Fluidized solidified soil as well as preparation method and application thereof

Abstract

The invention relates to the technical field of building materials, in particular to flow-state solidified soil as well as a preparation method and application thereof. The flow-state solidified soil comprises the following components in percentage by mass: 50%-60% of muck, 35%-40% of water and 5%-13% of a curing agent, wherein the curing agent is prepared from the following components in parts by weight: 5 to 25 parts of cement clinker, 25 to 50 parts of superfine slag powder, 10 to 25 parts of fly ash, 10 to 20 parts of waste gypsum, 10 to 20 parts of mountain flour slag, 1 to 3 parts of anti-dispersing agent and 1 to 5 parts of water reducing agent. According to the invention, the defect that the plugging effect is poor when cement paste is used as a drilling hole exploration plugging agent at present can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and more particularly, to a fluidized solidified soil and its preparation method and application. Background Art

[0002] Before the excavation of a foundation pit, exploration drilling operations are generally carried out on the site. The depth of the exploration drilling is generally more than 3 times the depth of the foundation pit excavation, and most of the exploration drilling depths enter or pass through the confined aquifer. After the foundation pit is excavated, the exploration drill holes that penetrate the confined aquifer become the channels for the upwelling of the confined water, which will cause a large amount of underground confined water to flow into the foundation pit along the exploration drill holes. To prevent the exploration drill holes from becoming the channels for the confined water to flow into the foundation pit, generally, cement slurry is used to block the exploration drill holes before the foundation pit excavation. That is, cement slurry is injected from the bottom of the hole upward. The cement slurry discharges the accumulated water in the hole from bottom to top and then fills the exploration drill hole. After the cement slurry solidifies, the exploration drill hole can be completely blocked.

[0003] However, the cement slurry has shrinkage, and the solidified cement slurry has shrinkage, which easily leads to the non-compactness of the closed holes and there is a risk of the confined water flowing upward along the gaps. At the same time, since cement only undergoes a hydration reaction with water and does not undergo a chemical reaction with soil, the shear strength at the interface between the cement slurry and the wall of the exploration drill hole is low and is easily broken through by the underground confined water with a certain pressure and then flows into the foundation pit. In addition, since the concentration of the cement slurry is relatively dilute, it cannot completely discharge the accumulated water in the hole, so there is inevitably some water that cannot be discharged locally, forming holes left over later, thereby reducing the blocking effect of the cement slurry. Summary of the Invention

[0004] The problem solved by the present invention is to improve the poor blocking property existing when cement slurry is used as a blocking agent for exploration drill holes at present.

[0005] To solve the above problems, the present invention provides a fluidized solidified soil. By mass percentage, the fluidized solidified soil comprises 50% to 60% of muck, 35% to 40% of water, and 5% to 13% of a curing agent;

[0006] Wherein, the curing agent comprises the following components in parts by weight: cement clinker: 5 parts to 25 parts, granulated blast-furnace slag powder: 25 parts to 50 parts, fly ash: 10 parts to 25 parts, waste gypsum: 10 parts to 20 parts, stone powder residue: 10 parts to 20 parts, anti-dispersant: 1 part to 3 parts, water reducing agent: 1 part to 5 parts.

[0007] Optionally, in the curing agent, by mass percentage, the calcium oxide content in the fly ash is 5% to 10%.

[0008] Optionally, in the curing agent, the waste gypsum is desulfurized gypsum and / or phosphogypsum.

[0009] Optionally, in the curing agent, the particle size of the stone powder residue is less than 0.5 mm.

[0010] Optionally, in the curing agent, the composition of the anti-dispersant includes polyacrylamide.

[0011] Optionally, in the curing agent, the water reducing agent is naphthalene sulfonate formaldehyde condensate.

[0012] Optionally, the particle size of the muck is less than or equal to 1 mm.

[0013] In a second aspect, the present application provides a method for preparing fluid-solidified soil, including:

[0014] Soaking the muck in water to obtain a muck soaking solution;

[0015] Mixing the curing agent powder and water evenly to prepare a curing agent slurry;

[0016] Mixing the curing agent slurry with the muck soaking solution and stirring to obtain fluid-solidified soil.

[0017] Optionally, in the muck soaking solution, the mass ratio of muck to water is 1:(0.8 to 1);

[0018] And / or, the mass ratio of the muck to the curing agent powder is 1:(0.2 to 0.25);

[0019] And / or, in the curing agent slurry, the mass ratio of the curing agent powder to water is 1:(1.5 to 3).

[0020] In a third aspect, the present application further provides the application of the above-mentioned fluid-solidified soil in plugging boreholes.

[0021] The beneficial effects of the fluid-solidified soil of the present invention are as follows:

[0022] Compared with the traditional method of filling holes with cement slurry, the present invention uses a cementitious material mainly composed of industrial solid wastes (such as slag powder, fly ash, waste gypsum, stone powder residue) as a curing agent to replace most of the cement, and mixes the curing agent and the muck at the construction site to prepare fluid-solidified soil. Since the tap water in the traditional cement slurry is 35 - 40% and the cement is 60 - 65%. Therefore, it is equivalent that 60 - 65% of the cement material in the original cement slurry is replaced by 5 - 13% of the curing agent and 50 - 60% of the muck, and the material cost is greatly reduced. Using the fluid-solidified soil mixed with the curing agent and the site muck to fill holes has better micro-expansibility and excellent interfacial shear strength compared with the traditional cement slurry, and the impermeability, sealing and plugging performance of the surveyed boreholes after filling are better. Description of the Drawings

[0023] Figure 1Schematic diagram of the distribution of aquifers in the foundation pit engineering of the present invention;

[0024] Figure 2 Schematic diagram when the fluidized solidified soil is injected into the exploration borehole in an exemplary embodiment of the present invention

[0025] Explanation of reference numerals: 1, fluidized solidified soil; 2, exploration borehole; 3, cohesive soil layer; 4, confined aquifer; 5, unconfined aquifer; 6, cut-off curtain. Detailed implementation manners

[0026] To make the above objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below.

[0027] As Figure 1 and Figure 2 shown, the strata below the general water level are all called aquifers. The strata often consist of an interbedded distribution of impermeable cohesive soil layers 3 and water-rich sand layers. Generally, the first sand layer below the water level is called the unconfined aquifer 5, and the second sand layer below the water level is called the confined aquifer 4. The confined aquifer 4 is covered by an impermeable cohesive soil layer 3 on the upper part. Once the roof is penetrated, the groundwater will spout out from the hole until the water level is the same as the water level of the outer unconfined aquifer 5.

[0028] Generally speaking, when drilling a well from the ground surface, there is no water in the well before penetrating the water-resisting roof. After uncovering the confined aquifer 4, the water level in the drilled well will rise to a certain height above the bottom boundary of the water-resisting roof. Such a drilled well is called a confined well. In general plain areas, the water level of the confined aquifer 4 is basically the same as the water level of the cohesive soil layer 3, that is, once the roof of the confined aquifer 4 is penetrated, the groundwater will quickly rise to a height close to or the same as the water level of the unconfined aquifer.

[0029] Referring to Figure 1 shown, for the foundation pit engineering, there should be no holes penetrating the confined aquifer 4 before the foundation pit excavation. Because currently, the depths of most exploration boreholes 2 have entered or passed through the confined aquifer 4, while the depth of the cut-off curtain 6 in general foundation pit engineering does not enter the confined aquifer 4. Therefore, after the foundation pit is excavated, the exploration borehole 2 penetrating the confined aquifer 4 will become a channel for the upwelling of confined water, resulting in continuous inflow of confined water into the foundation pit, and it is impossible to drain it by drainage measures, and the treatment is extremely difficult.

[0030] Therefore, in order to prevent the exploration borehole from becoming a channel for the inflow of confined water into the foundation pit, generally, the exploration borehole will be blocked with cement slurry before the foundation pit excavation. In order to improve the defects existing when the exploration borehole is blocked with cement slurry, the present invention provides a fluidized solidified soil.

[0031] In a first aspect, on a mass percentage basis, the fluidized solidified soil in the present invention comprises 50% to 60% of muck, 35% to 40% of water, and 5% to 13% of a solidifying agent. Among them, the solidifying agent comprises components in the following parts by weight: clinker: 5 parts to 25 parts, granulated blast-furnace slag powder: 25 parts to 50 parts, fly ash: 10 parts to 25 parts, waste gypsum: 10 parts to 20 parts, stone powder residue: 10 parts to 20 parts, anti-dispersant: 1 part to 3 parts, water-reducing agent: 1 part to 5 parts.

[0032] First of all, compared with the traditional method of filling holes with cement slurry, the present invention uses a cementitious material mainly composed of industrial solid waste (such as granulated blast-furnace slag powder, fly ash, waste gypsum, stone powder residue) as a solidifying agent to replace most of the cement, and mixes the solidifying agent with the muck at the construction site to form fluidized solidified soil. Since tap water accounts for 35 - 40% and cement accounts for 60 - 65% in the traditional cement slurry. Therefore, 60 - 65% of the cementitious material in the original cement slurry is replaced by 5 - 13% of the solidifying agent and 50 - 60% of the muck, resulting in a significant reduction in material costs.

[0033] Secondly, in the solidifying agent of the present invention, waste gypsum can react with water and some clay minerals to form ettringite minerals, with the volume increasing by about 10% compared to the original clay minerals. Therefore, the fluidized solidified soil formed by mixing the solidifying agent and the muck at the site has a slight swelling property compared with the traditional cement slurry, which can make the filled exploration borehole have better impermeability, sealing or plugging performance. At the same time, the addition of the anti-dispersant in the solidifying agent makes the fluidized solidified soil not segregate and disperse underwater, and water is not easily introduced into the interior of the fluidized soil, thus always maintaining an agglomerated state and not being washed away by high-pressure water, further ensuring the sealing or plugging performance.

[0034] Furthermore, the fluidized solidified soil of the present invention has greater viscosity than the traditional cement slurry, and can discharge more accumulated water in the hole outside the hole, so the filling degree is higher. After injecting the viscous fluidized solidified soil to the bottom of the hole, during the upward return process of the fluidized solidified soil in the borehole, it will lift the accumulated water in the hole upward and discharge it outside the hole. While the traditional cement slurry is much thinner and cannot completely discharge the accumulated water in the hole during the upward return process from the bottom of the hole. Therefore, the filling degree of the fluidized solidified soil is higher, making the filled exploration borehole have better impermeability.

[0035] Finally, the pore wall interface formed by the flowable solidified soil of the present invention has high strength and good impermeability. Since traditional cement materials do not chemically react with soil, the interface between the cement slurry and the pore wall is relatively clear, with an obvious demarcation and low interface shear strength. However, the curing agent in the flowable solidified soil of the present invention can further chemically react with the soil on the pore wall. Therefore, there are more hydrated calcium silicate gel minerals and ettringite minerals at the interface between the flowable soil and the soil, having a higher interface shear strength. Thus, compared with the holes filled with traditional cement slurry, it is difficult for the underground confined water to penetrate upward through the interface into the foundation pit range.

[0036] In summary, the present invention provides a flowable solidified soil, which can improve the defects existing when using cement slurry to plug exploration boreholes and has good sealing performance for exploration boreholes.

[0037] In some alternative embodiments, the muck in the above-mentioned flowable solidified soil may be granite weathered soil, and the particle size of the muck is less than or equal to 1 mm, that is, the muck is sieved to remove particles with a particle size above 1 mm, which is beneficial to ensuring that the flowable soil has good fluidity and preventing larger particles from clogging the mortar pump.

[0038] In some alternative embodiments, in the curing agent, calculated by mass percentage, the calcium oxide content in fly ash is 5% to 10%.

[0039] Specifically, in the embodiments of the present invention, the fly ash is Class I fly ash, and the calcium oxide content is maintained within a certain range. The calcium oxide reacts with the water in the concrete to generate calcium hydroxide, and the calcium hydroxide further reacts with other components in the curing agent such as sodium silicate to generate substances such as calcium silicate gel. These gels can fill the pores of the concrete, making the concrete more dense, thereby improving the plugging effect. In addition, since fly ash contains a large amount of active SiO2, Al2O3, Fe2O3, etc., it is acidic and can neutralize alkaline bentonite, making the reaction between the flowable solidified soil and the alkaline bentonite slurry more sufficient. At the same time, due to the fine particles of fly ash, it has a good filling effect on the voids formed by cement and montmorillonite minerals, and can further improve the strength of the flowable solidified soil.

[0040] In some alternative embodiments, the waste gypsum in the curing agent is desulfurized gypsum and / or phosphogypsum, wherein the content of CaSO4·2H2O ≥ 90%, and the specific surface area ≥ 300m 2 / kg. The desulfurized gypsum is alkaline. When it reacts with fine soil particles together with slag powder as an alkaline activator, it can not only accelerate the reaction between slag powder and soil particles, but also has the dual functions of cementing soil particles and expanding to fill pores. Under the action of alkaline activators such as gypsum, the slag powder will chemically react with SiO2 in the soil to generate calcium silicate hydrate (C-S-H). Calcium silicate hydrate (C-S-H) can cement some unreacted particles, agglomerate and deposit them together and gradually harden, and finally become a brittle hardened body.

[0041] In some alternative embodiments, the anti-dispersant in the curing agent is a polymer. Specifically, such as polyacrylamide or cellulose ether, etc. The polymer can form a three-dimensional network space structure in water, wrap or lock the soil particles in the network, and prevent the segregated flow soil from segregating or separating from water during the underwater flow process. At the same time, it can ensure that the segregated flow soil has good viscosity. During the upward return process in the hole, compared with traditional cement materials, it will never segregate, and water and mud will not separate, and all the accumulated water can be pushed out of the hole. At the same time, in order to further improve the water retention performance of the segregated flow solidified soil, other additives such as calcium-based bentonite and water retention agent can be further added.

[0042] In some alternative embodiments, the water reducing agent in the curing agent is a naphthalene sulfonate formaldehyde condensate, which is mainly used to increase the fluidity of the segregated flow solidified soil, so that the grouting pump can smoothly inject the segregated flow soil into the hole.

[0043] In addition, it should be noted that the clinker in the curing agent is Portland cement or fly ash cement of P.O42.5 or P.C42.5, and its specific surface area ≥ 380m 2 / kg. The slag powder is S95 grade slag powder, which is a mineral waste residue after high-temperature calcination, and its specific surface area ≥ 400m 2 / kg, with relatively high activity. The particle size of the stone powder residue is less than 0.5mm. The stone powder residue is specifically the powder waste residue of a quarry, referring to the powdery particles with a particle size less than 0.075mm remaining after the quarry uses block stones to crush and produce medium and coarse sand aggregates. Since the stone powder residue particles are relatively fine, they can fill the pores in the segregated flow solidified soil, make the soil structure more dense, thereby reducing the porosity, improving the compactness of the soil, and enhancing the plugging effect. In addition, the presence of the stone powder residue can increase the friction between the particles of the segregated flow solidified soil, make the soil more stable during the curing process, not easily deformed and displaced, and contribute to maintaining the stability of the plugging.

[0044] As a second aspect, the present invention also provides a preparation method of the segregated flow solidified soil, and this preparation method is used to prepare the above-mentioned segregated flow solidified soil. Specifically, it includes the following steps:

[0045] S1: Immerse the muck in water to obtain a muck immersion solution. In the muck immersion solution, the mass ratio of muck to water is 1:(0.8 to 1). It should be noted that the muck in the present invention is derived from the on-site soil or the engineering muck to be used. Before immersing the muck, the water content in the muck should be detected to make it between 20% and 30%. If the water content is too high and the muck agglomerates, appropriate drying should be carried out to reduce the soil water content. Then, the site soil is crushed using a crushing bucket, and the crushed small particle muck is screened using a screening machine to remove particles with a particle size greater than 1 mm. The screened muck is then immersed in water.

[0046] S2: Mix the solidifying agent powder and water evenly to prepare a solidifying agent slurry. Among them, the solidifying agent powder is a mixture of its various component powders according to the ratio, and the mass ratio of muck to the solidifying agent powder is 1:(0.2 to 0.25). In addition, in the solidifying agent slurry, the mass ratio of the solidifying agent powder to water is 1:(1.5 to 3). In specific preparation, the total mass of the solidifying agent powder required for each ton of muck should be calculated first, and then the water consumption for preparing the solidifying agent slurry should be calculated according to the mass of the required solidifying agent powder.

[0047] S3: Mix the solidifying agent slurry with the muck immersion solution and stir to obtain a fluidized solidified soil. Specifically, the muck immersion solution and the solidifying agent slurry are simultaneously added into a stirring bucket for stirring, and the stirring time is kept not less than 10 min to ensure that the fluidized solidified soil is stirred evenly.

[0048] In a third aspect, the present invention also relates to the application of the above fluidized solidified soil in plugging boreholes. Figure 2Schematic diagram of injecting fluidized solidified soil into an exploration borehole in an exemplary embodiment of the present invention. In the figure, 1 is the fluidized solidified soil, 2 is the exploration borehole, 3 is the cohesive soil layer, and 4 is the confined aquifer. Specifically, in practical applications, the following steps may be included: First, start the water pump. While injecting water, the drill bit drills downward along the original exploration borehole 2 until it reaches the bottom of the original exploration borehole 2. Then, continue to start the water pump, and the water pump injects tap water into the bottom of the hole through the drill pipe of the drilling rig. During the upward return of the clear water in the borehole, the sediment in the hole is continuously returned out of the hole. Then, turn off the water pump, connect the top of the drill pipe of the drilling rig to the mortar pump, start the mortar pump to inject the fluidized solidified soil 1 into the bottom of the exploration borehole 2, and lift the drill pipe while injecting the fluidized solidified soil 1. During the lifting process, it is necessary to ensure that the bottom drill bit is always located no less than 2 m below the top surface of the fluidized solidified soil 1. During the upward return of the fluidized soil in the hole, the accumulated water in the hole is continuously pushed upward and then returned out of the hole. Finally, the entire hole is completely filled and compacted with the fluidized soil. When the fluidized solidified soil 1 returns out of the hole opening, slowly lift the drill pipe and move the drilling rig to the next hole opening for the construction of injecting fluidized solidified soil into the hole. The fluidized solidified soil in the embodiment of the present invention can solidify after 24 h, and the interface shear strength can reach more than 3.0 MPa after 7 days. At this time, the foundation pit excavation work can be further carried out.

[0049] The present invention will be described in detail below through specific examples and comparative examples:

[0050] Example 1

[0051] In this specific example, the site soil is selected as the muck, and the water content in the muck is controlled to be 20% to 30%. After screening, the muck is soaked in water to obtain the muck soaking solution, and the mass ratio of the muck to water is 1:0.9.

[0052] The curing agent powder and water are mixed evenly to prepare the curing agent slurry. Among them, the curing agent powder includes the following components in parts by weight: Portland cement clinker: 20 parts, granulated blast-furnace slag powder: 25 parts, fly ash: 15 parts, waste gypsum: 15 parts, stone powder slag: 20 parts, anti-dispersant: 3 parts, water reducer: 2 parts. The mass ratio of the muck to the curing agent powder is 1:0.2. In the curing agent slurry, the mass ratio of the curing agent powder to water is 1:2.6.

[0053] In this specific example, the Portland cement clinker is P.O42.5 Portland cement, the granulated blast-furnace slag powder is S95 grade granulated blast-furnace slag powder, the fly ash is grade I fly ash with a calcium oxide content of 10%, the waste gypsum is desulfurized gypsum, and the anti-dispersant is polyacrylamide.

[0054] The curing agent slurry and the muck soaking solution are mixed and stirred to obtain the fluidized solidified soil.

[0055] Example 2

[0056] The difference between this embodiment and Embodiment 1 lies in the muck immersion liquid, where the mass ratio of muck to water is 1:0.96, and the mass ratio of muck to the solidifying agent powder is 1:0.25. In the solidifying agent slurry, the mass ratio of the solidifying agent powder to water is 1:1.96. The types and preparation methods of the components of the solidifying agent are the same.

[0057] Comparative Example

[0058] In this comparative example, cement slurry is used as the plugging agent for the exploration borehole.

[0059] Effect Example

[0060] The interfacial shear strength data of the fluidized solidified soil in Embodiment 1 and Embodiment 2 and the cement slurry in the comparative example are detected respectively, and the detection results are shown in Table 1:

[0061] Table 1 Variation data of the interfacial shear strength of the fluidized solidified soil in Embodiment 1 and Embodiment 2

[0062]

[0063] As can be seen from Table 1, compared with the traditional cement slurry, the interfacial shear strength of the fluidized solidified soil in the embodiments of the present invention gradually increases within 28 days after preparation, and the interfacial shear strength can reach more than 3.0 MPa after 7 days.

[0064] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A fluid-solidified soil, characterized in that, By mass percentage, the fluidized solidified soil comprises 50% to 60% of muck, 35% to 40% of water and 5% to 13% of solidifying agent; Among them, the solidifying agent comprises the following components in parts by weight: clinker: 5 parts to 25 parts, slag powder: 25 parts to 50 parts, fly ash: 10 parts to 25 parts, waste gypsum: 10 parts to 20 parts, stone powder residue: 10 parts to 20 parts, anti-dispersant: 1 part to 3 parts, water reducing agent: 1 part to 5 parts.

2. The flowable solidified soil according to claim 1, characterized in that, In the solidifying agent, by mass percentage, the calcium oxide content in the fly ash is 5% to 10%.

3. The flowable solidified soil according to claim 1, wherein In the solidifying agent, the waste gypsum is desulfurized gypsum and / or phosphogypsum.

4. The flowable solidified soil according to claim 1, characterized in that, In the solidifying agent, the particle size of the stone powder residue is less than 0.5 mm.

5. The flowable solidified soil according to claim 1, characterized in that, In the solidifying agent, the component of the anti-dispersant includes polyacrylamide.

6. The flowable solidified soil according to claim 1, wherein In the solidifying agent, the water reducing agent is naphthalene sulfonate formaldehyde condensate.

7. The flowable solidified soil according to claim 1, wherein The particle size of the muck is less than or equal to 1 mm.

8. A preparation method of fluid-solidified soil, characterized in that, Comprising: Soaking the muck in water to obtain a muck soaking solution; Mixing the solidifying agent powder and water evenly to prepare a solidifying agent slurry; Mixing the solidifying agent slurry with the muck soaking solution and stirring to obtain the fluidized solidified soil.

9. The preparation method of the fluidized solidified soil according to claim 8, wherein, In the muck soaking solution, the mass ratio of muck to water is 1:(0.8 to 1); And / or, the mass ratio of the muck to the solidifying agent powder is 1:(0.2 to 0.25); And / or, in the solidifying agent slurry, the mass ratio of the solidifying agent powder to water is 1:(1.5 to 3).

10. Application of the fluidized solidified soil according to any one of claims 1 to 7 in plugging boreholes.

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