A distributed soil thermal conductivity test system and its test method

A technology of thermal conductivity and testing method, which is applied in the field of distributed soil thermal conductivity testing method and its testing system, can solve the problem that it is difficult to meet the calculation requirements of thermal conductivity, the acquisition of distributed thermal conductivity has not been proposed, and it is difficult to meet the hot wire method Assume conditions and other issues to achieve good contact relationship, high test efficiency, and improve test efficiency

CN111624227BActive Publication Date: 2021-07-30NANJING UNIV +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2021-07-30

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Abstract

The invention discloses a distributed soil thermal conductivity testing method and a testing system thereof. The testing method includes the following steps: embedding a composite optical cable in the soil to be tested, the composite optical cable including an optical fiber and a thermal fiber covering the optical fiber. Resistive material layer; use the heating control module to heat the soil to be tested through the thermal resistance material layer, use the optical signal processing control module to continuously collect the heating temperature data of the formation; use the optical signal processing control module to process the heating temperature data According to the thermal conductivity calculation formula, the thermal conductivity of different depths of the soil to be tested is calculated and output, and the curve of thermal conductivity and depth is drawn; the test system of the present invention is small in size, easy to carry, long in testing distance, and can monitor rocks in a deeper range. The temperature change of the soil, the test efficiency is high, the error of the test result is small, and the refined thermal conductivity of the formation can be obtained in a short test time.
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Description

technical field

[0001] The invention relates to the technical field of geological detection, in particular to a distributed soil thermal conductivity test method and a test system thereof. Background technique

[0002] The thermal conductivity of rock and soil is a key parameter reflecting the thermal conductivity of rock and soil. On the one hand, obtaining thermal conductivity can serve shallow geothermal energy evaluation, underground engineering, freezing construction or foundation design in freeze-thaw areas, etc. On the other hand, it can also indirectly calculate soil moisture content, groundwater seepage, pollutant transfer, etc. through thermal conductivity parameter.

[0003] Methods for obtaining thermal conductivity include indoor experiments and field tests. The indoor test includes the plate method and the hot wire method, and the field test is the transient hot wire method. For the transient hot wire method, a metal wire (hot wire) is inserted into the rock...

Examples

Embodiment 1

[0077] Take a specific embodiment as an example below to illustrate the specific implementation process and test effect of the present invention, and the installation of the test system is referred to figure 1 .

[0078] Step S1, burying the composite optical cable 1 in the soil body 6 to be tested;

[0079] The composite optical cable 1 is respectively connected with the optical signal processing control module 2 and the heating control module 3 to form an optical path and a heating circuit, and the connectivity of the optical path and the heating circuit is tested respectively.

[0080] Step S20, using the optical signal processing control module to collect the initial temperature of the soil to be measured, the collection interval is 0.5min, and the collection time t1≥30min; determine the standard deviation σ of the initial temperature, if the standard deviation σ>0.5 °C, repeat the step S20; if the standard deviation σ≤0.5 °C, store the initial temperature, and execute st...

Embodiment 2

[0096] like Figure 5-6 As shown, take the vertical test embodiment in a specific borehole as an example to illustrate the specific implementation process and test effect of the present invention. The depth of drilling is 95m, and the radius of the borehole is 153mm. The borehole is backfilled with fine sand, and the coupling time is longer than 6 months.

[0097] Step S1, burying the composite optical cable 1 in the soil body 6 to be tested by drilling, the composite optical cable 1 is arranged in a U shape on the wall of the transduction tube 5, which includes a sinking section 11 and a section opposite to the sinking section. The return section 12, the interval between the sinking section and the return section is 3-5cm, and the heating power q per unit length is twice the heating power per unit length of a single composite optical cable. The inner diameter of the transducer tube is 30mm, and the outer diameter is 32mm. It is arranged in the center of the borehole in a dou...