RU2221110C2 - Geological framework - Google Patents

Abstract

FIELD: construction industry, reinforcement of slopes, earthen structures of cones of bridges, viaducts, banks and beds of rivers and water ponds, reinforcement of bases of roads, airdromes, objects of industrial and civilian assignment. SUBSTANCE: geological framework of cellular structure is manufactured from flexible polymer belts put on ribs and interjoined by line welds with compression of belts by means of two clamps to form recesses in zones of welds impressed by protrusions of one clamp. Novelty of approach lies in that recesses in zones of welds have variable height diminishing towards surface of contact of belts. Height of recesses amounts to 0,55-0.75 thickness of belt. EFFECT: increased strength of weld, prolonged service life and increased strength of cellular structure under attacks of ground media. 2 cl, 4 dwg \

Description

The invention relates to construction and can be used to strengthen slopes, earthworks, cones, bridges, overpasses, slopes of coastlines and channels of water bodies, as well as for reinforcing the foundations of roads, airfields, industrial and civil construction.

A device for strengthening soils in the form of a geogrid of a cellular structure made of flexible polymer strips interconnected by welds in such a way that when tensile they form a cellular structure (see US patent No. 4717283, CL E 02 B 3/72, 1988 g.). Known technical solution has the following disadvantages. Firstly, the structural strength is not ensured due to the low strength of welds made without taking into account the optimal ratio of temperature, conditions of pressing strips and welding time. Secondly, the cell walls are solid waterproof, which violates the natural hydrological conditions and the drainage of water down the slope. The root system of plants is to some extent isolated by the outside of the cell, which complicates the conditions for the formation of a stable sod layer on the protected surface.

The closest technical solution to the invention in its essence and the achieved technical result is a cellular geo-frame made of flexible polymer tapes mounted on the ribs and connected by linear welds, when the tapes are compressed by two clamps with the formation of recesses in the weld zones from the protrusions of one from clamps (see RU 2166025, 03.21.00).

The disadvantage of this design can be attributed to the fact that the strength of the weld is about 50% of the strength of the material of the tape and at significant loads the seam breaks at the pressure points.

The problem to which the present invention is directed, is to increase the strength of the weld, as well as increase the service life and strength of the cellular structure under conditions of exposure to the soil environment.

The problem is solved due to the fact that in the geoframework of a cellular structure made of flexible polymer tapes mounted on the ribs and interconnected by linear welds when compressing the tapes with two clamps, with the formation of recesses in the weld zones from the protrusions of one of the clamps, according to the invention the recesses are made by changing the area in height, decreasing towards the contact surface of the tapes, and the height of the recesses is 0.55 - 0.75 of the thickness of the tape.

In this case, the supporting end surface of each tape can be made with alternating protrusions and depressions along the length of the tape. The recesses may be hemispherical or in the form of a truncated cone.

The technical result provided by the given set of existing features is to increase the strength of the geocarcass and the durability of its use by eliminating gaps in the weld zones both during the manufacture of the geocarcass and during installation on the surface intended to be strengthened or when used for reinforcing due to deepening in the weld zone of optimal shapes and parameters established experimentally.

The invention is illustrated by drawings, where: in FIG. 1 shows a general view of a geocarcass in an extended working condition; in FIG. 2 - general view of the geocarcass in the folded transport state; in FIG. 3 - a fragment of a tape with recesses of the weld and holes in the walls of the cells; in FIG. 4 is a section AA in FIG. 3.

The drawings indicate the following notation:

And - the length of the geocarcass in the extended (working) condition, equal to 3-12 m;

And _about - the length of the geocarcass in the folded (transport) state, equal to 0.08 - 0.32 m;

In - the width of the geocarcass in the extended (working) condition, equal to 0.5 - 3.0 m;

In _about - the width of the geocarcass in the folded (transport) state, equal to 0.7 - 4.4 m;

a = b - the width of the geocarcass cell in the extended state, equal to 0.1-1.0 m;

in _about - the width of the cell when folded, equal to the distance between the welds of 0.14 - 1.4 m;

H - the height of the geocarcass, equal to 0.05 - 0.3 m;

h is the tape thickness equal to 0.5 - 2.1 mm;

C is the width of the weld and heat-affected zones;

d $\genfrac{}{}{0ex}{}{\text{in}}{\text{from}}$ - the diameter of the recesses of the seam on top, equal to 1 - 5 mm;

d $\genfrac{}{}{0ex}{}{\text{n}}{\text{from}}$ - the size of the recesses of the seam down, equal to 0.01-4.9 mm;

t is the distance between the recesses of the seam, equal to 2-5 mm ;

d is the diameter of the perforations;

l is the distance between the perforations;

h _y - the height of the recesses of the seam 0.55 - 0.75 of h.

The geoframework consists of flexible polymer tapes 1 installed on the ribs 2 and interconnected by linear seams 3 during compression of the tapes 1 by two clamps, one of which has a flat surface and the other is made with protrusions (not shown in the drawings).

In the zones of the welds 3 during compression, recesses 4 are formed from the protrusions of one of the clamps. To eliminate the breaks of the tapes 1 both during installation and during operation of the recess 4 in the zones of the welds, a variable area is made in height, decreasing towards the contact surface 5 of the strips 1. The height of the recesses h _y is 0.55 - 0.75 of the thickness h of the tape 1. In this case, the supporting end surface 6 of the tapes 1 is made along the length of the tape 1 with alternating protrusions 7 and depressions 8.

Polymer tapes are made mainly from a mixture of high pressure polyethylene and low pressure polyethylene. Throughout the entire length of the tape 1, holes 9 are punched during the manufacturing process, which form uniform perforation over the area of the walls of the cells 10, and the size of the holes 9 is established experimentally depending on the size of the soil grains.

Light stabilizers or pigments may be incorporated into the material of the polymer tape.

In this case, the welds 3 can be located perpendicular or inclined with respect to the supporting end surface 6 of the geocarcass tapes 1, and the pressure points are formed using two clamps, one of which has a flat contact surface and the other a contact surface in the form of two or more rows staggered protrusions. The walls of the cells 10 are fastened together and with the surface being strengthened by means of connecting elements (not shown in the drawings), passed through holes 9 in the walls of the cells.

The invention is implemented by connecting polymer tapes 1 with welded linear seams 3 located in a checkerboard pattern (Fig.1, 2). To increase the strength of the structure and to increase the strength of fastening (anchoring) it on the soil surface, the geoframe can be equipped with connecting elements, for example polymer cables, passed through holes in the walls of the cells and fixed on the first and last ribbons. The number of elements is selected in accordance with the characteristics of the surface to be reinforced.

Welds have a gap zone equal to from 0.1 to 0.3 of the height of the geoframe. When the geocarcass is stretched to the operating state, the weld gap zones open, forming slotted holes, which improves drainage conditions and the communication of the cavities of adjacent cells.

The holes 9 in the walls of the cells 10 are evenly distributed over the area of the walls. In any vertical section of the cell wall outside the weld zone, the sum of the size of the holes should be no more than 30% of its height. When this condition is met, the tensile strength of the tape along the line of holes will be approximately equal to the strength of the weakest element of the geoframe, namely, the strength of the weld, which meets the criterion of equal strength design.

In the manufacture of geo-frames to strengthen clay and sandy soils at facilities where hydrological conditions do not affect its functioning, for example, in areas with an arid climate, it is advisable to carry out structures from non-perforated polymer tapes.

The surface of the welded tapes can be smooth or embossed to increase the coefficient of adhesion of the soil material to the cell walls.

Tapes 1 (Fig.1, 2) are welded together by introducing a hot solid wedge into the contact zone of welding to obtain a viscoplastic state. Then the wedge is removed from the welding zone and the tapes are compressed using two clamps. One clamp has a flat contact surface, and the other a contact surface in the form of two or more rows of protrusions (not shown in the drawings).

According to the invention, the recesses formed in the weld zones have a curved shape without straight and sharp angles, for example, predominantly hemispherical or truncated cone shape.

The strength of the resulting weld is more than 56% of the strength of the original tape, which exceeds the same indicator of the known solution by 10-12%.

When performing reinforcing work, the geo-frame is stretched into working condition and installed on a previously prepared soil surface. Then the geoframe is fixed on the reinforced layer by means of anchors (not shown in the drawings). In a similar way, next to the first geocarcasses are installed close to the first, connecting them with each other and with the lower layer by L-shaped anchors (not shown in the drawings). After that, soil material, gravel, gravel, a sand-gravel mixture or concrete are laid in the cells, depending on the purpose of the object.

Soil material - the cell aggregate accepts compressive loads, and the cell walls perceive tensile (shear) stresses. External loads are distributed evenly over the surface to be strengthened due to the communication between the cell cavities, anchoring and additional connecting elements. The optimal location on the cell walls of the perforations ensures reliable drainage of the reinforced soil layer.

Claims (3)

1. Geoframework of a cellular structure made of flexible polymer tapes mounted on the ribs and interconnected by linear welds when compressing the tapes with two clamps to form depressions in the weld zones from the protrusions of one of the clamps, characterized in that the recesses in the weld zones are made variable area in height, decreasing towards the contact surface of the tapes, and the height of the recesses is 0.55-0.75 thickness of the tape. 2. Geoframework according to claim 1, characterized in that the supporting end surface of the tapes is made along the length of the tape with alternating protrusions and depressions. 3. Geoframework according to any one of claims 1 and 2, characterized in that the recesses are hemispherical or in the form of a truncated cone.

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