A method for accelerating consolidation of soft soil foundation based on controlled freeze-thaw

Abstract

The application relates to the technical field of geotechnical engineering foundation treatment, and discloses a soft soil foundation accelerated consolidation method based on controlled freezing and thawing. According to the engineering site geological conditions, the soft soil foundation area to be treated is surveyed and partitioned; the freezing drainage pipes extending to the soft soil layer are vertically arranged at certain intervals from the surface in the treatment area; the low-temperature refrigerant is transported to the soil body through the freezing drainage pipes, so that the pore water is frozen to form a freezing influence area; the pore structure inside the soil body is disturbed by the volume expansion of the water body during the freezing process, new pore and fissure structures are formed; then the soil body is naturally or actively thawed, the pore structure is kept in a partially open state to improve the soil body permeability; after the freezing and thawing treatment is completed, the load is applied to the foundation through the preloading or vacuum preloading mode, the pore water is quickly discharged in the initial consolidation stage, the foundation is acceleratedly consolidated, the application can improve the drainage efficiency, accelerate the consolidation rate, and shorten the soft soil foundation treatment period.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering foundation treatment technology, and in particular to a method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles. Background Technology

[0002] In engineering construction in coastal areas and river and lake sedimentary areas, thick layers of soft soil foundations are often encountered. This type of soil typically has characteristics such as high water content, large void ratio, strong compressibility, and low permeability coefficient. Under engineering loads, it is prone to large consolidation settlement. Therefore, soft soil foundations usually need to be treated before engineering construction.

[0003] Currently, commonly used methods for treating soft soil foundations in engineering include surcharge preloading, vacuum preloading, and drainage consolidation. Among these, drainage consolidation typically uses drainage structures such as sand wells or plastic drainage boards to shorten the drainage path of pore water, thereby increasing the consolidation rate. This method has been widely used in engineering practice. However, for deep or thick soft soil foundations, even with drainage structures, the drainage process of pore water within the soil remains relatively slow. This is mainly because soft soil itself has a low permeability coefficient, and during the consolidation process, as the soil compacts, its permeability often further decreases, thus limiting the improvement of drainage efficiency. This results in a longer time required for the foundation to reach the designed degree of consolidation, consequently affecting the construction progress.

[0004] On the other hand, artificial freezing technology has been widely used in underground engineering, mainly for temporary support or water stopping during underground structure construction. This technology freezes pore water by lowering the soil temperature, thereby forming frozen soil with a certain strength to improve soil stability. However, existing freezing technology is usually used as a temporary engineering measure, with its main purpose being to improve soil strength or achieve water stopping.

[0005] During freezing and thawing, the internal pore structure of soil may change to some extent, such as pore expansion, microcrack formation, and alteration of pore connectivity. Although the effects of freeze-thaw cycles on soil microstructure are understood to some extent in relevant studies, current engineering techniques have not yet integrated freeze-thaw cycles with the drainage consolidation process of soft soil foundations.

[0006] Therefore, how to utilize the effects of freeze-thaw cycles on soil pore structure, actively regulate soil permeability and improve drainage efficiency, thereby shortening the consolidation time of soft soil foundations, remains a pressing technical problem in the field of geotechnical engineering. Summary of the Invention

[0007] The purpose of this invention is to provide a method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles, aiming to solve or improve at least one of the above-mentioned technical problems. By controlling the pore structure of deep soft soil through a single controlled freeze-thaw cycle and working in conjunction with a drainage system, the soil forms high-permeability channels in the early stage of consolidation, enabling rapid drainage of pore water, thereby improving drainage efficiency, accelerating the consolidation rate, and shortening the treatment cycle of soft soil foundations.

[0008] To achieve the above objectives, the present invention provides the following solution: The present invention provides a method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles, comprising: Layout of foundation treatment area: Based on the geological conditions of the project site, the soft soil foundation area to be treated is investigated and divided into zones to determine the basic parameters of soft soil layer thickness, natural water content, compressibility coefficient and permeability coefficient; within the treatment area, frozen drainage pipes extending vertically from the ground surface to the soft soil layer at certain intervals are arranged. Controlled freeze-thaw treatment: Low-temperature refrigerant is delivered to the soil through the freeze drainage pipe, lowering the soil temperature to the range of -5℃ to -20℃, causing pore water to freeze and form a freeze-affected zone; during the freezing process, the volume expansion of the water as it freezes disturbs the internal pore structure of the soil, forming new pores and fissures; subsequently, the soil is allowed to thaw naturally or actively, keeping the pore structure partially open to improve soil permeability. Drainage consolidation: After the freeze-thaw treatment is completed, the foundation is loaded by surcharge preloading or vacuum preloading to allow pore water to be discharged quickly in the early stage of consolidation, thereby accelerating the consolidation of the foundation.

[0009] Optionally, the spacing of the frozen drainage pipes is determined based on the thickness H of the soft soil layer: When H≤5m, the spacing between plants should be 1.0~1.5m; When 5m < H ≤ 10m, the spacing between plants should be 1.2 to 2.0m. When 10m < H ≤ 20 m, the spacing between plants should be 1.5 to 2.5 m. When H > 20m, the spacing between the plants is 2.0 to 3.0m.

[0010] Optionally, the freezing duration of the controlled freeze-thaw treatment is determined based on the soil layer thickness and freezing radius, where the freezing radius Rf≥S / 2, and S is the spacing between the layers; the freezing duration t is calculated using the formula t=Rf² / (4α), where α is the thermal diffusivity of the soil; the actual freezing duration is 5 to 10 times the theoretically calculated value.

[0011] Optionally, the controlled freeze-thaw treatment may be implemented using one of the following methods depending on the construction requirements: Method 1: Freeze-thaw-drain before surcharge, that is, freeze-thaw the soil before applying surcharge preloading or vacuum preloading, and then apply the load. Method 2: Intermittent loading method, which involves subjecting the soil to freeze-thaw treatment during the intermittent loading process to fine-tune the soil pore structure.

[0012] Optionally, for deep soil, segmented freezing or cyclic freeze-thaw treatment can be used, wherein the cyclic freeze-thaw treatment involves multiple freezing-thawing cycles of the soil.

[0013] Optionally, the negative pressure of the vacuum pre-compression is 50 to 90 kPa.

[0014] Optionally, the surcharge preloading adopts a graded loading method, with the surcharge amount of each grade adjusted by ±10% to 20% according to the design grade, the surcharge interval time being 1 to 7 days, and the number of surcharge layers being 1 to more than 10 layers.

[0015] Optionally, the frozen drainage pipe is arranged vertically along the foundation, in a square or triangular arrangement.

[0016] Optionally, monitoring and control steps are also included: during the consolidation process, the foundation settlement rate curve and pore water pressure dissipation curve are obtained through settlement monitoring and pore water pressure monitoring, and the freeze-thaw parameters and loading methods are dynamically adjusted based on the monitoring results.

[0017] Optionally, the dynamic adjustment of the freeze-thaw parameters and loading method includes: When the pore water pressure dissipates slowly, reduce the refrigerant temperature or increase the number of freeze-thaw cycles. When the soil settlement rate is low, extend the freezing duration; When solidification lags in a certain area, reduce the spacing between the refrigerant tubes in that area; When the pore water pressure has not dissipated, the load capacity should be appropriately reduced or the load should be applied in stages. When initial settlement is delayed, extend the surcharge interval. When the settlement rate is uneven, adjust the number of surcharge layers; When the pore water pressure dissipates slowly, increase the negative pressure.

[0018] The present invention discloses the following technical effects: This invention can actively improve pore structure, not only by shortening traditional drainage paths but also by fundamentally improving soil drainage capacity. Through controlled freeze-thaw treatment, the expansion of water during freezing disturbs the pore structure inside the soil, forming new pores and fissures, keeping the pore structure partially open, and significantly improving soil permeability.

[0019] This invention enables the formation of highly interconnected drainage channels, achieving efficient drainage during the initial consolidation phase. Due to the pore structure reconstruction resulting from the freeze-thaw process, the soil permeability is high in the initial consolidation stage, allowing pore water to be rapidly discharged through internal soil channels and drainage structures, thereby increasing the pore water pressure dissipation rate. As consolidation progresses and the soil gradually compacts, permeability may decrease, but the main drainage process has already been completed in the initial stage, thus significantly shortening the overall consolidation time.

[0020] This invention is compatible with conventional foundation treatment methods, improving construction efficiency and expanding its applicability. It can be used in conjunction with conventional foundation treatment methods such as surcharge preloading or vacuum preloading without altering existing construction techniques, demonstrating excellent engineering adaptability.

[0021] This invention is applicable to the treatment of large areas and soft soils of varying depths, achieving pore structure improvement from shallow to deep layers. By adjusting parameters such as the spacing of the freezing drainage pipes and the freezing duration, it can adapt to the treatment needs of soft soil layers of different thicknesses, achieving effective pore structure improvement from shallow to deep layers.

[0022] This invention enables controllable evolution of pore structure, and improves construction operability by optimizing freeze-thaw action and loading strategies through parameter adjustment. Through monitoring and control methods, freeze-thaw parameters and loading methods can be dynamically adjusted based on foundation settlement rate curves and pore water pressure dissipation curves, achieving precise control.

[0023] This invention offers good engineering economics, achieving accelerated foundation consolidation without the need for large quantities of solidification materials. It primarily utilizes physical freeze-thaw cycles to improve soil structure, eliminating the need for extensive chemical curing agents and thus exhibiting good environmental and economic benefits. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a construction diagram of the present invention.

[0025] In the diagram: 1. Ground surface; 2. Soft soil layer; 3. Frozen drainage pipe; 4. Frozen impact zone. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Reference Figure 1 This invention provides a method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles, comprising: Layout of foundation treatment area: Based on the geological conditions of the project site, the soft soil foundation area to be treated is investigated and divided into zones to determine the basic parameters of the soft soil layer 2 thickness, natural water content, compression coefficient and permeability coefficient; within the treatment area, frozen drainage pipes 3 are vertically arranged from the ground surface 1 to the soft soil layer 2 at certain intervals. Controlled freeze-thaw treatment: Low-temperature refrigerant is delivered to the soil through the freeze drainage pipe 3, lowering the soil temperature to the range of -5℃ to -20℃, causing pore water to freeze and forming a freeze-affected zone 4; during the freezing process, the expansion of the water volume when it freezes disturbs the internal pore structure of the soil, forming new pores and cracks; subsequently, the soil is allowed to thaw naturally or actively, keeping the pore structure partially open to improve soil permeability. Drainage consolidation: After the freeze-thaw treatment is completed, the foundation is loaded by surcharge preloading or vacuum preloading to allow pore water to be discharged quickly in the early stage of consolidation, thereby accelerating the consolidation of the foundation.

[0029] By controlling the pore structure of deep soft soil through a single freeze-thaw cycle and working in conjunction with the drainage system, high permeability channels are formed in the soil during the initial consolidation stage, enabling rapid drainage of pore water. This improves drainage efficiency, accelerates the consolidation rate, and shortens the treatment cycle for soft soil foundations.

[0030] In this embodiment, the spacing of the frozen drainage pipes 3 is determined based on the thickness H of the soft soil layer 2: When H≤5m, the arrangement spacing is 1.0~1.5m, which can achieve rapid consolidation and meet the requirements of high-standard projects; When 5m < H ≤ 10m, the arrangement spacing is 1.2 to 2.0m, which is suitable for conventional accelerated consolidation projects; When 10m < H ≤ 20 m, the spacing between the plants should be 1.5 to 2.5 m, taking into account both treatment effectiveness and economy. When H > 20m, the spacing between the plants should be 2.0 to 3.0m, and layered treatment should be used to effectively treat ultra-thick soft soil.

[0031] This tiered layout strategy is based on Barron's radial consolidation theory, where consolidation time is proportional to the square of the drainage influence radius. By appropriately reducing the layout spacing, the radial drainage control range is narrowed, which can significantly shorten the consolidation time.

[0032] Engineering practice shows that using a 1.0m spacing can shorten the consolidation time by 40% to 60%, a 1.5m spacing by 30% to 50%, a 2.0m spacing by 20% to 35%, a 2.5m spacing by 10% to 25%, and a 3.0m spacing by <15%, achieving the best match between treatment effect and engineering cost.

[0033] In this embodiment, the freezing duration of the controlled freeze-thaw treatment is determined based on the soil layer thickness and the freezing radius, where the freezing radius Rf≥S / 2, and S is the spacing between the layers; the freezing duration t is calculated using the formula t=Rf² / (4α), where α is the thermal diffusivity of the soil; the actual freezing duration is 5 to 10 times the theoretically calculated value.

[0034] With the freezing radius Rf≥S / 2 as the control target, adjacent freezing zones are ensured to overlap to form a continuous freezing influence zone 4, avoiding blind spots in the treatment; the theoretical freezing time is calculated using the formula t=Rf² / (4α), where α is the soil thermal diffusivity coefficient, ensuring the scientific basis of the calculation; the actual freezing duration is taken as 5 to 10 times the theoretical calculation value, fully considering engineering practical factors such as high soil moisture content, latent heat effect, and heterogeneity, to ensure that the freeze-thaw action is fully carried out.

[0035] This parameter control method can achieve the following freezing durations: approximately 7–10 days for shallow layers (H≤1m); approximately 63–70 days for medium layers (H≈2–3m); and approximately 112–190 days for thick layers (H≈3–5m). By extending the freezing duration, the disturbance of the pore structure can be increased, further improving the initial permeability and ensuring the drainage consolidation effect.

[0036] In this embodiment, the controlled freeze-thaw treatment is implemented using one of the following methods based on construction requirements: Method 1: Freeze-thaw-drain before surcharge, that is, freeze-thaw the soil before applying surcharge preloading or vacuum preloading, and then apply the load. Before applying surcharge preloading or vacuum preloading, the soil undergoes a freeze-thaw process to keep the pore structure partially open, significantly increasing the permeability coefficient. Subsequently, when load is applied, pore water is rapidly discharged in the initial stage, accelerating consolidation settlement and shortening the overall consolidation period. This method is suitable for projects with tight deadlines and requiring rapid achievement of consolidation.

[0037] Method 2: Intermittent loading method, which involves subjecting the soil to freeze-thaw treatment during the intervals between loading stages to fine-tune the soil's pore structure. During the surcharge loading process, freeze-thaw treatment is applied to the soil during the intervals between each loading stage. This fine-tunes the soil's pore structure, increasing the number of pores and fissures and improving drainage channels. Synergistically with the surcharge consolidation process, the rate of pore water pressure dissipation increases, causing the main drainage process to occur in the high-permeability stage, thus accelerating the overall consolidation process. This method is suitable for projects requiring precise settlement control and layered treatment of deep, soft soil.

[0038] In this embodiment, segmented freezing or cyclic freeze-thaw treatment is adopted for deep soil. Cyclic freeze-thaw treatment involves multiple freeze-thaw cycles on the soil. This measure can effectively solve the problem of slow consolidation of deep soft soil due to long drainage paths and poor permeability, achieve pore improvement from shallow to deep coverage, and expand the applicability of this method.

[0039] Segmented freezing divides the deep soft soil layer 2 into several treatment sections, implementing freeze-thaw treatment segment by segment to ensure effective pore structure improvement at each depth level and avoid insufficient treatment of deep soil layers. Cyclic freeze-thaw involves subjecting the soil to multiple freeze-thaw cycles. Through repeated volume expansion and contraction, the number of pores and fissures is further increased, the drainage channel network is optimized, and the degree of improvement in soil permeability is enhanced.

[0040] In this embodiment, the negative pressure of the vacuum pre-compression is 50-90 kPa.

[0041] By controlling the vacuum preloading negative pressure within the range of 50–90 kPa, when the negative pressure is below 50 kPa, the driving force for pore water discharge is insufficient, limiting the improvement in consolidation rate; when the negative pressure is above 90 kPa, it may cause problems such as soil structure damage and excessive load on vacuum equipment. Within the range of 50–90 kPa, pore water discharge can be effectively accelerated, increasing the consolidation rate while ensuring construction safety and equipment reliability. This parameter range, in synergy with controlled freeze-thaw treatment, can utilize the improved high permeability in the early stages of consolidation to quickly dissipate pore water pressure, significantly shortening the overall consolidation time.

[0042] In this embodiment, the surcharge preloading adopts a graded loading method, with the surcharge amount of each grade adjusted by ±10% to 20% according to the design grade, the surcharge interval time being 1 to 7 days, and the number of surcharge layers being 1 to more than 10 layers.

[0043] By employing a graded loading method, dynamic matching between load application and soil consolidation state is achieved. Each load increment is adjusted by ±10% to 20% of the design increment, allowing for flexible adjustment of the loading rate based on on-site monitoring data. This prevents excessively rapid loading that could lead to pore water pressure buildup. The loading interval ranges from 1 to 7 days, providing sufficient time for pore water pressure dissipation and preventing localized overpressure. The number of loading layers can range from 1 to multiple layers, adapting to different project scales and schedule requirements. This graded loading strategy effectively controls settlement rate, prevents foundation instability, ensures a safe and controllable consolidation process, and improves project reliability.

[0044] In this embodiment, the frozen drainage pipe 3 is arranged vertically along the foundation, and the arrangement can be either square or triangular.

[0045] By optimizing the layout of chilled water drainage pipes, uniform coverage of the treatment area and maximum drainage efficiency can be achieved. A square layout is simple to construct, suitable for regularly shaped treatment areas, and easy to coordinate with existing drainage systems. A triangular layout, with the same spacing, can create a denser coverage of the chilled area affected by freezing, improving treatment uniformity and suitable for projects with high treatment effect requirements. Both layouts can be selected based on site conditions and treatment requirements, increasing the flexibility and adaptability of the method.

[0046] In this embodiment, a monitoring and control step is also included: during the consolidation process, the foundation settlement rate curve and pore water pressure dissipation curve are obtained through settlement monitoring and pore water pressure monitoring, and the freeze-thaw parameters and loading method are dynamically adjusted according to the monitoring results.

[0047] By establishing a comprehensive monitoring and control system, dynamic optimization of the foundation treatment process can be achieved. Settlement monitoring obtains the foundation settlement rate curve to understand the soil consolidation development state. Pore water pressure monitoring obtains the pore water pressure dissipation curve to evaluate the drainage consolidation effect. Based on the monitoring results, freeze-thaw parameters and loading methods are adjusted in real time to achieve precise control. This monitoring and control mechanism can promptly detect anomalies in the treatment process and take targeted measures to ensure that the foundation treatment achieves the design objectives, thereby improving project quality and reliability.

[0048] In this embodiment, the dynamic adjustment of freeze-thaw parameters and loading method includes: When pore water pressure dissipates slowly, lowering the refrigerant temperature or increasing the number of freeze-thaw cycles can increase microcrack formation and improve permeability. When the soil settlement rate is low, extending the freezing duration increases the disturbance of the pore structure and further improves the initial permeability. When consolidation is lagging in a certain area, reduce the spacing between the refrigeration pipes in that area, shorten the drainage path, and improve the local consolidation efficiency. When the pore water pressure has not dissipated, the load capacity should be appropriately reduced or the load should be applied in stages to avoid local overpressure caused by excessively rapid loading. When initial settlement is delayed, extend the surcharge interval to allow time for pore water to drain and avoid local water stagnation. When the settlement rate is uneven, adjust the number of surcharge layers to control the pressure uniformity and improve freeze-thaw porosity. When the pore water pressure dissipates slowly, increasing the negative pressure accelerates the discharge of pore water and increases the consolidation rate.

[0049] Engineering experience shows that a 5°C reduction in freeze-thaw temperature increases the pore water pressure dissipation rate by 20%, the initial consolidation rate by 15%, and the total consolidation time to 10% of the baseline value. Increasing the number of freeze-thaw cycles by one increases the pore water pressure dissipation rate by 25%, the initial consolidation rate by 20%, and the total consolidation time to 15% of the baseline value. Extending the surcharge interval by two days increases the pore water pressure dissipation rate by 10%, the initial consolidation rate by 10%, and the total consolidation time to 5% of the baseline value. Using a combination of optimization measures (lower temperature + increased number of cycles + extended interval), the pore water pressure dissipation rate can be increased by 50%, the initial consolidation rate by 40%, and the total consolidation time to 3% of the baseline value, significantly improving foundation treatment efficiency.

[0050] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles, characterized in that, include: Layout of foundation treatment area: Based on the geological conditions of the engineering site, the soft soil foundation area to be treated is investigated and divided into zones, and the basic parameters of the soft soil layer (2), natural water content, compression coefficient and permeability coefficient are determined; in the treatment area, frozen drainage pipes (3) extending vertically from the ground surface (1) to the soft soil layer (2) are arranged at certain intervals. Controlled freeze-thaw treatment: Low-temperature refrigerant is delivered to the soil through the freeze drainage pipe (3) to reduce the soil temperature to the range of -5℃ to -20℃, causing the pore water to freeze and form a freeze-affected zone (4); During the freezing process, the expansion of the water volume during freezing disturbs the pore structure inside the soil, forming new pores and cracks; Subsequently, the soil is allowed to thaw naturally or actively, keeping the pore structure partially open to improve the soil permeability; Drainage consolidation: After the freeze-thaw treatment is completed, the foundation is loaded by surcharge preloading or vacuum preloading to allow pore water to be discharged quickly in the early stage of consolidation, thereby accelerating the consolidation of the foundation.

2. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, The spacing of the frozen drainage pipes (3) is determined according to the thickness H of the soft soil layer (2): When H≤5m, the spacing between plants should be 1.0~1.5m; When 5m < H ≤ 10m, the spacing between plants should be 1.2 to 2.0m. When 10m < H ≤ 20 m, the spacing between plants should be 1.5 to 2.5 m. When H > 20m, the spacing between the plants is 2.0 to 3.0m.

3. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, The freezing duration of the controlled freeze-thaw treatment is determined based on the soil layer thickness and freezing radius, where the freezing radius Rf≥S / 2, and S is the spacing between the layers. The freezing duration t is calculated using the formula t=Rf² / (4α), where α is the thermal diffusivity of the soil. The actual freezing duration is 5 to 10 times the theoretically calculated value.

4. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, The controlled freeze-thaw treatment shall be implemented using one of the following methods according to construction requirements: Method 1: Freeze-thaw-drain before surcharge, that is, freeze-thaw the soil before applying surcharge preloading or vacuum preloading, and then apply the load. Method 2: Intermittent loading method, which involves subjecting the soil to freeze-thaw treatment during the intermittent loading process to fine-tune the soil pore structure.

5. The method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles according to claim 1, characterized in that, For deep soil, segmented freezing or cyclic freeze-thaw treatment is adopted, wherein the cyclic freeze-thaw treatment involves multiple freezing-thawing cycles of the soil.

6. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, The negative pressure of the vacuum pre-compression is 50–90 kPa.

7. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, The preloading is carried out in stages, with each stage of load adjusted by ±10% to 20% of the design stage. The inter-load interval is 1 to 7 days, and the number of load layers is 1 to more than 10 layers.

8. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, The frozen drainage pipe (3) is arranged vertically along the foundation, and the arrangement is either square or triangular.

9. The method for accelerating the consolidation of soft soil foundation based on controlled freeze-thaw as described in claim 1, characterized in that, It also includes monitoring and control steps: during the consolidation process, the foundation settlement rate curve and pore water pressure dissipation curve are obtained through settlement monitoring and pore water pressure monitoring, and the freeze-thaw parameters and loading methods are dynamically adjusted according to the monitoring results.

10. A method for accelerating the consolidation of soft soil foundations based on controlled freeze-thaw cycles according to claim 9, characterized in that, The dynamic adjustment of the freeze-thaw parameters and loading method includes: When the pore water pressure dissipates slowly, the refrigerant temperature should be lowered or the number of freeze-thaw cycles should be increased. When the soil settlement rate is low, extend the freezing duration; When solidification lags in a certain area, reduce the spacing between the refrigerant tubes in that area; When the pore water pressure has not dissipated, the load capacity should be appropriately reduced or the load should be applied in stages. When initial settlement is delayed, extend the surcharge interval. When the settlement rate is uneven, adjust the number of surcharge layers; When the pore water pressure dissipates slowly, increase the negative pressure.

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