Green backfill method based on all-solid waste engineering soil

Abstract

The present invention discloses a green backfilling method based on all-solid waste engineering soil, and relates to the technical field of backfilling deep, narrow and long irregular spaces such as various trenches and fertilizer troughs in housing construction projects, road and bridge projects. It is composed of saturated surface dry-pressed alkali slag, carbide slag, phosphogypsum and slag in a specific particle size range, replacing traditional natural soil as the backfill matrix, and using alkaline materials such as alkali slag to stimulate the activity of slag materials. Under the action of appropriate amount of water, the material is prompted to undergo hydration and gelation reaction, further improving the performance of the material. While saving the cost of later maintenance and repair, it reduces environmental pollution and promotes the resource utilization of solid waste materials.

Description

Technical Field

[0001] The present invention relates to the technical field of backfilling deep, narrow and long irregular spaces such as various trenches and fertilizer troughs in housing construction projects and road and bridge projects, and in particular to a green backfilling method based on all-solid waste engineering soil. Background Art

[0002] In the construction process of infrastructure construction, a common construction link is to use construction waste, engineering excavation surplus soil, etc. as filling materials, and perform backfill operations through mechanical or manual compaction methods. However, for various deep and narrow trenches, fertilizer troughs and other irregular spaces in housing construction projects, road and bridge projects, traditional backfill materials and technologies have exposed significant limitations, such as the complexity of construction operations, low work efficiency, high overall costs, and difficulty in ensuring the density of backfill soil. These factors may cause a series of problems such as settlement, uneven settlement due to self-weight consolidation, and wet settlement. These problems not only increase the difficulty of later maintenance, but also cause huge economic losses and social impacts.

[0003] In order to solve the above problems, the existing technology uses fluidized solidified soil as a substitute for conventional backfill soil, by adding cement as a curing agent into the soil, and improving the physical and mechanical properties of the soil through chemical reactions after mixing. However, traditional fluidized solidified soil often uses engineering excavation surplus soil or ordinary loess, which to a certain extent causes irrational use of soil resources, destroys the dynamic equilibrium state of material energy conversion and exchange in the soil, and thus causes soil degradation or even depletion. At the same time, the fluidized solidified soil currently circulating on the market has relatively high costs from raw materials to construction.

[0004] In addition, given the urgent need of the cement industry to reduce carbon emissions and the limitations of the resource utilization of industrial solid waste, coupled with the problem that existing backfill materials and technologies are difficult to effectively improve construction quality in deep, narrow and non-standard space construction, there is an urgent need to develop a green and environmentally friendly backfill method suitable for backfill projects. Summary of the invention

[0005] The embodiment of the present invention provides a green backfill method based on all-solid waste engineering soil, which has the characteristic of enabling the backfill material to obtain strength equivalent to that of conventional backfill soil without adding cement. While saving the cost of subsequent maintenance and repair, it reduces environmental pollution and promotes the resource utilization of solid waste materials.

[0006] A green backfill method based on all-solid waste engineering soil adopts the following technical solutions:

[0007] A green backfill method based on all-solid waste engineering soil, wherein the all-solid waste engineering soil is mixed with filter press alkali residue, carbide residue, phosphogypsum and slag in proportion; the backfill method comprises the following steps:

[0008] S1. Mechanically crushing and screening the filter press alkali residue, carbide residue, phosphogypsum and slag to form coarse and fine aggregates with different particle sizes;

[0009] S2. Combining and forming graded materials according to the composition ratio of various coarse and fine aggregates;

[0010] S3. Determine the optimum moisture content of the solid waste engineering soil through compaction test;

[0011] S4. Layered backfilling: During construction, backfill in layers according to the thickness of each layer of 200mm-300mm, and pay attention to the uniform distribution of materials in each layer;

[0012] S5. When backfilling, use multifunctional automatic control atomization protection device to carry out construction around the trench and fertilizer tank;

[0013] S6. Compacting: After each layer is laid, compact it as you fill it;

[0014] S7. Construction is completed when backfilling reaches the designed elevation;

[0015] Filter press alkali residue, carbide slag, and phosphogypsum with a particle size of 0.1-0.5 mm account for 15%-25%;

[0016] Filter press alkali residue, carbide slag and phosphogypsum with a particle size of 0.5-1mm account for 25%-35%;

[0017] Filter press alkali residue, carbide slag, and phosphogypsum with a particle size of 1-1.9 mm account for 20%-30%;

[0018] The proportions of filter press alkali slag, carbide slag and phosphogypsum of each particle size are 3:3:4 respectively.

[0019] The total mass of slag with a particle size of 0.01-4.75 mm, filter press alkali slag, carbide slag, phosphogypsum and slag is 100%.

[0020] Furthermore, the alkali filter residue, carbide slag, phosphogypsum and slag need to be dried before mixing and used, and the filling material is in a state of surface dryness and saturation, and all the internal pores are saturated with water.

[0021] Furthermore, the multifunctional automatic control mist protection device includes a mist generation system, an automatic control system and a protection device. The automatic control system can detect the moisture content of the solid waste engineering soil and can control the mist generation system to replenish water to the solid waste engineering soil. The protection device is a protective railing on the top of the foundation pit.

[0022] Furthermore, the all-solid waste engineering soil utilizes alkali slag materials to stimulate the activity of slag materials. Under the action of water, the hydrated gel causes the backfill material to have the strength of conventional fill soil.

[0023] Furthermore, in step S2, the mixing method of various coarse and fine aggregates is dry mixing, which can be done by on-site mixing or factory pre-mixing.

[0024] Furthermore, in step S6, an impact compactor or a vibrating roller is used to compact the mixed soil in layers to ensure the density and flatness of the mixed soil.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] By replacing traditional natural soil with industrial solid waste materials such as filter press alkali slag, carbide slag, phosphogypsum and slag in a specific particle size range as the backfill matrix, the activity of the slag material is stimulated by alkaline materials such as alkali slag, and the material is caused to undergo hydration and gelation reaction under the action of appropriate amount of water, which further improves the performance of the material. The backfill material can obtain the same strength as conventional backfill soil without adding cement. While saving the cost of later maintenance and repair, it reduces environmental pollution and promotes the resource utilization of solid waste materials. In addition, by setting up a multifunctional automatic control atomization protection device around the trench, it can not only replenish water, but also suppress dust, ensuring that the backfill material reaches the optimal moisture content, thereby improving the backfill effect and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present invention, and do not constitute a limitation of the present invention. In the drawings:

[0028] Figure 1 To embody the process flow chart of the present invention;

[0029] Figure 2 To embody the cross-sectional schematic diagram of the present invention;

[0030] Figure 3 It is a schematic plan view showing an implementation of the present invention.

[0031] Explanation of the accompanying drawings: 1. All-solid waste engineering soil; 2. Building cushion layer; 3. Building raft foundation; 4. Building exterior wall; 5. Multifunctional automated controlled atomization protection device; 6. Foundation pit slope. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0033] A full-solid waste engineering soil comprises filter press slag, carbide slag, phosphogypsum and slag.

[0034] Filter press alkali slag, carbide slag and phosphogypsum with a particle size of 0.1-0.5mm account for 15%-25%.

[0035] Filter press alkali slag, carbide slag and phosphogypsum with a particle size of 0.5-1mm account for 25%-35%.

[0036] Filter press alkali slag, carbide slag and phosphogypsum with a particle size of 1-1.9mm account for 20%-30%.

[0037] The remainder is slag with a particle size of 0.01-4.75 mm.

[0038] The proportion of filter press alkali residue, carbide slag and phosphogypsum of each particle size is 3:3:4. The proportion of particle grading control of each component is weight ratio.

[0039] Filter press slag, carbide slag, phosphogypsum and slag are mechanically crushed and sieved to form coarse and fine aggregates of different particle sizes. Filter press slag, carbide slag, phosphogypsum and slag need to be dried before use. The surface of the material is dry and saturated with water, and all the internal pores are saturated with water, but there is no moisture on the surface.

[0040] Before drying filter press slag, carbide slag, phosphogypsum and slag, ensure that the material is in a state that is conducive to water absorption. For example, try to make the particle size uniform to avoid uneven water absorption due to large differences in particle size. For agglomerated particles, they can be broken up and separated by slight mechanical stirring or screening to increase the contact area between particles and water.

[0041] The material is dried by segmented drying, which can better control the moisture state. Taking the drying of slag containing a certain amount of moisture as an example, in the initial stage, a high temperature (such as 120-150℃) can be used to quickly remove a large amount of free water on the surface of the material. This stage generally lasts for a short time. For example, for a thinner slag layer (thickness less than 5cm), it can last for 15-30min. When the free water on the surface is basically removed, the temperature is reduced to 80-100℃, so that the moisture in the internal pores slowly moves to the surface under mild conditions. This stage takes a relatively long time and may take 1-3h, depending on the volume and pore structure of the material. During the drying process, over-drying is not allowed. When the surface of the material reaches a dry state, the drying operation needs to be stopped. The surface dryness of the material can be judged by observing the surface of the material (such as matte surface, no trace of moisture) or using a humidity sensor. For example, an infrared humidity sensor is used to monitor the surface of the material. When the humidity sensor reading is lower than a certain threshold, the surface is considered dry. At this time, the internal pores of the material may still retain a certain amount of moisture, creating conditions for subsequent water absorption and saturation.

[0042] After drying, place the material in an environment with suitable temperature to promote water absorption. The material absorbs moisture in the air and makes all the pores inside the material saturated with water. If the material temperature is too high, the moisture will easily condense on the surface and cannot enter the internal pores. Generally speaking, it is more appropriate to cool the material temperature to room temperature (20-25℃).

[0043] Ventilation is required during the drying process. The main purpose of ventilation is to remove the evaporated moisture on the surface of the material and adjust the humidity and temperature of the drying environment. Reasonable ventilation speed and method can effectively control the drying process of the material. For granular materials, a uniform ventilation method is adopted, and the ventilation speed can be controlled at 0.3-0.8m / s to ensure that ventilation can reach all surfaces of the material.

[0044] Reference Figure 1 , Figure 2 and Figure 3 A building raft foundation 3 is arranged above the building cushion layer 2, and a building outer wall 4 is arranged above the building raft foundation 3. A groove is formed between the building outer wall 4 and the foundation pit slope 6, and the groove is backfilled with solid waste engineering soil 1. A multifunctional automatic control atomization protection device 5 is arranged above the foundation pit slope 6.

[0045] A green backfill method based on all-solid waste engineering soil, comprising the following steps:

[0046] S1. Take filter press alkali residue, carbide slag, phosphogypsum and slag that meet the raw material requirements, crush them mechanically and then sieve them to form coarse and fine aggregates of different particle sizes.

[0047] Pressed alkali residue, carbide slag, phosphogypsum and slag must be dried before use. The materials are all in a state of surface dryness and saturation, with all internal pores saturated with water, but no moisture on the surface.

[0048] Raw materials need to be tested before mechanical crushing to determine whether they meet the basic requirements for backfill grading. Chemical analysis is used to detect the chemical composition of alkali slag, including the content of harmful substances (such as heavy metals) and the proportion of main components. Physical properties such as moisture content and specific gravity are also tested. These initial test data can provide reference for subsequent drying, crushing and screening processes, and clarify the direction of adjustment. If the raw materials themselves do not meet the basic chemical or physical requirements, it may be necessary to reconsider their applicability or take special pretreatment measures.

[0049] S2. According to the composition ratio of various coarse and fine aggregates, graded materials are formed.

[0050] The particle grading of each component is controlled by weight, and the mixing method is dry mixing, which can be done on-site or pre-mixed in a factory.

[0051] S3. Determine the optimum moisture content through compaction test.

[0052] S4. Layered backfilling: During construction, backfill in layers with a thickness of 200mm-300mm per layer, and pay attention to the uniform distribution of materials in each layer.

[0053] S5. Install a multifunctional automatic control mist placement device 5 around the trench and fertilizer tank. During backfilling, the multifunctional automatic control mist protection device 5 automatically sprays the backfill material. The multifunctional automatic control mist protection device 5 can serve as a protective railing on the top of the foundation pit. The mist spray system set inside plays a role in dust suppression and water replenishment, ensuring that the optimal moisture content of the material is achieved during backfilling.

[0054] The multifunctional automatic control atomization protection device 5 can automatically spray the backfill material at a fixed time according to the optimal moisture content determined in the early stage. The alkaline materials such as alkali slag are used to stimulate the activity of the slag material. Under the action of part of the water, the hydration and gelation make the backfill material have the strength of conventional backfill soil. At the same time, the water flow is atomized to avoid excessive water volume, which will cause the backfill material to agglomerate.

[0055] S6. Compaction: After each layer is laid, compact it as you fill it. Use impact compactors, vibrating rollers and other equipment to compact the layers. Reasonably select the rolling vibration frequency to ensure the density and flatness of the mixture.

[0056] S7. Construction is completed when backfilling reaches the designed elevation. No curing is required for backfilling construction using this method.

[0057] The multifunctional automatic control mist protection device includes a mist generation system, an automatic control system and a protection structure. The mist generation system includes a water storage tank, a water pump, a mist nozzle and a connecting pipe. The water in the water storage tank is transported to the mist nozzle through the connecting pipe by the water pump to form fine mist droplets.

[0058] The automatic control system includes a sensor and a control center. The sensor is a non-contact moisture sensor. The sensor does not need to be in direct contact with the backfill material, but measures the moisture content through infrared or microwave technologies. For backfill materials with a flat surface (such as the material used in this method), the non-contact sensor can be installed at a certain height (such as 1-2m from the material surface) to scan the moisture content of a large area of ​​the material. The moisture content is calculated by using the absorption characteristics of water to infrared or microwaves of a specific wavelength. The control center receives the data from the sensor and makes judgments and decisions based on the preset moisture content target value.

[0059] For example, if the moisture content of the backfill material is detected to be lower than the target value, the control center will issue a command to start the atomization system to replenish water; when the moisture content reaches the target value, the control center will control the atomization system to stop spraying. The control center can also set the operating parameters of the atomization system, such as spraying time, atomization nozzle rotation speed, etc.

[0060] The control center can adjust the atomization system according to the actual effect after spraying. During the spraying process, the sensor will continue to monitor the changes in the moisture content of the backfill material and feed the data back to the control center. If it is found that the moisture content increases too slowly or too quickly after spraying, the control unit can adjust the flow rate of the water pump, the rotation speed of the nozzle and other parameters to achieve the ideal spraying effect. For example, if the moisture content of the backfill material in a certain area increases too quickly after spraying, the control center can reduce the spraying intensity of the nozzle in that area, or shorten the spraying time. The protective structure is a guardrail on the top of the foundation pit, which can be used for protection of the edge of the foundation pit. The atomizing nozzle is installed on the guardrail.

[0061] The present invention replaces traditional natural soil with industrial solid waste materials such as filter press alkali slag, carbide slag, phosphogypsum and slag in a specific particle size range as the backfill matrix, and uses alkaline materials such as alkali slag to stimulate the activity of slag materials. Under the action of an appropriate amount of water, the material is prompted to undergo a hydration and gelation reaction, thereby further improving the performance of the material. The backfill material can obtain a strength equivalent to that of conventional backfill soil without adding cement. While saving the cost of later maintenance and repair, it reduces environmental pollution and promotes the resource utilization of solid waste materials. In addition, by arranging a multifunctional automatic control atomization protection device around the groove, it can not only replenish water, but also suppress dust, ensuring that the backfill material reaches the optimal moisture content, thereby improving the backfill effect and stability.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A green backfill method based on all-solid waste engineering soil, characterized in that: The full solid waste engineering soil is made by mixing filter alkali residue, carbide residue, phosphogypsum and slag in proportion; the backfill method includes the following steps: S1. Mechanically crushing and screening the filter press alkali residue, carbide residue, phosphogypsum and slag to form coarse and fine aggregates with different particle sizes; S2. Combining and forming graded materials according to the composition ratio of various coarse and fine aggregates; S3. Determine the optimum moisture content of the solid waste engineering soil through compaction test; S4. Layered backfilling: During construction, backfill in layers according to the thickness of each layer of 200mm-300mm, and pay attention to the uniform distribution of materials in each layer; S5. When backfilling, use multifunctional automatic control atomization protection device to carry out construction around the trench and fertilizer tank; S6. Compacting: After each layer is laid, compact it as you fill it; S7. Construction is completed when backfilling reaches the designed elevation; Filter press alkali residue, carbide slag, and phosphogypsum with a particle size of 0.1-0.5 mm account for 15%-25%; Filter press alkali residue, carbide slag and phosphogypsum with a particle size of 0.5-1mm account for 25%-35%; Filter press alkali residue, carbide slag, and phosphogypsum with a particle size of 1-1.9 mm account for 20%-30%; The balance is slag with a particle size of 0.01-4.75 mm; The proportions of filter press alkali residue, carbide slag and phosphogypsum of each particle size are 3:3:4 respectively; Alkali filter residue, carbide slag, phosphogypsum and slag must be dried before mixing. The filling material should be in a dry and saturated state, and all internal pores should be saturated with water.

2. The green backfill method based on all-solid waste engineering soil according to claim 1 is characterized in that: The multifunctional automatic control mist protection device includes a mist generation system, an automatic control system and a protection device. The automatic control system can detect the moisture content of the solid waste engineering soil and can control the mist generation system to replenish water to the solid waste engineering soil. The protection device is a protective railing on the top of the foundation pit.

3. The green backfill method based on all-solid waste engineering soil according to claim 2 is characterized in that: All-solid waste engineering soil uses alkali slag materials to stimulate the activity of slag materials. Under the action of water, the hydrated gel makes the backfill material have the strength of conventional fill.

4. The green backfill method based on all-solid waste engineering soil according to claim 1 is characterized in that: In step S2, the mixing method of various coarse and fine aggregates is dry mixing, which can be done on-site or pre-mixed in a factory.

5. The green backfill method based on all-solid waste engineering soil according to claim 1 is characterized in that: In step S6, an impact compactor or a vibrating roller is used to compact the mixed soil in layers to ensure the density and flatness of the mixed soil.

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