Flexible barrier and designing method thereof

Abstract

A flexible barrier includes: posts, retaining ropes and a metal net; wherein each of the posts comprises a post body and a post foundation hinged; the retaining ropes includes longitudinal retaining ropes, top retaining ropes, intermediate retaining ropes, and diagonal retaining ropes connected between the posts and the metal net; wherein a lower portion of the metal net is obliquely arranged towards a downstream of a slope; the metal net is loose when no impact is applied and a bottom of the metal net is fixed with short anchors; the bottom of the metal net has a redundancy and is folded towards a upstream of the slope or buried in the slope.

Claims

1. A flexible barrier, comprising: a plurality of posts, wherein each of the posts comprises a post body and a post foundation hinged to a bottom end of the post body; a metal net, wherein a lower portion of the metal net is obliquely arranged towards a downstream of a slope; the metal net is loose when no impact is applied and a bottom of the metal net is fixed with short anchors; the bottom of the metal net has a redundancy and is folded towards a upstream of the slope or buried in the slope; and a plurality of retaining ropes, wherein the retaining ropes are connected between the posts, comprising: longitudinal retaining ropes connected between tops and bottoms of the posts, top retaining ropes which are latitudinally extended and connected between the tops of the posts, intermediate retaining ropes latitudinally running through the whole metal net, and diagonal retaining ropes diagonally running through the whole metal net; wherein an upper portion of the metal net is connected to the top retaining ropes while a middle portion of the metal net is connected to the intermediate retaining ropes.

2. The flexible barrier, as recited in claim 1, wherein the intermediate retaining ropes latitudinally runs through the whole metal net and are anchored to two side slope surfaces; first ends of the longitudinal retaining ropes are connected to the tops of the posts; second ends of the longitudinal retaining ropes pass through the metal net which is obliquely arranged towards the downstream of the slope and reach the bottom of the metal net, and then moves upwards along a slope surface to reach the post foundation of same posts.

3. The flexible barrier, as recited in claim 1, wherein top ends of the diagonal retaining ropes are connected to the tops of the posts; bottom ends of the diagonal retaining ropes pass through the bottom of the metal net which is obliquely arranged towards the downstream of the slope, and then moves upwards to reach the post foundation of adjacent posts.

4. The flexible barrier, as recited in claim 1, wherein the lower portion of the metal net is obliquely arranged towards the downstream of the slope, which forms an angle of 0-60 degrees with a horizontal plane.

5. The flexible barrier, as recited in claim 1, wherein the posts comprise at least two border posts and intermediate posts between the border posts; for ensuring balance of the posts, tops of the border posts and the intermediate posts are connected to anchor ropes which are oblique towards the upstream of the slope.

6. The flexible barrier, as recited in claim 5, wherein energy dissipating devices are connected to top ends of the longitudinal retaining ropes, the diagonal retaining ropes and the anchor ropes as well as both ends of the top retaining ropes and the intermediate retaining ropes, so as to buffer an impulse load of an impact and provide a larger flexible deformation.

7. The flexible barrier, as recited in claim 5, wherein the top retaining ropes are tensioned by the border posts and the intermediate posts.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a top plane view of a flexible barrier of the present invention;

(2) FIG. 2 is a side view of the flexible barrier of the present invention;

(3) FIG. 3 illustrates the flexible barrier of the present invention when being impacted by loose soil mass;

(4) FIG. 4 illustrates force analysis of the loose soil mass;

(5) FIG. 5 illustrates force analysis of a longitudinal retaining rope of the flexible barrier of the present invention; and

(6) FIG. 6 is a top plane view of the flexible barrier according to another embodiment of the present invention.

(7) Referring to FIGS. 4 and 5, P is the pressure applied on the soil mass by the flexible barrier, G is a gravity force of the soil mass, N is a support force applied on the soil mass by the slope surface, ƒ is a friction resistance between the slope surface and the soil mass, ψ is an angle between the slope surface and a surface of the soil mass, and θ is an angle between the slope surface and a horizontal plane, F is the impact force applied on the flexible barrier by the soil mass, and T is the internal force of the longitudinal retaining ropes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(8) Referring to the drawings and embodiments, the present invention will be further illustrated.

(9) Referring to FIG. 1, a flexible barrier of the present invention comprises: a plurality of posts 1, a plurality of retaining ropes 2, a metal net 3, anchor ropes 4, energy dissipating devices 5 and short anchors 6.

(10) The posts 1 comprise two border posts 11 and intermediate posts 12 between the border posts 11; for ensuring balance of the posts 1, tops of the border posts 11 and the intermediate posts 12 are connected to the anchor ropes 4 which are oblique towards the upstream of the slope. Each of the posts 1, namely the border posts 11 and the intermediate posts 12, comprises a post body and a post foundation hinged to a bottom end of the post body.

(11) The retaining ropes 2 are connected between the posts 1, comprising longitudinal retaining ropes 20 connected between tops and bottoms of the posts 1, top retaining ropes 21 which are latitudinally extended and connected between the tops of the posts 1, intermediate retaining ropes 22 latitudinally running through the whole metal net 3, and diagonal retaining ropes 23 diagonally running through the whole metal net 3; wherein the top retaining ropes 21 are tensioned by the border posts 11 and the intermediate posts 12. The intermediate retaining ropes 22 latitudinally runs through the whole metal net 3 and are anchored to two side slope surfaces; two diagonal retaining ropes 23 are connected between each adjacent posts 1, wherein the diagonal retaining ropes 23 and the intermediate ropes 22 are not essential and can be modified according to a slope angle and a scale of loose soil mass. First ends of the longitudinal retaining ropes 20 are connected to the tops of the border posts 11 (or intermediate posts 12) of the posts 1; second ends of the longitudinal retaining ropes 20 pass through the metal net 3 which is obliquely arranged towards the downstream of the slope and reach the bottom of the metal net 3, and then moves upwards along a slope surface to reach the post foundation of the same border posts 11 (or intermediate posts 12). Top ends of the two diagonal retaining ropes 23 between each adjacent posts 1 are connected to the tops of the adjacent posts 1; bottom ends of the diagonal retaining ropes 23 pass through the bottom of the metal net 3 which is obliquely arranged towards the downstream of the slope, and then moves upwards to respectively reach the post foundation of adjacent posts 1, which means the two diagonal retaining ropes 23 of an interval intersect and pass through the bottom of the metal net 3, and then are connected to the post foundation of the adjacent posts 1.

(12) Referring to FIG. 2, an upper portion of the metal net 3 is connected to the top retaining ropes 21 of the retaining ropes 2 while a middle portion of the metal net 3 is to connected to the intermediate retaining ropes 22, wherein the lower portion of the metal net is obliquely arranged towards the downstream of the slope, which forms an angle of 0-60 degrees with a horizontal plane, and the angle can be adjust according to the slope angle. The metal net 3 is loose when no impact is applied and a bottom of the metal net 3 is fixed with the short anchors 6; the bottom of the metal net 3 has a redundancy and is folded towards an upstream of the slope or buried in the slope.

(13) The energy dissipating devices 5 are connected to top ends of the longitudinal retaining ropes 20, the diagonal retaining ropes 23 and the anchor ropes 4 as well as both ends of the top retaining ropes 21 and the intermediate retaining ropes 22, so as to buffer an impulse load of an impact and provide a larger flexible deformation; wherein the energy dissipating devices 5 can be arranged with different quantities, positions and forms according to actual requirements.

(14) Referring to FIG. 3, the flexible barrier of the present invention is under a tension state after being impacted, and the loose soil mass 7 in the impact process is constrained by the flexible barrier, wherein force analysis thereof is shown in FIG. 4. The subsequent moving loose soil mass 8 directly impacts the loose soil mass 7 instead of the flexible barrier itself.

(15) Referring to FIG. 5, the impact force F applied on the flexible barrier by the longitudinal retaining ropes 20, a gravity force G of the soil mass and an internal force T of the longitudinal retaining ropes 20 are balanced.

(16) The main difference between the flexible barriers shown in FIG. 6 and FIG. 1 is that the applied terrain conditions are different. The flexible barrier shown in FIG. 1 is mainly applicable to hill-slope debris flow and granular avalanche, which means the loose soil body moves downwards along the flat slope, and the barrier can extend indefinitely in the width direction. However, the flexible barrier shown in FIG. 6 is mainly applicable to channelized debris flow and granular avalanche, which means two sides of to the loose soil mass moving downwards are constrained within a U-shape channel. The specific implementation is as follows: the border posts 11 are replaced by up-down arranged anchors 13 which are anchored on two side walls of the U-shape channel, and the intermediate posts 12 can be omitted if a width of the U-shaped channel is relatively small; the metal net 3 is converged from two sides of the barrier to the up-down arranged anchors 13, and is generally pocket-like; the intermediate retaining ropes 22 are no longer directly anchored on the slope surface, but is directly connected to the anchors 13.

(17) A designing method or principle of the flexible barrier comprises steps of:

(18) (1) as a frictional material, calculating a stress (pressure)-dependent shear strength of soil mass as:
τ=c+μσ  (1)

(19) wherein in the equation (1), τ is the shear strength of the soil mass, c is a cohesion of the soil mass, μ is a coefficient of friction of the soil mass, and σ is a normal stress of the soil mass;

(20) (2) maintaining a small angle between the flexible barrier and a slope surface; linearly improving a shear resistance at unit width of the flexible barrier through a pressure P applied on the soil mass by the flexible barrier (force analysis is shown in FIGS. 3 and 4); when:
ƒ<c+μN=c+μ(P cos ψ+G cos θ)  (2)

(21) moving soil mass tends to be stopped and static soil mass is still; in the equation (2), ƒ is a friction resistance between the slope surface and the soil mass, N is a support force applied on the soil mass by the slope surface, P is the pressure applied on the soil mass by the flexible barrier, G is a gravity force of the soil mass, ψ is an angle between the slope surface and a surface of the soil mass, and θ is an angle between the slope surface and a horizontal plane; friction between the flexible barrier and the soil mass is ignored and cohesion c of the soil mass is generally negligible; and

(22) (3) maintaining the small angle between the flexible barrier and the slope surface for improving an internal force T of longitudinal retaining ropes of the flexible barrier (force analysis is shown in FIG. 5), wherein a relationship between the internal force T of the longitudinal retaining ropes of the flexible barrier and an impact force of the moving soil mass is:
T=F/cos(ψ+θ)  (3)

(23) wherein in the equation (3), T is the internal force of the longitudinal retaining ropes, F is the impact force applied on the flexible barrier by the soil mass; when an angle ψ+θ between the flexible barrier and the slope surface is nearly perpendicular, the internal force T of the longitudinal ropes tends to be infinite; wherein the internal force T of the longitudinal retaining ropes decreases when the angle ψ between the slope surface and the surface of the soil mass decreases; when the longitudinal retaining ropes are omitted, an internal force of the metal net tends to be infinite.

(24) The structure design of the present invention is simple and reasonable, and can fully take advantage of the strength of the loose soil mass to block the movement thereof and systematically reduce the internal force of the structure, which effectively overcomes problems that the conventional flexible barrier cannot fully utilize the strength of the loose soil mass and overall internal force of the flexible barrier is too high under impact.

(25) One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

(26) It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.