RU1789719C - Method for installation of anchor - Google Patents

Abstract

The invention relates to mining. The goal is to increase the bearing capacity of the anchor. To do this, a load-bearing rod (HS) with a head and a retaining element (PE) is introduced into the drilled well (C). Then, C is filled with bulk material, the HS is vibrated and pressed in by tensioning it to efforts exceeding the design ones. The press-in of the HS is carried out along the length C in parts, cyclically. In each cycle, at the same time as the bulk material, granular plastic filler 2 carrier is introduced into C in a volume equal to the volume of the pore space of the bulk material. When pressing in simultaneously with the tension of the HS, the PE is crushed inside C with a force equal to the force of the tension of the HS. At the end of each cycle, PE is recovered. The crushing force can be applied to the retaining element by means of tubular rods. The latter are put on the HS to the end in PE and moved along it by tightening the nut on the threaded end. A hydraulic device may be used to press in the HS. Moreover, C can be filled with a mixture of granular material and cement mortar in a state of loss of fluidity, but before setting. As a plastic material, raw clay granules with a grain size of up to 0.2 mm can be used. After installation, the anchor is immediately put into operation. An increase in the bearing capacity of the anchor is achieved due to a more uniform distribution of stresses in its lock. 4 c.p., 4 ill. (L C

Description

The invention relates to the mining industry, namely, anchoring of mine workings and can be used in the construction of anchors in construction.

A known method of erection of anchor support, including drilling a hole, introducing into it a load-bearing rod with supporting and retaining elements, filling the hole with bulk material, the threshold space of which is filled with frozen water, its compaction, tension

the rod (USSR AS No. 1373828 E 21 D 21/00, publ. VBI No. 6, 1988).

The known method is applicable in the construction of pliable supports and a relatively low bearing capacity is achieved with a limited length of the anchor lock, due to a decrease in friction forces from the presence of water in the zone of contact with the bullet material with the borehole walls and insufficiently dense packing of the material.

Known technical solution - anchor cartridges Semicron 2000 company

Xi 00

U VI

Yu

Commercial plastics spectral product ltd.), Great Britain (Modern constructions of anchor support and equipment for its installation used in foreign mines. Serial mining. Central Research Institute of Engineering and Technology of Black Metallurgy. Issue 1.M, 1988, p. 9) according to which together with Wax microcapsules with water representing a plastic material are introduced by a load-carrying rod and bulk materials.

In the known solution, the capsules serve to accommodate water and, at the same time, cannot be placed during compaction of the bulk material in its pore space, which negatively affects the strength of the anchor lock, in addition, the lack of tension of the anchor to realize external friction and dilatancy properties of the bulk material. as well as the presence of a cartridge shell significantly reduces the bearing capacity of such an anchor.

The closest analogue (prototypic O is a method of constructing an anchor support, including drilling a well, introducing a load-bearing rod and a retaining element, filling the well with bulk material when exposed to vibration at a depth of H, tensioning the rod to forces exceeding design ones (A.S. USSR No. 1046531 E 21 D 21/00, published in BI No. 37, 1983).

The disadvantage of this method is the limitation of the bearing capacity of the anchor by the destruction of the grains of the granular material due to high contact stresses under the head of the anchor, uneven raining of stresses and deformations in the bulk material, as well as the need to fix and leave a retaining element in the well in order to prevent decompression of the bulk material.

The aim of the invention is to increase the bearing capacity of the anchor. This goal is achieved in that in a method of erecting an anchor support, including drilling a well, introducing into it a load-bearing rod with a head and a retaining element, filling the well with bulk material, vibrating and pressing the rod by tensioning it to forces exceeding the design, according to the invention, filling wells and the press-in of the core is carried out cyclically along the length of the well in part, while in each cycle simultaneously with bulk material a granular porous plastic filler is introduced into the well th space in volume equal to the volume of pore space of bulk material, and

when pressing in, simultaneously with the tension of the rod, the retaining element is pressed into the well with a force equal to the tension of the rod, and at the end of each cycle, the retaining element is removed. Another difference of the proposed method is that a crushing force is applied to the retaining element by means of tubular rods that are worn

0

on the rod all the way into the retaining element.

Another difference of the proposed method is that a hydraulic spacer is used to press the rod in. An additional difference of the proposed method is that a mixture of granular material with cement mortar is used in a state of loss of fluidity, but before setting. Another additional difference offered

0 of the process is that raw clay granules with a grain size of up to 0.2 mm are used as a plastic material.

The figure shows the anchor at the time of installation (Fig. 1) with the application of the plot

5 radial stresses ag along the length of the anchor lock (ibid.); an anchor at the time of complete formation of the anchor lock along the entire length of the well (Fig. 2); example of tensioning the rod and pressing

0 of the anchor lock by means of a nut on its threaded part protruding from the well through intermediate tubular rods (Fig. 3) and the same using a hydraulic spacer (Fig. 4).

5 The construction of anchor support is carried out as follows. A load-bearing rod 2 is introduced into the pre-drilled well 1, having a head 3 on its side. Then, well 1 is filled to the required depth H with a mixture of granular material 4 and plastic material 5 when compacted with a vibrator (not shown in the drawing), a retaining element 6 is introduced, and the stern 5 Жн 2 is tensioned and the mixture of materials 4 and 5 is pressed into well 1 through a retaining element 6 with a force P exceeding the design bearing capacity of the anchor (Fig. 10). Moreover, unlike the prototype, the peaks of the maximum

0

the radial stresses ar on the walls of the well 1 will be observed from two sides, from the side of the head 3 of the anchor and the retaining element 6 (see diagram). It means that

t- ceteris paribus x can be achieved approximately two times greater load-bearing capacity compared with the known technical solution. The formula for determining the required depth of filling of the well H with bulk material 4 when filling its first space with plastic material 5 remains valid since determines the depth of distribution of dilatancy processes when it is loaded. That is, the filling depth is determined by the formula

II F, „lnrfSfn) 2-s fn) 2x М -Sfn-S f riLYF.

X (0.1Po + s)

where H is the depth of filling the well with bulk material, cm;

F is the annular cross-sectional area formed by the load-bearing rod and the walls of the well, cm sq;

S is the perimeter of the cross section of the well, see

S is the perimeter of the cross section of the load-bearing rod, cm;

f is the coefficient of friction between the bulk material and the wall of the well;

f is the coefficient of friction between the bulk material and the load-bearing rod;

p is the coefficient of lateral thrust;

Y is the bulk density of bulk material, g / cm3,

Ro - design bearing capacity of anchor support, kN.

After the completion of the press-in cycle, the retaining element 6 is removed from the well 1 and again filled with loose 4 and plastic 5 materials, when exposed to vibration to a depth H, the rod 2 is again tensioned and the materials 4 and 5 are pressed into the well 1 through the retaining element 6 with a force P exceeding the design load on the anchor. The operations are repeated until the anchor lock is formed along the entire length of the well 1 (see Fig. 2), which makes it possible to further increase the bearing capacity of the anchor. It should be noted that, in the load-carrying rod 2, the pre-tensioning force is retained even after the tensioning force P is removed, and in the materials 4 and 5, respectively, the pressing-in force.

The most simply claimed method is realized by means of a tubular rod 7, which, when the nut 8 is tightened with a wrench (not shown) on the threaded part 9 of the anchor protruding from the borehole 1, allows simultaneously creating a pulling force P of the rod 2 and an equal pressing force materials 4 and 5 (see. Fig. 3).

For mechanization of the technological process, a hydraulic spacer 10 is used, connected directly to the threaded part 9 of the anchor and acting through the rod 7 on the retaining element 6 (see Fig. 4).

The invention is illustrated by the following examples.

PRI me R 1. Hard cement mortar C: P 1: 2.5 grade 100, B: C 0.32 was fed into a pre-drilled hole with a diameter of 43 mm; after vibration and compaction with a VP-1 vibrator with a frequency of 50 Hz, the rod was tensioned and, often, the solution was pressed in cycles with a force of P 10 tons, as shown in FIG. 3, through high-strength steel pipe

and retaining element. The tension was controlled by a dynamometer. Immediately after the installation of the rod, it was pulled out. The bearing capacity of the anchor was 12 tons.

PRI me R 2. A mixture of sand from rounded grains with a compressive strength of 150 MPa and a particle size of 0.2-0.5 mm granules of raw clay with a grain size of 0.2 mm was placed in a hole with a diameter of 43 mm together with a core of

steel 3 having a head in the castle part and a thread M 20 at the end protruding from the hole. After pressing the mixture of materials in parts, it is cyclic in the borehole with a force of 7.5 tons, with an anchor tension of up to 10

there is no loss of anchor bearing capacity, up to a thread failure on the shaft.

When using the claimed method of erection of anchor support is achieved

following positive effect:

- lining comes under load immediately after installing the anchor;

- an increase in the bearing capacity of the anchor is achieved due to a more uniform distribution of stresses in the lock of the anchor also in connection with the possibility of an additional increase in the length of the anchor lock;

- the use of relatively cheap materials and a reduction in their consumption in a number of cases makes it possible to reduce the cost of lining with an increase in its bearing capacity.

- lining has the advantages of prestressed anchors.

Claims (5)

1. A method of erecting an anchor, including drilling a well, introducing into it a load-bearing rod with a head and a retaining element, filling the well with bulk material, vibrating and pressing the rod by means of its voltage to exceed design forces, characterized in that, in order to increase the bearing capacity of the anchor, the filling of the wells and the pressing of the rod is carried out cyclically along the length of the well, in this case, in each cycle, simultaneously with bulk material, a granular plastic filler is introduced into the well the volume equal to the volume of the feather space of the bulk material, and when pressing in simultaneously with the tension of the rod, the retaining element is pressed inside the well tension with a force equal to the tension force of the rod, and at the end of each cycle, the retaining element is removed. 2. A method according to claim 1, characterized in that a crushing force is applied to the retaining element by means of tubular rods which are put on the rod all the way into the retaining element. 3. The method according to claim 1, characterized in that a hydraulic spacer is used to press the rod in. 4. The method according to PP. 1-3, characterized in that the well is filled with a mixture of granular material and cement mortar in a state of loss of fluidity, but before the start of setting. 5. The method according to PP. 1-3, characterized in that as the plastic material is used granules of raw clay with a particle size of up to 0.2 mm Phage 2 Fig.Z