Geological probing device

Abstract

 A geological probing device (10) is disclosed. The probing device comprises a hollow probing rod (1) to be extended into the geological matter to be probed during rotation thereof, and a CPT probe (2) fitted to the probing rod (1) to be pushed into the geological matter by said probing rod. The rod (1) is arranged to rest on the CPT probe (2) during penetration thereof into the geological matter. The probing device further comprises a pressure withstanding bearing (7) arranged between the probing rod (1) and the CPT probe (2), and arranged to prevent rotation of the CPT probe during rotation of the probing rod.

Description

Technical Field

[0001] The present invention relates to a geological probing device.

Background of the Invention

[0002] Geological probing devices are used to obtain information about the soil conditions below the surface, and are known from for example US6719068, disclosing an extendable probing rod to be pushed into the soil by means of a drive mechanism.

[0003] The probing rod in US6719068 is adapted to be extended one section at a time linking a new section to the section pushed down latest when pushed into the ground. A measuring rod is fitted to the probing rod, at the tip of it, to continuously measure for example point resistance, friction, probe inclination, and water pressure while perforating the soil.

[0004] However, when pushing an extendable probing rod into the soil a rather big pressure is required due to the friction between the lateral area of the probe and the geological matter. In addition, due to the friction losses, the applied pressure is not transferred to the tip of the rod where it is needed for the rod to be able to perforate layers of harder geological matter. In order to reduce the friction, bentolite can be used as lubricant, but this leads to a more complex and expensive procedure.

[0005] Therefore, there is a need for an improved probing device that is capable of perforating harder geological matter.

Summary of the Invention

[0006] In view of the above mentioned need, a general object of the present invention is to provide a probing device that is capable of perforating harder geological matter. This and other objects are achieved through a geological probing device comprising a probing rod to be extended into the geological matter to be probed during rotation thereof; and a measuring probe fitted to the probing rod to be pushed into the geological matter by the probing rod, the probe being adapted to transmit information to a receiver located above ground. The geological probing device is characterized in that the rod is arranged to rest on the measuring probe during penetration thereof into the geological matter, the probing device further comprising a pressure withstanding bearing arrangement arranged between the probing rod and the measuring probe, and arranged to prevent rotation of the measuring probe during rotation of the probing rod.

[0007] In the context of this application geological matter means any geological matter such as clay, sand, earth or gravel, excluding solid rock.

[0008] The present invention is based on the understanding that through rotation of the probing rod, the friction on the lateral area of the probing rod that conventionally affects the rod when it is pushed into the soil is reduced. Hence, the pressure that is applied to the rod by for example a drive mechanism is transferred to the tip of the probing device. Accordingly, the probing device obtains characteristics that renders it possible to perforate layers of harder geological matter than by conventional solutions, when continuously measuring the matter by means of the CPT probe.

[0009] The fact that a greater portion of the pressure applied to the probing rod is transferred to the tip of the probing rod makes it possible to conduct measurements deeper into the geological matter for a given operating pressure, compared to conventional techniques.

[0010] Furthermore, the geological probing rod may be pushed into the geological matter with a pressure of more than 1 ton, preferably more than 10 ton, and most preferably more than 20 ton. As indicated above the present invention generally reduces force required to obtain a desired probe pressure. This will allow use of smaller and more flexible equipment for pushing the probe into the ground. This advantage is particularly important for large forces, e.g. more than 10 ton, or even more than 20 ton, where the option to use smaller equipment may result in significant cost savings. In some situations, it may be difficult or even practically impossible to transport to the probing location equipment of a size required to push a conventional probe into the ground. In such situations, the present invention may enable geotechnical probing where it was previously impossible.

[0011] Moreover, the bearing arrangement may comprise an insert member, connectable to a first section of the probing rod; and a receiving member, connectable to a second section of the probing rod and adapted to rotatably support the insert member. Alternatively, the receiving member is directly connectable to the measuring probe.

[0012] In one embodiment, the bearing arrangement may be an hydraulic bearing.

[0013] In another embodiment the receiving member may house a stack of roller bearings, which stack of roller bearings may be arranged to rotatably support the insert member, and to evenly distribute a normal force between the insert member and the receiving member between roller bearings in said stack. By roller bearing means, in the context of the present invention, any type of roller bearing, including ball bearings. The roller bearing arrangement of stacked bearings may be advantageous in that the force may be distributed over several bearings.

[0014] The invention may be useful for any CPT-system, but is particularly advantageous for a system with a wireless transmission of data from the CPT probe by means of a transmitter. Such systems include radio wave, microwave, acoustic, and optic transmission systems. Wireless transmission of data is advantageous, since cables may get entangled due to the rotation of the probing rod. Moreover, said probing rod may be hollow and act as a microwave guide.

[0015] According to another aspect of the present invention there is provided a system comprising a geological probing device and a drive mechanism for rotatingly pushing said geological probing device into the geological matter.

Brief description of the drawings

[0016] In the following, embodiments of the present invention will be described in detail, with reference to the accompanying, exemplifying drawings on which:

Figure 1 is a schematic view of a soil probing operation by means of an example of a probing device of the present invention.

Figure 2 is a perspective, and broken away, view of a probing device bearing arrangement according to a first embodiment of the present invention.

Figure 3 is a perspective, and broken away, view of a probing device bearing arrangement according to a second embodiment of the present invention.

Detailed description of preferred embodiments

[0017] Figure 1 illustrates a probing device 10 comprising a probing rod 1 assembled from segments 11 a-b which are linked together, for example by means of screw threads at the end of each section. The rod 1 in the illustrated example is hollow and typically made of steel, with standard diameter of for example 36 mm or 44 mm, making it suitable for microwave transmission as will be discussed below. Alternatively, the rod is solid, which may be suitable if transmitting information by means of acoustic waves. A measuring probe 2, here a cone penetration test, CPT, probe, conventionally an instrumented probe with a conical tip 3 adapted to perform cone penetration tests, is arranged at the tip of the probing rod 1. A basic CPT instrument is adapted to report tip resistance and shear resistance, and comprises a number of sensors. The CPT rod may comprise a compass in addition to the measuring means. Alternatively, the probe may be a mechanical CPT or an environmental probe. Here, the probing rod 1 further comprises a microwave transmitter, arranged to transmit microwaves that carries measured data. Receiving means are here fixedly arranged above the ground for receiving the data. Also, a vehicle 4 is illustrated, on which a drive mechanism 5 has been arranged capable of rotating the probing rod, and exerting a downward pressure on the probing rod in order to drill the rod into the soil. In the illustrated example, hydraulic cylinders 5 are used to push the probing rod 1 into the ground, whereas a clamp 6 is arranged to transfer the downward force and rotation to the probing rod. A bearing arrangement 7, described in detail in fig. 2, is arranged between the probing rod and the CPT rod to prevent rotation of the CPT rod during penetration of the soil.

[0018] In operation, a segment of the probing rod 1 is pushed into the soil and a further segment is linked to the top of the already pushed down segment. The clamp 6 is arranged around the rod sections protruding above the surface of the ground. As one section 11a-b is pushed further into the ground, the clamp 6 is released and then moved, in order to shift its point of application to the new rod section that was linked to the preceding section. The probing rod 1 is further rotated into the soil by the drive mechanism 5, with for example 10-15 rotations per minute.

[0019] Preferably the drive mechanism 5 allows the probing operation to continue while a new segment is linked to a precedent segment. Accordingly, the probing device 10 is forced further and further into the ground, with an essentially constant speed. Here, the CPT probe 2 is pushed in front of the rotating probing rod 1 obtaining soil data as it penetrates the soil

[0020] The data is transformed to a digital signal and supplied to the transmitter. In the illustrated example, the probing rod 1 acts as a microwave guide guiding a measured signal to the orifice of the hollow probing rod which is located above the ground, for the receiver to receive the signal, that may be recorded by a logging system. A probing device with microwave transmission is further described in US6719068, herewith fully incorporated by reference.

[0021] Accordingly, the CPT probe 2 is capable of collecting data when penetrating the soil. The direction of motion may moreover be controlled by the compass.

[0022] The fact that a large amount of the pressure applied to the probing rod by the drive mechanism 5 is transferred to the tip of the probing device 10, due to low friction losses, the device is capable of penetrating relatively hard geological matter. Accordingly, the probing device 10 may travel relatively deep into the soil, up to more than 100 meters if not meeting too hard resistance. The pressure on the bearing arrangement 7 between the probing rod 1 and the CPT rod 2 is also high, due to the low friction losses.

[0023] Turning to fig. 2, the bearing arrangement 7 may be composed as described hereinafter. An insert member 12 is adapted to, in an upper end, be connected to a connector portion 12a which in its turn is adapted to be connected to the rotating probing rod 1. A receiving member 13 is adapted to be connected to the CPT probe 2. Hence, the insert member 12 rotates with the probing rod 1, whereas the receiving member does not rotate like the PCT probe 2. The receiving member 13 is cylindrically formed and has a bore 14 rotatably supporting the insert member 12 in the bore 14, at a distance from the bottom of the bore. The cylindrically formed receiving member forms a closed compartment 16 surrounding a corresponding portion of the insert member 12, which compartment 16 is filled with an incompressible fluid, such as oil. In its lower end, the compartment 16 is sealed by a sealing member 22c, such as an o-ring, arranged in a groove in the receiving member 13 to surround the insert member 12. The upper end of the compartment 16 is closed by means of a cylindrical closing member 13a having a flange that meet the end wall of the receiving member 13, which closing member 13a surrounds a corresponding part of the insert member 12. The upper end of the compartment 16 is sealed by a sealing member 22b, such as an o-ring, arranged to surround the insert member 12.

[0024] The compartment 16 is moreover divided into two chambers 17, 18, by an annular protrusion 19 of the insert member 12. The protrusion is sealed against the inner wall 21 of the compartment 16, e.g. by an annular sealing member 22a, arranged in a groove in the protrusion 19. The annular protrusion 19 acts as a piston to prevent the insert member 12 from moving transversally in the receiving member 13. Alternatively, the protrusion 19 may be formed separately from the insert member 12, and be securely attached to the insert member 12.

[0025] Each of the two chambers 17, 18 may be supplied with oil through a respective fluid passage 24, leading through the wall of the receiving member 13. The passages may be opened when supplying of oil is required. Further, there are two wings 15a-b axially arranged on the outer surface of the receiving member 13 for adding resistance when perforating the soil, hence preventing the receiving member from rotating.

[0026] When assembling the bearing arrangement 7, first, the insert portion may be arranged in the bore 14, before the closing member 13a is passed over the insert member 12 until meeting the wall of the receiving member 13. Thereafter, the connector portion 12a may be passed over the insert member 12 until meeting the upper side of the flange of the closing member 13a, whereby the assembled parts constitute a complete bearing arrangement 7.

[0027] In operation, the insert member 12 rotates, in accordance with the rotation of the probing rod 1, in the receiving member 13 of the bearing arrangement 7. However, the insert member 12 does not move transversally, since it is secured by the annular piston 19. The receiving member is not rotating, due to that the moment is not transferred to the receiving member, when it penetrates the geological matter, and is subjected to friction.

[0028] Further, since the probing rod 1 is pushed while rotated the bearing arrangement 7 is subjected to a relatively high pressure, which is withstood by means of the oil filled space 16.

[0029] An alternative bearing arrangement 7' is illustrated in fig. 3. Similar to the bearing arrangement in fig. 2, the bearing arrangement 7' comprises an insert member 30 adapted to, at the upper end, be connected to a connector portion 30a, which in its turn is adapted to be connected to the probing rod 1. A receiving member 28, is adapted to, at its lower end, be connected to the CPT probe 2. Hence, the insert member 30 rotates in accordance with the probing rod 1, whereas the receiving member 28 is not rotating.

[0030] The receiving member 28 is cylindrically formed, i.e. forming a bore 29 adapted to receive the insert member 30. However, a second cylinder portion 29b of the receiving member 28 has a larger circumference than a first cylinder portion 29a to form a compartment 36 fitting a number of bearings 20a-e, surrounding a corresponding portion of the insert member 30. The upper end of the compartment is closed by a cylindrical closing portion 28a surrounding the insert member 30 and forming the circumference of the first cylinder portion 29a. The compartment may be oil filled for the bearing arrangement 7' to be operational, why a sealing member 40, such as an o-ring, is arranged below the bore 29 to prevent leakage. An annular load bearing surface 33 is formed by a ledge where the larger circumference narrows into the smaller circumference at the lower end of the receiving member 28. The insert member 30 has a smaller circumference, like a waist, along the portion adapted to be surrounded by bearings 20a-e. Stacked bearings, here five 20a-e, surround the waist within the second cylinder portion 29b of the receiving member 28. The primary bearing 20a is arranged on the load bearing surface 33 of the receiving member 13. Secondary bearings 20b-e are then stacked on the primary bearing 20a.

[0031] The primary bearing 20a comprises a bearing element 32, here a roller bearing, and an inner sleeve 26 with an outward directed flange 27 in its upper end, forming an annular load bearing surface 34 against the secondary bearing 20b that is stacked on the primary bearing 20a. The inner sleeve 26 of the primary bearing 20a surrounds the waist portion of a corresponding portion of the insert member 30, and the roller bearing element 32 is sandwiched in between the load bearing surface 33 or the receiving member 28, and the opposite surface of the flange 27, relative its load bearing surface 34. Here, a spring element 31, such as a cup spring, is moreover arranged between the flange 27 and the roller bearing element to distribute the force applied on the bearing.

[0032] In the illustrated example, four secondary bearings 20b-e are stacked on the primary bearing 20a. The secondary bearings 20b-e comprise identical parts as the primary bearing 20a, but additionally an outer sleeve 36 with an inward directed flange 35. In the secondary bearings 20b-e the roller bearing element 32' is arranged between a load bearing surface 37 of the inward directed flange 35 and the non-load bearing surface of the outward directed flange 27' of the inner sleeve 26'. The outer sleeve 36 surrounds the roller bearing element 32, 32', the spring element 31, 31' and the inner sleeve 26, 26' of the bearing arranged below, and rests on the same load bearing surface as this bearing. In case of the first secondary bearing 20b, the outer sleeve 36 surrounds these parts of the primary bearing 20a, whereas in the case of the second secondary bearing 20c, the outer sleeve 36 surrounds these parts of the first secondary bearing 20b, etc.

[0033] The fact that the bearings 20a-e are stacked on each other, the inner sleeves 26, 26' form a cylinder surrounding the waist of the insert member 30. The stacked outer sleeves 36, form a cylinder adjacent to the inner wall of the cylindrically formed receiving member 28.

[0034] When assembling the bearing arrangement 7' illustrated in figure 3, the stacked bearings 20a-e may be arranged in the bore 29 of the receiving member 28, and the insert member 30 be inserted into the stack. Alternatively, the bearings 20a-e are stacked around the waist of the insert member 30 before it is inserted into the bore 29. The cylindrical closing portion 28a may thereafter be passed over the insert member 30 to be arranged in the space between the inner surface of the bore 29 and the insert portion 30 to close the compartment 36. Finally, the connector portion 30a is arranged, so as to connect the insert member 30 and the probing rod 1.

[0035] In operation, the insert member 30 rotates with the probing rod 1 in the receiving member 28 of the bearing arrangement 7'. The bearing arrangement 7'ensures that no rotational force is transferred to the receiving member, while at the same time distributing the normal force between all the bearings 32, 32' in the stack. The person skilled in the art realizes that the present invention is not limited to the preferred embodiments. For example, the bearing may be another type of bearing, such as a stacked ball bearing, an hydraulic stacked bearing etc. Such and other obvious modifications must be considered to be within the scope of the present invention, as it is defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word "comprising" does not exclude the presence of other elements or steps than those listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Further, a single unit may perform the functions of several means recited in the claims.

Claims

1. A geological probing device (10) comprising
a probing rod (1) to be extended into the geological matter to be probed during rotation thereof; and
a measuring probe (2) fitted to the probing rod (1) to be pushed into the geological matter by said probing rod (1), said measuring probe (2) being adapted to transmit information to a receiver located above ground,
characterized in that the probing rod (1) is arranged to rest on the measuring probe (2) during penetration thereof into the geological matter,
the probing device (10) further comprising a pressure withstanding bearing arrangement (7, 7') arranged between the probing rod (1) and the measuring probe (2), and arranged to prevent rotation of the measuring probe (2) during rotation of the probing rod (1).

2. The geological probing device (10) according to claim 1, wherein said probing rod (1) is pushed into the geological matter with a pressure of more than 1 ton, preferably more than 10 ton, and most preferably more than 20 ton.

3. The geological probing device (10) according to any of the preceding claims, wherein said bearing arrangement (7, 7') comprises
an insert member (12, 30), connectable to a first section (11a) of the probing rod (1); and
a receiving member (13, 28), connectable to a second section (11b) of the probing rod (1) and adapted to rotatably support the insert member (12, 30).

4. The geological probing device (10) according to claim 3, wherein said receiving member (13) is a cylinder forming a closed compartment (16) surrounding a corresponding portion of said insert member (12), which compartment (16) is filled with a fluid and divided into a first (17) and a second (18) chamber by an annular protrusion (19) of the insert member (12), sealed against an inner wall of the compartment (16),
said annular protrusion (19) acting as a piston to prevent transversal movement of the insert member (12) in relation to the receiving member (13).

5. The geological probing device according to claim 3, wherein said receiving member (28) houses a stack of roller bearings (20a-e), which stack of roller bearings is arranged to rotataably support the insert member (30), and to evenly distribute a normal force between the insert member (30) and the receiving member (28) between roller bearings (20a-e) in said stack.

6. The geological probing device (10) according to claim 4, wherein said roller bearing stack (20a-e) comprises a primary bearing (20a) and a secondary bearing (20b),
said primary bearing (20a) including:

an inner sleeve (26) surrounding the insert member (30) and having an outwardly directed flange (27) in its upper end,

a roller bearing element (32) sandwiched between the flange (27) of the inner sleeve (26) and a load bearing surface (33) of the receiving member (28),

said secondary bearing (20b) including:

an inner sleeve (26') surrounding the insert member (30) and having an outwardly directed flange (27') in its upper end,

an outer sleeve (36) surrounding the inner sleeve and having an inwardly directed flange (35) in its upper end,

a roller bearing element (32') sandwiched between the flange (27') of the inner sleeve (26') and the flange (35) of the outer sleeve,

wherein the inner sleeve (26') of said secondary bearing (20b) rests on the inner sleeve (26) of said primary bearing (20a), and wherein the outer sleeve (36) of said secondary bearing rests on said load bearing surface (33).

7. The geological probing device (10) according to claim 5, wherein said roller bearing stack (20a-e) comprises several secondary bearings (20be) stacked on each other.

8. The geological probing device (10) according to any of the preceding claims, wherein the measuring probe (2) comprises a transmitter adapted to wirelessly transmit data measured by said measuring probe (2).

9. The geological probing device according to claim 7, wherein said transmitter is a microwave transmitter, and wherein said probing rod (1) is hollow and adapted to act as a microwave guide.

10. A system comprising a geological probing device (10) according to claim 1 and a drive mechanism (5) for rotatingly pushing said geological probing device (10) into the geological matter.

Drawing