Water tank simulation test device and method for underwater rock-fill concrete

Abstract

The invention relates to the technical field of concrete, and discloses a water tank simulation test device and method for underwater rock-fill concrete, and the device comprises a mobile vehicle, a water tank system, an underwater rock-fill mold, a pouring system, and a hoisting system. The water tank simulation test device provided by the invention can simulate the pouring of underwater self-compacting concrete mixtures with different flow rates, different water depths, different rockfill void ratios and different performances, and then the underwater rockfill void ratio, the volume weight of an underwater rockfill concrete body, the pouring compaction degree, the concrete strength and the anti-freezing grade are obtained through tests; the test device is easy to operate and accurate in result, further provides data support for underwater rock-fill concrete engineering design, and provides a detection and evaluation method for construction quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and specifically relates to a flume simulation test device and method for underwater rockfill concrete. Background Technique

[0002] The construction technology of rockfill concrete is a brand-new large-volume concrete construction technology. It utilizes the high fluidity, anti-separation performance, and self-flow characteristics of self-compacting concrete to randomly fill self-compacting concrete within larger-sized rubble to form a concrete rockfill body. It has the advantages of less cement consumption, small hydration temperature rise, low comprehensive cost, fast construction speed, good volume stability, and strong interlayer shear resistance, and is currently widely used. Applying rockfill concrete to underwater projects, especially for emergency repairs and underwater construction during the high-water period, is of great significance. However, due to the relatively high requirement for anti-dispersion of underwater concrete and the limited cement loss, that is to say, underwater rockfill concrete should not only meet the high fluidity, anti-separation, and self-flow of rockfill concrete, but also meet the anti-dispersion of underwater non-dispersible concrete, so that the final concrete performance, strength, and durability meet the requirements. Before the construction of underwater rockfill concrete, the construction unit cannot know the engineering effect after construction, and different construction processes and environments will directly affect the final engineering quality. For example, different porosities of the rockfill, different slump flow values of the concrete mixture, different water depths, and different water flow velocities all directly affect the performance of underwater rockfill concrete, including the unit weight and compactness of the rockfill concrete after pouring, as well as the strength and frost resistance of the rockfill concrete. These cannot reflect the true overall engineering quality of underwater rockfill concrete through sampling.

[0003] To solve the above problems, the present invention proposes a flume simulation test device to simulate different working conditions, pour underwater rockfill concrete in the flume, and after pouring, evaluate the unit weight of the underwater rockfill concrete and the compactness of the rockfill void filling, and conduct compressive and frost resistance tests on the concrete rockfill body to evaluate the durability of the underwater rockfill concrete.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] To solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0006] A flume simulation test device for underwater rockfill concrete, comprising:

[0007] Comprising a mobile vehicle, a flume system, an underwater rockfill mold, a pouring system, and a hoisting system.

[0008] Flume system: Comprising a flume 14, which is arranged on the mobile vehicle;

[0009] Underwater rockfill mold: It is a wooden mold groove 13, which is arranged inside the water tank 14, and the depth of the water tank 14 is greater than the depth of the mold.

[0010] Pouring system: It is a small concrete delivery pump 10, which is arranged on the mobile vehicle.

[0011] Lifting system: It is an electric hoist 7, which is suspended on the mobile vehicle and is used for lifting the finished cast concrete test block.

[0012] As a preferred embodiment of the present invention, the mobile vehicle includes a base plate 1, vertical frames 4 are installed at both ends on the upper surface of the base plate 1, and a cross beam 6 is horizontally installed above the two vertical frames 4.

[0013] As a preferred embodiment of the present invention, the water tank 14 is arranged on the middle bracket welded to the base plate 1; the wooden mold groove 13 is arranged in the inner cavity of the water tank 14; and the wooden mold groove 13 is filled with rockfill.

[0014] As a preferred embodiment of the present invention, a reflux temporary storage tank 2 is arranged on the base plate 1 on the left side of the water tank 14; a side bracket is arranged on the base plate 1 on the right side of the water tank 14, and a temporary storage water tank 8 is arranged on the side bracket.

[0015] As a preferred embodiment of the present invention, drain pipes are connected to the left sides of both the water tank 14 and the temporary storage water tank 8, and solenoid valves 15 are installed on the drain pipes. Flow velocity sensors 16 are installed in the water tank 14 and the temporary storage water tank 8 at the inlet port positions of each drain pipe.

[0016] As a preferred embodiment of the present invention, a rotating shaft 5 is installed on the cross beam 6, a rotating lifting arm 3 is fixed at the lower end of the rotating shaft 5, an electric hoist 7 is installed at one end of the rotating lifting arm 3 away from the rotating shaft 5, and the electric hoist 7 is located directly above the wooden mold groove 13.

[0017] As a preferred embodiment of the present invention, the small concrete delivery pump 10 is arranged on the base plate 1 where the temporary storage water tank 8 is located.

[0018] As a preferred embodiment of the present invention, a circulating water pump 12 is arranged on the base plate 1 below the water tank 14. The inlet pipe of the circulating water pump 12 is connected to the reflux temporary storage tank 2, and the drain pipe of the circulating water pump 12 is connected to the temporary storage water tank 8.

[0019] As a preferred embodiment of the present invention, the present invention also discloses a method for simulating a water tank test of underwater rockfill concrete, including the following steps:

[0020] Step S1: Close the drain pipe at the end of the water tank 14, fill the water tank 14 with water until it is close to the top of the water tank 14;

[0021] Step S2: Place the prepared wooden formwork groove 13 into the water tank 14 according to the form of the actual engineering rockfill concrete. The wooden formwork groove 13 is located on the geotextile fabric.

[0022] Step S3: Fill the wooden formwork groove 13 with rockfill. Weigh the total mass m_rockfill of the rockfill, and then start placing the rockfill into the wooden formwork groove 13. The particle size of the rockfill is larger at the bottom and smaller at the top, with a combination of sizes to reduce the voids in the rockfill.

[0023] Step S4: Mix the concrete. For the mixing of underwater self-compacting concrete, it is necessary to maintain the anti-dispersibility of the cement and ensure the slump flow value of the mixture. To ensure sufficient perfusion of the underwater rockfill, the slump flow value should not be less than 550 mm.

[0024] Step S5: Control the construction parameters. Select the construction parameters to be tested before perfusion; the slump flow can be selected as 550 mm, 600 mm, 650 mm, 700 mm, and the void ratio can be selected as 50 - 60%. Select different slump flows to test the perfusion effect of the concrete mixture and the cement loss.

[0025] Step S6: Underwater perfusion. Transport the concrete mixture to the funnel through the small concrete pump 10. Connect the outlet of the funnel to the chute pipe. Open the discharge valve to allow the mixture to flow into the rockfill body in the underwater wooden formwork groove 13 until the wooden formwork groove 13 is filled, and make the mixture perfusion form a small mountain shape above the top surface of the wooden formwork groove 13.

[0026] Step S7: Static curing. After 3 - 7 days of static curing, open the water discharge valve of the water tank 14 to empty the water.

[0027] Step S8: Lift out of the groove by hoisting with the electric hoist 7 in cooperation with the cross beam 6. Lift the poured rockfill concrete body out of the groove. After removing the formwork, cover it with geotextile fabric and cure it naturally for 28 days, and measure its total volume V_total.

[0028] Step S9: Conduct strength testing and frost resistance testing of the underwater rockfill concrete.

[0029] The present invention has the following beneficial effects compared with the prior art:

[0030] The water tank simulation test device provided by the present invention can simulate water flows with different velocities, different water depths, different rockfill porosity, and different performances of underwater self-compacting concrete mixtures. After perfusion, the underwater rockfill porosity, the unit weight of the underwater rockfill concrete body, the pouring compactness, the concrete strength, and the frost resistance grade can be obtained through tests. The test device is easy to operate and the results are accurate. Furthermore, it provides data support for the design of underwater rockfill concrete projects and a detection and evaluation method for construction quality.

[0031] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0032] In the accompanying drawings:

[0033] Figure 1 It is a schematic structural diagram of a flume simulation test device for underwater rockfill concrete.

[0034] In the figure: 1. Substrate; 2. Return water storage tank; 3. Rotary jib; 4. Vertical frame; 5. Rotary shaft; 6. Cross beam; 7. Electric hoist; 8. Temporary water storage tank; 9. Return pipe; 10. Small concrete pump; 11. Rockfill; 12. Circulating water pump; 13. Wooden formwork groove; 14. Flume; 15. Solenoid valve; 16. Flow velocity sensor. Specific embodiments

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention.

[0036] As Figure 1 shown, a flume simulation test device for underwater rockfill concrete includes:

[0037] It includes a mobile vehicle, a flume system, an underwater rockfill mold, a pouring system, and a hoisting system.

[0038] Flume system: It includes a flume 14, which is arranged on the mobile vehicle;

[0039] Underwater rockfill mold: It is a wooden formwork groove 13, which is arranged inside the flume 14, and the depth of the flume 14 is greater than the depth of the mold.

[0040] Pouring system: It is a small concrete pump 10, which is arranged on the mobile vehicle.

[0041] Hoisting system: It is an electric hoist 7, which is suspended on the mobile vehicle and is used for hoisting finished concrete test blocks for pouring.

[0042] Furthermore, the mobile vehicle includes a substrate 1, and vertical frames 4 are installed at both ends on the upper surface of the substrate 1, and a cross beam 6 is horizontally installed on the upper surface between the two vertical frames 4.

[0043] Furthermore, the flume 14 is arranged on an intermediate bracket welded to the substrate 1; the wooden formwork groove 13 is arranged in the inner cavity of the flume 14; and the wooden formwork groove 13 is filled with rockfill.

[0044] Furthermore, a return water storage tank 2 is arranged on the substrate 1 on the left side of the flume 14; a side bracket is arranged on the substrate 1 on the right side of the flume 14, and a temporary water storage tank 8 is arranged on the side bracket.

[0045] Further, drain pipes are connected to the left sides of the water tank 14 and the temporary storage water tank 8, and solenoid valves 15 are installed on the drain pipes. Flow rate sensors 16 are installed in the water tank 14 and the temporary storage water tank 8 at the positions of the water inlet ports of each drain pipe.

[0046] Further, a rotating shaft 5 is installed on the cross beam 6. A rotating jib 3 is fixed to the lower end of the rotating shaft 5. An electric hoist 7 is installed at one end of the rotating jib 3 away from the rotating shaft 5. The electric hoist 7 is located directly above the wooden formwork groove 13. The small concrete pump 10 is arranged on the base plate 1 where the temporary storage water tank 8 is located. A circulating water pump 12 is arranged on the base plate 1 below the water tank 14. The water inlet pipe of the circulating water pump 12 is connected to the reflux temporary storage tank 2, and the drain pipe of the circulating water pump 12 is connected to the temporary storage water tank 8.

[0047] As a preferred embodiment of the present invention.

[0048] As a preferred embodiment of the present invention.

[0049] The present invention also discloses a method for simulating an underwater rockfill concrete test in a water tank, including the following steps:

[0050] Step S1: Close the drain pipe at the tail end of the water tank 14, and fill the water tank 14 with water until it is close to the top of the water tank 14.

[0051] Step S2: Place the prepared wooden formwork groove 13 into the water tank 14 according to the form of the actual engineering rockfill concrete, and the wooden formwork groove 13 is located on the geotextile.

[0052] Step S3: Stack stones in the wooden formwork groove 13, weigh the total mass m of the stacked stones, and then start placing the stones in the wooden formwork groove 13. The particle size of the stones is larger at the bottom and smaller at the top, and they are arranged in a large-small combination to reduce the voids in the stacked stones.

[0053] Step S4: Mix the concrete. When mixing the underwater self-compacting concrete, it is necessary to maintain the anti-dispersion property of the cement and ensure the slump flow value of the mixture. To ensure sufficient perfusion of the underwater rockfill, the slump flow value should not be less than 550 mm.

[0054] Step S5: Control the construction parameters. Select the construction parameters to be tested before perfusion; the slump flow can be selected as 550 mm, 600 mm, 650 mm, 700 mm, and the void ratio can be selected as 50 - 60%. Select different slump flows to test the perfusion effect and cement loss of the concrete mixture.

[0055] Step S6: Underwater perfusion. Transport the concrete mixture to the funnel through the small concrete pump 10. The outlet of the funnel is connected to a chute pipe. Open the discharge valve to allow the mixture to flow into the rockfill in the underwater wooden formwork groove 13 until the wooden formwork groove 13 is filled, and the mixture is poured above the top surface of the wooden formwork groove 13 to form a small mountain shape.

[0056] Step S7: Static curing. After 3 - 7 days of static curing, open the water discharge valve of the water tank 14 to empty the water.

[0057] Step S8: Lift out of the tank by using the electric hoist 7 in cooperation with the cross beam 6, lift out the cast rockfill concrete body from the tank, cover it with geotextile after form removal, cure it naturally for 28 days, and measure its total volume Vtotal.

[0058] Step S9: Conduct strength detection and frost resistance detection of underwater rockfill concrete.

[0059] Strength detection of underwater rockfill concrete:

[0060] Method 1: Adopt the comprehensive ultrasonic - rebound method. First, conduct rebound testing on the surface of the large test block, then conduct ultrasonic testing on both sides of the large test block. According to the corrected rebound value and sound velocity value, convert its compressive strength according to the Technical Specification for Testing Concrete Compressive Strength by Comprehensive Ultrasonic - Rebound Method T / CECS 02 - 2020.

[0061] Method 2: Drill core samples on the large test block. The diameter of the drill bit is Φ100mm. After grinding both ends flat, conduct compressive tests using a universal testing machine.

[0062] Frost resistance test: Cut the large test block to make frost - resistance standard specimens of 100×100×400mm, and conduct frost resistance tests after curing to the age.

[0063] Calculation method of rockfill void ratio and unit weight of rockfill concrete body:

[0064] The rockfill void ratio P' can be calculated through the total mass of the rockfill weighed before pouring. 堆石 . Weigh the total mass m' of the entire rockfill concrete body. 堆石混凝土 , and the unit weight γ of the rockfill concrete body can be calculated. 堆石混凝土 .

[0065] The rockfill void ratio P' is:

[0066] P' 堆石 =(V 总 - V 堆石 ) / V 总 ×100%

[0067] =(V 总 - m 堆石 / ρ 堆石 ) / V 总 ×100%

[0068] In the formula: P' rockfill is the rockfill void ratio, and the unit is %;

[0069] V 总 is the total volume of the rockfill body, and the unit is m3 ;

[0070] V 堆石 is the volume of the rockfill, with the unit of m 3 ;

[0071] m 堆石 is the total weight of the rockfill, with the unit of t;

[0072] ρ 堆石 is the rockfill density, with the unit of t / m 3 .

[0073] The unit weight γ of the rockfill concrete 堆石混凝土 is:

[0074] γ 堆石混凝土 = m' 堆石混凝土 / V 总

[0075] In the formula: γ 堆石混凝土 is the unit weight of the rockfill concrete, with the unit of t / m 3 ;

[0076] m' 堆石混凝土 is the total mass of the entire rockfill concrete, with the unit of t;

[0077] V 总 is the total volume of the rockfill body, with the unit of m 3 .

[0078] Application Example 1

[0079] Fabricate 5 cubic wooden molds, and use underwater concrete mixtures with different construction parameters to pour the underwater rockfill, and evaluate the influence of concrete mixtures with different working performances on various parameters of the final concrete.

[0080] First, fill the water tank with water, place it, and have slightly more large stones when weighing the stones. According to the volume accounting for 50% of the total volume of the wooden mold, that is, the void ratio is 50%. Then put the stones into the wooden mold. Control the concrete mixture at 550 + 10 mm (subject to actual measurement), control the water depth at 0.45 meters, and control the flow rate at 0.5 m / s (subject to actual measurement). Transport the concrete mixture to the funnel through a small concrete pump. Connect the outlet of the funnel to a chute pipe, open the discharge valve, and let the mixture flow into the rockfill body of the underwater wooden mold until it is filled with the wooden mold, and make the mixture pour above the top surface of the wooden mold to form a small mountain shape. After standing for 3 - 7 days, open the water discharge valve of the water tank to empty the water, hoist the poured rockfill concrete body out of the tank, cover it with geotextile after removing the mold, and cure it naturally for 28 days, and then start the tests on the unit weight, compressive strength and frost resistance of the rockfill concrete body.

[0081] Application Example 2

[0082] The procedure is the same as that in Application Example 1. The slump of the mixture is controlled at 600 + 10 mm (subject to actual measurement), the water depth is controlled at 0.45 m, and the flow velocity is controlled at 0.5 m / s (subject to actual measurement). The others are the same as those in Application Example 1.

[0083] Application Example 3

[0084] The procedure is the same as that in Application Example 1. The slump of the mixture is controlled at 650 + 10 mm (subject to actual measurement), the water depth is controlled at 0.45 m, and the flow velocity is controlled at 0.5 m / s (subject to actual measurement). The others are the same as those in Application Example 1.

[0085] Application Example 4

[0086] The procedure is the same as that in Application Example 1. The slump of the mixture is controlled at 650 + 10 mm (subject to actual measurement), the water depth is controlled at 0.55 m, and the flow velocity is controlled at 0.5 m / s (subject to actual measurement). The others are the same as those in Application Example 1.

[0087] Application Example 5

[0088] The procedure is the same as that in Application Example 1. The slump of the mixture is controlled at 700 + 10 mm (subject to actual measurement), the water depth is controlled at 0.55 m, and the flow velocity is controlled at 0.5 m / s (subject to actual measurement). The others are the same as those in Application Example 1.

[0089] Test Results of Application Examples

[0090]

[0091] It can be seen from the application examples that different construction parameters will lead to different performances of underwater rockfill concrete, which can provide data support for engineering design. The void ratio of the rockfill can be used to calculate the amount of concrete, providing a basis for the design budget estimate. The unit weight of underwater rockfill concrete can provide a basis for stability calculation, while the 28-day compressive strength (in air and underwater), the land-water ratio, and the frost resistance grade all provide data support for the engineering quality of underwater rockfill concrete. At the same time, the test is carried out during the construction stage, which can provide a predictive evaluation of the construction quality for the construction unit, avoid engineering losses caused by blind underwater construction operations, and provide a guarantee for the normal operation and benefit of water conservancy projects. The economic and social benefits of this technical solution are very significant.

Claims

1. A water tank simulation test device and method for underwater rockfill concrete, characterized in that: include: It includes mobile vehicle, water tank system, underwater rockfill mold, casting system and lifting system. The water tank system comprises a water tank (14) which is arranged on the mobile vehicle; The underwater rockfill mold is a wooden mold groove (13) and is arranged inside a water tank (14), and the depth of the water tank (14) is greater than the depth of the mold. The pouring system is a small concrete delivery pump (10) which is arranged on a mobile vehicle. Hoisting system: It is an electric hoist (7) suspended on the mobile vehicle and used for hoisting the finished poured concrete test block.

2. The water tank simulation test device and method for underwater rockfill concrete according to claim 1, characterized in that: The mobile vehicle comprises a base plate (1), both ends of which are provided with vertical frames (4), and a crossbeam (6) is horizontally provided between the two vertical frames (4).

3. The water tank simulation test device and method for underwater rockfill concrete according to claim 1, characterized in that: The water tank (14) is arranged on an intermediate bracket welded to the base plate (1); the wooden mold groove (13) is arranged in the inner cavity of the water tank (14); and the wooden mold groove (13) is filled with piled stones.

4. The water tank simulation test device and method for underwater rockfill concrete according to claim 3, characterized in that: A reflux temporary storage tank (2) is provided on the base plate (1) located on the left side of the water tank (14); a side bracket is provided on the base plate (1) located on the right side of the water tank (14), and a temporary water storage tank (8) is provided on the side bracket.

5. The water tank simulation test device and method for underwater rockfill concrete according to claim 4, characterized in that: The water trough (14) and the temporary water storage tank (8) are both connected to a drainage pipe on the left side, and a solenoid valve (15) is installed on the drainage pipe. A flow rate sensor (16) is installed in the water trough (14) and the temporary water storage tank (8) located at the water inlet port of each drainage pipe.

6. The water tank simulation test device and method for underwater rockfill concrete according to claim 1, characterized in that: A rotating shaft (5) is installed on the crossbeam (6), a rotating arm (3) is fixed at the lower end of the rotating shaft (5), an electric hoist (7) is installed at one end of the rotating arm (3) away from the rotating shaft (5), and the electric hoist (7) is located directly above the wooden mold groove (13).

7. The water tank simulation test device and method for underwater rockfill concrete according to claim 1, characterized in that: The small concrete delivery pump (10) is arranged on the base plate 1 located on the temporary water tank (8).

8. The water tank simulation test device and method for underwater rockfill concrete according to claim 1, characterized in that: A circulating water pump (12) is arranged on the base plate (1) below the water tank (14); a water inlet pipe of the circulating water pump (12) is connected to the reflux temporary storage tank (2); and a drain pipe of the circulating water pump (12) is connected to the temporary storage water tank (8).

9. The experimental method of the water tank simulation test device for underwater rockfill concrete according to claims 1-9 is characterized in that: The steps include: Step S1: close the drain pipe at the tail end of the water tank (14), and fill water into the water tank (14) until it reaches a level close to the top of the water tank (14); Step S2: placing the prepared wooden formwork groove (13) into the water tank (14) in the form of actual engineering rockfill concrete, with the wooden formwork groove (13) being seated on the geotextile; Step S3: stacking rocks in the wooden mold groove (13), weighing the total mass of the rocks m, and then placing the rocks in the wooden mold groove (13), with the size of the rocks being larger at the bottom and smaller at the top, so as to reduce the gaps in the rocks; Step S4: concrete mixing. The mixing of underwater self-compacting concrete must maintain the anti-dispersion property of cement and ensure the slump expansion of the mixture. In order to ensure that the underwater rockfill is fully poured, the slump expansion value should not be less than 550mm. Step S5: Control the construction parameters, select the construction parameters that need to be tested before pouring; the slump expansion can be selected as 550mm, 600mm, 650mm, 700mm, the void ratio can be selected as 50-60%, and the pouring effect and cement loss of the test concrete mixture with different slump expansion can be selected; Step S6: Underwater pouring, the concrete mixture is conveyed to the funnel through a small concrete delivery pump (10), the outlet of the funnel is connected to a chute, and the discharge valve is opened to allow the mixture to flow into the rock pile of the underwater wooden mold groove (13) until the wooden mold groove (13) is filled, and the mixture is poured to above the top surface of the wooden mold groove (13) to form a small hill shape; Step S7: static curing. After 3-7 days of static curing, open the drain valve of the water tank (14) to drain the water; Step S8: The poured rockfill concrete body is hoisted out of the trench by the electric hoist 7 in cooperation with the crossbeam (6), and is covered with geotextile after demoulding, and naturally cured for 28 days, and its volume Vtotal is measured; Step S9: Perform strength test and frost resistance test on underwater rockfill concrete.

Images