CN2622713Y - A.C. low frequency soil resistivity tester - Google Patents

Abstract

An A.C. low frequency soil resistivity tester tests the soil resistivity, which can be applied in civil engineering field. The A.C. low frequency soil resistivity tester consists of a signal collecting circuit and a signal processing circuit. The signal collecting circuit comprises a brachium pontis selecting circuit 1 and the signal processing circuit comprises a frequency selecting circuit 2, a signal indicating circuit 3, a close-loop circuit 4 and a resistance selecting circuit 5. The tested resistance R x is respectively connected with the resistance selecting circuit, the closed-loop circuit, the signal indicating circuit and the brachium pontis selecting circuit. One end of the brachium pontis selecting circuit is connected with the resistance selecting circuit and the other end is connected with the closed-loop circuit, the frequency selecting circuit is connected with the signal indicating circuit. The brachium pontis selecting circuit consists of two rows of resistances. One end of the brachium pontis selecting circuit is connected with the tested resistance, the voltmeter A of the signal indicating circuit and the voltmeter B of the closed-loop circuit. The other end of the brachium pontis selecting circuit is connected with one end of the series resistance of the resistance selecting circuit. Complete electric bridge is produced by two rows of resistances comprising the tested circuit, the resistance signal circuit and the brachium pontis selecting circuit.

Description

Exchange low frequency soil resistivity tester

One, technical field

The utility model is a kind of field of civil engineering that is applicable to, to the device that the electrical resistivity property of soil is tested, belongs to the technical field of native testing apparatus.

Two, background technology

The structure of soil is the principal element of decision soil body engineering mechanics property, this structural engineering properties to soil has strong influence, thereby soil carried out the quantitative examination of micromechanism, the quantitative description of seeking the structural change of soil in deformation process has become one of focus target of current geotechnical study.Because the complicacy of rock soil medium micromechanism form and the limitation of technological means, also there are some problems in existing soil structure research method commonly used: (1) microstructure study sample preparation difficulty, test trouble; (2) variability is big, and the different researchers of same soil sample tend to draw different conclusions, even adopt image analysis technology, because the difference that sample is selected also is difficult to draw consistent conclusion; (3) can not Continuous Observation; (4) some measuring technologies as soil layer CT cost height, are used inconvenience; (5) some technology are for diminishing test.

The resistivity of soil is the basic parameter that characterizes native electric conductivity, is one of intrinsic physical parameter of soil.In recent years, many foreign scholars connect the aspect each other to electrical resistivity property and microstructural parameter, macromechanics characterisitic parameter and have carried out many research work, make great efforts simultaneously to explore feasibility and the validity that it is applied to the structure Quantitative study of soil, and obtained many useful achievements.And existing resistivity measurement system generally adopts the direct current electrical measurement.This electrical measurement can be described some non-conductive particles pore texture characteristics such as (sand, rubbles); In the system that the spheroidal particle of conduction constitutes, resin suspending liquid for example, if concentration of electrolyte is high, its structure and geometrical property are assessed in also available direct current electrical measurement; In more complicated system, direct current electrical measurement poor effect is for example arranged in the clay systems of different-grain diameter, shape, directionality and character of surface.What also need in addition to carry is to cause moving electric coupling phenomenon-electric osmose and electrochemical effect under the DC electric field effect, thereby causes system's generation irreversible change.Adopt alternating current then can reduce to minimum.Thereby the test soil structure in the structural change process quantitatively changes, and should adopt the interchange electrical measurement.

Selection about a-c cycle, studies show that: but the electrical response feature effecting reaction soil particle size in low frequency district, the architectural characteristics such as level of disruption of size distribution, grain orientation, the electrolytical kind of hole liquid and concentration, particle surface feature and sample, frequency is high or cross low all unsuitable [2].The frequency height, anti-interference is poor, and the data instability is difficult to effectively disclose native architectural characteristic; Underfrequency, electric signal is not obvious, and sensitivity is not high.And existing interchange electric pilot is generally the high-frequency ac electric bridge and frequency only is the DZ-1 type low-frequency resistance rate instrument of 5hz.

Three, summary of the invention

1, technical matters

In order to solve the resistivity measurement problem of existing field of civil engineering soil, goal of the invention of the present utility model provides a kind of interchange low frequency soil resistivity tester that is applicable to field of civil engineering, fundamentally change the difficulty in traditional soil structure research and the application, improve the operability and the consistance of soil structure index greatly, and will for on-the-spot original position structure index determine lay the foundation.

Two, technical scheme

Interchange low frequency soil resistivity tester of the present utility model, formed by signal acquisition circuit, signal processing circuit, it is characterized in that signal acquisition circuit comprises that brachium pontis selection circuit, signal processing circuit comprise frequency selective network, signal indicating circuit, zero-detection circuit, resistance selection circuit, measured resistance selects circuit, zero-detection circuit, signal indicating circuit, brachium pontis to select circuit to join with resistance respectively; Brachium pontis selects a terminating resistor of circuit to select circuit, another termination zero-detection circuit, and frequency selective network and signal indicating circuit join.

Brachium pontis selects circuit to be made up of two row's resistance, voltage table A in one termination measured resistance and the signal indicating circuit, the voltage table B in the zero-detection circuit, other end connecting resistance is selected an end of the resistance in series in the circuit, selects circuit, brachium pontis to select two row's resistance in the circuit to form complete electric bridge by measured resistance, resistance.The resistance of resistance is respectively 20 Ω, 40 Ω, 60 Ω, 80 Ω, 100 Ω, 150 Ω, 200 Ω, 400 Ω, 600 Ω, 800 Ω, 1000 Ω in every row's resistance in the brachium pontis selection circuit.Resistance is selected in the circuit, become by 4 adjustable resistance string joint groups, the Standard resistance range of first resistance is 0.1 Ω～1 Ω, and the Standard resistance range of second resistance is 1 Ω～10 Ω, the Standard resistance range of the 3rd resistance is 10 Ω～100 Ω, and the Standard resistance range of the 4th resistance is 100 Ω～1000 Ω.

According to the electrical model of soil,, measure the resistance R of soil by regulating the balance of low frequency alternating current bridge _x, and then obtain the electrical resistivity property index of soil and architectural characteristic index-F, f, A.

$R_{\mathrm{xV}}=R_v\frac{R_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y0322240100081.png"\; state="\{\{state\}\}">R</figure-callout>}}_2};$ $R_{\mathrm{xH}}=R_H\frac{R_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="Y0322240100081.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}$

${\mathrm{\&rho;}}_v=\frac{R_v{S}_v}{L_v};$ ${\mathrm{\&rho;}}_H=\frac{R_H{S}_H}{L_H}$

F _v＝ρ _v/ρ _w；F _H＝ρ _H/ρ _w

$\stackrel{\&OverBar;}{F}=\frac{F_v+{2F}_H}{3};$ $A=\sqrt{\frac{F_V}{F_H}};$ By F=n ^-fObtain f.

R in the formula _XV, R _XHFor vertical, the level of soil to resistance; ρ _v, ρ _HFor vertical, the level of soil to resistivity; ρ _wBe pore water resistivity; R _V, R _HBe adjustable resistance; R1, R2 are measuring resistance; F is the average inner structure factor of soil; F _V, F _HFor vertical, the level of soil to structure factor; N is a porosity; F is an average shape factor; A is an anisotropic index; S _V, S _HBe vertical, the level of surveying soil electrode slice area to resistance; L _V, L _HFor surveying vertical, the distance of level between the electrode slice of resistance of soil.

The course of work of low-frequency ac electric bridge measuring resistance

(1) connects measured resistance, select " arm resistance " close with measured resistance; Height according to measured resistance is selected suitable " signal intensity ".

(2) turn on the power switch, regulate " resistance selection " each grade knob, the value of " zero-detection indication " is pointed to till the minimum, " resistance selection " each grade sum is the value of measured resistance at this moment.

Six, beneficial effect

The utility model can AC/DC, is convenient to indoor, on-the-spot test; Frequency is from the continuous stepping of 20～100hz, and is adjustable; Voltage amplitude is adjustable continuously, and can decay; Galvanometer, voltage all numeral show.Solved the resistivity measurement problem of existing field of civil engineering soil, be applicable to the interchange low frequency soil resistivity measurement of field of civil engineering, fundamentally change the difficulty in traditional soil structure research and the application, improve the operability and the consistance of soil structure index greatly, and will for on-the-spot original position structure index determine lay the foundation.

Four, description of drawings

Fig. 1 is a schematic block circuit diagram of the present utility model.Wherein have brachium pontis select circuit 1, frequency selective network 2,

Signal indicating circuit 3, zero-detection circuit 4, resistance are selected circuit 5, measured resistance Rx.

Fig. 2 is circuit theory diagrams of the present utility model.

Fig. 3 is 3 1/2 digital display A.C. voltmeter electrical schematic diagrams.

Five, embodiment

Interchange low frequency soil resistivity tester of the present utility model, formed by signal acquisition circuit, signal processing circuit, signal acquisition circuit comprises that brachium pontis selection circuit 1, signal processing circuit comprise frequency selective network 2, signal indicating circuit 3, zero-detection circuit 4, resistance selection circuit 5, and measured resistance Rx selects circuit 5, zero-detection circuit 4, signal indicating circuit 3, brachium pontis to select circuit 1 to join with resistance respectively; Brachium pontis selects a terminating resistor of circuit 1 to select circuit 5, another termination zero-detection circuit 4, and frequency selective network 2 joins with signal indicating circuit 3.Brachium pontis selects circuit 1 to be made up of two row's resistance, voltage table A in one termination measured resistance Rx and the signal indicating circuit 3, the voltage table B in the zero-detection circuit 4, other end connecting resistance is selected an end of the resistance in series in the circuit 5, selects circuit 5, brachium pontis to select two row's resistance in the circuit 1 to form complete electric bridge by measured resistance Rx, resistance.The resistance of resistance is respectively 20 Ω, 40 Ω, 60 Ω, 80 Ω, 100 Ω, 150 Ω, 200 Ω, 400 Ω, 600 Ω, 800 Ω, 1000 Ω in every row's resistance in the brachium pontis selection circuit 1.Resistance is selected in the circuit 5, become by 4 adjustable resistance string joint groups, the Standard resistance range of first resistance is 0.1 Ω～1 Ω, and the Standard resistance range of second resistance is 1 Ω～10 Ω, the Standard resistance range of the 3rd resistance is 10 Ω～100 Ω, and the Standard resistance range of the 4th resistance is 100 Ω～1000 Ω.Resistance in the frequency selective network 2 is respectively 20 Ω, 30 Ω, 40 Ω, 50 Ω, 60 Ω, 70 Ω, 80 Ω, 90 Ω, 100 Ω.

Soil sample is contacted with the electrode slice of customization, after putting into the insulation vessel of customization, when carrying out conventional geotechnique's compression, expansion, triaxial test, with its resistance of pacing, can obtain the Changing Pattern of soil in these processes according to the course of work of low-frequency ac electric bridge measuring resistance.

Claims (5)

1, a kind of interchange low frequency soil resistivity tester, formed by signal acquisition circuit, signal processing circuit, it is characterized in that signal acquisition circuit comprises that brachium pontis selection circuit (1), signal processing circuit comprise frequency selective network (2), signal indicating circuit (3), zero-detection circuit (4), resistance selection circuit (5), measured resistance (Rx) selects circuit (5), zero-detection circuit (4), signal indicating circuit (3), brachium pontis to select circuit (1) to join with resistance respectively; Brachium pontis selects a terminating resistor of circuit (1) to select circuit (5), another termination zero-detection circuit (4), and frequency selective network (2) joins with signal indicating circuit (3).

2, interchange low frequency soil resistivity tester according to claim 1, it is characterized in that brachium pontis selection circuit (1) is made up of two row's resistance, voltage table A in one termination measured resistance (Rx) and the signal indicating circuit (3), the voltage table B in the zero-detection circuit (4), other end connecting resistance is selected an end of the resistance in series in the circuit (5), selects circuit (5), brachium pontis to select two row's resistance in the circuit (1) to form complete electric bridge by measured resistance (Rx), resistance.

3, interchange low frequency soil resistivity tester according to claim 1 and 2 is characterized in that the resistance of resistance in the every row's resistance in the brachium pontis selection circuit (1) is respectively 20 Ω, 40 Ω, 60 Ω, 80 Ω, 100 Ω, 150 Ω, 200 Ω, 400 Ω, 600 Ω, 800 Ω, 1000 Ω.

4, interchange low frequency soil resistivity tester according to claim 1 and 2, it is characterized in that in the resistance selection circuit (5), become by 4 adjustable resistance string joint groups, the Standard resistance range of first resistance is 0.1 Ω～1 Ω, the Standard resistance range of second resistance is 1 Ω～10 Ω, the Standard resistance range of the 3rd resistance is 10 Ω～100 Ω, and the Standard resistance range of the 4th resistance is 100 Ω～1000 Ω.

5, interchange low frequency soil resistivity tester according to claim 1 and 2 is characterized in that the resistance in the frequency selective network (2) is respectively 20 Ω, 30 Ω, 40 Ω, 50 Ω, 60 Ω, 70 Ω, 80 Ω, 90 Ω, 100 Ω.

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