One-step forming construction method for lining concrete and surface wear-resistant layer of hydraulic vertical wall hole

Abstract

The application discloses a one-time forming construction method for lining concrete and surface wear-resistant layer of a hydraulic vertical wall hole, which separates the low-strength ordinary concrete of the inner base layer (or base body layer) of the tunnel and the high-strength impact-resistant wear-resistant layer of the surface layer by using a partition plate or a partition net and simultaneously pours the two layers by using a pumping mode, so that the temperature control and crack prevention problem in the conventional case can be avoided, the temperature control and crack prevention problem in the pumping concrete into the bin method is solved, the wear-resistant layer material consumption is reduced, the strength and wear-resistant performance of the wear-resistant layer are improved, the thickness of the outer wear-resistant layer is reduced, so that the problem that the compressive strength of the outer wear-resistant layer is too high and the temperature control and crack prevention difficulty is too large to cause cracks does not need to be considered, and a higher compressive strength, for example, C60, C80, even C100 or higher, can be used for the outer layer (the specification requires that the compressive strength of the organic material is not less than C60-C80).

Description

Technical Field

[0001] This invention relates to the field of hydraulic engineering construction, and in particular to a method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic vertical wall openings. Background Technology

[0002] According to the design requirements of the "Technical Specification for Anti-Abrasion and Anti-Cavitation Concrete of Hydraulic Structures" DL / T5207-2021, "the part of the vertical wall below the water surface line of the high-speed sand-containing water flow hydraulic tunnel should be designed as anti-abrasion concrete, with a thickness of not less than 300mm and a thickness of not less than 100mm for the reinforcement protective layer. The anti-abrasion surface concrete and the base ordinary concrete should be reliably bonded, and the design strength of the base concrete should be reasonably selected." The traditional tunnel facade structure tunnel lining concrete is generally designed with a low compressive strength. C25 tunnel lining concrete is used inside. During construction, wire mesh is used as a separation interface. However, the position of the wire mesh cannot be fixed and cannot withstand the horizontal pressure caused by the difference in concrete height due to the asynchronous construction of the two sides. Moreover, the two types of concrete are required to be pumped into the formwork at the same time during construction, which makes the construction difficult. In addition, the space inside the pouring chamber is small and there are oblique fixed reinforcement bars blocking the way. The installation of the partition is difficult. After adding wire mesh as a separation interface, it is impossible for people to enter the chamber for vibration operation.

[0003] In recent years, some large-scale tunnel projects have adopted the normal concrete placement method throughout the entire thickness of the vertical wall to reduce the risk of temperature cracks caused by excessive cement usage during pumped concrete pouring for the vertical wall. This method has achieved good crack prevention results. However, the normal concrete placement method is difficult to implement and slow. After placement, the concrete has poor fluidity and reduced filling performance. It is also hindered by the dense surface reinforcement, making it difficult to release air bubbles. As a result, there are many air bubbles on the surface of the poured concrete. In addition, this method requires manual vibration, but the working space is limited, making vibration difficult. Moreover, when facing densely reinforced concrete that cannot penetrate the surface reinforcement layer, the normal concrete placement method cannot be used to solve the problem of temperature control and crack prevention. Furthermore, the normal concrete pouring method can only be used for pouring within a certain height range. Pumped pouring is required for the upper part of the arch, which increases the construction process, increases construction costs, and reduces construction efficiency. For small tunnels, the construction environment is small, and the space inside the placement chamber is too small for personnel to enter. Therefore, this normal concrete placement method is no longer suitable for tunnel construction. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a one-time molding construction method for ordinary concrete lining and surface wear-resistant material in hydraulic engineering vertical wall openings. By using partitions or meshes to separate the layers, it is possible to simultaneously pump the low-strength ordinary concrete base layer and the high-strength impact-resistant and wear-resistant surface layer. This method solves the problem of temperature control and crack prevention, while also improving work efficiency, reducing costs, decreasing the amount of wear-resistant material used, and increasing the strength of the wear-resistant layer. Wear-resistant materials can be flexibly selected according to the project requirements.

[0005] The technical solution of this invention is:

[0006] The construction method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings includes the following steps:

[0007] S1. Tie the steel mesh on the surface to be constructed, place the partition parallel to the outside of the outer steel mesh and connect it to the steel mesh in a movable manner, connect the lifting equipment to the top of the partition, and lay the grouting pipe of the grouting equipment along the top of the steel mesh.

[0008] S2. Position the steel formwork trolley and install the end caps on both ends of the trolley formwork.

[0009] S3. Prepare wear-resistant slurry, mix and inject it into the space between the partition and the steel mold trolley;

[0010] S4. Simultaneously pour the internal ordinary concrete and the external impact-resistant and wear-resistant layer concrete. Pump the ordinary concrete of the tunnel lining matrix in the space between the partition and the bedrock. Use a vibrator to insert into the matrix concrete to vibrate and compact it. The surface impact-resistant and wear-resistant layer concrete is poured using a self-compacting pouring method.

[0011] S5. Repeat steps S3 and S4 until the designed wear-resistant layer pouring height is reached. Lift the partition from the top and use a pump to pour ordinary concrete to the top.

[0012] S7. After reaching the demolding strength, remove the formwork, move the steel formwork trolley to the next construction site, and repeat the above steps until the construction is completed.

[0013] In step S1, the partition is connected by a magnet, and the lifting device is a manual hoist.

[0014] In step S1, the partition can also be replaced with a non-removable steel wire mesh. The non-removable steel wire mesh is fixed on the surface or inside of the outer steel mesh. In step S3, when the non-removable steel wire mesh is installed inside the outer steel mesh, the inner concrete is poured first and then the wear-resistant slurry is poured.

[0015] In step S4, the composition of the wear-resistant slurry components is as follows:

[0016] 1 part cement, 0.05-0.2 parts fly ash, 0-0.15 parts silica fume, 0.28-0.32 parts water, 1-3.05 parts sand, 0.0025-0.006 parts polycarboxylate powder water-reducing agent, retarder, and hydration heat inhibitor.

[0017] The cement is ordinary Portland cement, Portland cement, low-heat or medium-heat Portland cement, with a strength grade of 42.5, 52.5 or 62.5.

[0018] The fly ash is Grade I fly ash or cenosphere fly ash.

[0019] The components may further include an expanding agent and an early strength agent, wherein the expanding agent is 0.05-0.08 parts.

[0020] The partition is made of aluminum plate, steel plate or plastic resin plate, and the top of the partition is bent outward at 45 degrees.

[0021] The partition plate is 1000mm high. When the vertical section of the partition plate is poured to a height of less than or equal to 100mm, the partition plate is lifted by a lifting device until it is embedded in the concrete slurry to a depth of 100mm.

[0022] The beneficial effects of this invention are:

[0023] By installing partitions, the layered concrete structure is erected on top of the reinforced concrete layer, allowing construction to proceed within the confined space of the tunnel. This results in a shorter construction period, better compressive strength, impact resistance, and abrasion resistance of the concrete. The inner concrete layer has a more rational mix proportion and lower grade, leading to less heat release and addressing issues of thermal expansion and contraction. The one-time molding process allows the abrasion-resistant layer and the inner concrete structure to develop strength simultaneously, resulting in good bonding and improved overall structural integrity, achieving the required compressive strength. The high proportion of cementitious materials in the abrasion-resistant layer and the low proportion of structural adhesive in the inner concrete layer reduce costs and save materials, thus lowering the demand for abrasion-resistant aggregates. This method reduces the cost of transporting and cooling wear-resistant aggregates, ensuring uniform dispersion of aggregates in the wear-resistant layer to achieve the desired impact and wear resistance. After construction using this method, the surface after water exposure is smooth with controllable unevenness. Construction is simple and has good bonding. The thickness of the impact and wear-resistant layer or more wear-resistant materials can be appropriately increased according to the actual project conditions. The uniformity of the wear-resistant layer is greatly improved, and the surface after mud and sand abrasion is smoother and flatter than the surface after abrasion of higher grade concrete. Compared with the conventional one-time placement method of impact and wear-resistant concrete, this method saves processes, reduces costs, has a wide range of applications, and the surface strength is higher than that of conventional concrete. Detailed Implementation

[0024] The embodiments of the present invention will be further described below. Example

[0025] The specific steps for the one-time molding construction method of concrete lining and surface wear-resistant layer for hydraulic wall openings are as follows:

[0026] 1. Tie the reinforcing mesh according to the design requirements. Place the partition plate parallel to the outer layer of the reinforcing mesh, and use four magnets to attach the partition plate to the mesh. Hang the hoist and attach it to the partition plate. Connect the grouting pipe to the grouting nozzle. Lay the grouting pipe along the reinforcing mesh to the top or inlet, leaving sufficient length. Once the formwork trolley is in place, connect the grouting pipe to the ground-based grouting pump. Connect the grouting pump to the wear-resistant grout mixer.

[0027] When using a mesh or a mesh that does not require removal of formwork, after the reinforcing bars are tied, fix the mesh or formwork that does not require removal to the surface or inside of the reinforcing bar mesh.

[0028] 2. Position the steel formwork trolley and install the end cap templates at both ends of the trolley template. Press the partition plates tightly against the end cap templates and fix the partition plates in place. The ends of the remaining adjacent partition plates should overlap by 100mm. Ensure that the ends of the partition plates overlap and that the total length is equal to the length of the steel formwork trolley template. Install ultrasonic level gauges on both sides of the unobstructed area of ​​the pouring location to monitor the pouring liquid level in real time.

[0029] 3. Pour the wear-resistant mixed slurry into the mixer, add water according to the ratio and mix. Use a grouting pump (grouting pump) to inject grout into the space between the partition (or partition net or partition) and the steel mold trolley. The grouting height reaches 300mm. The value is fed back through the level gauge. At the same time, pour the internal concrete and the external impact-resistant and wear-resistant layer concrete. Control the pumping rate to keep the level difference between the inside and outside within 100mm.

[0030] 4. Using a concrete pump, ordinary concrete of 280mm height is pumped into the space between the partition and the bedrock through the feed window or top. The concrete is compacted by inserting a vibrator into the concrete. The surface impact and wear-resistant concrete mortar is poured using a self-compacting method, so that it can achieve good density and smoothness without separate vibration.

[0031] 5. If the partition height is 1000mm, repeat steps ③ and ④, each layer being 250mm to 300mm. When the vertical section of the partition is less than or equal to 100mm, use a hand-operated hoist to lift the partition upwards until the partition is embedded in the concrete slurry to a depth of about 100mm, then fix the partition.

[0032] 6. Repeat steps 3 and 4. When the required pouring height (generally one meter above the waterline) is reached, lift the partition from the top and use a pump to pour ordinary concrete to the top.

[0033] 7. Repeat steps 3-6 to complete the construction.

[0034] Each time, after filling the base with wear-resistant grout and then pouring ordinary concrete, use vibrating rods and other equipment to properly vibrate the double-layer structure to ensure full bonding.

[0035] After the overall pouring is completed, the partition is lifted out from the top.

[0036] When using a mesh screen or a formwork that does not need to be removed, there is no need to remove the mesh screen or the formwork.

[0037] The portion above the waterline generally does not require a wear-resistant layer; this part can be poured with low-grade base concrete of full thickness. After pouring to the top, remove the steel formwork trolley when it is ready to be demolded, move the steel formwork trolley to the next construction section, and repeat the above process for pouring. The previous section is then properly moisturized and cured.

[0038] A partition is used to separate the ordinary concrete base and the impact-resistant and wear-resistant material, allowing the wear-resistant surface layer to be poured simultaneously with the base concrete in a single pour. The partition is positioned outside the outer layer of reinforcing steel bars in the wall, or a formwork or wire mesh is placed close to the reinforcing mesh. The reinforcing mesh bears the lateral pressure on the partition generated by the initial pouring of the outer wear-resistant layer material to a certain height (generally 300-50mm thick, consistent with the vertical layer thickness of the inner ordinary concrete pour), ensuring the partition does not deform and its position is secure. Then, the ordinary concrete base layer on the other side of the partition is pumped and poured to a height slightly lower than the wear-resistant layer by 50-100mm. After pouring on both sides, the inner base concrete is vibrated until compacted, using a self-leveling and self-compacting mix for the wear-resistant material. After 2-3 layers have been poured to a height of 1000mm, a manual hoist is used to lift the partition to pour the next layer. When lifting the partition, do not lift it completely above the level of the lower pouring layer. A certain height of the partition should be retained within the lower pouring layer, approximately 100mm deep. The specific retention depth in actual construction should be determined based on the specific gravity difference and consistency resistance of the inner and outer layers. This ensures that when the upper wear-resistant material is poured to the set height, the outer wear-resistant layer material will not be pressed into the inner ordinary concrete layer. Alternatively, the lower edge can be retained at a depth of 100mm, controlling the pouring speed of the outer wear-resistant material to be roughly the same as the rising speed of the inner base concrete, slightly higher (100-200mm), to ensure that the grout on both sides of the partition does not cross-contaminate.

[0039] Every 1000mm increase in pouring height (the specific interval height can also be summarized from practical experience), a wear-resistant layer with a thickness of about 200mm can be poured within the open area. When pouring this layer, the grouting pipe on the partition can be removed to directly pour the wear-resistant slurry. This can ensure that when the steel formwork trolley is removed in the early stage, the internal concrete strength is too low and the wear-resistant layer is not strong enough and falls off.

[0040] The surface wear-resistant layer material poured according to this construction method is approximately 100mm thick, which is basically consistent with the thickness of the reinforcing steel protective layer in most cases. This does not meet the specification requirement that the wear-resistant layer thickness should not be less than 300mm. However, considering that if the wear-resistant layer has already reached the surface reinforcing steel layer under wear, the wear is already very severe. Further wear will inevitably reach the load-bearing reinforcing steel layer, threatening the tunnel structure. In this case, the wear-resistant layer will definitely need to be repaired in the project. Therefore, although the wear-resistant layer of this method does not meet the specification requirement of more than 300mm, a thickness of 100mm is actually sufficient for the use of the wear-resistant layer.

[0041] No-removal partition: steel wire mesh, with a maximum gap of less than approximately 5mm.

[0042] The partition can be made of aluminum plate, steel plate, plastic resin board, or other materials that meet construction requirements and have a thickness not exceeding 3mm. The top 100mm is folded outward at a 45° angle, extending approximately 10mm into the inner surface of the steel formwork trolley, where a 10mm rubber strip contacts the inner surface of the formwork. The other end of the top is fitted with nylon Velcro every 500mm for securing to the reinforcing bars. The vertical surface of the partition is parallel to and tightly attached to the reinforcing mesh, with a total length roughly equal to the length of the construction silo. It can also be segmented appropriately, with each segment divided into sections every 2.5-3 meters along its total length. Each section has 100mm rubber strips at both ends, allowing the partition to overlap with the steel formwork trolley end caps and with each section. This partition forms a vertical barrier separating the tunnel lining concrete from the surface wear-resistant material. During construction, the space between the partition and the steel formwork trolley is first filled with wear-resistant material, followed by the pouring of ordinary low-strength concrete for the tunnel lining inside the partition. The pouring height reaches 50mm below the fold line of the partition plate. After vibrating the materials on both sides until compacted, the partition plate is lifted 300mm using a lifting device to the next layer for pouring. The upper layer of the two materials is then poured in the same manner. The length of the partition plate is the same as that of the pouring chamber, or it can be divided into several sections for ease of installation. The joints between sections overlap by 30-50mm. The partition plate has a folded cross-section and a hinged baffle with a limiter at the top. The baffle folds down to a maximum angle of 45° towards the steel formwork trolley, leaving a 10-20mm gap between it and the steel formwork trolley to prevent concrete from falling into the wear-resistant material during pouring and to facilitate removal. A 150mm long section is retained above the fold line, and a 1000-1500mm long vertical section is retained. Wear-resistant material injection pipe and injection method: According to the pouring progress, a grouting pump with a flow rate of 0.01m3 / s is selected as the conveying equipment for wear-resistant grout. It is connected to the grouting pipe nozzle located in the middle of the inclined section of the partition through a plastic high-pressure hose with a diameter of 50-100mm.

[0043] Wear-resistant slurry mixing weight ratio:

[0044] Cement, fly ash, silica fume, water, sand, polycarboxylate superplasticizer, retarder, heat of hydration inhibitor.

[0045] Cement: Ordinary Portland cement, Portland cement, low-heat or medium-heat Portland cement, strength grade 42.5, 52.5 or 62.5 MPa, 1 part;

[0046] Fly ash: Grade I fly ash, filament fly ash, 0.05-0.2 parts;

[0047] Silica fume (silica powder): SiO2 content meets the specifications, 0.03-0.15 parts;

[0048] Water: 0.28-0.4 parts;

[0049] Polycarboxylate superplasticizer or high-efficiency superplasticizer (powder): 0.0025-0.006 parts;

[0050] Sand (quartz sand): The mud content meets the specifications, 1-3 parts;

[0051] The sand can also be one or more of the following: well-graded brown corundum, corundum, quartz sand, cast stone sand, basalt sand, or natural sand with high hardness or high quartz content, mixed in a certain proportion. The amount of sand mixed with the quartz sand is calculated by weight of each sand in the same volume.

[0052] Expanding agent (lightly calcined magnesium oxide, calcium oxide, or sulfoaluminate): 0.05-0.08% of early strength agent as needed.

[0053] Whether to add the expansion agent and the early strength agent in the above materials and the dosage should be determined according to the engineering requirements.

[0054] The mortar spread should be 160-200mm. If reducing the spread allows for proper placement in the mortar container, a smaller spread can be used.

[0055] The above materials are pre-mixed evenly according to the proportion, bagged, and transported to the construction site. Water is added according to the proportion, and the mixture is stirred evenly using a forced mixer and poured using a small grouting pump.

[0056] This construction method avoids the temperature control and crack prevention problems encountered in conventional methods, solves the temperature control and crack prevention problems in the pumped concrete placement method, reduces the amount of wear-resistant layer material used, improves the strength and wear resistance of the wear-resistant layer, and eliminates the need to consider that the compressive strength of the outer wear-resistant layer is too high, which would lead to excessive difficulty in temperature crack prevention and cracking. The outer layer can use a higher compressive strength, such as C60, C80, or even C100 or higher (the specification requires the compressive strength of organic materials to be no less than C60-C80).

[0057] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings, characterized in that, Includes the following steps: S1. Tie the steel mesh on the surface to be constructed, place the partition parallel to the outside of the outer steel mesh and connect it to the steel mesh in a movable manner, connect the lifting equipment to the top of the partition, and lay the grouting pipe of the grouting equipment along the top of the steel mesh. S2. Position the steel formwork trolley and install the end caps on both ends of the trolley formwork. S3. Prepare wear-resistant slurry, mix and inject it into the space between the partition and the steel mold trolley; S4. Simultaneously pour the internal ordinary concrete and the external impact-resistant and wear-resistant layer concrete. Pump the ordinary concrete of the tunnel lining matrix in the space between the partition and the bedrock. Use a vibrator to insert into the matrix concrete to vibrate and compact it. The surface impact-resistant and wear-resistant layer concrete is poured using a self-compacting pouring method. S5. Repeat steps S3 and S4 until the designed wear-resistant layer pouring height is reached. Lift the partition from the top and use a pump to pour ordinary concrete to the top. S7. After reaching the demolding strength, remove the formwork, move the steel formwork trolley to the next construction site, and repeat the above steps until the construction is completed.

2. The method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings according to claim 1, characterized in that, In step S1, the partition is connected by a magnet, and the lifting device is a manual hoist.

3. The method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings according to claim 1, characterized in that, In step S1, the partition can also be replaced with a non-removable steel wire mesh. The non-removable steel wire mesh is fixed on the surface or inside of the outer steel mesh. In step S3, when the non-removable steel wire mesh is installed inside the outer steel mesh, the inner concrete is poured first and then the wear-resistant slurry is poured.

4. The method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings according to claim 1, characterized in that, In step S4, the composition of the wear-resistant slurry components is as follows: 1 part cement, 0.05-0.2 parts fly ash, 0-0.15 parts silica fume, 0.28-0.32 parts water, 1-3.05 parts sand, 0.0025-0.006 parts polycarboxylate powder water-reducing agent, retarder, and hydration heat inhibitor.

5. The method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings according to claim 4, characterized in that, The components may also include an expanding agent and an early strength agent, wherein the expanding agent is 0.05-0.08 parts.

6. The method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings according to claim 1, characterized in that, The partition is made of aluminum plate, steel plate or plastic resin plate, and the top of the partition is bent outward at 45 degrees.

7. The method for one-time molding of concrete lining and surface wear-resistant layer for hydraulic wall openings according to claim 1, characterized in that, The partition plate is 1000mm high. When the vertical section of the partition plate is poured to a height of less than or equal to 100mm, the partition plate is lifted by a lifting device until it is embedded in the concrete slurry to a depth of 100mm.