A high gravity high strength improved soil based on barite powder and a method of making the same

Abstract

The application relates to the field of soil materials, and aims to provide a high-density high-strength improved soil based on barite powder and a preparation method thereof.A high-density high-strength improved soil based on barite powder comprises undisturbed soil material, barite powder, cement and additional water, the weight ratio of the undisturbed soil material, the barite powder and the cement is 1:(0.2-0.8):(0.1-0.2), the weight ratio of the cement and the additional water is 1:(0.4-0.6), wherein the particle density of the barite powder is 3.0 g / cm 3 -4.0 g / cm 3 , and the particle size of the barite powder is 0.075 mm-0.15 mm.The undisturbed soil body is improved by the waste barite powder, the mechanical properties of the undisturbed soil body are effectively improved, and good economic benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of soil materials, specifically to a high-density, high-strength improved soil based on barite powder and its preparation method. Background Technology

[0002] With the rapid development of my country's economy and the accelerated development of urban underground space, deep foundation pit projects in coastal soft soil areas are increasing. Thick layers of silty soft soil are widely distributed in the Quaternary system along the coast, characterized by high water content, high compressibility, and low strength. The design of foundation pit support directly affects project safety and cost. Currently, pile bracing and pile anchor support are commonly used, with internal bracing being the most widely applied. However, traditional cast-in-place concrete supports suffer from problems such as long construction periods, the need for dismantling, uneconomical practices, and environmental unfriendliness, which are inconsistent with the green and low-carbon concept.

[0003] Traditional designs often focus on resisting active earth pressure on the outside of the foundation pit, relying excessively on internal supports to provide lateral stiffness. From a green, economic, and safety perspective, the design approach should be shifted to strengthen the soft soil in the passive zone of the foundation pit, increasing its density, shear strength, and deformation performance to enhance the pit's stability. Combined with prefabricated steel supports, internal supports can be reduced or even eliminated while ensuring safety, thereby achieving the goals of shortening the construction period, reducing costs, and saving energy and reducing carbon emissions.

[0004] Currently, passive zone reinforcement of foundation pits mainly involves adding binding materials to the undisturbed soil and performing composite mixing. This process uses cement and other binding materials to mix with in-situ silt to form improved soil, thereby increasing the soil's shear strength. However, traditional methods only focus on improving shear strength and neglect the effect of soil weight on foundation pit stability. Furthermore, the binding materials are mostly cement, fly ash, and slag, which have limited effect on increasing soil weight. At the same time, the silt widely distributed in southeastern coastal areas has undesirable engineering characteristics such as high water content, high void ratio, low strength, and high compressibility. Traditional methods are insufficient to meet the engineering requirements for deep foundation pit support when modifying this type of silt.

[0005] Barite powder, whose main component is BaSO4, is chemically stable and has a high density. In industrial production, barite powder is often sold as a drilling lubricant, but its density is required to be ≥4.0 g / cm³. 3 However, large quantities of unsuitable barite powder are discarded, resulting in resource waste and environmental burden. Furthermore, current research on barite powder has not yet extended to soil reinforcement; research on using barite powder to improve soil properties has enormous market potential and broad application prospects. Therefore, developing a technology for preparing high-density, high-strength improved soil using barite powder, which addresses the technical shortcomings of traditional foundation pit reinforcement methods and enables the resource utilization of barite powder, has become an urgent technical problem to be solved in the field of geotechnical engineering. Summary of the Invention

[0006] One of the objectives of this invention is to provide a high-density, high-strength modified soil based on barite powder. By using waste barite powder to improve the original soil, the mechanical properties of the original soil are effectively improved, resulting in good economic benefits.

[0007] One of the objectives of this invention is achieved through the following technical solution: A high-density, high-strength improved soil based on barite powder comprises undisturbed soil material, barite powder, cement, and added water. The weight ratio of the undisturbed soil material, barite powder, and cement is 1:(0.2-0.8):(0.1-0.2); the weight ratio of cement to added water is 1:(0.4-0.6); wherein the particle density of the barite powder is 3.0 g / cm³. 3 -4.0g / cm 3 The barite powder has a particle size of 0.075mm-0.15mm.

[0008] The second objective of this invention is to provide a method for preparing high-density, high-strength modified soil based on barite powder, which is achieved through the following technical solution: A method for preparing high-density, high-strength modified soil based on barite powder includes the following steps: S1. Weigh the original soil material, barite powder, cement and added water according to the design ratio, and pour the original soil material, barite powder, cement and added water into the mixer for mixing to form a uniform modified soil slurry. S2. Fill the mold with the improved soil slurry, then fix the mold on the vibrating table to compact it. After compaction, scrape off the excess improved soil slurry on the surface. S3. Cover the mold with plastic film and place the mold and the modified soil slurry inside in a standard curing room for 48 hours. S4. After 48 hours, the mold is removed, and the improved soil is placed in water for curing. After curing for the specified age, it is taken out to obtain high density and high strength improved soil.

[0009] Compared with the prior art, the advantages of the present invention are as follows: 1. Compared to methods that only use cement to improve the original soil material, this invention incorporates barite powder into the original soil material. Without affecting the cement's curing effect, the high density and chemically stable properties of barite powder allow it to form a more stable skeleton structure with soil particles. Under the action of cement hydration, the barite powder further integrates into a whole, thereby effectively increasing the density and strength of the improved soil. This results in increased density, decreased moisture content, and reduced void ratio of the improved soil. At the same time, the unconfined compressive strength and shear strength are improved, which in turn helps to improve the resistance of the passive zone soil of the foundation pit, enhance the stability of the foundation pit, and reduce the deformation of the foundation pit.

[0010] 2. The barite powder used in this invention has a particle density of 3.0 g / cm³. 3 -4.0g / cm 3 Waste materials with a particle size of 0.075mm-0.15mm are inexpensive and have limited disposal and utilization methods. This invention applies them to the preparation of improved soil, which can not only improve the physical and mechanical properties of the original soil and make up for the shortcomings of traditional improved soil in terms of limited increase in density and insufficient improvement in strength, but also realize the resource utilization of waste barite powder, thereby reducing engineering costs and reducing environmental pollution, and has good economic benefits and application value. Detailed Implementation

[0011] The present invention will be described in detail below with reference to embodiments: A high-density, high-strength improved soil based on barite powder comprises undisturbed soil material, barite powder, cement, and added water. The weight ratio of the undisturbed soil material, barite powder, and cement is 1:(0.2-0.8):(0.1-0.2); the weight ratio of cement to added water is 1:(0.4-0.6); wherein the particle density of the barite powder is 3.0 g / cm³. 3 -4.0g / cm 3 The barite powder has a particle size of 0.075mm-0.15mm.

[0012] Preferably, the weight ratio of the undisturbed soil, barite powder, and cement is 1:(0.4-0.8):0.1, and the weight ratio of cement to added water is 1:0.5. More preferably, the weight ratio of the undisturbed soil, barite powder, and cement is 1:0.8:0.1.

[0013] Preferably, the barite powder has a particle density of 3.5 g / cm³. 3 .

[0014] Preferably, the cement is PO42.5 grade ordinary Portland cement.

[0015] Preferably, the original soil material is silty soil.

[0016] A method for preparing high-density, high-strength modified soil based on barite powder includes the following steps: S1. Weigh the original soil material, barite powder, cement and added water according to the design ratio, and pour the original soil material, barite powder, cement and added water into the mixer for mixing to form a uniform modified soil slurry. S2. Fill the mold with the improved soil slurry, then fix the mold on the vibrating table and vibrate it for 2-3 minutes. After vibration, scrape off the excess improved soil slurry on the surface. S3. Cover the mold with a plastic film and place the mold and the modified soil slurry inside it in a standard curing room for 48 hours. It should be noted that a standard curing room refers to a curing environment with a temperature of 20±2℃ and a relative humidity of ≥95%. S4. After 48 hours, the mold is removed, and the improved soil is placed in water for curing. After curing for the specified age, it is taken out to obtain high density and high strength improved soil.

[0017] Further, in step S1, the original soil material is weighed and its weight is recorded, and then the corresponding amount of barite powder, cement and added water are weighed according to the weight of the original soil material. The original soil material is dried, crushed, and sieved with a mesh size of 5mm to obtain dry fine soil material. The weight of water loss of the original soil material is determined based on the weight of the original soil material and the weight of the dry fine soil material. Mix the dry fine soil with the weighed barite powder and cement and dry mix for 3-5 minutes to make the dry fine soil, barite powder and cement evenly mixed to obtain the improved soil powder. Add the recovery water, which is equivalent to the weight of the original soil material in terms of water loss, and the added water together to the improved soil powder and stir for 10-20 minutes to obtain a uniform improved soil slurry.

[0018] Furthermore, in step S2, the improved soil slurry is filled into the mold in three batches, and is vibrated 15-30 times after each filling.

[0019] Furthermore, in step S4, the demolded improved soil is placed in water at a temperature of 20±1℃ for curing, and the water level is not less than 20mm above the surface of the improved soil.

[0020] To further illustrate the effect of a high-density, high-strength improved soil based on barite powder, the following table provides a detailed explanation: 1. Material selection: The original soil material was selected from silt from a construction project site in Fuzhou, with a sampling depth ranging from 2m to 5m and a density of 1.608g / cm³. 3 The moisture content is 55.60%, the porosity is 1.526, the cohesion is 7.6 kPa, and the internal friction angle is 1.8°. The barite powder selected has a particle density of 3.5 g / cm³. 3 The particle size is 0.075mm-0.15mm; The cement is PO42.5 grade ordinary Portland cement.

[0021] 2. Setup of the comparative and implementation examples: In the comparative example, the weight ratio of undisturbed soil, barite powder, and cement was 1:0:0.1, and the weight ratio of cement to added water was 1:0.5. In Example 1, the weight ratio of raw soil, barite powder, and cement is 1:0.2:0.1, and the weight ratio of cement to added water is 1:0.5. In Example 2, the weight ratio of raw soil, barite powder, and cement is 1:0.4:0.1, and the weight ratio of cement to added water is 1:0.5. In Example 3, the weight ratio of raw soil, barite powder, and cement is 1:0.6:0.1, and the weight ratio of cement to added water is 1:0.5. In Example 4, the weight ratio of raw soil, barite powder, and cement is 1:0.8:0.1, and the weight ratio of cement to added water is 1:0.5.

[0022] The above comparative examples and all embodiments were prepared using the same preparation process, the specific preparation process of which is as follows: First, weigh the original soil material and record its weight. Then, weigh the corresponding amount of barite powder, cement, and added water according to the weight of the original soil material. Dry, crush, and sieve the original soil material to obtain dry fine soil material. Determine the weight of water loss of the original soil material based on the weight of the original soil material and the weight of the dry fine soil material. Then, mix the dry fine soil material with the weighed barite powder (except for the control example) and cement and dry-mix evenly to obtain improved soil powder. Subsequently, add the recovery water corresponding to the weight of water loss of the original soil material and the added water to the improved soil powder and stir to obtain a uniform improved soil slurry.

[0023] The modified soil slurry was filled into a 70.7mm×70.7mm×70.7mm mold in three batches, and vibrated 15-30 times after each filling. The mold was then fixed on a vibrating table and vibrated for 2-3 minutes. After compaction, excess modified soil slurry on the surface was scraped off. A plastic film was then placed over the mold, and the mold and the modified soil slurry inside were placed in a standard curing room for 48 hours. The standard curing room was a curing environment with a temperature of 20±2℃ and a relative humidity of ≥95%. After 48 hours, the mold was removed, and the modified soil was placed in water for curing until the specified age was reached. The resulting test blocks were the control example and Examples 1-4.

[0024]

[0025] Table 1 shows that with the addition of barite powder, the density of the improved soil gradually increases, the moisture content gradually decreases, and the void ratio gradually decreases, indicating that the addition of barite powder can effectively improve the internal skeletal structure of the soil and increase its compactness. Simultaneously, with the increase of barite powder content, the unconfined compressive strength and shear strength of the improved soil both increase, indicating that the addition of barite powder can enhance the friction and interlocking between soil particles, thereby improving the overall mechanical properties of the improved soil.

[0026] In summary, the high density and high strength modified soil based on barite powder provided by this invention has a significant improvement effect on physical and mechanical properties when the barite powder content is 40%-80% of the original soil weight. It has good engineering application value and is especially suitable for the reinforcement of the passive zone of deep foundation pits. It can effectively improve the stability of foundation pits and reduce foundation pit deformation.

[0027] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-density, high-strength improved soil based on barite powder, characterized in that: The mixture comprises raw soil, barite powder, cement, and added water. The weight ratio of the raw soil, barite powder, and cement is 1:(0.2-0.8):(0.1-0.2); the weight ratio of cement to added water is 1:(0.4-0.6); and the particle density of the barite powder is 3.0 g / cm³. 3 -4.0g / cm 3 The barite powder has a particle size of 0.075mm-0.15mm.

2. The high-density, high-strength improved soil based on barite powder according to claim 1, characterized in that: The weight ratio of the original soil, barite powder, and cement is 1:(0.4-0.8):0.1, and the weight ratio of cement to added water is 1:0.

5.

3. The high-density, high-strength improved soil based on barite powder according to claim 2, characterized in that: The weight ratio of the original soil, barite powder, and cement is 1:0.8:0.

1.

4. The high-density, high-strength improved soil based on barite powder according to any one of claims 1 to 3, characterized in that: The particle density of the barite powder is 3.5 g / cm³. 3 .

5. The high-density, high-strength improved soil based on barite powder according to claim 4, characterized in that: The cement is PO42.5 grade ordinary Portland cement.

6. The high-density, high-strength improved soil based on barite powder according to claim 4, characterized in that: The original soil material is silty soil.

7. A method for preparing high-density, high-strength improved soil based on barite powder as described in claim 1, characterized in that, Includes the following steps: S1. Weigh the original soil material, barite powder, cement and added water according to the design ratio, and pour the original soil material, barite powder, cement and added water into the mixer for mixing to form a uniform modified soil slurry. S2. Fill the mold with the improved soil slurry, then fix the mold on the vibrating table to compact it. After compaction, scrape off the excess improved soil slurry on the surface. S3. Cover the mold with plastic film and place the mold and the modified soil slurry inside in a standard curing room for 48 hours. S4. After 48 hours, the mold is removed, and the improved soil is placed in water for curing. After curing for the specified age, it is taken out to obtain high density and high strength improved soil.

8. The method for preparing high-density, high-strength improved soil based on barite powder according to claim 7, characterized in that: In step S1, first weigh the original soil material and record its weight, then weigh the corresponding amount of barite powder, cement and added water according to the weight of the original soil material. The original soil material is dried, crushed and sieved to obtain dry fine soil material, and the weight of water loss of the original soil material is determined based on the weight of the original soil material and the weight of the dry fine soil material. Mix the dry fine soil with the weighed barite powder and cement, and dry mix evenly to obtain the improved soil powder. Add restoring water equivalent to the weight of the original soil material after water loss, along with additional water, to the improved soil powder and stir to obtain a uniform improved soil slurry.

9. The method for preparing high-density, high-strength improved soil based on barite powder according to claim 7, characterized in that: In step S2, the modified soil slurry is filled into the mold in three batches, and is vibrated after each filling.

10. The method for preparing high-density, high-strength improved soil based on barite powder according to claim 7, characterized in that: In step S4, the demolded improved soil is placed in water at a temperature of 20±1℃ for curing, and the water level is not less than 20mm above the surface of the improved soil.

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