CN118065267A - Assembled blocking net protection structure suitable for 5000KJ falling stone impact energy level - Google Patents

Abstract

The invention discloses an assembled blocking net protection structure suitable for a 5000KJ falling stone impact energy level, which belongs to the field of falling stone protection and comprises a blocking net main body arranged between hillsides on two sides of a channel, and a plurality of assembled supporting columns with top ends connected with the blocking net main body, wherein each assembled supporting column comprises a top end steel tube concrete column and a bottom end reinforced concrete column, the blocking net main body is fixed on the top end steel tube concrete column, the bottom end of the top end steel tube concrete column is assembled and connected with the top end of the bottom end reinforced concrete column through a high-strength bolt, and the bottom end reinforced concrete column is embedded at the bottom end of the mountain. The assembled blocking net protection structure with the structure and suitable for the 5000KJ falling stone impact energy level is adopted, and the top steel tube concrete column and the bottom reinforced concrete column are connected through the assembled supporting columns and the high-strength bolts, so that the bottom reinforced concrete column can be replaced and recycled.

Description

Prefabricated barrier net protection structure suitable for 5000KJ rockfall impact level

Technical Field

The invention relates to the technical field of rockfall protection, and in particular to an assembled barrier net protection structure suitable for a 5000KJ rockfall impact energy level.

Background technique

High-level collapse and rockfall is a common geological disaster in complex and dangerous mountainous areas. It is highly concealed, has strong disaster-causing capacity, and has a large impact energy, threatening the lives of fellow personnel. Therefore, prevention and control structures need to be set up in areas prone to geological disasters. Common prevention and control measures can be divided into two categories: active reinforcement in situ and passive protection. Active reinforcement in situ mainly adopts active protection nets, lattice anchors (cables) and support columns, while passive protection mainly adopts passive protection nets, sheds and caves. Due to the high difficulty of in-situ remediation in complex and dangerous mountainous areas, such as the need to set up super-high scaffolding, passive protection structures are widely used in the prevention and control of high-level collapse and rockfall.

Existing passive protection structures include:

Patent CN111549804B discloses a reinforced passive protection system for road cutting slope and its construction method. The structure is arranged on the broken rock road cutting slope, including a road cutting wall, a reinforced gabion retaining wall and a passive protection net. The road cutting wall is arranged at the foot of the road cutting slope, the reinforced gabion retaining wall is arranged at the top of the road cutting wall, and the passive protection net is arranged at the top of the reinforced gabion retaining wall; the reinforced gabion retaining wall is composed of a plurality of reinforced gabions, and the adjacent reinforced gabions are connected by folded steel wire ropes and/or buckles; the passive protection net includes a base, and the passive protection net is fixed to the reinforced gabion retaining wall through a plurality of spaced bases; a plurality of base through holes are arranged on the base, and a plurality of PVC pipes are arranged vertically in the reinforced gabion retaining wall at positions corresponding to the base through holes, and a steel pipe is arranged in the PVC pipe, and the steel pipe passes through the base through hole and extends out of the base, and cement mortar is arranged in the steel pipe. Its advantages are: the structure can effectively protect the foot of the steel column from the harm of falling rocks, but its protection height is relatively low.

At the same time, the researchers also conducted corresponding research and development on the design of the support rope. For example: Patent CN105256730A discloses an active-passive hybrid tailing high-performance protection net, which uses multiple parallel support ropes to replace the traditional upper and lower support ropes. By lifting the lowest parallel support rope a certain distance from the ground, an opening space is formed for the lower rockfall to pass through, so that the system has an opening feature, which is convenient for the rockfall to enter the tailing mesh area; the mesh is divided into an intercepting mesh and a tailing mesh, so that a certain volume of rockfall can pass through the lower opening space of the lowest parallel support rope after being intercepted, enter the tailing mesh area, and move along the tailing direction to the preset collection area. The tailing mesh has a certain trajectory control effect on the collapse and rockfall occurring in the covered area. Its advantages are: it draws on the advantages of the active and passive protection net systems, and has both a high protection level and easy cleaning.

Patent CN115450234B discloses a protective barrier structure for preventing high-energy rockfall impact in complex mountainous areas. The structure is arranged in a support pile array between the hillsides on both sides of the channel. The support pile array is arranged in a straight line, including at least two support piles, and a specific spacing is preset between two adjacent support piles; all support piles are fixed below the mountain, and a barrier net is connected between the support piles, and the barrier net passes through the support pile array and extends and is fixed on the mountain slopes on both sides; multiple tension plates are arranged on the mountain slope, one side of the tension plate is fixed to the mountain slope through a reverse prestressed anchor cable, and the other side of the tension plate is connected to the barrier net for anchoring the barrier net; the height of the barrier net is ≥6m, the yield elongation of the barrier net material is ≥0.2%, and the fracture elongation is ≥20%. Advantages: It can improve the protection level of the traditional flexible barrier net, and has the function of easy maintenance of the barrier net after being impacted by collapse and rockfall.

Although the above research can adapt to higher barrier energy levels, there is still a relative lack of research at home and abroad on replaceable assembled barrier net protection structures with impact energy of more than 5000kJ, which is not suitable for high-level and high-frequency high-altitude collapse and rockfall geological disasters.

Summary of the invention

In order to solve the above problems, the present invention provides an assembled barrier net protection structure suitable for 5000KJ rockfall impact energy level. By setting assembled support columns and using high-strength bolts to connect the top steel tube concrete column and the bottom reinforced concrete column, the bottom reinforced concrete column can be replaced and recycled.

To achieve the above-mentioned purpose, the present invention provides an assembled barrier net protection structure suitable for a 5000KJ rockfall impact energy level, including a barrier net main body arranged between the hillsides on both sides of the ditch, and a plurality of assembled support columns connected to the barrier net main body at the top, the assembled support columns including a top steel tube concrete column and a bottom reinforced concrete column, the barrier net main body is fixed on the top steel tube concrete column, the bottom end of the top steel tube concrete column is assembled and connected to the top end of the bottom reinforced concrete column through high-strength bolts, and the bottom reinforced concrete column is pre-buried in the bottom of the mountain.

Preferably, the height of the barrier net main body is ≥6m, the yield elongation of the barrier net main body is ≥0.2%, and the breaking elongation of the barrier net main body is ≥20%.

Preferably, the main body of the barrier net is a grid structure composed of multiple bundles of transverse steel strands and multiple bundles of longitudinal steel strands that are crisscrossed, and the transverse steel strands and the longitudinal steel strands are connected by fasteners;

Both ends of the transverse steel strands pass through the top steel tube concrete column and are vertically connected to the slopes on both sides of the channel through tension plates and reverse prestressed anchor cables;

The materials of transverse steel strands and longitudinal steel strands are both NPR steel.

Preferably, the spacing between two adjacent bundles of transverse steel strands satisfies the following relationship:

Where h is the distance between two adjacent transverse steel strands; n is the number of transverse steel strands; V is the equivalent volume of the rockfall;

And the number n of transverse steel strands satisfies the following relationship:

MgH≤n(W ₁ +W ₂ ) (2)

W ₁ = F ₂ × L × Δ ₁ - F ₁ × L × Δ ₀ (3)

W ₂ = F ₂ × L × (Δ ₂ - _{Δ 1} ) (4)

Wherein, M is the mass of the rockfall; g is the acceleration of gravity; H is the height difference from the rockfall collapse position to the contact position of the collision impact barrier net body; _W1 is the work done by the single-bundle transverse steel strand in the elastic stage; _W2 is the work done by the single-bundle transverse steel strand in the plastic stage; _F1 is the preload applied to the single-bundle transverse steel strand; _F2 is the yield critical force of the single-bundle transverse steel strand; L is the length of the single-bundle transverse steel strand; _Δ0 is the preload elongation of the single-bundle transverse steel strand; _Δ1 is the yield elongation of the single-bundle transverse steel strand; _Δ2 is the plastic deformation elongation of the single-bundle transverse steel strand.

Preferably, the fasteners include T-shaped fasteners and cross-shaped fasteners, and the materials of the T-shaped fasteners and the cross-shaped fasteners are both NPR alloy steel;

Wherein, the T-shaped fastener is used to connect the set bundle of transverse steel strands at the top and the intersecting single bundle of vertical steel strands, and the set bundle of transverse steel strands at the bottom and the intersecting single bundle of vertical steel strands;

The cross-shaped fastener is used to connect the single bundle of transverse steel strands between the set bundle of transverse steel strands at the top of the connection and the set bundle of transverse steel strands at the bottom and the intersecting single bundle of vertical steel strands;

Set the bundle to at least two bundles.

Preferably, the T-shaped fastener comprises a ferrule for passing through the top setting bundle transverse steel strand or the bottom setting bundle transverse steel strand, a U-shaped connecting fork ear connected to the ferrule at one end, and a wedge assembly connected to the other end of the U-shaped connecting fork ear, the wedge assembly comprising a wedge ferrule connected to the outer wall of the U-shaped connecting fork ear at one end through a locking nut, a wedge-shaped cavity is provided inside the wedge ferrule away from one end of the U-shaped connecting fork ear, a wedge-shaped clamping ring is axially slidably arranged in the wedge-shaped cavity, and a vertical steel strand is clamped in the wedge clamping ring; after the U-shaped connecting fork ear is extended into the wedge ferrule, it is crimped with the wedge clamping ring through a clamping nut, and the clamping nut is also fixedly connected to the outer circumferential side of the vertical steel strand passing through the wedge clamping ring;

The cross-shaped fastener includes a base and cover plates which are bolted to the upper and lower ends of the base. A transverse groove and a longitudinal groove are respectively provided between the top end of the base and the corresponding cover plate and between the bottom end of the base and the corresponding cover plate. Transverse steel strands and longitudinal steel strands are respectively engaged in the transverse groove and the longitudinal groove.

Preferably, the assembled support column is divided into j equal parts from the top to the bottom according to each section length h ₁ , and the bending moment calculation formula of the assembled support column is as follows:

In the formula, τ is the bending moment of the prefabricated support column; E is the elastic modulus of the prefabricated support column; I is the cross-sectional inertia moment of the prefabricated support column; _xk is the horizontal deflection of the k-th prefabricated support column; _xk-1 is the horizontal deflection of the k-1-th prefabricated support column; _xk+1 is the horizontal deflection of the k+1-th prefabricated support column; and k∈(2,j-1).

Preferably, a steel pad is provided between the top steel tube concrete column and the bottom reinforced concrete column, a plurality of wing plates are provided at the top of the steel pad and around the top steel tube concrete column, the plurality of wing plates enclose a cavity for clamping the plurality of top steel tube concrete columns, and the bottom reinforced concrete column is connected to each other by high-strength bolts between two adjacent wing plates, and the connection between the top steel tube concrete column and the bottom reinforced concrete column is filled with a caulking agent;

The height ratio of the top steel tube concrete column to the bottom reinforced concrete column is 5:3, and the cross-section of the bottom reinforced concrete column is a square that meets the following requirements:

L≥2D (6)

Where L is the cross-sectional side length of the bottom reinforced concrete column, and D is the cross-sectional diameter of the top steel tube concrete column; the cross-sectional diameter of the top steel tube concrete column is determined by the finite difference method.

Preferably, the top steel tube concrete column is a structure in which concrete is poured outside the steel tube, and the surface of the steel tube is coated with polyaspartic acid resin;

The depth of the bottom reinforced concrete column buried in the ground is ≥5m. The bottom reinforced concrete column is a structure with a concrete protective layer poured on a steel cage. The steel cage is composed of transverse steel bars and longitudinal steel bars arranged in an array. Multiple longitudinal ribbed steel bars are inserted in the steel cage. The transverse steel bars and longitudinal steel bars are tied and connected, and the spacing between longitudinal steel bars is ≤0.2m, the spacing between transverse steel bar layers is ≤0.3m, and the thickness of the concrete protective layer is ≥0.05m;

A steel gasket is placed at the top of the bottom reinforced concrete column. A threaded hole is opened at the position of the steel gasket corresponding to the longitudinal ribbed steel bar. The top of the longitudinal ribbed steel bar is threadedly connected to the threaded hole and extends out through the threaded hole. The extension length of the longitudinal ribbed steel bar is 0.5m.

The formula for determining the number of longitudinal ribbed steel bars is as follows:

Where m is the number of longitudinal ribbed steel bars, τ is the bending moment of the prefabricated support column, f _y is the yield strength of the longitudinal ribbed steel bars, B _s is the cross-sectional area of the longitudinal ribbed steel bars, h ₀ is the cross-sectional height of the prefabricated support column, and a' _s is the thickness of the concrete cover.

Preferably, a plurality of prestressed anchor cables are evenly fixed on the top steel tube concrete column from top to bottom, and the plane formed by the plurality of prestressed anchor cables is perpendicular to the plane where the retaining net main body is located;

The prestressed anchor cables are anchored on the ground beams, and the ground beams are reversely anchored in the mountain.

The present invention has the following beneficial effects:

1. By adjusting the height of the main body of the barrier net, the yield elongation and fracture elongation of the material, the protection level of the traditional flexible barrier net can be broken through and the high-energy impact protection function can be achieved;

2. By setting up assembled support columns and using high-strength bolts to connect the top steel tube concrete column and the bottom reinforced concrete column, the bottom reinforced concrete column can be replaced and recycled;

3. By increasing the height of the reinforced concrete column at the bottom, the height of the steel tube concrete column at the top can be increased. Then the tension plate is used to connect the main body of the retaining net with the hillside, so that the retaining net can be replaced after the impact of landslides and falling rocks;

4. By calculating the spacing and number of transverse steel strands, the barrier protection structure can achieve high-energy impact protection under the conditions that the height of the barrier net body is ≥6m, the yield elongation of the barrier net body is ≥0.2%, and the fracture elongation is ≥20%;

5. Based on the analysis of the impact characteristics of falling rocks, prestressed anchor cables are arranged at different intervals, and the number of prestressed anchor cables is pre-designed to ensure the stability of the entire prefabricated support piles.

The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the installation structure of an assembled barrier net protection structure suitable for a 5000KJ rockfall impact energy level according to the present invention;

FIG2 is a schematic structural diagram of a T-shaped fastener of an assembled barrier net protection structure suitable for a 5000KJ rockfall impact energy level according to the present invention;

FIG3 is a schematic structural diagram of a cross fastener of an assembled barrier net protection structure suitable for a 5000KJ rockfall impact energy level according to the present invention.

Among them: 1. The main body of the retaining net; 11. The horizontal steel strand; 12. The longitudinal steel strand; 2. The assembled support column; 21. The top steel tube concrete column; 22. The bottom reinforced concrete column; 3. The tension plate; 4. The reverse prestressed anchor cable; 5. The prestressed anchor cable; 6. The T-type fastener; 61. The ferrule; 62. The U-type connecting fork ear; 63. The locking nut; 64. The compression nut; 65. The wedge-shaped clamp; 66. The wedge-shaped ferrule; 7. The cross-shaped fastener.

Detailed ways

In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

Like reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

The present invention is designed to develop a replaceable assembled barrier net protection structure suitable for high-energy rockfall impact, so as to achieve protection in harsh scenarios with frequent high-altitude collapse and rockfall and large impact energy: as shown in Figures 1-3, an assembled barrier net protection structure suitable for 5000KJ rockfall impact energy level, including a barrier net main body 1 arranged between the hillsides on both sides of the ditch, and a plurality of assembled support columns 2 connected to the barrier net main body 1 at the top, the assembled support columns 2 including a top steel tube concrete column 21 and a bottom reinforced concrete column 22, the top steel tube concrete column 21 is fixed with the barrier net main body 1, the bottom end of the top steel tube concrete column 21 is assembled and connected to the top of the bottom reinforced concrete column 22 by high-strength bolts, the bottom reinforced concrete column 22 is pre-buried in the bottom of the mountain, and the assembled support columns 2 can realize the functions of easy maintenance and replaceability of the structure.

The height of the barrier net main body 1 is ≥6m, the yield elongation of the barrier net main body 1 is ≥0.2%, and the fracture elongation of the barrier net main body 1 is ≥20%, which can break through the impact energy resistance of the traditional passive protection net, making the barrier net protection structure suitable for high-energy impact protection. The overall protection height is also 3 to 5 times that of the ordinary passive protection net, which greatly improves the protection effect on the mountain.

In this embodiment, the parameters of the prefabricated support column 2 can be determined by trial calculation. For example, in a certain case, the prefabricated support pile is 43m long, the steel tube concrete cantilever section is 28m, the fixed section is 15m, the trial calculation takes the pile section as 2.0×3.0m, 16 rows of anchor cables are set on the pile top, and the anchor cable design load is 100kN. It is calculated that: the maximum bending moment of the support pile is 76734.40kN.m, the maximum shear force is 5898.7064kN, the pile top displacement is 0.041m, and a total of 108 vertical φ32mm main bars are arranged on the long side of the single side of the support pile, and 12 vertical φ32mm main bars are arranged on the short side. The lateral allowable bearing capacity of the pile is 9000kPa, which meets the requirements.

The main body 1 of the retaining net is a grid structure composed of a plurality of crisscrossed bundles of transverse steel strands 11 and a plurality of longitudinal steel strands 12, and the transverse steel strands 11 and the longitudinal steel strands 12 are connected by fasteners; both ends of the transverse steel strands 11 pass through the top steel tube concrete column 21 and are respectively vertically connected to the slope surfaces of the hillsides on both sides of the channel through the tension plates 3 and the reverse prestressed anchor cables 4; the transverse steel strands 11 and the longitudinal steel strands 12 are both made of NPR steel.

In this embodiment, the tension plates 3 are fixed on the upslope, and multiple bundles of transverse steel strands 11 can be anchored on each tension plate 3. In order to achieve the fixation and tensioning effect of the transverse steel strands 11 when multiple transverse steel strands 11 are fixed on the tension plates 3, the number of reverse prestressed anchor cables 4 can be set as follows: the ratio of the number of reverse prestressed anchor cables 4 on both sides of each tension plate 3 to the number of transverse steel strands 11 is ≥0.3, and the ratio of the height of each tension plate 3 above the slope surface to the height below the slope surface is ≤7.4.

The spacing between two adjacent bundles of transverse steel strands 11 is determined by calculation based on the design impact energy, and the spacing between the vertical steel strands is determined based on the spacing between the transverse steel strands 11, that is, by limiting the spacing between the vertical steel strands 12, it is possible to avoid the situation where the mountain collapse and falling rocks pass through the gaps between the strands due to the large spacing. In addition, in order to fully consider the corresponding relationship between the spacing between the vertical steel strands 12 and the falling rocks, calculations and analyses can be performed to ensure that the spacing between the adjacent vertical steel strands 12 meets the rockfall protection in the corresponding setting scenario.

The spacing between two adjacent bundles of vertical steel strands 12 satisfies the following relationship:

Wherein, h is the distance between two adjacent transverse steel strands 11; n is the number of transverse steel strands 11; V is the equivalent volume of the falling rock;

When studying the energy of falling rocks when they fall obliquely from a mountain slope (including rolling, sliding, and bouncing, etc.), it is generally converted into the energy of the falling rocks in free fall based on prior calculations and test experience in actual scenarios. That is, it is converted into an equivalent value of the vertical height of the mountain slope, thereby replacing the numerical value of the mountain slope height.

The above-mentioned transverse steel strands 11 and longitudinal steel strands 12 have both high yield strength and high uniform elongation, and the stress deformation process is mainly divided into the following three stages: elastic stage, plastic stage and destruction stage. When the transverse steel strands 11 are initially applied with preload _F1 , the transverse steel strands 11 of the barrier net are in the elastic stage at this time; when the transverse steel strands 11 of the barrier net are impacted by landslides and falling rocks, the transverse steel strands 11 of the barrier net begin to transition from the elastic stage to the plastic stage, that is, from the initial preload _F1 to the critical force _F2 stage of yield; when the transverse steel strands 11 of the barrier net are impacted by landslides and falling rocks and reach the critical force _F2 of yield, the transverse steel strands 11 of the barrier net undergo plastic deformation. Through the above analysis and the setting of the barrier net, it can be ensured that the impact of falling rocks can only reach the plastic deformation stage of the transverse steel strands 11 of the barrier net.

The main energy conversion in the whole process of falling rocks impacting the retaining net body 1 and stopping is: the gravitational potential energy of the collapsed falling rocks is converted into kinetic energy, which impacts the retaining net body 1. The retaining net body 1 has good elongation, and the extension work absorbs the impact energy and stops.

By fully considering the rockfall and mountain conditions at the location where the blocking protection structure is set, and considering the different parameters of the elastic stage and the plastic stage according to the characteristics of the transverse steel strands 11 themselves, the number of transverse steel strands 11 that should be set is finally obtained, and the spacing between adjacent transverse steel strands 11 is finally obtained according to the number of transverse steel strands 11 that should be set and the rockfall conditions. The blocking net arranged according to the corresponding spacing between the transverse steel strands 11 can complete high-energy protection in the preset rockfall and mountain conditions.

And the number n of the transverse steel strands 11 satisfies the following relationship:

MgH≤n(W ₁ +W ₂ ) (2)

W ₁ = F ₂ × L × Δ ₁ - F ₁ × L × Δ ₀ (3)

W ₂ = F ₂ × L × (Δ ₂ - _{Δ 1} ) (4)

Wherein, M is the mass of the falling rock; g is the acceleration of gravity; H is the height difference from the falling rock collapse position to the contact position of the collision impact barrier net body 1; _W1 is the work done in the elastic stage of the single-bundle transverse steel strand 11; _W2 is the work done in the plastic stage of the single-bundle transverse steel strand 11; _F1 is the preload applied to the single-bundle transverse steel strand 11; _F2 is the yield critical force of the single-bundle transverse steel strand 11; L is the length of the single-bundle transverse steel strand 11; _Δ0 is the preload elongation of the single-bundle transverse steel strand 11; _Δ1 is the yield elongation of the single-bundle transverse steel strand 11; _Δ2 is the plastic deformation elongation of the single-bundle transverse steel strand 11.

Among them, the value of F ₁ preload can be selected in different application scenarios, F ₁ (0≤F ₁ ≤350kN). The specific values of the equivalent volume V of the falling rock and the mass M of the falling rock can be set according to the historical data of the application scenario, and the threshold degree of the retaining structure can be considered to make positive or conservative calculations.

At the same time, by limiting the number of reverse prestressed anchor cables 4 and the number of transverse steel strands 11, as well as the thickness of the tension plate 3, it can be ensured that the tension plate 3 always has a good fixing and tensioning effect on the transverse steel strands 11. After being impacted by landslides and falling rocks, the tension plate 3 can be removed to replace the transverse steel strands 11. The structural dimensions of the tension plate 3 are designed according to the reinforcement configuration and cross-sectional dimensions based on the force of the retaining net and the anchoring force of the reverse anchoring mountain.

In this embodiment, the above parameters are determined by the following trial calculation: first set an initial size, then perform reinforcement, and finally verify the calculation. In a certain case, the cross-sectional dimensions of the tension plate 3 can be 1.0m high, 0.95m wide, 2.2m thick above the ground, and 0.3m below the ground. Then, the bending reinforcement calculation of the normal section is performed. After the reinforcement is completed, the bearing capacity of the inclined section and the shear bearing capacity of the tension plate 3 are calculated. If all the verifications are passed, the requirements are met. If the verification fails, continue the trial calculation. If the safety redundancy is too high, reduce the size and reinforcement.

The fasteners include T-shaped fasteners 6 and cross-shaped fasteners 7, both of which are made of NPR alloy steel; wherein the T-shaped fastener 6 is used to connect the set bundle transverse steel strands 11 at the top and the intersecting single bundle vertical steel strands, and the set bundle transverse steel strands 11 at the bottom and the intersecting single bundle vertical steel strands; the cross-shaped fastener 7 is used to connect the single bundle transverse steel strands 11 located between the set bundle transverse steel strands 11 at the top and the set bundle transverse steel strands 11 at the bottom and the intersecting single bundle vertical steel strands; the set bundle is at least two bundles.

The T-shaped fastener 6 includes a sleeve 61 for passing through the top setting bundle transverse steel strand 11 or the bottom setting bundle transverse steel strand 11, a U-shaped connecting fork ear 62 connected to the sleeve 61 at one end, and a wedge component connected to the other end of the U-shaped connecting fork ear 62. The wedge component includes a wedge sleeve 6661 connected to the outer wall of the U-shaped connecting fork ear 62 through a locking nut 63 at one end. A wedge-shaped cavity is provided inside the wedge sleeve 6661 away from one end of the U-shaped connecting fork ear 62. A wedge-shaped retaining ring 65 is axially slidably arranged in the wedge-shaped cavity. The wedge retaining ring 65 A vertical steel strand is clamped inside; the U-shaped connecting fork ear 62 extends into the interior of the wedge-shaped clamping sleeve 6661 and is crimped with the wedge-shaped clamping ring 65 through the clamping nut 64. The clamping nut 64 is also fixedly connected to the outer circumference of the vertical steel strand passing through the wedge-shaped clamping ring 65; when the wedge-shaped assembly is used to fix the longitudinal steel strand 12, one end of the longitudinal steel strand 12 is fixed by the clamping nut 64, and then the locking nut 63 is cooperated with the wedge-shaped clamping sleeve 6661 to achieve the extrusion of the wedge-shaped clamping ring 65, so that the wedge-shaped clamping ring 65 and the longitudinal steel strand 12 are clamped and fixed.

The cross-shaped fastener 7 includes a base and cover plates which are bolted to the upper and lower ends of the base. A transverse groove and a longitudinal groove are respectively provided between the top of the base and the corresponding cover plate and between the bottom of the base and the corresponding cover plate. The transverse groove and the longitudinal groove respectively clamp the transverse steel strand 11 and the longitudinal steel strand 12. When the transverse steel strand 11 and the longitudinal steel strand 12 are fixed by the cross fastener, the transverse steel strand 11 and the longitudinal steel strand 12 are respectively placed in the transverse groove and the longitudinal groove on both sides of the base, and then the two cover plates are covered on both sides of the base, and the cover plates and the base are fixed by bolts, so as to complete the fixing of the transverse steel strand 11 and the longitudinal steel strand 12.

The assembled support column 2 is divided into j equal parts from the top to the bottom according to the length of each section h _1. The bending moment calculation formula of the assembled support column 2 is as follows:

In the formula, τ is the bending moment of the assembled support column 2; E is the elastic modulus of the assembled support column 2; I is the cross-sectional inertia moment of the assembled support column 2; _xk is the horizontal deflection of the k-th assembled support column 2; _xk-1 is the horizontal deflection of the k-1-th assembled support column 2; _xk+1 is the horizontal deflection of the k+1-th assembled support column 2; and k∈(2,j-1).

The bending moment of the fabricated support piles can also be simulated using finite element method;

A steel plate is provided between the top steel tube concrete column 21 and the bottom reinforced concrete column 22. A plurality of wing plates are provided at the top of the steel plate and around the top steel tube concrete column 21. The plurality of wing plates enclose a cavity for clamping the plurality of top steel tube concrete columns 21. The bottom reinforced concrete column 22 is connected between two adjacent wing plates via high-strength bolts. The connection between the top steel tube concrete column 21 and the bottom reinforced concrete column 22 is filled with a caulking agent. The height ratio between the top steel tube concrete column 21 and the bottom reinforced concrete column 22 is 5:3, and the cross section of the bottom reinforced concrete column 22 is a square that meets the following requirements:

L≥2D (6)

Wherein, L is the cross-sectional side length of the bottom reinforced concrete column 22, and D is the cross-sectional diameter of the top steel tube concrete column 21;

The cross-sectional dimensions of the top concrete-filled steel tube column 21 are determined by using the finite difference method based on the impact force transmitted to the top concrete-filled steel tube column 21 by the transverse steel strands 11 .

The top concrete-filled steel tube column 21 is a structure in which concrete is poured outside a steel tube, and the surface of the steel tube is coated with polyaspartic acid resin;

The bottom reinforced concrete column 22 is buried in the ground at a depth of ≥5m. The bottom reinforced concrete column 22 is a structure in which a concrete protective layer is poured on a steel cage. The steel cage is composed of transverse steel bars and longitudinal steel bars arranged in an array. A plurality of longitudinal ribbed steel bars are inserted into the steel cage. The transverse steel bars and the longitudinal steel bars are tied and connected, and the longitudinal steel bar spacing is ≤0.2m, the transverse steel bar layer spacing is ≤0.3m, and the thickness of the concrete protective layer is ≥0.05m.

A steel gasket is placed at the top of the bottom reinforced concrete column 22. A threaded hole is opened at the position of the steel gasket corresponding to the longitudinal ribbed steel bar. The top of the longitudinal ribbed steel bar is threadedly connected to the threaded hole and extends out through the threaded hole. The extended length of the longitudinal ribbed steel bar is 0.5m.

The formula for determining the number of longitudinal ribbed steel bars is as follows:

Wherein, m is the number of longitudinal ribbed steel bars, τ is the bending moment of the prefabricated support column 2, f _y is the yield strength of the longitudinal ribbed steel bars, B _s is the cross-sectional area of the longitudinal ribbed steel bars, h ₀ is the cross-sectional height of the prefabricated support column 2, and a' _s is the thickness of the concrete cover.

A plurality of prestressed anchor cables 5 are evenly fixed to the upper 1/2 section of the cantilever end of the top steel tube concrete column 21, and the plane formed by the plurality of prestressed anchor cables 5 is perpendicular to the plane where the barrier net main body 1 is located;

The total number of prestressed anchor cables 5 is calculated using the following formula:

x＝n/5 (8)

Wherein, x is the total number of prestressed anchor cables 5, and n is the total number of transverse steel strands.

The prestressed anchor cable 5 is anchored in the mountain. The main function of the prestressed anchor cable 5 is to provide resistance for the supporting piles when the collapsed rocks impact the retaining net.

In this embodiment, the total length of the assembled support pile is 13 m, and 10 prestressed anchor cables 5 are arranged from top to bottom, and the spacing between adjacent prestressed anchor cables 5 is 0.8 m.

Construction method:

S1. Install the assembled support column 2:

S11, pouring bottom reinforced concrete column 22:

Based on the arrangement of the assembled support pile array, a pile well is excavated under the mountain, a steel cage is tied in the pile well, and longitudinal ribbed steel bars are inserted into the steel cage. A steel gasket is placed at the top center of the steel cage so that the threaded hole on the steel gasket passes through the longitudinal ribbed steel bars, and then a concrete protective layer is poured;

S21, pouring top steel tube concrete column 21:

First, polyaspartic acid resin is applied to the outside of the steel pipe, and then the steel pipe is placed in the mold for casting;

S22, assembling the bottom reinforced concrete column 22 and the top concrete-filled steel tube column 21:

Place the top steel tube concrete column 21 on the steel gasket, and insert the longitudinal ribbed steel bar into the steel tube, then weld the wing plate on the steel gasket around the top steel tube concrete column 21, and then connect the bottom steel bar concrete with high-strength bolts through the steel gasket;

S2, drilling holes on the mountain slope and placing reverse prestressed anchor cables 4, fixing the tension plate 3 on the mountain slope corresponding to the reverse prestressed anchor cables 4, and then connecting the reverse prestressed anchor cables 4 and one side of the tension plate 3;

S3. Preparation of the barrier net body:

S31, passing the transverse steel strand 11 through the top concrete-filled steel tube column 21 and connecting it to the other side of the tension plate 3;

S32, arranging the longitudinal steel strands 12 along the transverse steel strands 11, and connecting the intersecting transverse steel strands 11 and longitudinal steel strands 12 with fasteners;

S4. Connect the prestressed anchor cable 5 to the top concrete-filled steel tube column 21 and anchor it with the help of a ground beam.

Therefore, the present invention adopts the above-mentioned structure of the assembled barrier net protection structure suitable for the 5000KJ rockfall impact energy level. By setting assembled support columns and using high-strength bolts to connect the top steel tube concrete column and the bottom reinforced concrete column, the bottom reinforced concrete column can be replaced and recycled.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. An assembled barrier net protection structure suitable for 5000KJ rockfall impact energy level, characterized in that it includes a barrier net main body arranged between the hillsides on both sides of the ditch, and a plurality of assembled support columns connected to the barrier net main body at the top, the assembled support columns include a top steel tube concrete column and a bottom reinforced concrete column, the barrier net main body is fixed on the top steel tube concrete column, the bottom end of the top steel tube concrete column is assembled and connected with the top end of the bottom reinforced concrete column through high-strength bolts, and the bottom reinforced concrete column is pre-buried at the bottom of the mountain. 2. According to claim 1, the assembled barrier net protection structure suitable for 5000KJ rockfall impact energy level is characterized in that: the height of the barrier net body is ≥6m, the yield elongation of the barrier net body is ≥0.2%, and the fracture elongation of the barrier net body is ≥20%. 3. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 2 is characterized in that: the barrier net body is a grid structure composed of multiple bundles of transverse steel strands and multiple bundles of longitudinal steel strands crisscrossed, and the transverse steel strands and the longitudinal steel strands are connected by fasteners; Both ends of the transverse steel strands pass through the top steel tube concrete column and are vertically connected to the slopes on both sides of the channel through tension plates and reverse prestressed anchor cables; The materials of transverse steel strands and longitudinal steel strands are both NPR steel. 4. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 3 is characterized in that the spacing between two adjacent bundles of transverse steel strands satisfies the following relationship: Where h is the distance between two adjacent transverse steel strands; n is the number of transverse steel strands; V is the equivalent volume of the rockfall; And the number n of transverse steel strands satisfies the following relationship: MgH≤n(W ₁ +W ₂ ) (2) W ₁ = F ₂ × L × Δ ₁ - F ₁ × L × Δ ₀ (3) W ₂ = F ₂ × L × (Δ ₂ - _{Δ 1} ) (4) Wherein, M is the mass of the rockfall; g is the acceleration of gravity; H is the height difference from the rockfall position to the contact position of the collision impact barrier net body; _W1 is the work done by the single-bundle transverse steel strand in the elastic stage; _W2 is the work done by the single-bundle transverse steel strand in the plastic stage; _F1 is the preload applied to the single-bundle transverse steel strand; _F2 is the yield critical force of the single-bundle transverse steel strand; L is the length of the single-bundle transverse steel strand; _Δ0 is the preload elongation of the single-bundle transverse steel strand; _Δ1 is the yield elongation of the single-bundle transverse steel strand; _Δ2 is the plastic deformation elongation of the single-bundle transverse steel strand. 5. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 3 is characterized in that: the fasteners include T-shaped fasteners and cross-shaped fasteners, and the materials of the T-shaped fasteners and the cross-shaped fasteners are both NPR alloy steel; Wherein, the T-shaped fastener is used to connect the set bundle of transverse steel strands at the top and the intersecting single bundle of vertical steel strands, and the set bundle of transverse steel strands at the bottom and the intersecting single bundle of vertical steel strands; The cross-shaped fastener is used to connect the single bundle of transverse steel strands between the set bundle of transverse steel strands at the top of the connection and the set bundle of transverse steel strands at the bottom and the intersecting single bundle of vertical steel strands; Set the bundle to at least two bundles. 6. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 5 is characterized in that: the T-shaped fastener includes a sleeve for passing through the top set bundle transverse steel strand or the bottom set bundle transverse steel strand, a U-shaped connecting fork ear connected to the sleeve at one end, and a wedge component connected to the other end of the U-shaped connecting fork ear, the wedge component includes a wedge sleeve connected to the outer wall of the U-shaped connecting fork ear through a locking nut at one end, a wedge-shaped hole cavity is provided in the wedge sleeve away from one end of the U-shaped connecting fork ear, a wedge-shaped clamping ring is axially provided in the wedge-shaped hole cavity, and a vertical steel strand is clamped in the wedge clamping ring; the U-shaped connecting fork ear is inserted into the wedge sleeve and then crimped with the wedge clamping ring through a clamping nut, and the clamping nut is also fixedly connected to the outer circumferential side of the vertical steel strand passing through the wedge clamping ring; The cross-shaped fastener includes a base and cover plates which are bolted to the upper and lower ends of the base. A transverse groove and a longitudinal groove are respectively provided between the top end of the base and the corresponding cover plate and between the bottom end of the base and the corresponding cover plate. Transverse steel strands and longitudinal steel strands are respectively engaged in the transverse groove and the longitudinal groove. 7. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 1 is characterized in that: the assembled support column is divided into j equal parts from the top to the bottom according to each section length h ₁ , and the bending moment calculation formula of the assembled support column is as follows: In the formula, τ is the bending moment of the prefabricated support column; E is the elastic modulus of the prefabricated support column; I is the cross-sectional inertia moment of the prefabricated support column; _xk is the horizontal deflection of the k-th prefabricated support column; _xk-1 is the horizontal deflection of the k-1-th prefabricated support column; _xk+1 is the horizontal deflection of the k+1-th prefabricated support column; and k∈(2,j-1). 8. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 7 is characterized in that: a steel pad is arranged between the top steel tube concrete column and the bottom reinforced concrete column, a plurality of wing plates are arranged at the top of the steel pad and around the top steel tube concrete column, the plurality of wing plates enclose a cavity for clamping the plurality of top steel tube concrete columns, and the bottom reinforced concrete column is connected to two adjacent wing plates via high-strength bolts, and the connection between the top steel tube concrete column and the bottom reinforced concrete column is filled with caulking agent; The height ratio of the top steel tube concrete column to the bottom reinforced concrete column is 5:3, and the cross-section of the bottom reinforced concrete column is a square that meets the following requirements: L≥2D (6) Where L is the cross-sectional side length of the bottom reinforced concrete column, and D is the cross-sectional diameter of the top steel tube concrete column; the cross-sectional diameter of the top steel tube concrete column is determined by the finite difference method. 9. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 8 is characterized in that: the top steel tube concrete column is a structure in which concrete is poured outside the steel tube, and the surface of the steel tube is coated with polyaspartic acid resin; The depth of the bottom reinforced concrete column buried in the ground is ≥5m. The bottom reinforced concrete column is a structure with a concrete protective layer poured on a steel cage. The steel cage is composed of transverse steel bars and longitudinal steel bars arranged in an array. Multiple longitudinal ribbed steel bars are inserted in the steel cage. The transverse steel bars and longitudinal steel bars are tied and connected, and the spacing between longitudinal steel bars is ≤0.2m, the spacing between transverse steel bar layers is ≤0.3m, and the thickness of the concrete protective layer is ≥0.05m; A steel gasket is placed at the top of the bottom reinforced concrete column. A threaded hole is opened at the position of the steel gasket corresponding to the longitudinal ribbed steel bar. The top of the longitudinal ribbed steel bar is threadedly connected to the threaded hole and extends out through the threaded hole. The extension length of the longitudinal ribbed steel bar is 0.5m. The formula for determining the number of longitudinal ribbed steel bars is as follows: Where m is the number of longitudinal ribbed steel bars, τ is the bending moment of the prefabricated support column, f _y is the yield strength of the longitudinal ribbed steel bars, B _s is the cross-sectional area of the longitudinal ribbed steel bars, h ₀ is the cross-sectional height of the prefabricated support column, and a' _s is the thickness of the concrete cover. 10. The assembled barrier net protection structure applicable to 5000KJ rockfall impact energy level according to claim 1 is characterized in that: a plurality of prestressed anchor cables are evenly fixed on the top steel tube concrete column from top to bottom, and the plane formed by the plurality of prestressed anchor cables is perpendicular to the plane where the barrier net main body is located; The prestressed anchor cables are anchored on the ground beams, and the ground beams are reversely anchored in the mountain.