remaining intact within the soil sample liner assembly 21. The soil sample liner assembly 21 is not attached to the outer casing 1 or to the cutting shoe 12. The bottom edge 25 of the liner assembly 21 merely engages and rests on the inner ledge 15 of the cutting shoe 12.

[0037] As in the conventional dual tube soil sampling system 10, the soil sample liner assembly 21 of the present invention can be removed through the top of the outer casing 11 without disturbing the attachment between the cutting shoe 12 and the outer casing 11. Once the soil sample liner assembly 21 is removed, a new soil sample liner assembly with a permanently attached core catcher can be coupled to the lower end of the inner probe rod 13 and lowered down into the outer casing 11 until the lower end of the liner assembly 21 engages and seats against the inner ledge 15 of the cutting shoe 12. The dual tube sampling system 20 is then ready to be driven further down into the subsoil to complete another soil sampling interval. The liner assembly 21 can thus be removed and replaced between successive sampling intervals while the cutting shoe 12 and outer casing 11 remain in the ground.

[0038] The various components of the dual tube sampling system 20 according to the present invention will be further described with reference to FIG. 4 of the drawings. As explained above, the system 20 includes a cutting shoe 12, an outer casing 11, a soil sample liner assembly 21, and an inner probe rod 13. The soil sample liner assembly 21 has a core catcher 22 permanently attached at its lower end. A soil sample liner drive head 26 couples the lower end of the inner probe rod 13 to the upper end of the soil sample liner assembly 21. A drive bumper 27 is attached to the upper end of the inner probe rod 13. A drive head 28 is attached to the upper end of the outer casing 11 and provides an impact surface for driving the soil sampling system 20 into the ground. The drive bumper 27 is made of a resilient material that helps cushion the impact of the drive head 28 against the inner probe rod 13 to limit stress on the soil sample liner assembly 21 as the sampling system 20 is driven into the ground. A rod clamp assembly (not shown) can be attached to the upper end of the outer casing 11 after removing the drive head 28 and drive bumper 27 to facilitate lifting the inner probe rod 13 and the soil sample liner assembly 21 from the outer casing 11.

[0039] The outer casing 11 is sometimes referred to as the outer probe rod string. The outer casing 11 comprises a plurality of tubular members which are selectively connected together end-to-end in a known manner to change a length of the outer casing 11. The inner probe rod 13 is sometimes referred to as the inner probe rod string. The inner probe rod 13 comprises a plurality of probe rods which are selectively connected together end-to-end in a known manner to change a length of the inner probe rod 13. The combined length of the inner probe rod 13 and the soil sample liner assembly 21 will normally be adjusted to approximately the same length as the outer casing 11 when the soil sampling system 21 is assembled.

[0040] As in conventional dual tube soil sampling systems, a solid drive point (not shown) can be interchanged with the soil sample liner assembly 21 and connected to the lower end of the inner probe rod 13. The solid drive point is adapted to extend at least partially through the cutting shoe 12 and seal a lower end of the outer casing 11. When assembled, the solid drive point protrudes from the lower end of the outer casing 11 and allows the sampling system 20 to be driven to the top of an initial sampling interval that begins below the ground surface.

[0041] As shown in further detail in FIGS. 5 and 6, the core catcher 22 is fit within and attached to the lower end of the soil sample liner tube 23. The core catcher 22 has a generally dome shape comprising a plurality of flexible arcuate-shaped fingers 29. The fingers 29 are preferably formed integrally with an annular bottom 30 of the core catcher 22 and project upwardly and inwardly therefrom as shown in the drawings. The fingers 29 can also be connected to the annular bottom 30 by any suitable means. The fingers 29 deflect outwardly toward the inner surface of the liner tube 23 as soil is forced into the liner assembly 21 by driving the sampling assembly 20 into the ground. After the liner tube 23 has been filled with a soil sample 24 and the inner probe rod 13 and soil sample liner assembly 21 are pulled upwardly within the outer casing 11, the fingers 29 will resume their undeflected original positions. Thus, during extraction of the soil sample liner assembly 21 from within the outer casing 11, the fingers 29 in their original undeflected positions will inhibit soil collected in the liner tube 23 from escaping through the lower portion of the liner assembly 21 and into the lower portion of the outer casing 11.

[0042] The soil sample liner tube 23 is a generally cylindrical tube having a smooth cylindrical outer surface extending between upper and lower ends 31, 32. The core catcher 22 is permanently attached to the lower end 32 of the soil sample liner tube 23 with the annular bottom 30 substantially flush with the lower end 32 and with the outside profile of the tube 23.

[0043] The soil sample liner tube 23 is preferably made of a clear thermoplastic material. The core catcher 22 is preferably formed of the same material as the soil sample liner tube 23, but can also be formed of any other suitable material capable of being securely attached to the liner tube 23 and providing the necessary resiliency. The permanent attachment of the core catcher 22 to the soil sample liner tube 23 is preferably made by welding the parts together using thermal welding or ultrasonic welding processes. The permanent attachment can also be made using adhesives (e.g., with epoxies, cyanoacrylates, etc.), riveting, or by using other suitable fastening techniques that provide a durable permanent connection. In the preferred embodiment, the soil sample liner tube 23 and core catcher 22 are both made of the same type of thermoplastic material and are permanently attached to each other using a welding process (thermal or ultrasonic) that fuses the components together. The fusion between the soil sample liner tube 23 and the core catcher 22 provides a durable assembly and minimizes the introduction of potential sample contaminants, such as glues.

[0044] It will be appreciated that certain features of the present invention described above can be changed without departing from the scope of the invention. For example, the soil sample liner assembly 21 of the present invention can be used with soil sampling systems other than dual tube soil sampling systems. Also, the particular dimensions of the components can be changed to suit a particular soil sampling system, the shape of the core catcher 22 can be different from the preferred “dome” shape shown in the drawings, the number and resiliency of the fingers 29 of the core catcher 22 can be changed, and the materials of the soil sample liner tube 23 and the core catcher 22 can be different.

[0045] While the invention has been specifically described in connection with specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.

Claims

1. A soil sample liner assembly for use in a soil sampling system, comprising:

a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending between the upper and lower ends;

a core catcher positioned within said tube and permanently attached to said lower end of said tube, said core catcher comprising a plurality of inwardly and upwardly extending resilient fingers that deflect outwardly to allow soil to pass into said tube and to prevent soil from falling back out of said tube, said core catcher having an annular bottom which is substantially flush with the lower end of said tube.

2. The soil sample liner assembly according to claim 1, wherein said resilient fingers form a dome shape within said tube.

3. The soil sample liner assembly according to claim 1, wherein said tube and said core catcher are both made of thermoplastic material.

4. The soil sample liner assembly according to claim 3, wherein said tube and said core catcher are welded together.

5. A dual tube soil sampling system, comprising:

an outer tubular casing having an upper end and a lower end;

a cutting shoe attached to the lower end of said outer casing, said cutting shoe having an annular inner ledge;

a soil sample liner assembly placed within said outer casing, said liner assembly comprising a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending therebetween;

said liner assembly further comprising a core catcher positioned within said tube and permanently attached to said lower end of said tube, said core catcher comprising a plurality of inwardly and upwardly extending resilient fingers that deflect outwardly to allow soil to pass into said tube and prevent soil from falling back out of said tube;

said liner assembly having its lower end supported by the inner ledge of said cutting shoe and being removable through the upper end of said outer casing without disturbing the attachment between the cutting shoe and the outer casing, whereby the liner assembly can be removed and replaced between successive sampling intervals while the cutting shoe and outer casing remain in the ground.

6. The dual tube soil sampling system according to claim 5, further comprising an inner probe rod coupled to the upper end of said tube of said liner assembly, said inner probe rod being operable to raise and lower said liner assembly within said outer casing.

7. The dual tube soil sampling system according to claim 6, further comprising a drive head positioned over the upper end of said outer casing, said drive head providing an impact surface for driving said soil sampling system into the ground.

8. The dual tube soil sampling system according to claim 6, wherein said outer casing comprises a plurality of tubular members which are selectively connected together end-to-end to change a length of said outer casing, and said inner probe rod comprises a plurality of probe rods selectively connected together end-to-end to change a length of said inner probe rod, whereby a combined length of the inner probe rod and the soil sample liner assembly can be adjusted to approximately the same length as the outer casing when the soil sampling system is assembled.

9. The dual tube soil sampling system according to claim 6, further comprising a solid drive point which can be interchanged with the soil sample liner assembly and connected to the lower end of the inner probe rod, said solid drive point being adapted to extend at least partially through the cutting shoe and seal a lower end of the outer casing to allow the sampling system to be driven to the top of an initial sampling interval which begins below the ground surface.

10. The dual tube soil sampling system according to claim 5, wherein said core catcher has an annular bottom which is substantially flush with an outside profile of said tube.

11. The dual tube soil sampling system according to claim 5, wherein said resilient fingers of said core catcher form a dome shape within said tube.

12. The dual tube soil sampling system according to claim 5, wherein said tube and said core catcher are both made of thermoplastic material.

13. The dual tube soil sampling system according to claim 12, wherein said tube and said core catcher are welded together.

14. The dual tube soil sampling system according to claim 5, wherein said soil sample liner assembly is not attached to said outer casing or to said cutting shoe.

15. A soil sample liner assembly for use in a dual tube soil sampling system, comprising:

a generally cylindrical tube having an upper end, a lower end, and a substantially smooth cylindrical outer surface extending between the upper and lower ends; and

a core catcher positioned within said tube and permanently attached to said lower end of said tube, said core catcher comprising a plurality of inwardly and upwardly extending resilient fingers that deflect outwardly to allow soil to pass into said tube and prevent soil from falling back out of said tube;

said core catcher having an annular bottom which is substantially flush with an outside profile of said tube, said liner assembly having a means at its lower end for engaging and resting on an annular inner ledge of a cutting shoe of the dual tube soil sampling system.

16. The soil sample liner assembly according to claim 15, wherein said resilient fingers of said core catcher form a dome shape within said tube.

17. The soil sample liner assembly according to claim 15, wherein said tube and said core catcher are both made of thermoplastic material.

18. The soil sample liner assembly according to claim 17, wherein said tube and said core catcher are welded together.