A preparation method of an erosion-resistant layer based on a frozen mass

Abstract

The present invention discloses a preparation method of an anti-scouring layer based on frozen blocks, belonging to the technical field of engineering structure construction and reinforcement. The specific operation is as follows: put frozen bonding material blocks before initial setting to level the pits on the underwater riverbed, and then put frozen bonding material blocks after initial setting on the frozen bonding material blocks before initial setting as a stable reinforcement layer. By adopting this method, a scouring-resistant layer can be prepared at the underwater scoured part to reduce the scouring effect of subsequent water flow and improve the service life of the building.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering structure construction and reinforcement, and particularly relates to a preparation method of an erosion-resistant layer based on frozen blocks. Background Art

[0002] At present, China's construction industry is in a stage of rapid development, and various underwater concrete structures emerge in an endless stream. Among them, the erosion problems to be faced are becoming increasingly prominent. Erosion refers to the process in which water flow erodes sediments and other substances around structures such as riverbeds, embankments, and bridge foundations. It is affected by various hydrological conditions such as water depth, flow direction, and flow velocity, as well as environmental factors such as foundation form and sediment characteristics. Its main forms include natural evolution erosion, general erosion, local erosion, etc. Erosion will not only reduce the effective embedment depth of underwater concrete structures, but even erode the foundation of underwater concrete structures, increasing the risk of structural failure. Taking bridge piers as an example, horseshoe flow and downflow are the main problems in the formation of erosion holes around bridge piers. Due to turbulent fluctuations and water flow acceleration, sediment will be entrained and transported, which will lead to a reduction in the embedment depth of bridge piers and insufficient bearing capacity.

[0003] In existing research, anti-erosion devices have been reported, including active protection measures and passive protection measures. Among them, active protection measures include guard ring protection, ring-wing bridge piers, pier slotting protection, sacrificial pile protection in front of piers, etc. Active protection measures require cumbersome construction processes and high costs. Usually, measures are taken during the construction period, and long-term erosion problems will still be faced after forming; while passive protection measures have relatively simple construction processes and can be adopted throughout the entire life cycle of the structure. Passive protection measures include riprap protection, sand quilt and sandbag protection, solidified soil protection, etc. However, riprap protection will cause riprap shear failure and edge failure problems, sand quilt and sandbag protection are easily scoured and emptied, and solidified soil protection will have the phenomenon of loss of reinforcement materials. The defects of such passive methods are mainly because it is impossible to form a firmly bonded whole of reinforcement materials such as riprap, sand quilt and sandbag, and solidified soil around the underwater concrete structure, and their loose structures may even cause further damage to the underwater concrete structure.

[0004] Therefore, in order to improve the defect that passive protection measures cannot form a firm whole, it is urgent to design a fast, effective, safe and reliable reinforcement technical solution to ensure the long-term safety of underwater concrete structures. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the present invention provides a preparation method of an erosion-resistant layer based on frozen blocks. By using this method, an erosion-resistant layer can be prepared at the underwater eroded part to reduce the subsequent erosion effect of water flow and improve the service life of the building.

[0006] To achieve the above object, the technical solution adopted by the present invention to solve its technical problems is:

[0007] A preparation method of an erosion-resistant layer based on frozen blocks is to put frozen binder material blocks before initial setting to level the pits on the underwater riverbed, and then put frozen binder material blocks after initial setting on the frozen binder material blocks before initial setting as a stable reinforcement layer.

[0008] In the above solution, first add frozen binder material blocks before initial setting into the pits on the underwater riverbed to fill the pits; then add frozen blocks after initial setting. The strength of the added frozen concrete blocks after initial setting is relatively low and will not damage the underwater part of the building; and after the blocks in this part thaw, they will also partially disperse to fill the gaps between the upper-layer blocks and the surface layer of the frozen blocks before initial setting, providing a protective layer and reducing the erosion of water flow.

[0009] Further, the preparation method of the frozen binder material blocks before initial setting is: place the binder material in a frozen environment for freezing treatment before initial setting, so that the binder material forms a block with the outside frozen into a solid state and the inside being liquid, that is, the frozen binder material blocks before initial setting are obtained.

[0010] Further, the preparation method of the frozen binder material blocks after initial setting is: place the binder material in a frozen environment for freezing treatment after initial setting, so that the binder material forms a block with the whole being frozen, that is, the frozen binder material blocks after initial setting are obtained.

[0011] Further, the volume of the frozen binder material blocks after initial setting is larger than the volume of the frozen binder material blocks before initial setting.

[0012] Further, the preparation raw materials of the frozen binder material blocks before initial setting and the frozen binder material blocks after initial setting are the same.

[0013] Further, the raw materials of the frozen blocks include cement, sand, gravel, water reducer, flocculant and water; the mass ratio of the cement: sand: gravel: water = 400 - 450: 150 - 200: 1000 - 1500, and the water reducer and the flocculant respectively account for 0.5 - 5% of the weight of the cement.

[0014] Further, among the gravel, the crushed stones of 5 - 10 mm account for 30 - 50% of the total amount of the gravel, and the crushed stones of 10 - 20 mm account for 50 - 70% of the total amount of the gravel.

[0015] Further, the raw materials of the frozen blocks include red clay, organic soil solidifying agent, water reducer and flocculant, and the mass ratio of the red clay to the organic soil solidifying agent is 2 - 4: 1, and the water reducer and the flocculant respectively account for 0.5 - 5% of the total weight of the organic soil solidifying agent.

[0016] Further, the organic soil solidifying agent is STW polymer.

[0017] The beneficial effects produced by the present invention are:

[0018] The present invention utilizes the plasticizing ability of the frozen bonded material block after thawing in water. By adding admixtures, its bonding ability after thawing is increased, and a protective layer is formed around the underwater concrete structure to reduce the scouring effect of water flow.

[0019] The beneficial effects of the frozen bonded material block are manifested in the following three aspects: First, it has bondability and can form an integral protective layer around the underwater concrete structure, without worrying about the risks of breaking up and reducing the burial depth, providing long-term and effective anti-scouring protection for the underwater concrete structure; Second, frozen blocks with smaller volumes and good gradations can be prepared, and there is no damage to the underwater concrete structure caused by large-scale mechanical equipment and large-volume rock blocks during the construction process; Finally, frozen blocks of different sizes and shapes can be made according to the riverbed topography to fill the pits formed by scouring as much as possible.

[0020] Therefore, the present invention ingeniously eliminates the destructive effect of scouring on the underwater concrete structure and the riverbed with frozen blocks, effectively playing a role in protecting the underwater concrete structure. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the operation process of the present invention;

[0022] Figure 2 It is a statistical chart of the performance of the frozen bonded material block before initial setting at different freezing intervention times;

[0023] Figure 3 It is a statistical chart of the performance of non-frozen concrete;

[0024] Figure 4 It is a statistical chart of the mass loss rate of different blocks after falling into the water;

[0025] Figure 5 It is a statistical chart of the mass loss rate of the drop hammer of different blocks after 1 day;

[0026] Figure 6 It is a statistical chart of the mass loss rate of the drop hammer of frozen concrete blocks in different forms;

[0027] Figure 7 It is a statistical chart of the mass loss rate of filling materials under different filling forms and different water flow velocities;

[0028] Figure 8 It is a schematic diagram of the filling form in the present invention. Detailed Embodiment

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0030] Therefore, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0031] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0032] The features and performance of the present invention will be further described in detail below in conjunction with embodiments and drawings.

[0033] Example 1

[0034] A preparation method of an erosion-resistant layer based on frozen blocks, wherein the bonding material is concrete, and its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of gravel, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass of 5-10 mm crushed stone accounts for 40% of the total amount of gravel, the mass of 10-20 mm crushed stone accounts for 60% of the total amount of gravel, and the water-binder ratio is 0.42.

[0035] The above concrete is frozen at -40°C for 5 minutes 8 hours before initial setting to form a block with a frozen solid exterior and a liquid interior, that is, a concrete block frozen before initial setting is obtained.

[0036] Using the above method, the concrete cooling intervention time is sequentially extended to 6 hours, 4 hours, and 2 hours before initial setting, and the freezing operation is repeated to prepare concrete blocks frozen before initial setting with different freezing intervention times.

[0037] Example 2

[0038] A preparation method of an erosion-resistant layer based on frozen blocks, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of stones, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5-10 mm gravel to the total amount of stones is 40%, the mass ratio of 10-20 mm gravel to the total amount of stones is 60%, and the water-binder ratio is 0.42;

[0039] Freeze the above concrete for 5 minutes at -40°C 4 hours before initial setting to form a block with the outside frozen into a solid state and the inside in a liquid state, that is, obtain a concrete block frozen before initial setting.

[0040] Example 3

[0041] A preparation method of an erosion-resistant layer based on frozen blocks, with the bonding material being undisturbed red clay. Its raw materials are made by mixing red clay and soil stabilizer STW polymer in a mass ratio of 3:1, and adding 1% of polycarboxylate superplasticizer and 1% of UWB-II type flocculant based on the mass of the soil stabilizer. The water-soil ratio is 0.42;

[0042] Freeze the solidified soil for 5 minutes at -40°C 4 hours after its preparation is completed, so that the bonding material forms a block with the outside frozen into a solid state and the inside in a liquid state, that is, obtain a red clay block frozen before initial setting.

[0043] Example 4

[0044] A preparation method of an erosion-resistant layer based on frozen blocks, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of stones, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5-10 mm gravel to the total amount of stones is 40%, the mass ratio of 10-20 mm gravel to the total amount of stones is 60%, and the water-binder ratio is 0.42. Prepare a solid mold;

[0045] Freeze the concrete for 5 minutes at -40°C 4 hours before initial setting, so that the bonding material forms a block with the outside frozen into a solid state and the inside in a liquid state, that is, obtain a concrete block frozen before initial setting;

[0046] Put the frozen concrete block into the prepared 300 mm 3 mold and make it solidify into a whole to prepare a concrete block.

[0047] In addition, make the concrete into a nominal particle size of 50 mm 3of gravel-like and 100mm 3 cubes.

[0048] Example 5

[0049] A preparation method of an anti-scouring layer based on frozen blocks, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of gravel, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5 - 10 mm gravel to the total amount of gravel is 40%, the mass ratio of 10 - 20 mm gravel to the total amount of gravel is 60%, and the water-binder ratio is 0.42;

[0050] The concrete 4 hours before initial setting and the concrete 2 hours after initial setting are respectively frozen for 5 minutes under the freezing condition of -40°C. The concrete 4 hours before initial setting is made into gravel-like with a nominal diameter greater than 50 mm. At the same time, a mold with corresponding length, width, and height of 150 mm is prepared, and a steel wire is passed through the middle of the mold. The frozen block after initial setting is placed in the mold to form a whole by solidifying it, and the frozen block after initial setting is obtained; then the frozen block before initial setting is laid on the underwater bottom pit. After paving the pit, the frozen block after initial setting is put on it until it reaches one-third of the lower part of the bridge pier.

[0051] Example 6

[0052] A preparation method of an anti-scouring layer based on frozen blocks, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of gravel, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5 - 10 mm gravel to the total amount of gravel is 40%, the mass ratio of 10 - 20 mm gravel to the total amount of gravel is 60%, and the water-binder ratio is 0.42;

[0053] The concrete 4 hours before initial setting is frozen for 5 minutes under the freezing condition of -40°C and made into gravel-like with a nominal diameter greater than 50 mm. At the same time, a mold with corresponding length, width, and height of 150 mm is prepared, and a steel wire is passed through the middle of the mold. Part of the frozen block before initial setting is placed in the mold to form a whole block by solidifying it; the frozen gravel-like block before initial setting is laid on the bottom pit. After paving the pit, the frozen block solidified before initial setting is put on it until it reaches one-third of the lower part of the bridge pier.

[0054] Example 7

[0055] A preparation method of an erosion-resistant layer based on frozen blocks, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of gravel, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5 - 10 mm gravel in the total gravel is 40%, the mass ratio of 10 - 20 mm gravel in the total gravel is 60%, and the water-binder ratio is 0.42;

[0056] Freeze the concrete 2 hours after initial setting under the freezing condition of -40°C for 5 minutes, and make it into gravel shape with a nominal diameter greater than 50 mm. At the same time, prepare a mold with corresponding length, width and height of 150 mm, and penetrate the mold with steel wires in the middle. Place some of the frozen blocks after initial setting into the mold to make it solidify into a whole block; Lay the frozen gravel-shaped blocks after initial setting at the bottom pit. After leveling the pit, put the frozen blocks solidified after initial setting on it until reaching one-third of the lower part of the bridge pier.

[0057] Comparative Example 1

[0058] A preparation method of an erosion-resistant layer, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of gravel, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5 - 10 mm gravel in the total gravel is 40%, the mass ratio of 10 - 20 mm gravel in the total gravel is 60%, and the water-binder ratio is 0.42.

[0059] Comparative Example 2

[0060] A preparation method of an erosion-resistant layer based on frozen blocks, with the bonding material being undisturbed red clay. Its raw materials are made by mixing red clay and soil curing agent STW polymer in a mass ratio of 3:1, and adding 1% of polycarboxylate superplasticizer and 1% of UWB-II type flocculant based on the mass of the curing agent, and the water-soil ratio is 0.42.

[0061] Comparative Example 3

[0062] A preparation method of an erosion-resistant layer, with the bonding material being undisturbed red clay. Its raw materials are made by mixing red clay and soil curing agent STW polymer in a mass ratio of 3:1, and the water-soil ratio is 0.42.

[0063] Comparative Example 4

[0064] A preparation method of an erosion-resistant layer based on frozen blocks, with the bonding material being concrete. Its raw materials include 430 kg of cement, 172 kg of water, 1320 kg of gravel, 528 kg of sand, 4.3 kg of polycarboxylate water reducer, and 4.3 kg of UWB-II type flocculant. Among them, the mass ratio of 5-10 mm gravel in the total amount of gravel is 40%, the mass ratio of 10-20 mm gravel in the total amount of gravel is 60%, and the water-binder ratio is 0.42;

[0065] Pour the concrete 4 hours before initial setting into the wire mesh, freeze it for 5 minutes under the freezing condition of -40°C, and then throw the concrete blocks in the fiber mesh around the underwater pit. After thawing, a ring of concrete protective layer is formed.

[0066] Experimental Example

[0067] I. Taking the concrete formula in Example 1 as an example, measure the performance of the frozen concrete blocks with the cooling intervention time of 8 h, 6 h, 4 h, and 2 h respectively. The specific test operations are as follows:

[0068] (1) Test the suspended solid content. Specifically: Divide 500 g of representative frozen blocks into 10 parts, slowly put them into a 1000 ml beaker containing 800 ml of deionized water at room temperature, let it stand for 1 hour. After the blocks thaw, use a glass pipette to gently suck 600 ml of water from the water surface of the beaker within 1 minute. Among them, 200 ml is used for the determination of the pH value by a pH meter; the remaining samples are put into a Buchner funnel equipped with a glass fiber filter paper. After vacuum filtration, the filter paper is repeatedly dried at 110°C for 1 h until constant weight, until the mass difference between two weighings is not more than 0.4 mg. Then, measure the mass change of the filter paper before and after filtration, and convert it into mg / L according to a volume of 400 ml as the suspended solid content;

[0069] (2) Test the cement loss. Specifically: Place a container with a volume of 1500 mL at the bottom of the bucket, fill the bucket with water to a height of 500 mm. Take 2 kg of the frozen blocks, let them freely fall from the water surface and sink completely into the container in the water. Let it stand for 1 h. After the frozen blocks thaw, lift the container out of the water, drain the water remaining on the surface of the concrete, and calculate its mass loss rate as the cement loss. Test it twice and take the average value.

[0070] (3) Measure the stability and bonding performance, and test its bonded splitting tensile strength and pore water absorption rate with reference to the test code for hydraulic concrete: Split three groups of frozen 150-mm cube specimens into six pieces after soaking them in water for 14 days for forming. Clean the split surfaces and keep them moist, then vertically place them on one side of a 150-mm cube mold, with the smooth surface closely attached to the inner wall of the mold, and a remaining space with dimensions of approximately 150 mm × 75 mm × 150 mm is formed between the split surface and the mold. In the remaining space of the six molds, place newly frozen 150-mm × 75-mm × 150-mm blocks and compact them. After 1 day, conduct a splitting tensile strength test at a rate of 2.0 MPa / min. After discarding the maximum and minimum values among the six groups, the average value is taken to obtain the bonded splitting tensile strength; Place the frozen 150-mm cube blocks in water for 2 hours, weigh the mass difference before and after soaking, and use the water absorption rate as an index to evaluate the pore water absorption rate of the blocks.

[0071] (4) Measure the mass loss rate, specifically: Gently drop the material into a 300-mm cube mold from a water surface with a height of 500 mm. After 1 day, take it out of the water, demold it, and conduct a repeated drop hammer experiment. Use a 1-kg drop hammer to continuously drop from a height of 50 cm to test the mass loss rate of the block, so as to characterize the bonding stability of the material.

[0072] The specific results of the above operations are shown in Figure 2 and Table 1, Figure 2 which is a statistical chart of the performance of the bonded material blocks frozen before initial setting under different freezing intervention times;

[0073] Table 1:

[0074]

[0075] Taking the concrete formula in Example 1 as an example, cancel the operation of freezing the concrete (the technical solution in Comparative Example 1), and then at 8 h, 6 h, 4 h, and 2 h before initial setting of the concrete, use the above method to test the performance of the concrete in water. The specific results are shown in Figure 3 and Table 1; Figure 3 which is a statistical chart of the performance of the unfrozen concrete;

[0076] Through Figure 2 - 3It can be seen from the data in Table 1 that when the temperature is lowered and frozen 4 hours before the initial setting, the anti-dispersion performance and porosity of the block are better. This is the result of the increase in porosity after the block is gradually formed and the large fluidity before forming, which makes it easier to counteract the dispersion. Compared with unfrozen concrete, freezing will slightly enhance the anti-dispersion performance of the block, increase the porosity water absorption rate, but the error of the bonding strength is within 0.2%. This is because the freezing of the outer layer keeps the internal fresh concrete as a whole, reducing the dispersion effect of the fresh concrete when it is put into water in the early stage. However, the melting of the ice that partially fills the pores will also increase the porosity water absorption rate.

[0077] Second, the material properties of the materials prepared in Examples 2-3 and Comparative Examples 2-3 were tested. The specific test method was carried out according to the method in (4) of the above test plan. The specific results are shown in Figure 4 - 5 ; Figure 4 is a statistical chart of the mass loss rate of different blocks after falling into the water surface; Figure 5 is a statistical chart of the mass loss rate of the falling hammer of different blocks after 1 day;

[0078] Through Figure 4 it can be seen that in Experimental Examples 2-3 using frozen blocks, compared with Comparative Examples 2 and 3, the mass loss rate after falling from the water surface is lower. The non-dispersible concrete and non-dispersible solidified soil after freezing both have good anti-dispersion ability, and the former is better; it can be seen from Experimental Example 3 and Comparative Example 2 that freezing can reduce the mass loss rate after falling from the water surface. And it can be seen from Comparative Examples 2 and 3 that the solidified soil with an anti-dispersion agent has a lower mass loss rate after falling from the water surface than the non-solidified soil. Therefore, the anti-dispersion agent and freezing can effectively reduce the mass loss rate after falling from the water surface;

[0079] The results of the falling hammer experiment are as shown in Figure 5 , the ordinary solidified soil material is relatively loose and has more mass loss. The mass loss rate of Comparative Example 2 decreases after adding an anti-dispersion agent. The error of the mass loss rate between Experimental Examples 2-3 and Comparative Example 2 is within 0.2%. Among them, the mass loss rate of the non-dispersible frozen block before the initial setting in Experimental Example 2 is lower than that of the non-dispersible frozen solidified soil block in Experimental Example 3, but both have good anti-dispersion ability and bonding stability. Therefore, the anti-dispersion frozen block of the present invention has good effects in terms of anti-dispersion performance and bonding stability.

[0080] Third, the performance of the material prepared in Example 4 was tested. The specific test method: Put the frozen block into the mold, demold it after thawing for 1 hour, measure its weight and put it into water. After 1 day, take it out of the water, demold it and conduct a repeated falling hammer experiment. Use a 1 kg falling hammer to continuously fall from a height of 50 cm to test the mass loss rate of the block to characterize the bonding stability of the material. The specific results are shown in Figure 6 ; Figure 6 is a statistical chart of the mass loss rate of the falling hammer of different forms of concrete frozen blocks;

[0081] Testing revealed that all three specimen types exhibited good adhesion, with the solid-fixed specimen exhibiting greater bond stability, making it suitable for use as an anti-scour structure after initial set in the upper layer. While the integrity of the gravel-like specimen was inferior to that of the cube-like specimen, the drop weight loss was similar, resulting in better adaptability to the riverbed. The irregular shape more easily fractured the outer frozen layer, releasing pre-initial set bonding material to build bond strength.

[0082] 4. The project is located in Haikou City, Hainan Province, which is a serious scouring area with abundant rainfall and large water flow, which can easily cause scouring damage to underwater structures such as bridge piers. The technical solutions recorded in Experimental Examples 5 to 7 and Comparative Example 4 are applied to the simulation experiment of this project. A fixed bridge pier with a height of 100 cm and a diameter of 30 cm is placed in a 1 cubic meter transparent glass box. The bottom is a semi-ellipsoidal pit with a depth of 10 cm, a center length of 80 cm and a width of 40 cm. Sea sand is used to fill the bottom of the pit. The water flow depth is 50 cm. The glass box is provided with a water inlet and a water outlet. The water inlet is connected to a high-pressure water gun. A test weight scale is placed under the glass box. The effects of the technical solutions recorded in Examples 5 to 7 and Comparative Example 4 are analyzed by dynamic observation method.

[0083] During the test, the mass loss in a static water thawing environment was first tested. The mass loss of the frozen block after thawing at different flow rates for 12 hours was tested using a high-pressure water gun and compared with ordinary concrete with the same proportion to test the anti-scour performance of different technical solutions and the overall stability of the frozen block. The bond strength was tested in accordance with the test procedures for hydraulic concrete: 150mm×75mm×150mm test blocks of the upper and lower layers of each experimental example were placed in a 300mm cubic mold. After soaking in water for 1 day, the splitting tensile strength was demolded and tested as the bond strength. The specific results are shown in Table 2.

[0084] Table 2:

[0085] Group Static water mass loss rate % Dynamic water mass loss rate % Bond strength (Mpa) Experimental Example 5 0.84 2.5 2.32 Experimental Example 6 0.87 3.4 2.45 Experimental Example 7 0.86 3.1 2.24 Comparative Example 4 0.92 3.8 2.43 Ordinary concrete 2.8 8.9 1.8

[0086] As shown in Table 2, it can be seen from the bonding strength that the bonding strength of the frozen blocks before initial setting is the highest in both Comparative Example 4 and Experimental Example 6, and the bonding strength of the frozen blocks after initial setting is the lowest in both Experimental Example 7, while the bonding strength between the frozen blocks before and after initial setting in Experimental Example 5 and Experimental Example 6 is intermediate. This is because the bonding ability of the inner layer of the frozen block before initial setting is stronger than that of the frozen block after initial setting after the outer frozen layer breaks and melts.

[0087] The lower layers of Comparative Example 4 and Experimental Examples 5-6 all used frozen blocks before initial setting, which had good adaptability to the bottom of the scouring pit, such as Figure 7As shown, combining the test results, it can be seen that in Experimental Examples 5 to 7, upper and lower double-layer protection measures are adopted. In Experimental Example 6, the upper structure before initial setting is used, which is more likely to be washed away under high-speed water flow compared to Experimental Example 5. In Experimental Example 7, the upper and lower layer structures after unified initial setting have a higher mass loss than Experimental Example 5 under high-flow velocity tests during long-term scouring. This is because the lower layer of Experimental Example 5 is denser, has stronger resistance to penetration, and has better bonding performance with the upper layer. Therefore, the mass loss is lower.

[0088] In Experimental Example 5, upper and lower layer frozen blocks are adopted, and in Comparative Example 4, a single-layer protection measure is adopted. Both methods have good protection effects on underwater concrete structures, making the influence of water flow scouring not obvious. However, in comparison, the relatively loose structure in Comparative Example 4 will experience a loss phenomenon under the action of water flow. In Experimental Example 5, a layer of post-initial-setting frozen embedded blocks is added to the pre-initial-setting frozen blocks, providing a stable hydrostatic hydration environment for the lower layer of frozen blocks and also reducing the pores in the lower layer of frozen blocks after thawing under the action of gravity. Compared with Comparative Example 4, the anti-scouring performance of Example 5 is improved, and the overall stability of the blocks is stronger.

[0089] In summary, by comparing with the underwater operation of ordinary concrete, it can be seen that the technical solution of this application can effectively increase the anti-scouring ability of underwater concrete structures. Especially under the premise that erosion problems have occurred in underwater concrete structures and pits have appeared in the riverbed, it can also effectively improve the durability of underwater concrete structures.

[0090] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A preparation method of an erosion-resistant layer based on a frozen mass, characterized in that, Put the cohesive material blocks frozen before initial setting to level the pits on the underwater riverbed, and then put the cohesive material blocks frozen after initial setting on the cohesive material blocks frozen before initial setting as the stable reinforcement layer; The raw materials of the cohesive material include cement, sand, gravel, water reducer, flocculant and water; or the raw materials of the cohesive material include red clay, organic soil solidifying agent, water reducer and flocculant; The preparation method of the cohesive material block frozen before initial setting is: place the cohesive material in a frozen environment for freezing treatment before initial setting, so that the cohesive material forms a block with the outside frozen into a solid state and the inside in a liquid state, that is, the cohesive material block frozen before initial setting is obtained; The preparation method of the cohesive material block frozen after initial setting is: place the cohesive material in a frozen environment for freezing treatment after initial setting, so that the cohesive material forms a block frozen as a whole, that is, the cohesive material block frozen after initial setting is obtained.

2. The preparation method of the erosion-resistant layer based on a frozen mass according to claim 1, characterized in that, The volume of the cohesive material block frozen after initial setting is larger than that of the cohesive material block frozen before initial setting.

3. The preparation method of the anti-scouring layer based on frozen blocks according to claim 1 or 2, characterized in that, The preparation raw materials of the cohesive material block frozen before initial setting and the cohesive material block frozen after initial setting are the same.

4. The preparation method of the erosion-resistant layer based on frozen blocks according to claim 1, characterized in that, The mass ratio of the cement: sand: gravel: water = 400 - 450: 150 - 200: 1000 - 1500, and the water reducer and the flocculant respectively account for 0.5 - 5% of the weight of the cement.

5. The preparation method of the erosion-resistant layer based on the frozen mass according to claim 4, characterized in that, Among the gravel, the gravel with a size of 5 - 10 mm accounts for 30 - 50% of the total amount of gravel, and the gravel with a size of 10 - 20 mm accounts for 50 - 70% of the total amount of gravel.

6. The preparation method of the erosion-resistant layer based on a frozen mass according to claim 1, characterized in that, The mass ratio of the red clay to the organic soil solidifying agent is 2 - 4: 1, and the water reducer and the flocculant respectively account for 0.5 - 5% of the total weight of the organic soil solidifying agent.

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