CN105607130A - Method for detecting hole peripheral karst or cavity by using drilling and high-density electrical method - Google Patents

Abstract

The invention relates to a method for detecting hole peripheral karst or cavities by using a drilling and high-density electrical method. The method provided by the invention aims to effectively avoid the condition that a ground high-density electrical method is liable to be restricted by surface covered layer interface and deep detection precision degradation, accurately detect karst or cavities with different depth on the periphery of a drill hole, and effectively solve the problem of ''a narrow view'' of a drilling exploration method. The method is characterized in that a hole is drilled in a target region and filled with water, a high-density electrical method test cable is placed in the drill hole, the cable is a sealed waterproof cable, and the cable is provided with copper core electrodes arranged at equidistance; and one end of the high-density electrical method test cable extends into the bottom part of the drill hole, the other end is exposed out of the drill hole and is connected with a high-density electrical method main machine, a four-electrode symmetric Wenner device mode is utilized, and high-density electrical method data acquisition of the entire hole section is completed automatically. The method is applicable to detect the karst and underground cavities on the periphery of the drill hole.

Description

A kind of method that detects all karst in hole or cavity with boring high-density electric

Technical field

The present invention relates to a kind of method that detects all karst in hole or cavity with boring high-density electric. Be applicable to inspectionSurvey karst and underground cavity that boring exists around.

Background technology

Karst is in many-sided engineering geologic investigations such as work China Democratic National Construction Association, highway, Railway Environment, usually can meetSituation about arriving. Due to corrosion make can lava surface clint, lapies grow thickly, uneven; Underground karst cavityDestroy again Rock Mass Integrality. The variation of karst water dynamic condition, make its top overlying soil produce cracking,Depression. Underground karst usually shows with the form on solution cavity, underground gallery, underground underground river, and these are notWith degree affect the stability of structure foundation.

In karst and coal mine gob, underground karst and goaf belong to Serious geological disasters, will be seriousThe safety that threatens engineering, causes great harm to underground engineerings such as track traffics, especially before engineering constructionThe distribution of finding out karst developmental state and goaf with the construction stage is extremely important. At present, Underground karstWith the method in goaf mainly contain probing method and GPR method, (ground) high-density electric, auspicious Rayleigh Wave Method,The geophysical prospecting method such as electromagnetic wave CT method between elastic wave CT method, hole between transient electromagnetic method, hole, but probing method is " oneThe opinion in hole ", can not find often " to edge away karst or the cavity of borehole circumference "; GPR method, (Face) method such as high-density electric, auspicious Rayleigh Wave Method, transient electromagnetic method is in the investigation depth that has a cover layer area veryLimited, and it is very easily subject to environmental disturbances, for multiple stack karst or more indistinguishable of cavity; Bullet between holeProperty ripple CT and electromagnetic wave CT method at least need two borings, and can only detect in two borings and connectKarst on line or cavity, easily " wipe line and cross ", cannot find out karst or the sky in other orientation of borehole circumferenceHole.

Wherein, high-density electric is a kind of effectively engineering geophysical method. The method is to send out from conventional resistivity methodExhibition, its operation principle is also substantially identical with conventional resistivity method. It is taking the electrical property difference of Rock And Soil asBasis. Apply under electric field action the regularity of distribution of conductive electric current in underground Rock And Soil according to it, infer undergroundWith the distribution situation of the geologic body of resistivity. In fact high-density electric measures underground various Rock And SoilResistivity. Because measured resistivity value is to record there is multiple Rock And Soil in the situation that underground, soBe not the true resistivity of a certain rock, it is except being subject to the combined influence of various rock resistivities, also with rock,The concrete condition such as distribution (comprising-a little structural factors), electrode arrangement of ore is relevant, so claim it to beApparent resistivity. Determine apparent resistivity size because have: the 1. true resistivity of each rock stratum geologic body; 2. undergroundDifferent electrically body actual distribution situations (thickness of each electrical body, size and shape, the depth of burying); 3. supplyThe mutual alignment of electricity electrode and measurement electrode and with the relative position of inhomogeneous electrical layer.

At present, all there is more deficiency in the effect of existing various detection karst or empty method, at ringBorder is disturbed in complicated city underground engineering and more to be lacked reliable, effective method.

Summary of the invention

The technical problem to be solved in the present invention is: for above-mentioned existing problems, provide a kind of by boring high densityElectrical method detects hole week karst or the method in cavity, and effectively evading ground high-density electric, to be subject to earth's surface cover layer dryDisturb the restriction deteriorated with deep detection accuracy, can accurately detect karst or the cavity of borehole circumference different depth,Effectively solve probing method " a peephole view ".

The technical solution adopted in the present invention is: a kind of with all karst in boring high-density electric detection hole or cavityMethod, it is characterized in that: in object region boring, and fill water, in boring, put into high-density electricTest cable, this cable is water-tight cable, on it with the equidistant copper core electrode of arranging; Described highly denseDegree electrical method test cable one end stretch to foot of hole, the other end expose boring and with high-density electric main frame phaseConnect, utilize four extremely symmetrical winners that device patterns, automatically complete the data collecting way by high density electrical of full hole section;

Utilize inversion interpretation software to process the data of collection, form boring resistivity chromatogram,According to the low-resistance characteristic of the high resistant characteristic of cavity or karst, judge the rock in certain limit in borehole circumference country rockMolten or empty growth, and place depth location, form and size.

The aperture of described boring is 56mm～90mm, more than hole depth exceedes plan detection degree of depth 5m.

The electrode spacing of described high-density electric test cable is:

In formula: d---electrode spacing; D---drilling depth; The number of electrodes of N---test cable.

The position in borehole circumference karst or cavity is determined in the boring that adopts several intersections to be drilled with.

The invention has the beneficial effects as follows: the method that the present invention adopts is according to Rock Resistivity and karst or cavityThe principle there are differences between resistivity designs, and detects in boring; Utilize high-density electric instrumentDevice automatically gathers the apparent resistivity of each electrode spacing and carries out inverting matching imaging analysis, forms centered by boringCylindrical resistivity image, by analyzing the resistivity contrasts of karst or cavity and borehole circumference country rock, looks intoGrow in karst in bright borehole circumference certain limit or cavity, has expanded the investigative range of boring; The present invention hasEffect has been evaded ground high-density electric and has been subject to earth's surface cover layer interference and the deteriorated restriction of deep detection accuracy, canAccurately to detect karst or the cavity of borehole circumference different depth, efficiently solve " a peephole view " of probing method.

Brief description of the drawings

Fig. 1 is four extremely symmetrical winners that device ideographs in the present invention.

Fig. 2 is the high-density electric testing arrangement figure that holes in the present invention.

Fig. 3 is the high-density electric inverting resistivity chromatogram of holing in the present invention.

Detailed description of the invention

As Figure 1-3, operation principle of the present invention is: cavity has high resistant characteristic, and that karst has is lowResistance characteristic, there is larger difference with borehole circumference shoulder-bed resistivity (SBR), in resistivity imaging figure, be high resistant orLow resistance abnormity area, can judge thus whether borehole circumference exists karst or cavity, and be speculated as karst or cavity.Specifically, according to (ground) high-density electric principle, the cable repacking rear defence water power on ground will be laid in originallyAfter cable, put into boring 1, use the rod-shaped electrode of being driven underground instead copper core electrode 2-1, copper core electrode is generalHave 60, electrode spacing is d; Using the water of holing in 1 as couplant, utilize high-density electric instrument automaticGather the apparent resistivity of each electrode spacing and carry out inverting matching imaging analysis, form cylinder centered by boringResistivity image, by analyzing karst or cavity and the resistivity contrasts of 1 peripheral rock of holing, find out brillThe growth in the karst in the 1 periphery certain limit of hole or cavity, expands the investigative range of holing; But list only holes 1Testing result cannot judge that this karst or cavity, in the position of orientation of borehole circumference, can utilize three to only reach above brillIts position is determined in hole intersection.

The present embodiment is a kind of method that detects borehole circumference karst or cavity with boring high-density electric, firstIn 3 borings 1 that are drilled with of precalculated position intersection, the aperture of boring 1 is about 56mm～90mm, in hole, fillsWater, hole depth exceed intend detect the degree of depth be no less than 5m, by high-density electric test cable 2 (through repacking waterproofCable and copper core electrode 2-1) put into boring, at the bottom of one end to hole, the other end expose boring and with high density electricityMethod main frame 4 (as DUK-2 high-density electric instrument) is connected, the extremely symmetrical winners that of employing four device patterns (asFig. 1), automatically complete the data collecting way by high density electrical (as Fig. 2) of full hole section.

The data of collection in worksite are used inversion interpretation software (as Sweden Res2dinv high-density electric inversion interpretationSoftware) process, (chromatogram represents with color to obtain high-density electric inverting resistivity chromatogramThe height of resistivity, as red 5 expression high resistants, blue 6 represent low-resistances). As shown in Figure 3, in chromatogramBetween position show blue region be low-resistance region, analyze the karst into the low-resistance such as filling water or mud object.

In the present embodiment, each electrode of high-density electric test cable 2 connects high-density electric by cable and adoptsCollecting system, adopts four extremely equidistant symmetrical winner device acquisition modes, automatically gathers the potential difference of different interpolar distanceAnd supply current.

According to electrical prospecting principle, as follows completely without the apparent resistivity ρ computing formula of limit space medium in boring:

$\mathrm{\ρ}=\frac{4\mathrm{\π}}{I}\frac{V}{(\frac{1}{AM}-\frac{1}{MB}-\frac{1}{AN}+\frac{1}{NB})}=K\frac{V}{I}$

In formula: ρ_s---apparent resistivity; V---the potential difference between measurement electrode; The electricity of I---current supply circuitIntensity of flow; K---electrode coefficient, relevant with measurement electrode spacing with power supply.

The theoretical value that each pole span actual measurement apparent resistivity and forward modeling are calculated compares, and utilizes young waiter in a wineshop or an innAn object function of multiplication structure:

$\mathrm{\φ}=\left|\right|\mathrm{\Δ}d-A\mathrm{\Δ}m|{|}_2^2$

In formula: Δ d---the residual error vector of actual measurement apparent resistivity and model theory of computation value; Δ m---model ginsengThe correction vector of number; A---partial derivative matrix.

Make object function obtain minimum of a value by continuous correction model parameter, now revised model is situated between exactlyThe geoelectric parameter of matter, namely resistivity figure. At present, the high density electricity based on least squares theoryMethod inverting the Fitting Calculation method is more, and current commercial high-density electric inversion interpretation software is very universal, itsMiddle Sweden Res2dinv high-density electric inversion interpretation software is exactly one of them.

The boring resistivity figure being obtained by inversion interpretation, according to the high resistant characteristic of cavity or the low-resistance of karstCharacteristic, can judge whether boring exists karst or cavity in 1 peripheral rock, and place depth location, shapeState and size. Method of discrimination is as follows:

In boring 1 rock section, if having high resistant or low-resistance region in borehole resistivity picture, this figure place is darkIn the basement rock of degree position, have karst or cavity, high resistant is cavity, and low-resistance is water or mud filling; High resistant or lowThe resistance edge in district and the distance of boring are karst or cavity and the distance of holing, high resistance area or low-resistance region greatlyLittle karst or the empty section size of being substantially equal to, but single testing result of only holing cannot be judged this karst or skyHole is in the position of orientation of borehole circumference, can utilize three to only reach above boring intersection and determine its position.

The electrode spacing of high-density electric test cable 2 and cable length carry out according to drilling depth and radius of investigationRegulate, borehole circumference effective detection range (radius of investigation) is relevant with test cable length, is generally cable1/6～1/10 of length. This test cable electrode spacing is calculated as follows:

$d=\frac{D}{N-1}$

In formula: d---electrode spacing; D---drilling depth; The number of electrodes of N---test cable is generalBe 60.

Claims (4)

1. a method that detects all karst in hole or cavity with boring high-density electric, is characterized in that: at orderRegion boring (1), and fill water, in boring (1), put into high-density electric test cable (2), shouldCable is water-tight cable, on it with the equidistant copper core electrode (2-1) of arranging; Described high-density electricTest cable (2) one end stretches to foot of hole, the other end expose boring and with high-density electric main frame (4)Be connected, utilize four extremely symmetrical winners that device patterns, automatically complete the high-density electric data acquisition of full hole sectionCollection;

Utilize inversion interpretation software to process the data of collection, form boring resistivity chromatogram,According to the low-resistance characteristic of the high resistant characteristic of cavity or karst, in judgement boring (1) peripheral rock in certain limitKarst or cavity grow, and place depth location, form and size.

2. according to claim 1ly a kind ofly detect hole week karst or cavity with boring high-density electricMethod, is characterized in that: the aperture of described boring (1) is 56mm～90mm, and hole depth exceedes to be intended detecting deeplyMore than degree 5m.

3. according to claim 1 and 2 a kind of with all karst in boring high-density electric detection hole or cavityMethod, it is characterized in that: the electrode spacing of described high-density electric test cable (2) is:

$d=\frac{D}{N-1}$

In formula: d---electrode spacing; D---drilling depth; The number of electrodes of N---test cable.

4. a kind of side of detecting all karst in hole or cavity with boring high-density electric according to claim 1Method, is characterized in that: adopt the boring (1) that several intersections are drilled with to determine borehole circumference karst or cavityPosition.