An anti-seepage material based on aeolian silt and a preparation method thereof
By combining aeolian silt, gneiss gravel, and modified bentonite, high-strength seepage-proof materials were prepared, solving the problem of insufficient mechanical strength of aeolian silt and improving the seepage-proof performance and stability of the core-wall rockfill dam.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SINOHYDRO BUREAU 5
- Filing Date
- 2023-05-19
- Publication Date
- 2026-06-12
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of water conservancy and hydropower engineering, specifically to a seepage-proof material based on aeolian silt and its preparation method. Background Technology
[0002] The core wall, as a crucial component of the seepage control structure of a core-wall rockfill dam, directly impacts the overall construction quality of the dam and its safe operation after impoundment. The core wall's seepage-proof soil is a key material in core-wall rockfill dams, playing a controlling role in dam seepage and stability. Cracks in the seepage-proof body and the resulting seepage erosion are significant factors affecting dam safety; therefore, the requirements for the seepage-proof soil are very high. Due to the complex geological structure of the reservoir area and the extremely deep riverbed overburden, the technical challenges are significant. In addition to meeting seepage control requirements, the soil used in core-wall rockfill dams must also possess good physical and mechanical properties to coordinate with the deformation of the dam shell rockfill, reduce the arching effect of the dam shell on the core wall, improve the stress-strain balance of the core wall, and reduce the probability of core wall cracks.
[0003] Soil formed by wind deposition is mainly composed of silt, has a large yield, and a low clay content. It has advantages such as pure soil and low permeability coefficient. Overall, it belongs to non-dispersed to transitional soil, but its mechanical strength is relatively low and it cannot be directly used as an impermeable soil material. Summary of the Invention
[0004] The purpose of this invention is to provide an impermeable material based on aeolian silt and its preparation method, which solves the problem that aeolian soil is difficult to use directly as an impermeable material.
[0005] This invention is achieved through the following technical solution:
[0006] This invention provides a seepage-proof material based on aeolian silt, which mainly comprises the following raw materials in parts by weight: 48 to 54 parts aeolian silt, 40 to 45 parts gneiss crushed stone, and 6 to 10 parts modified bentonite.
[0007] Furthermore, in a preferred embodiment of the present invention, the seepage-proof material based on aeolian silt mainly comprises the following raw materials in parts by weight: 50 to 52 parts aeolian silt, 42 to 44 parts gneiss crushed stone, and 7 to 8 parts modified bentonite.
[0008] Furthermore, in a preferred embodiment of the present invention, the seepage-proof material based on aeolian silt is characterized by mainly comprising the following raw materials in parts by weight: 51 parts aeolian silt, 43 parts gneiss crushed stone, and 7.5 parts modified bentonite.
[0009] Furthermore, in a preferred embodiment of the present invention, in the aeolian silt: the content of particles smaller than 5 mm is 99% to 100%; the content of particles smaller than 0.075 mm is 85% to 99%; and the content of particles smaller than 0.005 mm is 2% to 18%.
[0010] The moisture content of the aeolian silt is 8.5% to 10%.
[0011] Furthermore, in a preferred embodiment of the present invention, the preparation of the modified bentonite includes:
[0012] Sodium-based bentonite with a clay content of 55% to 70% was mixed with water to prepare a suspension with a concentration of 1 g / mL to 1.5 g / mL. The suspension was heated to 30°C to 35°C. While stirring, sulfuric acid solution with a concentration of 0.5 mol / L to 1 mol / L was added dropwise to the suspension at a solid-liquid ratio of 1:(3 to 6). The mixture was stirred to obtain an activated solution.
[0013] While stirring, add polydimethylsiloxane with a concentration of 0.5mol / L to 1.5mol / L dropwise to the activation solution at a solid-liquid ratio of 1:(5~8), then add 0.1wt% to 0.2wt% magnesium ammonium phosphate and stir until homogeneous to obtain the modified solution.
[0014] After filtering, drying, and pulverizing the modified liquid, 20 wt% microcrystalline cellulose is added and mixed to obtain the modified bentonite.
[0015] Furthermore, in a preferred embodiment of the present invention, the gneiss crushed stone is in a saturated surface-dry state, and the particle size of the gneiss crushed stone is 50mm to 100mm.
[0016] Furthermore, in a preferred embodiment of the present invention, in the impermeable material: the content of particles smaller than 5 mm is 30% to 50%; the content of particles smaller than 0.075 mm is 35% to 55%; and the content of particles smaller than 0.005 mm is 8% to 22%.
[0017] The moisture content of the impermeable material is 12-14%.
[0018] This invention provides a method for preparing the above-mentioned seepage-proof material based on aeolian silt, comprising:
[0019] Gneiss crushed stone and modified bentonite are mixed and stirred evenly to obtain the first mixture;
[0020] The first mixture and aeolian silt are mixed and stirred evenly to obtain the impermeable material.
[0021] Furthermore, in a preferred embodiment of the present invention, the stirring conditions for obtaining the second mixture are: rotation speed 15-25 r / min, time 1-3 min.
[0022] Furthermore, in a preferred embodiment of the present invention, the stirring conditions for obtaining the impermeable material are: rotation speed 10-20 r / min, time 10-15 min.
[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0024] The seepage-proof material based on aeolian silt in this invention uses gneiss crushed stone as a gravel admixture, forming the supporting skeleton of the seepage-proof material. The high particle strength increases shear strength and deformation modulus, reducing shrinkage. Modified bentonite is used, which has stronger adsorption and bonding properties, thereby improving the seepage-proof performance of the material. The seepage-proof material based on aeolian silt of this invention exhibits excellent seepage-proof performance and high mechanical strength. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0026] The technical solution of this invention is as follows:
[0027] A seepage-proof material based on aeolian silt mainly comprises the following raw materials in parts by weight: 48 to 54 parts aeolian silt, 40 to 45 parts gneiss crushed stone, and 6 to 10 parts modified bentonite.
[0028] The preparation of modified bentonite includes:
[0029] Sodium-based bentonite with a clay content of 55% to 70% was mixed with water to prepare a suspension with a concentration of 1 g / mL to 1.5 g / mL. The suspension was heated to 30°C to 35°C. While stirring, sulfuric acid solution with a concentration of 0.5 mol / L to 1 mol / L was added dropwise to the suspension at a solid-liquid ratio of 1:(3 to 6). The mixture was stirred to obtain an activated solution.
[0030] While stirring, add polydimethylsiloxane with a concentration of 0.5mol / L to 1.5mol / L dropwise to the activation solution at a solid-liquid ratio of 1:(5~8), then add 0.1wt% to 0.2wt% magnesium ammonium phosphate and stir until homogeneous to obtain the modified solution.
[0031] After filtering, drying, and pulverizing the modified liquid, 20 wt% microcrystalline cellulose is added and mixed to obtain the modified bentonite.
[0032] The aeolian silt contains: 99%–100% particles smaller than 5 mm; 85%–99% particles smaller than 0.075 mm; and 2%–18% particles smaller than 0.005 mm. The moisture content of the aeolian silt is 8.5%–10%. This aeolian silt has a high silt content, low clay content, and a moisture content that meets the required range.
[0033] The gneiss crushed stone is in a saturated surface-dry state, and its particle size is 50mm to 100mm. As a gravel component in the seepage-proof material, the gneiss crushed stone forms the supporting framework of the material. Its high particle strength increases shear strength and deformation modulus, while reducing shrinkage. The gneiss crushed stone has low activity and, after compaction, maintains high compaction density and shear strength, as well as low compressibility.
[0034] Bentonite, as a thickening component in impermeable materials, is inexpensive, stable, non-toxic, harmless, and has strong binding properties. It also possesses excellent hygroscopic swelling properties, high adsorption capacity, low permeability, and good self-sealing properties. This invention modifies bentonite by first acidifying it with sulfuric acid to remove impurities distributed in its channels, such as mixed organic matter, thus unblocking the pores and facilitating the diffusion of adsorbate molecules. Through the small volume of H... + Ion replacement of K between bentonite layers + Na + Ca 2+ Mg 2+ The addition of ions increases the pore volume and weakens the interlayer bonds, causing the layered lattice to break and the pores to become unblocked, thus improving adsorption performance. Furthermore, the addition of polydimethylsiloxane improves the dispersibility of bentonite, and the addition of magnesium ammonium phosphate increases the interlayer spacing of bentonite, making it easier to disperse into thinner single crystal wafers. This increases the internal surface area of the bentonite, enhancing its adsorption and bonding properties, thereby improving the impermeability of the waterproofing material. Microcrystalline cellulose, with its ester functional groups and ether bonds, can serve as a connecting framework for silt, bentonite, and crushed stone, ensuring tight bonding. Moreover, microcrystalline cellulose can intertwine with long straight chains to form a strong spatial network structure, further improving the mechanical strength of the waterproofing material.
[0035] In the impermeable material: the content of particles smaller than 5 mm is 30% to 50%; the content of particles smaller than 0.075 mm is 35% to 55%; the content of particles smaller than 0.005 mm is 8% to 22%; and the moisture content of the impermeable material is 12% to 14%.
[0036] The method for preparing an impermeable material based on aeolian silt according to an embodiment of the present invention includes:
[0037] (1) Mix gneiss crushed stone and modified bentonite at a speed of 15-25 r / min for 1-3 min to obtain the first mixture;
[0038] (2) Mix the first mixture with the aeolian silt at a speed of 10-20 r / min for 10-15 min until the mixture is homogeneous and the impermeable material is obtained.
[0039] The following are specific embodiments.
[0040] It should be noted that, in the following embodiments, the content of particles smaller than 5 mm is 99% to 100% (average 99.5%); the content of particles smaller than 0.075 mm is 85% to 99% (average 95%); and the content of particles smaller than 0.005 mm is 2% to 18% (average 10%).
[0041] The moisture content of the aeolian silt is 8.5% to 10% (average 9%).
[0042] The gneiss crushed stone is in a saturated surface-dry state, and the particle size of the gneiss crushed stone is 50mm to 100mm (average 75mm).
[0043] Example 1:
[0044] The seepage-proof material based on aeolian silt in this embodiment mainly includes the following raw materials in parts by weight: 48 parts aeolian silt, 40 parts gneiss crushed stone and 6 parts modified bentonite.
[0045] The preparation of modified bentonite includes:
[0046] Sodium-based bentonite with a clay content of 55%–70% (average 65%) was mixed with water to prepare a suspension with a concentration of 1 g / mL. The suspension was heated to 30°C, and while stirring, a sulfuric acid solution with a concentration of 0.5 mol / L was added dropwise to the suspension at a solid-liquid ratio of 1:3. The mixture was stirred to obtain an activated solution.
[0047] While stirring, 0.5 mol / L polydimethylsiloxane was added dropwise to the activation solution at a solid-liquid ratio of 1:5, followed by the addition of 0.1 wt% magnesium ammonium phosphate and stirring until homogeneous to obtain the modified solution.
[0048] After filtering, drying, and pulverizing the modified liquid, 20 wt% microcrystalline cellulose is added and mixed to obtain the modified bentonite.
[0049] The method for preparing the seepage-proof material based on aeolian silt in this embodiment includes:
[0050] (1) Mix gneiss crushed stone and modified bentonite at a speed of 15 r / min for 1 min to obtain the first mixture;
[0051] (2) Mix the first mixture with the aeolian silt at a speed of 10 r / min for 10 min, and stir until uniform to obtain the impermeable material.
[0052] Example 2:
[0053] The seepage-proof material based on aeolian silt in this embodiment mainly includes the following raw materials in parts by weight: 50 parts aeolian silt, 42 parts gneiss crushed stone and 7 parts modified bentonite.
[0054] The preparation of modified bentonite includes:
[0055] Sodium-based bentonite with a clay content of 55%–70% (average 65%) was mixed with water to prepare a suspension with a concentration of 1.0 g / mL. The suspension was heated to 32°C, and while stirring, a sulfuric acid solution with a concentration of 0.75 mol / L was added dropwise to the suspension at a solid-liquid ratio of 1:4.5. The mixture was stirred to obtain an activated solution.
[0056] While stirring, 1 mol / L polydimethylsiloxane was added dropwise to the activation solution at a solid-liquid ratio of 1:6, followed by the addition of 0.15 wt% magnesium ammonium phosphate and stirring until homogeneous to obtain the modified solution.
[0057] After filtering, drying, and pulverizing the modified liquid, 20 wt% microcrystalline cellulose is added and mixed to obtain the modified bentonite.
[0058] The method for preparing the seepage-proof material based on aeolian silt in this embodiment includes:
[0059] (1) Mix gneiss crushed stone and modified bentonite at a speed of 20 r / min for 2 min to obtain the first mixture;
[0060] (2) Mix the first mixture with the aeolian silt at a speed of 15 r / min for 12 min to obtain the impermeable material.
[0061] Example 3:
[0062] The seepage-proof material based on aeolian silt in the embodiment mainly includes the following raw materials in parts by weight: 51 parts aeolian silt, 43 parts gneiss crushed stone and 7.5 parts modified bentonite.
[0063] The preparation of modified bentonite includes:
[0064] Sodium-based bentonite with a clay content of 55%–70% (average 65%) was mixed with water to prepare a suspension with a concentration of 1.5 g / mL. The suspension was heated to 35°C, and while stirring, a sulfuric acid solution with a concentration of 1 mol / L was added dropwise to the suspension at a solid-liquid ratio of 1:6. The mixture was stirred to obtain an activated solution.
[0065] While stirring, 1.5 mol / L polydimethylsiloxane was added dropwise to the activation solution at a solid-liquid ratio of 1:8, followed by the addition of 0.2 wt% magnesium ammonium phosphate and stirring until homogeneous to obtain the modified solution.
[0066] After filtering, drying, and pulverizing the modified liquid, 20 wt% microcrystalline cellulose is added and mixed to obtain the modified bentonite.
[0067] The method for preparing the seepage-proof material based on aeolian silt in this embodiment includes:
[0068] (1) Mix gneiss crushed stone and modified bentonite at a speed of 25 r / min for 3 min to obtain the first mixture;
[0069] (2) Mix the first mixture with the aeolian silt at a speed of 20 r / min for 15 min, and stir until uniform to obtain the impermeable material.
[0070] Example 4:
[0071] The seepage-proof material based on aeolian silt in this embodiment mainly includes the following raw materials in parts by weight: 52 parts aeolian silt, 44 parts gneiss crushed stone and 8 parts modified bentonite.
[0072] The preparation method of the seepage-proof material based on aeolian silt and the preparation method of the modified bentonite in this embodiment are the same as those in Example 1.
[0073] Example 5:
[0074] The seepage-proof material based on aeolian silt in this embodiment mainly includes the following raw materials in parts by weight: 54 parts aeolian silt, 45 parts gneiss crushed stone and 10 parts modified bentonite.
[0075] The preparation method of the seepage-proof material based on aeolian silt and the preparation method of the modified bentonite in this embodiment are the same as those in Example 2.
[0076] Compare with Example 1:
[0077] The composition and preparation method of the seepage-proof material based on aeolian silt in this comparative example are the same as those in Example 1, except that unmodified bentonite is used.
[0078] 1. Density test
[0079] The density of the seepage-proof materials based on aeolian silt prepared in Examples 1-5 and Comparative Example 1 was tested. The test methods were carried out in accordance with the provisions of "Specifications for Geotechnical Testing of Hydropower and Water Conservancy Projects" DL / T5355-2006 and "Specifications for Compaction Testing of Earth-Rock Dam Materials" NB / T35016-2013: The test pit water filling method was adopted. The soil with a deep layer of vibratory roller teeth at the test point location was excavated. A 50cm diameter ring was used. The outer edge of the ring was not less than 0.5m from the edge of the test unit and not less than 1m from the end line. The center distance between two adjacent test pits was not less than twice the diameter of the largest test pit. The excavation depth was equal to the thickness of the fill layer. Five sampling test pits were arranged for each combination. The average value of the test results of the five test pits was used as the compacted dry density and moisture content of the test unit.
[0080] 2. Permeability test
[0081] After the density test, an in-situ permeability test was conducted. The test location was staggered from the density test point. A permeability device (inner ring diameter 22.6cm, height 15cm; outer ring inner diameter 45.2cm, height 15cm) was used. A test pit of 1.5m × 2.0m was excavated at the predetermined depth in the test area. A water storage pit with a diameter equal to that of the outer ring (45.2cm) and a depth of 15cm to 20cm was excavated at the bottom of the pit. The bottom of the pit was leveled, and a 20mm thick impermeable material with a particle size of 10mm to 20mm was evenly laid on the bottom of the two rings. Then, water was injected to conduct the in-situ permeability test.
[0082] 3. Compression test:
[0083] High-pressure large-scale compression tests (saturated and unsaturated tests) were conducted on the seepage-proof materials based on aeolian silt prepared in Examples 1-5 and Comparative Example 1, with pressures ranging from 0.1 to 0.2 MPa.
[0084] The results of the above experiments are shown in Table 1.
[0085] Table 1
[0086]
[0087] As can be seen from the results in the table above, the moisture content of the seepage-proof material can be adjusted during the preparation process to meet the requirements. However, the dry density, permeability coefficient, and compression coefficient show that the seepage-proof material of the present invention performs better, has a better seepage-proof effect, and better mechanical properties.
[0088] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A seepage-proof material based on aeolian silt, characterized in that, The raw materials include the following parts by weight: 48 to 54 parts of aeolian silt, 40 to 45 parts of gneiss crushed stone, and 6 to 10 parts of modified bentonite; In the aforementioned aeolian silt: the content of particles smaller than 5 mm is 99%~100%; the content of particles smaller than 0.075 mm is 85%~99%; and the content of particles smaller than 0.005 mm is 2%~18%. The moisture content of the aeolian silt is 8.5%~10%; The preparation of the modified bentonite includes: Sodium-based bentonite with a clay content of 55%~70% was mixed with water to prepare a suspension with a concentration of 1g / mL~1.5g / mL. The suspension was heated to 30℃~35℃, and while stirring, sulfuric acid solution with a concentration of 0.5mol / L~1mol / L was added dropwise to the suspension at a solid-liquid ratio of 1:(3~6). The mixture was stirred to obtain an activated solution. While stirring, add polydimethylsiloxane with a concentration of 0.5mol / L to 1.5mol / L dropwise to the activation solution at a solid-liquid ratio of 1:(5~8), then add 0.1 wt% to 0.2 wt% magnesium ammonium phosphate and stir until homogeneous to obtain the modified solution; After filtering, drying, and pulverizing the modified liquid, 20 wt% microcrystalline cellulose was added and mixed to obtain the modified bentonite.
2. The seepage-proof material based on aeolian silt according to claim 1, characterized in that, The raw materials include the following parts by weight: 50 to 52 parts of aeolian silt, 42 to 44 parts of gneiss crushed stone, and 7 to 8 parts of modified bentonite.
3. The seepage-proof material based on aeolian silt according to claim 2, characterized in that, The raw materials include the following parts by weight: 51 parts aeolian silt, 43 parts gneiss gravel, and 7.5 parts modified bentonite.
4. The seepage-proof material based on aeolian silt according to any one of claims 1-3, characterized in that, The gneiss crushed stone is in a saturated surface-dry state, and the particle size of the gneiss crushed stone is 50mm~100mm.
5. The seepage-proof material based on aeolian silt according to any one of claims 1-3, characterized in that, In the aforementioned impermeable material: the content of particles smaller than 5mm is 30%~50%; the content of particles smaller than 0.075mm is 35%~55%; and the content of particles smaller than 0.005mm is 8%~22%. The moisture content of the impermeable material is 12-14%.
6. A method for preparing an impermeable material based on aeolian silt according to any one of claims 1-5, characterized in that, include: Gneiss crushed stone and modified bentonite are mixed and stirred evenly to obtain the first mixture; The first mixture and aeolian silt are mixed and stirred evenly to obtain the impermeable material.
7. The method for preparing the impermeable material based on aeolian silt according to claim 6, characterized in that, The stirring conditions for obtaining the first mixture are: rotation speed 15~25 r / min, time 1~3 min.
8. The method for preparing the impermeable material based on aeolian silt according to claim 6, characterized in that, The stirring conditions for obtaining the impermeable material are: rotation speed 10~20 r / min, time 10~15 min.