A roadbed foam lightweight soil supplementary aeration carbonization device and its layout method

Abstract

The present invention discloses a roadbed foam lightweight soil supplementary aeration and carbonization device, comprising: an air intake pipe and several layers of air intake pipe networks, wherein each layer of air intake pipe networks is designed to be parallel to each other, and each layer of air intake pipe networks comprises: a two-dimensional planar pipe network connected horizontally and vertically, wherein the horizontal and vertical connection points of each two-dimensional planar pipe network are perpendicularly connected to several air intake pipes, and the connection between the air intake pipes and the two-dimensional planar pipe network is externally wrapped with a foam lightweight soil prefabricated member, and the two-dimensional planar pipe network is provided with several air outlet holes. The present invention uses hollow pipes instead of solid steel mesh, and the horizontal and vertical connection replaces the solid steel mesh, thereby reducing the load while improving the road surface strength.

Description

Technical Field

[0001] The invention discloses a roadbed foam lightweight soil supplementary aeration and carbonization device and a layout method, and relates to the field of road construction methods. Background Art

[0002] Based on CCUS (Carbon Dioxide Capture, Storage and Utilization) technology, carbonization curing of foamed lightweight soil samples with CO2 can increase the hydration rate and improve the early strength of foamed lightweight soil by introducing CO2 to participate in the hydration reaction. Studies have found that the carbonization products of stored CO2 have good stability, filling effect and nucleation effect. Through CO2 carbonization treatment, high-performance cement-based materials can be obtained in a short period of time. At the same time, it can utilize industrial CO2 emissions and reduce emissions to the atmosphere, which is of great significance to the development of a low-carbon economy, the reduction of carbon emissions, the mitigation of the greenhouse effect and the sustainable development of the concrete industry. However, in existing projects, the carbonization of foamed lightweight soil often relies on natural curing. The CO2 concentration in the air is low and it is difficult for it to penetrate into the roadbed concrete, resulting in a slow carbonization reaction and no significant improvement in the early strength of the foamed lightweight soil. Summary of the Invention

[0003] In view of the defects in the above-mentioned background technology, the present invention provides a roadbed foam lightweight soil supplementary aeration and carbonization device and a layout method, which are used to reduce the load while improving the road surface strength.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a roadbed foam lightweight soil supplementary aeration and carbonization device, including: an air inlet pipe and several layers of air adding pipe networks, each layer of air adding pipe networks is designed to be parallel between the upper and lower layers, and each layer of air adding pipe networks includes: horizontally and vertically connected to form a two-dimensional plane network, the horizontal and vertical connection points of each layer of the two-dimensional plane network are vertically connected to several air inlet pipes, the connection between the air inlet pipe and the two-dimensional plane network is wrapped with a foam lightweight soil prefabricated part on the outside, and several air outlet ends are arranged on the two-dimensional plane network, and several air outlet holes are arranged at the air outlet ends.

[0005] Furthermore, the air inlet pipe and the air filling pipe network adopt hollow GFRP pipes.

[0006] Furthermore, a valve is provided on the air intake pipe.

[0007] A method for laying out the above-mentioned roadbed foam lightweight soil supplementary aeration and carbonization device includes the following steps:

[0008] According to the conservation of stiffness, design the specifications of the air intake pipe and the air filling pipe network;

[0009] Calculate the spacing of the intake pipes based on the gas flow pressure loss;

[0010] Longitudinal layout design of gas pipe network;

[0011] Design the gas outlet end of the pipe wall.

[0012] Furthermore, based on the conservation of stiffness, the specification parameters of the intake pipe and the gas filling pipe network are designed, which specifically includes the following steps:

[0013] ∑E 筋 I 筋 =∑E 管 I 管

[0014] Determine the inner and outer diameters of the hollow tube:

[0015]

[0016] Among them, E 筋 is the Young's modulus of the steel bar, E 管 is the Young's modulus of the air intake pipe or the gas filling pipe network; a is the diameter of the steel bar; D is the outer diameter of the air intake pipe or the gas filling pipe network; d is the inner diameter of the air intake pipe or the gas filling pipe network;

[0017] I 筋 is: the moment of inertia of the steel cross section about the neutral axis of bending;

[0018] I 管 It is: the moment of inertia of the cross section of the intake pipe or gas filling pipe network about the bending neutral axis.

[0019] Furthermore, calculating the interval distance of the intake pipes according to the gas flow pressure loss specifically includes the following steps:

[0020]

[0021] L<2l

[0022] P 损 ≤0.5P0

[0023] Among them, P 损 is the gas pressure loss at the outlet of the gas filling pipe network, l is the intermediate parameter, f is the friction coefficient of CO2 gas flow, d is the inner diameter of the gas filling pipe network, ρ is the CO2 gas density, v0 is the initial flow velocity of CO2 gas entering the pipeline, L is the distance between adjacent inlet pipes, and P0 is the initial pressure value of CO2 gas;

[0024] According to the calculation, l is obtained, and P is satisfied. 损 When ≤0.5P0, the interval between two adjacent intake pipes is less than 2l, which can ensure that the air pressure at each location in the pipe is sufficient and the pressure at each location is not less than 50% of the initial air pressure.

[0025] Furthermore, the longitudinal layout design of the gas pipe network includes the following steps: the gas pipe network is respectively arranged on the surface layer, the middle layer and the bottom layer,

[0026] The surface layer is: lightweight foam soil is poured within 1m below the design elevation of the roadbed,

[0027] The middle layer is located below the design elevation of the roadbed and above the construction section.

[0028] The bottom layer is: within 1m above the bottom of the foam lightweight soil construction section.

[0029] Furthermore, the design of the gas outlet end of the pipe wall specifically includes: arranging the intervals between the gas outlet ends and designing the opening area of ​​the gas outlet holes at each gas outlet end;

[0030] Arrange the intervals between each outlet:

[0031] H 28d <h≤1.5H 28d

[0032] Where: h is the maximum distance between any two adjacent inlet and outlet ends, H 28d It is the carbonation depth of concrete after 28 days;

[0033] Design the opening area of ​​the air outlet holes at each outlet:

[0034]

[0035]

[0036]

[0037] Among them, v ix is the gas flow rate at the distance x from the outlet of the i-th inlet pipe,

[0038] P x is the gas pressure at x, and x<l, i is the number of intake pipes,

[0039] v iy is the gas flow rate at a distance y from the outlet of the i-th gas inlet pipe, and y<l, y>x, and x and y are in the same direction of the same gas pipe network;

[0040] s x is the opening area of ​​the outlet hole array at a distance x from the inlet pipe;

[0041] s y The opening area of ​​the outlet hole array at a distance y from the inlet pipe.

[0042] Furthermore, a foam lightweight soil prefabricated part is added to the outside of the air outlet of the pipe wall and cast using the same mix ratio as in the construction. This prevents blockage of the inner wall and increased pressure loss caused by slurry backflow during roadbed construction. At the same time, the carbonization channel is the same, and no additional adverse effects are caused on the outgassing of carbon dioxide. The casting of the prefabricated components is the same as the layered and block-by-block casting of foam lightweight soil during construction.

[0043] Beneficial effects: The present invention changes the pipe network material and selects GFRP aeration pipes to obtain aeration channels while solving the corrosion effect of traditional steel bars on carbonization; at the same time, the present invention improves the design and layout of the air intake main pipe to ensure carbonization in each area; improves the exhaust end to reduce the adverse effects caused by construction and pouring, and at the same time calculates the exhaust position and combines it with the air intake pipe to control carbonization. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the pipe network distribution of the present invention;

[0045] Figure 2 It is a detailed diagram of the pipe network of the present invention;

[0046] Figure 3 Schematic diagram of the intake manifold valve arrangement of the present invention;

[0047] Figure 4 This is a schematic diagram of the gas outlet design of the present invention;

[0048] Figure 5 Schematic diagram of the intake pipe interval of the present invention. DETAILED DESCRIPTION

[0049] The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are not intended to limit the scope of protection of the present invention.

[0050] like Figure 1 An embodiment described: A roadbed foam lightweight soil supplementary aeration and carbonization device includes: an air intake pipe 1 and several layers of air intake pipe networks 2, each layer of air intake pipe networks 2 is designed to be parallel above and below, and each layer of air intake pipe networks 2 includes: a two-dimensional plane network connected horizontally and vertically, the horizontal and vertical connection points of each layer of the two-dimensional plane network are vertically connected to several air intake pipes 1, the connection between the air intake pipe 1 and the two-dimensional plane network is externally wrapped with a foam lightweight soil prefabricated part 4, several air outlet ends 5 are arranged on the two-dimensional plane network, and several air outlet holes are arranged at the air outlet ends 5; the air intake pipe and the air intake pipe network adopt hollow GFRP pipes; a valve 3 is arranged on the air intake pipe for switching the air intake.

[0051] Example 2:

[0052] A method for laying out the above-mentioned roadbed foam lightweight soil supplementary aeration and carbonization device includes the following steps:

[0053] According to the conservation of stiffness, design the specifications of the air intake pipe and the air filling pipe network;

[0054] Calculate the spacing of the intake pipes based on the gas flow pressure loss;

[0055] Longitudinal layout design of gas pipe network;

[0056] Design the gas outlet end of the pipe wall.

[0057] In the design of the gas pipe network layout, since the original steel mesh is replaced, the overall plane layout of the pipe network should give priority to the bearing function of the roadbed. The hollow structure of the same weight can improve the bending strength to a certain extent. Therefore, the steel mesh under the normal design state is replaced equally while ensuring that its stress parameters are qualified. The specifications of the replaced GFRP gas pipe are obtained through the bending stiffness formula:

[0058]

[0059] The designed steel bar diameter is 12 mm, the inner diameter of the GFRP aeration pipe is 10 mm, and the steel bar Young's modulus is 2×10 5 MPa, the Young's modulus of FRP is 4×10 4 MPa, the required outer diameter of the GFRP aerated pipe is calculated to be about 18 mm; at this time, the mass of the pipe network per unit length is calculated, and it is found that the GFRP aerated pipe is about 40% lighter than the steel bar, achieving the goal of reducing the load.

[0060] In addition, considering the pressure loss in gas flow, there is a difference in pressure at each outlet. The farther away from the main pipe, the greater the pressure loss. There is a certain correlation between the carbonization depth H and the pressure:

[0061]

[0062] Among them, K g is the variable coefficient related to concrete parameters, which changes with the changes of concrete parameters;

[0063] a is the variable coefficient related to the physical parameters of the permeating gas, which changes with the changes in the physical parameters of the permeating gas;

[0064] p a is atmospheric pressure;

[0065] p0 is the initial pressure;

[0066] p is the pressure at the outlet;

[0067] t0 is the initial time of refueling;

[0068] t is the time for gas filling to be completed;

[0069] It can be seen that in order to ensure complete carbonization of each part, it is necessary to ensure that the pressure in each part of the pipeline is as uniform as possible, that is, the pressure at each end should not be too small, and requirements are made for the pressure loss during the transmission process, namely:

[0070] Since the longitudinal transmission distance is relatively small, the pressure loss in the main pipe and the local pressure loss in each part can be ignored. Based on the gas flow pressure loss, the calculation of the interval distance of the intake pipe includes the following steps:

[0071]

[0072] L<2l

[0073] P 损 ≤0.5P0

[0074] Among them, P 损 is the gas pressure loss at the outlet of the gas filling pipe network, l is the intermediate parameter, f is the friction coefficient of CO2 gas flow, d is the inner diameter of the gas filling pipe network, ρ is the CO2 gas density, v0 is the initial flow velocity of CO2 gas entering the pipeline, L is the distance between adjacent inlet pipes, and P0 is the initial pressure value of CO2 gas;

[0075] According to the calculation, l is obtained, and P is satisfied. 损 When the pressure is less than 0.5P0, the distance between two adjacent intake pipes is less than 2l, which can ensure that the air pressure at each location in the pipe is sufficient and the pressure at each location is not less than 50% of the initial pressure.

[0076] The longitudinal layout design of the gas pipe network includes the following steps: the gas pipe network is respectively arranged on the surface layer, the middle layer and the bottom layer,

[0077] The surface layer is: lightweight foam soil is poured within 1m below the design elevation of the roadbed,

[0078] The middle layer is located below the design elevation of the roadbed and above the construction section.

[0079] The bottom layer is: within 1m above the bottom of the foam lightweight soil construction section.

[0080] The design of the gas outlet end of the pipe wall specifically includes: arranging the intervals between the gas outlet ends and designing the opening area of ​​the gas outlet holes at each gas outlet end;

[0081] Arrange the intervals between each outlet:

[0082] H 28d <h≤1.5H 28d

[0083] Where: h is the maximum distance between any two air inlet and outlet ends, H 28dIt is the carbonation depth of concrete after 28 days;

[0084] Design the opening area of ​​the air outlet holes at each outlet:

[0085]

[0086]

[0087]

[0088] Among them, v ix is the gas flow rate at the distance x from the outlet of the i-th inlet pipe,

[0089] P x is the gas pressure at x, and x<l, i is the number of intake pipes,

[0090] v iy is the gas velocity at a distance y from the outlet of the i-th inlet pipe, and y<l, y>x,

[0091] s x is the opening area of ​​the outlet hole array at a distance x from the inlet pipe;

[0092] s y The opening area of ​​the outlet hole array at a distance y from the inlet pipe.

[0093] According to the carbonization depth test, the data H 28d , and the maximum spacing between each outlet is designed to ensure that the edges of the carbonized areas that can be completed by each hole overlap, so as to achieve the purpose of complete carbonization. For the maximum spacing h between any two outlets, the following requirements must be met:

[0094] H 28d <h≤1.5H 28d

[0095] In addition, in order to ensure that the low-pressure area at the end far from the main pipe obtains sufficient carbon dioxide flow, it is necessary to increase the opening area to obtain the same amount of carbon dioxide at a relatively low flow rate to complete carbonization.

[0096] In the layout design of the gas pipe network, strength design still needs to be referred to for the longitudinal layout. At the same time, valves can be installed on each pipe network in the middle of the roadbed. Since the top and bottom ends of the roadbed have higher strength requirements than the middle part, valves can be used for air intake control.

[0097] A foam lightweight soil prefabricated component is added to the outside of the air outlet of the pipe wall and cast using the same mix ratio as in construction; this prevents blockage of the inner wall and increased pressure loss caused by slurry backflow during roadbed construction. At the same time, the carbonization channel is the same, and no additional adverse effects are caused on the outgassing of carbon dioxide; the casting of prefabricated components is the same as the layered and block-by-block casting of foam lightweight soil during construction.

[0098] Example 3:

[0099] A laboratory used aerated lightweight soil as a roadbed fill material to construct a roadbed and its carbonization device. The design strength was ≥1.2 MPa, and the roadbed fill height was 4 m. The single fill area of ​​the aerated lightweight soil roadbed was 5.0 × 4.0 m, with a single fill height of 0.1 m. The roadbed was poured in three layers: lower, middle, and upper. The construction mix ratio for the aerated lightweight soil is shown in the table below.

[0100]

[0101] Note: The cement used is Conch brand PO42.5 ordinary Portland cement, the foaming agent used is HTW-1 composite foaming agent, and the foaming agent dilution ratio is 1:50.

[0102] Step 1: Determine the relevant design for GFRP gas pipe to replace the steel pipe mesh;

[0103] Step 2: Cut the outlet end and the hole wall opening of the GFRP gas pipe according to the design plan;

[0104] Step 3: Sleeve the precast concrete end as required and assemble the GFRP gas pipe;

[0105] Step 4: Lay the gas supply network in layers, connect the main gas pipe according to the design requirements, and then carry out the pouring operation;

[0106] Step 5: The pipe is subsequently ventilated and carbonized. This can be monitored in real time by adding a temperature sensor, etc. The middle layer valve can be closed at the right time for further control. During this period, the gas volume ratio and internal pressure are controlled as required.

[0107] According to the above construction steps, the foam lightweight soil is poured in layers and blocks. Due to the injection of carbon dioxide, the carbonization reaction of the lightweight foam soil is accelerated, which greatly improves the early strength of the poured roadbed, significantly shortens the maintenance time, and greatly improves the construction efficiency.

[0108] The present invention changes the pipe network material and selects GFRP aeration pipes to obtain aeration channels while solving the corrosion effect of traditional steel bars on carbonization. At the same time, the present invention improves the design and layout of the air intake main pipe to ensure carbonization in each area. The exhaust end is improved to reduce the adverse effects caused by construction and pouring. At the same time, the exhaust position is calculated and carbonization control is carried out in conjunction with the air intake pipe.

[0109] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for laying out a roadbed foam lightweight soil supplementary aeration carbonization device, characterized in that: A roadbed foam lightweight soil supplementary aeration carbonization device is used, comprising: an air inlet pipe and several layers of air adding pipe networks, wherein each layer of air adding pipe networks is designed to be parallel to each other, and each layer of air adding pipe networks comprises: a two-dimensional plane network connected horizontally and vertically, wherein the horizontal and vertical connection points of each two-dimensional plane network are vertically connected to several air inlet pipes, and the connection between the air inlet pipe and the two-dimensional plane network is wrapped with a foam lightweight soil prefabricated part, and the two-dimensional plane network is provided with several air outlet ends, and the air outlet ends are provided with several air outlet holes; The deployment method comprises the following steps: According to the conservation of stiffness, design the specifications of the air intake pipe and the air filling pipe network; Calculate the spacing of the intake pipes based on the gas flow pressure loss; The longitudinal layout design of the gas filling pipe network includes the following steps: the gas filling pipe network is respectively arranged on the surface layer, the middle layer and the bottom layer, Designing the gas outlet end of the pipe wall, wherein the designing the gas outlet end of the pipe wall specifically includes: arranging the intervals between the gas outlet ends and designing the opening area of ​​the gas outlet holes at each gas outlet end; Arrange the intervals between each outlet: ； Where: h is the maximum distance between any two adjacent inlet and outlet ends, It is the carbonation depth of concrete after 28 days; Design the opening area of ​​the air outlet holes at each outlet: ； ； ； in, is the gas flow rate at the distance x from the outlet of the i-th inlet pipe, is the gas pressure at x, and x<l, i is the number of intake pipes, is the gas velocity at a distance y from the outlet of the i-th inlet pipe, and y<l, y>x, is the opening area of ​​the outlet hole array at a distance x from the inlet pipe; The opening area of ​​the outlet hole array at a distance y from the inlet pipe.

2. The method for laying out a roadbed foam lightweight soil supplementary aeration carbonization device according to claim 1, characterized in that: The air inlet pipe and the air filling pipe network are hollow GFRP pipes.

3. The method for laying out a roadbed foam lightweight soil supplementary aeration carbonization device according to claim 1, characterized in that: A valve is provided on the air inlet pipe.

4. The method for laying out a roadbed foam lightweight soil supplementary aeration and carbonization device according to claim 1, characterized in that: According to the principle of stiffness conservation, the design of the specifications of the intake and filling pipe networks includes the following steps: according to , determine the inner and outer diameters of the hollow tube, the expression is: ； in, is the Young's modulus of the steel bar, is the Young's modulus of the air intake pipe or the air filling pipe network; is the diameter of the steel bar; The outer diameter of the air inlet pipe or the gas filling pipe network; The inner diameter of the air inlet pipe or the gas filling pipe network; I 筋 is: the moment of inertia of the steel cross section about the neutral axis of bending; I 管 It is: the moment of inertia of the cross section of the intake pipe or gas filling pipe network about the bending neutral axis.

5. The method for laying out a roadbed foam lightweight soil supplementary aeration and carbonization device according to claim 4, characterized in that: According to the gas flow pressure loss, the calculation of the interval distance of the intake pipe includes the following steps: ； L＜2l； ； in, is the gas pressure loss at the outlet of the gas pipe network, is the intermediate parameter, is the friction coefficient of CO2 gas flow, is the inner diameter of the gas pipe network, is the CO2 gas density, is the initial flow rate of CO2 gas entering the pipeline, L is the distance between adjacent intake pipes, is the initial pressure of CO2 gas.

6. The method for laying out a roadbed foam lightweight soil supplementary aeration and carbonization device according to claim 1, characterized in that: The surface layer is: lightweight foam soil is poured within 1m below the design elevation of the roadbed, The middle layer is located below the design elevation of the roadbed and above the construction section. The bottom layer is: within 1m above the bottom of the foam lightweight soil construction section.

7. The method for laying out a roadbed foam lightweight soil supplementary aeration and carbonization device according to claim 1, characterized in that: A foam lightweight soil prefabricated part is added to the outside of the air outlet of the pipe wall.

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