DE10118083A1 - Method for testing the stability under load and flectional resistance of a post anchored in the ground at the post's base applies a unit of force to introduce a flectional load on the post and load it with moment of flexion. - Google Patents

Abstract

A unit of force introduces flectional load on a post to load the post with moment of flexion. A displacement sensor measures drift caused by the moment of flexion. Time is recorded in milliseconds in an abscissa and the drift in the post is recorded in mm. in an ordinate. Three overlaid curves are displayed. In a first area (D) drift is reduced because flectional load is generated with a hydraulic driving mechanism and pressure in a hydraulic cylinder drops off. Areas of drift (A-F) appear in three curves (1-3) for changes in flectional load.

Description

The invention relates to a method for testing the stability and bending strength of a on the mast foot anchored in the ground using a force unit with white cher introduced a bending load acting in one direction of force into the mast and there is loaded with a bending moment by the mast, and a displacement sensor for Measuring the mast deflection caused by the bending moment. Under the term "bending load" - also referred to as "test pressure" - are given in this due to the continuously increasing or decreasing loads also loads caused by the introduction of a mechanical vibration or by Understood shock.

A measuring method for checking the stability and bending strength of a mast is described in EP 0 638 794 A1. In the known, the bending load (by train and / or pressure) with the help of an excavator boom into the mast and with measured with a pressure sensor. The resulting deflection of the mast with the help of a distance sensor standing on a tripod next to the mast summarizes. In the practical implementation, the measurement results of pressure and Position sensor recorded at the same time. As a rule, it is necessary to put the mast in to load two directions that are offset at an angle of up to 90 ° to one another to be able to record symmetries of mast stability. The well-known mast test changes several successive loads each with a shift of Means for exerting (and measuring) the bending load, e.g. B. the excavator, and the means for detecting the deflection, namely the displacement sensor. Still, in the end cannot be said whether the respectively determined mast deflection is due to an error  of the mast itself or from movement of the mast in the foundation or what proportion of mast deflection on the foundation and what proportion on the above-ground part of the mast is due. Ultimately, the individual Mast in the known only checked qualitatively, meaningful numerical measurements can not be delivered.

A known measuring system is described in DE 195 40 319 C1. After that too a mast deflection caused by a bending moment is measured. If there is a risk that the effect of the bending moment will cause not just one Mast deflection but also a movement of the mast foundation is an additional way for the mast foot in the familiar directly on the ground sensor for detecting the position of the mast foundation.

It has already been proposed (DE 100 08 202.5, AT: 23.2.2000) on one Mast to provide at least two measuring points one above the other and the measurement result se from the different altitudes on a single receiver for the un unite indirect comparison. The measuring points can be equipped with light transmitters and Light receivers are equipped so that they allow the through a Bending load caused movement or deflection of one provided on the mast Register measuring position in three dimensions. Instead of the optical measuring system me can also use electrical sensors, e.g. B. potentiometers, magnetic sensors, z. B. inductors, or mechanical sensors, e.g. B. with springs, who used the. More recently, you can register the individual positions of the mast Satellite navigation receivers can also be used to measure the results Record and record two-dimensional or three-dimensional form can. Can be recorded in any coordinate system such. B. in Gauß-Krüger or in the UTM system. The distance to be recorded can in each case be registered as a change in coordinates under bending load (or alternating load).

The invention has for its object that when testing the stand and Bie strength to be exerted on the mast and its anchoring (load) To reduce stress and / or the test time compared to the prior art. With in other words, the data for the delivery of meaningful data on stability or bending strength  of a mast, the total test load required for the test required time should be kept to a minimum. Another job consists of bending the mast above the top of the earth regardless of the movement So below the top of the earth independently. H. adjusted, from the free Bo and a possible soil compaction, even with weakly anchored ones Masts to capture. The goal is to create the maximum bie to determine the strength of a mast based on the measurements, since with you can decide whether additional loads, e.g. B. streets signs to be put on.

The solution according to the invention exists for the method of the type mentioned at the beginning in that the mast deflection caused by the bending load according to the amount and if necessary, direction near the top of the earth and at a greater distance is measured from the top of the earth and that the measurement results thus acquired time be summarized point-by-point in a common diagram. Some embodiments of the invention are specified in the subclaims.

The fact that according to the invention at the same time near the top of the earth and with larger distance from the top edge is measured and the measurement results time be summarized point-by-point in a common diagram, is achieved that for testing a single mast only one in a single bending load is required in order to provide meaningful data on the To provide mast stability and anchorage. So that the measurement time and the stress on the mast is reduced. The details of this will be explained below.

According to a further invention, stress stress and measuring time during the test of a mast can be reduced even further if the bending load is not continuous but pumping with an increase following a pump pressure rise phase phase is increased, and thereby the fattening caused by an increase in pressure motion is measured. The latter measurement should also take place during the the respective recovery phase following the recovery phase. Thereby, in each pump pressure increase phase, one corresponding to the pressure increase  forced mast movement reached, on - in the recovery phase - egg ne relatively free mast return movement follows. The mast return movement in the recovery phase can be overlaid by mast vibrations.

If there is an increase in the bending load with a constant pump amplitude and Frequency sets an almost equally constant course of the mast movement (possibly with gradually increasing mast load as the test load increases per pump stroke), one can say that the mast is in order. This is especially true then when the mast movement near the top of the earth and with a larger Distance from the top of the earth is approximately in the same direction. But when significant deviations from a norm are registered, e.g. B. if the mast deflection in the course of the pumping process from pump stroke to pump stroke takes, or if movements in one another at the two measuring points of the mast other deviating directions can be determined before reaching the provided maximum load can be said that the mast is in order or he ha be a mistake (which often has to be investigated further). In the former case, the Test with a positive result (= the mast is OK) after a relatively short period of time ringem stress exerted on the mast and mostly after a relatively short measuring time be det. In the other case, before the intended maximum is reached can be determined that the mast and / or its anchoring possibly egg have a mistake. Checking the course of the mast movement in response to the Pressure rise and recovery phase - in short: fine structure of the mast movement - during a pumping increase in the bending load therefore always has an Ab shortening of the measuring method compared to the prior art to follow because the Bending load normally no longer went up to its maximum value must be ren.

In the present case, the expression “in the vicinity” means the top edge of the earth hang a distance from the floor in the order of a hand's breadth. alternative can also be taken from a measurement with a clear distance below an eventu Speak in the inspection door provided in the mast. The measurement "with larger Ab stood "above the top of the earth means a measurement in the context of the invention clearly above a possibly existing inspection door of the mast, d. H. order of  at man's height. The measuring point should be placed high enough that the mast area, in which mainly damage above the Erdoberkan te occur below the measuring position. It is therefore abbreviated from an upper one and lower measuring point or spoken of an upper and lower measurement, if according to the invention from the measurement "at a greater distance" from or "in the Near the top of the earth.

The "simultaneous" summarization of the measurement results in a diagram is important tet within the scope of the invention that the measured data all over the same time axis, even if the individual measurements (below and above on the mast) not at the same time but with a time delay. The measurements above and at the bottom of the mast can be carried out "at the same time" within the scope of the invention, if the respective mast positions (under - possibly changing - Bending load), e.g. B. with separate sensors or with one of several measurement positions same scanning camera, can be determined at the same time. From "time-shifted" Mes Solutions are spoken within the scope of the invention if the measurements are made on the different measuring positions one after the other, e.g. B. by shifting a path sensors. "Time-shifted" also means that in the multiplexer drive, e.g. B. with an alternating data at the different measuring positions determining measuring beam - for example at intervals of 20 msec. - is working.

If the course of the mast deflection in the vicinity caused by a bending load height of the floor and at a distance from the floor in a multiplex receiver is measured, the measurement result can be in a - the horizontal Layer - to be applied directionally. It can turn out in individual cases len that the mast deflection near the floor in another direction ver runs as the one at a distance from the ground. It can be used this way during the Deflection process measuring point-for-measuring point two in different directions directional measuring beams emanating from the same center men. The angle between the two measuring beams gives a measure of the Torsion on the mast at the respective load acting from one side experienced between lower and upper measuring point. In principle, it doesn't play a role le which of the sensors or sensor pairs mentioned above is used.  

However, the sensors should, at least together, be at least two-dimensional le measurement can be carried out in a substantially horizontal plane.

According to the invention, several results can be obtained with an increasing mast load in a single direction:

• 1. a: The mast deflection on the sensor positioned at a distance from the floor and the mast deflection on the sensor positioned near the floor measured with reference to a changing bending load. The difference of this The net mast bending described below gives values; Mast loads in two or more directions are not required.
• 2. b: The torsion of the mast between the lower and the upper measuring position and although with regard to the anchorage location is also with reference to one in egg ner direction changing bending load determined. If the door area ei ne could play a crucial role, can also be a measuring point in the door be provided richly; instead of the additional measuring point, the one z. B. the lower, measuring point can also be moved to the door area.
• 3. c: By forming the difference between the upper and lower measurement results According to a) and / or b), deflection and torsion of the mast can be made within of the soil with maximum force.
• 4. d: As I said, the bending load can be introduced both continuously and discontinuously the. By initiating a mechanical vibration, e.g. B. by a pump de Increasing the bending load (with each following a pressure rise phase Recovery phase) with the help of a hydraulic pump, the middle mast movement (when deflecting or springing back), a fine structure of Waves or the like. Superimposed to record with the same sensors as before men is; from the oscillation frequency and from the decay time of the oscillation conclusions can be drawn about the stability of the mast.
• 5. e: From the course dependent on the non-linear course of the increase in the bending load The course of the deflections or torsions of the mast can affect the free Game of mast anchoring in the ground can be concluded. The observer processing of the above-mentioned fine structure of the measured course of the mast movement This enables a short abbreviation of the examination of the individual mast and  again a reduction in the single test only from one Rich stress on the mast.
• 6. f: When observing the fine structure of the course of the mast movement as Ant word on an inconsistent increase in the bending load can be caused by the individual successive pressure rise phases each reached deflections of the Masts can be compared, alternatively or additionally, the Sequences of the successive recovery phases checked and with each other be compared. If there are deviations from a theoretical or practically determined standard, can often shortly after the start of the test process, the tested mast is in order or defective. In at In the cases, the test time is shortened, especially in the former case comes as gün Stig add that the inspection of the mast already with a relatively low mast load stung (= stress exerted on the mast) can be successfully ended.
• 7. g: When a mast is free to return following the application of a bending load can swing, he then usually leads a damped Eigen vibration off. Such a natural vibration occurs when the deflection te mast is suddenly relieved at the end of the test and freely towards swings back to its original position. Such a natural vibration but can also in each recovery phase of the aforementioned fine structure Mast movements occur when the bending load increases. In both The course of the more or less quickly decaying Eigen leaves cases vibration, for example by comparison with a practical or theoretical determined norm, a judgment on the mast quality.
• 8. h: Also by deliberately initiating a mechanical vibration, e.g. B. by an imbalance circling around the mast or by another vibration generator, the mast is set in vibration with the same Senso ren as previously recorded; from the vibration measured on the mast frequency and the decay time of the oscillation allow conclusions to be drawn pull the stability of the mast.

An error, e.g. B. a rust or crack, d. H. ultimately a damaged area with redu graced cross-section, usually has a torsion of the mast in response to one bending load (acting from one direction from the outside). When a  Torsion - by sensors above and below the damaged area - is measured and a corresponding error is visible on the mast above the top of the earth by moving the position of the sensors the effect of this error in the knife result can be eliminated. If there is still a torsion between measuring points - So a torsion occurs at the upper measuring point relative to the lower measuring point this is an indication of an invisible error.

In principle, these measurements according to the invention can give the same result sen lead if not the measuring points of the sensors but the point of attack of the external bending load, e.g. B. in the area once above and once below the door opening to be relocated. In all cases, according to the invention, a prediction is about externally invisible damage - usually with increasing Mast load in one direction and several simultaneous measurements above and below - possible.

If there is mast twist at the lower measuring point, i. i.e. when the mast steering deviates at this point from the direction of the introduced bending load this is an indication of a - usually also invisible - weakening in the Mast or its foundation in the area below the lower measuring point, ie mostly below the top of the earth. By comparing the invention upper and lower measurement it is also surprisingly possible to determine the state of the Above-ground part of the mast on its own, ie "corrected" from errors in loading rich below the top of the earth, based on quantitative measurements exactly, d. H. numerically to describe. As I said, in the ver drive the measurement and its recording so that not only from Area below the top of the earth due to defects but also on the mast externally visible errors in the measurement result are eliminated in such a way that invisible bare errors must be determined according to size, type and location.

The process according to the invention - with or without a mast - Stress reduction and measurement time reduction through observation of the fine structure - "Adjusted" measurement result in the above sense can also be briefly referred to as "net Mast bend ". The net mast bend then describes according to the invention  identified errors in the mast, which are not according to conventional methods were to be separated from interference of all kinds. The method according to the invention it is possible for the first time, for example, to make mistakes on poorly anchored masts to identify or localize in the above-ground part of the mast. After the invent According to the inventive method, it is also possible to use the so-called mast reserve. H. to determine the maximum bending strength of a mast, because if the net mast bend can be specified as part of the total bend the difference between the total bend and the net Record the mast bend exactly. In this way you can predict whether it is permissible for static reasons to add an existing mast Traffic sign or the like - which represents a significant wind resistance - may attach.

Based on the schematic representation in the accompanying drawing, eini ge details of the invention explained. Show it

Fig. 1 is a graph with the applied for an increasing bending load in function of time mast deflection;

Fig. 2 is a plot of the deflection of two spaced superposed positions of the mast projected on an approximately horizontal plane and, starting from the center line of the mast; and

Fig. 3 shows an example of the fine structure of the mast movement with pumping test pressure increase.

In the diagram according to FIG. 1, the time (for example in msec) is given in the abscissa and the mast deflection (for example in mm) in the ordinate. Three superimposed curves are shown. The top curve, labeled 1, describes the mast deflection determined on the basis of an increasing bending load at the upper measuring point of the mast. The middle curve, labeled 2, denotes the mast deflection measured at the same bending load as above for a lower measuring point. The lower curve, labeled 3, is nothing more than the point-by-point difference between curves 1 and 2 .

The curves show a fine structure in the form of a wavy line, which results from the fact that the bending load in the test result shown is not continuous but increased as part of a hydraulic pump movement with the visible frequency. In curves 1 to 3 , several successive areas are to be distinguished. In area A there is initially no deflection with a still small bending load, and a distinction between curves 1 and 2 cannot yet be seen. Then there follows a section B with a relatively steep increase in the deflection. The high speed of the deflection in this area stems in the game Ausführungsbei that initially a compaction of the floor area surrounding the mast foot occurred. When the ground area is compacted, the mast deflection in area C increases largely linearly at a lower speed. In the example, an intermediate region D then follows, which was created in the special experiment shown in that the increase in the bending load was temporarily slowed down.

In the drawing of FIG. 1 there is a reduction in the deflection in region D because the bending load was generated with the aid of a hydraulic drive and the pressure in the hydraulic cylinder dropped due to leakage. The intermediate rise area D is followed by the further rise area E, the slope of which corresponds to that of the area C and which finally ends in the saturation area F. The areas A to F occur in the three curves 1 to 3 . B describes above all a compaction in the ground area, C and E above all describe the mast deflection. Remarkable within the scope of the present invention is the difference curve 3 , which describes the mast bending of the above-ground mast part, which is adjusted by movements of the mast in the floor area, depending on a rising bending load acting from one direction.

In Fig. 1, the amounts of mast deflection are plotted regardless of the respective direction of the deflection. A drawing containing the mast deflection by amount and direction is given in FIG. 2. Fig. 2 contains the four partial representations a to d. In all cases, a plane perpendicular to the central axis 11 of the mast 12 is shown. It is believed that the bending load from Rich device 13 acts. The concentric circles around the axis 11 give a measure of the amount of the measured deflection. In the in Fig. 2a to d, the deflections are summarized at the upper and lower measuring point.

Fig. 2a shows a representation of the deflection of a mast 12 , in which the mast itself and its foundation are good. The maximum deflection 14 (corresponding to the area F of FIG. 1) is relatively small. The direction of the deflection 14 at the upper measuring point of the mast and the direction of the deflection 15 at the lower measuring point of the mast coincide with one another and with the direction of the bending load 13 essentially.

In the measurement result according to FIG. 2b, the mast 12 has drifted to the left under the effect of the bending load 13 . It can be concluded from this that the mast foundation is relatively weak. Because of the movement of the mast 12 , the deflections 14 and 15 have approximately a hysteresis shape.

Fig. 2c shows a measurement example in which the mast 12 is practically not displaced under the action of the bending load 13 , so it can be exposed to a relatively good mast foundation before. However, an angle w has been established between the deflection curves 14 and 15 , which indicates that the upper mast part is rotated under the action of the bending load 13 by the torsion angle w compared to the measurement on the ground (curve 15 ). The inspection in the present case showed that the torsion angle w was due to an existing door in the mast.

Another case is shown in FIG. 2d. This results in a measurement curve 14 with loop fenform. This strange shape is attributed to the fact that the mast has a lateral boom, e.g. B. had a whip shape, with attached at the free end Lam pe. This whip mast can vibrate when the bending load is applied or when it rises. These vibrations are characterized by the loop shape of curves 14 and 15 in Fig. 2d.

In Fig. 1, a steeply falling curve 4 follows the saturation region F. This falling curve 4 describes the period in which the bending load applied to the finished mast is suddenly switched off. Due to the sudden switching off of the bending load, the mast swings back (possibly beyond its original position; point 0 of the ordinate) and performs a damped oscillation 5 that has the same frequency at the upper and lower measuring point (curves 1 and 2 ) - but on upper measuring point has a larger amplitude.

Fig. 3 shows an embodiment of the so-called fine structure of the increase in mast deflection in response to a periodic increase in the bending load. In the exemplary embodiment it is assumed that the bending load increases pumping with a constant period and amplitude. However, this embodiment of the invention is not limited to a strict periodicity or constant amplitude. In terms of solving the task mentioned at the outset, valuable conclusions can be drawn from the fine structure even if the increase is not periodic and does not take place with a constant amplitude. If necessary, e.g. B. with the help of a Meßge advises downstream computer of fluctuating periods and amplitudes in the pressure rise originating mast deflections as well as when initiating a bending load constant period and amplitude.

In Fig. 3 the average course of the mast deflection at a measuring point (z. B. according to Fig. 1) is symbolized as a dash-dotted line 30 . In fact, the mast deflection changes along a wavy line 31 which characterizes the fine structure defined above. The wavy line 31 has an approximately sinusoidal shape in FIG. 3. It consists of curve parts 32 positive slope and dotted curve parts 33 negative slope. The wavy line 31 is delimited over part of its length between the enveloping tangents 34 and 35. The curve parts 32 of positive slope are forced by the increasing bending load. The curve parts 33 with a negative slope of the wavy line 31 arise when a recovery phase follows each time after an increase in the bending load, essentially without exerting any force on the mast. The curve parts 33 of negative slope can appear aperiodic, depending on the force curve and damping, have their own vibrations like the curves of FIG. 1 following the area F or otherwise fall in the direction of the enveloping tangent 35.

If the length of the curve parts 32 (rise phases in the direction of the ordinate y of FIG. 3) remains approximately constant or decreases with the time x and if the course of the wavy line 31 otherwise looks approximately as periodic as would correspond to a periodic input of the bending load , - can be assumed - often long before the intended maximum load is reached - that the tested mast still has the required stability and stability. If, however, deviations between the course of the bending load input and the mast movement response can be seen and / or if the wavy lines 31 determined at the various measuring points of the mast being tested (as shown by way of example in FIG. 1) diverge, then any deficiency in the mast can be closed. This determination can often be made long before the maximum bending load is reached. The measurement result is then much earlier and with significantly less mast load than in the prior art.

If the curve parts 32 positive slope in the course of the wavy line 31 (in direction y) become longer, this indicates that the mast deflection is greater when the bending load is unchanged compared to the previous course. Such enlarged curve branches 32 a indicate that the tested mast can no longer withstand the applied bending load properly, it is to a certain extent too soft. In this area, the curve parts 33 with a negative gradient also become relatively short (in the y direction) if such a soft mast springs back only slightly. If such a deviation, e.g. B. determined with kink 36 , can be said long before reaching the maximum mast load - ie after a short measurement time - that the tested mast is not in order.

The one for generating and evaluating the fine structure of the increase in mast weight The required non-linear increase in the bending load can easily be done with Generated with the help of a hydraulic hand pump. In this case they correspond Pump pressure rise phases while depressing the pump lever  the recovery phases coincide with the time when the pump lever is raised again becomes. With a hand pump, for example, a pressure can occur with each pump stroke increase of 10 kg can be achieved. A pump frequency may come with an order of magnitude of one pump stroke per second. Naturally motor pumps can also be used.

LIST OF REFERENCE NUMBERS

1-3

curves

4

sloping curve

5

damped vibration

11

axis

12

mast

13

bending load

14

Mast deflection above

15

Mast deflection below

30

average course of mast deflection

31

wavy line

32

positive slope

33

negative slope

34

.

35

enveloping tangents

36

kink

Claims (10)

1. Method for checking the stability and bending strength of a mast anchored at the mast base in the bo ( 12 ) using a force unit with which a bending load ( 13 ) acting in a direction of force is introduced into the mast and the mast is thereby loaded with a bending moment , and a displacement sensor for measuring the deflection of the mast caused by the bending moment, characterized in that the mast deflection ( 14 , 15 ) caused by the bending load ( 13 ), depending on the amount and possibly the direction, is near the top of the earth and at a greater distance from the top of the earth is measured and that the measurement results recorded in this way are summarized at the same time point-by-point in a common diagram. 2. The method according to claim 1, characterized in that the bending load ( 13 ) is pumped with each following a pump pressure rise phase Erho development phase and that the mast movement caused by a pressure rise is measured. 3. The method according to claim 2, characterized in that a fine structure the mast movement during the fol lowing to the respective pressure rise phase right recovery phase is measured. 4. The method according to claim 2 or 3, characterized in that the individual deflections ( 32 ) of the mast ( 12 ) each achieved by successive pressure rise phases are compared with one another. 5. The method according to at least one of claims 2 to 4, characterized in that the courses of the successive recovery phases of the mast deflection ( 33 ) are compared. 6. The method according to at least one of claims 2 to 5, characterized in that a natural oscillation of the mast ( 12 ) occurring in a recovery phase of the mast deflection ( 33 ) is measured. 7. The method according to at least one of claims 1 to 6, characterized records that the measurement near the top of the earth is about a hand's breadth running above the ground. 8. The method according to at least one of claims 1 to 7, characterized records that the measurement at a distance from the ground at about man height, ins especially clearly above an existing inspection door. 9. The method according to at least one of claims 1 to 8, characterized in that the mast deflection caused by the bending load ( 13 ) ( 14 , 15 ) is measured by amount and direction at the same time in the vicinity of the top of the earth and at a greater distance from the top of the earth. 10. The method according to at least one of claims 1 to 9, characterized in that the mast deflection caused by the bending load ( 13 ) ( 14 , 15 ) is measured in terms of amount and direction staggered near the top of the earth and at a greater distance from the top of the earth ,