Alkali-activated solidified soil for resisting scouring of offshore wind power pile foundation and preparation method of alkali-activated solidified soil

Abstract

The invention discloses anti-scouring alkali-activated solidified soil for an offshore wind power pile foundation and a preparation method, and is applied to the fields of ocean engineering and geotechnical engineering. The sludge curing agent is mainly composed of sludge and a curing agent, and the dosage ratio of the sludge to the curing agent is 100: (18-21). The formula of the curing agent comprises the following components in parts by weight: 12 parts of blast furnace slag, 0-2 parts of CaO and 6-7 parts of MgO. The curing agent has the beneficial effects that solid wastes can be effectively utilized, the pollution is reduced, the carbon emission is reduced, the production cost of the curing agent is reduced, and meanwhile, in the using process, the curing effect of the curing agent on soil is improved and the strength, the stability and the anti-scouring property of the cured soil are improved by adding the alkaline exciting agent. The generated alkali-activated solidified soil can be applied to offshore wind turbine pile foundation protection, can adapt to a high chloride ion (Cl <->) concentration sludge environment, and is an effective and sustainable method.

Description

Technical Field

[0001] The invention relates to an alkali-activated solidified soil for anti-scouring of offshore wind power pile foundation, which is applied in the fields of marine engineering and geotechnical engineering. Background Art

[0002] In complex marine environments, the areas around the pile foundations of offshore wind turbines are often affected by strong currents and high-speed eddies, which carry mud and sand and lead to the formation of scour pits. This phenomenon reduces the bearing capacity of the seabed and brings engineering safety hazards such as easy overturning of the structure.

[0003] Stabilization of soil around offshore wind turbine piles with cement is a widely used method to enhance the structural integrity of these foundations. However, cement production is often associated with significant carbon emissions and energy consumption, as well as erosion potential in marine environments.

[0004] At present, solid waste is generated at a fast speed and in large quantities, posing a severe challenge to the management of industrial by-products. If industrial waste is generated in large quantities and is not properly treated, long-term storage will not only occupy precious land resources, but also cause serious pollution and environmental damage to water systems and the atmosphere. However, solid waste has a slow hydration rate when used alone, resulting in insufficient durability of stabilized soil. At the same time, the environment around the foundation of offshore wind turbines is rich in chloride ions (Cl-), which also poses an erosion threat to hydration products. Adding alkaline activators to solid waste soil can significantly accelerate the hydration reaction of waste, increase the strength of stabilized soil, and improve the ability of stabilized soil to resist erosion. Summary of the invention

[0005] Purpose of the invention: The present invention provides an alkali-activated solidified soil for offshore wind power pile foundation anti-scouring and a preparation method, wherein marine silt is mixed with a curing agent to prepare a solidified soil with high strength, good stability and scouring resistance at a high chloride ion (Cl-) content, which is applied to the protection of offshore platform pile foundations, effectively solving the scouring problem of offshore wind power pile foundations, and the treatment of marine silt and solid waste.

[0006] The technical solution adopted by the present invention is: an alkali-activated solidified soil for anti-scouring of offshore wind power pile foundation, comprising silt and a solidifying agent, wherein the mass ratio of the silt to the solidifying agent is 100:18-21;

[0007] The proportions of each component in the curing agent formula are: 12 parts of blast furnace slag, 0-2 parts of CaO, and 6-7 parts of MgO.

[0008] Preferably, the sludge is sludge with high chloride ion (Cl-) concentration.

[0009] Preferably, the blast furnace slag is ground blast furnace slag.

[0010] The preparation method of the above-mentioned alkali-activated solidified soil for offshore wind power pile foundation anti-scouring is as follows: first, blast furnace slag, CaO and MgO are fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which is stored for later use; then, screened marine silt with a certain moisture content is taken, and the curing agent is added to the marine silt according to the mass ratio, mixed and stirred to make silt-solidified soil; then, it is cured in an environment with a temperature of 20±2°C and a relative humidity of 99%±1%; finally, the solidified soil is poured onto the offshore wind power pile foundation platform by pumping and solidified into shape.

[0011] Beneficial effects:

[0012] The method for preparing alkali-activated solidified soil for offshore wind power pile foundation anti-scour uses blast furnace slag as one of the main components of the curing agent, which can effectively utilize solid waste, reduce pollution, reduce carbon emissions, and reduce the production cost of the curing agent. At the same time, during use, by adding an alkaline activator, the curing effect of the curing agent on the soil is improved, and the strength, stability and anti-scour properties of the cured soil are improved.

[0013] The generated alkali-activated stabilized soil can be used in offshore wind turbine pile foundation protection and is able to adapt to high chloride ion (Cl-) concentration silt environment, which is an effective and sustainable method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the unconfined compressive strength of alkali-activated solidified soil at different ages (PB represents cement, G represents blast furnace slag, M represents Mg+, and C represents Ca+);

[0015] Figure 2 The effect of Mg2+ on the unconfined compressive strength of alkali-activated solidified soil;

[0016] Figure 3 is the relationship between pH, moisture content and curing time;

[0017] Figure 4 Microscopic image of alkali-activated cured soil after 28 days of curing. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1

[0020] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:20; the proportions of each component in the solidifying agent formula are: 12 parts of blast furnace slag, 2 parts of CaO, and 6 parts of MgO.

[0021] First, blast furnace slag, CaO and MgO are fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which is stored for later use; then a certain amount of water and sieved marine silt are taken to make a φ39.1mm×80mm sample, which is demolded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing, pH value and moisture content.

[0022] Example 2

[0023] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:19; the proportions of each component in the solidifying agent formula are: 12 parts of blast furnace slag, 1 part of CaO, and 6 parts of MgO.

[0024] First, blast furnace slag, CaO and MgO are fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which is stored for later use; then a certain amount of water and sieved marine silt are taken to make a φ39.1mm×80mm sample, which is demolded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing, pH value and moisture content.

[0025] Example 3

[0026] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:21; the proportions of each component in the solidifying agent formula are: 12 parts of blast furnace slag, 2 parts of CaO, and 7 parts of MgO.

[0027] First, blast furnace slag, CaO and MgO were fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which was stored for later use; then a certain amount of water and sieved marine silt were taken to make a φ39.1mm×80mm sample, which was demoulded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing. The unconfined shear strength, pH value and moisture content were measured at 1 day, 3 days, 7 days, 14 days and 28 days.

[0028] Example 4

[0029] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:20; the proportion of each component in the solidifying agent formula is: 12 parts of blast furnace slag, 1 part of CaO, and 7 parts of MgO.

[0030] First, blast furnace slag, CaO and MgO were fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which was stored for later use; then a certain amount of water and sieved marine silt were taken to make a φ39.1mm×80mm sample, which was demoulded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing. The unconfined shear strength, pH value and moisture content were measured at 1 day, 3 days, 7 days, 14 days and 28 days.

[0031] Example 5

[0032] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:18.5; the proportions of each component in the solidifying agent formula are: 12 parts of blast furnace slag, 0.5 parts of CaO, and 6 parts of MgO.

[0033] First, blast furnace slag, CaO and MgO were fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which was stored for later use; then a certain amount of water and sieved marine silt were taken to make a φ39.1mm×80mm sample, which was demoulded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing. The unconfined shear strength, pH value and moisture content were measured at 1 day, 3 days, 7 days, 14 days and 28 days.

[0034] Example 6

[0035] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:19.5; the proportions of each component in the solidifying agent formula are: 12 parts of blast furnace slag, 0.5 parts of CaO, and 7 parts of MgO.

[0036] First, blast furnace slag, CaO and MgO were fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which was stored for later use; then a certain amount of water and sieved marine silt were taken to make a φ39.1mm×80mm sample, which was demoulded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing. The unconfined shear strength, pH value and moisture content were measured at 1 day, 3 days, 7 days, 14 days and 28 days.

[0037] Example 7

[0038] An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundations comprises silt and a solidifying agent; the mass ratio of the silt to the solidifying agent is 100:18; the proportions of each component in the solidifying agent formula are: 12 parts of blast furnace slag and 6 parts of MgO.

[0039] First, blast furnace slag, CaO and MgO were fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which was stored for later use; then a certain amount of water and sieved marine silt were taken to make a φ39.1mm×80mm sample, which was demoulded and placed in a curing room with a temperature of 20±2℃ and a relative humidity of 99%±1% for curing. The unconfined shear strength, pH value and moisture content were measured at 1 day, 3 days, 7 days, 14 days and 28 days.

[0040] Example 8

[0041] Example 8 is a control group, a cement-solidified soil for offshore wind power pile foundation anti-scour, including silt and cement; the mass ratio of silt to cement is 100:20;

[0042] First, cement curing agent was prepared according to the mass ratio and stored for future use; then a certain amount of water and sieved marine silt were taken to make a φ39.1mm×80mm sample, which was then placed in a curing room at a temperature of 20±2℃ and a relative humidity of 99%±1% for curing after demoulding. The unconfined shear strength, pH value, and moisture content were measured at 1 day, 3 days, 7 days, 14 days, and 28 days.

[0043] The unconfined shear strength results of the examples are shown in Table 1. Under high chloride ion concentration conditions, the strength of the alkali activated solid waste soil increased by 237.6% compared to the cement solidified soil, thus showing enhanced anti-erosion ability. In addition, under high Cl- conditions, the strength of the alkali activated solid waste soil increased with the increase of MgO content. The specific example results are shown in Figure 1-4 Therefore, using alkali activated solid waste technology as a reinforcement method for the soil around offshore wind turbine piles is an effective and sustainable method.

[0044] Table 1 Unconfined shear strength of each embodiment

[0045]

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. An alkali-activated solidified soil for anti-scouring of offshore wind power pile foundation, characterized by: It comprises sludge and a curing agent, wherein the mass ratio of the sludge to the curing agent is 100:18-21; The proportions of each component in the curing agent formula are: 12 parts of blast furnace slag, 0-2 parts of CaO, and 6-7 parts of MgO.

2. The alkali-activated solidified soil for anti-scouring of offshore wind power pile foundation according to claim 1 is characterized in that: The sludge is sludge with high chloride ion concentration.

3. The alkali-activated solidified soil for anti-scouring of offshore wind power pile foundation according to claim 2 is characterized in that: The blast furnace slag is ground blast furnace slag.

4. The method for preparing alkali-activated solidified soil for offshore wind power pile foundation anti-scour according to claim 1, 2 or 3, characterized in that: First, blast furnace slag, CaO and MgO are fully stirred and mixed according to the mass ratio to make an alkali-activated curing agent, which is stored for later use; then, screened marine silt with a certain moisture content is taken, and the curing agent is added to the marine silt according to the mass ratio, mixed and stirred to make silt-solidified soil; then, it is cured in an environment with a temperature of 20±2°C and a relative humidity of 99%±1%; finally, the solidified soil is poured onto the offshore wind power pile foundation platform by pumping and solidified into shape.

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