In-situ solidification construction method for soft ground adjacent to embankment

Abstract

The application discloses a construction method of in-situ solidification of soft soil foundation adjacent to embankment, comprising the following steps: S1: construction preparation, surveying, clearing and site leveling of the solidification area; S2: area division, dividing the treatment area into multiple continuous construction blocks; S3: stirring and solidification, using excavating equipment with stirring head to perform sinking stirring and lifting stirring in the construction block, and synchronously spraying solidifying agent slurry; S4: leveling and curing, leveling and covering curing of the solidified soil body; when the treatment area is adjacent to the embankment slope, the construction block located at the slope toe is constructed in step S3 according to the jump warehouse sequence: before the stirring operation of any target block starts, the soil body of the target block is excavated; and the construction blocks arranged continuously along the longitudinal direction of the slope are sequentially constructed according to the sequence of interval of one or more blocks; the application significantly improves the bearing capacity and stability of the soft soil foundation, and effectively reduces the interference and damage to the surrounding environment.

Description

Technical Field

[0001] This invention relates to the field of road construction technology, and in particular to an in-situ consolidation method for soft soil foundations adjacent to embankments. Background Technology

[0002] In the booming development of transportation infrastructure construction, embankment engineering, as a vital link connecting cities and rural areas and promoting regional economic development, is particularly crucial in terms of safety and stability. However, in the treatment of soft soil foundations adjacent to embankments, traditional methods often struggle to balance the dual requirements of treatment effectiveness and environmental protection. Due to its unique physical and mechanical properties, such as high water content, high compressibility, and low shear strength, soft soil is prone to engineering problems such as embankment settlement and slippage during treatment, seriously threatening the safe use of embankments. Furthermore, traditional treatment methods often involve large-scale earthwork excavation and backfilling, resulting in long construction periods, high costs, and severe environmental disturbances and damage, such as dust pollution and soil erosion.

[0003] Specifically, the soft soil foundation treatment methods disclosed in Chinese patents with application numbers CN201510302548 and CN202010865754, while improving the bearing capacity of the foundation to some extent, still cannot avoid negative impacts on the surrounding environment during the treatment process. The former, through the combination of on-site solidification of surface soil and pile bearing, reduces some earthwork excavation, but still requires the laying of auxiliary materials such as sand and gravel cushion layers, increasing construction costs and environmental pollution risks; the latter, through an improved method of surface soil solidification and pile bearing, attempts to limit the tilting of the piles under the action of foundation pressure, but when treating large areas of soft soil foundations, it is still difficult to avoid disturbance to the surrounding ecological environment.

[0004] To address the aforementioned issues, this invention proposes a novel in-situ consolidation method for soft soil foundations adjacent to embankments. This method achieves precise treatment of the soft soil foundation, reducing its impact on slope stability. It ensures a dual optimization of treatment effectiveness and cost control. Furthermore, it significantly improves the bearing capacity and stability of the soft soil foundation while effectively reducing interference and damage to the surrounding environment. Summary of the Invention

[0005] This invention provides a method for in-situ consolidation of soft soil foundation adjacent to an embankment, comprising the following steps: S1: Construction preparation, including surveying, clearing and leveling the area to be solidified; S2: Area division, which divides the processing area into multiple consecutive construction blocks; S3: Mixing and curing. Excavation equipment equipped with a mixing head is used to carry out sinking and lifting mixing in the construction block, and the curing agent slurry is sprayed in simultaneously. S4: Leveling and curing, leveling and covering the solidified soil for curing; When the treatment area is adjacent to the embankment slope, in step S3, the construction blocks located at the toe of the slope are constructed in a skip-building sequence: before the mixing operation of any target block begins, the soil of the target block is excavated; and the construction blocks arranged continuously along the longitudinal direction of the slope are constructed in sequence with one or more blocks spaced apart.

[0006] Preferably, in step S3, the construction sequence is as follows: along the longitudinal direction of the slope, first construct all construction blocks with odd numbers, then construct all construction blocks with even numbers; or, first construct all construction blocks with even numbers, then construct all construction blocks with odd numbers.

[0007] Preferably, after the mixing head is lowered to the design elevation, its lifting speed is controlled between 15 and 20 seconds per meter within 0.5 meters above the pile bottom.

[0008] Preferably, in step S1, if a hard shell layer exists on the site, the hard shell layer of the corresponding construction block is pre-loosened using excavation equipment before mixing and solidification.

[0009] Preferably, in step S3, the curing agent slurry is a cement slurry, and the amount of cement added is dynamically adjusted according to the test results of the moisture content and wet density of the soil sample on site. The addition ratio ranges from 4% to 6% of the weight of the soil to be cured.

[0010] Preferably, before step S3, a supplementary exploration step is included: static penetration test holes are laid out along the longitudinal direction of the treatment area at intervals of 5 to 20 meters, and the solidification treatment depth and range of each construction block are finally determined based on the penetration test results.

[0011] Preferably, in step S3, the stirring head is a three-dimensional stirring head with a rotation speed of 50 to 120 revolutions per minute, and the verticality deviation of the stirring head connecting rod is no more than 2%.

[0012] Preferably, step S1 also includes a safe deployment step for the cement storage tank: installing the cement storage tank next to the construction area, the cement storage tank being fixed by multiple guy ropes, each guy rope having an independent counterweight connected to its lower end, and an anti-overturning calculation being performed after installation.

[0013] Preferably, in step S4, leveling is performed using excavator bucket teeth or a special leveler, and is completed before the curing agent initially sets.

[0014] Preferably, after the curing period in step S4, a quality inspection step is also included: the bearing capacity of the foundation is tested using a light dynamic penetration test, with a testing frequency of no less than 6 measuring points every 30 meters along the longitudinal direction of the route, or in every 2000 square meter block.

[0015] The beneficial effects of this invention are as follows: In this invention, when the treatment area is adjacent to an embankment slope, a skip-section construction sequence is adopted. Before mixing any target block, the soil is excavated, and the construction blocks, arranged continuously along the longitudinal direction of the slope, are constructed in an interval-wise sequence. This construction method effectively reduces disturbance to the slope during mixing, preventing landslides and collapses caused by vibration and compression, thus ensuring construction safety and the stability of the surrounding environment. Compared to traditional foundation treatment methods, in-situ solidification construction does not require large-scale earthwork excavation and transportation, reducing dust and noise pollution during construction and having a smaller impact on the surrounding environment, aligning with the concept of green construction. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0017] In the attached image:

[0018] Figure 1 This is a schematic diagram of the in-situ consolidation construction method for soft soil foundations adjacent to embankments. Detailed Implementation

[0019] The technical solution of the present invention will now be described with reference to the accompanying drawings. However, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, the present invention provides a method for in-situ consolidation of soft soil foundation adjacent to an embankment, comprising the following steps: S1: Construction preparation, including surveying, clearing and leveling the area to be solidified; if there is a hard shell layer on the site, the hard shell layer of the corresponding construction block shall be pre-loosened using excavation equipment before mixing and solidification.

[0021] Specifically, a comprehensive geological survey is conducted on the area to be solidified, and soil samples are obtained at different depths using geological drilling equipment. The physical and mechanical properties of the soft soil, such as water content, void ratio, and compression modulus, are analyzed. At the same time, the groundwater level is determined to provide basic data for the determination of subsequent construction parameters.

[0022] Use bulldozers, graders and other mechanical equipment to remove vegetation, humus, debris and other impurities from the surface of the area to be hardened, ensuring the cleanliness of the construction site and preventing these substances from affecting the full mixing of the hardener and the soft soil.

[0023] The site is initially leveled using a grader to make the surface roughly flat, creating favorable conditions for subsequent construction block division and mixing and solidification operations. If a hard crust layer exists on the site, the bucket of excavating equipment (such as an excavator) is used to pre-loosen the hard crust layer in the corresponding construction block, breaking it up and loosening it to a certain depth to improve the mixing effect of soft soil and solidifying agent.

[0024] It also includes the safety deployment steps for cement storage tanks: cement storage tanks are installed next to the construction area, and the cement storage tanks are fixed by multiple guy ropes. Each guy rope is connected to an independent counterweight at its lower end, and an anti-overturning calculation is required after installation.

[0025] Specifically, cement storage tanks are installed at appropriate locations near the construction area. The capacity of the storage tanks is determined based on the scale and duration of the construction. The storage tanks are secured with multiple guy ropes, each with an independent counterweight at its lower end. The weight of the counterweight is calculated based on the weight of the storage tank and factors such as wind force, ensuring the stability of the storage tanks during construction. After installation, anti-overturning calculations are performed using professional mechanical calculation methods, considering adverse factors such as wind loads and seismic loads, to ensure that the overturning resistance of the cement storage tanks meets safety requirements.

[0026] S2: Area division, which divides the processing area into multiple consecutive construction blocks.

[0027] Specifically, the treatment area is divided into multiple consecutive construction blocks. The division of these blocks must comprehensively consider factors such as the distribution of soft soil, the operating range of construction equipment, and construction efficiency. For example, based on variations in soft soil thickness and geological conditions, areas with similar thickness and geological conditions are grouped into the same construction block to allow for the application of identical construction parameters. Furthermore, the construction blocks should be as regularly shaped as possible, generally rectangular or square, to facilitate the operation of construction equipment and construction management.

[0028] It also includes supplementary exploration steps: static penetration test holes are laid out longitudinally along the treatment area at intervals of 5 to 20 meters, and the solidification treatment depth and range of each construction block are finally determined based on the penetration test results.

[0029] Specifically, static cone penetration tests (CPUTs) are laid out longitudinally along the treatment area at intervals of 5 to 20 meters. The depth of the CPUTs is determined based on the thickness of the soft soil and the expected solidification depth. A static cone penetrometer is used to press the probe into the soil at a certain rate. By measuring the resistance of the probe in the soil, mechanical properties of the soil, such as cone tip resistance and sidewall friction, are obtained. Based on the penetration test results and combined with preliminary survey data, the final solidification depth and range for each construction block are determined, providing accurate construction parameters for subsequent mixing and solidification operations.

[0030] S3: Mixing and curing. Excavation equipment equipped with a mixing head is used to carry out sinking and lifting mixing in the construction block, and the curing agent slurry is sprayed in simultaneously. When the treatment area is adjacent to the embankment slope, in step S3, the construction blocks located at the toe of the slope are constructed in a skip-building sequence: before the mixing operation of any target block begins, the soil of the target block is excavated; and the construction blocks arranged continuously along the longitudinal direction of the slope are constructed in sequence with one or more blocks spaced apart. The construction sequence is as follows: along the longitudinal direction of the slope, first construct all construction blocks with odd numbers, then construct all construction blocks with even numbers; or, first construct all construction blocks with even numbers, then construct all construction blocks with odd numbers.

[0031] Specifically, excavation equipment equipped with a three-dimensional mixing head is used for the mixing and solidification operation. The three-dimensional mixing head consists of mixing blades, a mixing shaft, and connecting rods. The mixing blades are spirally distributed, enabling comprehensive mixing of the soil during the mixing process, ensuring thorough mixing of the solidifying agent and soft soil. The mixing head rotates at 50 to 120 revolutions per minute, and the rotation speed is controlled by adjusting the motor speed to ensure effective mixing. The verticality deviation of the mixing head connecting rod is no more than 2%. During installation, professional measuring instruments (such as a total station) are used to accurately measure and adjust the verticality of the connecting rod, ensuring that the mixing head can vertically descend and rise during the mixing process, avoiding uneven mixing due to rod tilting.

[0032] When the treatment area is adjacent to an embankment slope, the construction blocks located at the toe of the slope are constructed in a skip-section sequence. Construction blocks arranged continuously along the longitudinal direction of the slope are constructed sequentially, with one or more blocks spaced apart. Specifically, the skip-section sequence is as follows: along the longitudinal direction of the slope, first construct all construction blocks with odd numbers, then construct all construction blocks with even numbers; or, first construct all construction blocks with even numbers, then construct all construction blocks with odd numbers. Before the mixing operation begins in any target block, the soil in that target block is excavated. The excavation depth is determined according to design requirements and actual site conditions, generally a portion of the solidification treatment depth, to reduce disturbance to the slope during mixing and ensure slope stability.

[0033] The excavation equipment lowers the mixing head to the design elevation. During the descent, the mixing head begins to rotate, initially mixing the soil. After reaching the design elevation, the mixing head's lifting speed is controlled between 15 and 20 seconds per meter within 0.5 meters above the pile bottom. By controlling the lifting speed, the curing agent and soil are thoroughly mixed within this range, forming a uniform solidified soil mass. Then, the mixing head is lifted, and during this lifting process, curing agent slurry is simultaneously sprayed in. The curing agent slurry is a cement slurry, and its cement content is dynamically adjusted based on the moisture content and wet density test results of the soil samples on site, with a mixing ratio ranging from 4% to 6% of the weight of the soil to be solidified. By adjusting the flow rate of the cement slurry and the mixing speed of the mixing head, it is ensured that the cement slurry is fully mixed with the soft soil, forming a solidified soil mass with a certain strength and stability.

[0034] S4: Leveling and curing, leveling and covering the solidified soil; leveling is carried out using excavator bucket teeth or a special leveler, and is completed before the curing agent initially sets.

[0035] Specifically, leveling is performed using excavator bucket teeth or a dedicated leveling tool. When using excavator bucket teeth, the excavator's operation is adjusted to allow the bucket teeth to scrape and compact the surface of the solidified soil, leveling uneven soil to the design elevation. When using a dedicated leveling tool, the tool is mounted on the construction equipment, and the movement of the equipment causes the leveling tool to roll or slide on the surface of the solidified soil, achieving leveling. Leveling work must be completed before the hardener initially sets to avoid the soil becoming harder and more difficult to level after the hardener has set.

[0036] After leveling, the solidified soil is covered for curing. Covering materials can include plastic film, geotextile, etc. The purpose of covering is to retain moisture in the solidified soil and prevent excessive evaporation, which would affect the curing effect. The curing time depends on the type of curing agent and environmental conditions, generally ranging from 7 to 14 days.

[0037] It also includes quality inspection steps: using a light dynamic penetration test to test the foundation bearing capacity, with a testing frequency of no less than 6 testing points every 30 meters along the route or in every 2000 square meter block.

[0038] Specifically, the lightweight dynamic penetrometer consists of a drop hammer, a penetrometer rod, and a probe. During testing, the penetrometer rod is driven vertically into the solidified soil, and the drop hammer falls freely with a certain amount of energy, impacting the probe. By measuring the penetration depth of the probe into the soil, the bearing capacity of the foundation is calculated. The testing frequency is no less than 6 measuring points every 30 meters along the longitudinal direction of the route, or within a block of 2000 square meters. Through multi-point testing, the bearing capacity distribution of the solidified foundation can be comprehensively understood, ensuring that the foundation quality meets the design requirements.

[0039] This invention has many applications, including but not limited to the following described scenarios: In highway construction, soft soil foundations are frequently encountered. When a highway embankment is adjacent to a soft soil foundation, this in-situ consolidation construction method can effectively treat the soft soil foundation, improve the stability of the embankment, reduce embankment settlement and deformation, and ensure the safe operation of the highway. For example, in highway construction in coastal areas or near lakes and rivers, where soft soil is widely distributed, this technical solution can play an important role.

[0040] For old road reconstruction projects, when it is necessary to reinforce the original soft soil foundation, on-site solidification construction does not require damage to the original road surface structure, making construction convenient and quick, reducing the impact on traffic, and shortening the construction period.

[0041] Railways have high requirements for foundation stability and settlement control. In railway embankment construction, when encountering soft soil foundations, this technical solution can ensure that the solidified foundation meets the requirements for railway operation through precise construction parameter control and quality control measures. Especially in high-speed railway construction, where the requirements for foundation flatness and uniformity are extremely high, in-situ solidification construction can achieve uniform solidification of soft soil, providing a guarantee for the safe operation of high-speed railways.

[0042] Water conservancy dike projects are typically built near rivers, lakes, and other bodies of water, with foundations often consisting of soft soil. This in-situ consolidation construction method can strengthen the dike foundation, improve its anti-sliding stability and erosion resistance, and prevent breaches during floods. For example, this technology has broad application prospects in dike reinforcement projects along major rivers such as the Yangtze and Yellow Rivers.

[0043] In urban construction, soft soil foundations are frequently encountered in infrastructure projects such as municipal roads and plazas. This in-situ consolidation construction method allows for construction within limited urban spaces, minimizing the impact on the surrounding environment and traffic. Simultaneously, the consolidated foundation meets the load-bearing capacity and flatness requirements of municipal roads and plazas, improving the quality and lifespan of urban infrastructure.

[0044] Some industrial plants require high foundation bearing capacity. When built on soft soil foundations, this in-situ consolidation construction method can quickly and effectively treat the soft soil foundation, providing a stable foundation for the plant construction. For example, in the construction of plants in industries such as chemical and machinery manufacturing, this technical solution can ensure the normal operation of equipment and the safe use of the plant.

[0045] In residential construction, when encountering soft soil foundations, on-site consolidation can improve foundation stability, reduce settlement and cracking issues, and enhance the quality and safety of the housing. This technology is particularly useful in areas with poor geological conditions, providing residents with a more comfortable living environment.

Claims

1. A method for in-situ consolidation of soft soil foundation adjacent to an embankment, characterized in that, Includes the following steps: S1: Construction preparation, including surveying, clearing and leveling the area to be solidified; S2: Area division, which divides the processing area into multiple consecutive construction blocks; S3: Mixing and curing. Excavation equipment equipped with a mixing head is used to carry out sinking and lifting mixing in the construction block, and the curing agent slurry is sprayed in simultaneously. S4: Leveling and curing, leveling and covering the solidified soil for curing; When the treatment area is adjacent to the embankment slope, in step S3, the construction blocks located at the toe of the slope are constructed in a skip-building sequence: before the mixing operation of any target block begins, the soil of the target block is excavated; and the construction blocks arranged continuously along the longitudinal direction of the slope are constructed in sequence with one or more blocks spaced apart.

2. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, In step S3, the construction sequence is as follows: along the longitudinal direction of the slope, first construct all construction blocks with odd numbers, then construct all construction blocks with even numbers; or, first construct all construction blocks with even numbers, then construct all construction blocks with odd numbers.

3. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, After the mixing head is lowered to the design elevation, its lifting speed is controlled between 15 and 20 seconds per meter within 0.5 meters above the bottom of the pile.

4. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, In step S1, if a hard shell layer exists on the site, the hard shell layer of the corresponding construction block is pre-loosened using excavation equipment before mixing and solidification.

5. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, In step S3, the curing agent slurry is a cement slurry, and the amount of cement added is dynamically adjusted according to the test results of the soil moisture content and wet density on site. The addition ratio ranges from 4% to 6% of the weight of the soil to be cured.

6. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, Before step S3, a supplementary exploration step is also included: static penetration test holes are laid out longitudinally along the treatment area at intervals of 5 to 20 meters, and the solidification treatment depth and range of each construction block are finally determined based on the penetration test results.

7. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, In step S3, the stirring head is a three-dimensional stirring head with a rotation speed of 50 to 120 revolutions per minute, and the verticality deviation of the stirring head connecting rod is no more than 2%.

8. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, Step S1 also includes a safe deployment step for cement storage tanks: installing cement storage tanks next to the construction area, with the cement storage tanks fixed by multiple guy ropes, each guy rope having an independent counterweight connected to its lower end, and an anti-overturning calculation being performed after installation.

9. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, In step S4, leveling is carried out using excavator bucket teeth or a special leveler, and is completed before the curing agent initially sets.

10. The method for in-situ consolidation of soft soil foundation adjacent to an embankment according to claim 1, characterized in that, After the curing period in step S4 is completed, a quality inspection step is also included: the bearing capacity of the foundation is tested using a light dynamic penetration test method, with a testing frequency of no less than 6 measuring points every 30 meters along the longitudinal direction of the route, or in every 2000 square meter block.

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