A microbial-magnesium oxide gradient anti-seepage reinforcement system for earth embankment and channel and a construction method thereof

Abstract

The application discloses a kind of microbial-magnesium oxide gradient seepage prevention and reinforcement systems for soil embankment, channel and construction method, it is related to water conservancy engineering seepage prevention and reinforcement technical field.The surface dense seepage prevention layer, intermediate transition reinforcement layer and deep stable layer are sequentially arranged along the direction of soil embankment or channel water side to backwater side;The surface dense seepage prevention layer is formed by shallow high-pressure jet grouting into continuous wall or panel wall structure using high-concentration bacteria solution and high-activity magnesium oxide slurry;The intermediate transition reinforcement layer is constructed by grouting using medium-concentration bacteria solution and high-activity magnesium oxide slurry;Deep stable layer is constructed by point grouting at preset intervals using low-concentration bacteria solution and high-activity magnesium oxide slurry.The present application uses microbial mineralization to intelligently fill micro-pores and cracks, forms a self-adapting seepage prevention body, and the three-layer structure realizes seepage prevention, transition and stability functions respectively, cooperatively improves soil permeability resistance and strength from surface to deep layer, and adapts to complex soil environment.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering seepage prevention and reinforcement technology, and in particular to a microbial-magnesium oxide gradient seepage prevention and reinforcement system and construction method for earthen dams and canals. Background Technology

[0002] Earthen embankments and canals are core facilities in water conservancy projects, and their seepage prevention performance directly determines the safety of the project and the efficiency of water resource utilization. Existing seepage prevention technologies mainly include clay lining, concrete lining, geomembrane laying, and cement grouting, but they generally have significant defects: they are easily affected by soil deformation and will crack and age; they have poor compatibility with the soil, leading to interface delamination; they have weak adaptability to deformation; their seepage prevention function is prone to failure after long-term use; and some materials are not environmentally friendly enough.

[0003] Conventional single-microorganism-induced calcium carbonate precipitation seepage control systems suffer from problems such as difficulty in controlling the reaction rate and poor uniformity of the seepage control layer, failing to achieve deep penetration reinforcement and the construction of gradient seepage control structures, and exhibiting poor synergistic improvement in seepage control durability and soil structural strength. On the other hand, single-active magnesium oxide hydration cementitious seepage control systems without the addition of microorganisms have low early strength, a high risk of shrinkage cracking, weak bonding with soil particles, and hydration reaction rates and seepage control effects that fail to meet construction requirements. Furthermore, existing construction techniques are mostly limited to surface treatment, unable to form a gradient seepage control structure from the surface to the depths, making it difficult to address leakage problems in complex soils.

[0004] Therefore, there is an urgent need to develop a new seepage prevention and reinforcement technology that combines adaptive seepage prevention, high durability, ecological compatibility, and gradient reinforcement functions to address the shortcomings of existing technologies. Summary of the Invention

[0005] The main objective of this invention is to provide a microbial-magnesium oxide gradient anti-seepage reinforcement system and construction method for earthen embankments and channels, in order to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides a microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels, comprising a surface dense seepage prevention layer, an intermediate transition reinforcement layer and a deep stabilization layer arranged sequentially along the direction from the water-facing side to the back water-facing side of the earthen embankment or channel; The dense impermeable surface layer is formed by shallow high-pressure jet spraying of a high-concentration bacterial solution with OD600=1.2-2.0, urea with 0.8-1.5mol / L and a high-activity magnesium oxide slurry with MgO content of 3-8wt% to form a continuous wall or panel wall structure with a permeability coefficient ≤10-7cm / s. The intermediate transition reinforcement layer is constructed by grouting with a medium concentration of bacterial solution with OD600=0.9-1.2, 0.8-1.5mol / L urea, and the above-mentioned highly active magnesium oxide slurry. The deep stabilizing layer is constructed by point injection of a low-concentration bacterial solution with OD600=0.6-0.9, urea with 0.8-1.5mol / L, and the above-mentioned highly active magnesium oxide slurry at a preset interval.

[0007] Furthermore, the bacterial species in the high-concentration bacterial solution are at least one of Bacillus pasteurellii and Diplococcus pasteurellii.

[0008] Furthermore, the surface dense impermeable layer, the intermediate transition reinforcement layer, and the deep stabilizing layer are located sequentially within a depth range of 30cm from the water-facing side, 30-100cm from the water-facing side, and 100-200cm from the water-facing side.

[0009] This invention also provides a construction method for a microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels, characterized in that, to form a microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in any one of claims 1-3, the method includes the following steps: S1. Preliminary preparation: Investigate the soil of the embankment / channel, and detect and mark weak seepage channels through water injection tests; S2. Construction of the dense surface impermeable layer: Within 30cm from the water-facing side, a shallow high-pressure jet grouting process is adopted, and the construction is carried out in a "bacterial solution-cementing solution-curing" cycle mode. The grouting pressure is controlled at 0.6-1.0MPa and the grouting rate is 10-15L / min. First, a high-concentration bacterial solution with OD600=1.2-2.0 and 0.8-1.5mol / L urea are injected. After an interval of 10-30min, a high-activity magnesium oxide slurry with MgO content of 3-8wt% is injected. Curing is carried out for 1-2 days, and the cycle is repeated 3-5 times. S3. Construction of intermediate transition reinforcement layer: Within a range of 30-100cm from the water-facing side, use the same grouting pressure and rate as the surface layer to inject medium-concentration bacterial solution with OD600=0.9-1.2, urea with 0.8-1.5mol / L and high-activity magnesium oxide slurry, and cure for 2-4 days, and cycle 2-3 times. S4. Construction of deep stabilization layer: Within a range of 100-200cm from the water-facing side, grouting holes are arranged in a grid pattern with a horizontal spacing of 50-100cm. Low-pressure grouting of 0.2-0.4MPa is used to inject low-concentration bacterial solution with OD600=0.6-0.9, urea of ​​0.8-1.5mol / L and highly active magnesium oxide slurry. Curing is carried out for 4-7 days and 1-2 cycles are performed. S5. Overall maintenance: The three-layer structure is uniformly maintained for 3-7 days, and the maintenance water is recycled.

[0010] Furthermore, grouting follows the order of first the outer perimeter and then the center. After completion, the grouting pipe is pulled out, and the grouting hole is sealed with the original soil or cement mortar.

[0011] Furthermore, the high-concentration bacterial solution contains at least one of Bacillus pasteurellii and Diplococcus pasteurellii, and is used in conjunction with a nutrient agent that has minimal impact on the aquatic environment.

[0012] Furthermore, in step S4, grouting holes are arranged in a grid pattern with a plane spacing of 50-100cm, with a hole diameter of 20-50mm. Low-pressure grouting of 0.2-0.4MPa is used, and the grout injection volume per hole is 0.8-1.5L / m³ soil.

[0013] The present invention has the following beneficial effects: 1. This invention utilizes microbial mineralization to intelligently fill micropores and cracks, forming an adaptive impermeable body that can address the risk of leakage caused by soil deformation.

[0014] 2. Magnesium carbonate is chemically stable in neutral to slightly alkaline aquatic environments. Compared with traditional cement-based materials, it has stronger anti-aging and anti-corrosion capabilities, thus extending the service life of engineering projects.

[0015] 3. This invention can effectively reinforce the joint between dams and rigid structures such as concrete culverts and gates, solve the problem of contact leakage, and improve the overall structural stability.

[0016] 4. This invention uses low-environmental-impact microbial strains and nutrients, recycles maintenance water, and discharges no pollutants, meeting the requirements of green engineering.

[0017] 5. This invention employs a three-layer structure to achieve seepage prevention, transition, and stabilization functions respectively, synergistically improving the soil's impermeability and strength from the surface to the deep layers, and adapting to complex soil environments. Detailed Implementation

[0018] To achieve the above objectives and effects, the technical means and structure adopted by the present invention will be described in detail with reference to the preferred embodiments of the present invention.

[0019] This invention provides a microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels, comprising a surface dense seepage prevention layer, an intermediate transition reinforcement layer and a deep stabilization layer arranged sequentially along the direction from the water-facing side to the back water-facing side of the earthen embankment or channel; The dense surface impermeable layer uses a high-concentration bacterial solution with OD600=1.2-2.0 and urea with 0.8-1.5mol / L and a highly active magnesium oxide slurry with MgO content of 3-8wt% to form a continuous wall or panel wall structure through shallow high-pressure jet spraying. By maximizing the generation of magnesium carbonate mineralization products to fill all the pores of the soil, the permeability coefficient of this layer is ≤10-7cm / s. The intermediate transition reinforcement layer is constructed by grouting a medium-concentration bacterial solution with an OD600 of 0.9-1.2 and urea with a concentration of 0.8-1.5 mol / L with the above-mentioned highly active magnesium oxide grout, which improves the overall strength and impermeability of the soil and prevents seepage deformation. The deep stabilization layer is constructed by point injection of low-concentration bacterial solution with OD600=0.6-0.9 and urea with 0.8-1.5mol / L and the above-mentioned highly active magnesium oxide slurry at preset intervals, which improves the shear strength of the soil and ensures the overall stability.

[0020] Choose bacterial strains and nutrients that have minimal impact on the aquatic environment. Bacterial strains can be at least one of *Bacillus pasteurellii* or *Diplococcus pasteurellii*. The surface dense impermeable layer, the intermediate transitional reinforcement layer, and the deep stabilizing layer are located sequentially at depths of 30cm (up to the water-facing side), 30-100cm (up to the water-facing side), and 100-200cm (up to the water-facing side).

[0021] The following detailed description is based on specific embodiments.

[0022] Example 1: Seepage Prevention and Reinforcement Project of an Earth Embankment

[0023] Project Overview: The soil of this dam is silty clay, which poses risks of surface seepage and deep local instability.

[0024] Preliminary preparations: The soil on the water-facing side of the dam was surveyed, and three weak seepage channels were detected and marked through water injection tests. Surface debris was also removed.

[0025] Construction of dense impermeable surface layer: The shallow high-pressure jet grouting process is adopted, and grouting holes are arranged within a range of 30cm from the water-facing side, with a hole spacing of 50cm. Inject high-concentration bacterial solution (Bacillus pasteurellii, OD) 600 =1.5) and 1.0 mol / L urea, grouting pressure 0.8 MPa, rate 12 L / min; After a 20-minute interval, inject highly active magnesium oxide slurry (MgO content 5wt%), with the same parameters as above; After 1.5 days of curing, the cycle is repeated 4 times to form a continuous and dense impermeable layer. The multi-cycle injection mode of "bacterial solution-cementing solution-curing" is adopted to accumulate the cementing amount with each injection, maximizing the generation of magnesium carbonate mineralization products to fill all the pores of the soil. This avoids injecting a large amount of bacterial solution and cementing solution at one time, which would cause the liquid to undergo a mineralization reaction at the channel entrance, and the generated magnesium carbonate mineralization products would block the effective permeability channel, resulting in insufficient internal reinforcement and affecting the seepage prevention and reinforcement effect.

[0026] Construction of intermediate transition reinforcement layer: Grouting holes are arranged within a range of 30-100cm from the water-facing side, with a hole spacing of 60cm. Inject a medium concentration of bacterial solution (Bacillus pasteurellii, OD) 600 =1.0), 1.0 mol / L urea and magnesium oxide slurry with the same parameters, grouting pressure 0.8 MPa, rate 12 L / min; After 3 days of curing and repeated twice, the soil compressive strength was found to be 35% higher than that of the original soil.

[0027] Construction of deep stabilization layer: Within a range of 100-200cm from the water-facing side, grouting holes are arranged in a grid pattern with a plane spacing of 80cm, and the hole diameter is 30mm. Inject low-concentration bacterial solution (Bacillus pasteurellii, OD) 600 =0.7), 1.0 mol / L urea and magnesium oxide grout, grouting pressure 0.3 MPa, single hole injection volume 1.2 L / m³ soil; Follow the grouting sequence from the outer perimeter to the center, cure for 5 days, and repeat the cycle once. After grouting is completed, the grouting pipe is pulled out and the grouting hole is sealed with the original soil.

[0028] Overall maintenance: The three-layer structure will be uniformly maintained for 5 days, and the water used for maintenance will be treated by recycling engineering wastewater.

[0029] Project results: The surface permeability coefficient of the reinforced dam is ≤10. -7 cm / s, the shear strength of deep soil is increased by 40%, there is no leakage at the joint with the dam culvert, and the design requirements are met.

[0030] Example 2: Seepage Prevention and Reinforcement Project of a Soil Irrigation Canal

[0031] Project Overview: The channel has a trapezoidal cross-section, and the soil is sandy clay. There are issues with seepage along the channel and slope stability.

[0032] Construction process: Refer to the construction steps in Example 1, and adjust the parameters as follows: Dense impermeable surface layer: bacterial solution OD 600 =1.8 (Pasteurella multocida), urea concentration 1.2mol / L, magnesium oxide slurry MgO content 6wt%, 5 cycles, curing once a day; Intermediate transition reinforcement layer: bacterial solution OD 600 =1.1, urea concentration 1.2mol / L, cycle 3 times, maintenance every 2 days; Deep stabilizing layer: bacterial solution OD 600 =0.8, urea concentration 1.2mol / L, grouting hole spacing 70cm, hole diameter 40mm, grouting pressure 0.35MPa, single hole injection volume 1.0L / m³ soil, 2 cycles, curing every 6 days.

[0033] Project results: After reinforcement, the leakage of the channel was reduced by 90%, the stability of the slope was significantly improved, and after one year of operation, there were no cracks or leaks, and there was no adverse impact on the ecological environment.

[0034] The above description is only a preferred embodiment of the present invention and not all embodiments. Anyone should know that structural changes made under the guidance of the present invention, and any technical solutions that are the same as or similar to the present invention, are within the protection scope of the present invention.

Claims

1. A microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and canals, characterized in that, It includes a surface dense impermeable layer, an intermediate transitional reinforcement layer and a deep stabilizing layer, which are sequentially installed along the water-facing side to the back side of the earthen embankment or channel; The dense impermeable surface layer adopts OD 600 A high-concentration bacterial solution (1.2-2.0 mol / L), urea (0.8-1.5 mol / L), and highly active magnesium oxide slurry (3-8 wt% MgO) are mixed and sprayed through shallow high-pressure jet grouting to form a continuous wall or panel wall structure with a permeability coefficient ≤10. - 7 cm / s; The intermediate transition reinforcement layer adopts OD. 600 It is constructed by grouting a medium concentration bacterial solution of 0.9-1.2, urea of ​​0.8-1.5 mol / L, and the above-mentioned highly active magnesium oxide slurry. The deep stabilizing layer adopts OD 600 The process involves injecting a low-concentration bacterial solution (0.6-0.9 mol / L), urea (0.8-1.5 mol / L), and the aforementioned highly active magnesium oxide slurry at predetermined intervals in a point-by-point manner.

2. The microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in claim 1, characterized in that, The high-concentration bacterial solution contains at least one of Bacillus pasteurellii and Diplococcus pasteurellii.

3. A microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in claim 1 or 2, characterized in that, The surface dense impermeable layer, the intermediate transition reinforcement layer, and the deep stabilizing layer are located sequentially on the water-facing side within a depth range of 30cm, 30-100cm, and 100-200cm.

4. A construction method for a microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels, characterized in that, To form a microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in any one of claims 1-3, the following steps are included: S1. Preliminary preparation: Investigate the soil of the embankment / channel, and detect and mark weak seepage channels through water injection tests; S2. Construction of the dense surface impermeable layer: Within a 30cm radius of the water-facing side, a shallow high-pressure jet grouting process is adopted, following a "bacterial solution-cementing solution-curing" cycle. The grouting pressure is controlled at 0.6-1.0MPa, and the grouting rate at 10-15L / min. First, inject the OD layer... 600 =1.2-2.0 high concentration bacterial solution and 0.8-1.5 mol / L urea, after 10-30 minutes, inject high-activity magnesium oxide slurry with MgO content of 3-8 wt%, cure for 1-2 days, and cycle 3-5 times; S3. Intermediate Transition Reinforcement Layer Construction: Within a range of 30-100cm from the water-facing side, inject OD using the same grouting pressure and rate as the surface layer. 600 Use a medium concentration of bacterial solution (0.9-1.2 mol / L), urea (0.8-1.5 mol / L), and highly active magnesium oxide slurry for 2-4 days, followed by 2-3 cycles. S4. Construction of Deep Stabilized Layer: Within a range of 100-200cm from the water-facing side, grouting holes are arranged in a grid pattern with a horizontal spacing of 50-100cm. Low-pressure grouting of 0.2-0.4MPa is used to inject OD. 600 Use a low concentration of bacterial solution (0.6-0.9 mol / L), urea (0.8-1.5 mol / L), and highly active magnesium oxide slurry for 4-7 days, followed by 1-2 cycles. S5. Overall maintenance: The three-layer structure is uniformly maintained for 3-7 days, and the maintenance water is recycled.

5. The construction method of the microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in claim 4, characterized in that, Grouting should be done from the periphery to the center. After completion, the grouting pipe should be pulled out and the grouting hole should be sealed with the original soil or cement mortar.

6. The construction method of the microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in claim 4, characterized in that, The high-concentration bacterial solution contains at least one of Bacillus pasteurellii and Diplococcus pasteurellii, and is used in conjunction with a nutrient agent that has minimal impact on the aquatic environment.

7. The construction method of the microbial-magnesium oxide gradient seepage prevention and reinforcement system for earthen embankments and channels as described in claim 4, characterized in that, In step S4, grouting holes are arranged in a grid pattern with a plane spacing of 50-100cm. The hole diameter is 20-50mm. Low-pressure grouting of 0.2-0.4MPa is used, and the grout injection volume per hole is 0.8-1.5L / m³ soil.