Stilling basin end sill protection structure and construction method

Abstract

A stilling basin end sill protection structure and a construction method, which belong to the technical field of hydraulic and hydropower engineering. The stilling basin end sill protection structure comprises: a stilling basin end sill formed by an original downstream cofferdam, a protection structure on the upstream of the downstream cofferdam, and a protection structure on the downstream of the downstream cofferdam, wherein the protection structure on the upstream of the downstream cofferdam comprises a ground beam arranged at the foot of a slope, multiple layers of gabions stacked on the inner side of the ground beam, a block-stone slope protection located on the back of the gabions, and a gabion protection built by using large block stones after the gabions are stacked at the top of the cofferdam. By means of the protection structure and the construction method, the demolition project volume of the original downstream cofferdam is reduced, and the concrete pouring project volume of the stilling basin end sill is reduced. By means of using the gabions, the block-stone slope protection and mortar-grouted masonry, the stability and impermeability of the protected stilling basin end sill are ensured. The present invention involves convenient and simple operation, and can achieve rapid construction on the premise of ensuring safety and quality. The construction cost is reduced, and the construction period is shortened.

Description

A stilling basin tail sill protection structure and construction method TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy and hydropower engineering, and particularly relates to a stilling basin tail sill protection structure and construction method, which is used in projects with small flow in stilling basins in the fields of water conservancy and hydropower engineering and the like. BACKGROUND

[0002] Generally, in the construction of a hydropower station, after the dam is impounded, the original downstream cofferdam is removed. Before the removal, the construction of the tail sill of the stilling basin needs to be completed. The tail sill of the stilling basin is generally poured with concrete. The conventional tail sill construction of the stilling basin includes the following types.

[0003] (1) Concrete + cushion tail sill: on the basis of the concrete tail sill of the stilling basin, a layer of relatively uniform soil and stone cushion is laid to increase the stability and bearing capacity of the tail sill. The cushion is generally filled with suitable soil, and a suitable filling method can be selected for construction.

[0004] (2) Gravity tail sill: large stone or concrete blocks are used for stacking to form a gravity tail sill. Through the action of gravity, the tail sill is stable, and has certain anti-scouring capacity and durability. This construction method is usually suitable for small-scale tail sills of stilling basins.

[0005] (3) Composite tail sill: a composite tail sill is formed by stacking multiple layers of materials. For example, a certain thickness of gravel layer or impermeable material layer is laid, and then a soil and stone filling layer is laid to increase the stability and drainage performance of the tail sill.

[0006] (4) Notched tail sill: the tail sill of the stilling basin is constructed in sections to form multiple notches, and a certain gap is left between each notch to increase the flow area of the surface of the tail sill, weaken the scouring force of the water flow on the tail sill, and improve the anti-scouring performance of the tail sill.

[0007] (5) Vegetation tail sill: vegetation is covered on the tail sill of the stilling basin, the root system of the vegetation fixes the soil, increases the stability of the soil, and reduces the scouring effect of the water flow on the tail sill. This construction method can improve the ecological environmental benefits of the tail sill, and also has the function of beautifying the landscape.

[0008] (6) Geotextile tail sill: geotextile is laid on the surface of the tail sill of the stilling basin. The geotextile has the ability of tensile strength and dispersion of scouring force. It can effectively inhibit the erosion and shear failure of the soil, and improve the anti-scouring performance of the tail sill.

[0009] (7) Grid toe: Steel wire mesh or synthetic fiber mesh is used to cover the surface of the toe of the stilling basin. Through the reinforcement of the mesh, the stability and carrying capacity of the toe are increased. The mesh can effectively disperse the scouring force and promote the growth of vegetation.

[0010] (8) Concrete reinforced toe: Reinforced concrete is used to reinforce the surface or interior of the toe to increase its resistance to scour and stability. Concrete reinforced toe is generally suitable for large stilling basins or situations where high stability is required.

[0011] (9) Geogrid toe: By installing geogrid in the toe of the stilling basin, the impact force of the water flow can be effectively dispersed and the resistance to scour of the toe can be improved. Geogrid helps to consolidate soil particles and form a stable structure, which can be used for partial or complete reinforcement of the toe.

[0012] Among the above construction types, the downstream cofferdam needs to be removed, and the construction of the toe of the stilling basin needs to be completed; the engineering quantity is large, and the cost is high. In addition, the construction period requirement is also relatively tight, and it is possible that the dam will be impounded after the stilling basin support is not completed, and the downstream cofferdam cannot be removed temporarily.

[0013] In addition, there is no case of using the downstream cofferdam as the toe of the stilling basin. Our company combines the actual engineering demand and fully considers the construction quality, and specially designs a new cofferdam protection form to replace the original design of the concrete toe. Compared with other stilling basin toes at home and abroad, the toe constructed by using this technology can ensure stability and anti-seepage performance (the original downstream cofferdam is provided with a clay core wall and high-pressure jet grouting pile anti-seepage), and at the same time, the technology can also save construction cost and construction period, and has advancement. SUMMARY

[0014] The purpose of the present application is to solve the above-mentioned problems in the prior art, and a stilling basin toe protection structure and a construction method are proposed.

[0015] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0016] A stilling basin toe protection structure, comprising: a stilling basin toe formed by an original downstream cofferdam, and a protection structure on the upstream side of the downstream cofferdam and a protection structure on the downstream side of the downstream cofferdam.

[0017] Among them:

[0018] The protection structure on the upstream side of the downstream cofferdam comprises:

[0019] A ground beam is arranged at the slope toe, a plurality of lead wire cages are arranged inside the ground beam, a block stone slope protection is arranged at the back of the lead wire cage, and a lead wire cage protection is formed by large block stones after the lead wire cage is arranged to the top of the cofferdam;

[0020] The protection structure on the downstream side of the downstream cofferdam comprises a masonry large stone protection.

[0021] Further, the width of the ground beam is 0.5m~1.0m, and the height is 0.5m~1.0m;

[0022] The lead wire cage is staggered up and down by 30~60cm;

[0023] The thickness of the block stone slope protection is 1.0m~1.6m;

[0024] The block stone of the block stone slope protection has a particle size not less than 50cm.

[0025] A construction method of a stilling basin tail sill protection structure, comprising the following steps:

[0026] S1, construction preparation;

[0027] S2, cleaning and trimming;

[0028] The slope foot of the stilling basin and the downstream cofferdam is cleaned;

[0029] S3, ground beam construction;

[0030] The ground beam is arranged at the slope foot, and the length of the ground beam is the same as the length of the downstream cofferdam;

[0031] S4, lead wire cage stacking;

[0032] A row of lead wire cages is first constructed on the inner side of the ground beam, and then another layer of lead wire cages is stacked on the lead wire cages;

[0033] S5, upstream block stone slope protection of the cofferdam;

[0034] After the lead wire cages are stacked for three layers, the block stone slope protection is immediately constructed on the back side of the lead wire cages;

[0035] S6, upstream block stone mortar grouting of the cofferdam;

[0036] After the block stone slope protection is completed, the block stone is mortar grouted;

[0037] S7, lead wire cage stacking to the top of the cofferdam;

[0038] Then, the block stone slope protection is constructed while each layer of lead wire cages is stacked, and the mortar grouting is performed thereafter; in sequence, until the lead wire cage construction is completed;

[0039] S8, large block stone slope protection at the top of the cofferdam;

[0040] After the lead wire cage construction is completed, the width of the original cofferdam top is adjusted and expanded, and the top is protected by large block stones;

[0041] S9, large block stone slope protection at the back of the downstream cofferdam;

[0042] Subsequently, the original cofferdam downstream is protected by large stones with a thickness of 2.0m~3.0m.

[0043] Further, in step S3:

[0044] After the trimming is completed, the cushion concrete is poured first, and then the ground beam construction is performed;

[0045] The cushion concrete is mainly used to fill the local pits and uneven parts that occur during the cleaning process and to level the surface.

[0046] Further, in step S3:

[0047] The bamboo plywood is used for the ground beam formwork, and the bottom of the bamboo plywood is fixed by using the embedded dowel during the pouring of the cushion concrete. The dowel is connected with the steel pipe to form a horizontal surrounding purlin, which is then connected with the vertical steel pipe to form a support system. The topmost part is connected in the upstream and downstream directions by steel pipes, and finally the support system forms a whole.

[0048] Further, in step S3:

[0049] The concrete pouring is performed using the flat layer method;

[0050] Each layer is 30cm high, and pouring is performed from the left bank to the right bank each time until the concrete pouring is completed.

[0051] Further, in step S4:

[0052] Each row of lead wire cages is connected into a whole by steel bars, which are connected by welding. The adjacent lead wire cages are connected by lead wires to ensure that all the lead wire cages are a whole.

[0053] Further, in step S5:

[0054] The stone should be roughly square and have no obvious sharp corners to ensure construction quality and strength;

[0055] During construction, the stones are arranged in a one-order-one-ding manner, and the distance between the middle gaps must be more than 10cm. The contact part between the masonry and the bank slope should be excavated to match the shape of the stone to make the stone and the bank slope tightly combined. The exposed surface of the slope top and side should be selected and laid flat with relatively neat stones.

[0056] Further, in step S5:

[0057] Before masonry begins, measurement and setting out should be performed. Then, from bottom to top, the stones are laid vertically with staggered joints, tightly and compactly, with stable padding, large edge sealing, and a smooth surface. After the masonry is completed, the surface flatness should be checked and necessary trimming should be performed.

[0058] Compared with the prior art, the application provides a stilling basin tail sill protection structure and a construction method, which have the following beneficial effects.

[0059] 1. According to the actual situation on site, the construction method is optimized and adjusted under the premise of guaranteeing the construction quality of tail sill protection, so that the rapid construction of tail sill protection can be realized under the premise of guaranteeing the quality and safety of tail sill protection, which is beneficial to saving the construction period and reducing the project investment.

[0060] 2. The application can guarantee the stability and anti-seepage performance by using the clay core wall and high-pressure rotary jet pile anti-seepage provided by the original downstream cofferdam; meanwhile, the large stones filled during the construction of the original downstream cofferdam are directly used as the protection of the downstream side of the downstream cofferdam, which can save the construction cost and period and has advancement.

[0061] 3. The application has the advantages of simple construction method, easy operation, guarantee of construction quality, acceleration of construction progress, optimization of the original construction method, saving of construction cost, minimization of the influence on the environment and minimization of the influence on environmental pollution.

[0062] 4. The application reduces the amount of downstream cofferdam removal, saves the amount of concrete pouring of the stilling basin tail sill, guarantees the stability and anti-seepage performance of the stilling basin tail sill after protection by using lead wire gabion + block stone slope protection + mortar grouting, realizes rapid construction under the premise of ensuring safety and quality, reduces the construction cost, accelerates the construction speed and saves the construction period through the optimization of the construction process of the stilling basin tail sill protection.

[0063] Other advantages, objects and features of the application will be described in the following description; and to some extent, it will be obvious to those skilled in the art based on the study of the following; or it can be taught from the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0064] Fig. 1 is a schematic view of stilling basin concrete leveling and ground beam.

[0065] Fig. 2 is a schematic view of block stone slope protection and mortar grouting.

[0066] Fig. 3 is a schematic view of three layers of lead wire cage stacking.

[0067] Fig. 4 is a construction method flow chart of the application.

[0068] Fig. 5 is a photo of stilling basin and cofferdam slope foot cleaning.

[0069] Fig. 6 is a ground beam formwork erection drawing.

[0070] Figure 7 is a photo of lead wire cage stacking.

[0071] Figure 8 is a photo of lead wire cage stacking. DETAILED DESCRIPTION

[0072] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments.

[0073] Referring to Figures 1-8, a kind of stilling basin tail sill protection structure and construction method, adopt a new cofferdam protection form to replace the concrete tail sill of original design, downstream cofferdam is used as the tail sill of stilling basin by lead wire stone cage+block stone revetment form, reduce the large amount of earthwork excavation and transportation of original downstream cofferdam, save the concrete amount of original design tail sill, the optimized construction technology and arrangement form can speed up construction progress, save construction period and cost.

[0074] A kind of stilling basin tail sill protection structure includes: the tail sill of stilling basin formed by original downstream cofferdam, and the protection structure of downstream cofferdam upstream side, the protection structure of downstream cofferdam downstream side.

[0075] Wherein:

[0076] The protection structure of downstream cofferdam upstream side includes:

[0077] The ground beam is set in the slope foot, the multiple layers of lead wire cage are stacked in the inside of ground beam, the block stone revetment is located at the back of lead wire cage, and the lead wire cage protection is formed by large block stone masonry after lead wire cage is stacked to the top of cofferdam;

[0078] The protection structure of downstream cofferdam downstream side includes: large block stone protection by mortar masonry.

[0079] By the modification, optimization and protection of original downstream cofferdam, the tail sill of stilling basin is formed;By using combined construction technology, lead wire stone cage+block stone revetment+mortar grouting, the protection of upstream side of downstream cofferdam is formed;At the same time, the large block stone filled during the construction of original downstream cofferdam is directly used as the protection of downstream side of downstream cofferdam, so that the construction period and cost are saved.

[0080] Preferably, the width of the ground beam is 0.5m-1.0m, and the height is 0.5m-1.0m.

[0081] The lead wire cage is staggered up and down by 30-60cm.

[0082] The thickness of the block stone revetment is 1.0m-1.6m.

[0083] The block stone of the block stone revetment has a particle size of not less than 50cm.

[0084] The application discloses a construction method of a baffle structure of a stilling basin tail sill, and comprises the following steps: S1, construction preparation; S2, cleaning and trimming; S3, ground beam construction; S4, lead wire cage stacking; S5, upstream block stone slope protection of a cofferdam; S6, upstream block stone mortar grouting of the cofferdam; S7, lead wire cage stacking to the top of the cofferdam; S8, large block stone slope protection of the top of the cofferdam; and S9, downstream cofferdam back large block stone slope protection.

[0085] S1, construction preparation.

[0086] Before construction, the downstream cofferdam protection drawing is first understood, the actual position and elevation of the cofferdam are checked, and a reasonable ground beam pouring elevation is determined; specifications and quantities of lead wire cages required for tail sill protection are planned in advance, tools, materials and equipment required for construction are prepared, and corresponding technical and site briefings are completed.

[0087] S2, cleaning and trimming.

[0088] The slope foot of the stilling basin and the downstream cofferdam is cleaned; the cleaning position of the downstream cofferdam slope foot is determined according to the drawing, and the ground beam range of the stilling basin and the downstream cofferdam slope foot position is cleaned by using a backhoe, a self-unloading vehicle and manual work.

[0089] The cleaning principle is that surface loose blocks and sundries are removed until the strongly weathered bedrock is cleaned, and then manual cleaning is performed; after the engineer's acceptance is passed, the cushion concrete construction in the slope foot cleaning range is performed.

[0090] S3, ground beam construction.

[0091] After trimming is completed, cushion concrete pouring is first performed, and then ground beam construction is performed; the ground beam is arranged at the slope foot, the length of the ground beam is the same as the length of the downstream cofferdam, the width of the ground beam is 0.5m to 1.0m, and the height of the ground beam is 0.5m to 1.0m.

[0092] Specifically,

[0093] After cleaning is completed, cushion concrete pouring is first performed on the cleaned part of the slope foot; the cushion concrete is C15 concrete with a strength, and concrete tankers and backhoes are used for concrete storage; the cushion concrete is mainly used for backfilling local pits and uneven parts in the cleaning process, and is used for leveling; during concrete pouring, a 50mm diameter vibrating rod is used for vibrating the concrete.

[0094] After the cushion concrete pouring is completed and reaches a certain strength, ground beam construction is prepared to be started.

[0095] The existing bamboo plywood on site is used as the formwork of the ground beam, and the damaged parts are repaired. The bottom of the bamboo plywood is fixed by using the embedded reinforcing bars during the pouring of the cushion concrete, and the reinforcing bars are connected with the steel pipes to form the transverse purlins. Then, the transverse purlins are connected with the vertical steel pipes to form the support system. The spacing between the vertical steel pipes is 1.0 m, and the spacing between the transverse steel pipes is 0.5 m. The topmost part is connected with the steel pipes in the upstream and downstream directions, and finally the support system forms a whole.

[0096] The concrete tank truck + chute is used for pouring the concrete of the ground beam, and the concrete strength is C25 concrete. During the pouring of the concrete, a 50 mm diameter vibrating rod is used for vibrating. The concrete is poured by using the flat layer method, and the height of each layer is 30 cm. The pouring is performed from the left bank to the right bank each time until the pouring of the concrete is completed.

[0097] S4, the wire mesh is stacked.

[0098] A row of wire mesh (length * width * height) with a size of 2.0 m * 1.0 m * 1.0 m is first constructed on the inside of the ground beam, and then another layer of wire mesh is stacked on the wire mesh. The wire mesh is staggered by 30-60 cm in height, and preferably by 50 cm.

[0099] Each row of wire mesh is connected into a whole by using steel bars. The steel bars have a diameter of 20 mm and a length of 9.0 m. The steel bars are connected by welding, and the adjacent wire meshes are connected by wire to ensure that all the wire meshes are a whole.

[0100] Specifically:

[0101] After the pouring of the concrete ground beam is completed, a layer of wire stone cage with a width of 2.0 m is arranged behind the ground beam. Then, the second layer of wire stone cage is arranged above the wire stone cage at the bottom. The second layer of wire stone cage is staggered with the first layer of wire stone cage, and each time it is offset by 50 cm in the downstream direction to form a slope of 1:0.5. The specific arrangement is shown in FIG. 3.

[0102] Construction points of the wire mesh stacking:

[0103] Firstly, the foundation of the construction area should be flat and solid to withstand the weight of the wire mesh. The material of the wire mesh should have sufficient strength and durability, and the diameter and mesh size of the wire should meet the design requirements. The wire mesh should be accurately made, the mesh size should be uniform, and the wire joints should be firm to ensure the stability during use.

[0104] When stacking the wire mesh, it should be done according to the design requirements, from bottom to top and from inside to outside. Ensure that each layer of wire mesh is stably placed on the next layer, and at the same time, a certain space should be reserved for stability and fixation. In order to prevent the wire mesh from shifting or falling during construction, appropriate fixation measures should be taken.

[0105] S5, upstream block stone revetment of cofferdam.

[0106] After the lead wire cage is stacked three layers, immediately start the block stone revetment construction on the back side of the lead wire cage; the thickness of the block stone revetment is 0.8m-1.5m; the block stone particle size is not less than 50cm.

[0107] The construction points of block stone revetment:

[0108] The stone should be roughly square, and the surface should not have obvious sharp corners to ensure construction quality and strength; during construction, arrange in the way of one order and one inch, and the distance of the middle gap must be more than 10cm; the contact part of the masonry and the bank slope should be excavated into a shape suitable for the block stone, so that the block stone is combined closely with the bank slope; the top and side of the exposed surface of the masonry should be laid with relatively neat stone blocks.

[0109] Before construction, measurement and setting out should be carried out; then from bottom to top, vertically laid with staggered joints, tightly and densely, with pad stability, large block edge sealing, and smooth surface; after construction, the surface flatness should be checked and necessary trimming should be carried out.

[0110] S6, block stone mortar grouting of upstream cofferdam.

[0111] After the completion of the block stone revetment, the block stone is grouted with mortar.

[0112] Specifically: after the lead wire cage is stacked three layers, immediately grout the block stone revetment on the slope surface with mortar to ensure the close combination of mortar and block stone.

[0113] The construction points of mortar grouting:

[0114] Ensure that the quality of stone and mortar meets the requirements, and the mix proportion of mortar should be verified by test to ensure that its strength and durability meet the design requirements;

[0115] Clean and level the construction foundation and meet the construction requirements;

[0116] According to the design drawings and requirements, lay the stone on the foundation in order to ensure that the stone is flat, stable, and the gap between the stones is controlled;

[0117] According to the mix proportion requirements, mix the mortar materials to ensure that the uniformity and consistency of the mortar meet the requirements;

[0118] Grout the mixed mortar into the gap between the stones to ensure that the mortar is dense and has no voids; at the same time, pay attention to control the thickness and uniformity of the mortar;

[0119] After the mortar grouting is completed, the surface is treated to ensure that the surface is flat, smooth, and has no obvious color difference and defects;

[0120] After the construction is completed, maintenance is carried out, and quality detection is carried out according to relevant standards and specifications, so that the construction quality meets the requirements;

[0121] During the construction process, safety measures should be implemented, such as wearing safety helmets, gloves and other protective equipment, to avoid injuries caused by improper operation or material splashing.

[0122] S7, the lead wire cage is placed on the top of the cofferdam.

[0123] After that, the block stone revetment is constructed while each layer of lead wire cage is placed, and then mortar is poured; in turn, until the lead wire cage construction is completed.

[0124] S8, the block stone revetment on the top of the cofferdam.

[0125] After the lead wire cage construction is completed, the original cofferdam top width is adjusted and expanded to 6.0m wide, and the top is protected by block stone.

[0126] Specifically: when the lead wire cage is placed on the top of the cofferdam, 2.0m thick block stone is constructed on the top of the cofferdam to form protection for the lead wire cage. The block stone protection construction points are as described above.

[0127] S9, the block stone revetment on the back of the downstream cofferdam.

[0128] Then, the original downstream cofferdam is protected by block stone, and the block stone thickness is 2.0m~3.0m;

[0129] Specifically: the backwater surface protection of the downstream cofferdam adopts 2.0m thick block stone, and after the block stone construction is completed, mortar is poured to form protection for the backwater surface of the cofferdam. The mortar pouring points are as described above.

[0130] According to the actual situation on site, the construction method is optimized and adjusted in combination with the domestic and foreign built and already built stilling basin sill protection cases under the premise of ensuring that the construction quality meets the requirements, so that the rapid construction of the sill protection can be realized under the premise of ensuring the quality and safety of the sill protection, which is beneficial to save the construction period and reduce the engineering investment. Moreover, the clay core wall and high-pressure jet grouting pile anti-seepage provided by the original downstream cofferdam can ensure the stability and anti-seepage performance; at the same time, the block stone filled during the construction of the original downstream cofferdam is directly used as the protection of the downstream side of the downstream cofferdam, which can also save the construction cost and period, and has advancement.

[0131] The present application is particularly suitable for the protection of the stilling basin sill with small flow, and has the following remarkable effects:

[0132] (1) The construction method is simple and easy to operate;

[0133] (2) The construction quality can be ensured, and the construction progress can be accelerated;

[0134] (3) Optimized the original construction method, saving construction cost;

[0135] (4) Minimize the impact on the environment;

[0136] (5) Minimize the impact on the environment pollution.

[0137] (6) Reduce the original downstream cofferdam demolition work;

[0138] (7) Save the concrete pouring amount of the stilling basin tail sill;

[0139] (8) The lead wire stone cage + block stone slope protection + mortar grouting is adopted to ensure the stability and impermeability of the stilling basin tail sill protection;

[0140] (9) Easy and simple operation, fast construction under the premise of safety and quality;

[0141] (10) Through the process optimization of the stilling basin tail sill protection construction, the construction cost is reduced, the construction speed is accelerated, and the construction period is saved.

[0142] The downstream cofferdam of Zambia Nkaya Fu Gorge Hydropower Station Project is 69.7m long along the axis, 12.0m wide at the top, and the downstream cofferdam is considered for twenty-year flood during construction period; the corresponding upstream cofferdam water level is 467.5m, and considering a certain safety superhigh distance, the upstream cofferdam top elevation is 469.0m. The downstream cofferdam below EL463.0m adopts high-pressure jet grouting anti-seepage, EL463.0m~EL464.5m along the axis direction pours concrete, and above EL464.5m adopts geomembrane + earthwork backfill anti-seepage, the downstream cofferdam water surface slope ratio is 1:1.75, and the backwater surface slope ratio is 1:1.5, and the geomembrane on both sides is respectively transition material I area and transition material II area, wherein the transition material I area width is 4.0m, and the transition material II area upstream and downstream width is 3.0m each; the transition material I area requires backfill soil and stone particle size less than 10cm.

[0143] According to the original design drawings, the downstream cofferdam will be removed after the dam is impounded; since the stilling basin support has not been completed after the dam is impounded, the downstream cofferdam cannot be removed temporarily, and only after the completion of the stilling basin support, the concrete tail sill is set at the end of the stilling basin to protect the stilling basin. After repeated communication with the consulting engineer and the owner, it is finally determined to repair the downstream cofferdam again, and the downstream cofferdam is protected to replace the stilling basin tail sill, and the original design of the stilling basin concrete tail sill is not constructed.

[0144] After design optimization, the original concrete tail sill was optimized to downstream cofferdam + wire mesh cage protection + stone slope protection + mortar grouting, avoiding the demolition of the original downstream cofferdam and concrete pouring; specifically, after the energy dismantling pool was cleaned, the loose body at the bottom was cleaned with a backhoe at the position determined after measurement and layout on the upstream side of the downstream cofferdam near the slope foot, and then a concrete leveling layer was poured at the bottom, and then a concrete retaining sill was poured at the front, with a height of 50 cm and a width of 50 cm. Finally, a wire mesh gabion was used as a retaining guard.

[0145] The use of wire mesh cages in place of the original concrete tail sill reduced project construction costs and time, resolving issues encountered during the concrete tail sill construction process. The design and construction methods of the wire mesh cages used in the downstream cofferdam were also improved, ensuring their quality. This achievement was also successfully applied to the construction of the downstream cofferdam at the Julius Nyerere Hydropower Station in Tanzania, where the resulting protection was well-received by the client and consulting engineers.

[0146] The present invention has produced great economic benefits, and the specific economic benefits are as follows.

[0147] (1) 3,000 cubic meters of reinforced concrete and 150 tons of steel bars at the end of the energy dissipation pool were eliminated, saving RMB 750,000 in steel bar construction costs and RMB 300,000 in concrete construction costs.

[0148] (2) Eliminate the excavation and transportation of 100,000 cubic meters of original earth and stone for the downstream cofferdam, saving RMB 3 million in construction costs.

[0149] (3) Using this method to protect the downstream cofferdam, the cost of the wire mesh cage was RMB 300,000, and the cost of the stone slope protection + mortar grouting was RMB 600,000. The specific economic benefits generated were RMB 750,000 + RMB 300,000 + RMB 300,000 - RMB 300,000 - RMB 600,000 = RMB 3.15 million, which is a significant economic benefit. At the same time, the owner expressed recognition of the new technology adopted by the company and gave high praise to this construction process.

[0150] The present invention has produced great social benefits.

[0151] The successful application of this method at the Lower Kafue Gorge Hydropower Station in Zambia and the Julius Nyerere Hydropower Station in Tanzania has proven that it not only reduces construction costs and schedules, but also ensures the quality and effectiveness of downstream cofferdam protection. Strict adherence to this method during construction has achieved both quality standards and timelines, saving costs and achieving excellent results. This has been recognized and praised by the client and consultants, and has provided over 200 jobs for the local government.

[0152] The performance of this patent is good.

[0153] After the dam is impounded, the stilling basin is constructed after impoundment, which is different from the previous construction process and construction method, the method of the patent is used for stilling basin tail sill protection, under the premise of not affecting normal power generation, the stilling basin tail sill protection is successfully completed, and good project performance is realized.

[0154] The stilling basin tail sill protection constructed by the technology of the application has good effect through engineering practice application, and the technology is worth using in the water conservancy and hydropower engineering and the power engineering of the stilling basin with small flow.

[0155] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the application within the technical range disclosed by the application, which should be covered in the protection scope of the application.

[0156] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, the person skilled in the art can combine and combine the different embodiments or features of the embodiments or examples described in the present specification without contradiction.

[0157] Although the embodiments of the application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the application, and the person skilled in the art can change, modify, replace and modify the above embodiments within the scope of the application.

Claims

1. A stilling pool tail sill protection structure, characterized in that: include: The tail sill of the stilling pool formed by the original downstream cofferdam, as well as the protective structure on the upstream side of the downstream cofferdam and the protective structure on the downstream side of the downstream cofferdam; in: The protective structure on the upstream side of the downstream cofferdam includes: The ground beams at the foot of the slope, the multi-layered wire mesh cages stacked inside the ground beams, the stone slope protection behind the wire mesh cages, and the wire mesh cage protection formed by large stone masonry after the wire mesh cages are stacked to the top of the cofferdam; The protective structure on the downstream side of the downstream cofferdam includes: large stone masonry protection.

2. The stilling pool tail sill protection structure according to claim 1 is characterized in that: The width of the ground beam is 0.5m~1.0m, and the height is 0.5m~1.0m; The wire cages are staggered 30 to 60 cm up and down; The thickness of the block stone slope protection is 1.0m~1.6m; The particle size of the blocks of stone slope protection is not less than 50cm.

3. A construction method for the stilling pool tail sill protection structure according to claim 1 or 2, characterized in that: The following steps are involved: S1. Construction preparation; S2, cleaning and trimming; Clean the stilling basin and the toe of the downstream cofferdam; S3, ground beam construction; Set up a ground beam at the foot of the slope, and the length of the ground beam should be the same as the length of the downstream cofferdam; S4, stacking wire cages; First construct a row of wire cages on the inner side of the ground beam, and then stack another layer of wire cages on top of the wire cages; S5, stone slope protection upstream of the cofferdam; After the wire mesh cages are stacked in three layers, the stone slope protection will be constructed immediately behind the wire mesh cages. S6, grouting of block stone mortar upstream of the cofferdam; After the stone slope protection is completed, the stone blocks are mortared; S7. Stack the wire cages on top of the cofferdam; Afterwards, while stacking each layer of wire mesh cage, stone slope protection is constructed, and then mortar is poured; and so on, until the wire mesh cage construction is completed; S8, large stone slope protection at the top of the cofferdam; After the wire mesh cage construction is completed, the width of the original cofferdam top is adjusted and expanded, and large stones are used for protection on the top; S9, large stone slope protection on the back of downstream cofferdam; Subsequently, the downstream of the original cofferdam was protected with large stones with a thickness of 2.0m~3.0m.

4. The construction method of the stilling pool tail sill protection structure according to claim 3 is characterized in that: In step S3: After the finishing is completed, the cushion concrete is poured first, followed by the ground beam construction; The cushion concrete is mainly used to backfill the local pits and uneven areas that appear during the cleaning process, and the cushion concrete is used for leveling.

5. The construction method of the stilling pool tail sill protection structure according to claim 3 or 4, characterized in that: In step S3: The ground beam formwork is made of bamboo plywood, and the bottom of the bamboo plywood is fixed by embedded rebars in the downstream during the pouring of the cushion concrete. The rebars are connected to the steel pipes to form horizontal purlins, which are then connected to the vertical steel pipes to form a support system; the top is connected with steel pipes in the upstream and downstream directions, finally making the support system a whole.

6. The construction method of the stilling pool tail sill protection structure according to claim 5 is characterized in that: In step S3: Concrete pouring is carried out using the flat layer method; Each layer is 30cm high and is poured from the left bank to the right bank until the concrete pouring is completed.

7. The construction method of the stilling pool tail sill protection structure according to claim 3 is characterized in that: In step S4: Each row of wire mesh cages is connected into a whole by steel bars. The steel bars are connected by welding, and adjacent wire mesh cages are connected by wire to ensure that all wire mesh cages are a whole.

8. The construction method of the stilling pool tail sill protection structure according to claim 3 is characterized in that: In step S5: The stone should be roughly square, with no obvious sharp corners on the surface to ensure construction quality and strength; During the construction process, the masonry should be arranged in a one-by-one manner, and the distance between the gaps must be more than 10 cm; the contact between the masonry and the slope should be excavated into a suitable stone shape so that the stone blocks are tightly combined with the slope; the exposed top and sides of the masonry should be built flat with relatively neat stones.

9. The construction method of the stilling pool tail sill protection structure according to claim 3 or 8, characterized in that: In step S5: Before the masonry begins, measurements and layout must be carried out; then from bottom to top, vertical masonry should be carried out with staggered joints, close and dense, padding should be firm, large blocks should be sealed at the edges, and the surface should be leveled; after the masonry is completed, the surface flatness should be checked and necessary adjustments should be made.

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