Artificial anti-seepage water-resisting layer of strip mine dump and construction method of artificial anti-seepage water-resisting layer

Abstract

The invention provides an artificial anti-seepage water-resisting layer of a strip mine dump and a construction method of the artificial anti-seepage water-resisting layer. The artificial anti-seepage water-resisting layer of the strip mine dump comprises N alkali-activated material layers which are sequentially laid on a base layer of an area to be constructed from bottom to top. Wherein N is greater than or equal to 2, and the alkali-activated material comprises a cementing material, an alkali activator and waste rock aggregate; the total weight of the cementing material is 100%, and the cementing material comprises 20%-80% of mudstone powder and 20%-80% of slag powder. The artificial anti-seepage water-resisting layer is high in compressive strength, low in permeability and excellent in disturbance resistance and cracking resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ecological restoration of mines, and particularly relates to an artificial anti-seepage water-resisting layer for a dump of an open-pit mine and a construction method thereof. BACKGROUND

[0002] The dump of an open-pit coal mine is usually directly piled up by stripping materials such as stripped rock strata, mudstone and sandstone, and has loose material structure, uneven grain size distribution, high overall porosity and strong permeability. The runoff on the surface of the dump easily seeps along the cracks, which makes it difficult to retain water in the dump area, is not conducive to the growth of vegetation and ecological restoration, and may also pollute the aquifer below the mine area for a long time, endangering the safety of groundwater resources. In addition, the dump itself or mine area solid waste such as mudstone and sandstone cannot be fully utilized due to insufficient strength and activity, and a large amount of stacking will also cause environmental pressure.

[0003] To improve the permeability and water storage capacity of the dump, the traditional method is to use a cement-based, bentonite-based or geotextile composite anti-seepage layer. The cement-based material has high strength after solidification, but has high energy consumption and carbon emissions in the production and transportation process, and performs poorly in crack self-healing ability and chemical corrosion resistance; the bentonite (or clay) anti-seepage layer uses its swelling to close the pores, but the in-situ construction process is complex, and has high requirements for material selection, transportation and on-site laying environment, and the dry-wet cycle in the later period easily causes the expansion of cracks in the bentonite, affecting the long-term anti-seepage effect; although the membrane material layer such as geotextile has high construction speed, it has strict requirements for the flatness of the base, welding quality and durability, and has problems such as high construction difficulty, easy aging and damage, and high maintenance cost.

[0004] Geopolymer materials have been widely concerned due to their good mechanical properties and environmental friendly characteristics. Through alkali activation reaction, a dense three-dimensional network structure is formed, the porosity and permeability coefficient are low, and the water and harmful fluid penetration can be effectively blocked. However, due to the influence of region and source, some raw material components may cause unstable performance of the material; when the existing geopolymer material is used for reconstruction of the water-resisting layer, especially in the environment with dynamic load or large temperature difference, cracks in the material structure and evolution of pore network are caused, resulting in cracking. The cracks form water seepage channels, reducing the waterproof effect. Therefore, in addition to the requirements of low permeability and good compressive strength, the water-resisting layer material also needs to have high anti-disturbance ability, durability and anti-shrinkage. SUMMARY

[0005] Based on the above analysis, this invention provides an artificial seepage-proof and waterproof layer for open-pit coal mine spoil heaps and its construction method, addressing at least one of the following technical problems in existing open-pit mine spoil heaps: low material strength, poor waterproofing performance due to unstable performance and easy cracking under dynamic loads or high-temperature environments, low utilization rate of solid waste resources in the open-pit mine spoil heap itself or the mining area, and high difficulty and efficiency in on-site construction of artificial waterproof layers. The artificial seepage-proof and waterproof layer of this invention features high strength, low permeability, resistance to disturbance, resistance to cracking, and is environmentally friendly. The construction method of this invention can fully utilize the resources of the mine spoil heap itself or the mining area's solid waste resources, and can achieve continuous layered construction on-site, resulting in low cost and high efficiency.

[0006] In a first aspect, the present invention provides an artificial seepage-proof and water-resistant layer for open-pit mine spoil heaps, comprising N alkali-activated material layers laid sequentially from bottom to top on the base layer of the area to be constructed; wherein, N≥2, the alkali-activated material includes cementitious material, alkali activator and waste rock aggregate; based on the total weight of the cementitious material as 100%, the cementitious material includes 20%~80% mudstone powder and 20%~80% slag powder.

[0007] The artificial seepage-proof and waterproof layer of the open-pit mine spoil heap of this invention uses an alkali-activated material, which combines mudstone and slag as a cementing material, thereby improving the ductility and strength of the alkali-activated material. The waste rock aggregate comes from the waste rock produced in the mining area (e.g., open-pit mine spoil heap) and has good compatibility with the cementing material of this invention, which helps to improve the overall performance of the material. At the same time, it can also improve the resource utilization rate of waste rock in the mining area and reduce costs.

[0008] In this invention, the base layer of the area to be constructed can be a planar base layer or a sloping base layer with a certain slope.

[0009] In this invention, the weight percentage of mudstone powder in the cementitious material can be 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, or any value between them.

[0010] In this invention, the weight percentage of slag powder in the cementitious material can be 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, or any value between them.

[0011] According to some embodiments of the present invention, the cementing material comprises 30% to 60% mudstone powder and 40% to 70% slag powder, based on the total weight of the cementing material as 100%; or the cementing material is composed of 30% to 60% mudstone powder and 40% to 70% slag powder.

[0012] According to some embodiments of the present invention, the cementitious material comprises 30% to 40% mudstone powder and 60% to 70% slag powder, based on the total weight of the cementitious material as 100%; or, the cementitious material is composed of 30% to 40% mudstone powder and 60% to 70% slag powder.

[0013] According to some embodiments of the present invention, the weight ratio of the alkali activator to the cementitious material is 1:(1~3), for example, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3 or any value between them. According to some embodiments of the present invention, the mass ratio of the alkali activator to the cementitious material is 1:(1~2), preferably 1:(1~1.5).

[0014] According to some embodiments of the present invention, the modulus of the alkali activator is 0.8 to 1.2. Controlling the modulus of the activator can ensure sufficient alkali activation reaction and guarantee the activity of the cementitious material.

[0015] According to some embodiments of the present invention, the alkaline activator comprises a mixture of sodium hydroxide and water glass. According to some embodiments of the present invention, the mass ratio of sodium hydroxide to water glass in the alkaline activator is 1:(3.5~4.5), for example, 1:3.5, 1:3.8, 1:4.0, 1:4.2, 1:4.5, etc. In some embodiments, the mass ratio of sodium hydroxide to water glass in the alkaline activator is 1:(3.8~4.2).

[0016] According to some embodiments of the present invention, the weight ratio of the waste stone aggregate to the cementitious material is (2.0 ~ 4.0): 1, for example, 2: 1, 2.2: 1, 2.5: 1, 2.8: 1, 3: 1, 3.2: 1, 3.5: 1, 3.8: 1, 4: 1 or any value between them, preferably (2.5 ~ 3.5): 1.

[0017] According to some embodiments of the present invention, the average particle size of the mudstone powder is ≤ 1 mm. According to some embodiments of the present invention, the average particle size of the mudstone powder is 0.1~1 mm. According to some embodiments of the present invention, the average particle size of the mudstone powder is 0.3~0.8 mm. According to some embodiments of the present invention, the average particle size of the mudstone powder is 0.4~0.6 mm. In some embodiments, the average particle size of the mudstone powder is 0.5 mm.

[0018] According to some embodiments of the present invention, the specific surface area of ​​the mudstone powder is ≥450 m². 2 / kg. In some embodiments, the specific surface area of ​​the mudstone powder is 450~500 m². 2 / kg.

[0019] According to some embodiments of the present invention, the slag powder includes slag powder of grade S75 or higher, such as S75 grade slag powder, S95 grade slag powder, S105 grade slag powder, etc. In this invention, the grade of the slag powder is based on the grade standard specified in GB / T18046-2008.

[0020] According to some embodiments of the present invention, the average particle size of the slag powder is ≤45 μm. In some embodiments, the average particle size of the slag powder is 30~45 μm. In some embodiments, the average particle size of the slag powder is 35~40 μm.

[0021] According to some embodiments of the present invention, the waste rock aggregate is selected from sandstone stripped from the ore body. "Sandstone stripped from the ore body" refers to sandstone layers stripped from above or around the ore body during the mining process.

[0022] According to some embodiments of the present invention, the main components of the waste rock aggregate include SiO2, Al2O3, and CaO. In some embodiments, the SiO2 content in the waste rock aggregate is 60-80 wt%. In some embodiments, the Al2O3 content in the waste rock aggregate is 10-20 wt%. In some embodiments, the CaO content in the waste rock aggregate is 1-10 wt%. According to some embodiments of the present invention, the waste rock aggregate also contains MgO, Fe, and K2O.

[0023] According to some embodiments of the present invention, the mud content of the waste rock aggregate is ≤0.5wt%. According to some embodiments of the present invention, the mud content of the waste rock aggregate is ≤0.4wt%. According to some embodiments of the present invention, the mud content of the waste rock aggregate is ≤0.3wt%.

[0024] According to some embodiments of the present invention, the average particle size of the waste rock aggregate is ≤1.5 mm. In some embodiments, the average particle size of the waste rock aggregate is 0.1~1.5 mm. In some embodiments, the average particle size of the waste rock aggregate is 0.5~1.5 mm. In some embodiments, the average particle size of the waste rock aggregate is 0.8~1.2 mm. In some embodiments, the average particle size of the waste rock aggregate is 1.0 mm. Controlling the particle size of the waste rock aggregate within a suitable range can prevent increased cracking and increased permeability due to excessively large particles.

[0025] According to some embodiments of the present invention, the alkali-activated material further includes water. In some embodiments, the water-to-binder ratio of the alkali-activated material is 1:(0.5~1.5), preferably 1:(0.8~1.2). In the present invention, controlling the water-to-binder ratio within a suitable range can balance the strength, flowability, and permeability of the material.

[0026] According to some embodiments of the present invention, the alkali activating material comprises, by weight, 560-2240 parts of cementitious material, 4000-5600 parts of waste stone aggregate, 1200-1800 parts of alkali activator, and 1000-1500 parts of water.

[0027] In this invention, the weight percentage of the cementitious material in the alkali-activated material can be 560 parts, 600 parts, 800 parts, 1000 parts, 1200 parts, 1300 parts, 1350 parts, 1400 parts, 1450 parts, 1500 parts, 1600 parts, 1800 parts, 2000 parts, 2200 parts, 2240 parts, or any value between them. In some embodiments, the weight percentage of the cementitious material in the alkali-activated material is 600-2200 parts. In some embodiments, the weight percentage of the cementitious material in the alkali-activated material is 800-2000 parts. In some embodiments, the weight percentage of the cementitious material in the alkali-activated material is 1000-1800 parts. In some embodiments, the weight percentage of the cementitious material in the alkali-activated material is 1200-1600 parts. In some embodiments, the weight percentage of the cementitious material in the alkali-activated material is 1300-1500 parts. In some embodiments, the weight percentage of the cementitious material in the alkali-activated material is 1350-1450 parts.

[0028] In this invention, the weight percentage of waste rock aggregate in the alkali-activated material can be 4000 parts, 4050 parts, 4100 parts, 4150 parts, 4200 parts, 4250 parts, 4300 parts, 4350 parts, 4400 parts, 4450 parts, 4500 parts, 4600 parts, 4700 parts, 4800 parts, 4900 parts, 5000 parts, 5100 parts, 5200 parts, 5300 parts, 5400 parts, 5500 parts, 5600 parts, or any value between them. According to some embodiments of the invention, the weight percentage of waste rock aggregate in the alkali-activated material is 4050-4450 parts. According to some embodiments of the invention, the weight percentage of waste rock aggregate in the alkali-activated material is 4100-4300 parts. According to some embodiments of the invention, the weight percentage of waste rock aggregate in the alkali-activated material is 4150-4250 parts.

[0029] In this invention, the weight percentage of the alkali activator in the alkali-activated material can be 1200 parts, 1300 parts, 1400 parts, 1450 parts, 1475 parts, 1500 parts, 1550 parts, 1600 parts, 1700 parts, 1800 parts, or any value between them. According to some embodiments of the invention, the weight percentage of the alkali activator in the alkali-activated material is 1300-1700 parts. According to some embodiments of the invention, the weight percentage of the alkali activator in the alkali-activated material is 1400-1600 parts. According to some embodiments of the invention, the weight percentage of the alkali activator in the alkali-activated material is 1450-1550 parts.

[0030] In this invention, the weight percentage of water in the alkali-activated material can be 1000 parts, 1050 parts, 1100 parts, 1200 parts, 1250 parts, 1300 parts, 1350 parts, 1400 parts, 1500 parts, or any value between them. According to some embodiments of the invention, the weight percentage of water in the alkali-activated material is 1300-1400 parts. According to some embodiments of the invention, the weight percentage of water in the alkali-activated material is 1300-1350 parts.

[0031] According to some preferred embodiments of the present invention, the alkali-activated material comprises, by weight: 420-840 parts mudstone powder, 560-980 parts slag powder, 4000-4400 parts waste stone fine aggregate, 1100-1200 parts water glass, 280-300 parts sodium hydroxide, and 1300-1350 parts water.

[0032] According to some embodiments of the present invention, the alkali-activated material further includes a quick-setting agent, such as a calcium aluminate early-strength agent.

[0033] According to some embodiments of the present invention, the artificial seepage-proof and waterproof layer of the open-pit mine spoil heap further includes a seepage-proof wall disposed around the N alkali-activated material layers.

[0034] According to some embodiments of the present invention, the seepage barrier is a C30 reinforced concrete seepage barrier. In some embodiments, the height of the seepage barrier is 1.4~1.6m, preferably 1.45~1.55m. In some embodiments, the thickness of the seepage barrier is 0.4~0.6m, preferably 0.45~0.55m. In some embodiments, the permeability of the seepage barrier is ≤1×10⁻⁶. -16 m 2 In some embodiments, the permeability of the impermeable wall is 0.5 × 10⁻⁶. -16 ~1×10 -16 m 2 In some embodiments, the permeability of the impermeable wall is 0.8 × 10⁻⁶. -16 ~1×10 -16 m 2 In some embodiments, the permeability of the impermeable wall is ≤0.8×10⁻⁶. -16 m 2 In some embodiments, the permeability of the impermeable wall is ≤0.5×10⁻⁶. -16 m 2 .

[0035] According to some embodiments of the present invention, the seepage barrier wall is internally provided with reinforcing mesh. In some embodiments, the spacing of the reinforcing mesh is ≤200mm. In some embodiments, the spacing of the reinforcing mesh is 100~200mm. In some embodiments, the spacing of the reinforcing mesh is 100~150mm. In some embodiments, the spacing of the reinforcing mesh is 150~200mm. In some embodiments, the spacing of the reinforcing mesh is ≤150mm. In some embodiments, the spacing of the reinforcing mesh is ≤100mm.

[0036] According to some embodiments of the present invention, the thickness of each of the alkali-activated material layers is independently 15-25 cm. According to some embodiments of the present invention, the thickness of the N alkali-activated material layers is the same.

[0037] According to some embodiments of the present invention, the compacted thickness of the artificial impermeable waterproof layer is not less than 0.6m.

[0038] Secondly, the present invention provides a method for constructing an artificial seepage-proof and waterproof layer in an open-pit mine spoil heap as described in the first aspect, which includes the following steps: (1) The area to be constructed is vibrated and compacted and / or leveled to obtain the base layer; (2) N layers of alkali-activated material are laid sequentially from bottom to top on the base layer to obtain an artificial seepage-proof and water-proof layer; wherein, N≥2, the alkali-activated material includes cementitious material, alkali activator and waste rock aggregate; based on the total weight of the cementitious material as 100%, the cementitious material includes 20%~80% mudstone powder and 20%~80% slag powder.

[0039] According to some embodiments of the present invention, the method for constructing the artificial seepage-proof and water-resistant layer of the open-pit mine spoil heap includes the following steps: (1) The area to be constructed is vibrated and compacted and / or leveled to obtain the base layer; (2) A mold is erected on the base layer, the alkali activating material is injected into the mold, and after vibration compaction and curing, the first alkali activating material layer is obtained; (3) After the N-1th alkali-activated material layer is compacted and / or leveled, a mold is set up, the alkali-activated material is injected into the mold, and after compaction and curing, the Nth alkali-activated material layer is obtained. (4) Construct the seepage barrier wall around the N alkali-activated material layers.

[0040] According to some preferred embodiments of the present invention, steps (2) and (3) further include: after curing, roughening the surface of the alkali-activated material layer. In some embodiments, the roughness of the roughening treatment is ≥0.5 mm, preferably 1~2 mm.

[0041] According to some embodiments of the present invention, the vibration frequency in the vibration compaction treatment is not less than 2000 times / minute, for example, 2000-3000 times / minute, preferably 2500-3000 times / minute, and more preferably 2700-2800 times / minute. According to some embodiments of the present invention, the vibration compaction time for a single layer in the vibration compaction treatment is ≥5 minutes, preferably 5-15 minutes. According to some embodiments of the present invention, the density in the vibration compaction treatment is ≥90%, preferably ≥96%. Under the vibration conditions (vibration frequency and density) of the present invention, the slurry can fully fill the gaps between waste stone aggregates, forming a dense microstructure (scanning electron microscopy showing a porosity ≤3%).

[0042] According to some embodiments of the present invention, the flatness error of the flattening process is -5 to 5 mm.

[0043] According to some embodiments of the present invention, curing is performed within 1 hour after the compaction treatment.

[0044] According to some embodiments of the present invention, the curing conditions include: humidity ≥ 50%, preferably 50%~75%, more preferably 60%~75%. According to some embodiments of the present invention, the curing conditions include: curing time ≥ 40 hours, preferably 48~72 hours. The present invention, through precise control of curing conditions, can effectively prevent alkali-activated materials from cracking due to dehydration shrinkage, thereby improving the long-term durability of cementitious materials.

[0045] According to some embodiments of the present invention, the mold is a movable, layered mold. According to some embodiments of the present invention, the height of the mold is 15-25 cm. In the present invention, the compacted thickness of the artificial seepage-proof and waterproof layer is not less than 0.6 m. During actual construction, the thickness of each alkali-activated material layer and the number of layers N can be determined according to the size of the mold. In some embodiments, the number of alkali-activated material layers N is ≥ 3. In some embodiments, the number of alkali-activated material layers N is an integer between 3 and 20. In some embodiments, the number of alkali-activated material layers N is an integer between 5 and 15.

[0046] The method for constructing an artificial seepage-proof and water-resistant layer in an open-pit mine spoil heap is applicable to the reconstruction of a water-resistant layer in an open-pit mine spoil heap or the construction of an artificial seepage-proof and water-resistant layer on the slope of an open-pit mine spoil heap.

[0047] Compared with the prior art, the present invention has the following beneficial effects: (1) The material used in the artificial seepage-proof and waterproof layer of the present invention is alkali-activated by mudstone and slag solid waste in the mining area, and the waste rock in the mining area is used as aggregate. It has the characteristics of high strength and low permeability. In particular, it maintains stable performance under dynamic load and high temperature environment, and has excellent resistance to disturbance and cracking.

[0048] (2) The construction method of artificial seepage-proof and water-proof layer of the present invention realizes the resource utilization of three kinds of solid waste in mining areas. It can make full use of the waste dump itself or the solid waste resources in the mining area, and can realize continuous construction in layers on site. The layer thickness and density are controllable and the interlayer is tightly bonded. The complete set of pumping and vibration compaction system realizes automated operation, improves construction efficiency and reduces construction cycle.

[0049] (3) The method of constructing the artificial seepage-proof and waterproof layer of the present invention is simple, safe and environmentally friendly in situ construction. All materials are non-toxic substances and do not react with water in physical and chemical reactions during long-term service. It has permanent durability and excellent ecological restoration effect. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the reconstructed waterproof layer for slope protection of an open-pit mine spoil heap according to a specific embodiment of the present invention. Detailed Implementation

[0051] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0052] Unless otherwise defined, the technical terms used in the following embodiments and comparative examples have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments and comparative examples are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments and comparative examples can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in conventional experimental operations; unless otherwise specified, the experimental methods are all conventional methods.

[0053] like Figure 1 As shown, the method for constructing an artificial seepage-proof and water-resistant layer in an open-pit mine spoil heap provided by the present invention includes the following steps: (T1) Level the construction area and then set up the formwork; (T2) Pump mudstone-slag-based alkali-activating material into the mold, compact and cure it to obtain a single-layer waterproof layer; (T3) Using the same methods as steps (T1) and (T2), multiple waterproof layers are repeatedly laid on the surface of the single-layer waterproof layer. Then, an impermeable wall is constructed on the periphery to complete the layered laying of the waterproof layer reconstruction for the slope protection of the open-pit mine spoil heap (structural diagram as shown). Figure 1 (As shown).

[0054] The mudstone powder used in the following experiments of this invention came from the Haerwusu open-pit coal mine, and its mineral composition is: quartz 22.8%, kaolinite 24.9%, orthoclase 22.3%, albite 18.1%, and muscovite 11.9%. The mudstone has a porosity of 63.4% and a density of 2.3 g / cm³. 3 The water content is 5.4%, and the swelling rate is 29.7%. The chemical composition of the mudstone obtained by fluorescence analysis is as follows (mass percentage): SiO2 61.28%, Al2O3 15.82%, Fe2O3 6.58%, K2O 5.24%, Na2O 3.64%, and other components 7.44%.

[0055] The slag powder used in the following experiments of this invention is S95 grade slag powder, and its main components are (by mass percentage): SiO2 34.61%, Al2O3 16.34%, CaO 36.72%, Fe2O3 0.96%, MgO 8.34%, K2O 0.43%, TiO2 1.96%, and other components 7.44%.

[0056] The waste stone fine aggregate used in the following experiments of this invention came from an open-pit coal mine in Xinjiang. It was sandstone without sulfides. X-ray fluorescence spectrometry (XRF) analysis determined that the aggregate mainly contained SiO2, and also contained a certain amount of Al2O3 and CaO, as well as small amounts of MgO, Fe and K2O, etc. The chemical composition is as follows (mass percentage): CaO 5.63%, SiO2 68.32%, Al2O3 16.21%, MgO 3.89%, Fe 3.59% and K2O 2.36%.

[0057] In the following experiments of this invention, the uniaxial compressive strength of the waterproof layer was measured in accordance with the "Standard for Test Methods of Engineering Rock Mass" GB / T50266.

[0058] In the following experiments of this invention, the permeability of the waterproof layer was determined using the "steady-state gas method (THMC system)". The experiments were conducted indoors at an air-conditioned temperature of 20°C, and the confining pressure of the pressure chamber was set to 2 MPa. The experimental steps are as follows: ① Seal the sample in a sealed package to prevent debris from entering the instrument; ② Check if the testing instrument is operating normally; ③ Place the sample into the instrument, close the instrument valve, and ensure the instrument is airtight; ④ Turn on the air pump and apply confining pressure to 2 MPa; ⑤ Open the software to record data, open the air valve, and wait for 30 minutes; ⑥ Save the data and release the confining pressure; ⑦ Remove the sample and seal it; ⑧ Collect and process the data.

[0059] Example 1 The specific process for reconstructing the aquitard layer of a spoil heap under high-temperature conditions (38~40℃) in an arid area of ​​an open-pit coal mine in Xinjiang is as follows: Step (1): Conduct on-site survey of the spoil heap, designing a total thickness of 3m; then level the construction area, using a vibratory roller to compact the road surface three times, controlling the flatness error to be within 2mm, and spraying atomized water at a dosage of 0.5L / m. 2 To suppress dust and ensure the stability of the base.

[0060] Step (2): Prepare the alkali-activating material, which contains 560 kg of mudstone, 840 kg of slag, 4200 kg of waste rock aggregate, 1183 kg of water glass, 291 kg of sodium hydroxide, and 1325 kg of water; the average particle size of the mudstone is 0.5 mm, and the specific surface area is 460 m². 2 / kg; the average particle size of the slag is 40μm; the average particle size of the aggregate is 1mm, and the mud content is 0.3wt%; the modulus of the activator is 1. Mudstone powder and slag powder are mixed for 3 minutes to obtain a cementitious material. Then, fine aggregate from waste rock is added to a dry mixing container for a second mixing process of 5 minutes to ensure uniform distribution of the aggregate and cementitious material. After thorough mixing, a dry mixture is obtained. Flake sodium hydroxide is added to a liquid water glass solution with a modulus of 3.3, stirred thoroughly, and allowed to cool to room temperature to obtain an activator with a final modulus of 1.0. The activator is thoroughly mixed with water to obtain a slurry. The slurry is slowly poured into the already mixed dry mixture and stirred for 120 seconds using a forced mixer to obtain an alkali-activated material.

[0061] Step (3): Construct a movable steel road construction mold on the base surface. The mold is 20cm high and fixed with bolts. The verticality error of the mold is ≤1 mm. Leave a 15 cm operating gap on the outside of the mold to facilitate the insertion of a vibratory compactor. Then, use an HBT80C concrete pump to pump alkali-activated material into the mold. Use a ZDN-50 immersion vibratory compactor (frequency 2800 times / min) to compact the layers. The vibration time for each layer is 8 minutes to ensure a density of ≥96%. Use a scraper to level the surface.

[0062] Step (4): Within 1 hour of the completion of grout pouring, cover the formed reconstructed waterproof layer with composite geotextile (400g / m²). 2 The automatic sprinkler system is activated to spray water for moisturizing and maintenance (spray volume 1.5L / m²). 2 ·h), ensuring humidity at 70%, and continuously watering for 72 hours.

[0063] Step (5): 24 hours after pouring, remove the mold and geotextile, check the surface integrity of the waterproof layer, and roughen the joints between layers (1 mm roughness) to enhance the bonding performance of the next layer. Repeat the above steps to lay a total of 15 waterproof layers. Construct a C30 reinforced concrete seepage barrier wall on the periphery, with a wall thickness of 0.5 m and a height of 1.5 m. The wall is equipped with a steel mesh with a spacing of 200 mm. The overall permeability of the structure is 1×10⁻⁶. -16 m 2 .

[0064] After 28 days of curing, the uniaxial compressive strength reached 7.76 MPa, and the permeability was controlled at 3.95 × 10⁻⁶ MPa. -16 m 2 It exhibits excellent resistance to drying shrinkage at 100℃, with no surface cracking, meeting the needs of long-term water storage and ecological reclamation.

[0065] Example 2 For the slope area of ​​the open-pit mine spoil heap, the specific process is as follows: Step (1): Conduct on-site survey of the slope area, designing a total thickness of 1m; then level the construction area, controlling the flatness error to be within 5mm, and spray atomized water at a dosage of 0.5L / m. 2 To suppress dust and ensure the stability of the base.

[0066] Step (2): Set the slope formwork to use lightweight aluminum alloy formwork (4 mm thick), and the adjustable formwork support system is laid along the slope, with a slope ratio of 1:1.5; Preparation of alkali activation material: Same as the alkali activation material in Example 2.

[0067] Add the accelerator (calcium aluminate early strength agent) according to the conventional addition amount in this field, control the initial setting time to not exceed 20 minutes, and set the construction window to close quickly.

[0068] Step (3): Construct a movable steel road construction mold on the base surface. The mold is 20cm high and fixed with bolts. The verticality error of the mold is ≤1 mm. Leave a 15 cm operating gap on the outside of the mold to facilitate the insertion of a vibratory compactor. Then, use an HBT80C concrete pump to pump the slurry into the mold. Use a ZDN-50 immersion vibratory compactor (frequency 3000 times / min) to compact the layers. The vibration time for each layer is 10 minutes to ensure a density of ≥97%. Use a scraper to level the surface.

[0069] Step (4): Within 1 hour of the completion of grout pouring, cover the formed reconstructed waterproof layer with composite geotextile (400g / m²). 2 And start the automatic sprinkler system to spray water for moisturizing and maintenance (spray volume 2L / m). 2 ·h), ensuring humidity at 75%, and continuously watering for 48 hours.

[0070] Step (5): 24 hours after pouring, remove the mold and geotextile, check the surface integrity of the waterproof layer, and roughen the joints between layers (1 mm roughness) to enhance the bonding performance of the next layer. Repeat the above steps to lay a total of 5 waterproof layers; construct a C30 reinforced concrete seepage barrier wall on the periphery, with a wall thickness of 0.4 m and a height of 1.5 m, and internal steel mesh with a spacing of 200 mm. The overall permeability of the structure is 1×10⁻⁶. -16 m 2 .

[0071] After 28 days of curing, the uniaxial compressive strength reached 7.84 MPa, and the permeability was controlled at 3.46 × 10⁻⁶ MPa. -16 m 2 It has excellent resistance to drying shrinkage at 100℃, no surface cracking, and is suitable for seepage prevention projects in slope lining and concentrated drainage areas.

[0072] Example 3 The difference from Example 1 is that in step (3), the frequency of the vibratory compactor is 2000 times / min, the single-layer vibration time is 5min, and the density is 90%.

[0073] After 28 days of curing, the uniaxial compressive strength was 6.89 MPa, and the permeability was 4.43 × 10⁻⁶. -16 m 2 .

[0074] Example 4 The difference from Example 1 is that in step (4), the humidity during curing is 50%.

[0075] After 28 days of curing, the uniaxial compressive strength was 7.24 MPa, and the permeability was 4.32 × 10⁻⁶. -16 m 2 .

[0076] Example 5 The difference from Example 1 is that in step (5), the roughness of the roughening process is 0.5 mm.

[0077] After 28 days of curing, the uniaxial compressive strength was 7.58 MPa, and the permeability was 4.51 × 10⁻⁶. -16 m 2 .

[0078] Comparative Example 1 The difference from Example 1 is that in step (2), the waste stone aggregate is replaced with the same mass fraction of "ISO standard sand", the particle size range of ISO standard sand is 0.08 mm ~ 2.0 mm.

[0079] After 28 days of curing, the uniaxial compressive strength was 8.0 MPa, and the permeability was 3.7 × 10⁻⁶. -16 m 2 .

[0080] Example 6 Based on the process of Example 1, multiple groups of alkali-activated materials were prepared according to the formulas (kg) in Table 1 below, and the effects of different alkali-activated material formulas on the performance of the waterproof layer were investigated.

[0081] Table 1

[0082] After 28 days of curing, the test results of uniaxial compressive strength and permeability are shown in Tables 2 and 3 below. To comprehensively evaluate the anti-disturbance performance and engineering adaptability of the alkali-activated material in this application under actual working conditions, multiple uniaxial loading cycles were conducted to test the compressive strength and permeability. The decrease rate of compressive strength and the increase in permeability after 100 uniaxial loading cycles were calculated to evaluate the material's anti-disturbance performance. The test method was as follows: The WDW-300 universal testing system was used, with an upper loading limit of 1 MPa and a lower unloading limit of 0 MPa, simulating the maximum ground pressure that an open-pit mining truck (MT5500B type) might generate during operation in a spoil heap. The sample loading rate was 0.5 mm / min. After 0 and 100 uniaxial loading cycles (N), the material permeability Kp was determined using the "gas steady-state method (THMC system)".

[0083] Table 2

[0084] Table 3

[0085] The rate of decrease in compressive strength = the difference between the compressive strength after 0 cycles of uniaxial loading and after 100 cycles of uniaxial loading, divided by the compressive strength after 0 cycles of uniaxial loading.

[0086] Permeability increase = the difference between the permeability after 0 cycles of uniaxial loading and after 100 cycles of uniaxial loading, divided by the permeability after 0 cycles of uniaxial loading.

[0087] The experimental results above demonstrate that this invention, through the layered construction of an artificial waterproof layer for open-pit coal mine spoil heaps, combines the excellent seepage prevention performance of mudstone-slag-based alkali-activated materials with the efficient integration of modular and automated construction equipment, achieving high-quality construction of the artificial waterproof layer. This process maintains good structural integrity and permeability stability even under repeated load disturbances and complex site conditions, effectively enhancing the water storage and vegetation restoration capabilities of the spoil heap. The materials are sourced from local mining solid waste, and the preparation process is environmentally friendly and controllable, exhibiting significant advantages such as in-situ resource utilization, low carbon emissions, high efficiency, and strong adaptability. It is suitable for seepage prevention projects in open-pit mine spoil heaps, tailings dams, and large-scale abandoned land, possessing broad engineering application and promotion value.

[0088] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. An artificial seepage-proof and water-resistant layer for an open-pit mine spoil heap, comprising N layers of alkali-activated material laid sequentially from bottom to top on a base layer of the area to be constructed; wherein, N≥2, the alkali-activated material includes cementitious material, alkali activator and waste rock aggregate; based on the total weight of the cementitious material as 100%, the cementitious material includes 20%~80% mudstone powder and 20%~80% slag powder.

2. The artificial waterproof barrier layer according to claim 1, characterized in that, Based on the total weight of the cementing material as 100%, the cementing material comprises 30% to 60% mudstone powder and 40% to 70% slag powder, preferably comprising 30% to 60% mudstone powder and 40% to 70% slag powder; and / or The weight ratio of the alkali activator to the cementitious material is 1:(1~3), preferably 1:(1~2), more preferably 1:(1~1.5); and / or The weight ratio of the waste stone aggregate to the cementitious material is (2.0 ~ 4.0): 1, preferably (2.5 ~ 3.5):

1.

3. The artificial waterproof barrier layer according to claim 1 or 2, characterized in that, The average particle size of the mudstone powder is ≤1 mm, preferably 0.1~1.0 mm; and / or The specific surface area of ​​the mudstone powder is ≥450m². 2 / kg, preferably 450~500m 2 / kg; and / or The slag powder includes slag powder of grade S75 or higher; and / or The average particle size of the slag powder is ≤45μm, preferably 30~45μm; and / or The waste rock aggregate is selected from stripped sandstone from the mining area; and / or The average particle size of the waste stone aggregate is ≤1.5mm, preferably 0.1~1.5mm.

4. The artificial waterproof barrier layer according to any one of claims 1 to 3, characterized in that, The alkaline activator comprises a mixture of sodium hydroxide and water glass; preferably, the mass ratio of sodium hydroxide to water glass in the alkaline activator is 1:(3.5~4.5); and / or The modulus of the alkali activator is 0.8 to 1.

2.

5. The artificial waterproof barrier layer according to any one of claims 1 to 4, characterized in that, The water-cement ratio of the alkali-activated material is 1:(0.5~1.5), preferably 1:(0.8~1.2); Preferably, by weight, the alkali activating material comprises: 560-2240 parts of cementitious material, 4000-5600 parts of waste stone aggregate, 1200-1800 parts of alkali activator, and 1000-1500 parts of water. Preferably, by weight, the alkali-activated material comprises: 420-840 parts mudstone powder, 560-980 parts slag powder, 4000-4400 parts waste stone fine aggregate, 1100-1200 parts water glass, 280-300 parts sodium hydroxide, and 1300-1350 parts water.

6. The artificial waterproof barrier layer according to any one of claims 1 to 5, characterized in that, It also includes a seepage barrier wall set around the N alkali-activated material layers; Preferably, the seepage barrier is a C30 reinforced concrete seepage barrier; Preferably, the height of the seepage barrier is 1.4~1.6m, more preferably 1.45~1.55m; Preferably, the thickness of the seepage barrier is 0.4~0.6m, more preferably 0.45~0.55m; Preferably, the seepage barrier wall is provided with a steel mesh, and the spacing of the steel mesh is preferably ≤200mm, more preferably 100~200mm; Preferably, the permeability of the impermeable wall is ≤1×10⁻⁶. -16 m 2 More preferably 0.5×10 -16 ~1×10 -16 m 2 .

7. The method for constructing an artificial seepage-proof and water-resistant layer in an open-pit mine spoil heap as described in any one of claims 1-6, comprising the following steps: (1) The area to be constructed is vibrated and / or leveled to obtain the base layer; (2) N layers of alkali-activated material are laid sequentially from bottom to top on the base layer to obtain an artificial waterproof layer; wherein, N≥2, the alkali-activated material includes cementitious material, alkali activator and waste rock aggregate; based on the total weight of the cementitious material as 100%, the cementitious material includes 20%~80% mudstone powder and 20%~80% slag powder.

8. The construction method according to claim 7, characterized in that, Step (2) includes: (S1) A mold is erected on the base layer, the alkali activating material is injected into the mold, and after vibration compaction and curing, the first alkali activating material layer is obtained; (S2) After the N-1th alkali-activated material layer is compacted and / or leveled, a mold is set up, the alkali-activated material is injected into the mold, and after compaction and curing, the Nth alkali-activated material layer is obtained. (S3) Construct the seepage barrier wall around the N alkali-activated material layers; Preferably, the mold is a movable, layered mold; preferably, the height of the mold is 15~25cm; Preferably, steps (S1) and (S2) further include: after curing, roughening the surface of the alkali-activated material layer; More preferably, the roughness of the roughening treatment is ≥0.5mm, and even more preferably 1~2mm.

9. The construction method according to claim 7 or 8, characterized in that, The conditions for the vibration compaction treatment include: a vibration frequency of 2000-3000 times / minute, preferably 2500-3000 times / minute; and / or, a single-layer vibration time of ≥5 minutes, preferably 5-15 minutes; and / or, a compaction degree of ≥90%, preferably ≥96%; and / or The flatness error of the leveling process is -5~5mm.

10. The construction method according to claim 8 or 9, characterized in that, The conditions for maintenance include: humidity ≥ 50%, preferably 50%~75%, more preferably 60%~75%; and / or, maintenance time ≥ 40 hours, preferably 48~72 hours.

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