EP1662225A1 - Probe for measuring stretch in a borehole - Google Patents

Abstract

The probe has retaining units (17a, 17b, 20a, 20b) brought in contact with a measuring tube and a displacement transducer detecting an opposite space of the retaining units. An evaluation unit evaluates obtained measured values. The units are adjusted perpendicular to longitudinal direction of the probe and radial to the tube and are stretched radially outward against an inner wall of the tube under the effect of springs (18, 21).

Description

The invention relates to a borehole distance measuring probe for insertion into a measuring tube, which is introduced into a borehole or attached to a building and at predetermined intervals defined measuring marks, with an upper probe head and a lower probe head, which are mounted variable in their mutual distance and each having holding elements, which are engageable at the measuring marks with the measuring tube, with at least one displacement sensor, by means of which the mutual distance of the holding elements can be detected, and with an evaluation device by means of which the recorded measured values can be evaluated.

In many geotechnical areas it is necessary and useful to monitor the movements of the ground, a building or a mountain. It may be the monitoring of structures, such as a tunnel or a dam, or to the detection and monitoring of potential Landslides or to study the source behavior of a mountain act.

For the geotechnical deformation measurement so-called borehole distance measuring probes are known which are retracted at regular time intervals in a measuring tube which is arranged in a borehole or attached to a building. The measuring tube has, at predetermined axial distances of, for example, one meter precisely defined measuring marks whose mutual distance is measured and recorded by means of the borehole distance measuring probe.

In the following, it should be assumed by way of example that the borehole runs substantially vertically and the borehole distance measuring probe is inserted from above into the likewise vertical measuring tube. The terms "top" and "bottom" used in this specification refer to this embodiment.

The borehole track probe has an upper probe head and a lower probe head which are adjustable in their mutual distance. By means of a measuring device in the form of one or more transducers, the mutual distance of the probe heads can be determined exactly.

The measuring tube is composed of a plurality of individual, preferably similar measuring tube parts, each having a relatively small length of about one meter and are connected to each other via pipe sleeves. In the region of each pipe sleeve, a measuring mark is formed in the form of a plurality of radially inwardly pointing projections, which are distributed discontinuously over the circumference, so that passages are formed between the projections.

The probe heads each have radially outwardly projecting holding elements, which are also distributed discontinuously over the circumference. Depending on the rotational position of the probe head, the holding elements can either pass the measuring mark at the passages or engage under the projections of the measuring mark in a form-fitting manner.

In order to carry out a measurement, the borehole distance measuring probe is lowered down to a desired depth into the measuring tube on a linkage, wherein the probe heads pass the measuring marks at their passages. Subsequently, a rotational force is applied via the linkage to the borehole distance measuring probe and thus to its probe heads, whereby they are pivoted by a predetermined angle, for example 45 °, so that the holding elements of the probe heads are arranged below the projections of the measuring marks. Then the borehole distance measuring probe is raised until the holding elements of the lower probe head from below come into contact with the projections of the associated measuring mark. Upon further lifting of the downhole probe, the upper probe head will move relative to the lower probe head until its support members engage the protrusions of the associated gauge from below. Thus, the measuring position is reached, in which the distance between the two probe heads is detected by means of the displacement transducer and the evaluation unit is supplied. A comparison of the measured values obtained with the measured values from an earlier measurement at exactly the same measuring marks gives information on whether the measuring marks have shifted in the meantime.

After completion of the described measurement, the borehole distance measuring probe is pivoted back by means of the linkage, so that the holding elements can pass through the passages of the measuring mark, and then by the length of a Lifted measuring tube part, whereupon a similar measurement is performed on the two other consecutive measurement marks. This procedure is repeated until the measuring tube is measured in a predetermined section and in particular over its entire length.

The implementation of a measurement with a borehole distance measuring probe of the type mentioned is very laborious and time consuming. Even the lowering of the borehole-length measuring probe into the measuring tube takes a relatively long time, since it requires a linkage with which the borehole distance measuring probe a torque or a rotational force can be applied to rotate the probe heads in the manner mentioned. The assembly of a corresponding linkage of individual linkage parts takes a relatively long time and the handling of the borehole distance measuring probe is thereby considerably more difficult. In addition, the borehole track probe must always have a predetermined rotational orientation in the meter tube in order to lower or raise it in the meter tube. This is technically unfavorable.

The invention has for its object to provide a borehole distance measuring probe of the type mentioned, with which the measuring tube can be measured in a simple and cost-effective manner.

This object is achieved with a borehole-length measuring probe with the characterizing features of claim 1. It is provided that the holding elements are adjustable perpendicular to the longitudinal direction of the borehole distance measuring probe and radially to the measuring tube adjustable and under the action of a spring radially outward against the inner wall of the measuring tube.

According to the invention, the basic idea is to not engage the probe heads with the measuring tube in a form-fitting manner at the measuring points, but instead to position the probe heads at the measuring points by a spring force, ie. to reach frictionally. The holding elements are tensioned by means of spring force outwards against the inner wall of the measuring tube and can engage there undercuts or measuring stops formed at the measuring points, as long as the holding force determined by the spring force is not overcome by a larger pull-off force. The essential advantage of this embodiment is that the probe heads need not assume a predetermined rotational or pivotal position in the measuring tube for their positioning at the measuring points, so that it is possible to dispense with the use of a torsionally rigid rod. Instead, the borehole distance measuring probe can be lowered into the measuring tube, for example, on a cable or cable and pulled up in it. In this way, on the one hand the device-technical effort is much lower and also the implementation of the measurement of the measuring tube can be achieved in a much shorter time. In addition, a forced centering of the borehole distance measuring probe within the measuring tube is ensured by the radial adjustability of the holding elements and their resilient mounting, which is particularly useful for carrying out further measurements with the probe, such as inclination measurements within the measuring tube.

To carry out a measurement, the borehole distance measuring probe is lowered, for example, on a cable or cable under its own weight in the measuring tube until the probe heads are each arranged below those measuring marks whose distance is to be measured below. Subsequently the borehole distance measuring probe is raised slowly and carefully in the measuring tube. When the spring-loaded holding elements of the lower probe head reach the assigned measuring mark, they engage in the undercuts or depressions formed there. The spring force of the holding elements of the lower probe head is dimensioned so that the engagement with the measuring mark of the measuring tube is maintained when the borehole distance measuring probe is further raised in the following. In this case, a relative movement between the upper and the lower probe head occurs until the spring-loaded holding elements of the upper probe head strike or engage in the undercuts or recesses of the associated measuring mark. In this state, the measuring position is reached and the detected by the displacement transducer relative movement between the two probe heads is given to the evaluation in which the mutual distance of the measuring marks and its comparison can be done with previous measurements.

In order to disengage the holding elements of the probe heads from their engagement with the measuring marks, the borehole distance measuring probe is either pulled jerkily upwards, so that the holding force of the holding elements is overcome by the dynamic effects of this pulling movement. Alternatively, it is also possible to first lower the borehole distance measuring probe as a result of its own weight by a small amount in the measuring tube and then to pull it upwards relatively quickly with increased tensile force, so that the dynamic effects occurring prevent the probe heads from becoming blocked Holding elements can set at the associated measuring points.

Preferably, each probe head has a plurality of retaining elements distributed over the circumference of the borehole distance measuring probe.

In one possible embodiment of the invention, it is provided that each probe head has at least two essentially diametrally opposed holding elements.

In principle, it is possible that each retaining element has its own spring, with which it is stretched radially outward against the inner wall of the measuring tube. Preferably, however, it is provided that each probe head has only one corresponding spring, so that the holding elements of each probe head are under the action of a common spring.

The spring forces, with which the holding elements of the upper probe head and the lower probe head are clamped radially against the inner wall of the measuring tube, can be the same size. In a preferred embodiment of the invention, however, it is provided that the force acting on the holding elements of the lower probe head spring force F _{U is} less than the force acting on the holding elements of the upper probe head spring force F _o . It has proven useful if the ratio V of the two spring forces (V = F _O / F _U ) in the range of 1.1 to 2.0 and in particular in the range of 1.2 to 1.6. Due to the increased design of the upper spring force F _O on the one hand ensures that additional unscheduled dynamic loads that are introduced when using the borehole distance measuring probe by the user via the cable or cable in the upper part of the borehole distance measuring probe in this can be reliably absorbed and do not cause the retaining elements to pop out of their support at the measuring points. In addition, due to the increased upper spring force Fo, it is possible to pull the borehole length measuring probe with sufficient force against the stops of the upper measuring point, after previously the holding elements of the lower probe head are already engaged at the lower measuring point, without There is a risk that the upper probe head will be pulled beyond the upper measuring point.

The radially adjustable mounting of the holding elements is preferably achieved in that each holding element has a toggle lever formed by two articulated linkage parts and an engagement member mounted thereon. The toggle lever or the two linkage parts form a joint triangle pointing radially outward with the tip, on the outer hinge point of which the engagement part is arranged, which is preferably a roller which can roll on the inner wall of the measuring tube. The two radially inner base hinge points of the toggle lever are adjustable relative to one another in the longitudinal direction of the measuring tube, resulting in a radial mobility of the outer hinge point and thus the engagement part. Preferably, one of the inboard base hinge points is fixedly attached to the downhole probe, while the other base hinge point is under the action of a spring biasing it towards the other base hinge point and thus the engagement member radially outwardly against the inner wall of the meter tube stressed.

The toggle lever forms a substantially lying in a vertical sectional plane of the measuring tube triangle with an upper and a lower linkage part. Preferably, the two linkage parts have a different length and are arranged at different angles relative to the longitudinal axis of the borehole distance measuring probe and thus of the measuring tube. Due to the geometric configuration and arrangement of the toggle lever, different spring forces to be overcome for lowering and pulling up the borehole distance measuring probe in the measuring tube can be achieved. In a preferred embodiment of the invention is provided that the lengths of the linkage parts and / or the angles are in a mutual ratio of about 1: 2.

The longer linkage member, which is at a shallower angle relative to the longitudinal axis of the wellbore track probe than the shorter linkage member, is disposed on the side facing the bottom of the wellbore track probe. In this way, it is ensured that when lowering or lowering the borehole distance measuring probe in the measuring tube due to the present leverage ratios, only relatively small spring forces of the holding elements are to be overcome, while raising or raising the borehole distance measuring probe due to the upper, relatively steep employee , Short linkage parts are to overcome greater spring forces of the holding elements.

The borehole track probe may be conventionally equipped with tilt sensors for vertical and / or horizontal tilt measurement. Furthermore, a temperature sensor can be arranged in the borehole distance measuring probe in order to be able to take into account temperature influences on the mutual distance of the measuring points in the evaluation of the measurement results. Additionally or alternatively, a measuring tube torsion can be detected by the lower probe head is rotatably mounted with its holding elements relative to the upper probe head in a range of ± 5 °. For detecting the measuring tube torsion and a measuring tube inclination, it is necessary for the holding elements of the probe heads to assume a predetermined position in the circumferential direction of the measuring tube, which can be achieved, for example, by providing at least one linear tube extending over the length of the measuring tube Groove is formed.

Fig. 1

einen ausschnittweisen Vertikalschnitt durch ein Messrohr,

Fig. 2

das untere Ende des Messrohres mit eingefahrener Bohrloch-Streckenmesssonde,

Fig. 3

eine schematische Darstellung der Kniehebel-Lagerung der Halteelemente,

Fig. 4

die Bohrloch-Streckenmesssonde zu beginn eines Messvorgangs,

Fig. 5

die Bohrloch-Streckenmesssonde gemäß Fig. 4 nach Erreichen der unteren Messmarke,

Fig. 6

die Bohrloch-Streckenmesssonde gemäß Fig. 5 nach erfassen auch der oberen Messmarke und

Fig. 7

die Bohrloch-Streckenmesssonde gemäß Fig. 6 nach Beendigung der Messung und während des Verfahrens zu weiteren Messmarken.

Further details and features of the invention will become apparent from the following description of an embodiment with reference to the drawings. Show it:

Fig. 1

a partial vertical section through a measuring tube,

Fig. 2

the lower end of the measuring tube with retracted borehole distance measuring probe,

Fig. 3

a schematic representation of the toggle bearing of the holding elements,

Fig. 4

the borehole distance measuring probe at the beginning of a measuring process,

Fig. 5

the borehole distance measuring probe according to FIG. 4 after reaching the lower measuring mark,

Fig. 6

the borehole distance measuring probe according to FIG. 5 also detect the upper measuring mark and

Fig. 7

the borehole distance measuring probe according to FIG. 6 after completion of the measurement and during the process to further measuring marks.

Fig. 1 shows the basic structure of a measuring tube 1, in which the borehole distance measuring probe according to the invention is used. The measuring tube 1 consists of a plurality of measuring tube 2, 3 and 4 arranged coaxially in series, wherein successive Meßrohrteile are each firmly connected to each other by means of an au-βenseitigen pipe sleeve 5. in the In the region of each tube sleeve 5, a lower undercut 3a or 4a is respectively formed on the measuring tube parts 2, 3 and 4, which represents a measuring mark. The measuring tube parts 2, 3 and 4 all have a relatively short, equal length of, for example, a little less than one meter, so that the lower undercuts or measuring marks 3a, 4a of successive measuring tube parts have a predetermined defined distance of preferably one meter. Fig. 2 shows the lower end of the measuring tube 1, which is closed by means of an end cap 6.

In the measuring tube 1, a borehole distance measuring probe 10 is arranged, which has an elongate, in the axial direction of the borehole distance measuring probe 10 and the measuring tube 1 extending housing 11, at the upper end of an upper probe head 19 is arranged. The upper probe head 19 has two diametrically opposed support members 20a, 20b which are substantially perpendicular to the direction of measurement, i. are adjustable to the longitudinal direction of the measuring tube 1 and under the action of an upper spring 21 are radially outwardly clamped against the inner wall of the measuring tube 1.

Above the upper probe head 19, the borehole distance measuring probe 10 is connected via a fastening 23 to a cable 22 which leads to the upper end of the measuring tube 1 at the earth's surface and over which the borehole distance measuring probe 10 in the measuring tube 1 can be lowered and raised. In addition, the cable 22 serves as a data line for the transmission of measurement data to an external evaluation device.

At the lower end of the borehole distance measuring probe 10, a lower probe head 12 is provided which basically has the same structure as the upper probe head 19 and also has two diametrically opposite holding elements 17a and 17b, which are adjustable substantially perpendicular to the measuring direction and radially to the measuring tube 1 and under the action of a lower spring 18 are radially outwardly clamped against the inner wall of the measuring tube 1.

The lower probe head 12 is connected via a running inside the housing 11 rod 13 with a transducer 14 and can be moved together with this relative to the housing 11 and thus relative to the upper probe head 19 axially, as is schematically indicated by a bellows 16 , Between the displacement transducer 14 and the housing 11, a return spring 15 is arranged, which acts on the position transducer in an initial position.

Fig. 3 shows a schematic representation of the structure of the holding elements, wherein for example the holding member 17a is shown, but the other holding elements 17b, 20a and 20b have basically the same structure.

The holding element 17a comprises a toggle lever 24, which is formed by two articulated linkage parts 25 and 26, and an engagement part 27 in the form of a roller. The two linkage parts 25 and 26 lie in a longitudinal plane extending in the longitudinal direction of the borehole distance measuring probe 10 and are held at their respective radially inner ends via a base joint 25a and 26a on the lower probe head 12 and at its radially outer hinge point 28 hinged together , Wherein also the engagement part 27 is attached to the radially outer hinge point 28. As shown in FIG. 3, the two linkage parts 25 and 26 have a different length and are oriented at different angles relative to the longitudinal axis L of the borehole distance measuring probe.

The upper, shorter linkage member 25 is held immovably to the lower probe head 12 with its inner base hinge point 25a and extends approximately at an angle of 35 ° to 45 ° relative to the longitudinal axis L.

The lower, longer linkage member 26 is guided at its inner base hinge point 26 a axially displaceable on the lower probe head 12 and biased by the lower spring 18 (see FIG. 2) in the direction of the base hinge point 25 a of the other linkage parts 25, as shown by Arrow F _{U is} indicated, which represents the force exerted by the lower spring 18 lower spring force. The lower linkage member 26 is about twice as long as the upper linkage member 25 and extends at a substantially shallow angle in the range of 15 ° to 25 ° relative to the longitudinal axis L.

As a result of the spring force F _{U of} the radially outer hinge point 28 of the toggle lever 24 to which the two rod members 25 and 26 are connected to each other and on which the roller-shaped engaging member 27 is mounted, pressed radially outward, and is thus under spring tension on the inner wall of the measuring tube 1 at.

The holding parts 20a and 20b of the upper probe head 19 mounted in the same way are also stretched radially outwards against the inner wall of the measuring tube 1 by the force F _{O of} the upper spring 21, the two spring forces F _U and F _O, however, being different. The ratio V = F _O / F _U is in the range of 1.1 and 2.0 and in particular in the range of 1.2 to 1.6. The spring force of the return spring 15 of the displacement transducer 14 substantially corresponds to the spring force F _{U of} the lower spring and is thus also lower than the spring force F _{O of} the upper spring.

The carrying out of a single measurement will be explained below with reference to FIGS. 4 to 7, with which the distance between a lower measuring mark M _u on the underside of a measuring tube part and an upper measuring mark M _{o is} to be determined on the underside of the overlying measuring tube part.

The Bohroch-Streckenmesssonde 10 is first released as a result of their own weight in the measuring tube 1 until the lower probe head 12 is located well below the lower measurement mark M _u and the upper probe head 19 well below the upper measurement mark M _o . This condition is shown in FIG.

The distance between the holding elements of the lower probe head 12 and the holding elements of the lower probe head 19 is slightly less than the lowest expected mutual distance of the measuring marks M _u and M _o . When the borehole distance measuring probe is pulled up slowly within the measuring tube by means of the cable 22, the holding elements of the lower probe head first snap into the circumferential recess near the lower measuring point M _u and undercut the undercuts or measuring stops as shown in FIG. 5 is. The holding elements of the upper probe head 19 have not yet reached the upper measuring mark M _o , as is also apparent from FIG. 5.

If a further upwardly directed tensile force is exerted on the borehole distance measuring probe 10 located in the position according to FIG. 5 by means of the cable 22, the underneath the probe head 12 remains due to the engagement of its retaining elements with the undercuts on the lower measuring mark M _u . while the upper probe head 19 is raised axially together with the housing 11 until the holding elements of the upper probe head 19 reach the upper measuring mark M _o and with the local undercuts or

Measuring stops come into contact. The relative movement between the lower probe head 12 and the upper probe head 19 also leads to a relative movement between the transducer 14 and the housing 11 under tension of the return spring 15, as shown in Fig. 6. The said relative movement can be detected by means of the displacement transducer 14, so that it is possible to ascertain exactly how far the two measuring marks M _u and M _o are from each other. The measured values are forwarded via the cable 22 to an evaluation device positioned above ground.

After the measured values have been recorded, the borehole distance measuring probe 10 is moved downwards by a short distance by releasing the cable 22 and then pulled up abruptly, whereby the two probe heads 12 and 19 receive the associated measuring mark M ₀ or M _u each happen due to the dynamic loads and thus the starting position for the measurement of the next higher measurement marks is reached, whereupon a measurement is performed in the illustrated manner.

Claims (11)

Borehole length measuring probe (10) for insertion into a measuring tube (1) which is placed in a borehole or attached to a building and at predetermined intervals defined measuring marks (3a, 4a), with an upper probe head (19) and a lower probe head (12), which are mounted variable in their mutual distance and each holding elements (17a, 17b, 20a, 20b), which at the measuring marks (3a, 4a) with the measuring tube (1) are engageable, with at least one displacement sensor (14), by means of which the mutual distance of the holding elements (17a, 17b, 20a, 20b) can be detected, and with an evaluation device by means of which the recorded measured values can be evaluated, characterized in that the holding elements (17a, 17b, 20a, 20b ) substantially perpendicular to the longitudinal direction of the borehole distance measuring probe and radially to the measuring tube (1) adjustable and under the action of a spring (18, 21) radially outwardly against the inner wall of the measuring tube (1) are tensionable. Borehole distance measuring probe according to claim 1, characterized in that each probe head (12, 19) has at least two substantially diametrically opposed holding elements (17a, 17b, 20a, 20b). Borehole distance measuring probe according to claim 1 or 2, characterized in that the holding elements (17a, 17b, 20a, 20b) of each probe head (12, 19) under the action of a common spring (18, 21). Borehole distance measuring probe according to one of claims 1 to 3, characterized in that on the holding elements (17a, 17b) of the lower probe head (12) acting spring force F _U less than that on the holding elements (20a, 20b) of the upper probe head (19 ) acting spring force F _o is. Borehole distance measuring probe according to claim 4, characterized in that a spring force ratio V = F _O / F _U in the range of 1.1 to 2.0 and in particular in the range of 1.2 to 1.6. Borehole distance measuring probe according to one of claims 1 to 5, characterized in that each holding element (17a, 17b, 20a, 20b) formed by two articulated linkage parts (25, 26) toggle lever (24) and an engagement member mounted thereon (27) having. Borehole-length measuring probe according to claim 6, characterized in that the engagement part (27) is formed by a roller. The borehole length measuring probe according to claim 6 or 7, characterized in that the linkage parts (25, 26) have different lengths and are arranged at different angles relative to the longitudinal axis L of the borehole distance measuring probe (10). Borehole distance measuring probe according to claim 8, characterized in that the lengths of the linkage parts (25, 26) are in a mutual ratio of about 1: 2. Borehole distance measuring probe according to one of claims 8 or 9, characterized in that the angles are in a mutual ratio of about 1: 2. A wellbore track probe as claimed in any one of claims 8 to 10, characterized in that the longer linkage member (26) extending at a lesser angle relative to the longitudinal axis L of the borehole track measuring probe (10) is located on the lower end of the borehole track measuring probe (10). 10) facing side is arranged.

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