Compound overwater cofferdam structure and filling process thereof

Abstract

The application belongs to the technical field of hydraulic engineering construction, and provides a composite water passing cofferdam structure, which comprises: a main body filled on a riverbed in the direction of cutting off water flow and combined with mountain bodies on both sides of the riverbed; the main body is filled with cemented sand and gravel (CSG) material, the thickness of the main body gradually decreases from the bottom to the top in a trapezoidal shape, and the main body has a first slope surface on the upstream side and a second slope surface on the downstream side; a cushion layer filled below the main body and extended to the bedrock position below the riverbed; a first impermeable layer filled along the first slope surface of the main body; and a prefabricated block template used for being detachably installed on the second slope surface of the main body; the application can realize efficient, safe and high-quality dam construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic engineering construction, in particular to a composite water-passing cofferdam structure and a filling process thereof. BACKGROUND

[0002] In the hydraulic engineering, a water-passing cofferdam is usually built in the dry season, and the normal construction of the engineering in the cofferdam or downstream is protected during this period. Generally, in the flood season, the water flow in the river increases and gradually climbs along the water-facing slope (the slope surface on the upstream side of the cofferdam), and finally submerges the top of the water-passing cofferdam.

[0003] CSG (Cemented Sand and Gravel) cofferdam technology is a new type of dam building technology. The core of this technology is to add a small amount of cementing material and water to the riverbed sand and gravel or excavated waste, and then use simple stirring to obtain the filling material, which can be regarded as a poor cemented sand and gravel material. It has been proved by practice that the CSG cofferdam has great advantages in safety, construction period and environmental protection.

[0004] However, when filling the CSG cofferdam, not only the river valley needs to be excavated and the accumulated water in the foundation pit needs to be pumped out in advance for the later pouring of concrete, but also various forms need to be erected during the filling process to overcome the lateral pressure of the CSG material during the rolling construction. Therefore, the construction period of the CSG cofferdam is affected by many factors, and it is difficult to efficiently and safely complete the cofferdam construction. SUMMARY

[0005] In view of the defects in the prior art, the present application provides a composite water-passing cofferdam structure and a filling process thereof, which can realize efficient, safe and high-quality dam building.

[0006] A composite water-passing cofferdam structure, comprising:

[0007] a main body filled on the riverbed in the direction of cutting off the water flow and combined with the mountains on both sides of the riverbed; the main body is filled with CSG material, the thickness of the main body gradually decreases from the bottom to the top in a trapezoidal shape, and has a first slope surface on the upstream side and a second slope surface on the downstream side;

[0008] a cushion layer filled below the main body and extending to the bedrock position below the riverbed;

[0009] a first impermeable layer filled along the first slope surface of the main body; and

[0010] a prefabricated block formwork for detachably mounting on the second slope surface of the main body.

[0011] Preferably, a rockfill support body is filled at the high and steep slope where the main body is combined with the riverbed side mountain, the rockfill support body comprising a rockfill body and self-compacting concrete poured into the rockfill body.

[0012] Preferably, a layer of stone residue is filled along the upstream side of the first impermeable layer.

[0013] A filling process of a composite water passing cofferdam, comprising the following steps:

[0014] A cutoff dike is filled on the upstream side of the cofferdam;

[0015] Water chasing concrete is poured in the area of the cofferdam for drainage, and the water chasing concrete forms a cushion layer and connects with the riverbed bedrock after solidification;

[0016] A first layer of prefabricated block template is installed on the downstream side of the cofferdam main body, CSG material matching the height of the prefabricated block template is filled in the area of the cofferdam main body, and a first impermeable layer is formed by synchronously backfilling the first impermeable material on the upstream side of the cofferdam main body, and the cofferdam is constructed in layers from bottom to top according to the foregoing steps.

[0017] Preferably, the step of pouring water chasing concrete in the area of the cofferdam for drainage specifically comprises:

[0018] The area of the cofferdam is surrounded by sandbags, and a drainage port is formed;

[0019] The water chasing concrete is continuously poured into the surrounded area away from the low-lying place of the drainage port, so that the accumulated water in the surrounded area is drained from the drainage port.

[0020] Preferably, the step of surrounding the area of the cofferdam by sandbags and forming a drainage port specifically comprises:

[0021] The area of the cofferdam is surrounded by sandbags in sections along the direction of river water flow, and each section of the surrounded area of the cofferdam has a drainage port formed by the sandbags.

[0022] Preferably, the step of continuously pouring the water chasing concrete into the surrounded area away from the low-lying place of the drainage port so that the accumulated water in the surrounded area is drained from the drainage port specifically comprises:

[0023] The water chasing concrete is poured along the side away from the drainage port to form a water chasing slope surface;

[0024] The newly poured water chasing concrete is squeezed into the already poured water chasing concrete, and the water chasing slope surface is pushed towards the drainage port to push the accumulated water along the drainage port.

[0025] Preferably, before the main body of the cofferdam is filled to the steep section on the side of the riverbed, the method further includes:

[0026] The boulders are naturally piled into the warehouse at the high and steep slope where the cofferdam meets the side of the riverbed and the mountain, so as to form a boulders body with gaps.

[0027] Self-compacting concrete is poured into the voids of the riprap to form a riprap support.

[0028] Preferably, after the step of installing the first layer of precast retaining block templates on the downstream side of the cofferdam body, and before the step of filling the area of ​​the cofferdam body with CSG material matching the height of the precast retaining block templates, the method further includes:

[0029] The second seepage-proof material is filled between the prefabricated retaining block template and the downstream side of the cofferdam body to form a second seepage-proof layer.

[0030] Preferably, after the step of simultaneously backfilling the first impermeable material on the upstream side of the cofferdam body to form the first impermeable layer, the method further includes:

[0031] Between the first impermeable layer and the embankment, stone chips are backfilled synchronously as the number of the first impermeable layer increases to form a stone chip layer.

[0032] The beneficial effects of this invention are as follows:

[0033] The construction of the main body, the bedding layer, and the first anti-seepage layer ensures the stability of the cofferdam structure and prevents water seepage at the bottom of the cofferdam. The precast retaining block formwork uses its own weight to resist the lateral pressure of the CSG material on the precast retaining block formwork during the compaction process, which not only eliminates the need for an additional formwork support system, saving construction time and reducing project costs, but also makes the precast retaining block formwork easy to install and disassemble, and allows for flexible placement of the entry points, facilitating efficient and multi-point entry of CSG material.

[0034] By setting up a drainage system using water-repelling concrete, the water is gradually driven out of the cofferdam construction area by its own weight. This solves the problems of difficult and time-consuming drainage of the foundation pit, further shortens the pouring time, and efficiently forms the foundation layer of the cofferdam, increasing its stability.

[0035] By simultaneously backfilling the first anti-seepage material, the interference of the formwork preparation and lifting of the formwork with the pouring of the cofferdam surface on the upstream side of the main body is eliminated, which speeds up the construction progress and saves manpower and equipment. Moreover, vehicles can enter the cofferdam at any point along the entire cofferdam, saving the time of sealing and finishing. It also saves the amount of upstream GERCC (roller-compacted concrete) work and the time for excavating and transporting slag from the dam foundation pit, further shortening the construction cycle and achieving efficient cofferdam construction. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or prior art will be briefly introduced below. In all the drawings, the elements or parts are not necessarily drawn to scale.

[0037] Figure 1 This is a cross-sectional view of the water-passing cofferdam in this invention;

[0038] Figure 2 This is a longitudinal section view of the cofferdam used in this invention;

[0039] Figure 3 This is a flowchart of the filling process of the cofferdam in this invention;

[0040] Figure label:

[0041] 1-Main body, 11-Self-collapse;

[0042] 2-Subbase layer;

[0043] 3-First impermeable layer;

[0044] 4-Precast stop block template;

[0045] 5-Rockfill support structure;

[0046] 6-Stone ballast layer, 61-General fill layer, 62-Excavated fill layer;

[0047] 7-Second impermeable layer;

[0048] 8-Third impermeable layer;

[0049] 9 - Original boundary line;

[0050] 10-Rockfill Protective Structure. Detailed Implementation

[0051] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0052] Please see Figure 1 A composite water-passing cofferdam structure includes a main body 1, a cushion layer 2, a first seepage-proof layer 3, and a prefabricated retaining block template 4.

[0053] The main body 1 is constructed on the riverbed along the direction of the intercepted water flow and is integrated with the mountains on both sides of the riverbed. The main body 1 is constructed using CSG (cemented sand and gravel) material. The thickness of the main body 1 gradually decreases from bottom to top, forming a trapezoidal shape, and it has a first slope on the upstream side and a second slope on the downstream side. Specifically, the slope ratio of the first slope is greater than that of the second slope. It is understood that CSG material is made by adding cementing materials to sand and gravel, which increases the cohesive strength of the sand and gravel, thereby optimizing the structure of the main body 1 of the cofferdam, strengthening its stability, reducing the heat of hydration and temperature stress of cement, lowering the probability of crack formation, and preventing water from entering the cofferdam along the compacted weak surfaces. In this embodiment, the slope ratio of the first slope is 1:0.5, and the slope ratio of the second slope is 1:0.7.

[0054] Please refer to it again. Figure 1 and Figure 2 In one embodiment, a rockfill support 5 is constructed at the steep section where the main body 1 connects to the riverbed side mountain. The rockfill support 5 includes a rockfill body and self-consolidating concrete (SCC) poured within the rockfill body. It is understood that steep sections of the mountain are inconvenient for material placement and increase the time required for transporting materials into the placement area. If conventional pumped concrete is used, the heat of hydration cannot be effectively controlled, easily leading to concrete cracking and wasting costs and materials. Therefore, by placing boulders or pebbles at the steep section to form a rockfill body, and then pouring self-consolidating concrete within the rockfill body, the rockfill support 5 is formed. This facilitates material placement, and the steep section is already completed when the main body 1 of the cofferdam reaches this position, thus shortening the construction period.

[0055] In one embodiment, a self-collapsing dike 11 is constructed on the top of the main body 1 along the direction in which the main body 1 blocks the water flow. Specifically, the self-collapsing dike 11 is constructed of earth and rock, and when floodwaters overflow the self-collapsing dike 11, the self-collapsing dike 11 will self-destruct, thereby improving the safety of the cofferdam during water passage.

[0056] In one embodiment, a third impermeable layer 8 is constructed between the top of the main body 1 and the self-collapse dike 11. Specifically, the third impermeable layer 8 can be constructed using conventional machine-mixed GERCC material, thereby improving the impermeability of the cofferdam.

[0057] The subbase 2 is constructed below the main body 1 and extends to the bedrock below the riverbed. Specifically, the subbase 2 is constructed using water-repellent concrete. In this embodiment, the slope ratio of the upstream and downstream sides of the subbase 2 is 1:1.5.

[0058] The first impermeable layer 3 is constructed along the first slope of the main body 1. Specifically, the first impermeable layer 3 can be made of clay, which can be firmly adsorbed on the upstream side of the main body 1 to prevent water from entering the main body 1, and its raw materials are readily available and low in cost.

[0059] In one embodiment, a stone slag layer 6 is constructed along the upstream side of the first impermeable layer 3. The stone slag layer 6 is a sloping surface inclined towards the first impermeable layer 3 and abuts against the intercepting dike. Specifically, the stone slag layer 6 includes a general fill layer 61 and an excavated fill layer 62, wherein the general fill is placed between the first impermeable layer 3 and the excavated fill layer 62. It is understood that the general fill layer 61 uses conventional filling materials used in hydraulic engineering, while the excavated fill layer 62 uses materials excavated on-site, thereby saving costs, reducing material transportation time, and reducing excavation waste, further improving efficiency and shortening the construction period. The slope ratio of the interface between the general fill layer 61 and the first impermeable layer 3 is greater than the slope ratio of the interface between the excavated fill layer 62 and the general fill layer 61. The slope inclination of the second impermeable layer 7, the general fill layer, and the excavated fill layer gradually decreases, and the upstream side of the excavated fill layer abuts the intercepting dike. The slope ratio of the interface between the general fill layer 61 and the first impermeable layer 3 is 1:1, and the slope ratio of the interface between the excavated fill layer 62 and the general fill layer 61 is 1:1.5.

[0060] The precast retaining block template 4 is detachably installed on the second slope of the main body 1. Specifically, the precast retaining block template 4 is made of concrete and is a cuboid with dimensions consistent with the dimensions of the spillway steps behind the dam. This allows the precast retaining block template to be used in the dam construction after the cofferdam is completed, effectively improving the reusability of the precast retaining block template 4 and reducing costs. Therefore, in this embodiment, the precast retaining block template 4 can be 1.2m × 0.8m × 1m (height × thickness × width). It is understood that the self-weight of the precast retaining block template 4 can resist the lateral pressure on it during the CSG material compaction process, eliminating the need for a separate template support system and reducing project costs. Furthermore, the precast retaining block template 4 is easy to install and disassemble, allowing for flexible placement of the entry points, thus facilitating efficient and multi-point entry of CSG material.

[0061] In one embodiment, the prefabricated block template 4 is arranged in a multi-step manner from bottom to top along the second slope of the downstream side of the main body 1.

[0062] In one embodiment, riprap is filled in the lower-middle part of the downstream side of the precast retaining block template 4 to form a riprap protection body 10. Specifically, the riprap protection body 10 is provided to increase the stability of the precast retaining block template 4, thereby resisting the lateral pressure during the pouring and compaction of the cofferdam body 1.

[0063] In one embodiment, the cofferdam further includes a second seepage barrier layer 7, which is filled between the downstream side of the main body 1 and the precast retaining block template 4. Specifically, in this embodiment, the second seepage barrier layer 7 can be made of a slurry-rich material, thereby enhancing the overall seepage prevention capability of the cofferdam.

[0064] Please see Figure 3 The present invention also provides a filling process for a composite cofferdam, which can construct the aforementioned composite cofferdam structure. Specifically, the filling process includes the following steps:

[0065] S1: Construct a diversion embankment on the upstream side of the cofferdam.

[0066] A dam is a permeable weir spanning a river, constructed by dumping precast concrete blocks and locally sourced fill materials into the flowing water during the damming construction of water conservancy and hydropower projects. Understandably, damming weirs can be constructed using conventional damming methods to cut off the river and prevent river water from interfering with the construction of the cofferdam.

[0067] S2: Drainage is carried out by pouring water-repelling concrete within the cofferdam area. After the water-repelling concrete solidifies, it forms cushion layer 2 and connects with the bedrock of the riverbed.

[0068] Specifically, before construction of the cofferdam upstream of the dam, it was difficult to pump out the accumulated water from the riverbed at the bottom of the cofferdam area. Conventional methods, such as excavating to the bedrock below the riverbed and then completely pumping the water out, would take considerable time. Furthermore, the cofferdam pit contained a large body of water, making it difficult to pump out the accumulated water in a timely manner. Therefore, pouring water-repelling concrete was chosen, utilizing the concrete's own weight to drain the water from the construction area, thus significantly shortening the construction period.

[0069] In one embodiment, the step of pouring water-repelling concrete within the cofferdam area for drainage specifically includes: enclosing the cofferdam area with sandbags to form a drainage outlet; and continuously pouring water-repelling concrete to a low-lying area away from the drainage outlet in the enclosed area so that the accumulated water in the enclosed area can be discharged from the drainage outlet.

[0070] In one embodiment, the step of enclosing the cofferdam area with sandbags and forming a drainage outlet specifically includes: enclosing the cofferdam area in sections along the direction of river flow with sandbags, and each enclosed section of the cofferdam area has a drainage outlet formed by sandbags.

[0071] Specifically, the cofferdam area can be divided into sections based on its actual conditions (such as area size and water volume). This embodiment employs a three-stage drainage system: first, sandbags are used to enclose approximately one-third of the cofferdam area. Then, the pump end is inserted into the underwater low-lying area, and water-driving concrete is continuously pumped, systematically driving the accumulated water from the side of the enclosed area furthest from the sandbag drainage outlet towards the sandbag outlet. Finally, the water flows out from the sandbag drainage outlet. The same method is then used to drain the remaining sections of the enclosed cofferdam area, excluding the aforementioned one-third section. Furthermore, the water-driving concrete is poured 8 to 10 meters deep into the riverbed, exceeding the water level in the foundation pit during construction.

[0072] Specifically, when using sandbags for containment, there will inevitably be gaps between the sandbags. These gaps allow water to flow through but not the water-repelling concrete, thus forming drainage outlets. It's understandable that when using sandbags for containment, certain gaps can be left to form drainage outlets, allowing large amounts of accumulated water to drain out. Then, before the water-repelling concrete reaches these outlets, sandbags are used to promptly block these gaps, reducing the volume of the drainage outlets and preventing the water-repelling concrete from being lost.

[0073] In one embodiment, the step of continuously pouring water-repelling concrete to a low-lying area away from the drainage outlet within the enclosed area to drain the accumulated water from the drainage outlet specifically includes: pouring water-repelling concrete along the side away from the drainage outlet to form a water-repelling slope; squeezing newly poured concrete into the already poured concrete and pushing the water-repelling slope towards the drainage outlet to drive the accumulated water out through the drainage outlet. It is understood that this embodiment utilizes the weight of the water-repelling concrete to gradually drive the accumulated water out of the cofferdam area.

[0074] Specifically, the newly poured water-repelling concrete is squeezed into the already poured water-repelling concrete using a vibration method, thereby ensuring that only the water-repelling slope is in direct contact with the water; and the already poured water-repelling concrete cannot solidify before the pouring of the foundation layer 2 is completed, so as not to affect its drainage effect.

[0075] In one embodiment, the slump of the water-repellent concrete is between 120mm and 160mm. Specifically, to improve the workability and pumpability of the water-repellent concrete, the final mix proportion of the water-repellent concrete in this embodiment was selected based on the results of multiple sets of indoor mix proportion tests. The water-cement ratio of the water-repellent concrete is 0.6, the design strength is C15, and the sand ratio is 45%. The dosage of each material in the water-repellent concrete (kg / m³) 3 The composition is as follows: water 200; cement 333; compacted sand 795; small aggregate 583; medium aggregate 389; water-reducing agent 3.33. See the table below for details:

[0076]

[0077] Step S3: Install the first layer of precast retaining block template 4 on the downstream side of the main body of the cofferdam 1; then fill the area of ​​the main body of the cofferdam with CSG material that matches the height of the precast retaining block template 4, and simultaneously backfill the first anti-seepage material on the upstream side of the main body of the cofferdam to form the first anti-seepage layer 3; construct the cofferdam layer by layer from bottom to top according to the aforementioned steps.

[0078] Specifically, precast retaining block templates 4 are laid layer by layer along the downstream side of the cofferdam body 1, in the direction of water flow interception. Then, CSG material is filled into the cofferdam body 1 and compacted layer by layer. In this embodiment, the height of each layer of precast retaining block templates 4 is 1.2m, and the compaction thickness of each layer of CSG material is 600mm. Therefore, two layers of CSG material need to be compacted for each layer of precast retaining block templates 4 laid, facilitating quality control of the CSG compaction layer thickness. This allows the CSG material compartments within the cofferdam body 1 to be constructed layer by layer from bottom to top along the downstream side of the cofferdam body 1, along with the precast retaining block templates 4; and the downstream side of the cofferdam body 1 gradually narrows inward from low to high, ultimately resulting in a multi-step shape on the downstream side of the cofferdam body 1.

[0079] In one embodiment, before the step of installing the first layer of prefabricated retaining block template 4 on the downstream side of the cofferdam body 1, the method further includes: laying a layer of plastic isolation cloth on the downstream side of the cofferdam body 1.

[0080] Specifically, the plastic isolation cloth can not only prevent the second seepage prevention material from leaking from the precast retaining block template 4 during the filling process, but also facilitate the disassembly of the precast retaining block template 4 after the cofferdam construction is completed so that it can be reused (such as for the later construction of the dam).

[0081] In one embodiment, after the step of installing the first layer of prefabricated retaining block template 4 on the downstream side of the cofferdam body 1 and before the step of filling the area of ​​the cofferdam body 1 with CSG material that matches the height of the prefabricated retaining block template 4, the method further includes: filling the downstream side of the cofferdam body 1 and the prefabricated retaining block template 4 with a second seepage-proof material.

[0082] Specifically, the second seepage-proof material is conventional machine-mixed GERCC, which is low in cost and further improves the seepage-proof capability of the cofferdam.

[0083] In one embodiment, the step of filling the area of ​​the cofferdam body 1 with CSG material that matches the height of the precast retaining block template 4 specifically includes: pouring CSG material into the cofferdam body 1, and then spreading, vibrating and compacting it layer by layer.

[0084] Specifically, this implementation method employs a layer-by-layer paving and vibration compaction process during construction, eliminating the anisotropy of seepage and significantly improving the overall seepage resistance of the cofferdam body 1. Each compacted layer is controlled to be approximately 600mm thick. From the initial elevation of the CSG material at EL60m to the crest elevation at EL88.3m, a total of 48 layers are paved and compacted, with a total elevation increase of 28.3m. Furthermore, to reduce transportation time and ensure the quality of the CSG material, centralized mixing of the CSG material is carried out on a platform located close to the cofferdam, with an open area and convenient transportation.

[0085] In one embodiment, the first seepage-proof material can be clay. In this embodiment, since the upstream side of the cofferdam is close to the intercepting dike, the first seepage-proof material is filled between the intercepting dike and the main body of the cofferdam 1 to achieve seepage prevention on the upstream side of the cofferdam. Specifically, during construction, as the CSG material compartment number increases, the first seepage-proof layer 3 (clay seepage-proof layer) is backfilled and compacted simultaneously. Since no formwork is erected on the upstream face, both CSG material and clay can be placed at multiple points, improving placement efficiency. At the same time, because the time for erecting formwork on the upstream face is reduced, and the multi-point placement method is adopted, the construction efficiency is improved, resulting in a significant increase in the CSG cofferdam filling speed and further shortening the construction cycle.

[0086] In one embodiment, after the step of synchronously backfilling the first seepage-proof material on the upstream side of the cofferdam body 1 to form the first seepage-proof layer, the method further includes: between the first seepage-proof layer 3 and the levee, synchronously backfilling stone chips to form a stone chip layer 6 as the number of the first seepage-proof layer 3 increases.

[0087] Specifically, the rockfill layer 6 includes a general fill layer 61 and an excavated fill layer 62, with the general fill layer 61 constructed along the first anti-seepage layer 3 and the excavated fill layer 62 constructed along the general fill layer 61. This further enhances the anti-seepage capacity of the upstream side of the cofferdam.

[0088] Please see Figure 2 and Figure 3 In one embodiment, before the main body of the cofferdam 1 is filled to the steep section on the side of the riverbed, the method further includes: naturally piling up boulders (or pebbles) into the storage area to the steep slope where the cofferdam and the mountain on the side of the riverbed meet, so as to form a hollow rockfill body; and pouring self-compacting concrete (SCC) into the gaps in the rockfill body to form a rockfill support 5.

[0089] Understandably, by utilizing the high fluidity, filling performance, and anti-segregation properties of self-compacting concrete, it fills the voids in the rockfill body under its own weight, forming a complete, dense, and low-heat-of-hydration large-volume concrete, thereby saving costs and material usage. The mix proportions for self-compacting concrete (SCC) are: water-cement ratio 0.6, design strength C15, design slump spread 120mm~160mm, maximum aggregate size 45mm; material usage (kg / m³) is as follows. 3 ): Water 200; Cement 333; Washed sand 795; Small stones 583; Water-reducing agent 3.33. Details are shown in the table below:

[0090]

[0091] Specifically, the rockfill body and the self-compacting concrete (SCC) pouring location are located above EL80.0m. Before the valley excavation or before the main body of the cofferdam 1 reached this location, the rockfill support 5 was built to support it, ensuring the timely pouring of CSG material for the main body of the cofferdam 1; the multi-point synchronous construction of the cofferdam shortened the construction cycle.

[0092] In one embodiment, after completing the steps of filling the main body 1 with CSG material and related compaction construction, the method further includes filling the top of the main body 1 with a third seepage-proof material to form a third seepage-proof layer 8.

[0093] Specifically, the third impermeable material can be conventional machine-mixed material GERCC.

[0094] In one embodiment, after completing the filling step of the third impermeable layer 8, the method further includes filling soil and rock material onto the top of the third impermeable layer 8 to form a self-collapse dam 11.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A composite cofferdam structure, characterized in that, include: The main body is filled into the riverbed along the direction of the cut-off water flow and is combined with the mountains on both sides of the riverbed; the main body is filled with CSG material, and the thickness of the main body gradually decreases from bottom to top in a trapezoidal shape, and has a first slope on the upstream side and a second slope on the downstream side; A cushion layer, which is filled below the main body and extends to the bedrock below the riverbed; The first impermeable layer is constructed along the first slope of the main body; and Prefabricated stop block templates are used for detachable installation on the second slope of the main body; A rockfill support structure is constructed at the steep slope where the main body connects with the side mountain of the riverbed. The rockfill support structure includes a rockfill body and self-compacting concrete poured into the rockfill body.

2. The composite cofferdam structure according to claim 1, characterized in that, A layer of stone chips is filled along the upstream side of the first impermeable layer.

3. A filling process for a composite cofferdam, used to construct a composite cofferdam structure as described in claim 1, characterized in that, Includes the following steps: Construct a diversion embankment on the upstream side of the cofferdam; Within the cofferdam area, water-repelling concrete is poured to drain water. After the water-repelling concrete solidifies, it forms a cushion layer and connects with the bedrock of the riverbed. Install the first layer of prefabricated retaining block template on the downstream side of the main body of the cofferdam, fill the area of ​​the main body of the cofferdam with CSG material that matches the height of the prefabricated retaining block template, and simultaneously backfill the first seepage prevention material on the upstream side of the main body of the cofferdam to form the first seepage prevention layer. Construct the cofferdam layer by layer from bottom to top according to the aforementioned steps.

4. The filling process of a composite cofferdam according to claim 3, characterized in that, The step of pouring water-repelling concrete within the cofferdam area for drainage specifically includes: The area of ​​the cofferdam was enclosed with sandbags to form a drainage outlet; The water-repelling concrete is continuously poured into a low-lying area away from the drain outlet in the enclosed area to drain the accumulated water in the enclosed area from the drain outlet.

5. The filling process of a composite cofferdam according to claim 4, characterized in that, The step of enclosing the cofferdam area with sandbags and forming a drainage outlet specifically includes: Along the direction of the river flow, the cofferdam area is divided into sections by sandbags, and each section of the cofferdam area has a drainage outlet formed by the sandbags.

6. The filling process of a composite cofferdam according to claim 4, characterized in that, The step of continuously pouring the water-repelling concrete into a low-lying area away from the drain outlet within the enclosed area to drain the accumulated water from the drain outlet specifically includes: The water-repelling concrete is poured along the side away from the drain outlet to form a water-repelling slope. The newly poured water-repelling concrete is squeezed into the already poured water-repelling concrete, and the water-repelling slope is pushed to move towards the drain outlet to push the accumulated water out along the drain outlet.

7. The filling process of a composite cofferdam according to claim 3, characterized in that, Before the main body of the cofferdam is filled to the steep section on the side of the riverbed, it also includes: The boulders are naturally piled into the warehouse at the high and steep slope where the cofferdam meets the side of the riverbed and the mountain, so as to form a boulders body with gaps. Self-compacting concrete is poured into the voids of the riprap to form a riprap support.

8. The filling process of a composite cofferdam according to claim 3, characterized in that, After the step of installing the first layer of precast retaining block templates on the downstream side of the main body of the cofferdam, and before the step of filling the area of ​​the main body of the cofferdam with CSG material that matches the height of the precast retaining block templates, the method further includes: The second seepage-proof material is filled between the prefabricated retaining block template and the downstream side of the cofferdam body to form a second seepage-proof layer.

9. The filling process of a composite cofferdam according to claim 3, characterized in that, After the step of simultaneously backfilling the first seepage-proof material on the upstream side of the main body of the cofferdam to form the first seepage-proof layer, the method further includes: Between the first impermeable layer and the embankment, stone chips are backfilled synchronously as the number of the first impermeable layer increases to form a stone chip layer.

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