Rockfall pre-sensing active avoiding type steel column supporting system

Abstract

The present invention relates to the technical field of slope rockfall protection, and provides a rockfall pre-sensing active avoiding type steel column supporting system which comprises a rotatable column foot, a deflection steel column, a pulley node, a pre-sensing upper pulling anchor rope and a connecting piece. A bottom lug plate of the deflection steel column is provided with a hole, the fit tolerance of a diameter of the hole and a diameter of a pin shaft is large, so as to help the steel column to rotate in a horizontal direction. The pulley node is provided with double pulleys, a pre-sensing pull-up anchor rope is wound on each of the two pulleys, two anchor points of each rope are distributed on two sides of a projection line (hereinafter referred to as the projection line) of an initial axis of the steel column on a slope surface, one anchor point is near the projection line, and the other anchor point is far away from the projection line. Before falling rocks impact the steel column, the pull-up anchor rope on one side near the projection line is firstly impacted, and the steel column deflects towards the other side under the action of a resultant force of the pull-up anchor rope, so that falling rock impact can be avoided or impact damage of the steel column can be reduced. The protection problem that falling rocks directly impact the steel columns is solved, and the impact resistance reliability and disaster prevention toughness of the passive nets are greatly improved.

Description

ROCKFALL PRE-SENSING ACTIVE AVOIDING TYPE STEEL COLUMN SUPPORTING SYSTEMTECHNICAL FIELD

[0001] The present invention relates to the technical field of slope rockfall protection, and provides a rockfall pre-sensing active avoiding type steel column supporting system, which is adapted to address the anti-collision issues of steel columns in passive flexible protection net systems, and can significantly improve the impact resistance reliability and disaster prevention toughness of passive nets.BACKGROUND

[0002] Rockfall disasters are common geological hazards in mountainous areas of China. Characterized by suddenness, randomness, severe destructiveness and etc., they pose significant hidden threats to people’s life and property. In China, flexible protection structures serve as critical technical equipment for preventing and mitigating rockfall disaster losses. As a key component of flexible protection net systems, passive flexible protection net systems can effectively intercept falling rocks, and reduce the impact of rockfall on safety of people’s life and property and normal operation of roads.

[0003] However, there are still the following problems:

[0004] Upon designing passive flexible protective nets, the case of falling rocks directly impacting the steel columns is not taken into consideration in general. However, there is a potential risk in this case. When the falling rock directly impacts the steel column, the direct impact is extremely prone to cause serious deformation, distortion or direct damages to the steel column, thereby affecting the bearing capacity of the entire structure, and significantly reducing the protection height, so that the protection reliability of the passive net systems is reduced.SUMMARY

[0005] In view of the above problems, the present invention provides a rockfall pre-sensing active avoiding type steel column supporting system, which is adapted to address the anticollision issues of steel columns in passive flexible protection net systems, and may remedy the drawbacks in the prior art.

[0006] In order to achieve the above object, the present invention employs the following technical solutions:

[0007] a rockfall pre-sensing active avoiding type steel column supporting system comprises: a rotatable column foot, a deflection steel column, a pulley node, a pre-sensing pull-up anchor rope and a connecting piece;

[0008] a Y-shaped lug plate is welded on a bottom plate of the rotatable column foot, a circular hole is provided on the Y-shaped lug plate and a pin shaft passes through the circular hole, and two limit springs for centering the column bottom lug plate are sleeved on the pin shaft; the rotatable column foot enables the steel column to also have a certain rotation capability in a horizontal direction.

[0009] A column bottom lug plate is welded to a column foot end of the deflection steel column, an inner wall of a hole of the column bottom lug plate is a circular ring surface tangent to a surface of the lug plate, the fit tolerance of the diameter of the hole and the diameter of the pin shaft is large, so as to help the steel column to rotate in the horizontal direction, and a column top end plate and a column top lug plate are welded to the top of a column body.

[0010] The pulley node is provided with double pulleys, and a pulley supporting frame is connected to the column top lug plate via an eyebolt and a shackle; a pre-sensing pull-up anchor rope is wound on each of the two pulleys, and two anchor points of each pull-up anchor rope are located on an uphill side and are distributed on two sides of a projection line (hereinafter referred to as the projection line) of an axis of the deflection steel column on a slope surface, wherein one anchor point is near the projection line and the other anchor point is far away from the projection line. A pressure relief ring is generally connected to the pre-sensing pull-up anchor rope.

[0011] Preferably, a difference Ad between an inner diameter of a minimum hole of the column bottom lug plate and an outer diameter of the pin shaft is determined by the following equation:

[0012] A d =XD

[0013] where D is the outer diameter of the pin shaft, X may be a value in a range of 0.1-0.125.

[0014] Preferably, an axial length lsof the limit spring on each side should satisfy the requirement in the following formula:

[0016] where dh is a hole edge distance of the hole of the Y-shaped lug plate.

[0017] Preferably, a distance between anchor points of the pre-sensing pull-up anchor rope should satisfy the following requirements:

[0018] dal=Min (at, 1)

[0020] where dai is the distance between two anchor points near the projection line, and da2 is the distance between two anchor points far away from the projection line, and the distance is in the unit of meter; Min is a function of the smaller one of two values, a may be a value in a range of 1 / 8-1 / 6, L is a length of the column body, and Lcis a column spacing in the passive flexible protection system.

[0021] Preferably, a distance dw between a midpoint of a line connecting the two anchor points near the projection line and a centre of the pin shaft should satisfy the requirement in the following formula:

[0023] where Max is a function of the greater one of two values, v is a maximum impact velocity that can be reached by a falling rock upon protection design, and t is a deflection reaction time of the steel column and takes a value of 0.08s.

[0024] Preferably, wheel disc surfaces of the duly-installed double pulleys are parallel to a plane where the pre-sensing pull-up anchor rope is located, and the pulley shaft is perpendicular to the plane where the pre-sensing pull-up anchor rope is located; a diameter at a groove of the pulley is not less than 8 times that of the steel wire rope used by the pre-sensing pull-up anchor rope.

[0025] A deflection trajectory of a column top node is controllable and may be determined in the following manner; if Oxyz is set as a right-hand rectangular coordinate system, an x-axis passes through four anchor points, a midpoint of the line connecting two anchor points near the projection line is a coordinate origin O, and an initial axis of the steel column is in a yz plane, the deflection trajectory of the column top node may be determined by the following equations:

[0026]

[0028] where y0and z0are the y and z coordinates of the centre of the pin shaft, and are known quantities after the system configuration is determined, Lais a length of one pre-sensing pull- up anchor rope, i.e., a sum of distances from two anchor points of the rope to the centre of the pulley shaft, which is a known quantity, and b is an intermediate variable.

[0029] As compared with the prior art, the present invention has the following advantageous effects:

[0030] When a falling rock might impact the steel column, it will firstly impact the pre-sensing pull-up anchor rope near the projection line above the steel column; since the probability of a complete symmetric impact is zero, a centroid of the falling rock is certainly closer to the pull- up anchor rope near a certain protection line; after the falling rock hits the pull-up anchor rope, the pulling force of the pull-up anchor rope increases abruptly. Due to the above special rope running manner of the pull-up anchor rope and arrangement manner of anchor points, the steel column will actively deflect towards the other side under the action of a resultant force of the pull-up anchor rope, thereby avoiding the impact from the falling rock. According to the difference in the shape and velocity of the falling rock and the impact position, the present invention can reduce the damages to the steel column from the impact or allow the steel column to completely avoid the impact, thereby substantially improving the survival capability of the steel column in the field environment and improving the impact resistance reliability and disaster prevention toughness of the passive net systems.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Fig. 1 is a schematic view of a rockfall pre-sensing active avoiding type steel column supporting system according to an embodiment;

[0032] Fig. 2 is a schematic isometric view of deflection of a rockfall pre-sensing active avoiding type steel column supporting system in the embodiment;

[0033] Fig. 3 is a schematic top view of the deflection of the rockfall pre-sensing active avoiding type steel column supporting system in the embodiment;

[0034] Fig. 4 is an isometric view of a rotatable column foot in the embodiment.

[0035] Fig. 5 is a schematic view illustrating the connection of the rotatable column foot anda deflection steel column foot in the embodiment;

[0036] Fig. 6 is an isometric view of a deflection steel column in the embodiment;

[0037] Fig. 7 is an isometric view of a pulley node in the embodiment.

[0038] Fig. 8 is an isometric view of a pre-sensing pull-up anchor rope and a connecting piece in the embodiment;

[0039] Fig. 9 is a schematic view illustrating the connection between the pulley node and the deflection steel column head in the embodiment.

[0040] Fig. 10 is a top view illustrating an implementation effect dynamic simulation result of an impact of a spherical falling rock in a test example.

[0041] Fig. 11 is a top view illustrating an implementation effect dynamic simulation result of an impact of a hexahedral falling rock in a test example.

[0042] In the figures: 1 -Rotatable column foot, 2-Deflection steel column, 3 -Pulley node, 4- Sensing pull-up anchor rope, Il-Bottom plate, 12-Y-shaped lug plate, 13-Pin shaft, 14-Limit spring, 21 -Column bottom lug plate, 22-Column body, 23-Column top end plate, 24-Column top lug plate, 31 -Pulley, 32-Pulley supporting frame, 33-Pulley shaft, 34-Eyebolt, 35-Shackle, 42-Steel wire rope, 42 -Pressure relief ring, 51 -Through shackle, 52-Figure-eight rope.DETAILED DESCRIPTION OF EMBODIMENTS

[0043] The present invention will be described in detail with reference in conjunction with figures and embodiments to further make the content of the present invention apparent. It should be appreciated that the embodiments are only intended to illustrate but not limit the present invention.

[0044] Embodiments

[0045] As shown in Figs. 1-3, a rockfall pre-sensing active avoiding type steel column supporting system comprises: a rotatable column foot 1, a deflection steel column 2, a pulley node 3, and a pre-sensing pull-up anchor rope 4.

[0046] As shown in Figs. 4-5, a Y-shaped lug plate 12 is welded on a bottom plate 11 of the rotatable column foot 1, a circular hole is provided on the Y-shaped lug plate 12 and a pin shaft 13 passes through the circular hole, and two limit springs 14 for centering the column bottom lug plate 21 are sleeved on the pin shaft 13; the rotatable column foot 1 enables the steel columnto also have a certain rotation capability in a horizontal direction.

[0047] As shown in Fig. 6, a column bottom lug plate 21 is welded to a column foot end of the deflection steel column 2, an inner wall of a hole of the column bottom lug plate 21 is a circular ring surface tangent to the surface of the lug plate, the fit clearance of a diameter of the hole and a diameter of the pin shaft 13 is large, so as to help the steel column to rotate in the horizontal direction, and a column top end plate 23 and a column top lug plate 24 are welded to the top of a column body 22.

[0048] As shown in Fig. 7, the pulley node 3 is provided with double pulleys 31, the two pulleys 31 are mounted on a pulley supporting frame 32 via a pulley shaft 33, and the pulley supporting frame 32 is connected to the column top lug plate 24 via an eyebolt 34 and a shackle 35; a pre-sensing pull-up anchor rope 4 is wound on each of the two pulleys 31, and two anchor points of each pull-up anchor rope are located on an uphill side and are distributed on two sides of a projection line (hereinafter referred to as the projection line) of an axis of the deflection steel column 2 on a slope surface, wherein one anchor point is near the projection line and the other anchor point is far away from the projection line. A pressure relief ring 42 is generally connected to the pre-sensing pull-up anchor rope 4.

[0049] As shown in Fig. 8, the pre-sensing pull-up anchor rope 4 comprises a steel wire rope 41, the pressure relief ring 42 is mounted on the steel wire rope 41, an end of the steel wire rope 41 is connected with a figure-eight rope 52, and a through shackle 51 is mounted on the figureeight rope 52.

[0050] Preferably, a difference Ad between an inner diameter of a minimum hole of the column bottom lug plate 21 and an outer diameter of the pin shaft 13 is determined by the following equation:

[0051] A d= D

[0052] where D is the outer diameter of the pin shaft 13, X may be a value in a range of 0.1- 0.125; if the diameter of the pin shaft 13 is 40 mm (determined according to the bearing capacity), the inner diameter of the minimum hole of the column bottom lug plate 21 may be 45 mm, and the fit tolerance thereof satisfies the above equation, to ensure that the deflection of the steel column in the horizontal direction is not hindered.

[0053] Preferably, an axial length lsof the limit spring 14 on each side should satisfy the requirement in the following formula:

[0055] where dh is a hole edge distance of the hole of the Y-shaped lug plate 12; if the hole edge distance is 100 mm (determined according to the bearing capacity), the axial length of the limit spring 14 on each side is not less than 27 mm, and may take a value 40 mm, to ensure that the deflection of the steel column in the horizontal direction is not hindered while keeping the column bottom lug plate 21 centered.

[0056] Preferably, a distance between anchor points of the pre-sensing pull-up anchor rope 4 should satisfy the following requirements:

[0057] dal= Mi n (aL , 1 )

[0059] where dai is the distance between two anchor points near the projection line, and da2 is the distance between two anchor points far away from the projection line, and the distance is in the unit of meter; Min is a function of the smaller one of two values, a may be a value in a range of 1 / 8-1 / 6, L is the length of the column body 22, and Lcis a column spacing in the passive flexible protection system. If the length of steel column L=4m (determined according to the demand for a protection height), the column spacing Lc=10m (a value commonly used in the industry); if a=l / 6.6, dai=0.6m and da2= 8m, the above requirements of the above formulas are satisfied.

[0060] Preferably, a distance dw between a midpoint of a line connecting two anchor points near the projection line and a centre of the pin shaft 13 should satisfy the requirement in the following formula:

[0061] dw^Max (L , 2vt)

[0062] where Max is a function of the greater one of two values, v is a maximum impact velocity that can be reached by a falling rock upon protection design, and t is a deflection reaction time of the steel column and takes a value of 0.08s. In order to satisfy the reaction time of the deflection of the steel column, it is usually v=25m / s in the industry, and dw=4m.

[0063] As shown in Fig. 9, preferably, wheel disc surfaces of the duly- installed double pulleys 31 are parallel to a plane where the pre-sensing pull-up anchor rope 4 is located, and the pulley shaft 33 is perpendicular to the plane where the pre-sensing pull-up anchor rope 4 is located; a diameter at a groove of the pulley 31 is not less than 8 times that of the steel wire rope 41 usedby the pre-sensing pull-up anchor rope 4. If the diameter of the pull-up anchor rope is 20 mm, the diameter at the groove of the pulley 31 may be 160 mm, and the pulley 31 of a corresponding specification is selected according to this value.

[0064] A deflection trajectory of a column top node is controllable and may be determined in the following manner; if Oxyz is set as a right-hand rectangular coordinate system, the x-axis passes through four anchor points, the midpoint of the line connecting two anchor points near the projection line is the coordinate origin O, and the initial axis of the steel column is in the yz plane, the deflection trajectory of the column top node may be determined by the following equations:

[0067] where y0and z0are the y and z coordinates of the centre of the pin shaft 13, and are known quantities after the system configuration is determined, Lais the length of one presensing pull-up anchor rope 4, i.e., a sum of distances from two anchor points of the rope to the centre of the pulley shaft 33, which is a known quantity, and b is an intermediate variable.

[0068] TEST EXAMPLES

[0069] In order to better represent the implementation effect of the present invention, a finite element dynamic simulation model is established based on LS-DYNA explicit dynamic simulation platform, and relevant parameters are as follows: the length of the steel column is L=4 m, the distance between two anchor points near the projection line is dai=0.6m, the distance between two anchor points far away from the projection line is da2=8 m, the distance between the midpoint of the line connecting two anchor points near the projection line and the column foot is dw=4 m, the axis of the steel column is horizontally arranged, the steel column is made of a round pipe having a cross section P219*8, and the diameter of the pull-up anchor rope is 20 mm.

[0070] The pulley node is simulated by a special slidable node, which can achieve an inner boundary effect equivalent to the pulley, the anchor point and the column foot node are in the same vertical plane, and the column foot is set to be hinged. The impact energy is 800 kJ, theimpact velocity is 25 m / s, the impact is vertically downward, and the mass of the falling rock is 2500 kg. There are two working conditions: one is that the falling rock is a spherical falling rock and the other is that the falling rock is a cubic falling rock, the diameter of the spherical falling rock is 1.25 m, and a length of sides of the cubic falling rock is 1 m, as shown in Fig. 10 and Fig. 11.

[0071] In the working condition with the impact from the spherical falling rock, a horizontal projection point of the center of gravity of the spherical falling rock is 0.1 m to the right of the axis of the steel column, and is very close to the axis of symmetry. In the working condition with the impact from the cubic falling rock, the horizontal projection point of the center of gravity of the cubic falling is 0. 3 m to the right of the axis of the steel column, and the working condition is one having slightly large asymmetry.

[0072] The simulation result shows that although the falling rock still collides with the steel column in the working condition with the impact from the spherical falling rock, the buckling damage of the steel column is low and there is no damage (a traditional steel column supporting system is considered as being damaged at this time) because the steel column deflects away in advance, and the steel column still have a certain bearing capacity (see Fig. 10).

[0073] In the working condition with the impact from the cubic falling rock, the steel column can completely avoid the collision with the falling rock, thereby achieving a good protection effect (see Fig. 11). The above-mentioned dynamic simulation process shows that the rockfall pre-sensing active avoiding type steel column supporting system has a good steel column protection effect.

[0074] The present invention and its embodiments have been described illustratively above, the description is non-limiting, what are shown in the figures are only one of embodiments of the present invention, and the actual structure is not limited thereto. If those having ordinary skill in the art, as inspired by the above, devises structural modes and embodiments similar to the technical solution without making inventive efforts without departing from the spirit of the present invention, all the devised structural modes and embodiments should fall within the scope of the present invention.

Claims

I / We Claim:

1. A rockfall pre-sensing active avoiding type steel column supporting system, comprising: a rotatable column foot (1), a deflection steel column (2), a pulley node (3), a presensing pull-up anchor rope (4) and a connecting piece (5), the rotatable column foot (1) being hinged with a bottom of the deflection steel column (2), the pulley node (3) being mounted on top of the deflection steel column (2), the pre-sensing pull-up anchor rope (4) being sleeved on the pulley node (3), two ends of the pre-sensing pull-up anchor cord (4) being respectively secured to an anchor point, characterized in that: a Y-shaped lug plate (12) is welded on a bottom plate (11) of the rotatable column foot (1), and a circular hole is provided on the Y-shaped lug plate (12) and a pin shaft (13) passes through the circular hole; a column bottom lug plate (21) is welded to a column foot end of the deflection steel column (2), the column bottom lug plate (21) is sleeved on the pin shaft (13), and limit springs (14) for centering the column bottom lug plate (21) are sleeved on the pin shaft (13); a column top end plate (23) and a column top lug plate (24) are welded to the top of a column body (22) of the deflection steel column (2), and the pulley node (3) is mounted on the column top lug plate (24); the pulley node (3) comprises a pulley supporting frame (32), a pulley shaft (33) and two pulleys (31), the two pulleys (31) are mounted on the pulley supporting frame (32) via the pulley shaft (33), and the pulley supporting frame (32) is connected to the column top lug plate (24) via an eyebolt (34) and a shackle (35); a pre-sensing pull-up anchor rope (4) is wound on each of the two pulleys (31), and two anchor points of each pre-sensing pull-up anchor rope (4) are located on an uphill side and are distributed on two sides of a projection line of an axis of the deflection steel column (2) on a slope surface, wherein one anchor point is near the projection line and the other anchor point is far away from the projection line.

2. The rockfall pre-sensing active avoiding type steel column supporting system according to claim 1, characterized in that a through hole is provided on the column bottom lug plate (21), a hole wall of the through hole is a circular ring surface tangent to a surface of the column bottom lug plate (21), and a difference Ad between an inner diameter of a minimum hole of the column bottom lug plate (21) and an outer diameter of the pin shaft (13) is determined by the following equation:A d — XD where D is the outer diameter of the pin shaft, X may be a value in a range of 0.1-0.125.

3. The rockfall pre-sensing active avoiding type steel column supporting system according to claim 1, characterized in that an axial length lsof the limit springs (14) satisfies the requirement in the following formula:where dh is a hole edge distance of the hole of the Y-shaped lug plate (12).

4. The rockfall pre-sensing active avoiding type steel column supporting system according to claim 1, characterized in that the pre-sensing pull-up anchor rope (4) comprises a steel wire rope (41), a pressure relief ring (42) is mounted on the steel wire rope (41), an end of the steel wire rope (41) is connected with a figure-eight rope (52), and a through shackle (51) is mounted on the figure-eight rope (52); a distance between anchor points of the pre-sensing pull-up anchor rope (4) satisfies the following requirements:where dai is the distance between two anchor points near the projection line, and da2 is the distance between two anchor points far away from the projection line, and the distance is in the unit of meter; Min is a function of the smaller one of two values, a may be a value in a range of 1 / 8-1 / 6, L is a length of the column body (22), and Lcis a column spacing in the passive flexible protection system.

5. The rockfall pre-sensing active avoiding type steel column supporting system according to claim 4, characterized in that a distance dw between a midpoint of a line connecting two anchor points near the projection line and a centre of the pin shaft (13) satisfies the requirement in the following formula: dw;5Max (L, 2vt) where Max is a function of the greater one of two values, v is a maximum impact velocity that is reached by a falling rock upon protection design, and t is a deflection reaction time of the steel column and takes a value of 0.08s.

6. The rockfall pre-sensing active avoiding type steel column supporting systemaccording to claim 1, characterized in that wheel disc surfaces of the pulleys (31) are parallel to a plane where the pre-sensing pull-up anchor rope (4) is located, and the pulley shaft (33) is perpendicular to the plane where the pre-sensing pull-up anchor rope (4) is located; a diameter at a groove of the pulley (31) is not less than 8 times that of the steel wire rope (41) used by the pre-sensing pull-up anchor rope (4).

7. The rockfall pre-sensing active avoiding type steel column supporting system according to claim 1, characterized in that a deflection trajectory of a column top node of the deflection steel column (2) is controllable and is determined in the following manner: if Oxyz is set as a right-hand rectangular coordinate system, an x-axis passes through four anchor points, a midpoint of the line connecting two anchor points near the projection line is a coordinate origin O, and an initial axis of the deflection steel column (2) is in a yz plane, and the deflection trajectory of the column top node is determined by the following equations:where y0and z0are the y and z coordinates of a centre of the pin shaft (13), and are known quantities after the system configuration is determined, Lais a length of one pre-sensing pull-up anchor rope, i.e., a sum of distances from two anchor points of the rope to the centre of the pulley shaft (33), which is a known quantity, and b is an intermediate variable.

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