Heat flow penetrometer and manufacturing method thereof

Abstract

A heat flow cone penetrometer (CPT) system (1) for measuring subterranean thermal conductivity is provided, comprising a penetrometer (2), a pusher (3) and at least one heat flow module (4). The at least one heat flow module (4) comprises at least one heating means (41) and at least one temperature sensor (42). The at least one flow module (4) comprises a dissipative sleeve (43) surrounding an inner sleeve (44), wherein the inner sleeve (44) comprises the heating element (41).

Description

Technical Field

[0001] The present disclosure generally relates to a heat flow penetrometer test system for measuring the thermal conductivity of the subsurface, and more particularly, to a heat flow module for a heat flow penetrometer system, a method of manufacturing a heat flow penetrometer system, a method of determining the subsurface thermal conductivity, and a parts kit for manufacturing and using a heat flow penetrometer system. Unleashing insights from geospatial data, the invention further relates to improvements in sustainability and environmental development: Together, we create a safe and livable world. Background Art

[0002] There is a general and ongoing need to improve the quality of data collection for subsurface surveys. Subsurface features are determined to identify objects below the surface, and soil characteristics such as soil type, density, water content, shear modulus, etc. are determined, which can be used for foundation planning and / or management. Subsurface information can be used, for example, for site characterization of infrastructure projects, foundation calculations, etc. For such applications, it is important to generate a highly accurate and comprehensive understanding of the subsurface in an efficient manner.

[0003] One of the methods for performing such tests is called the cone penetration test (CPT). Cone penetration is a geotechnical investigation method for determining soil and groundwater properties, in which a cone penetrometer is pushed into the soil for measurement. Typical parameters measured by the probe are cone tip resistance, sleeve friction, and pore water pressure. Generally, the test method involves pushing the instrumented cone penetrometer tip downward into the ground at a controlled speed.

[0004] There is a need to determine the thermal properties of soil. One such property is the thermal conductivity of the soil, which provides a measure of the energy dissipation through the soil. The thermal conductivity of a material is a measure of the ability of the material to conduct heat, and it is defined as the energy transfer due to the random motion of molecules across a temperature gradient. This is an important property to determine, as it affects, for example, foundation design, cable routing and cable design, insulation properties of subsurface structures, etc. The measurement of heat conduction affects, for example, how quickly the heat generated in a power cable and / or a data cable can dissipate, thus preventing such cables from overheating. The optimal cable routing may also be affected by the measurement of heat dissipation, such that the thermal conductivity of the soil in the selected routing does not have a negative impact on the operating characteristics of the cable.

[0005] A known method of performing such CPT is to use a cone penetrometer assembly consisting of multiple rod segments, thus forming a string of rods, and the cone penetrometer is positioned at the tip, which enables measurements to be made at the desired depth. Other known methods utilize a coiled CPT system, where a slender push rod is used, and where the push rod is bent into a coiled shape such that the push rod can be straightened before being pushed into the soil. Conventional CPT systems do not provide the possibility of measuring thermal conductivity.

[0006] Attempts have been made to produce CPT systems that allow the determination of thermal conductivity. Known CPT systems include a cone penetrometer that has a friction sleeve positioned between the cone and the push rod, and the friction sleeve is arranged to be heated by frictional heating when the CPT system is advanced into the soil. When the CPT system is advanced into the soil, the cone penetrometer starts to heat up and store a certain amount of energy. Once the cone penetrometer reaches certain temperatures, the advancement of the CPT system stops so that no further friction-induced energy is supplied to the system. When the temperature of the cone penetrometer is higher than the temperature of the surrounding soil, the cone penetrometer starts to release heat to the surrounding soil. The rate at which the temperature of the cone penetrometer decreases indicates the thermal conductivity of the soil surrounding the CPT system. If the soil has a high thermal conductivity, the heat dissipates at a higher rate, resulting in a higher average temperature difference and thus a greater decrease in the temperature of the cone penetrometer. A thermometer is generally positioned in the cone of the cone penetrometer, which measures the decrease in temperature of the cone and the friction sleeve after heating by friction with the soil.

[0007] In particular, the rate of decrease in the temperature gradient between the cone penetrometer and the soil is determined by the heat dissipation through the soil, i.e., the thermal conductivity. If the soil heats up but cannot dissipate energy quickly, the temperature of the soil directly surrounding the cone penetrometer will increase, causing the temperature difference between the cone penetrometer and the soil to decrease and the rate of temperature decrease of the cone penetrometer to flatten out. Therefore, the temperature drop of the cone penetrometer is less steep, providing information about the low thermal conductivity of the soil. Similarly, if the rate of energy dissipation is very high, i.e., the rate of temperature decrease of the cone penetrometer is high, the thermal conductivity of the surrounding soil is high.

[0008] One problem associated with known cone penetrometers is that the heating caused by soil friction generally requires a temperature change of at least 3°C, which roughly corresponds to a cone resistance of at least 3 MPa when advancing through the soil by at least approximately 1 m. If the cone resistance provided by the soil is low, the temperature required for accurate measurement cannot be achieved. Therefore, such passive CPT systems cannot be used for these softer soils because the softer soils cannot provide sufficient cone resistance. In addition, even if enough heat is generated at greater depths, this reduces the measurement resolution of the CPT system because it requires a longer travel path into the soil to generate enough heat to perform the test. Additionally, since the CPT system only includes a single thermometer in the cone of the CPT system, the time required to perform the test over a relevant section of the soil is very long.

[0009] To alleviate the problem of measuring thermal conductivity in softer soils, a known approach is to utilize a thermal - flow needle. This is a thin, elongated needle provided at the tip of an in - situ probe. Such a thermal - flow needle is provided on the in - situ probe and does not measure cone resistance and sleeve friction, thus requiring additional tests and more expensive additional soil - testing procedures. This needle is actively heated and thus is not dependent on friction - induced heating. The needle is used because it defines an aspect ratio of length relative to its diameter, which allows for modeling of thermal conductivity under the assumption that the needle is defined as an infinite - line model, which has an analytical solution for energy dissipation. The needle must have a small diameter - to - length ratio; otherwise, the needle does not conform to the infinite - line model. Solving for the thermal conductivity of a short cylinder based on the analytical solution would require a measurement time much longer than what is reasonably feasible. However, due to the very small diameter of the thermal - flow needle, it is fragile and cannot be used in harder soils. Additionally, similar to friction - induced thermal CPT systems, a single thermal - flow needle takes a long time to measure soil properties over a certain depth range.

[0010] Since the thermal - flow needle cannot be utilized in harder soils, it cannot measure the hard layer covering the soft layer. That is, a robust friction - sleeve system can reach the underlying soft layer, but because the heat due to friction is too low, this system cannot measure in soft soils. The thermal - flow needle system first cannot penetrate the hard soil and thus cannot reach the underlying soft soil. One option is to form a borehole to push the needle into the soft soil through the borehole. However, this is very expensive and inefficient.

[0011] Thus, the prior art for cone penetration testing does not provide a solution for collecting high - quality data containing thermal conductivity in different types of soils.

[0012] Accordingly, there is a need for an improved cone penetrometer system and a method of performing a cone penetrometer test that solves the above - mentioned problems and provides information about the thermal properties of the target soil. SUMMARY OF THE INVENTION

[0013] In one aspect of the present invention, there is provided a thermal - flow penetrometer test system for measuring subsurface thermal conductivity. The thermal - flow penetrometer system includes a penetrometer extending between a tip and a proximal end. The thermal - flow penetrometer further includes a push rod arranged to transfer a compressive force to the penetrometer and having a connecting section. The thermal - flow penetrometer further includes at least one thermal - flow module provided between the proximal end of the penetrometer and the connecting section of the push rod. According to the present disclosure, the at least one thermal - flow module includes at least one heating element and at least one temperature sensor.

[0014] In advantageous embodiments, the penetrometer is a cone penetrometer. The penetrometer can be a virtual penetrometer of any shape. The penetrometer can be a virtual penetrometer without measurement capabilities. Advantageously, the penetrometer can contain measurement equipment such as that generally understood as standard equipment in CPT measurements. In advantageous embodiments, the penetrometer has a shape that allows penetration into the soil with reduced push rod pressure and / or soil resistance. In an embodiment, the penetrometer can have a substantially flat tip surface. The penetrometer can have a substantially hemispherical tip surface. In advantageous embodiments, the penetrometer includes a conical tip. Hereinafter, reference may be made to a CPT system, i.e., a cone penetration test system. All embodiments described in the context of the present disclosure can be used in combination with any penetrometer tip shape and are not limited to the conventional conical shape.

[0015] By using at least one heat flux module having a heating element and a temperature sensor, the system can be used for many different types of soil. The heating element can be a heating wire, a chemical heating element, etc. The heating element can be formed as a flat plate having a resistance such that electrical energy is converted into heat. The heating element can be integrally formed with the heat flux module or detachably coupled to the heat flux module. In advantageous embodiments, the heating element includes an elongated wire. The heat flux module can also be provided around the push rod or partially around the push rod. The heat flux module should include a section capable of converting the compressive force required to drive the CPT system into the target soil. To this end, the push rod extends through the heat flux module, or the heat flux module includes a strengthening section that is arranged to transfer the compressive force to the cone. The heat flux module can advantageously be disconnected from the CPT system. Alternatively, the heat flux module can be integrally formed with the cone penetrometer.

[0016] In the context of the present disclosure, the subsurface is understood to include any area, whether shallow or deep, below the surface of the earth. It should not be limited to a specific area of subsurface soil. It can refer to soil below the surface of the land or sea, i.e., soil below the seabed or below the ground level.

[0017] The cone penetration test in the context of the present disclosure can be performed on land and at sea where applicable. In the context of the present disclosure, the soil can be derived from any type of onshore and offshore ground. In the context of the present invention, the term "ground" should be understood to mean any terrain, whether on land or underwater. The device according to the present invention can be used to test onshore and offshore soil. The terms ocean, seabed or sea floor can be understood broadly and in the context of the present disclosure refer to any underwater ground including but not limited to lakes, ponds, rivers, seas and oceans.

[0018] Advantageously, the heat flux cone penetrometer can provide information that allows the determination of the heat capacity value by using empirical relationships in the literature for estimation.

[0019] In an advantageous embodiment, the diameter of the heat flux module is substantially equal to the diameter of the cone penetrometer. In an embodiment, the diameter of the heat flux module is substantially equal to the approximate average diameter of the entire CPT system including the penetrometer and the push rod.

[0020] The diameter of the heat flux module being substantially equal to the diameter of the cone penetrometer advantageously results in measuring a larger volume of soil. The present invention provides a heat flux module with a larger contact surface with the soil as compared to a heat flux needle system. This increased soil volume results in greater heat dissipation, thereby improving the measurement accuracy.

[0021] In one embodiment, the heat flux cone penetrometer system includes at least two heat flux modules, advantageously including at least 3 heat flux modules.

[0022] In one embodiment, the heat flux cone penetrometer system may include at least 4 heat flux modules, advantageously at least 5 heat flux modules, more advantageously at least 6 heat flux modules. The use of multiple heat flux modules advantageously allows for simultaneous measurement of the thermal conductivity of the soil at multiple locations. The heat flux cone penetrometer system is advanced into the soil and stopped at an appropriate depth to obtain measurement values. Two or more heat flux modules provided in the heat flux cone penetrometer system can perform thermal conductivity measurements simultaneously and provide a larger amount of soil information in a shorter period of time. Thus, by using multiple heat flux modules in the heat flux cone penetrometer system, the data acquisition process becomes more efficient.

[0023] In one embodiment, the heat flux module includes a dissipation sleeve and an inner sleeve, the dissipation sleeve being provided around the inner sleeve, and wherein the inner sleeve includes a heating element.

[0024] In one embodiment, the heat flux cone penetrometer system includes at least two heat flux modules. In one embodiment, one or more heat flux modules each include a dissipation sleeve and an inner sleeve, the dissipation sleeve being provided around the inner sleeve, and wherein the inner sleeve includes a heating element. The inner sleeves are advantageously spaced apart in the axial direction extending along the push rod and the cone penetrometer. In an advantageous embodiment, the distance between the first inner sleeve and the second inner sleeve is between approximately 1 cm and 50 cm, advantageously between approximately 2 cm and 40 cm, more advantageously between approximately 5 cm and 30 cm, still more advantageously approximately 10 cm.

[0025] Advantageously, the spacing of the inner sleeves in the heat flux module is selected such that the desired measurement resolution is obtained without interfering with the heat sources of different heat flux modules.

[0026] In one embodiment, the at least one inner sleeve defines a length between approximately 3 cm and 30 cm, advantageously between approximately 5 cm and 25 cm, more advantageously between approximately 10 and 20 cm, still more advantageously approximately 15 cm.

[0027] In the heat flux module, the inner sleeve has a relatively short maximum length, allowing for improved resolution in thermal conductivity measurements. Conversely, if a single elongated heat flux module with a single inner sleeve is used, a large temperature front will form. Thus, the dissipation sleeve of the heat flux module will be affected by several small layers in the soil, for example, layers with a thickness of approximately 20 cm. The use of several thermally insulated heat flux modules makes it possible to measure the thermal conductivity of a single smaller layer. The properties in a single thin layer are measured with a greater variation as the module is shorter, thereby improving the resolution. In a homogeneous soil unit, multiple measurements can help quantify the reliability and repeatability of the measurements and / or local variations within a soil unit.

[0028] In one embodiment, the at least one heat flux module defines the distance to the tip of the cone penetrometer to be between approximately 10 cm and 1 m, advantageously between approximately 20 cm and 80 cm, more advantageously between approximately 25 cm and 60 cm, still more advantageously between approximately 30 cm and 50 cm.

[0029] Advantageously, the at least one heat flux module is positioned close to the tip of the cone penetrometer. The heat generated by soil friction can help heat the heat flux module, thus requiring less time for the temperature of the heat flux module to increase. Additionally, by providing the heat flux module at a certain distance from the tip of the cone penetrometer, a standard cone penetrometer can be used, which does not require further modification. Additionally, the spacing between the heat flux module and the tip of the cone penetrometer can allow additional space for the electronics to accommodate the heat flux module and the cone penetrometer, as well as for any connection units that can advantageously be provided between the heat flux module and the cone penetrometer.

[0030] By providing the inner sleeve and the dissipation sleeve as separate components of the heat flux module, the heating element can be embedded in the inner sleeve and positioned within the dissipation sleeve. Thus, the inner sleeve and its components are protected from the soil through which the CPT system is advanced. Therefore, the material selection can be optimally chosen to meet the thermal requirements. For example, a highly conductive material with relatively low resistance to mechanical wear can be selected for the inner sleeve, while the dissipation sleeve includes a material with higher wear resistance. In one embodiment, the inner sleeve includes at least one of aluminum, copper, gold, silver, graphite, and technical ceramics. In a preferred embodiment, the inner sleeve includes aluminum. In one embodiment, the dissipation sleeve includes steel, advantageously hardened steel. In one embodiment, the dissipation sleeve includes nitrided steel and / or ceramics. Additionally, the protection of the inner sleeve further allows the heating element to be incorporated into the inner sleeve in a thermally optimal manner without having to consider the wear forces on the CPT system.

[0031] In one embodiment, the inner sleeve comprises aluminum. Since aluminum conducts heat well, the use of aluminum is advantageous for the inner sleeve. Other types of metals and / or other heat-conductive materials such as graphite can also be used. In one embodiment, the dissipation sleeve comprises hardened stainless steel. The use of hardened stainless steel advantageously limits wear through soil friction.

[0032] In one embodiment, the dissipation sleeve comprises a wear-resistant material, advantageously a metal. In one embodiment, the dissipation sleeve comprises stainless steel, advantageously hardened stainless steel. The use of the wear-resistant material helps reduce mechanical wear of the dissipation sleeve, thereby improving structural integrity. The use of steel, advantageously stainless steel, helps prevent the formation of an insulating oxide layer between the dissipation sleeve and the inner sleeve. Preventing such oxidation maintains optimal heat transfer.

[0033] In one embodiment, the heating element comprises a heating wire provided over the outer surface of the inner sleeve. In an advantageous embodiment, the inner sleeve comprises a helical groove for receiving the heating wire. In one embodiment, the groove is provided on the outer surface of the inner sleeve. Alternatively or additionally, a groove for receiving the heating wire can be provided on the inner surface of the inner sleeve.

[0034] The use of the helical groove ensures that a single wire can be used while substantially covering the entire surface of the inner sleeve. In an alternative embodiment, two or more heating wires can be utilized in the same or separate grooves over the inner sleeve. Advantageously, a thermal paste is provided between the inner sleeve and the dissipation sleeve. Such thermal paste can contribute to uniform heating of the inner sleeve and the dissipation sleeve. The number of turns around the inner sleeve can further affect the heating uniformity of the heat dissipation module. For example, if a thermal paste is used, the grooves defining the turns around the inner sleeve can be further spaced apart to obtain a similar level of heating uniformity. In one embodiment, the dissipation sleeve and the inner sleeve can be pressed together such that no space is defined therebetween. This limits the risk of an insulating air layer existing between the inner sleeve and the dissipation sleeve. In an alternative embodiment, the inner sleeve and the dissipation sleeve are integrally formed.

[0035] To achieve uniform heating of the inner sleeve and the heat dissipation module, advantageously, a helical heating wire having several turns can be used as the heating element. In combination with a highly conductive material such as aluminum for the inner sleeve, heat dissipation through the dissipation sleeve and the inner sleeve heat dissipation module increases, resulting in a more uniform temperature distribution across the entire dissipation sleeve and the inner sleeve. In an advantageous embodiment, a thermal paste can be utilized between the inner sleeve and the dissipation sleeve, which further contributes to heat dissipation between the dissipation sleeve and the inner sleeve.

[0036] In one embodiment, the inner sleeve includes at least one slot to accommodate the temperature sensor. In one embodiment, the inner sleeve includes at least one hole, and the at least one hole is arranged such that the heating wire and / or the data wire of the temperature sensor can extend through the hole. In one embodiment, the heating wire passes through a first hole, and the data wire of the temperature sensor passes through another hole. Since heat is generated by the heating wire, it may be advantageous to separate the heating wire and the data wire. In an alternative embodiment, the heating wire and the data wire extend through the same hole. Additional access holes may be provided in the inner sleeve such that the inner region of the inner sleeve can be reached even after the data wire and the heating wire have been installed and extend through the at least one hole.

[0037] In one embodiment, the heat flux penetrometer system further includes an electronic control unit, which is arranged to control the temperature sensor and / or the heating element. In one embodiment, the electronic control unit only controls the heating element such that the temperature sensor automatically measures and stores and / or transmits the measurement results. The electronic control unit can also be arranged to provide communication between all sensors and the control software. In addition, the electronic control unit can measure the output change of the sensor and advantageously convert these measured electrical values into, for example, temperature values. In an advantageous embodiment, the electronic control unit measures temperature, current, and / or voltage. The electronic control unit can be provided in the middle region of the heat flux module such that it is provided within the inner sleeve of the heat flux module. In one embodiment, each heat flux module includes an electronic control unit. In an alternative embodiment, the heat flux penetrometer system includes a single electronic control unit, which is arranged to control a plurality of heat flux modules.

[0038] In one embodiment, the heat flux module includes at least one insulating ring, which is provided at the distal end of the heat flux module. In one embodiment, the insulating ring includes plastic, advantageously polyetheretherketone (PEEK). In one embodiment, the insulating ring includes at least one of rubber, non-thermally conductive and / or insulating plastic (such as polytetrafluoroethylene), and insulating glass-filled plastic. In one embodiment, the insulating ring includes ceramic. Advantageously, the insulating ring is used to help prevent heat loss in the axial direction of the heat flux penetrometer system to the rods above and below the inner sleeve. Additionally, the insulating ring can be arranged such that the inner sleeve and the dissipation sleeve are supported by the insulating ring.

[0039] In such embodiments, the insulating ring may be arranged such that a thermal barrier is defined between the inner sleeve and the inner core of the heat flow CPT, to prevent heat loss of the inner core of the CPT system in the radial direction. This helps protect any components of the CPT system in the rod from excessive heat generated by the inner sleeve, and conserve energy so that a greater proportion of the energy is dissipated into the target soil. In advantageous embodiments, two insulating rings are included in each heat flow module, one insulating ring positioned below each of the heat flow modules, and one insulating ring positioned above each of the heat flow modules. In one embodiment, the heat flow modules may share insulating rings such that the lower insulating ring of one heat flow module is the upper insulating ring of another heat flow module. Thus, all heat flow modules are thermally insulated from the remainder of the CPT system.

[0040] According to one aspect of the invention, there is provided a heat flow module for a heat flow cone penetration test (CPT) system. Any of the embodiments of the heat flow module described with respect to the heat flow CPT system may be applied to this aspect of the invention. The heat flow module advantageously includes a dissipation sleeve and an inner sleeve. In one embodiment, the dissipation sleeve is provided around the inner sleeve. Advantageously, the inner sleeve includes a temperature sensor. The temperature sensor measures a decrease or increase in temperature of the heat flow module such that heat dissipation through the soil can be determined. Advantageously, the heat flow module is arranged for use in a heat flow CPT system according to any of the embodiments disclosed herein.

[0041] According to one aspect of the invention, there is provided a method of manufacturing a heat flow CPT system, the method comprising the steps of: providing a cone penetrometer; providing a push rod; providing at least one heat flow module; and attaching the at least one heat flow module between the cone penetrometer and the push rod to form a heat CPT system according to any of the embodiments of the present disclosure.

[0042] According to one aspect of the invention, there is provided a method of determining the underground thermal conductivity, the method comprising the steps of: providing a heat flow CPT system according to any of the embodiments of the present disclosure; advancing the heat flow CPT into the target soil; heating the heat flow module by providing power to a heating element of the heat flow module; and measuring the temperature of the heat flow module using the temperature sensor of the heat flow module as the heat flow module is cooled by the surrounding target soil to determine the temperature gradient as a function of time.

[0043] In one embodiment, the step of heating the heat flow module includes providing a variable voltage input such that a constant power output is provided. The use of a variable voltage input allows the heating element to provide a constant power output. As the temperature increases, the resistivity of a heating element such as a heating wire will decrease. Therefore, the input voltage must be changed to allow a constant (heating) power output over time. This allows for a more accurate determination of the thermal conductivity of the surrounding soil. In advantageous embodiments, the power output is controlled by an electronic control unit.

[0044] The heat flow into the surrounding soil from the heat flow module depends on the temperature gradient between the two. As the surrounding soil dissipates the energy from the heat flow module, the temperature of the heat flow module decreases and the temperature gradient also decreases. The rate at which the temperature gradient decreases depends on the energy dissipation through the soil and the total amount of energy in the heat flow module. Thus, knowing the amount of energy in the heat flow module allows for a more accurate determination of the dissipation through the soil. In an alternative or additional embodiment, the temperature is monitored during heating of the inner sleeve such that the heating of the soil is measured.

[0045] According to one aspect of the invention, there is provided a kit of parts for producing and using a heat flow cone penetrometer system according to any one of the embodiments of the invention herein, comprising a cone penetrometer, a push rod, and at least one heat flow module.

[0046] Advantageously, the kit of parts is arranged for producing and using a heat flow cone penetrometer system according to any one of the embodiments disclosed herein. Further features and advantages of the present disclosure will be set forth throughout the disclosure, and in part will be obvious from the description, or may be learned by practice of the principles disclosed herein. The features and advantages of the present disclosure may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] To describe the manner in which the above-described and other advantages and features of the present disclosure can be obtained, a more particular description of the principles briefly described above will be presented by reference to specific embodiments illustrated in the accompanying drawings. It is to be understood that these drawings depict only exemplary embodiments of the present disclosure and are not to be considered limiting of its scope, and the principles herein are depicted and described with additional specificity and detail by the use of the drawings, in which:

[0048] Figure 1 is a side view of a heat flow cone penetrometer system according to an embodiment of the invention;

[0049] Figure 2 is a cross-sectional view of a heat flow cone penetrometer system according to an embodiment of the invention;

[0050] Figure 3 is a three-dimensional view of the inner sleeve of the heat flow module in a heat flow cone penetrometer system according to an embodiment of the invention; and

[0051] Figure 4 is a three-dimensional cross-sectional view of a portion of a heat flow cone penetrometer system according to an embodiment of the invention, showing the heat flow module. DETAILED DESCRIPTION

[0052] The following is a description of certain embodiments of the invention given by way of example only and with reference to the drawings.

[0053] The various embodiments of the present disclosure are discussed in detail below. Although specific implementations are discussed, it should be understood that this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the spirit and scope of the present disclosure. Accordingly, the following description and drawings are illustrative and should not be construed as restrictive. Many specific details are described to provide a thorough understanding of the present disclosure. However, in some instances, well-known or conventional details are not described to avoid obscuring the description. References to embodiments in the present disclosure may refer to the same embodiment or any other embodiment. Thus, such references relate to at least one of the embodiments herein.

[0054] Reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The phrase "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive of other embodiments. Additionally, various features are described that may be exhibited by some embodiments and not by others.

[0055] The terms used in this specification generally have their ordinary meanings in the art, in the context of the present disclosure, and in the particular context in which each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be attributed to whether a term is elaborated or discussed herein. In some instances, synonyms for certain terms are provided. The recitation of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification, including examples of any of the terms discussed herein, is illustrative only and is not intended to further limit the scope and meaning of the present disclosure or any example term. Similarly, the present disclosure is not limited to the various embodiments given in this specification.

[0056] Examples of instruments, devices, methods, and their associated results according to embodiments of the present disclosure are given below, and are not intended to limit the scope of the present disclosure. It should be noted that, for the convenience of the reader, headings or subheadings may be used in the examples, which should in no way limit the scope of the present disclosure. Unless otherwise defined, the technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art to which the present disclosure pertains. In case of conflict, the present document containing the definitions shall prevail.

[0057] Additional features and advantages of the present disclosure will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the principles disclosed herein. The features and advantages of the present disclosure may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. These and other features of the present disclosure will become more fully apparent from the following description and appended claims, or may be learned by practice of the principles set forth herein.

[0058] Reference Figure 1 , a side view of a heat flux cone penetrometer system 1 according to an embodiment of the present invention is shown. The heat flux cone penetrometer system 1 is arranged to measure the in-situ thermal conductivity. The heat flux cone penetrometer system 1 includes a cone penetrometer 2. The cone penetrometer can be a standard cone penetrometer commonly used in the industry. The cone penetrometer 2 extends between a tip 21 and a proximal end 22. The heat flux cone penetrometer system 1 further includes a push rod 3 which is arranged to transfer a compressive force to the cone penetrometer 2 when the cone penetrometer 2 is driven into the target soil. The push rod 3 includes a connecting section 31. The connecting section 31 of the push rod 3 is arranged to couple the push rod 3 to a component of the heat flux cone penetrometer system 1.

[0059] The heat flux cone penetrometer system 1 in the illustrated embodiment includes three heat flux modules 4 separated by an intermediate section 7. The heat flux modules 4 are provided between the proximal end 22 of the cone penetrometer 2 and the connecting section 31 of the push rod 3. Each of the heat flux modules 4 in the illustrated embodiment includes at least one heating element 41 and at least one temperature sensor 42.

[0060] Between the heat flux modules 4 in the illustrated embodiment, a plurality of insulating rings 6 are provided. Such insulating rings 6 are arranged to insulate the heat flux modules from each other such that the heat generated by the first heat flux module 4 does not affect the temperature measurement of the temperature sensor 42 of the second heat flux module 4.

[0061] The heat flux modules 4 are stacked axially between the cone penetrometer 2 and the connecting section 31 of the push rod 3. The heat flux cone penetrometer system 1 may include more or fewer heat flux modules 4 so that it can be adapted to achieve sufficient resolution of heat dissipation in the target soil, and / or increase the total range of the measurement depth in one measurement cycle.

[0062] Now reference Figure 2 , a cross-sectional view of the heat flux cone penetrometer system 1 according to an embodiment of the present invention is shown. For purposes of illustration, Figure 2Only a single heat flux module 4 between the connecting section 31 of the push rod 3 and the proximal end 22 of the cone penetrometer 2 is shown. The heat flux module 4 includes a dissipation sleeve 43 and an inner sleeve 44. The dissipation sleeve 43 is provided around the inner sleeve 44. The inner sleeve 44 includes a heating element 41. In this case, the heating element 41 is a heating wire that is wound around the inner sleeve 44 through grooves provided on the outer surface of the inner sleeve 44.

[0063] The heat flux module 4 further includes a temperature sensor 42 that is received in a slot on the outer surface of the inner sleeve 44. The heat generated by the heating element 41 in the form of the heating wire 41 provided in the grooves on the outer surface of the inner sleeve is distributed through the inner sleeve 44 and the dissipation sleeve 43 provided around the inner sleeve 44. Once the measurement starts, the heat generated by the heating wire 41 stops, and then the temperature sensor 42 measures the temperature drop as the heat dissipates from the inner sleeve into the soil. In an alternative embodiment, the measurement is performed during the heating of the heating wire 41 such that the measurement by the temperature sensor 42 is carried out simultaneously with the start of heat generation by the heating wire 41.

[0064] The heat flux module 4 further includes an electronic control unit 5 that is provided in the middle of the heat flux module 4 such that it extends through the inner sleeve 44. The electronic control unit 5 is arranged to control the heat provided by the heating wire 41 and retrieve the measurement results from the temperature sensor 42 when measuring the heat dissipation through the soil.

[0065] Insulating rings 6 are provided at both ends of the heat flux module 4. The insulating rings 6 are used to help prevent heat loss to the rods above and below the inner sleeve 44 in the axial direction of the heat flux cone penetrometer system 1. Additionally, the insulating rings 6 are arranged such that the inner sleeve 44 and the dissipation sleeve 43 are supported by the insulating rings 6. Thus, an insulating air gap is defined between the inner sleeve 44 and the inner core of the heat flux cone penetrometer system 1 to prevent heat loss of the core of the CPT system in the radial direction.

[0066] Now referring to Figure 3 , a three-dimensional view of the inner sleeve 44 of the heat flux module 4 in the heat flux cone penetrometer system 1 according to an embodiment of the present invention is shown. The inner sleeve 44 of the illustrated embodiment includes a set of two offset spiral grooves 47 that are arranged to receive the heating wire 41. The inner sleeve further includes a plurality of slots 45 that are arranged to receive the temperature sensors 42. These temperature sensors 42 are arranged to measure the temperature change of the heat flux module 4 to determine the heat dissipation through the target soil.

[0067] The inner sleeve 44 of the illustrated embodiment further includes a hole 46 that extends from the outer surface of the inner sleeve 44 through the inner sleeve 44 to the inner surface of the inner sleeve 44. The hole 46 is arranged to receive a heating wire 41, which can extend through the hole 46 and through the inner sleeve 44 such that the heating wire 41 can be controlled and power can be provided from within the inner sleeve 44 provided with the electronic control unit 5.

[0068] The inner sleeve 44 further includes a temperature sensor cable hole 47, which is provided separately from the through hole 46 for the heating wire 41. The temperature sensor cable hole 47 is provided such that a cable extending from the temperature sensor 42 can extend through the inner sleeve 44 in a manner similar to the heating wire 41, but not in the same hole.

[0069] Now referring Figure 4 , a three-dimensional cross-sectional view of a portion of the heat flux cone penetrometer system 1 according to an embodiment of the present invention is shown. This section illustrates the heat flux module 4 of the heat flux cone penetrometer system 1. The heat flux module 4 of the illustrated embodiment includes an inner sleeve 44 and a dissipation sleeve 43 provided around the inner sleeve 44. The inner sleeve 44 includes a groove in which the heating wire 41 is received such that the heating wire 41 rotates around the inner sleeve 44. A plurality of temperature sensors 42 are provided in slots provided on the outer surface of the inner sleeve.

[0070] The heat flux cone penetrometer system 1 includes an electronic control unit 5 provided in the heat flux module 4. In the illustrated embodiment, a single electronic control unit 5 is provided in a single heat flux module 4. Similar heat flux modules 4 may also include an electronic control unit 5. Alternatively, one electronic control unit 5 can be used to control a plurality of heat flux modules 4.

[0071] Two insulating rings 6 are provided on both sides of the heat flux module 4 such that the insulating rings 6 support the dissipation sleeve 43 and the inner sleeve 44. The insulating rings 6 are provided such that they reduce the internal heat flux in the axial and radial directions of the heat flux cone penetrometer system 1, thereby improving the quality of data acquisition.

[0072] The present invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms known to those skilled in the art.

[0073] Without departing from the spirit and scope of the present invention, further modifications to the structures and techniques described herein may be made in addition to those described above. Accordingly, although specific embodiments have been described, these are merely examples and do not limit the scope of the present invention.

Claims

1. A heat flux penetrometer system (1) for measuring the underground thermal conductivity, the heat flux penetrometer system comprising: A penetrometer (2) extending between a tip (21) and a proximal end (22); A push rod (3) arranged to transfer a compressive force to the penetrometer (2) and having a connecting section (31); And At least one heat flux module (4) provided between the proximal end (22) of the penetrometer (2) and the connecting section (31) of the push rod (3), Wherein the at least one heat flux module (4) comprises at least one heating element (41) and at least one temperature sensor (42), and Wherein the at least one heat flux module (4) comprises a dissipation sleeve (43) and an inner sleeve (44), the dissipation sleeve (43) being provided around the inner sleeve (44), and wherein the inner sleeve (44) comprises the heating element (41).

2. The heat flux penetrometer system (1) according to claim 1, comprising at least two heat flux modules (4), each heat flux module comprising at least one heating element (41) and at least one temperature sensor (42).

3. The heat flux penetrometer system (1) according to any one of the preceding claims, wherein, The at least one heat flux module (4) defines the distance to the penetrometer tip (21) between approximately 10 cm and 1 m.

4. The heat flux penetrometer system (1) according to any one of the preceding claims, comprising at least two heat flux modules (4), and wherein, The inner sleeves (44) are spaced apart in the axial direction extending along the push rod (3) and the penetrometer (2), wherein the midpoints of the first inner sleeve (44) and the second inner sleeve (44) are approximately 10 cm to 50 cm apart.

5. The heat flux penetrometer system (1) according to any one of the preceding claims, wherein, The inner sleeve (44) comprises aluminum, and wherein the dissipation sleeve (43) comprises stainless steel.

6. The heat flow penetrometer system (1) according to any one of the preceding claims, wherein, The at least one heating element (41) comprises a heating wire provided on the outer surface of the inner sleeve (44).

7. The heat flux penetrometer system (1) according to any one of the preceding claims, wherein, The inner sleeve (44) comprises at least one slot (45) for receiving the temperature sensor (42).

8. The heat flux penetrometer system (1) according to any one of the preceding claims, wherein, The inner sleeve (44) comprises at least one hole (46) arranged such that the heating wire and / or data wire of the temperature sensor (42) can extend through the hole (46).

9. The heat flux penetrometer system (1) according to any one of the preceding claims, further comprising at least one electronic control unit (5) arranged to control the temperature sensor (42) and / or the heating element (41).

10. The heat flux penetrometer system (1) according to any one of the preceding claims, wherein, The heat flux module (4) comprises at least one insulating ring (6) provided at the distal end of the heat flux module (4).

11. A heat flux module (4) for use in a heat flux penetrometer system (1) according to any one of claims 1 to 10, Among them, The inner sleeve (44) comprises the at least one temperature sensor (42).

12. A method of manufacturing a heat flux penetrometer system (1), comprising the steps of: Providing a penetrometer (2); Providing a push rod (3); Providing at least one heat flux module (4); Attach the at least one heat flux module (4) between the penetrometer (2) and the push rod (3) to form a heat flux penetrometer system (1) according to any one of claims 1 to 10.

13. A method for determining the underground thermal conductivity, comprising the steps of: Providing a heat flux penetrometer system (1) according to any one of claims 1 to 10; Advancing the heat flux penetrometer into the target soil; Heating the heat flux module (4) by supplying power to a heating element (41) of the heat flux module (4); When the heat flux module (4) is heated by the heating element (41) and / or cooled by the surrounding target soil, using a temperature sensor (42) of the heat flux module (4) to measure the temperature of the heat flux module (4) to determine a temperature gradient as a function of time.

14. A kit for producing and using parts of a heat flux penetrometer system (1), comprising: A penetrometer (2); A push rod (3); And At least one heat flux module (4) according to any one of claims 11.

Images