SE539385C2

SE539385C2 - Method of and device for installing a ground anchor comprising an expandable part

Info

Publication number: SE539385C2
Application number: SE1550905A
Authority: SE
Inventors: Blomberg Magnus; Nordell Lars-Erik
Original assignee: Grundtuben Ab
Priority date: 2015-06-29
Filing date: 2015-06-29
Publication date: 2017-09-05
Also published as: EP3314077A1; WO2017001506A1; SE1550905A1

Abstract

14 ABSTRACT The present disciosure reiates to a method of instaiiing a groundanchor comprising an expandahie part. The method comprises the steps ofdriving the ground anchor (i) into the ground (O), providing an expansion tooi(16) having an expansion member (i ia, ite), which is cperahie bypressurization of a tiuid, reading fiuid to the expansion tooi (10) such that theexpansion member (ite, tio) causes the expandabie part (3) to expand,during said feeding, measuring a fiow of the ﬂuid, and increasing a feedingpressure of the fiuid in response to a measured reduction of the fiow.

Description

1 METHOD OF AND DEVICE FOR INSTALLING A GROUND ANCHORCOMPRISING AN EXPANDABLE PART Technical fieldThe present disclosure relates to a method for installing a groundanchor comprising an expandable part, and to a device for installing such a ground anchor.

BackgroundGround anchors with underground expandable parts are commonly used today for supporting and reinforcing structures and buildings and otherstructures, such as fences, aerials, monuments, etc.

A ground anchor with expandable part is for example shown inEP0820550B1, the entire content of which is incorporated herein byreference, as is a method of its expansion.

Installation ofground anchors by means of a hydraulic pump isassociated with relatively high forces and pressures. Such high forces andpressures are associated with wear on the tools used for installation.

There is a need for reducing wear on the tools, as this would lead toincrease uptime of the equipment and thus a more efficient installation process.

Summarylt is an object of the present disclosure to provide a method of installing a ground anchor comprising an expandable part and to provide a systemcomprising such a ground anchor, which reduces the wear on the tooling.

The invention is defined by the appended independent claims.Embodiments are set forth in the dependent claims, in the attached drawingsand in the following description.

According to a first aspect, there is provided a method of installing aground anchor comprising an expandable part. The method comprises thesteps of driving the ground anchor into the ground, providing an expansion f' Å» “f-WQ“^"WÛJT^."'" "'1{\P“"'.“1:T yw~w~l~4 Ani-fl; H t ^TID '1 'IT 1 'i šwi .;...~ .;.. -.. eﬁﬁeﬂ lt l-.N ~..u. N logen. h., ~_ ;\.i \.\ ~. . . 2 tool having an expansion member, which is operable by pressurization of afluid, feeding fluid to the expansion tool (such that the expansion membercauses the expandable part to expand. During the feeding, the methodcomprises measuring a flow of the fluid and/or amount ofﬂuid fed, andincreasing a feeding pressure of the fluid in response to a measuredreduction of the flow.

The fluid may be a gas, such as pressurized air, or a liquid, such ashydraulic fluid. lt is understood that a the flow is the derivative with respect to time ofthe amount fed.

By starting out at a lower pressure and increasing the pressure duringthe installation, it is possible to utilize a lower pressure during most of theinstallation and thus only subject the expansion tool to a higher pressure ifand when this is necessary. Hence, wear of tool parts, in particular seals, maybe decreased, as may energy consumption.

The method may further comprise measuring a pressure of the fluidduring said feeding, A first phase of the feeding may be performed at a predetermined firstpressure.

Such predetermined pressure may be received as a user input, from adata memory as a universal default value or from a data memory in responseto an input or selection of ground anchor type and/or ground type.

A second phase of the feeding may be performed at a second pressure,which is higher than the first pressure.

The second pressure may be a predetermined second pressure. ln thealternative, the second pressure may be determined as a function of the firstpressure and/or as a function of a flow rate.

The pressure may be increased such that the flow is substantially maintained.

Hence, the second pressure may be dependent on the flow. That is,the second pressure may be provided as a function of the measured flow.The method may further comprise interrupting the feeding once apredetermined amount of fluid has been fed.

(Vi fr? "V1 '" 5"! *\~ l F'l ~M~~T1W ' r' 'f 10» w' ~G2\".?'f'^"I4l'\:T^."'" ”4ÛPTÛQF nwlV-f~ .. e.. _. i m; m.«.1. -Mi “why .|.;.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ^DTÉ.1°”JTQSÜ,'Ä*: : 3 According to a second aspect, there is provided a device for installing aground anchor comprising an expandable part. The device comprises anoperable expansion member, which is operable by pressurization of a fluid, afeeding device for feeding f|uid to the expansion member, a flow meter formeasuring the flow of f|uid fed to the expansion member and/or a volumemeter for measuring an amount of f|uid fed, and a pressure regulating devicefor regulating pressure of the f|uid fed to the expansion member, and a controldevice, adapted to receive a flow signal from the flow meter and/or a volumesignal from the volume meter, and to provide a control signal to the pressureregulating device based on the flow signal and/or volume signal, such that thepressure regulating device controls a pressure of the ﬂuid fed to theexpansion member based on the flow of the ﬂuid fed to the expansionmember and/or based on the amount of f|uid fed.

A "signal" may be any type of signal, whether provided electronically(analog or digital), optically, mechanically, acoustically or through a f|uid.

Thus, a “flow signal” is a signal indicating a measured flow and a“control signal” is a signal used to control the operation of the pressureregulating device.

The device may further comprise a pressure meter for measuring apressure between the feeding device and the expansion member, wherein thecontrol device may be adapted to receive a pressure signal from the pressuremeter.

The control device may be adapted to control the pressure regulatingdevice also based on the pressure of the -fluid fed to the expansion member.

According to a third aspect, there is provided a method of installing aground anchor comprising an expandable part. The method comprises thesteps of driving the ground anchor into the ground, providing an expansiontool having an expansion member, which is operable by pressurization of afluid, feeding f|uid to the expansion tool such that the expansion membercauses the expandable part to expand, during said feeding, measuring a flowof the f|uid and/or an amount of f|uid fed, during said feeding, measuring apressure of the fluid, and determining, based on the measured flow and/or (Vi fr? "i". '" 5"! *\~ l F'l ~n.--\'“-1\\ ' r' 'f 10» w' ~U2\-'.?'f“^"I4l'\š^."'" "'1{\P“"'.“'2F nwlV-f~ .. e.. _. i m; m.«.1. -My »fik-v .~.=.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ñøïšÅwjffQštÜq. i: : 4 amount ofﬂuid and on the pressure, whether the installation meets apredetermined strength requirement or not.

Hence, it is possible to provide, in real time, an indication to the effectthat the installation was successful or not. The determination may be basedon empirical data for different types of installation environments.

The method may further comprise interrupting said feeding when apredetermined pressure has been attained and/or when a predeterminedamount of fluid has been fed.

The feeding may be interrupted automatically, on reaching thepredetermined amount of fluid and/or the predetermined pressure. ln thealternative, an indication may be provided when the amount of fluid orpressure has been attained, whereby the user may, in response, interrupt thefeeding.

By such interruption, it is possible to reduce the risk of the toolsoverrunning. lt is also possible to automate the installation process.

The method may further comprise recording said measured flow and/oramounf of fluid fed and pressure in a data memory.

By recording such measured flow and/or pressure in a data memory, itis possible to derive an indication of the installation quality, i.e. it is possible tolearn whether a particular ground anchor has been properly installed. lf, e.g.the amount of fluid indicates complete expansion, and the greatest measuredpressure is too low, this would indicate that the ground anchor has notreached its maximum strength, e.g. as a result of the expansion having beenmade in a region where the density of the ground is too low. lf, on the otherhand, less than 100 % expansion is indicated by the amount ofﬂuid, while themaximum pressure has been reached, this may indicate that the groundanchor has been expanded in a region where the density is very high, e.g. inthe presence of rocks.

At least one of the measured flow and/or the amount of fluid fed, andthe pressure may be recorded as a data series comprising a plurality ofvalues taken at different points in time during the feeding. This would then enable detailed analysis of the expansion process.

(Vi fr? W". '" 5"! *\~ i F'l ~n.--\'“-1\\ ' r' 'f 10» w' ~U2\-'.?'f“^"I4l'\š^."'" "'1{\P“"'.“'2F nwlV-f~ .. e.. _. i m; m.«.1. -My »fik-v .~.=.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ÛDTÉÅfTTfQStÜQ. f: : 5 The method may further comprise deriving an amount of expansionbased on the amount of fluid that has been fed.

The method may further comprise providing a user indication based onthe measured pressure and/or flow and/or amount of fluid fed. Such a userindication may be an indication that the expansion process resulted in anacceptable anchoring or not, e.g. merely by a green or red lamp. As furtheroptions, the user indication may provide more details on e.g. what pressurewas reached and how much ﬂuid was fed or how much expansion was attained.

Brief Description of the Drawinqs Fig. 1 is a schematic view of a ground anchor system comprising aground anchor with an expandable part, in a non-expanded state.

Fig. 2 is a schematic perspective view of a ground anchor in anexpanded state.

Detailed Descriptionln Fig. 1, there is provided a schematic view of a ground anchor system, comprising a ground anchor 1 having one or more expandable parts3. Such a ground anchor 1 is shown in perspective view in fig. 2.

The ground anchor 1 may be driven into the ground 0 for example byscrewing or by hammering (not shown), both of which are per se knownmethods. A separate tool may be used for this driving process. For example,the ground anchor 1 may be driven into the soil by means of a pike which isdisposed in the tube, and which, after the tube has been driven in, is removedthere from. ln more dense soils, a pilot hole may initially be drilled into theearth before the ground anchor is inserted into the ground 0. As anotherexample, the ground anchor may be driven into the ground by simplyhammering on an uppermost portion thereof.

The expandable part 3 of the ground anchor may be made of aplastically deformable material, for example a steel tube with at least oneaxial slot 2 extending over part of the length of the steel tube, where the (Vi fr? "V1 '" 5"! *\~ i F'l ~M~~T1W ' r' 'f 10» w' ~G2\".?'f'^"I4l'\:T^."'" ”1ÛPTÛQF nwlV-f~ .. L.. _. i m; m.«.1. -Mi “why .|.;.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ÛDTÉÅfTTfQStÜQ. f: : 6 slotted region is to be driven into the soil 0. Expansion of the expandable part3 of the ground anchor 1 may be achieved by means of an expansion tool 10which is inserted into the ground anchor 1 after the ground anchor has beendriven into the ground 0. ln Fig. 1, there is i||ustrated a system for expanding an expandable part3 of the ground anchor disclosed in Fig. 1.

The system comprises a pump 20 with a supply of hydraulic fluid, suchas hydraulic oil, at least one expansion member 11a, 11b, such as a hydraulicpiston, a pressure meter 23 for measuring pressure in the hydraulic fluidsupplied to the expansion member and a flow meter 22 for measuring the flowof hydraulic fluid supplied to the expansion member 11a, 11b.

The system further comprises a pressure regulating device 21. Such adevice 21 may be implemented as an integral part of the pump 20, i.e. a feedrate or a displacement of a pump 20 may be controlled.

As an alternative, or supplement, the pressure in the hydraulic fluid fedto the expansion member may be controlled, e.g. by a throttle valve or avariable bypass valve, which may form part of the pressure regulating device21 _ The system further comprises a controller 24, which is connected tothe pressure meter 23, the flow meter 22, and the pressure regulating device21 _ The controller 24 may be provided with a plurality of functions forcollection of data related to the expansion of the expandable part 3.

For the present disclosure, the controller 24 may capable of receiving aflow signal from the flow meter 22 and a pressure signal from the pressuremeter 21. Moreover, the controller 24 may be capable of providing a controlsignal to the pressure regulator 21 _ Moreover, the controller 24 may be capable of receiving controlparameters, e.g. as a result of a user input, received from a database basedon e.g. a type of installation to be made, or received or derived based datacontained in an identifier provided on the product, e.g. in the form of abarcode or an RFID device.

(Vi fr? "V1 '" 5"! *\~ l F'l ~M~~T1W ' r' 'f 10» w' ~G2\".?'f'^"I4l'\:T^."'" ”4ÛPTÛQF nwlV-f~ .. e.. _. i m; m.«.1. -Mi “why .|.;.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ^°Tš.1°”j7Q5Ü,'š*: : 7 The control parameters may comprise base pressure and flow valuesfor the supply of hydraulic fluid to the expansion member 11a, 11b.

The control parameters may also comprise threshold values, e.g.pressure and/or flow threshold values, determining at what points pressureand/or flow should be modified during expansion.

The control parameters may also comprise limit values, e.g. an upperpressure limit and/or a lower flow limit both of which may indicate thatexpansion should be interrupted.

The system may be operated as follows when installing a groundanchor.

The ground anchor 1 may be driven into the ground in the conventionalmanner.

Once the ground anchor 1 has reached the desired depth, theexpansion tool 10 may be inserted into the ground anchor 1 and its correctpositioning, e.g. its angular position relative to the ground anchor 1, may bevenﬁed.

Control parameters may be provided to the controller 24, e.g. by theuser selecting the relevant type of ground anchor to install and the controllerretrieving the control parameters from a data memory. ln its simplest form, thecontroller 24 may simply use a preprogrammed desired pressure and/or flowvalue.

The pump 20 is operated to feed pressurized hydraulic fluid to theexpansion member 11a, 11b at a first pressure. During the feeding, at leastthe flow, optionally also the pressure, is measured. The total amount of fluidsupplied to the expansion member 11a, 11b may be calculated based on theflow measurement.

When the flow drops below a predetermined threshold value, thusindicating that the pressure is not sufficient to continue expansion at the samerate, and the maximum amount of fluid has not yet been supplied, thepressure may be increased by the controller 24 providing a control signal tothe pressure regulator 21 to achieve a second pressure, higher than the first pressure.

(Vi fr? "V1 '" 5"! *X- i F'l ~m-~'“-1\\ ' r' 'f 10» w' ~U2\-'.?'f“^"I4l'\:'~"^."'" ”4ÛPTÛQJT nwlV-f~ .. e.. _. i m; m.«.1. -my “vi 1. -v -~.;.. -.. eﬂﬁeﬂ lt .-.v_ FIM. li~fl~ i-, f., ÛDTÉÅfTTfQStÜQ. f: : 8 The pressure may be maintained at the second pressure until completeexpansion has been attained, e.g. as derived based on the flowmeasurement. ln the alternative, the pressure may be further increased, optionally upto an upper pressure limit, which may be provided as a control parameter orby a safety valve, until complete expansion has been attained.

For example, the pressure may be continuously increased in order tomaintain a predetermined flow, until complete expansion has been attained.

The controller may be provided in the form of a programmablecomputer, or in the form of a dedicated circuit.

At least one of the pressure regulating device 21, the flow meter 22,the pressure meter 23 and the controller 24 may be integrated with the pump20, e.g. by being arranged in a common housing. As another option, at leasttwo of the pressure regulating device 21, the flow meter 22, the pressuremeter 23 and the controller 24 may be provided in a common housing that isseparate from a pump housing.

Measuring the flow and pressure provides further opportunities forreducing tool wear and quality control.

For example, by measuring pressure and flow when expanding theground anchor, it is possible to interrupt the expansion process when asufficient amount of expansion has been attained or when a predeterminedpressure has been attained. Thus, the risk of overloading the tool and/or overexpanding the ground anchor can be reduced, with further improvement oftool life as a result. Moreover, such measurement provides an opportunity forautomating the installation process, that is, a single user input may besufficient to start the expansion process, whereby the controller will interruptthe expansion process as soon as the predetermined pressure and/orexpansion have been attained.

The pressure and/or flow data may be recorded in a data memory,wherein it may be saved together with information uniquely identifying the associated ground anchor. Such data may be saved either as individual (Vi fr? W". '" 5"! *\~ l F'l ~n.--\'“-1\\ ' r' 'f 10» w' ~U2\-'.?'f“^"I4l'\š^."'" "'1{\P“"'.“'2F nwlV-f~ ,. e.. _. i m; m,«.1. -My »fik-v .~.=.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ÛDTÉÅfTTfQStÜQ. l: : 9 values, such as maximum pressure during expansion and/or total amount offluid provided.

As another option, the data may be recorded as data series comprisinga p|ura|ity of values taken at different points in time during the expansionprocess. This would then enable evaluation of the process with a view tofinding any abnormalities which may have occurred during the expansionprocess. lt is also possible to derive an amount of expansion based on theamount of fluid that has been fed. This amount of expansion may bepresented as a percentage of maximum expansion, the percentage beingderived based on the amount of fluid that would normally be fed to achieve100 % expansion.

Moreover, it is possible to provide a user indication based on themeasured pressure and/or flow. Such a user indication may be a real timefeedback that the expansion was successful or unsuccessful. The indicationmay also be recorded in a data memory, such that it will be possible to laterdetermine what the operator knew about the installation. lt is possible to empirically determine, for different types of installationenvironment (soil, ground type), strength properties for ground anchors as afunction of amount of expansion and/or as a function of expansion pressureor maximum expansion pressure. Such empirical data may to some extent beinterpolated or extrapolated to provide more general rules for what propertiesare achieved.

Hence, the determination on whether a measured and/or derivedpressure and/or expansion amount is acceptable or not, may be made subjectto ground type and strength requirement.

While the description above refers to measurement of the flow andintegration of the flow to derive an amount of fluid that has been fed, it isunderstood that it is possible to additionally or alternatively measure thevolume that has been fed, e.g. by measuring a volume at a ﬂuid sourceand/or a position of the expansion member, whereby the amount of fluid thathas been fed to the expansion member can be directly measured. ln order to (Vi fr? "V1 '" 5"! *\~ l F'l ~M~~T1W ' r' 'f 10» w' ~G2\".?'f'^"I4l'\:T^."'" ”4ÛPTÛQF nwlV-f~ .. e.. _. i m; m.«.1. -My “why .|.;.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ^°Tš.1°”j7Q5Ü,'š*: : derive a flow rate, the flow rate may be derived as the derivative over time(dV/dt) of the amount of fluid fed.

(Vi fr? "V1 '" 5"! *X- i F! ~m-~'“-1\\ ' r' 'f 10» w' ~U2\-'.?'f“^"I4{\:T^."'" ”'1{\P'"9QF ywtf-fáí» f» i- ÛDÄE1'F“7QK'" 'l 4» «~ ,. e.. _. \ m; m,«d. -My “dh-v _-.;.. -.. =.._e.\ lt u. VM. » i., .mf _ ~\.\,.,.

Claims

1. A method of installing a ground anchor comprising anexpandable part, comprising the steps of: driving the ground anchor (1) into the ground (O), providing an expansion tool (10) having an expansion member (11a,11b), which is operable by pressurization of a fluid, feeding fluid to the expansion tool (10) such that the expansionmember (11a, 11b) causes the expandable part (3) to expand,during said feeding, measuring a flow of the fluid and/or an amount of fluid fed, measuring a pressure of the fluid during said feeding, and increasing a feeding pressure of the fluid in response to a measured reduction of the flow.

2. The method as claimed in claim 1, further comprisinginterrupting the feeding once a predetermined pressure has been achieved.

3. The method as claimed in claim 1 or 2, wherein a first phase of the feeding is performed at a predetermined first pressure.

4. The method as claimed in claim 3, wherein a second phase ofthe feeding is performed at a second pressure, which is higher than the first pressure.

5. The method as claimed in any one of the preceding claims,wherein the pressure is increased such that the flow is substantially maintained.

6. The method as claimed in any one of the preceding claims,further comprising interrupting the feeding once a predetermined amount offluid has been fed. (Vi fr? "V1 '" 5"! *\~ l F'l ~M~~T1W ' r' 'f 10» w' ~G2\".?'f'^"I4l'\:T^."'" ”4ÛPTÛQF nwlV-f~ .. e.. _. i m; m.«.1. -Mi “why .|.;.. -.. eﬂﬂeﬂ lt l-.N VIN. li~fl~ i-, f., ^°Tš.1°”j7Q5Ü,'š*: : 12

7. The method as claimed in any one of the preceding claims, wherein the fluid is a hydraulic fluid.

8. A device (10) for installing a ground anchor (1) comprising anexpandable part (3), the device comprising: an expansion member (11a, 11b), which is operable by pressurizationof a fluid, a feeding device (20) for feeding the fluid to the expansion member(11a, 11b), a flow meter (22) for measuring the flow of fluid fed to the expansionmember (11a, 11b), or a volume meter for measuring an amount of fluid fed, a pressure regulating device (21 ) for regulating pressure of the fluid fedto the expansion member (11a, 11b), and a control device (24), adapted to receive a flow signal from the flowmeter (22) and/or a volume signal from the volume meter, and to provide acontrol signal to the pressure regulating device (21) based on the flow signaland/or volume signal, such that the pressure regulating device (21) controls apressure of the fluid fed to the expansion member (11a, 11b) based on theflow of the fluid fed to the expansion member (11a, 11b) and/or based on the amount of fluid fed.

9. The device as claimed in claim 8, further comprising a pressuremeter (23) for measuring a pressure between the feeding device (20) and theexpansion member (11a, 11b), wherein the control device (24) is adapted to receive a pressure signal from the pressure meter (23).

10.(24) is adapted to control the pressure regulating device (21) also based on The device as claimed in claim 9, wherein the control device the pressure of the fluid fed to the expansion member (11a, 11b). (Vi fr? "V1 '" 5"! *X- l F'l ~m-~'“-1\\ ' r' 'f 10» w' ~U2\-'.?'f“^"I4l'\:T^."'" ”4HPTÛQJT ywlf-fli» f» i- ÛDÄE1'F“7QK'" 'l 4» «~ ,. e.. _. i m; m,«d. -My “dh-v _-.;.. -.. =.._e.i lt .-.v_ VIN. » i., .mi _ ~\.\, . ,. 13

11. expandable part, comprising the steps of: A method of installing a ground anchor comprising an driving the ground anchor (1) into the ground (O), providing an expansion tool (10) having an expansion member (11a,11b), which is operable by pressurization of a fluid, feeding fluid to the expansion tool (10) such that the expansionmember (11a, 11b) causes the expandable part (3) to expand, during said feeding, measuring a flow of the ﬂuid and/or an amount offluid fed, during said feeding, measuring a pressure of the fluid, anddetermining, based on the measured flow and/or amount of fluid, and on thepressure, whether the installation meets a predetermined strengthrequirement or not, and deriving an amount of expansion based on the amount of fluid that hasbeen fed.

12. interrupting said feeding when a predetermined pressure has been attained The method as claimed in claim 11, further comprising and/or when a predetermined amount of fluid has been fed.

13.recording said measured flow and/or amount of fluid fed, and pressure in a The method as claimed in claim 11 or 12, further comprising data memory.

14. least one of the measured flow and/or amount of fluid fed and the pressure is The method as claimed in any one of claims 11-13, wherein at recorded as a data series comprising a plurality of values taken at differentpoints in time during the feeding.

15. comprising providing a user indication based on the measured pressure The method as claimed in any one of claims 11-14, further and/or flow and/or amount of fluid fed. (Vi fr? W". 'T 5"! *K- l F'l ~n1-~'“-1\\ ' r' 'f 1G» w' ~U2\".?'f“^"I4l'\:T^."'" ”4ÛPTÖQJT nwlV-fái» f» i- ÛDM1ÅVT7QKT 'l l» «~ .. e.. _. i m; m.«.,. -Mi »Inn-v .-.;.. -.. e.._e.i lt l-.N VIN. » f., .mf _ ~\.\, . ,.