RU2131495C1 - Method of constructing ground anchor and ground anchor itself - Google Patents

Abstract

FIELD: construction, in particular, construction of buried structures and fixing of slopes. SUBSTANCE: method includes driving of casing with lost shoe to design depth, installation of reinforcement tie inside casing, knocking-out of lost shoe, interval injection of cement mortar to zone of embedding of anchor through casing as it is retrieved, full retrieving of casing with filling of hole with cement mortar. Additionally lowered into casing sunk to design elevation is energy radiator used for driving-out of lost shoe. Then casing is filled with hardening material and casing lower end is hoisted to elevation of beginning of anchor embedding. Radiator position is fixed 1.0-2.0 diameters below casing end. Further on, well walls are treated with electrical discharges of radiator into hardening material with moving of radiator together with casing along length of lining to form lining with continuous supply of additional amount of hardening material into casing. Upon completion of lining formation, radiator is retrieved and reinforcement tie is lowered into casing, and then casing is fully retrieved. EFFECT: increased bearing capacity of pile and durability of anchors. 9 cl, 12 dwg

Description

 The invention relates to geotechnical construction and for the construction of buried structures in the strengthening of slopes.

 There is a method of erecting an anchor pile, including immersing a hollow anchor to the design depth, installing a rotary rod with pyro charges in its plane, after which explosives are blasted and the anchor strips are moved in the form of plates along cylinders (see ed. St. USSR N 761663, class 5 E 02 D 5/54).

 Known anchor pile, including a shell, in the walls of which flush cylinders are fastened with strikers, and at the ends of the cylinders hollow bushings are fixed coaxially in height, in which a rotary rod with pyro charges is installed (see ed. St. USSR N 761663, class 5 E 02 D 5/54).

 There is a method of erecting a ground anchor, including immersion of casing pipes with a lost shoe at the design depth, installation of reinforcing rods inside the casing pipes and knocking out of the lost shoe with it, interval pumping of cement mortar into the anchor filling zone through the casing pipes as they are removed, and the casing pipes are completely removed from filling the well with cement mortar (see, for example, M.I.Smorodinov "Anchoring devices in construction", M., Stroyizdat, 1983, p. 103).

 A well-known soil anchor, including termination and reinforcing rod (see ibid., P. 103).

 A disadvantage of the known technical solution is the low bearing capacity of the soil anchor and its fragility. The low bearing capacity, especially in dense clay soils, is explained by the cylindrical shape of the anchor seal obtained during drilling, which can hardly be changed when injected with static pressure. An increase in pressure leads to ruptures in the soil and uncontrolled withdrawal of the injection solution. The fragility of the anchors is caused by the creep and fracture of the cement stone of the embedment and, as a result, by corrosion of the reinforcement.

 The essence of the claimed invention is expressed in the aggregate of essential features sufficient to achieve the technical result provided by the invention, which consists in increasing the bearing capacity of the pile and the durability of the anchors.

 The proposed technical solution is characterized by the fact that an energy emitter is lowered into casing pipes immersed up to the design mark, with the aid of which the lost shoe is knocked out, the pipes are filled with hardening material and raised to the mark of the beginning of anchor embedment, the position of the emitter is fixed 1.0-2.0 times lower of its end, then they begin to process the walls of the well, producing electric discharges of the emitter in the hardening material (for example, fine-grained concrete), moving the emitter with the casing along the length of the seal, and forms comfort sealing, continuously supplying an additional amount of hardening material to the casing; after the termination molding is completed, the emitter is removed, and the anchor rod is lowered into the casing, and then the casing is completely removed.

 The claimed combination of essential features is in direct causal relationship to the achieved result.

 Analysis and comparison of distinctive features.

 n. A known method of forms. p. 1. Sequence of operations: immersion of casing pipes with a shoe.

 The proposed method. Immersion of casing with a shoe, lowering of the energy emitter.

 The known method. Lowering of reinforcing rods, interval injection of cement slurry as casing pipes are removed (including the pressure on the length of the seal, the pressure on the free length).

 The proposed method. Filling pipes with cement mortar, removing casing pipes to the length of the seal, interval as the casing is re-immersed, electro-hydraulic molding of the anchor seal, lowering the reinforcing rod, removing the casing pipes.

 The known method. p. 1. Anchoring is performed from cement mortar.

 The proposed method. The sealing is made of fine-grained concrete.

 The known method. p. 1. The thrust is freely placed in the well.

 The proposed method. The rod is fixed in a lost shoe, for example on a thread.

 The known method. p. 2, 3, 6. The sealing is made of a cylindrical shape.

 The proposed method. The embedment is made of a conical, biconical or polyspherical shape, including with different diameters of spheres.

 The known method. p. 8. The thrust is made in the form of a single rod.

 The proposed method. The thrust is made in the form of additional elastic rods welded to the central one.

 The known method. p. 4. Traction insulation is made of a plastic pipe with anti-corrosion grease.

 The proposed method. Traction insulation is made discretely from cement stone, in between - from a plastic or rubber ring, which simultaneously performs the function of a deformation concentrator.

 The known method. p. 9. Anchor has a head part and a seal.

 The proposed method. Anchor has two fixings.

 Comparison of the claimed technical solution with the prototype made it possible to establish its compliance with the novelty criterion, since the claimed solution is not known from the prior art.

 The proposed method of erecting a soil anchor and soil anchor are industrially applicable using existing technical means and meet the criterion of "inventive step", since they do not explicitly follow from the prior art, while the latter does not reveal the essential characteristics prescribed for the conversion necessary to achieve the specified technical result.

 Thus, the proposed technical solution meets the criteria of the invention.

 The other known technical solutions for a similar purpose with similar significant features by the applicant was not found.

 The invention is illustrated by drawings, where in FIG. 1 shows well drilling; FIG. 2 shows the release of the casing from the shoe; FIG. Figure 3 shows the removal of the pipe to the estimated termination length while filling the cavity with injection solution and the emitter on the rod in the calculated position; FIG. 4 shows the electrodynamic treatment of a well filled with a solution as the emitter and casing are immersed before the bottom; in FIG. 5 shows a finished anchor with a reinforcing rod and an insulating sheath, FIG. 6 shows an anchor with polyspherical embedment; FIG. 7 shows an anchor with a conical shape of the embedment; FIG. 8 shows an anchor with a biconical embedment shape; FIG. 9-10 show reinforcing rods with strain concentrators, in FIG. 11 shows an anchor with a helical surface along its entire length; FIG. 12 shows anchors with terminations at both ends.

The described method is implemented as follows:
A well-known drilling rig, for example, a Bauer machine tool 1, drills an inclined well 2 under a temporary soil anchor 3. Drilling is carried out by driving, crushing, or screwing the casing 4 with the shoe 5 to the design depth. Then, a hardening mortar 6 (for example, cement slurry) is poured into the casing 4, then a source of electric discharges, for example, a pulsed emitter 7, is lowered on the rods 8, connected to the discharge station 9 by a cable 10. The emitter 7 rests against the lost shoe 5 and they achieve its disconnection when lifting the casing 4 to a length of 0.2-0.5 m. Then, the casing 4 together with the emitter 7 is removed from the well 2 by the length of the embedment 11 of the future anchor 3, and the released cavity 2 is filled with a hardening solution 6, the calculation is fixed the position of the emitter 7 relative to the casing 4 (0.2-0.4 m or 1.0-2.0 d) and begin the electrodynamic processing (ED) of the well 2 with the interval or continuous movement of the casing 4 to the bottom of the well 2. as the EDM is implemented, the walls of the well 2 are moved apart, the volume of the cavity increases several times, and the hardening solution 6 continuously flows down the casing 4, filling the cavity of the seal 14 of the anchor 3. As the casing 4 moves, the casing 4 overlaps the formed sections of the walls of the well 2, protecting them from the influence water hammer production carried in solution by electric discharges.

 When the emitter 7 reaches the bottom of the well 2, the EDI is stopped, the emitter 7 is removed from the casing 4, and the rod 12 of the anchor 3 is lowered into the pipes 4 in the form of a rod, rope, with a support pipe, etc. After installing the rod 12 with a protective sheath 13, the casing 4 is removed from the well 2. Anchor 3 is ready for testing after curing of the hardening material 6 of the seal 11.

 There are various ways to implement the proposed method.

 Given that in most types of soil there is no injection of a pure cement mortar directly into the pores of the soil, there is no need to use this short-lived material as an anchor material. In the proposed method, fine-grained concrete can be used as a hardening material (according to the classification SNiP 2.03.01-84; Concrete and reinforced concrete structures with cement-sand composition = 1: (1-3), as more durable and durable).

 The lost shoe 5 can be made with a screw coupling 17 or other device for fixing the reinforcing rod 12. In this case, the shoe 5 acts as the heel of the rod 12 and serves to transfer force from the rod 12 to the concrete body of the seal 11. For this, an additional fixation operation is assumed end of traction. Lost shoe 5 can be made in the form of a screw with a larger diameter than the casing, which allows to obtain a helical surface of the anchor 3 when screwing the casing 4.

 Of particular importance is the form of embedment 11 of anchor 3. Known structures transmit the load to the ground, mainly by friction on the side surface of the embedment. With incompressible soils, the form of embedment is cylindrical, and the bearing capacity of anchor 3 is very small.

 In the proposed design, the seal 11 of the anchor 3 is made of a conical 14 or polyspherical 15 shape. Conical seal 14 with an angle at the apex of 2-6 degrees. (for clays) or (1 / 8-1 / 4) β for sands, where β is the angle of internal friction allows to transmit the force from the rod 12 in the radial direction due to the pressure. The bearing capacity of the conical 14 anchor is 1.8-2.5 times higher than the cylindrical same volume (Fig. 7-8).

 The biconical form 14 allows evenly transmit compressive stresses from the shoe 5 to the concrete body of the anchor 11, compressed from the opposite side of the soil pressure. The bearing capacity of conical anchors increases when they are sent to the structure.

 In weakly compressible soils it is very effective to use polyspherical anchors 16 (Fig. 6). In this case, the diameters of the spheres can be different, including changing according to a linear law with an increase towards the end of the embedding.

 The strain concentrators 19 weaken the tensile strength of the concrete section and initiate the opening of cracks 21 in a given sheet. Deformation concentrators 19 are rings or half rings with or without collars 20, worn on a reinforcing bar or rope at a distance of 1-3 d of concrete section. Material of hubs 19: rubber, plastic, etc. has greater tensile properties than concrete and is waterproof, which provides reliable crack closure 21.

 Sometimes it is advisable not to fulfill the enclosing wall, but instead to arrange anchors with terminations on both sides (Fig. 12).

 When erecting anchors with a small angle to the horizontal, it is advisable to perform electrodynamic processing of the embedment under excessive pressure of the hardening material.

Claims (9)

 1. A method of erecting a ground anchor, including immersing a casing pipe with a lost shoe at a design depth, installing reinforcing rods inside the casing pipe, knocking out a lost shoe, injecting cement mortar into the anchor filling zone through the casing pipe as it is removed, completely removing the casing pipe from filling the well with cement mortar, characterized in that an energy emitter is additionally lowered into the casing submerged to the design mark, with which the lost ashmak, fill the pipe with hardening material and raise its lower end to the mark of the beginning of embedment of the anchor, fix the position of the emitter 1.0-2.0 diameters below its end, then begin to process the walls of the well, producing electrical discharges with the emitter in the hardening material (for example, fine-grained concrete) by moving the emitter with the casing along the length of the embedment, and form the embedment, continuously supplying an additional amount of hardening material to the casing, after the end of the formation of the embedment, the emitter is removed, and bsadnuyu reinforcing rod pipe is lowered, and then completely removed the casing. 2. The method according to claim 1, characterized in that the termination is performed in the form of a cone with an angle at the apex from 2 to 6 ^o . 3. The method according to claim 1, characterized in that the sealing is biconical, while at the top of a small cone with an angle of 42-50 ^{o there} is a lost shoe equipped with a clutch for fixing traction.  4. The method according to p. 1 or 2, characterized in that the traction is performed with concentrators of deformation of concrete at a distance of 1-3 diameters of the concrete section of the seal from each other.  5. The method according to any one of claims 1, 4, characterized in that the casing is immersed by screwing in the lost shoe, thereby forming a profiled surface of the anchor.  6. The method according to p. 1, characterized in that the termination is performed in a polyspherical shape with an increase in the diameter of the spheres from the beginning of the termination to the end.  7. The method according to any one of claims 1 to 6, characterized in that the supply of an additional amount of hardening material during processing of the walls of the borehole is done at an overpressure of 1.2-2 times more than the domestic one.  8. Soil anchor, including termination and reinforcing rod, characterized in that the rod is made in the form of a Central rod and elastically attached peripheral elements.  9. The soil anchor of claim 8, characterized in that it has terminations at both ends.

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