CN102953363A - Resistivity detector for quantitatively evaluating change of soil porosity - Google Patents

Resistivity detector for quantitatively evaluating change of soil porosity Download PDF

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Publication number
CN102953363A
CN102953363A CN2012104572231A CN201210457223A CN102953363A CN 102953363 A CN102953363 A CN 102953363A CN 2012104572231 A CN2012104572231 A CN 2012104572231A CN 201210457223 A CN201210457223 A CN 201210457223A CN 102953363 A CN102953363 A CN 102953363A
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probe
soil body
soil
resistivity
stainless steel
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蔡国军
刘松玉
张涛
邹海峰
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Southeast University
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Southeast University
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Abstract

The invention discloses a resistivity detector for quantitatively evaluating the change of soil porosity; at the upper half part of a probe of the detector, an insulated polyvinyl chloride (PVC) material (1) and a stainless steel circular electrode (2) form a resistance sensor; in the structure, the insulated PVC material (1) and the stainless steel circular electrode (2) are lined at the upper half part of the probe at intervals from top to down in sequence; the lower half part of the probe is provided with a side wall friction tube (3); a pore water pressure sensor (4) is arranged in the middle of the side wall friction tube (3); a conical probe (5) is connected below the side wall friction tube (3); and a pore pressure filter ring (6) is arranged between the side wall friction tube (3) and the conical probe (5). The detector has the characteristics of original position, quickness, accuracy, economy and the like, and a powerful detection tool is provided for the practice of the soil disturbance evaluation in a model test and the foundation treatment in civil engineering.

Description

The resistivity probe that a kind of quantitative assessment soil body porosity changes
Technical field
The present invention relates to a kind of resistivity probe, belong to a kind of in the geotechnical engineering field can be continuously, the static sounding device of test beds original position porosity change quantitatively.
Background technology
The static sounding technology refers to utilize the pressure apparatus will be with the sounding rod indentation test soil layer of contact probe, the static point resistance of throughput examining system test soil, side friction power etc., can determine some basic physical mechanics properties of soil, such as the modulus of deformation of soil, the allowable bearing of soil etc.The static sounding technology is the history in existing more than 80 year so far.The extensive use static sounding has partly or entirely replaced probing and the sampling in the engineering investigation in the world.China at first succeeded in developing the electric measuring type static sounding and is applied to prospecting in nineteen sixty-five.Along with the fast development of sensor technology, a lot of new static sounding technology occurred in recent years, these technology can obtain pore water pressure, seismic wave, pollutant proterties, temperature even the image of soil layer quickly and accurately.The method of at present quantitative assessment soil body porosity change mainly contains optical method and resistance method.Common optical method measuring technology comprises stereo measurement technology, digital imaging technology, transparent native experimental technique, X ray test technology and other image processing techniques.Except X ray test and transparent native technology, optical method is only applicable in the transparent model-container in border, and this has just limited the measurement of failure mode.The resistance method generally has two kinds of heat resistance method and electric-resistivity methods.Although electric-resistivity method still may hinder the soil particle failure mode, allow near the probe distortion of certain limit to occur, and use, an and soil body density linear dependency relation irrelevant with the soil particle shape, obtain more accurate soil body porosity feature.
The present invention is based on conventional static sounding probe, provide a kind of can be continuously, quantitatively, in-situ test instrument accurately and fast, processing for model testing and geotechnical engineering ground provides accurately and effectively method for quantitatively evaluating.
Summary of the invention
Technical problem: the technical problem to be solved in the present invention is the in situ quantitation evaluation that can't soil body porosity changes for domestic, but proposes the resistivity probe that a kind of quantitative assessment soil body porosity that can be used for the geotechnical engineering field changes.Utilize this probe effectively quantitative assessment be subjected to the porosity of disturbed soil to change size.
Technical scheme: the first half of the resistivity probe that quantitative assessment soil body porosity of the present invention changes adopts insulation PVC material and stainless steel annular electrode to form electric resistance sensor; Structurally the first half of this probe sequentially is provided with insulation PVC material and stainless steel annular electrode from top to down alternately; The Lower Half of probe is provided with the sidewall friction cylinder, is provided with pore water pressure sensor in the middle of the sidewall friction cylinder, is connected with the circular cone probe below the sidewall friction cylinder, is provided with hole press filtration ring between sidewall friction cylinder and circular cone probe.
Hole press filtration ring thickness is 5mm, sidewall friction cylinder surface area 150cm 2
The cone angle of circular cone probe is 60 °, and the cone basal cross section is long-pending to be 10cm 2, not waiting the end area ratio is 0.8.
The quantity of stainless steel annular electrode is 4, and thickness is 1.5mm, and width is 5mm, and arrangement pitches is 10mm, and the total length that is distributed in probe is 50mm.
Circuits System and four electrodes by probe inside measure middle two interelectrode voltage change synchronously, continuously, and calculate the resistivity size of electrode surrounding soil according to Ohm's law principle factorization.According to Ohm's law, the resistivity probe is surveyed the soil in-situ electricalresistivityρ and is:
ρ = AV IL
In the formula, A is by being surveyed soil body cross-sectional area (m 2), L is soil body length (m), V be internal power source voltage (v); I is electric current (A).
Because geometrical property A, the L of the test soil body are difficult to determine, obtain the theoretical equation of soil body resistance R according to Ohm's law:
R = V I
Soil body porosity change amount △ n can be expressed as:
△n=c[(R soil;i-R soil;0)-(R ref;i-R ref;0)]
In the formula, c is index of correlation, can concern that by resistivity and porosity linear correlation indoor standardization is definite, R Soil; i, R Ref; iBe respectively i soil body resistance and reference resistance (Ω) constantly, R Soil; 0, R Ref; 0Be respectively soil body resistance and the reference resistance (Ω) of initial time.
Beneficial effect: on-the-spot ground is processed or indoor model test all can to original soil body generation disturbance in various degree, affect the effect of ground processing and the accuracy of model testing directly or indirectly.The method that at present continuous and quantitative evaluation soil body porosity changes adopts optical method usually.Yet optical method is only applicable to laboratory test and having relatively high expectations to test, such as the transparent model-container in border, the image processing techniques etc. of specialty may hinder the measurement of the failure mechanism of soil particle simultaneously in the test process, the shortcoming such as cause the experimental result reliability to reduce, experimentation cost is higher.
The invention solves the defective that domestic existing optical method measuring technology can not detect soil disturbance process mesopore rate variable quantity better, continuously, exactly, the change of quantitative assessment soil body porosity that can be continuous, accurate and effective.So that the resistivity probe can more fully be served the geotechnical engineering field.This technology has the characteristics of continuity, quantitative and reliability.
Description of drawings
Fig. 1 is component arrangement figure of the present invention;
Wherein have: insulation PVC material 1, stainless steel annular electrode 2, sidewall friction cylinder 3, pore water pressure sensor 4, circular cone probe 5, hole press filtration ring 6.
The specific embodiment
The first half of the resistivity detector probe that quantitative assessment soil body porosity of the present invention changes adopts insulation PVC material 1 and stainless steel annular electrode 2 to form electric resistance sensor; Structurally the first half of this probe sequentially is provided with insulation PVC material 1 and stainless steel annular electrode 2 from top to down alternately; The Lower Half of probe is provided with sidewall friction cylinder 3, is provided with pore water pressure sensor 4 in the middle of the sidewall friction cylinder 3, is connected with circular cone probe 5 below sidewall friction cylinder 3, is provided with hole press filtration ring 6 between sidewall friction cylinder 3 and circular cone probe 5.
Be illustrated in figure 1 as the schematic diagram of measurement.Described stainless steel annular electrode 2 is 50mm at the total length of probe vertical direction.
The thickness of described four stainless steels annular electrode 2 is 1.5mm, and width is 5mm, and spacing is 10mm.
Because the contact conditions between electrode conductor and the soil body is comparatively complicated, for simplicity, suppose that the soil body all equates with contact resistance between conductor electrode.Voltage under the constant current between middle two conductor electrodes of test is reduced to V s, and the low passage strainer of the Bessel (Besse1) of test value by 40Hz filtered, in order to reduce the interference of different frequency power supply etc.Calculate the resistance R of the soil body according to Ohm's law Soil, the resistance R of the test soil body SoilCan be expressed as:
R soil = V s R ref V c
In the formula, V cBe supply voltage (v), R RefReference resistance (Ω) for probe.
Sensor type, insulation materials and fringe conditions etc. different so that the contact resistance between electrode conductor and the soil body becomes very complicated, obtain the linear representation of soil body porosity change Δ n by Ohm's law and model testing:
△n=c[(R soil;i-R soil;0)-(R ref;i-R ref;0)]
In the formula, c is index of correlation, can concern that by resistivity and porosity linear correlation indoor standardization is definite, R Soil; i, R Ref; iBe respectively i soil body resistance and reference resistance (Ω) constantly, R Soil; 0, R Ref; 0Be respectively soil body resistance and the reference resistance (Ω) of initial time.

Claims (4)

1. the resistivity probe that quantitative assessment soil body porosity changes is characterized in that the first half of this detector probe adopts insulation PVC material (1) and stainless steel annular electrode (2) to form electric resistance sensor; Structurally the first half of this probe sequentially is provided with insulation PVC material (1) and stainless steel annular electrode (2) from top to down alternately; The Lower Half of probe is provided with sidewall friction cylinder (3), be provided with pore water pressure sensor (4) in the middle of the sidewall friction cylinder (3), be connected with circular cone probe (5) in the below of sidewall friction cylinder (3), between sidewall friction cylinder (3) and circular cone probe (5), be provided with hole press filtration ring (6).
2. the resistivity probe of quantitative assessment soil body porosity change according to claim 1 is characterized in that hole press filtration ring (6) thickness is 5mm, sidewall friction cylinder (3) surface area 150cm 2
3. the resistivity probe of quantitative assessment soil body porosity change according to claim 1 is characterized in that the cone angle of circular cone probe (5) is 60 °, and the cone basal cross section is long-pending to be 10cm 2, not waiting the end area ratio is 0.8.
4. the resistivity probe that changes of quantitative assessment soil body porosity according to claim 1, the quantity that it is characterized in that stainless steel annular electrode (2) is 4, and thickness is 1.5mm, and width is 5mm, arrangement pitches is 10mm, and the total length that is distributed in probe is 50mm.
CN2012104572231A 2012-11-14 2012-11-14 Resistivity detector for quantitatively evaluating change of soil porosity Pending CN102953363A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103343530A (en) * 2013-06-21 2013-10-09 东南大学 Micro-scale pore pressure static sounding probe for effectively identifying extra-thin soil layer
CN108444883A (en) * 2018-03-14 2018-08-24 河南科技大学 Subsoiling vapour-pressure type porosity detection device
CN109030945A (en) * 2018-06-08 2018-12-18 同济大学 A kind of soil resistivity sensing device based on high-density electric observation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01111914A (en) * 1987-10-21 1989-04-28 Kiso Jiban Consultants Kk Method and apparatus for static cone penetration test
JP2005331288A (en) * 2004-05-18 2005-12-02 Nippon Chiken Kk Display method of soil constitution based on cone penetration test
CN201635064U (en) * 2010-04-12 2010-11-17 东南大学 Resistivity static sounding probe

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01111914A (en) * 1987-10-21 1989-04-28 Kiso Jiban Consultants Kk Method and apparatus for static cone penetration test
JP2005331288A (en) * 2004-05-18 2005-12-02 Nippon Chiken Kk Display method of soil constitution based on cone penetration test
CN201635064U (en) * 2010-04-12 2010-11-17 东南大学 Resistivity static sounding probe

Non-Patent Citations (4)

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Title
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103343530A (en) * 2013-06-21 2013-10-09 东南大学 Micro-scale pore pressure static sounding probe for effectively identifying extra-thin soil layer
CN103343530B (en) * 2013-06-21 2015-08-26 东南大学 The micro-scale pores pressure static sounding probe of the very thin soil layer of a kind of effective identification
CN108444883A (en) * 2018-03-14 2018-08-24 河南科技大学 Subsoiling vapour-pressure type porosity detection device
CN109030945A (en) * 2018-06-08 2018-12-18 同济大学 A kind of soil resistivity sensing device based on high-density electric observation

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Application publication date: 20130306