CN117536190A - Coral sand foundation reinforcing method and application - Google Patents
Coral sand foundation reinforcing method and application Download PDFInfo
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- 239000004576 sand Substances 0.000 title claims abstract description 95
- 235000014653 Carica parviflora Nutrition 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000003014 reinforcing effect Effects 0.000 title claims description 35
- 244000132059 Carica parviflora Species 0.000 title 1
- 241000243321 Cnidaria Species 0.000 claims abstract description 80
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 claims abstract description 37
- 229960001763 zinc sulfate Drugs 0.000 claims abstract description 37
- 229910000368 zinc sulfate Inorganic materials 0.000 claims abstract description 37
- 230000002787 reinforcement Effects 0.000 claims abstract description 14
- 238000010276 construction Methods 0.000 claims abstract description 11
- 238000005507 spraying Methods 0.000 claims abstract description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 239000013535 sea water Substances 0.000 claims description 2
- 230000006641 stabilisation Effects 0.000 claims description 2
- 238000011105 stabilization Methods 0.000 claims description 2
- 238000011049 filling Methods 0.000 abstract description 16
- 239000013505 freshwater Substances 0.000 abstract description 9
- 238000009991 scouring Methods 0.000 abstract description 5
- 238000007664 blowing Methods 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 239000010419 fine particle Substances 0.000 abstract description 2
- 230000007774 longterm Effects 0.000 abstract description 2
- 230000035699 permeability Effects 0.000 description 20
- 239000002245 particle Substances 0.000 description 19
- 238000012360 testing method Methods 0.000 description 18
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 16
- 238000006243 chemical reaction Methods 0.000 description 13
- 239000011148 porous material Substances 0.000 description 12
- 238000005516 engineering process Methods 0.000 description 11
- 229910052602 gypsum Inorganic materials 0.000 description 11
- 239000010440 gypsum Substances 0.000 description 11
- 230000008569 process Effects 0.000 description 11
- 101000965313 Legionella pneumophila subsp. pneumophila (strain Philadelphia 1 / ATCC 33152 / DSM 7513) Aconitate hydratase A Proteins 0.000 description 10
- 239000000047 product Substances 0.000 description 9
- 229910000019 calcium carbonate Inorganic materials 0.000 description 8
- 239000013078 crystal Substances 0.000 description 8
- 238000002791 soaking Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000011701 zinc Substances 0.000 description 6
- 150000004683 dihydrates Chemical class 0.000 description 5
- 229910052725 zinc Inorganic materials 0.000 description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
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- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 241001465754 Metazoa Species 0.000 description 2
- 206010040844 Skin exfoliation Diseases 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
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- 125000004122 cyclic group Chemical group 0.000 description 2
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- 239000001095 magnesium carbonate Substances 0.000 description 2
- 235000014380 magnesium carbonate Nutrition 0.000 description 2
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 2
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 2
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- 244000005700 microbiome Species 0.000 description 2
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- 229910021646 siderite Inorganic materials 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 229910021532 Calcite Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical group [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 108010046334 Urease Proteins 0.000 description 1
- 239000003674 animal food additive Substances 0.000 description 1
- 230000001580 bacterial effect Effects 0.000 description 1
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- 229940105847 calamine Drugs 0.000 description 1
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- 230000000052 comparative effect Effects 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 229910052864 hemimorphite Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
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- 239000007788 liquid Substances 0.000 description 1
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- 150000003839 salts Chemical class 0.000 description 1
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- 238000004626 scanning electron microscopy Methods 0.000 description 1
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- 239000011787 zinc oxide Substances 0.000 description 1
- 235000014692 zinc oxide Nutrition 0.000 description 1
- CPYIZQLXMGRKSW-UHFFFAOYSA-N zinc;iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Fe+3].[Fe+3].[Zn+2] CPYIZQLXMGRKSW-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/148—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing calcium sulfate formed in situ, e.g. by the reaction of iron sulfate with lime
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
Abstract
The invention discloses a coral sand foundation reinforcement method and application, which belong to the technical field of coral island reef engineering, and specifically comprise the following steps: spraying zinc sulfate solution on the surface of the coral sand foundation. The invention also discloses application of the method in the blowing and filling construction of the coral island foundation. The invention can greatly reduce coral sand loss caused by wave scouring during hydraulic filling; after the hydraulic filling foundation is formed, the anti-seepage and anti-erosion performances of the foundation can be improved, the loss of fine particles is reduced, the seepage damage of the foundation is prevented, and the long-term stability and safety of the foundation and an engineering building are ensured; meanwhile, the low-permeability reinforcement layer can reduce the loss of underground fresh water, promote the formation of underground fresh water, accelerate the conservation of island underground fresh water and promote the formation of ecological islands.
Description
Technical Field
The invention belongs to the technical field of coral island-reef engineering, and particularly relates to a coral sand foundation reinforcing method and application.
Background
The coral sand has irregular particle shape, contains a plurality of internal pores, and has the characteristics of wide grading and large permeability. The coral reefs are located in tropical and subtropical sea areas, the environment is severe, the hydrodynamic force is strong, storm and strong precipitation are frequent, during the hydraulic reclamation construction, the loose coral reef sand is lost due to wave current scouring, and the hydraulic reclamation construction efficiency is low; after the foundation is filled, under the action of storm flushing and tidal seepage, pore water seepage in the coarse-grained soil foundation causes fine-grained soil loss, soil holes are formed in the lower part of the foundation, the soil holes gradually expand and develop upwards, and finally the foundation is unstable and the ground is collapsed, and even the engineering building is unstable and damaged. The strong permeability causes that island underground freshwater bodies are difficult to form, the freshwater conservation speed is extremely slow, and the development of ecological vegetation is extremely unfavorable.
In the prior art, the MICP technology is commonly used for reinforcing the surface of the coral sand foundation, but in the actual operation process, the MICP technology has the defects of complex operation, remarkable non-uniformity in reinforcement, multiple reinforcing times, long period and the like, the method can be carried out only by a few days to more than one week, and the used microorganisms are fragile and are difficult to adapt to the severe environment of the island engineering site.
Therefore, how to provide a coral sand reinforcing method with simple operation, good reinforcing effect, high efficiency and good environmental adaptability is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
In order to solve the technical problems, the invention provides a coral sand foundation reinforcing method and application, which can prevent reef sand loss, reduce the risk of foundation settlement and collapse and promote the conservation of island reef underground fresh water.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a method for reinforcing coral sand foundation features that zinc sulfate solution is sprayed on the surface of coral sand foundation.
Preferably, the spraying time is that zinc sulfate solution is sprayed on the surface of the coral sand foundation when a layer of coral reef sand is blown and filled on the reef during the blowing and filling construction of the coral island foundation after sea water is refunded and the reef is exposed out of the water surface.
Preferably, the concentration of the zinc sulfate solution is 0.5-1.5 mol/L.
Preferably, the thickness of the reinforcement is 5-10 cm.
Wherein, the spraying amount of the zinc sulfate solution is determined according to the field reinforcement thickness, and only coral sand with the surface layer of 5cm to 10cm is solidified.
Preferably, the curing time is no more than 2 hours.
Preferably, the foundation is compacted by vibration before the zinc sulfate solution is sprayed, so that the reinforcing effect is better. The process can be selected according to the actual condition of the site, and if the site condition is not available, the process can be not compacted.
The reinforcement principle of the invention is as follows:
the coral sand contains calcium carbonate (CaCO) 3 ) The present invention uses zinc sulfate solution (ZnSO 4 ) Chemically reinforcing coral sand to obtain a reaction product of magnesite (ZnCO) 3 ) And gypsum dihydrate (CaSO) 4 ·2H 2 O) are solid substances, and byproducts which are harmful to the environment are not present in the product. The corresponding chemical reaction formula is as follows:
Zn 2+ +SO 4 2- +CaCO 3 →ZnCO 3 ↓+CaSO 4 ·2H 2 O↓ (1)
the method of the invention has the advantages that the products are all solid minerals which are insoluble in water in the process of cementing and reinforcing the coral sand, wherein, the hardness of the calamine is larger than that of calcite, which can improve the hardness of the coral sand, reduce the breakage of particles, and the gypsum fills the pores among the coral sand particles and forms a network structure connected with each other as cementing agent among the coral sand particles, and fills the pores of the coral sand particles, so that the coral sand is more compact.
Second, the salts used in the present invention are completely soluble in water, which means that toxicological effects in the aquatic environment must be considered. The zinc sulfate solution of the invention has no stimulation to skin, and can be used as nutrient for animals when zinc is lacking, feed additive for animal husbandry and zinc fertilizer for crops. In the period of damping, zinc sulfate solution and coral sand exposed out of water surface are reacted completely to produce siderite and gypsum, and both minerals are solid matter harmless to environment and insoluble in water. In addition, the reaction of zinc sulfate and coral sand is a rapid process, and when tidal water is removed and the foundation is higher than the water surface in the island hydraulic reclamation project, the zinc sulfate solution is sprayed on a small scale, so that the zinc sulfate can be completely consumed in the reaction under the condition of reasonably controlling the dosage, and the marine environmental pollution caused by a large amount of loss is avoided, and therefore, the technical scheme of the invention is harmless to the environment. If the method is used for temporarily reinforcing the coral sand pile slope and the foundation pit slope, the dosage is small, and the zinc sulfate solution and the coral sand fully react and cannot flow into the ocean to pollute the ocean environment.
More preferably, the method specifically comprises the following steps:
during the hydraulic filling construction of the coral island foundation, the foundation is exposed out of the water surface during refund, and zinc sulfate solution with the concentration of 0.5 mol/L-1.5 mol/L is sprayed on the surface of the coral sand foundation at the moment to cement and strengthen the loose coral sand foundation; the foundation may be vibration compacted (or not) when conditioned prior to spraying the solution. When the method is specifically used, the reinforcement thickness is set to be 5 cm-10 cm, and the optimal solution concentration and the reinforcement times can be determined after the test is performed on site. The sand body is not trampled in the reinforcing process so as not to damage the inter-grain cementing which is formed, and after 2 hours of solidification, the hydraulic filling construction is continued on the original foundation.
The invention also discloses application of the coral sand foundation stabilization method in the hydraulic reclamation construction of the coral island foundation.
Compared with the prior art, the invention has the following advantages and technical effects:
the invention provides a method for rapidly cementing and reinforcing a coral sand foundation and application thereof, which can greatly reduce coral sand loss caused by wave scouring during hydraulic filling; after the hydraulic filling foundation is formed, the anti-penetration and anti-erosion performances of the foundation can be improved, the loss of fine particles is reduced, the penetration damage of the foundation is stopped, and the long-term stability of the foundation and the engineering building is ensured; meanwhile, the low-permeability cementing reinforcement layer can reduce the loss of underground fresh water, promote the formation of underground fresh water, accelerate the conservation of island-reef underground fresh water and promote the construction of ecological islands.
The method provided by the invention is simple to operate, only needs to spray the zinc sulfate solution on the coral sand foundation for 1-2 times, has no other additional requirements on the use environment, has good reinforcing effect, has strong flowability of the used solution, can infiltrate into fine pores, can uniformly reinforce, and is far superior to the MICP technology in feasibility of engineering application. In addition, the zinc sulfate and the coral sand react rapidly, the coral sand is glued to form higher strength within 2 hours, a remarkable reinforcing effect can be obtained, the method is suitable for island reef hydraulic filling engineering during a refund period, no requirements are imposed on the environment temperature, humidity and microorganism environment, and the higher the temperature of the offshore island reef is, the faster the reaction is, and the method has better applicability to the island reef engineering environment.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application, illustrate and explain the application and are not to be construed as limiting the application. In the drawings:
FIG. 1 is a graph showing the comparison of the coral sand reinforcement before and after the coral sand reinforcement in example 1;
wherein, (a) is unconsolidated and reinforced calcareous sand particles, (b) is unconsolidated and reinforced calcareous sand particles, (c) is consolidated and reinforced calcareous sand, (d) is consolidated and reinforced calcareous sand, (e) is consolidated and reinforced calcareous sand, and (f) is consolidated and reinforced calcareous sand;
FIG. 2 is an EDS spectrum analysis chart of coral sand before and after curing;
FIG. 3 shows examples 1-3 of different ZnSO 4 The permeability coefficient and the mass increase rate of each dry density cemented coral sand under the concentration change with time;
wherein (a) is a dry density of 1.54g/cm 3 (b) a dry density of 1.62g/cm 3 (c) a dry density of 1.70g/cm 3 ；
FIG. 4 shows the variation of the mass loss rate of the sample with the number of dry and wet cycles;
wherein (a) is a dry density of 1.54g/cm 3 (b) a dry density of 1.70g/cm 3 ；
Figure 5 is a graph of the cementitious sample after 16 dry and wet cycles.
FIG. 6 is a graph showing the MICP-cured calcareous sand permeability coefficient results;
FIG. 7 is a graph showing the MICP-cured calcareous sand permeability coefficient results.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The zinc sulfate solution in the embodiment of the invention is prepared by using pure water as a solvent, and the solution is prevented from contacting with fragile parts of a body in the preparation process.
Example 1
A method for rapidly reinforcing coral sand foundation comprises the following steps:
during the construction period of blowing and filling the coral island foundation, the foundation is exposed out of the water surface during refund, at the moment, zinc sulfate solution with the concentration of 0.5mol/L is sprayed on the surface of the coral sand foundation, the spraying amount is determined according to the site reinforcing condition, and only the coral sand on the surface layer of 5 cm-10 cm is needed to be cemented and solidified. And reinforcing the loose coral sand foundation. And before spraying the solution, vibrating and compacting the foundation. In specific use, the reinforcing thickness is set to be 5 cm-10 cm. The sand body is not trampled in the reinforcing process so as not to damage the inter-grain cementation which is formed, and after the cementation is solidified for 2 hours, the hydraulic filling construction can be continued on the original foundation.
Example 2
A method for rapidly reinforcing coral sand foundation is different from example 1 in that the concentration of the sprayed zinc sulfate solution is 1.0mol/L.
Example 3
A method for rapidly reinforcing coral sand foundation is different from example 1 in that the concentration of the sprayed zinc sulfate solution is 1.5mol/L.
Comparative example 1
A method for reinforcing coral sand foundation by using conventional MICP technology specifically comprises the following steps:
the basic principle of MICP technology is that carbonate ions generated by urea hydrolysis by urease-producing bacteria react with free calcium ions in solution and combine to produce calcium carbonate minerals with cementation. The MICP technology comprises the following specific steps: slowly injecting bacterial liquid into the calcareous sand to ensure that bacteria are fully and uniformly attached to the surfaces of coral sand particles, slowly injecting reaction liquid, and hydrolyzing urea in the reaction liquid under the action of bacteria to generate carbonate ions which react with calcium ions to generate calcium carbonate. This process needs to be continued several times to ensure that sufficient calcium carbonate mineral is formed inside the sample to enhance the curing effect. The reaction equation is as follows:
FIGS. 6 and 7 are the results of the permeability coefficient of the calcareous sand after the treatment using MICP technique in the reference, wherein FIG. 6 is the results of the permeability coefficient of the MICP-cured calcareous sand (Ma Ruinan, guo Gongxian, cheng Xiaohui, etc.. Microbial mixing and consolidation calcareous sand permeability characteristic test study [ J ]. Geotechnical mechanics, 2018,39 (S2): 217-223.), and FIG. 7 is the results of the permeability coefficient of the MICP-cured calcareous sand (Fang Xiangwei, shen Chunni, chu Jian, etc.. Microbial deposition of calcium carbonate-cured coral sand test study [ J ]. Geotechnical mechanics, 2015,36 (10): 2773-2779.). Because of the different grading, compactness and control variables, the MICP method cannot be compared with the method under the unified standard, but it can be confirmed that the two methods have good curing effect, the permeability coefficient of the cured calcareous sand is obviously reduced, but the MICP technology has slightly complicated operation steps, the technology has simple operation steps, and the technology is obviously superior to the MICP technology in curing efficiency and environmental adaptability.
The technical effects are as follows:
1. microscopic test
The original coral sand particles are loose and are easy to run off under the scouring action of water flow. After the zinc sulfate solution is consolidated and solidified, the pores among coral sand particles are filled with gypsum, the consolidated body is formed, and the water flow scouring erosion resistance is obviously enhanced. The coral sand particles before and after curing in example 1 were scanned by SEM scanning electron microscopy, and as shown in fig. 1, it can be seen that the surface pores of the coral sand before curing are relatively obvious, the surface pores after curing are covered with new products, and obvious rod-shaped products are filled between the particles. Needle-shaped dihydrate gypsum generated by the reaction of zinc sulfate and calcium carbonate can grow in a lap joint manner among coral sand particles, and plays a role similar to a bridge; secondly, the tiny spherical magnesite generated by the reaction is further filled and coated with coral sand on the basis. The gypsum crystals in the product generated in the invention are larger, which plays a main role in filling pores, while the siderite crystals are smaller, and are mainly dispersed on the surfaces of gypsum and coral sand, which plays an auxiliary reinforcing role. Therefore, when the inter-particle pores are smaller, the dihydrate gypsum crystals can be mutually overlapped, and the fine rhombohedral zinc ore crystals can be well reserved in the dehydrate gypsum crystals, so that the effect of further filling and reinforcing is achieved; when the pores are larger, the dihydrate gypsum crystals are not effectively overlapped, and the rhombohedral zinc ore crystals are easy to run off among the larger pores, so that the reinforcing effect is poor. As shown in part (d) of FIG. 1, the interparticle voids in the lower right region are larger and deeper than those in the upper left region, thus resulting in poor cement filling. At this time, the spraying amount of the zinc sulfate solution should be appropriately increased, or the secondary spraying reinforcement should be performed.
EDS spectrum analysis is carried out on coral sand before and after solidification, the technology is to fix electron beams at a certain point in a sample for qualitative or quantitative analysis, and each element in a spectrum point peak pattern graph shows a peak in the graph, so that the element contained in the sample can be seen. The test results are shown in FIG. 2 and Table 1. P (P) 1 The point test results show that the main component of the undisturbed sand sample is calcium carbonate. P pair P 2 The main elements are Zn, C and O, so that the product of the method can be judged as the product of the calanite. P (P) 3 Since Ca and S elements at the point are close to 1:1 and the crystal morphology is needle-like, it can be inferred thatIs dihydrate gypsum.
TABLE 1EDS analysis results
2. Penetration test
The coral sand was taken for a permeation test, and the original coral sand cylindrical sample had a diameter of 50mm and a height of 50mm (FIG. 5). The permeability test adopts two indexes of permeability coefficient and mass increase rate to reflect the reinforcing effect, the permeability coefficient is the index which shows the most visual permeability of the sample, and the total atomic number of the product after the zinc sulfate cementation reaction is increased, so that the sample mass increase rate can be used for representing the proceeding degree of the reaction.
The test treatment mode adopts a soaking method, and each group of samples is fixedly soaked by 500mL of zinc sulfate solution, wherein the concentration of the zinc sulfate solution is respectively 0.5mol/L, 1.0mol/L and 1.5mol/L, and the results are shown in FIG. 3 and Table 2.
As shown in FIG. 3, the zinc sulfate solution concentration is high in the early stage of the soaking treatment, the reaction rate is faster, so that the mass is increased more, the reaction rate is slowed down as the zinc sulfate is continuously consumed as the reaction continues, and the sample mass is basically stable after 24 hours of the soaking treatment.
TABLE 2 penetration comparison of 36h samples for soaking treatment
Table 2 compares the permeabilities of the 36h soak treated sample to the undisturbed untreated sample (undisturbed sample), where the reduction refers to the ratio of the difference in permeability coefficients to the undisturbed permeability, a greater value indicating a greater reduction in permeability coefficient and a better reinforcement. As shown in Table 2, the permeability coefficient of the sample after soaking for 36 hours is reduced by 70.17% -95.79%, which shows that the permeability coefficient can be obviously reduced by adopting a zinc sulfate solution to cure coral sand.
3. Influence of Dry-Wet circulation on Zinc sulfate cemented coral Sand
The dry-wet cycle test is carried out according to a standard, and specifically comprises the following steps:
the artificial island foundation can repeatedly undergo the cyclic process of soaking and dewatering under the action of tides, but sand layers are not fully saturated or dried, and most sea areas in south China sea are mainly tidal in an irregular full-day manner, so that the test is designed according to the full-day tide, namely, the test is carried out by adopting a dry-wet cyclic mode for 12 hours each. Meanwhile, the wet circulation temperature is selected to be close to the average surface water temperature of the south China sea. In the process of damping, the temperature of the blowing and filling reef sand is close to 50 ℃ in the process of high ultraviolet irradiation, so that the dry cycle temperature is set to 50 ℃, the aim is to simulate the field environment temperature and accelerate the drying of samples, and the durability of the zinc sulfate cemented coral sand is better evaluated, so that the dry cycle time in a dry-wet cycle test lasts for 12 hours, the maintenance temperature is 50+/-1 ℃, the samples are soaked in deionized water after the dry cycle is finished, the maintenance temperature is 20+/-1 ℃ and lasts for 12 hours, and the dry-wet cycle test is one-time dry-wet cycle test. The dry-wet cycle test was performed 16 times in total, the mass loss rate of the samples was recorded after the end of each cycle, and the permeation test was performed on the samples after the 0 th, 4 th, 8 th, 12 th, and 16 th cycles.
FIG. 4 is a graph showing the variation of the mass loss rate with the number of dry and wet cycles, wherein H (hour) of H2C0.5 in the legend represents the soaking treatment time period of 2H, and C0.5 represents ZnSO 4 The concentration of the solution was 0.5mol/L.
As can be seen from fig. 4, all samples were substantially stable in quality after 16 dry and wet cycles, and the final mass loss rate was less than 4%, demonstrating that the coral sand samples after zinc sulfate consolidation had better durability.
Fig. 5 is a sample after 16 cycles of dry and wet. The different samples were distinguished using the identification of a-b-c, where a represents the initial dry density (g/cm 3 ) B represents the treatment time (h), and c represents the concentration (mol/L) of the zinc sulfate solution. The right-hand 36h sample in fig. 5 has higher integrity and less mass loss than the left-hand 2h sample, because the newly formed product continuously fills the inter-particle voids, progressively increases in cementation,the sample durability is better.
As can be seen from FIG. 5, the sample treated with the zinc sulfate solution at a lower concentration (0.5 mol/L) after the curing treatment is less likely to suffer from peeling loss of sand particles. This suggests an increase in ZnSO 4 The concentration of the solution aids in the cementation reaction and thus facilitates durability improvement. The first row in FIG. 5 has an initial dry density of 1.54g/cm 3 1.70g/cm higher than the second row 3 The sample erosion damage of the (C) is more serious, and not only is the sand particles peeled off in the weak area of the edge of the sample, but also the surface cementing filling is damaged to a certain extent. As can be seen by comparing FIG. 4, the initial dry density is 1.70g/cm 3 The sample mass loss rate is smaller and the curve is flatter, which shows that the erosion damage caused by the dry and wet circulation has less influence on the sample mass loss, and the mass loss mainly originates from the damage of the edge of the sample. Initial Dry Density of 1.54g/cm 3 In contrast, the samples of (a) have poor cementing effect, and once sand particles at the edges of the samples are peeled off, the mass loss rate is obviously increased on the curve, but the phenomenon of peeling of the particles does not occur every cycle, so that the curve shows more complex change trend, and the cured samples have better durability as a whole.
The foregoing is merely a preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily conceivable by those skilled in the art within the technical scope of the present application should be covered in the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (7)
1. A method for reinforcing coral sand foundation is characterized in that zinc sulfate solution is sprayed on the surface of the coral sand foundation.
2. The method for reinforcing a coral sand foundation according to claim 1, wherein the spraying time is when a layer of coral reef sand is blown onto the reef after sea water is refunded and the reef is exposed to the water surface.
3. A method for reinforcing a coral sand foundation according to claim 1, wherein the concentration of the zinc sulfate solution is 0.5 to 1.5mol/L.
4. A method of reinforcing a coral sand foundation according to claim 1, wherein the thickness of the reinforcement is 5-10 cm.
5. A method of reinforcing a coral sand foundation as defined in claim 1, wherein the curing time is no more than 2 hours.
6. A method of reinforcing a coral sand foundation as defined in claim 1, wherein the foundation is vibration compacted prior to spraying the zinc sulfate solution.
7. The use of a coral sand foundation stabilization method according to any one of claims 1 to 6 in a coral island foundation reclamation construction.
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| CN110272221A (en) * | 2019-05-27 | 2019-09-24 | 深圳大学 | A kind of preparation method of modified coral sand concrete |
| CN115075221A (en) * | 2022-07-15 | 2022-09-20 | 中国科学院武汉岩土力学研究所 | Quick curing method for calcareous sand |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110272221A (en) * | 2019-05-27 | 2019-09-24 | 深圳大学 | A kind of preparation method of modified coral sand concrete |
| CN115075221A (en) * | 2022-07-15 | 2022-09-20 | 中国科学院武汉岩土力学研究所 | Quick curing method for calcareous sand |
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