A method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas

Abstract

This application relates to the field of foundation reinforcement and correction technology, and specifically to a method for reinforcing and correcting weak foundations in collapsible loess areas affected by water infiltration. The method involves using quicklime piles to drain water sources around the building to be reinforced and to seal and limit the spread of water in the infiltrated area; using lightweight wellpoint dewatering to drain free water within the water-soaked area of ​​the foundation; and using borehole recharge to correct and adjust the settlement and tilt of the building. After the quicklime piles have fully absorbed water and consolidated, and the soil strength reaches the set requirements, the dewatering wells and recharge wells are backfilled and sealed. Data is collected periodically by installing moisture sensors and settlement observation points to determine whether the soil is approaching a stable state. This method is suitable for treating foundation instability and building tilting in collapsible loess caused by external water infiltration, avoiding secondary damage to buildings caused by large-scale excavation, and has advantages such as convenient construction and minimal environmental impact.

Description

Technical Field

[0001] This application relates to the field of foundation reinforcement and correction technology, and in particular to a method for reinforcing and correcting weak foundations in waterlogged loess areas. Background Technology

[0002] Collapsible loess exhibits high strength and low compressibility in its naturally dry state, but it is prone to significant collapsing deformation when exposed to water, leading to uneven settlement or even tilting of superstructures. Traditional foundation reinforcement methods, such as pile foundation replacement or pressure grouting, while effective to some extent, suffer from problems such as complex construction, high costs, and significant environmental disturbance. Especially when existing buildings have softened due to water immersion, conventional methods are insufficient for achieving precise correction and in-situ reinforcement. Summary of the Invention

[0003] This application aims to at least partially solve one of the aforementioned technical problems in the prior art. To this end, embodiments of this application provide a method for reinforcing and correcting waterlogged, weak foundations in collapsible loess areas. This method effectively avoids secondary damage to buildings caused by large-scale excavation or dynamic compaction processes in traditional treatment methods, and has advantages such as convenient construction, minimal environmental impact, and low cost.

[0004] A method for reinforcing and correcting waterlogged, weak foundations in collapsible loess areas includes the following steps: The quicklime pile method was used to drain and reinforce the water source around the building to correct its course and to block and limit the spread of the flooded area. The free water in the immersion area of ​​the foundation of the building to be reinforced and corrected was drained using a lightweight wellpoint dewatering method. The settlement and tilt of the building to be reinforced were corrected by drilling and recharge water injection. After the quicklime piles have fully absorbed water and solidified, and the soil strength has reached the set requirements, the dewatering wells and recharge wells are backfilled and sealed. By burying moisture sensors and settlement observation points, data is collected regularly. When the settlement rate does not exceed 2 mm / month for three consecutive months and the moisture content fluctuation is less than 3%, the foundation is considered to have reached the stability standard.

[0005] In an optional or preferred embodiment, the quicklime pile method involves drilling holes around the building at designed intervals, inserting piles made of a mixture of quicklime and fly ash, utilizing the quicklime's strong water absorption to consume free water in the foundation, while simultaneously generating an expansion effect to compact the surrounding soil, increase soil strength, and form a waterproof curtain to block further infiltration of external water sources.

[0006] In an optional or preferred embodiment, the steps of the lightweight wellpoint dewatering method are as follows: lightweight wellpoint pipes are laid in the soil around the settlement area, and free water in the soil is continuously pumped out by a vacuum pump to lower the groundwater level, increase soil stress, and achieve preliminary consolidation.

[0007] In an optional or preferred embodiment, the borehole recharge water injection method is as follows: boreholes are drilled around the area with small settlement according to the designed hole spacing, and an appropriate amount of water is injected into the holes. By utilizing the characteristic of collapsible loess to compress when it comes into contact with water, the soil in the area is submerged and sinks, and the overall tilt of the building is gradually adjusted.

[0008] In optional or preferred embodiments, before implementing the quicklime pile method, the foundation of the building is first explored to determine the hydrogeology, immersion depth and range, and settlement and tilt of the building. Then, the water injection and recharge area and the precipitation area are delineated based on the exploration results.

[0009] In an optional or preferred embodiment, during the quicklime pile method, silicate cement is added to the quicklime pile, with the amount added being 5% to 10% of the mass of quicklime.

[0010] In optional or preferred embodiments, the material used for backfilling dewatering wells and recharge wells is early-strength cement slurry mixed with an expansion agent.

[0011] In optional or preferred embodiments, a segmented grouting process is adopted during backfilling, and the density is tested after each segment is grouted.

[0012] In an optional or preferred embodiment, a recyclable injection pipe is embedded in the injection hole of the borehole reinjection method.

[0013] In an optional or preferred embodiment, an automatic control device is used in the lightweight wellpoint dewatering process to dynamically adjust the pumping rate based on monitored groundwater level data.

[0014] Based on the above technical solution, the embodiments of this application have at least the following beneficial effects: This method is applicable to the treatment of foundation instability and building tilting caused by the infiltration of external water sources in collapsible loess. This technology effectively utilizes the physical properties of the soil itself, induces directional deformation of the foundation through moisture regulation, and improves the soil structure by using quicklime piles as a water-absorbing and consolidating material, thereby achieving the dual goals of correction and reinforcement, improving the overall safety and durability of the project, and having less disturbance to the superstructure, making it safer and more effective. It can effectively avoid secondary damage to the building caused by large-scale excavation or dynamic compaction in traditional treatment methods, and has the advantages of convenient construction, small environmental impact, and low cost. Attached Figure Description

[0015] The present application will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is a step diagram of a method for reinforcing and correcting a waterlogged, weak foundation in a collapsible loess area provided in an embodiment of this application; Figure 2 This is a schematic diagram of the water-inundated area around the foundation of the building in this application; Figure 3 This is a schematic diagram of quicklime piles driven around the foundation of the building in this application; Figure 4 This is a schematic diagram of dewatering wells and recharge wells around the foundation of the building in this application; Figure 5 It is Figure 4 A schematic diagram showing the backfilling of dewatering wells; Figure 6 It is Figure 4 The diagram shown illustrates the backfilling of the reinjection well. Detailed Implementation

[0016] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0017] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not 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 application.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0019] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0020] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0021] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0022] Collapsible loess exhibits high strength and low compressibility in its naturally dry state, but it is prone to significant collapsing deformation when exposed to water, leading to uneven settlement or even tilting of superstructures. Traditional foundation reinforcement methods, such as pile foundation replacement or pressure grouting, while effective to some extent, suffer from problems such as complex construction, high costs, and significant environmental disturbance. Especially when existing buildings have softened due to water immersion, conventional methods are insufficient for achieving precise correction and in-situ reinforcement.

[0023] Reference Figures 1 to 6 This application provides a method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas, comprising the following steps: The water source around building 1 was drained and reinforced using quicklime piles to correct its course and to block and limit the spread of water in the flooded area 2. The free water in the waterlogged area 2 of the foundation 3 of the building 1 to be reinforced and corrected was drained using a light wellpoint dewatering method; The settlement and tilt of the building 1 to be reinforced were corrected by drilling and recharge water injection. After the quicklime piles have fully absorbed water and solidified, and the soil strength has reached the set requirements, the dewatering well and the recharge well 7 will be backfilled and sealed. Moisture sensors 8 and settlement observation points are installed at the bottom of the building 1 to be corrected and reinforced. Data is collected regularly to determine whether the soil 4 around the building 1 to be corrected and reinforced is approaching a stable state. When the settlement rate does not exceed 2 mm / month for three consecutive months and the moisture content fluctuation is less than 3%, the foundation is considered to have reached the stability standard.

[0024] This method is applicable to the treatment of foundation instability and building tilting caused by external water infiltration in collapsible loess. This technology effectively utilizes the physical properties of the soil itself, induces directional deformation of the foundation through moisture regulation, and improves the soil structure by using quicklime piles as a water-absorbing consolidation material, thereby achieving the dual goals of correction and reinforcement, improving the overall safety and durability of the project, and causing less disturbance to the superstructure, making it safer and more effective. It can effectively avoid the secondary damage to the building caused by large-scale excavation or dynamic compaction in traditional treatment methods, and has the advantages of convenient construction, small environmental impact and low cost.

[0025] Among them, the building to be corrected and reinforced 1 is a building in a collapsible loess area where uneven settlement and tilting are caused by water immersion in the foundation; the building foundation 3 is the foundation of the building to be corrected and reinforced 1; the surrounding soil 4 is the natural soil outside the area surrounding the building foundation 3; the waterlogged area 2 around the building is the area where the foundation of the building to be corrected and reinforced and the surrounding soil 4 are soaked in water; the quicklime piles 5 are quicklime piles 5 driven around the surrounding soil 4 of the building, arranged in a quincunx pattern; the light dewatering wells 6 are light dewatering wells 6 driven between the quicklime piles 5 and the building foundation 3; the recharge wells 7 are recharge wells 7 driven between the quicklime piles 5 and the building foundation 3, arranged in the area with less settlement; and the monitoring points are the monitoring points arranged around the building for settlement and tilt observation.

[0026] The quicklime pile method involves drilling holes around the building at designed intervals, inserting piles made of a mixture of quicklime and fly ash, utilizing the quicklime's strong water absorption to consume free water in the foundation, while simultaneously generating an expansion effect to compact the surrounding soil, increase soil strength, and form a waterproof curtain to block further infiltration of external water sources.

[0027] The steps of the lightweight wellpoint dewatering method are as follows: lightweight wellpoint pipes are installed in the soil 4 surrounding the settlement area, and free water in the soil is continuously pumped out by a vacuum pump to lower the groundwater level, increase soil stress, and achieve preliminary consolidation.

[0028] The borehole recharge method involves drilling holes at the designed spacing around the area with minimal settlement, injecting an appropriate amount of water into the holes, and utilizing the compressibility of collapsible loess when it comes into contact with water to cause the soil in the area to subside and gradually adjust the overall tilt of the building.

[0029] The specific steps are as follows: S1. Explore the foundation of the building to determine the hydrogeology, water depth and range, and settlement and tilt of the building. Based on the exploration results, delineate the water injection and recharge area and the precipitation area, and clarify the location and depth of quicklime piles 5.

[0030] S2. The quicklime pile method drains water sources within the building foundation 3 and blocks and restricts the diffusion of water in the immersion area 2. Holes are drilled in the soil 4 around the building at the designed intervals, and piles made of quicklime and fly ash mixture are inserted. The strong water absorption of quicklime consumes the free water in the foundation, while the expansion effect compacts the surrounding soil, increases the soil strength and forms a waterproof curtain, effectively blocking the continued infiltration of external water sources. The hydration reaction of quicklime releases heat to promote soil drying and further improves the engineering performance of collapsible loess.

[0031] S3. Lightweight wellpoint dewatering method: This method drains free water within the immersion area of ​​the building foundation (section 3), reducing soil moisture content. Lightweight wellpoint pipes are installed around the settlement area, and vacuum pumps continuously extract free water from the soil, gradually lowering the groundwater level and increasing the effective stress in the soil, achieving initial consolidation. Moisture content changes are monitored simultaneously, and the dewatering rate is controlled to prevent further differential settlement. Once the soil moisture content reaches below the plastic limit, the next process is initiated.

[0032] S4. Borehole recharge and water injection for correction adjusts the settlement and tilt of the building. Boreholes are drilled at the designed spacing around areas with minimal settlement. A suitable amount of water is injected into the holes, utilizing the compressibility of collapsible loess when wet, causing the soil in that area to subside and gradually adjust the overall tilt of the building. The flow rate and rate of water injection are dynamically controlled based on real-time settlement monitoring data to ensure a smooth correction process. Water injection is stopped once the tilt rate meets the specifications, and a stabilization observation period begins.

[0033] S5. After the building foundation 3 is stable, the quicklime piles 5 have absorbed water and consolidated, and the dewatering wells and recharge wells 7 are backfilled, and after the quicklime piles 5 have fully absorbed water and consolidated, the soil strength has significantly improved and the foundation deformation has tended to stabilize, the dewatering wells and recharge wells 7 that have completed their mission are sealed, and low-flow, micro-expansion cement-based materials are used for backfilling to ensure that the structure is dense and without gaps.

[0034] S6. Continuously monitor soil moisture content and building settlement changes to verify the foundation reinforcement effect. By burying moisture content sensors and settlement observation points, long-term data collection and trend analysis are carried out to ensure the stability of the foundation during subsequent use.

[0035] In some embodiments, in step S2, an appropriate amount of silicate cement is added to the quicklime pile 5 to enhance its later strength and durability; the amount added is 5% to 10% of the mass of quicklime, which can promote early hydration reaction and form stable cementitious products in the later stage.

[0036] In some embodiments, during step S3, an automatic control device is used in the lightweight wellpoint dewatering process to dynamically adjust the pumping rate based on real-time monitored groundwater level data, so as to avoid additional settlement caused by sudden stress changes in the soil 4 due to excessively rapid dewatering.

[0037] In some embodiments, during step S4, a recyclable water injection pipe is installed inside the water injection hole to facilitate subsequent sealing operations. The water injection process adopts a phased, low-flow control mode, and the water injection volume of each hole is adjusted in real time according to the changes in building tilt to ensure that the correction process is controllable and to avoid local over-wetting that could cause new uneven settlement.

[0038] In some embodiments, in step S5, the backfill material is preferably an early-strength cement slurry incorporating an expansion agent. Its micro-expansion characteristics can effectively compensate for volume shrinkage during the sealing process, ensuring a tight bond between the well wall and the backfill. At the same time, a segmented grouting process is adopted, and the density is tested after each segment of grouting to ensure the sealing quality.

[0039] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A method for reinforcing and correcting the weak foundation of waterlogged loess in collapsible loess areas, characterized in that, Includes the following steps: The quicklime pile method was used to drain and reinforce the water source around the building to correct its course and to block and limit the spread of the flooded area. The free water in the immersion area of ​​the foundation of the building to be reinforced and corrected was drained using a lightweight wellpoint dewatering method. The settlement and tilt of the building to be reinforced were corrected by drilling and recharge water injection. After the quicklime piles have fully absorbed water and solidified, and the soil strength has reached the set requirements, the dewatering wells and recharge wells are backfilled and sealed. By burying moisture sensors and settlement observation points, data is collected regularly. When the settlement rate does not exceed 2 mm / month for three consecutive months and the moisture content fluctuation is less than 3%, the foundation is considered to have reached the stability standard.

2. The method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas according to claim 1, characterized in that: The steps of the quicklime pile method are as follows: drill holes around the building at the designed intervals, insert piles made of quicklime and fly ash mixture, utilize its strong water absorption to consume free water in the foundation, and at the same time generate an expansion effect to compact the surrounding soil, increase the soil strength and form a waterproof curtain to block the continued infiltration of external water sources.

3. The method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas according to claim 2, characterized in that: The steps of the lightweight wellpoint dewatering method are as follows: lightweight wellpoint pipes are laid in the soil around the settlement area, and free water in the soil is continuously pumped out by a vacuum pump to lower the groundwater level, increase soil stress, and achieve preliminary consolidation.

4. The method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas according to claim 3, characterized in that: The drilling and reinjection water method involves drilling holes at the designed spacing around the area with minimal settlement, injecting an appropriate amount of water into the holes, and utilizing the compressibility of collapsible loess when it comes into contact with water to cause the soil in the area to subside and gradually adjust the overall tilt of the building.

5. The method for reinforcing and correcting the weak foundation of waterlogged loess areas according to claim 1, characterized in that: Before implementing the quicklime pile method, the foundation of the building is first explored to determine the hydrogeology, water depth and range, and settlement and tilt of the building. Then, the water injection and recharge area and the precipitation area are delineated based on the exploration results.

6. The method for reinforcing and correcting the weak foundation of waterlogged loess areas according to claim 1, characterized in that: During the quicklime pile method, silicate cement is added to the quicklime pile, with the amount added being 5% to 10% of the mass of quicklime.

7. The method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas according to claim 1, characterized in that: The material used for backfilling dewatering wells and recharge wells is early-strength cement grout mixed with an expansion agent.

8. The method for reinforcing and correcting the weak foundation of waterlogged loess areas according to claim 7, characterized in that: The backfilling process adopts a segmented grouting process, and the density is tested after each segment is grouted.

9. The method for reinforcing and correcting the weak foundation of waterlogged loess areas according to claim 1, characterized in that: In the borehole recharge method, a recyclable injection pipe is installed inside the injection hole.

10. The method for reinforcing and correcting waterlogged and weak foundations in collapsible loess areas according to claim 1, characterized in that: The lightweight wellpoint dewatering method employs an automatic control device, which dynamically adjusts the pumping rate based on monitored groundwater level data.

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