阅读说明：本技术 一种饱和砂土渗透率–导热指数测试装置及其测量方法 (Saturated sandy soil permeability-heat conductivity index testing device and measuring method thereof ) 是由 梁旭 曹锃 王立忠 邓禹 于 2021-07-16 设计创作，主要内容包括：本发明属于海洋岩土工程领域,具体涉及一种饱和砂土渗透率–导热指数测试装置及其测量方法,包括测温部和下埋部,所述下埋部上配合设置恒温热源,所述测温部上设置第一温度传感器、第二温度传感器、第三温度传感器、第四温度传感器和第五温度传感器。本发明利用恒温热源在砂土体内形成稳定分布的热场,利用温度传感器确定温度分布,基于不同渗透率–导热指数中热场分布的差异,通过砂土体渗透率,导热系数,空隙率,温度之间的关系,得到砂土体的渗透率–导热指数,适用于海底饱和砂土的渗透率–导热指数的现场原位测量,测量方法简单,效果极佳。(The invention belongs to the field of ocean geotechnical engineering, and particularly relates to a saturated sandy soil permeability-heat conductivity index testing device and a measuring method thereof. The invention utilizes the constant temperature heat source to form a stably distributed thermal field in the sandy soil body, utilizes the temperature sensor to determine the temperature distribution, obtains the permeability-heat conductivity index of the sandy soil body based on the difference of thermal field distribution in different permeability-heat conductivity indexes and through the relation among the permeability, the heat conductivity coefficient, the void fraction and the temperature of the sandy soil body, is suitable for the field in-situ measurement of the permeability-heat conductivity index of the seabed saturated sandy soil, and has simple measurement method and excellent effect.)

1. The utility model provides a saturated sand permeability-heat conduction index testing arrangement, its characterized in that includes temperature measurement portion and the lower portion of burying that the cooperation is connected from top to bottom, bury portion and temperature measurement portion down and be used for inserting the sand body, bury the cooperation in the portion down and set up the constant temperature heat source, set up first temperature sensor, second temperature sensor, third temperature sensor, fourth temperature sensor and fifth temperature sensor in the temperature measurement portion, third temperature sensor is located central authorities, fourth temperature sensor and first temperature sensor are located the upper and lower both sides of third temperature sensor respectively, fifth temperature sensor and second temperature sensor are located the left and right sides of third temperature sensor respectively.

2. The saturated sand permeability-thermal conductivity index testing device of claim 1, wherein the lower embedded part is of a conical structure.

3. The saturated sandy soil permeability-thermal conductivity index testing device as claimed in claim 1, wherein the upper end of the temperature measuring portion is connected with a supporting portion in a matching manner, and the supporting portion is used for abutting against the surface of sandy soil.

4. The saturated sandy soil permeability-thermal conductivity index testing device according to claim 3, wherein the temperature measuring portion and the supporting portion are connected with an upper connecting portion in a matched manner.

5. The saturated sandy soil permeability-heat conductivity index testing device according to claim 1, characterized in that the testing device further comprises a heat source voltage stabilization controller, a temperature display recorder, a control unit and a post-processing program module, wherein the control unit is respectively electrically connected with the heat source voltage stabilization controller, the temperature display recorder and the post-processing program module, the heat source voltage stabilization controller is electrically connected with a constant temperature heat source, and the temperature display recorder is electrically connected with the first temperature sensor, the second temperature sensor, the third temperature sensor, the fourth temperature sensor and the fifth temperature sensor.

6. A measuring method of a test apparatus according to any one of claims 1 to 5, characterized by comprising the steps of:

the method comprises the following steps: vertically inserting the lower buried part and the temperature measuring part into a sand body;

step two: connecting a temperature display recorder with a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor and a fifth temperature sensor, and displaying and recording the initial temperature of the sand body; connecting a heat source voltage stabilizing controller with a constant-temperature heat source, starting the heat source voltage stabilizing controller to heat the constant-temperature heat source, determining that the temperature value of the constant-temperature heat source is stable and unchanged through the heat source voltage stabilizing controller, determining that the temperature data of a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor and a fifth temperature sensor on a temperature display recorder are stable, and terminating the measurement;

step three: the data is imported into a post-processing program module, and the post-processing program module calculates the permeability-heat conductivity index through the following formula

In the formula: kappa-sandy body permeability; n-sandy soil porosity; viscosity coefficient of mu-water,x₁、x₂-the distance between the fifth temperature sensor and the third temperature sensor and the distance between the third temperature sensor and the second temperature sensor, respectively, in the horizontal direction; y is₁,y₂-the distance of the fourth temperature sensor from the third temperature sensor and the distance of the third temperature sensor from the first temperature sensor, respectively, in the vertical direction; rho_f-density of water; coefficient of thermal expansion of beta-water; lambda-thermal conductivity; t is_c-ambient temperature; t is₁-a temperature value determined from a temperature value measured by the first temperature sensor; t is₂-a temperature value determined from the temperature values measured by the second temperature sensor; t is₃-a temperature value determined by a temperature value measured by a third temperature sensor; t is₄-a temperature value determined by a temperature value measured by the fourth temperature sensor; t is₅-a temperature value determined from the temperature values measured by the fifth temperature sensor; c. C_pf-the heat capacity of water.

7. The method according to claim 6, wherein in the first step, the lower buried part and the temperature measuring part are driven into the sand body by a hydraulic device.

Technical Field

The invention belongs to the field of marine geotechnical engineering, and particularly relates to a saturated sandy soil permeability-heat conductivity index testing device and a measuring method thereof.

Background

The characteristics of the saturated porous medium, including the permeability and the heat conductivity coefficient, play an important guiding role in the installation and operation of ocean engineering. It was investigated that the maximum temperature decay of the submarine cable embedded in a high permeability medium (10-9m2) was more than 50% higher than the core maximum temperature decay of the submarine cable embedded in a low permeability porous medium (10-18m 2). Meanwhile, the heat conductivity coefficient of the medium plays an important role in heat dissipation of the submarine cable. In the field of rock permeability measurement research, a normal head method, a variable head method and a well hole water injection test method are commonly applied at present, wherein the normal head method and the variable head method are commonly used laboratory measurement methods, and the well hole water injection test method is a field in-situ measurement method. However, these two types of measurement methods have certain drawbacks: (1) the two methods can not directly measure the permeability of the saturated soil body in principle; (2) the laboratory measurement method destroys the objective environment of the soil body, including pressure and temperature conditions; (3) the laboratory measuring method has certain difficulty in obtaining the permeability of sandy soil in a large range; (4) the well water injection test method can obtain more accurate permeability, but the cost required by the test is higher. The measurement method mainly adopted for the thermal conductivity coefficient at present is a laboratory measurement method. Therefore, the accurate permeability and thermal conductivity of rock and soil should be determined by in-situ measurement.

Disclosure of Invention

In order to make up the defects of the prior art, the invention provides the technical scheme of the saturated sandy soil permeability-heat conductivity index testing device and the measuring method thereof, which are used for field in-situ measurement of the permeability-heat conductivity index of the seabed saturated sandy soil, reflect the permeability and heat conductivity characteristics of a sandy soil body in a measuring range and provide guidance for engineering.

The saturated sand permeability-heat conduction index testing device is characterized by comprising a temperature measuring part and a lower embedding part which are connected in an up-down matching mode, wherein the lower embedding part and the temperature measuring part are used for inserting a sand body, a constant temperature heat source is arranged on the lower embedding part in a matching mode, a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor and a fifth temperature sensor are arranged on the temperature measuring part, the third temperature sensor is located at the center, the fourth temperature sensor and the first temperature sensor are located on the upper side and the lower side of the third temperature sensor respectively, and the fifth temperature sensor and the second temperature sensor are located on the left side and the right side of the third temperature sensor respectively.

The saturated sandy soil permeability-heat conductivity index testing device is characterized in that the lower embedded part is of a conical structure.

The saturated sandy soil permeability-heat conductivity index testing device is characterized in that the upper end of the temperature measuring part is connected with a supporting part in a matching mode, and the supporting part is used for abutting against the surface of a sandy soil body.

The saturated sandy soil permeability-heat conductivity index testing device is characterized in that the temperature measuring part and the supporting part are connected with the upper connecting part in a matching mode.

The saturated sandy soil permeability-heat conductivity index testing device is characterized by further comprising a heat source voltage stabilization controller, a temperature display recorder, a control unit and a post-processing program module, wherein the control unit is electrically connected with the heat source voltage stabilization controller, the temperature display recorder and the post-processing program module respectively, the heat source voltage stabilization controller is electrically connected with a constant temperature heat source, and the temperature display recorder is electrically connected with a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor and a fifth temperature sensor.

A measuring method of the test apparatus as described above, characterized by comprising the steps of:

the method comprises the following steps: vertically inserting the lower buried part and the temperature measuring part into a sand body;

step two: connecting a temperature display recorder with a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor and a fifth temperature sensor, and displaying and recording the initial temperature of the sand body; connecting a heat source voltage stabilizing controller with a constant-temperature heat source, starting the heat source voltage stabilizing controller to heat the constant-temperature heat source, determining that the temperature value of the constant-temperature heat source is stable and unchanged through the heat source voltage stabilizing controller, determining that the temperature data of a first temperature sensor, a second temperature sensor, a third temperature sensor, a fourth temperature sensor and a fifth temperature sensor on a temperature display recorder are stable, and terminating the measurement;

step three: the data is imported into a post-processing program module, and the post-processing program module calculates the permeability-heat conductivity index through the following formula

In the formula: kappa-sandy body permeability; n-sandy soil porosity; mu-viscosity coefficient of water, x₁、x₂-the distance between the fifth temperature sensor and the third temperature sensor and the distance between the third temperature sensor and the second temperature sensor, respectively, in the horizontal direction; y is₁,y₂-the distance of the fourth temperature sensor from the third temperature sensor and the distance of the third temperature sensor from the first temperature sensor, respectively, in the vertical direction; rho_f-density of water; coefficient of thermal expansion of beta-water; lambda-thermal conductivity; t is_c-ambient temperature; t is₁-a temperature value determined from a temperature value measured by the first temperature sensor; t is₂-a temperature value determined from the temperature values measured by the second temperature sensor; t is₃-a temperature value determined by a temperature value measured by a third temperature sensor; t is₄-a temperature value determined by a temperature value measured by the fourth temperature sensor; t is₅-a temperature value determined from the temperature values measured by the fifth temperature sensor; c. C_pf-the heat capacity of water.

The measuring method is characterized in that in the first step, the lower embedded part and the temperature measuring part are driven into a sand body through a hydraulic device.

Compared with the prior art, the method has the advantages that the constant-temperature heat source is utilized to form the thermal field which is stably distributed in the sandy soil body, the temperature distribution is determined by utilizing the temperature sensor, the permeability-heat conductivity index of the sandy soil body is obtained through the relation among the permeability, the heat conductivity coefficient, the void ratio and the temperature of the sandy soil body on the basis of the difference of the thermal field distribution in different permeability-heat conductivity indexes, the method is suitable for the field in-situ measurement of the permeability-heat conductivity index of the seabed saturated sandy soil, the measurement method is simple, and the effect is excellent.

Drawings

FIG. 1 is a schematic structural diagram of a testing apparatus according to the present invention;

FIG. 2 is a schematic diagram of a circuit relationship of the testing device of the present invention;

FIG. 3 is a flow chart of the measurement method of the present invention.

Detailed Description

In the description of the present invention, it is to be understood that the terms "one end", "the other end", "outside", "upper", "inside", "horizontal", "coaxial", "central", "end", "length", "outer end", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention.

The invention utilizes a constant temperature heat source to form a stably distributed thermal field in the sandy soil body, and obtains the permeability-thermal conductivity index of the sandy soil body through the relation among the permeability, the thermal conductivity coefficient, the void ratio and the temperature of the sandy soil body based on the difference of thermal field distribution in different permeability-thermal conductivity indexes. The method can be used for the field in-situ measurement of the saturated sand soil permeability-heat conductivity index in geotechnical engineering, and reflects the permeability and heat conductivity characteristics of the saturated sand soil.

The invention will be further explained with reference to the drawings.

Referring to fig. 1 and 2, a saturated sand permeability-thermal conductivity index testing device includes a temperature measuring portion 17 and a lower embedded portion 2 which are connected in a vertical matching manner, the lower embedded part 2 and the temperature measuring part 17 are used for being inserted into a sand body 1, the constant temperature heat source 3 is arranged on the lower embedded part 2 in a matching way, the constant temperature heat source 3 provides a stable heating body to form a stable temperature field of a test area, the temperature measuring part 17 is made of phenolic resin materials, a first temperature sensor 6, a second temperature sensor 7, a third temperature sensor 8, a fourth temperature sensor 9 and a fifth temperature sensor 10 are arranged on the upper part in a penetrating way, the third temperature sensor 8 is positioned in the center, the fourth temperature sensor 9 and the first temperature sensor 6 are respectively positioned at the upper side and the lower side of the third temperature sensor 8, the fifth temperature sensor 10 and the second temperature sensor 7 are respectively positioned at the left and right sides of the third temperature sensor 8. The five temperature sensors are used for measuring the temperature of a test area, and particularly a PT100 platinum resistance temperature sensor of the tin-free mass sensor technology limited company is selected.

With continued reference to fig. 1, the lower buried portion 2 has a tapered structure, so that the lower buried portion 2 can be inserted into the sand body 1 to reduce the disturbance of the sand body 1.

With reference to fig. 1, the middle of the temperature measuring part 17 is in a triangular structure, so that the overall rigidity of the temperature measuring part 17 can be enhanced, and the disturbance to the sandy soil body 1 in the process of entering the soil can be reduced.

Continuing to refer to fig. 1, the upper end of the temperature measuring portion 17 is connected to the upper connecting portion 11 in a matching manner, the upper end of the upper connecting portion 11 is connected to the supporting portion 12 in a matching manner, and the supporting portion 12 is of a flat plate structure and is made of stainless steel material and used for abutting against the surface of the sandy soil body 1.

In addition, the testing device further comprises a heat source voltage stabilizing controller 14, a temperature display recorder 15, a control unit 18 and a post-processing program module 16, wherein the control unit 18 is respectively electrically connected with the heat source voltage stabilizing controller 14, the temperature display recorder 15 and the post-processing program module 16, the heat source voltage stabilizing controller 14 is electrically connected with the constant temperature heat source 3, and the temperature display recorder 15 is electrically connected with the first temperature sensor 6, the second temperature sensor 7, the third temperature sensor 8, the fourth temperature sensor 9 and the fifth temperature sensor 10. The heat source voltage-stabilizing controller 14 is used for controlling a sensor on the constant-temperature heat source 3 to display voltage-stabilizing control heating, and specifically selects an AI-719 type precision artificial intelligence heat source voltage-stabilizing controller of Xiamen electric automation technology Limited. The temperature display recorder 15 is used for recording the temperature of a test area in real time, and specifically adopts an NHR-8716 color temperature display recorder of Shandong rainbow automation instrument Co. The post-processing program module 16 is used for analyzing the temperature data obtained by the temperature display recorder 15.

Referring to fig. 3, a measurement method of the test apparatus described above includes the following steps:

the method comprises the following steps: the hydraulic device vertically inserts the lower embedded part 2 and the temperature measuring part 17 into the sandy soil body 1, and the supporting part 12 is abutted against the surface of the sandy soil body 1 so as to limit the insertion depth of the lower embedded part 2 and the temperature measuring part 17;

step two: connecting a temperature display recorder 15 with a first temperature sensor 6, a second temperature sensor 7, a third temperature sensor 8, a fourth temperature sensor 9 and a fifth temperature sensor 10, and displaying and recording the initial temperature of the sand body 1; connecting a heat source voltage stabilizing controller 14 with a constant-temperature heat source 3, starting the heat source voltage stabilizing controller 14 to heat the constant-temperature heat source 3, determining that the temperature value of the constant-temperature heat source 3 is stable and unchanged through the heat source voltage stabilizing controller 14, determining that the temperature data of a first temperature sensor 6, a second temperature sensor 7, a third temperature sensor 8, a fourth temperature sensor 9 and a fifth temperature sensor 10 on a temperature display recorder 15 are stable, and terminating measurement;

step three: the data is imported into the post-processing program module 16, and the post-processing program module 16 calculates the permeability-thermal conductivity index by the following formula

In the formula: k-sand body permeability, m²(ii) a n-sandy soil porosity; μ -viscosity coefficient of water, pas; x is the number of₁、x₂The spacing, m, of the fifth temperature sensor 10 from the third temperature sensor 8 and of the third temperature sensor 8 from the second temperature sensor 7, respectively, in the horizontal direction; y is₁,y₂The spacing in the vertical direction of the fourth temperature sensor 9 from the third temperature sensor 8 and the spacing in the vertical direction of the third temperature sensor 8 from the first temperature sensor 6, m, respectively; rho_fDensity of water, kg/m³(ii) a Coefficient of thermal expansion of beta-water, 1/deg.C; lambda-thermal conductivity, W/(m.deg.C); t is_c-ambient temperature, ° c; t is₁A temperature value, deg.c, determined from the temperature values measured by the first temperature sensor 6; t is₂A temperature value, deg.c, determined from the temperature values measured by the second temperature sensor 7; t is₃A temperature value, deg.c, determined from the temperature values measured by the third temperature sensor 8; t is₄Temperature determined by the temperature value measured by the fourth temperature sensor 9Value, ° c; t is₅A temperature value, deg.c, determined from the temperature values measured by the fifth temperature sensor 10; c. C_pfThe heat capacity of water, J/kg.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.