Counterfort type filling retaining wall and construction method

Abstract

The invention provides a counterfort type filling retaining wall and a construction method, and the counterfort type filling retaining wall comprises a baffle plate which is detachably arranged at a roadway opening in a blocking manner; the foldable supporting assemblies are arranged on the side, away from the roadway opening, of the baffle at intervals and used for abutting against and supporting the baffle. Each foldable supporting assembly comprises a supporting base, a telescopic supporting frame hinged to the top end of the supporting base and telescopic power, the telescopic end of the telescopic power is hinged to the telescopic supporting frame, and the end, away from the telescopic end, of the telescopic power is connected with the supporting base; the height, away from the hinged end, of the telescopic supporting frame is adjustable, and the telescopic supporting frame is used for abutting against the roadway opening top plate; the sealing layer is arranged on the inner side of the baffle and used for isolating the filling material to prevent the filling material from leaking; the annular air bag is arranged between the roadway opening wall body and the periphery of the baffle and is used for sealing the roadway opening; the construction efficiency can be improved, the construction cost is reduced, and the reliability is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filling mining, and particularly to a counterfort filling retaining wall and a construction method thereof. Background Art

[0002] As a key structure in the filling system, the filling retaining wall undertakes the core functions of enclosing the stope and maintaining the slurry pressure. In the current process, the retaining wall is mostly built with red bricks or concrete at the inlet of the roadway, and its structural dimensions need to be dynamically adjusted according to the roadway section (commonly 2.5×3m to 4×5m), resulting in an average of 3-5 retaining walls of different specifications being built in each stope. Since the stope mining cycle in metal mines has generally been shortened to 7-15 days, the construction frequency of the retaining wall can reach more than 20 times per month. Engineering practice shows that the existing retaining walls have the following technical problems:

[0003] 1. Poor adaptability to special-shaped sections. When encountering trapezoidal or arched roadways, the gap rate between the traditional rectangular retaining wall and the surrounding rock contact surface reaches 15%-20%, resulting in more than 30% loss of the filling body;

[0004] 2. Low construction efficiency. Each retaining wall requires 4-6 workers to work continuously for 12-24 hours (including material transportation, formwork erection, etc.), seriously affecting the mining connection;

[0005] 3. High economic cost. Each single construction consumes 2-3 tons of cement and 8-10 cubic meters of aggregate, and the material transportation cost accounts for 40% of the single project cost;

[0006] 4. Poor structural reliability. The measured data of a copper mine shows that the actual bearing capacity of the retaining wall is only 60%-70% of the design value. In recent years, more than 20 engineering accidents have occurred in the industry every year due to this. For example, a 350 cubic meter slurry leakage occurred in an underground gold mine due to the instability of the retaining wall, resulting in a direct economic loss of 800,000 yuan;

[0007] 5. Difficult to recycle and reuse.

[0008] Therefore, there is an urgent need for a counterfort filling retaining wall and a construction method thereof, which can effectively improve the construction efficiency, reduce the construction cost and improve the reliability. Summary of the Invention

[0009] The purpose of the present invention is to provide a counterfort filling retaining wall and a construction method thereof, aiming to solve the technical problems of long construction period, poor reliability and difficult recycling of traditional filling retaining walls.

[0010] To achieve the above object, in the first aspect, the present invention provides a counterfort filling retaining wall, including:

[0011] A baffle, which is used for detachably blocking the roadway opening;

[0012] A plurality of foldable support components are spaced on the side of the baffle away from the roadway opening for propping and supporting the baffle; each foldable support component includes a support base, a telescopic support frame hinged to the top of the support base, and a telescopic power source. The telescopic end of the telescopic power source is hinged to the telescopic support frame, and the end away from the telescopic end is connected to the support base; the height of the telescopic support frame away from the hinged end is adjustable for abutting against the roof of the roadway opening.

[0013] A sealing layer is provided on the inner side of the baffle for isolating the filling material to prevent its leakage.

[0014] An annular airbag is provided between the wall of the roadway opening and the outer periphery of the baffle for closing the roadway opening.

[0015] As a further improvement of the above solution, the telescopic support frame includes a support plate and a telescopic rod arranged inside the support plate; the fixed end of the telescopic rod is connected to the support plate, and its telescopic end passes through the support plate and extends out of the support plate.

[0016] Preferably, the telescopic rod is a hydraulic cylinder.

[0017] As a further improvement of the above solution, the baffle at least includes two baffle bodies, and the baffle bodies are foldably arranged between each other.

[0018] As a further improvement of the above solution, the baffle is also provided with a water filtering hole for a water filtering pipe to pass through, and one end of the water filtering pipe extends into the filling space, and the other end is exposed outside for permeating the water in the filling material.

[0019] As a further improvement of the above solution, the sealing layer is a geotextile, and the geotextile is fixed to the baffle by screws.

[0020] [[ID=2,4]]As a further improvement of the above solution, the telescopic power source is a hydraulic cylinder.

[0021] As a further improvement of the above solution, the support base includes a bottom plate and a vertical plate fixedly connected to one side of the bottom plate. The bottom plate is used for detachably connecting to the ground of the roadway opening; the top of the vertical plate is hinged to the end of the telescopic support frame away from the telescopic end.

[0022] As a further improvement of the above solution, side grooves are respectively provided on the side of the vertical plate, the side of the telescopic support frame, and the top edge for installing and limiting the annular airbag.

[0023] In a second aspect, the present invention also provides a construction method of a counterfort type filling retaining wall as provided in the first aspect, and its steps include:

[0024] S1. Unfold the baffle and preliminarily fix it at the roadway opening.

[0025] S2. First, arrange several foldable support components at intervals on the side of the baffle away from the roadway entrance. Start the telescopic power to expand the telescopic support frame into a vertical shape and fit it to the outer side of the baffle. Then, extend the telescopic end of the telescopic support frame until it tightly presses against the roof of the roadway entrance.

[0026] S3. Set the sealing layer on the inner side of the baffle, and fix its periphery to the wall of the roadway entrance.

[0027] S4. Place the annular airbag between the wall of the roadway entrance and the outer periphery of the baffle, and pressurize and inflate the annular airbag. Through the extrusion between the annular airbag and the wall and the baffle, seal the roadway entrance.

[0028] As a further improvement of the above solution, between step S2 and step S3, it further includes: detachably fixing the support base to the ground of the roadway entrance, and detachably fixing the baffle to the telescopic support frame.

[0029] Since the present invention adopts the above technical solutions, the beneficial effects of the present application are as follows.

[0030] The present invention provides a counterfort filling retaining wall. Through the extrusion of the annular airbag inflated and pressurized with the baffle and the wall of the roadway entrance, combined with the dynamic adjustment of the support height by the telescopic power in the foldable support component, a closed whole that closely fits the ore and rock at the roadway entrance is formed; not only improves the bearing capacity of the retaining wall (at least by 10%), but also effectively prevents the leakage of filling materials through the coordinated limiting of the annular airbag and the partition plates around the hydraulic support, and the water permeability is increased by more than 10%, significantly enhancing the sealing reliability; the detachable design of the baffle combined with the quick deployment / retraction function of the foldable support component improves the construction efficiency and greatly shortens the construction period; workers only need to operate the telescopic power to adjust the support height, without the assistance of complex machinery, and the labor intensity is significantly reduced; through practical verification, when using a counterfort filling retaining wall provided by the present invention, only two workers can complete the construction of each filling retaining wall in 4 - 5 hours, consuming only a small amount of geotextiles, and the foldable support component, annular airbag and baffle can be recycled 100%, with extremely high economy and convenience; the quick closing ability of the counterfort filling retaining wall provided by the present invention can timely control the risks in the goaf and ensure the safe operation of the mine; its high bearing performance and stability provide reliable technical support for the design and construction of filling mining, and are especially suitable for complex geological environments such as Jinchuan Mining Area, which has important practical significance for improving the filling effect of the goaf and reducing the maintenance cost; in addition, the height-adjustable telescopic support plate, combined with the setting of the sealing layer and the annular airbag, can improve the applicability of the counterfort filling retaining wall. Description of the Drawings

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0032] Figure 1 Stereoscopic schematic diagram of a counterfort filling retaining wall (front) disclosed by the present invention;

[0033] Figure 2 Stereoscopic schematic diagram of the folded state of the foldable support assembly disclosed by the present invention;

[0034] Figure 3 Stereoscopic schematic diagram of the vertically unfolded state of the foldable support assembly disclosed by the present invention;

[0035] Figure 4 Stereoscopic schematic diagram of a counterfort filling retaining wall (back) disclosed by the present invention.

[0036] Reference numerals:

[0037] 1, baffle; 11, baffle body; 2, foldable support assembly; 21, support base; 211, bottom plate; 212, vertical plate; 22, telescopic support frame; 221, support plate; 222, telescopic rod; 23, side groove; 24, telescopic power; 3, sealing layer; 4, annular airbag; 5, filter water pipe.

[0038] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. Specific embodiments

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] It should be noted that all directional indications (such as up, down...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0041] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0042] Moreover, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] Embodiment 1

[0044] Refer to Figures 1-4 , the present invention provides a counterfort filling retaining wall, comprising:

[0045] A baffle 1, used for detachably blocking the roadway opening. Specifically, the baffle 1 includes at least two baffle bodies 11, and the baffle bodies 11 are foldably arranged between each other; in this embodiment, the baffle 1 includes an upper baffle body 11 and a lower baffle body 11 that can be folded up and down, and the upper baffle body 11 and the lower baffle body 11 are foldably arranged through hinges. When unfolded, the outer periphery of the baffle 1 matches the cross-section of the roadway opening and is fixed to the surrounding wall of the roadway opening through detachable bolts; the foldable baffle 1 is convenient for transportation on the one hand, and can be flexibly configured according to the shape of the roadway opening on the other hand. And the foldable support assembly 2 can provide effective support for the baffle arranged at the roadway openings of different heights due to the telescopic support frame 22 with adjustable height.

[0046] A plurality of foldable support assemblies 2, spaced apart on the side of the baffle 1 facing away from the roadway opening, for top-touching and supporting the baffle 1. Preferably, the foldable support assemblies 2 are spaced 3 - 5 groups along the width direction of the baffle 1; each group of the foldable support assemblies 2 includes a support base 21, a telescopic support frame 22 hinged to the top end of the support base 21, and a telescopic power 24. The telescopic end of the telescopic power 24 is hinged to the telescopic support frame 22, and its end away from the telescopic end is connected to the support base 21; the height of the telescopic support frame 22 away from the hinged end is adjustable for top-connecting to the roof of the roadway opening; specifically, the support base 21 is a steel plate base with anchor nails, and the anchor nails are vertically welded to the lower surface of the base and can be inserted into the pre-drilled holes in the roadway floor 211 for positioning; preferably, refer to Figure 2 and Figure 3, the telescopic power 24 adopts a hydraulic cylinder, the cylinder body end of which is connected to the support base 21 through a rotating shaft, and the piston rod end is hinged to the middle of the telescopic support frame 22; when the hydraulic cylinder extends, it pushes the telescopic support frame 22 to unfold in the vertical direction, and when it contracts, it drives the telescopic support frame 22 to fold to a state parallel to the support base 21;

[0047] The sealing layer 3 is arranged inside the baffle 1 and is used to isolate the filling material to prevent its leakage; preferably, the sealing layer 3 is a geotextile, and the geotextile is fixed to the edge of the baffle 1 by screws or pressing strips to form a flexible isolation barrier for the filling material;

[0048] The annular airbag 4, see Figure 4 , is arranged between the wall of the roadway opening and the outer periphery of the baffle 1 and is used to close the roadway opening; specifically, the annular airbag 4 is made of a rubber composite material, is arranged around the outer edge of the baffle 1, the inner side of the annular airbag 4 is fitted with the edge of the foldable support assembly 2 through a side groove 23, and the outer side is temporarily fixed to the wall of the roadway opening through a nylon fastener; the annular airbag 4 is equipped with an independent air valve, and after inflation, it expands to fill the gap between the baffle 1 and the roadway opening, and the working pressure is 0.2 - 0.4 MPa;

[0049] Through the combination of the detachable baffle 1 and the foldable support assembly, the present invention realizes the rapid assembly and disassembly of the retaining wall, and the construction efficiency is increased by more than 60% compared with the traditional masonry retaining wall; the height of the telescopic support frame 22 can be adjusted, and combined with the setting of the foldable support assembly, the foldable support assembly 2 can adapt to roadway openings of various heights, thereby improving the versatility of the counterfort filling retaining wall; in addition, the sealing layer 3 and the inflatable annular airbag 4 form a double sealing system, and it can be tested to withstand a grouting pressure of 0.8 MPa without leakage; all components adopt recyclable materials and standardized interface designs, and a single set of devices can be reused multiple times, and the comprehensive cost is reduced by more than 45%;

[0050] Through the inflation and pressurization of the annular airbag 4 and the extrusion effect between the baffle 1 and the roadway entrance wall, combined with the dynamic adjustment of the support height by the telescopic power 24 in the foldable support assembly 2, a closed whole that closely fits the ore and rock at the roadway entrance is formed; not only the bearing capacity of the retaining wall is improved (at least by 10%), but also through the coordinated limiting of the annular airbag 4 and the partition plates around the hydraulic support, the leakage of the filling material is effectively prevented, and the water permeability is increased by more than 10%, significantly enhancing the sealing reliability; the detachable design of the baffle 1 and the quick unfolding / retracting function of the foldable support assembly 2 improve the construction efficiency and greatly shorten the construction period; workers only need to operate the telescopic power 24 to adjust the support height without the assistance of complex machinery, and the labor intensity is significantly reduced; through practical verification, for a counterfort filling retaining wall provided by the present invention, only two workers can complete the construction of each filling retaining wall in 4 - 5 hours, consuming only a small amount of geotextile, and the foldable support assembly 2, the annular airbag 4 and the baffle 1 can be 100% recycled, with extremely high economy and convenience; the quick closing ability of the counterfort filling retaining wall provided by the present invention can timely control the risk of the goaf and ensure the safe operation of the mine; its high bearing performance and stability provide reliable technical support for the design and construction of filling mining, especially suitable for complex geological environments such as Jinchuan Mining Area, and have important practical significance for improving the filling effect of the goaf and reducing the maintenance cost.

[0051] As a preferred embodiment, the telescopic support frame 22 includes a support plate 221 and a telescopic rod 222 arranged inside the support plate 221; the fixed end of the telescopic rod 222 is connected to the support plate 221, and its telescopic end passes through the support plate 221 and extends out of the support plate 221; specifically, in this embodiment, the telescopic rod 222 is a hydraulic cylinder, a slot hole is arranged on the support plate 221 near the bottom along its height direction, the cylinder body end of the telescopic rod 222 is fixedly connected to the bottom of the slot hole, and a top rod is connected to the piston rod end; a guide hole is correspondingly arranged on the support plate 221 near the top along its height direction, and the top rod passes through the guide hole and extends out of the support plate 221; when the hydraulic cylinder extends, it pushes the top rod to extend vertically to tightly press against the roof of the roadway entrance; the support base 21 at the bottom of the foldable support assembly 2 is tightly connected to the bottom plate 211 of the roadway entrance, and the telescopic support frame 22 at the top is in hydraulic contact connection with the roof of the roadway entrance, so that the foldable support assembly 2 can stably support the baffle 1; during recovery, the telescopic rod 222 retracts, driving the top rod to retract vertically and be received into the guide hole; the telescopic power 24 retracts and then drives the telescopic support frame 22 to fold, and the foldable support assembly 2 in the folded state is convenient for handling and transportation.

[0052] As a preferred embodiment, the baffle 1 is also provided with water filtering holes for the water filtering pipe 5 to pass through. One end of the water filtering pipe 5 extends into the filling space, and the other end is exposed outside, which is used to penetrate the water in the filling material. The setting of the water filtering pipe 5 helps to maintain the stability inside the retaining wall and reduce potential risks caused by problems such as water accumulation.

[0053] As a preferred embodiment, the support base 21 includes a bottom plate 211 and a vertical plate 212 fixedly connected to one side of the bottom plate 211. The bottom plate 211 is used for detachable connection with the ground at the roadway opening; the top end of the vertical plate 212 is hinged to the telescopic support frame 22 away from the telescopic end; preferably, in order to strengthen the strength of the support base 21, the support base 21 further includes a reinforcing rib plate arranged between the bottom plate 211 and the vertical plate 212; a plurality of anchor bolts are provided on the bottom plate 211, which are respectively arranged to match the drill holes on the roadway opening.

[0054] As a preferred embodiment, side grooves 23 are respectively provided on the side of the vertical plate 212, the side of the telescopic support frame 22 and the top edge for installing and defining the annular airbag 4; specifically, the two sides of the vertical plate 212 respectively extend out groove plates, and the side grooves 23 are arranged inside the groove plates; the two sides and the top edge of the support plate 221 of the telescopic support frame 22 respectively extend out the groove plates, and the side grooves 23 are arranged inside the groove plates. The side grooves 23 on the outer periphery of the plurality of foldable support components 2 are correspondingly arranged to form a limiting groove for the annular airbag 4. After the annular airbag 4 is inflated, it expands and presses towards the direction of the roadway wall, so as to effectively fill the gap between the baffle 1 and the roadway opening.

[0055] Embodiment 2

[0056] The present invention also provides a construction method of the counterfort filling retaining wall as described in Embodiment 1, and its steps include:

[0057] S1. Unfold the baffle 1 horizontally along the roadway opening, and realize the preliminary fixation of the baffle 1 and the periphery of the roadway opening through anchor bolts or snap devices to ensure that the plane of the baffle 1 is perpendicular to the roadway axis;

[0058] S2. Arrange a plurality of foldable support components 2 at intervals longitudinally along the roadway outside the baffle 1. Specifically, the foldable support component 2 includes a hinged telescopic support frame 22 and a hydraulic driving device. The telescopic support frame 22 is driven by a telescopic power 24 device to unfold to a vertical state, so that its inner plane is closely attached to the outside of the baffle 1; further, start the vertical telescopic rod 222 (such as a hydraulic cylinder) of the telescopic support frame 22 to make its upper end tightly press against the roadway roof, forming a three-point rigid support system of "roof - support frame - baffle 1";

[0059] S3. Set the sealing layer 3 inside the baffle 1, and fix its periphery to the wall of the roadway opening. Specifically, lay a polymer sealing film inside the baffle 1 as the sealing layer 3. Preferably, a polyurethane composite film is used. Its edge is fixed to the roadway wall surface by expansion bolts, and polysulfide sealant is used for secondary edge sealing treatment to ensure a continuous and airtight interface is formed between the sealing layer 3 and the surrounding rock of the roadway.

[0060] S4. Nest the annular rubber airbag on the outer periphery of the joint between the baffle 1 and the roadway opening, and fill the airbag with 0.3 - 0.5 MPa compressed gas through a high-pressure air pump. During the radial expansion of the annular airbag 4, contact pressure is generated between its inner side and the periphery of the baffle 1, and its outer side and the roadway wall surface, forming an annular sealing belt.

[0061] Through the expandable design of the foldable support assembly 2 and in cooperation with the foldable baffle 1 structure, the present invention can quickly form a stable support system in the roadway section, and the construction efficiency is increased by more than 60% compared with the traditional masonry method. Adopting a "rigid support + flexible seal" composite structure, the foldable support assembly 2 provides stable bearing capacity, and the annular airbag 4 can adapt to the irregular deformation of the roadway wall surface, achieving a sealing qualification rate of ≥98% under a pressure of 0.5 MPa. The support assembly, baffle 1 and airbag all adopt standardized detachable connections, and can be recycled as a whole after the filling operation is completed, and can be used repeatedly, significantly reducing the material loss cost.

[0062] As a preferred embodiment, between step S2 and step S3, it further includes: detachably fixing the support base 21 to the ground of the roadway opening, and detachably fixing the baffle 1 to the telescopic support frame 22; thereby significantly improving the lateral pressure resistance of the overall structure, and the detachable connection method is convenient for subsequent disassembly and repeated recycling.

[0063] The above is only the preferred embodiment of the present invention, and does not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the inventive concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A counterfort filling retaining wall, characterized in that, include: Baffle, used for detachable blocking at the entrance of the tunnel; A plurality of foldable support assemblies are arranged at intervals on the side of the baffle away from the tunnel entrance, and are used to contact and support the baffle; each of the foldable support assemblies includes a support base, a telescopic support frame hinged to the top of the support base, and a telescopic power, the telescopic end of the telescopic power is hinged to the telescopic support frame, and the telescopic end away from the telescopic end is connected to the support base; the height of the telescopic support frame away from the hinged end is adjustable, and is used to contact the top plate of the tunnel entrance; a sealing layer, disposed on the inner side of the baffle, for isolating the filling material to prevent leakage; An annular air bag is arranged between the tunnel entrance wall and the outer periphery of the baffle and is used to close the tunnel entrance.

2. The counterfort filling retaining wall according to claim 1, characterized in that, The telescopic support frame includes a support plate and a telescopic rod arranged in the support plate; the fixed end of the telescopic rod is connected to the support plate, and the telescopic end thereof passes through the support plate and extends out of the support plate.

3. The counterfort filling retaining wall according to claim 1 or 2, characterized in that, The baffle includes at least two baffle bodies, and the baffle bodies are foldable.

4. A counterfort filling retaining wall according to claim 1 or 2, characterized in that, The baffle is also provided with a water filter hole for the water filter pipe to pass through, and one end of the water filter pipe extends into the filling space, and the other end is exposed to the outside for permeating the water in the filling material.

5. The counterfort filling retaining wall according to claim 1 or 2, characterized in that, The sealing layer is a geotextile, and the geotextile is fixed on the baffle.

6. The counterfort filling retaining wall according to claim 2, wherein The telescopic power and the telescopic rod are hydraulic cylinders respectively.

7. The counterfort filling retaining wall according to claim 1 or 2, characterized in that, The support base includes a bottom plate and a vertical plate fixedly connected to one side of the bottom plate, and the bottom plate is used to be detachably connected to the ground of the tunnel entrance; the top end of the vertical plate is hinged to the end of the telescopic support frame away from the telescopic end.

8. The counterfort filling retaining wall according to claim 7, wherein Side edges of the vertical plate, and side edges and top edges of the telescopic support frame are respectively provided with side grooves for installing and limiting the annular airbag.

9. A construction method of a counterfort filling retaining wall according to any one of claims 1-8, characterized in that, The steps include: S1. Expand the baffle and initially fix it at the tunnel entrance; S2. First, several foldable support assemblies are sequentially arranged at intervals on the side of the baffle facing away from the tunnel entrance, and the telescopic power is activated to expand the telescopic support frame into a vertical shape; then, the telescopic end of the telescopic support frame is extended until it presses against the roof of the tunnel entrance; S3, setting a sealing layer on the inner side of the baffle, and fixing its periphery to the wall of the tunnel entrance; S4. Place an annular airbag between the tunnel entrance wall and the outer periphery of the baffle, and pressurize and inflate the annular airbag to close the tunnel entrance through the squeezing effect between the annular airbag, the wall and the baffle.

10. A construction method according to claim 9, characterized in that, Between step S2 and step S3, the method further includes: detachably fixing the support base to the ground at the tunnel entrance, and detachably fixing the baffle to the telescopic support frame.

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