A METHOD FOR STABILIZED MOUNTING OF SUBTERRANEAN FIXPOINT MARKERS

Abstract: After the mounting of short, rodshaped fixpoint markers in the underground it may happen, though exceptionally only, that a marker (14) is displaced or tilted by a local displacement of or in a thin earth layer around the marker. In order to counteract such displacement of the marker the marker is mounted in a hole in the ground inside a bucket like member (2), which is provided with a depending spear (4), which is hammered or pressed into the ground underneath the said hole. The long spear will stabilize the position of the bucket member in the ground, and the marker can be mounted with correct orientation irrespective of the final orientation of the bucket member.

Description: A Method for Stabilized Mounting of Subterranean Fi xpoi nt Markers . The present invention relates to a method of mounting a fixpoint marker in a stable and accurately oriented position in the underground. E.g. from WO/83/ 01306 and WO/83/03134 it is known to mount in the ground such markers, which are shaped as rod elements, the length axis of which intersects the overlying ground surface in a fixpoint, which can be localized with the use of a suitable electrical search detector, which is moved over the area such that an associated measuring instrument will indicate the position of the detector when located just above the fixpoint. For a correct fixpoint marking it is important that the marker below the specific point is mounted in the ground in such a manner that the electrical or electromagnetic axis of the marker is oriented accurate¬ ly vertically, since the position of the detected fi - point on the surface may otherwise be dependent of the surface undergoing elevation or lowering after the mounting of the marker. However, some types of areas exist, e.g. stretches of meadow land, in which local displacements of sub¬ terranean layers may occur, and it would be desirable, therefore, that the marker rod be stabilized by being incorporated in a rigid structure stretching across more "layers", principally by the rod being prolonged into a strong pole of the required length. Such a pole could be rammed down until the marker itself has reached the des red mounting depth, from wh ch the pole would then project further downwardly. For such a stabilized mounting of the marker, how¬ ever, it is a problem that the mounting, as mentioned, should take place with a quite accurate orientation of the marker, and it cannot be taken for granted that a pole can be rammed down with any sufficiently accurate orientation, as it will easily go slanting, e.g. already by hitting a stone. Moreover, the marker might get damaged by the impacts occurring during the ramming work. A possible usable solution would be to dig or drill a broad hole in the ground having the required, relative¬ ly large depth and then lower the pole into the hole, whereafter the pole could be held in an accurate ver- tical position while the hole is filled up with a suitable infill material around the pole. This, however, would be a both expensive and laborious method. The present invention makes use of both a down- ramming and a "broad-hole-mounting", in combination, inasfar as a hole is made, which is somewhat broader than the marker and as deep as the desired mounting depth of the marker, whereafter an upwardly open, bucket like member is lowered into the hole, the opening of the bucket member being both longer and broader than the marker rod, and the bottom of the bucket member being provided with a downwardly project¬ ing spear; the bucket member is hammered or pressed right down to the bottom of the hole, such that the spear will project therefrom further down into the ground, and thereafter the marker rod is lowered into the bucket member for stabilized mounting therein with an accurate orientation as controllable from above, irrespective of the actual orientation of the bucket member, preferably by filling down an infill material in the bucket member while the marker is held from above, whereafter the remaining hole is filled. Hereby the "pole portion" may be rammed or pressed down with high power without any risk of the marker being damaged and without any particular care having to be taken for achieving any accurately vertical orientation of the spear portion. Because the bucket member is broader than the marker rod there wi ll be space enough to enable the marker rod to be guided into a vertical position in the bucket member, even when the latter should end up in an inclined position at the bottom of the mounting hole, e.g. due to the spear having hit a stone during the ramming down. The marker wi ll not have to be strong¬ ly anchored to the pole and bucket portion, since upon its mounting it wi ll be entirely housed in and protected by the surrounding bucket member, which, itself, is anchored to the spear portion. The invention, which is defined in the appended claims in accordance with the above, wi ll now be de¬ scribed in more detai l with reference to the drawing, in whi ch :- Fig. 1 is a perspective view of a pole unit for use with the mounting of a marker, Fig. 2 is a sectional view of the upper end of the pole unit, and Fig. 3 is a sectional view of a ground area, for i llustration of the method according to the invention. The pole unit shown in Fig. 1 consists of an upper bucket member 2 of plastic, the bottom of which is rigidly provided with a depending earth spear 4, e.g. of anti-corrosion treated steel. As shown in Fig. 2 the upper end of the earth spear penetrates the bottom of the bucket member and is provided with a centering opening 6 for receiving a lower pin portion 8 of an upper rod tool 10. This rod is used as a pressure tool for driving the spear 4 into the earth, such that the bucket member 2 is not damaged by the required pressing or hammering forces. For mounting a marker a hole 12 is first dri lled or pressed out in the ground, see Fig. 3, the hole be¬ ing made with a diameter slightly larger than the outer diameter of the bucket member 2 and with a depth corre¬ sponding to the desired mounting depth of the marker, e.g. 1.2 m. Thereafter the pole unit 2,4 is lowered into the hole unt l the spear 4 abuts the bottom of the hole. Then, by means of the rod tool 10, the spear is pressed or hammered further down, until the bucket member 2 reaches the bottom of the hole 12. It will hereby be unimportant whether the spear should go some¬ what slanting, as illustrated to the left in Fig. 3. Upon upward retraction of the rod tool 10 a marker 14 is now lowered into the hole 12, held by lower gripping means 16 on a mounting rod 18, the top end of which is provided with a level 20 and a release handle 22 for the gripping means 16. The marker 14, the diameter of which is considerably smaller than the inner diameter of the bucket member 2, is lowered down into the bucket member, and on the level 20 it is checked that the orientation of the mounting rod 18 and there¬ with of the marker 14 is accurately vertical, whereafter a suitable infill material s filled into the hole 12 sufficiently to fill out the free space around the marker in the bucket member, such that the marker is stabilized in its vertical position. A fine gravel material with sharp grains is well usable for such stabilizing in¬ filling. Thereafter the gripping means 16 are released by actuating the release handle 22, and the mounting rod 18 is pulled up, whereafter the remaining hole s f lled up with a suitable material, e.g. the drilled up earth as designated 24 in Fig. 3. It will be appreciated that the achieved stabilized mounting of the marker will not require any kind of modification of the marker and that the mounting of the marker itself can be effected in the same simple manner as by an ordinary, non-stabilized mounting direct in a hole n the ground. It will be within the scope of the invention to pro¬ vide the bucket member 2 with an angularly adjustable receiver socket for the marker, such that the latter can be introduced from above and finally orientation ad usted from above prior to a subsequent filling up of the hole, but when the mounting can be effected as simply as described in the foregoing the use of such special devices will normally be superfluous and un¬ necessarily costly. It should be mentioned that the earth spear 4 should not necessarily be mounted at the center of the bottom of the bucket member 2, as it may be placed e.g. at the outer periphery of the bucket member.

Claims: CLAIM : A method of mounting a rodshaped fixpoint marker in a stabilized and accurately oriented position in the underground, characterized by providing in the ground a hole which is considerably wider than the marker rod and reaches down to the desired mounting depth of the marker, whereafter an upwardly open bucket member is lowered into the hole, the inner opening of the bucket member being both longer and wider than the marker rod and the bottom of the bucket member being provided with a depending earth spear; the bucket member is hammered or pressed substantially down to the bottom of the mounting hole such that the earth spear projects further down into the ground, and thereafter the marker rod is lowered into the bucket member for stabilized mounting therein with an accurate orientation as controlled from above, irrespective of the actual orientation of the bucket member, preferably by filling down an infill material into the bucket member with the marker held from above in its desired orientation, whereafter the remaining hole is filled up,

Inventors: PEDERSEN WILLY PALLE, PEDERSEN, WILLY, PALLE
Applicants: PEDERSEN WILLY PALLE, PEDERSEN, WILLY, PALLE
Application year: 1985
Main classification: G01C15
IPC codes: G01C15