A reinforced pile of constrained solidified soil with high efficient utilization of expansion energy of solidifying agent

Abstract

In order to solve the technical problem of low utilization efficiency of curing agent expansion energy in the constrained curing technology, the application discloses a constrained curing soil reinforced pile with high efficient utilization of curing agent expansion energy and belongs to the field of traffic engineering, which is characterized by the following steps: a material with slow hydration rate is used as the cementing component of the curing agent, and the cementing hydrates generated by the hydration of the material include but are not limited to hydrated calcium silicate, hydrated calcium aluminate and hydrated calcium silico-aluminate; meanwhile, a material with rapid hydration expansion is used as the expansion component of the curing agent, and the expansion hydrates generated by the hydration of the material include but are not limited to ettringite and single-sulfur calcium sulphoaluminate; the mass ratio of the cementing component and the expansion component in the curing agent is 25-80:20-75; the curing agent is mixed with the in-situ ground soil at a fixed water-cement ratio, and then the mixture is uniformly filled into the constrained pipe with good mechanical properties which has been implanted into the ground in advance and is extruded and compacted to form the constrained curing soil reinforced pile, so that the strength of the curing soil and the strength of the pile body of the constrained curing soil reinforced pile can be greatly improved.

Description

Technical Field

[0001] This invention relates to a confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent, belonging to the field of transportation engineering. Background Technology

[0002] The constrained solidification technology is a new method for soil reinforcement based on existing solidified soil piles. Specifically, the constrained solidification technology uses a solidifying agent containing an expansive component to organically combine with a constraining tube to produce multiple reinforcement effects: ① The volume expansion of the expansive component during hydration under constrained conditions can reduce the porosity of the solidified soil, thereby increasing the strength of the solidified soil; ② The bearing capacity of the solidified soil is greatly improved under the lateral constraint provided by the constraining body; ③ The volume expansion generated by the hydration of the expansive component under constrained conditions increases the overall stiffness, further improving the bearing capacity of the constrained solidified soil. For details, see the patents "Construction Method of Solidified Soil Pile" (ZL201610183422.6) and "Treatment Method of Contaminated Soil" (201610184702.9).

[0003] However, constrained soil reinforcement technology primarily uses silicate-based cements as binders, resulting in significant carbon emissions. Furthermore, with existing constrained reinforcement technologies, using binders and expanders with different hydration rates, even with constant content of binders and expanders in the curing agent, leads to significant differences in the strength of the resulting reinforced soil and the strength of the reinforced pile. This results in ineffective control of the curing agent's expansion energy and low utilization efficiency. These problems significantly restrict the widespread application of constrained soil reinforcement technology in foundation reinforcement.

[0004] Based on this, the present invention proposes a confined solidified soil reinforced pile that efficiently utilizes the expansion energy of the curing agent. Summary of the Invention

[0005] This invention proposes a confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of the curing agent. It can solve the problem of low utilization efficiency of the expansion energy of the curing agent in existing confined and solidified soil reinforced pile technology. By using industrial waste residue to completely replace silicate series cement as the binding material, it not only significantly reduces carbon emissions but also saves costs significantly. It can achieve the technical effect of greatly improving both the strength of the solidified soil and the strength of the confined and solidified soil reinforced pile.

[0006] This invention proposes a confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent. Specifically, it employs a material with a slow hydration rate as the cementing component of the curing agent, while simultaneously using a material with rapid hydration and expansion as the expansion component. The water-cement ratio of the curing agent is controlled, and in-situ foundation soil is used as the pile preparation material with controlled soil moisture content. The curing agent is mixed evenly with the in-situ foundation soil at a fixed water-cement ratio and near the optimum moisture content. This mixture is then filled into a pre-embedded confining tube with good mechanical properties, layered and compacted to form a confined and solidified soil reinforced pile. This method allows for full utilization of the curing agent's expansion energy and significantly increases its utilization efficiency. The allowable mass content of the expansion component in the curing agent is increased to 75%, resulting in a substantial increase in both the strength of the solidified soil and the strength of the confined and solidified soil reinforced pile.

[0007] The curing agent of this invention is composed of a cementing component and an expansion component, wherein the mass ratio of the cementing component to the expansion component in the curing agent is 25-80:20-75, respectively; the dosage of the curing agent is 10-100% of the total dry weight of the curing agent and the soil; all the constituent materials of the curing agent are industrial grade, and all the curing agent materials have a specific surface area greater than 200 m². 2 / kg of powder.

[0008] The cementing component of this invention is a material with a slow hydration rate, and the cementing hydrates produced by its hydration include, but are not limited to, hydrated calcium silicate, hydrated calcium aluminate, hydrated calcium aluminosilicate, etc.; the cementing component is composed of slag and an alkali activator, and the mass ratio of slag and alkali activator in the cementing component is 80~100:0~20, respectively; the alkali activator includes, but is not limited to, one or more combinations of quicklime, hydrated lime, activated magnesium oxide, carbide slag, sodium hydroxide, hydrated sodium silicate, etc.

[0009] The expansion component of this invention is a rapidly hydrating expansion type material, and the expansion hydrates produced by its hydration include, but are not limited to, ettringite, monosulfide calcium sulfoaluminate, etc.; the expansion component includes, but is not limited to, a mixture composed of aluminate cement, quicklime, and gypsum in a mass ratio ranging from 9 to 12: 6 to 8: 24 to 30.

[0010] The materials of the constraint tube of the present invention include, but are not limited to, rigid materials and flexible materials, as well as combinations of the two types of materials; the rigid materials include, but are not limited to, steel pipes, polyvinyl chloride pipes, polyethylene pipes, reinforced high-density polyethylene pipes, polybutene pipes, polypropylene pipes, fiber braided pultruded pipes, etc.; the flexible materials include, but are not limited to, fiber-reinforced composite fabrics, etc.; the ratio of the ultimate constraint stress provided by the constraint tube to the strength of the solidified soil is greater than 0.6.

[0011] The cementing component described in this invention requires the selection of an activator based on the hydration rate of the cementing component design, and the specific ratio of slag and alkali activator in the cementing component is determined through preliminary experiments.

[0012] The specific proportions of each component in the expansion component need to be determined according to the chemical equation for the formation of the expansion hydrate by hydration and according to known calculation methods.

[0013] The water-cement ratio control of the curing agent described in this invention refers to controlling the water-cement ratio according to the composition of the curing agent to meet the minimum water consumption required for all curing agent components to be fully hydrated.

[0014] The implanted foundation described in this invention uses a known method of drilling holes in the in-situ foundation; the layered extrusion compaction method includes, but is not limited to, heavy hammer compaction, static pressure equipment compaction, and reverse spiral pressing equipment compaction, and the construction parameters are determined through field tests.

[0015] The application scope of the constrained and solidified soil reinforced piles described in this invention includes, but is not limited to, airport engineering, road engineering, industrial building engineering, etc.

[0016] The construction process of the constrained and solidified soil reinforced pile described in this invention is as follows: First, conduct an engineering survey to understand the physical properties of the foundation soil; second, based on the design values ​​of the solidified soil strength and the pile body strength, determine the material composition of the cementing and expansion components in the curing agent, the dosage of the curing agent, and the material composition and dimensions of the constrained tube; third, implant the constrained tube into the foundation. When the constrained tube is a rigid tube, it is directly implanted into the foundation after installing the pile tip. When the constrained tube is a flexible tube, it needs to be implanted into the foundation with the help of a recyclable rigid sleeve; finally, mix the curing agent with the in-situ foundation soil at a fixed water-cement ratio, fill it into the constrained tube that has been pre-implanted into the foundation, and compact it in layers to form a constrained and solidified soil reinforced pile. When the curing age is reached, test the performance of the constrained and solidified soil reinforced pile.

[0017] The advantages of this invention are: 1. This invention uses a material with a slow hydration rate as the binding component and a material with a rapid hydration and expansion rate as the expansion component, which solves the technical problem that the expansion energy of the curing agent cannot be effectively controlled and the utilization efficiency is low in the existing constrained curing technology.

[0018] 2. Compared with existing confined soil reinforced pile technology, this invention makes full use of the curing agent expansion energy, achieving a technical effect of doubling the utilization efficiency of curing agent expansion energy, and increasing the allowable content of expansion component in the curing agent to 75%.

[0019] 3. This invention uses industrial waste residue to completely replace silicate cement as a binding material, which significantly reduces carbon emissions and saves costs, and achieves the effect of greatly improving the strength of the solidified soil and the strength of the pile body reinforced by the confined solidified soil. Detailed Implementation

[0020] The following detailed description of a confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent, as described in this invention, is based on specific embodiments. However, the application forms and scope of the optimized technology for confined and solidified soil reinforced piles provided by this invention are not limited to this.

[0021] Example 1 The foundation of a certain highway is reinforced using confined and solidified soil reinforced piles. According to the engineering survey report, the soil moisture content is 40%, and the soil particle size distribution (mass fraction) is: sand 10%, silt 40%, and clay 50%. The confined and solidified soil reinforced piles, which utilize the expansion energy of the solidifying agent as described in this invention, are used to treat the foundation, forming a confined and solidified soil reinforced pile composite foundation. The designed pile length is 6m, the pile diameter is 200mm, and the strength of the solidified soil and the strength of the confined and solidified soil reinforced pile body are 10MPa and 32MPa, respectively.

[0022] The curing agent, selected by weight, comprises the following components: 8.0 parts slag and 2.0 parts quicklime as the cementing component; and 7.4 parts aluminate cement, 4.4 parts quicklime, and 16.2 parts gypsum as the expanding component. The curing agent dosage is 25% of the total dry weight of the curing agent and soil, with a water-cement ratio of 0.42. A 6mm thick steel pipe is selected for the confinement tube and implanted into the foundation. The curing agent mixture is mixed evenly with the in-situ foundation soil at a fixed water-cement ratio and layered into the steel pipe. A field compaction test is conducted using a heavy hammer to determine the construction parameters. The solidified soil inside the steel pipe is compacted in layers to form a confined solidified soil reinforced pile. After pile quality testing, the strength of the solidified soil and the strength of the confined solidified soil reinforced pile after 28 days of curing both meet the requirements.

[0023] Example 2 The foundation of an airport project was reinforced using confined and solidified soil-reinforced piles. According to the engineering survey report, the soil moisture content was 15%, and the soil particle size distribution (mass fraction) was: 30% sand, 30% silt, and 40% clay. The project employed a confined and solidified soil-reinforced pile, as described in this invention, which efficiently utilizes the expansion energy of the solidifying agent, to form a confined and solidified soil-reinforced pile composite foundation. The designed pile length was 18m, the pile diameter was 300mm, and the strength of the solidified soil and the strength of the confined and solidified soil-reinforced pile body were 16MPa and 45MPa, respectively.

[0024] The curing agent, selected by weight, comprises the following components: 8.5 parts slag and 1.5 parts carbide slag as the cementing component; and 1.8 parts aluminate cement, 1.2 parts quicklime, and 4.5 parts gypsum as the expanding component. The curing agent dosage is 40% of the total dry weight of the curing agent and soil, with a water-cement ratio of 0.48. A 10mm thick GFRP pipe is selected as the confinement tube and implanted into the foundation. The curing agent mixture is mixed evenly with the in-situ foundation soil at a fixed water-cement ratio and layered into the GFRP pipe. A static compaction test is conducted on-site to determine construction parameters. The solidified soil inside the GFRP pipe is compacted in layers to form a confined solidified soil-reinforced pile. After pile quality testing, both the strength of the solidified soil and the strength of the confined solidified soil-reinforced pile after 28 days of curing meet the requirements.

[0025] Example 3 The foundation of a high-speed railway is reinforced using confined and solidified soil-reinforced piles. According to the engineering survey report, the soil moisture content is 35%, and the soil particle size distribution (mass fraction) is: sand 20%, silt 50%, and clay 30%. A confined and solidified soil-reinforced pile, utilizing the expansion energy of the curing agent as described in this invention, is used to treat the foundation, forming a confined and solidified soil-reinforced pile composite foundation. The designed pile length is 14m, the pile diameter is 250mm, and the strength of the solidified soil and the strength of the confined and solidified soil-reinforced pile body are 23MPa and 58MPa, respectively.

[0026] The curing agent, selected by weight, comprises the following components: 9.0 parts slag and 1.0 part hydrated sodium silicate as the cementing component; and 1.0 part aluminate cement, 0.7 parts quicklime, and 2.3 parts gypsum as the expanding component. The curing agent dosage is 55% of the total dry weight of the curing agent and soil, with a water-cement ratio of 0.38. Twelve layers of CFRP fabric are selected as the confinement tubes, which are then implanted into the foundation using rigid sleeves. The curing agent mixture is mixed evenly with the in-situ foundation soil at a fixed water-cement ratio and layered into the confinement tubes. A reverse-auger compaction test is conducted on-site to determine construction parameters. The solidified soil within the confinement tubes is compacted layer by layer to form confinement-solidified soil-reinforced piles. After construction, the rigid sleeves are retrieved. Pile quality testing shows that the strength of the solidified soil and the strength of the confinement-solidified soil-reinforced piles after 28 days of curing both meet the requirements.

[0027] Example 4 The foundation of an industrial building was reinforced using confined and solidified soil-reinforced piles. According to the engineering survey report, the soil moisture content was 19%, and the soil particle size distribution (mass fraction) was: sand 25%, silt 45%, and clay 30%. The foundation was treated with confined and solidified soil-reinforced piles, which utilize the expansion energy of the solidifying agent as described in this invention, forming a confined and solidified soil-reinforced pile composite foundation. The designed pile length was 10m, the pile diameter was 150mm, and the strength of the solidified soil and the strength of the confined and solidified soil-reinforced pile body were 30MPa and 68MPa, respectively.

[0028] The curing agent, selected by weight, comprises the following components: 8.0 parts slag and 2.0 parts quicklime as the cementing component; and 2.5 parts aluminate cement, 1.5 parts hydrated lime, and 6.2 parts gypsum as the expanding component. The curing agent dosage is 70% of the total dry weight of the curing agent and soil, with a water-cement ratio of 0.5. A 10mm thick PE pipe with six layers of AFRP fabric is selected as the confinement pipe and implanted into the foundation. The curing agent mixture is mixed evenly with the in-situ foundation soil at a fixed water-cement ratio and layered into the confinement pipe. A static compaction test is conducted on-site to determine construction parameters. The solidified soil inside the confinement pipe is compacted layer by layer to form a confinement-solidified soil-reinforced pile. After pile quality testing, the strength of the solidified soil and the strength of the confinement-solidified soil-reinforced pile after 28 days of curing both meet the requirements.

Claims

1. A confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent, characterized in that: The curing agent consists of a cementing component and an expansion component. A material with a slow hydration rate is used as the cementing component, while a material with rapid hydration and expansion is used as the expansion component. The cementing component is a material with a slow hydration rate, and the cementitious hydrates produced by its hydration include, but are not limited to, hydrated calcium silicate, hydrated calcium aluminate, and hydrated calcium aluminosilicate. The expansion component is a material with rapid hydration and expansion, and the expanding hydrates produced by its hydration include, but are not limited to, ettringite and monosulfide calcium aluminate. The water-cement ratio of the curing agent is controlled, and in-situ foundation soil is used. As a material for pile preparation, the curing agent dosage is 10-70% of the total dry weight of the curing agent and soil. The curing agent is mixed evenly with the in-situ foundation soil at a fixed water-cement ratio, filled into a pre-embedded, mechanically sound confinement tube, and compacted in layers to form a confinement-reinforced soil pile. This achieves a significant increase in the utilization efficiency of the curing agent's expansion energy, as well as a substantial increase in both the strength of the solidified soil and the pile body strength. The ratio of the ultimate confinement stress provided by the confinement tube to the strength of the solidified soil is greater than 0.

6. The specific characteristics of the curing agent are as follows: The mass ratio of the cementing component and the expanding component in the curing agent is 25-80:20-75, respectively; the cementing component is composed of slag and an alkali activator, with the mass ratio of slag and alkali activator in the cementing component being 80-100:0-20, respectively; the alkali activator includes, but is not limited to, one or more combinations of quicklime, hydrated lime, activated magnesium oxide, carbide slag, sodium hydroxide, and hydrated sodium silicate; the expanding component includes, but is not limited to, a mixture composed of aluminate cement, hydrated lime, and gypsum in a mass ratio ranging from 9-12:6-8:24-30; all components of the curing agent are industrial grade, and all curing agent materials have a specific surface area greater than 200 m². 2 / kg of powder.

2. The confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of the curing agent according to claim 1, characterized in that: The materials of the constraint tube include, but are not limited to, rigid materials and flexible materials, as well as combinations of the two types of materials. The rigid materials include, but are not limited to, steel pipes, polyvinyl chloride pipes, polyethylene pipes, reinforced high-density polyethylene pipes, polybutene pipes, polypropylene pipes, fiber braided pultruded pipes, etc., and the flexible materials include, but are not limited to, fiber-reinforced composite fabrics, etc.

3. The confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of the curing agent according to claim 1, characterized in that: The cementing component needs to select an activator based on the designed hydration rate of the cementing component, and determine the specific ratio of slag and alkali activator in the cementing component through preliminary experiments.

4. A confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent according to claim 1, characterized in that: The specific proportions of each component in the expansion component need to be determined according to the chemical equation for the formation of the expansion hydrate and the known calculation method.

5. A confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent according to claim 1, characterized in that: The aforementioned control of the water-cement ratio of the curing agent refers to controlling the water-cement ratio according to the composition of the curing agent to meet the minimum water consumption required for all curing agent materials to complete hydration.

6. A confined and solidified soil reinforced pile that efficiently utilizes the expansion energy of a curing agent according to claim 1, characterized in that: The application scope of the constrained and solidified soil reinforced piles includes, but is not limited to, airport engineering, road engineering, and industrial building engineering. The construction process of the constrained and solidified soil reinforced piles is as follows: ① Conduct engineering surveys to understand the physical properties of the foundation soil; ② Determine the material composition of the cementing and expansion components in the curing agent, the dosage of the curing agent, and the material composition and dimensions of the constraining tube based on the design values ​​of the solidified soil strength and the pile body strength of the constrained and solidified soil reinforced pile; ③ Insert the constraining tube into the foundation. When the constraining tube is a rigid tube, it is directly inserted into the foundation after installing the pile tip. When the constraining tube is a flexible tube, it needs to be inserted into the foundation with the help of a recyclable rigid sleeve; ④ Mix the curing agent with the in-situ foundation soil at a fixed water-cement ratio, fill it into the constraining tube that has been pre-inserted into the foundation, and compact it in layers to form a constrained and solidified soil reinforced pile. Test the performance of the constrained and solidified soil reinforced pile when it reaches the curing age.