DE1271045B - Method for producing ground anchors - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 40STW ^ PATENT OFFICE

EDITORIAL

Int. Cl .:

E02d

German class: 84 c-5/56

Number:
File number:
Registration date:
Display day:

P 12 71 045.1-25
April 6, 1965
June 20, 1968

The invention relates to a method for producing ground anchors in non-rocky or rough Soils interspersed with rock, in which a tension member is inserted through a hollow drill rod. The procedure relates to permanent or temporarily installed ground anchors subject to tensile stress in a horizontal, inclined or vertical direction for anchoring structures or components in the ground.

There are methods of making also on train ίο loaded piles known. Usually large-volume piles produced using such methods, their insertion lead to a considerable disturbance of the ground driven through, but are not suitable for soils with low internal friction, since the introduction of force also occurs when a pile base is formed largely over the entire outer surface of the pile over its entire length due to friction on the borehole wall he follows. Tension piles and methods for their manufacture are therefore neither in their intended use can still be compared in their effect with ground anchors.

The German patent specification 1104 905 discloses a method for producing injection tie rods known, after a hole with the smallest possible cross-section with a hollow drill pipe driven behind the sliding surface of the active earth pressure, a tie rod, consisting of a tension member, which is connected to a drill bit serving as an abutment, introduced and then the Surrounding the abutment is pressed with hardening building materials. This procedure takes place with great Success especially in cohesive soils, in which the soil is penetrated with injection material possible in the area of the force introduction path to form a pear-shaped abutment is.

In strongly cohesive soils, however, the formation of such an abutment is only of limited size possible, so that the transfer of forces from the abutment despite great adhesion between anchor and concrete only limited tensile forces are permitted on the surrounding soil.

The invention is based on the problem of binding the disadvantages of the known method Avoid soils with relatively low internal friction and to initiate larger ones To extend tensile forces in cohesive soils with relatively low internal friction.

The solution to this problem is seen in the method according to the invention that a non-conveying steel helix by means of the loosely attached method for producing ground anchors

Applicant:

Dr.-Ing. Karl-Heinz Bauer,

8898 Schrobenhausen, Wittelsbacherstr. 5

Named as inventor:

Dr.-Ing. Karl-Heinz Bauer, 8898 Schrobenhausen

connected hollow drill pipe into the ground with simultaneous grouting of hardening Building materials screwed into the passage space of the steel helix up to a precalculated end position is inserted, the tension member through the drill pipe and firmly connected to the steel helix the steel helix then without rotation with a tensile force applied to the tension member by a certain amount Measure is withdrawn, the cavity forming in front of the steel helix with hardening The building materials are pressed out and the steel helix is turned back into the end position, then the drill rods expanded and the space between the tension member and borehole wall simultaneously with hardening Building materials are filled and the ground anchor is prestressed after the building materials have hardened.

Depending on the geological conditions, the injection is preferably not carried out until the advance of the Steel helix has penetrated the statically required force application area.

In the case of particularly cohesive soils, it is advantageous to avoid the effects that arise when the steel helix is withdrawn To ventilate the cavity and this cavity only after the steel helix has been brought back in to press the end position with hardening building materials.

The geological conditions give rise to the fear that when the steel helix is withdrawn forming cavity does not stop, this cavity is simultaneously with the retraction of the Steel helix pressed with hardening building materials.

With appropriate geological conditions, it can also be advantageous to use the cavity at the same time with the renewed bringing forward of the withdrawn steel helix with hardening building materials press.

Under certain geological conditions it may also be useful to withdraw the

809 560/137

To do without steel helix completely after reaching the end position.

Dispersions of rubber are preferably added to the grout made from hardening building materials mixed in.

According to an exemplary embodiment explained in the accompanying drawing, a steel helix with a handle and a diameter of 300 mm on a drill pipe of 100 mm outer diameter used. A prestressing steel with a diameter of 50 mm is selected as the tension member. It shows

F i g. 1, partly in section, loosely on the hollow drill pipe seated steel helix, with a handle,

F i g. 2 the steel helix with drill rods in the final drive position,

F i g. 3 the position of the steel helix after retraction,

F i g. 4 the finished, pre-stressed ground anchor after the drill rod has been removed.

The steel helix 1 (FIG. 1) has a thread 2, outlet openings 3 for injection material and a hole 4 provided in the helical hub. The steel helix 1 sits loosely in guide grooves 5 on the Drill rod 6.

The steel helix 1, which serves as an anchoring abutment, is mounted on a strong, hollow drill rod 6 mounted and using a high-performance rotary drill into the ground up to drilled into the statically appropriate end position. The steel helix 1 is short and designed so that when Screwing in no soil is promoted. The pitch of the steel helix 1 and the advance are set up in such a way that that the steel helix 1 is screwed in without mixing the soil in the passage area. The hollow drill rod 6 consists of relatively short pipe sections, which in the course of the screwing-in process are gradually screwed together.

The steel helix 1 is after passing through the sliding surface of the active earth pressure under simultaneous Grouting of hardening cement, possibly mixed with rubber dispersions, whereby the injection material is distributed in a spiral shape over the spiral passage (FIG. 2).

After reaching the end position, the drill rod 6 is flushed up to the steel helix 1 and the tension member 8, for example a prestressing steel, inserted through the drill rod 6 and into the thread 2 of the Steel helix 1 screwed in.

A hollow piston press, not shown, is then placed on the bore and with the hollow piston press the steel helix 1 using high forces of, for example, 1001 µm withdrawn to a certain extent (Fig. 3). When the steel helix 1 is withdrawn, it is in the passage area the soil and the injected material in between, while maintaining the The spiral is strongly compressed and laterally pressed into the zone surrounding the passage area. Simultaneously with the retraction of the cavity 7 is formed, which according to the embodiment at the same time with the Withdrawal of the steel helix 1 by introducing hardening building materials through the drill rod 6 and the outlet openings 3 is pressed out.

The retraction of the steel helix 1, which leads to a strong compression, solidification and lateral expansion the penetrated soil and the injection material as well as for the formation of the cavity 7 serves at the same time has the purpose of using the forces expended to withdraw evidence of the to obtain the final load capacity of the ground anchor.

After the steel helix 1 has been brought forward again (FIG. 4), the drill rod 6 is pressed and backfilling the hole. After the building materials have hardened, the ground anchor is pre-tensioned.

The tension member 8 is preferably with a smooth coating, for example made of plastic, up to the steel helix 1 coated. The coating serves on the one hand as corrosion protection of the tension member 8 in permanent anchoring, on the other hand, it is necessary to reduce friction between tension member 8 and surrounding building material and to avoid indirectly to the ground.

The steel helix 1 serving as an abutment thus sits in an abutment block made of concrete. The on Due to the complete isolation of the tension member 8, force introduction concentrated exclusively on the steel helix 1 the tensile forces cause the load on the solidified soil area via the abutment block. A pulling out of the anchorage is in contrast to the known tension piles and injection anchors not likely, even in soils with low internal friction, since the application of force not in the longitudinal direction to the anchor axis due to friction, but mainly at an angle across the surfaces the filled pressure spiral takes place. It is particularly advantageous in tough soils that the Propulsion of the steel helix 1 the ground inside and outside the passage cross-section of the steel helix 1 is not disturbed.

Claims (7)

Patent claims: 1. Method for producing ground anchors in non-rocky or interspersed with coarse rock Soils, in which a tension member is introduced through a hollow drill pipe, thereby characterized in that a non-conveying steel helix by means of the hollow drill rod loosely connected to it into the ground while simultaneously pressing hardening building materials into the passage area of the Steel helix is screwed in to a pre-calculated end position, the tension member through the drill rod is introduced and firmly connected to the steel helix, the steel helix then without Rotation withdrawn by a certain amount with a tensile force applied to the tension member is, the cavity formed in front of the steel helix is pressed out with hardening building materials and the steel helix is turned back to the end position, then the drill rod removed, the The space between the tension member and the borehole wall is filled with hardening building materials and the ground anchor is prestressed after the building materials have hardened. 2. The method according to claim 1, characterized in that hardening building materials are injected only in the statically required force application area. 3. The method according to claim 1 or 2, characterized in that the cavity formed when the steel helix is withdrawn is ventilated and, after the steel helix has been brought forward again, is pressed into the end position with hardening building materials. 4. The method according to claim 1 or 2, characterized in that the retraction the cavity forming the steel helix is pressed simultaneously with hardening building materials. 5. The method according to claim 1 or 2, characterized in that the cavity is pressed with hardening building materials while the retracted steel helix is being brought forward again. 6. The method according to claim 1 or 2, characterized in that the withdrawal of the Steel helix is dispensed with after reaching the end position. 7. The method according to any one of claims 1 to 6, characterized in that the injection material Dispersions of rubber from hardening building materials are added. Considered publications:
German Patent Nos. 2,310,033, 1104,905; French Patent Nos. 435154, 619 600; "Schweizerische Bauzeitung", issue 47/1953, p. 690. 1 sheet of drawings 809 560/137 6.68 ® Bundesdruckerei Berlin