A coordinated settlement drainage pipe and vacuum dewatering preloading method for soft soil foundation reinforcement

Abstract

The application discloses a drainage pipe suitable for soft soil foundation drainage consolidation and settlement deformation coordination and a vacuum drainage preloading reinforcement method, and the drainage pipe is composed of a plastic pipe core, a filter membrane and a plastic hose, the plastic pipe core comprises a spiral pipe core and an outer sleeve pipe core which are nested with each other, the outer side is wrapped with a water-permeable filter membrane, and the inside is provided with an elastic plastic hose. During construction, the bottom end of the drainage pipe is blocked, the drainage pipe is inserted into the soft soil foundation, the foundation is sealed, vacuum drainage is carried out after the vacuum equipment is connected, the vacuum pipe valve is closed at intervals, and dynamic drainage is carried out by using the pressure difference between the plastic hose and the vacuum pipe, so that the problems of large resistance, easy bending of the traditional drainage plate well and poor reinforcement effect of deep soil are solved. The application is adapted to the foundation settlement through the coordinated deformation of the double-layer pipe core, the drainage efficiency and the deep reinforcement effect are remarkably improved by combining the coordinated deformation of the elastic hose and the siphon effect, the application is suitable for the vacuum preloading and the stack preloading process, and the application has the advantages of convenient construction, low cost and strong adaptability.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, and relates to a method for reinforcing soft soil foundations, especially a method for reinforcing soft soil foundations by using the drainage pipe for vacuum dewatering preloading. Background Technology

[0002] Drainage consolidation is an economical and effective method for strengthening soft soil foundations. The most common approach in engineering is to install plastic drainage boards in the soft soil foundation followed by vacuum preloading or surcharge preloading. Traditional plastic drainage boards consist of a filter element and a filter membrane. The boards are relatively thin, approximately 3.5–5 mm thick, and the filter element is made of rigid plastic, lacking the ability to stretch or contract along its length. When inserted into the soft soil foundation, as the foundation settles and deforms, the drainage board, lacking the ability to deform, will twist, fold, or otherwise deform. This obstructs the drainage channels within the plastic drainage board, resulting in a significant well-resistance effect, which is detrimental to water drainage and vacuum transmission. The well-resistance effect and the bending of the drainage board due to foundation settlement further contribute to vacuum attenuation and reduced water flow, affecting the strengthening effect of the underlying foundation. Additionally, a high groundwater level also hinders foundation strengthening. Existing technologies offer a solution… CN 104005402A discloses a vacuum preloading consolidation drainage construction method. This method involves embedding multiple upper drainage pipes into a lower pipe boot to enter the silt layer, and then vacuuming the drainage pipes to reinforce the silt layer. During drainage, as the silt layer settles, the upper drainage pipes need to be repeatedly removed and replaced with pipes adapted to the height of the settled silt layer. While this method addresses the well obstruction and pipe folding problems of traditional drainage boards to some extent, the repeated replacement of upper drainage pipes to adapt to silt layer settlement is cumbersome, inefficient, and unsuitable for large-scale, high-settlement operations. This invention utilizes plastic drainage pipes that can adapt to the settlement and deformation of soft soil layers. The operation is simple, and the adaptability of the pipe core and drainage hose reduces unnecessary repetitive labor. It is particularly suitable for large-scale, high-settlement operations, solving the long-standing technical problem of poor deep soil reinforcement during vacuum preloading or surcharge preloading of soft soil foundations. It is applicable to both vacuum preloading and surcharge preloading. Summary of the Invention

[0003] In view of the problems and defects of the existing technology, the purpose of this invention is to provide a drainage pipe for drainage consolidation of soft soil foundations that can adapt to settlement and deformation, and a method for reinforcing soft soil foundations by using its vacuum dewatering preloading.

[0004] To achieve the above-mentioned technical objectives, this invention also provides a drainage pipe for drainage consolidation in soft soil foundations that can adapt to settlement and deformation, and a method for reinforcing soft soil foundations using vacuum dewatering preloading. The purpose of this invention is to solve the problems of high resistance and bending due to foundation settlement in traditional drainage slab wells. It addresses the issues of high compressibility and large settlement in soft soil layers, such as silty soil, fill soil, and coastal soft clay, which have high natural water content (often greater than the liquid limit), large void ratio (e>1.0), and low shear strength (cohesion c<10kPa). These layers are prone to significant settlement (settlement can reach 30% to 60% of the total depth) under external loads or their own gravity. Since the drainage pipe is designed with a maximum compression deformation of 3 / 5 to 2 / 3 times (relative displacement deformation of the spiral core relative to the outer core + compression deformation of the spiral core), it can effectively absorb the axial tensile or compressive stress generated during soft soil settlement, avoiding the problem of pipe breakage due to excessive deformation.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a settlement-coordinated drainage pipe for soft soil foundation reinforcement, comprising:

[0006] The spiral core and the outer core are provided. The spiral core includes a compressible spring structure composed of a spiral spring body, which has the ability to adapt to axial pressure and deform along the axial direction. The spiral core has cylindrical interfaces at both ends, and the outer surface of the cylindrical interfaces is provided with ribs. The outer core is a cylindrical structure with holes evenly distributed on the tube wall. The inner surface of the interfaces at both ends of the outer core is provided with ribs. The outer surfaces of the spiral core and the outer core are respectively covered with a water-permeable filter membrane.

[0007] The ribs at both ends of the spiral core and the outer core are evenly distributed in an alternating array along the circumference of the tube. The spiral core can be inserted by aligning one end of the rib with the gap between the ribs at one end of the outer core. After nesting and insertion, it is rotated to prevent slippage, forming a basic unit of the expandable and adjustable drainage pipe. Two or more of the basic units of the drainage pipe are nested and inserted into each other to form a drainage pipe to adapt to foundation settlement and deformation.

[0008] A plastic flexible hose is installed inside the drain pipe, hanging from the top to the bottom of the drain pipe. It can deform to accommodate the drain pipe and form an independent drainage channel.

[0009] Furthermore, the nested insertion end of the spiral core is molded with a silicone rubber wedge ring to increase the friction between the spiral core and the outer core, prevent random slippage, and ensure the sealing of the nested connection of the drain pipe.

[0010] Furthermore, the height of the molded silicone rubber wedge ring at the tube end is equal to the height of the reinforcing rib.

[0011] Furthermore, the spiral core is made of high-strength and high-density polyethylene, and the outer core is made of pressure-resistant high-density polyethylene.

[0012] Furthermore, the Poisson's ratio of the high-strength, high-density polyethylene material of the spiral core is 0.3.

[0013] Furthermore, the cross-section of the helical spring body is rectangular, and the width of the rectangle located on the outer side of the helical core is equal to the width of the helical spring gap, which is 1 / 2 of the pitch of the adjacent helical spring bodies, and the theoretical compression ratio can reach 50%.

[0014] Furthermore, the inner diameter of the outer sleeve core is at least 1.15 times the sum of the outer diameter of the spiral core and twice the thickness of the filter membrane.

[0015] Furthermore, the wall thickness of the helical spring body and the cylindrical interface tube is 3-5mm, and the wall thickness of the outer tube core is 1-3mm.

[0016] Furthermore, the height of the cylindrical interfaces at both ends of the spiral core is equal to the width of the spiral spring body.

[0017] Furthermore, the rib is in the shape of an isosceles trapezoid, and the height of the isosceles trapezoid is 0.075 times the sum of the outer diameter of the spiral core and twice the thickness of the filter membrane, so as to reserve sufficient space for the radial expansion generated when the spiral core is compressed.

[0018] Furthermore, the length of the outer sleeve core is 1 / 2 to 2 / 3 times the length of the spiral core core, so as to meet the maximum compression deformation of the drain pipe by 2 / 3 to 3 / 5 times.

[0019] Furthermore, the length of the drain pipe is 3 to 40 meters.

[0020] Furthermore, the plastic hose is made of elastic low-density polyethylene with a corrugated inner surface to accommodate settlement deformation and maintain unobstructed drainage.

[0021] Furthermore, the permeable filter membrane is a permeable geotextile.

[0022] Furthermore, the permeable geotextile is integrated with the spiral core or the outer core via a hot-melt process.

[0023] This invention provides a vacuum dewatering preloading method based on a coordinated settlement drainage pipe for soft soil foundation reinforcement, comprising the following steps:

[0024] S1. Based on the depth of the soft soil foundation and the expected settlement depth, select a reconcilable settlement drainage pipe with a length suitable for the expected settlement depth and within the depth of the soft soil foundation. The reconcilable settlement drainage pipe is a plastic drainage pipe.

[0025] S2. Seal the bottom of the plastic drainage pipe and insert the plastic drainage pipe into the soft soil foundation using drainage pipe installation equipment;

[0026] S3. Install the vacuum dewatering pre-compression process, connect the core of the drainage pipe to the vacuum pipe, and connect it to the vacuum equipment through the vacuum pipe valve. Connect the plastic hose to the upper plastic hose and connect it to the vacuum equipment.

[0027] S4. Turn on the vacuum equipment to create a vacuum;

[0028] S5. Close the vacuum tube valve intermittently and use the pressure difference between the upper plastic hose and the vacuum tube to dynamically drain water and accelerate foundation consolidation;

[0029] S6. The plastic drainage pipe coordinates with the settlement and deformation of soft soil, thus reinforcing the soft soil foundation.

[0030] Furthermore, the method for sealing the bottom of the plastic drain pipe in step S2 is as follows: a plastic sealing cap is nested into the bottom of the plastic drain pipe, and the insertion end of the plastic sealing cap has the same ribs as the bottom of the plastic drain pipe to facilitate nesting and insertion.

[0031] Furthermore, the insertion spacing of the plastic drainage pipes inserted into the soft soil foundation in step S2 is 0.7 to 1.3 m.

[0032] Furthermore, the vacuum dewatering preloading process described in step S3 includes the following steps:

[0033] S3a. Connect the cores of all plastic drain pipes to the filter pipe through a filter pipe tee, and connect the filter pipe to the vacuum tube; leave an opening at one end of the filter pipe tee inserted into the core, and connect the plastic hose to the upper plastic hose after passing through the opening;

[0034] S3b. Lay a sealing membrane on the surface of the soft soil foundation to form a sealed space. The vacuum tube and the upper plastic hose extend out of the sealing membrane and are connected to the vacuum equipment.

[0035] Furthermore, step S3 is the vacuum dewatering loading process, and there are additional loading process steps after step S3b:

[0036] S3c. Constructing a surcharge carrier on soft soil foundation to form a synergistic reinforcement of surcharge preloading and vacuum drainage.

[0037] Furthermore, in step S3a, the core of the plastic drainage pipe protrudes from the top surface of the foundation at a height of approximately 5 to 10 cm.

[0038] Furthermore, the orifice in step S3a is circular, which perfectly matches the shape and size of the plastic hose.

[0039] Furthermore, during the vacuum preloading process, the speed and effect of foundation consolidation are controlled by adjusting the vacuum level.

[0040] The main principles of this invention are as follows:

[0041] 1. Selection of spiral core material and Poisson's ratio:

[0042] Poisson's ratio (ν) is a key parameter that measures the ratio of transverse strain to axial strain of a material under uniaxial tension or compression (ν = |transverse strain / axial strain|). Its influence on the inner diameter of a helical expandable tube is mainly reflected in the following aspects:

[0043] 1) Direct relationship between Poisson's ratio and transverse strain

[0044] When the helical core is axially compressed, a compressive strain (ε_longitudinal, negative) is generated in the longitudinal direction. According to the Poisson effect, a reverse positive strain (ε_lateral = ν × |ε_longitudinal|) is generated in the transverse (radial) direction.

[0045] 2) The magnitude of Poisson's ratio determines the range of change in inner diameter.

[0046] A higher Poisson's ratio results in a higher ratio of transverse strain to longitudinal strain, more significant radial expansion, and a greater variation in inner diameter. For example:

[0047] If high-density polyethylene (HDPE) with a Poisson's ratio of 0.46 (upper limit) is used, the transverse strain is 0.46 × 0.5 = 0.23, the radial expansion is 23%, and the inner diameter change is the largest.

[0048] If high-density polyethylene (HDPE) with a Poisson's ratio of 0.3 (lower limit) is used, the transverse strain is 0.3 × 0.5 = 0.15, the radial expansion is 15%, and the change in inner diameter is minimal.

[0049] Poisson's ratio directly determines the degree of radial expansion when a helical core is axially compressed. The larger the value, the more significant the lateral strain (radial expansion) and the greater the change (shrinkage) in the inner diameter; conversely, the smaller the Poisson's ratio, the slighter the change in inner diameter. This rule is directly determined by the definition of Poisson's ratio (the ratio of lateral strain to axial strain).

[0050] Choose high-density polyethylene (HDPE) with a Poisson's ratio of 0.3, which means choosing high-density polyethylene (HDPE) with the least radial expansion;

[0051] 3) Selection of spiral core material

[0052] To improve the stiffness coefficient and compressive strength of the spiral core, high-strength and high-toughness high-density polyethylene should be selected as the material to enhance the axial / transverse compressive strength of the spiral core body, such as high-density polyethylene-metallocene polyethylene composite material (HDPE-mPE):

[0053] The addition of mPE increases the elongation at break of the material and enhances the flexibility of the molecular chains. When subjected to external forces, it can undergo greater deformation and recover its original shape to a certain extent. Therefore, its elasticity is better than that of spring coils made of ordinary HDPE.

[0054] Axial compressive strength: The addition of mPE improves the tensile strength and impact strength of the material, enabling it to withstand greater pressure without fracture or permanent deformation under axial compression. Simultaneously, the higher molecular structure regularity and crystallinity of mPE further enhance its resistance to deformation under axial pressure.

[0055] Lateral compressive strength: The compressive strength of the material is also improved under lateral compression. The addition of mPE strengthens the intermolecular forces of HDPE, making it more difficult for the molecular chains to slide, thereby improving the material's resistance to deformation under lateral pressure.

[0056] 2. Matching of the outer diameter of the spiral inner core and the inner diameter of the outer sleeve core:

[0057] 1) Deformation characteristics of high-density polyethylene (HDPE) materials

[0058] High-density polyethylene (HDPE) is a tough material (Poisson's ratio ν≈0.3-0.4). When the spiral core is axially compressed by 50%, according to the Poisson effect, a normal strain will be generated in the transverse (radial) direction (ε_transverse = -ν·ε_longitudinal). Since the longitudinal strain is -0.5 (compression of 50%), the transverse strain is ε_transverse = 0.3 × 0.5 = 0.15 (i.e., radial expansion of about 15%).

[0059] 2) Design logic of outer tube inner diameter

[0060] Natural unfolding state: The outer diameter of the spiral core is D, and the inner diameter of the outer core needs to be slightly larger than D to ensure nesting;

[0061] Compression state: The radial expansion of high-density polyethylene (HDPE) causes the outer diameter of the spiral core to increase to D'≈D×(1+ε_transverse)=1.15D. Therefore, the inner diameter of the outer core must be at least equal to the maximum outer diameter of the spiral core after compression, 1.15D, to avoid jamming during compression.

[0062] In summary, the inner diameter of the outer tube core should be designed to be at least 1.15D to simultaneously meet the requirements of nesting and a theoretical compression ratio of 50%.

[0063] 3. The length ratio of the outer casing core to the spiral core and the range of settlement deformation it can adapt to:

[0064] If the length of the outer core is half the length of the helical core, and the relative displacement range between the helical core and the outer core is one-third of the pipe length, it can adapt to soft soil foundations with a settlement of 30%, which falls within the range of most natural soft soil foundations. When the foundation settlement exceeds 30%, the relative displacement of the helical core extends into the outer core, and the helical cores connect end to end in the inner rings. At this point, the settlement deformation force is relatively large, and the helical core begins to compress and deform under the settlement pressure. Under the ultimate pressure, the helical core is completely compressed into the outer core. At this point, the drainage pipe forms a two-ring structure, and the compressive strength of the drainage pipe is also enhanced, allowing it to adapt to greater pressure on soft soil foundations. Theoretically, it can adapt to soft soil foundations with a settlement of up to two-thirds.

[0065] If the length of the outer core is 2 / 3 of the length of the spiral core, it can adapt to soft soil foundations with a settlement of 40%, which falls within the range of most natural soft soil foundations. When the foundation settlement exceeds 40%, the spiral core is relatively displaced into the inner core of the outer core. The spiral cores are connected end to end in the inner ring. At this time, the settlement deformation force is relatively large, and the spiral core begins to compress and deform under the settlement pressure. Under the ultimate pressure, the spiral core is completely compressed into the inner core of the outer core. At this time, the drainage pipe forms a two-ring structure, and the compressive strength of the drainage pipe is also enhanced, which can adapt to greater pressure on soft soil foundations. Theoretically, it can adapt to soft soil foundations with a settlement of up to 3 / 5.

[0066] 4. The function of adding ribs:

[0067] The inner diameter of the outer core should be at least 1.15 times the outer diameter of the spiral core (the filter membrane thickness needs to be considered). Due to this constraint, the height of the rib at the end of the spiral core should be half the sum of 0.15 times the outer diameter of the spiral core and twice the filter membrane thickness, i.e., 0.075 times the sum of the outer diameter of the spiral core and twice the filter membrane thickness. For example, if the outer diameter of the spiral core is 19mm and the filter membrane thickness is 0.5mm, then the height or radius of the rib should be designed as: 0.075 * 20 = 1.5mm, which can accommodate the radial expansion after compression of the spiral core. If the outer diameter of the spiral core is 29mm and the filter membrane thickness is 0.5mm, then the height or radius of the rib should be designed as: 0.075 * 30 = 2.25mm, which can accommodate the radial expansion after compression of the spiral core.

[0068] The reinforcing ribs are evenly and alternately distributed along the outer surface of the cylindrical interface at the end of the spiral tube core (the inner surface of the end of the outer tube core) in the form of reinforcing ribs, reinforcing rib gaps, reinforcing ribs, reinforcing rib gaps... The width of the reinforcing rib gaps is greater than or equal to the width of the reinforcing ribs. The spiral tube core is selected at a certain angle relative to the outer tube core so that the reinforcing ribs of the spiral tube core are exactly aligned with the reinforcing rib gaps between the reinforcing ribs of the outer tube core. The spiral tube core can be inserted into the outer tube core, and then rotated back to the corresponding position of the reinforcing ribs to prevent the spiral tube core from slipping off relative to the outer tube core.

[0069] The ribs are semi-circular or isosceles trapezoidal. Their functions are: first, to provide sufficient space for the radial expansion of the spiral core; second, to enhance the compressive strength of the tube; and third, to limit the spiral core and the outer tube core, so that the spiral core is not easily slipped out after being inserted into the outer tube core due to the obstruction of the ribs.

[0070] 5. Intermittent vacuuming and siphon effect:

[0071] During intermittent vacuuming, the anti-clogging design of the corrugated plastic hose ensures the continuous unobstructed flow of water, preventing the siphon from being interrupted due to blockage. At the same time, the spring-type telescopic structure of the spiral core can resonate with the intermittent vacuuming, effectively promoting the generation of the siphon effect and maintaining its continuity.

[0072] When a compressible spring core (spiral core) is intermittently evacuated, the axial contraction due to the negative pressure of the vacuum causes the internal space to dynamically shrink, further reducing the local pressure. Meanwhile, the corrugated shape of the internal plastic hose creates alternating peaks and troughs during vacuuming, forming localized high-speed flow regions that accelerate water flow towards the negative pressure zone. The synergy between these two factors—the spring core contraction leading to a sudden drop in internal pressure and the corrugated tube's drainage effect leading to accelerated water flow—significantly enhances the negative pressure gradient within the tube, providing a continuous driving force for the siphon effect.

[0073] 6. The principle of the plastic drainage pipe of the present invention in coordinating with foundation settlement and deformation:

[0074] The purpose of soft soil foundation reinforcement is to drain water from the soil, thereby improving its mechanical properties. During the reinforcement process, as water is drained, the soil volume decreases, leading to foundation settlement. The compressive settlement of saturated soft soil can be calculated using the soil's physical properties before and after reinforcement: compressibility.

[0075] w1 and w2 represent the water content before and after treatment, and G sThis refers to the specific gravity of soil particles. The water content of natural soft soil layers is approximately 50-80%, and the compression rate of the soil after reinforcement is approximately 10%-30%. In some coastal, lake, and river tidal flats, the settlement of high-water-content silty soft soil layers can reach 30%-60%. The plastic drainage pipe of this invention can achieve a maximum coordinated deformation of 3 / 5 to 2 / 3, breaking through the 50% maximum deformation limit of traditional drainage pipes. When the plastic drainage pipe of this invention is inserted into a soft soil foundation, the soft soil foundation exerts lateral pressure on the plastic drainage pipe. During the reinforcement process of the soft soil, compression deformation occurs, which generates lateral friction resistance on the plastic drainage pipe. The spiral core and the outer core are subjected to lateral friction resistance in opposite directions. Because the spiral core is inserted into the outer core, and the insertion resistance is relatively small, the spiral core and the outer core immediately undergo relative displacement, increasing the insertion depth until the spiral core is connected end-to-end. Coordination begins through the compression deformation of the spiral core itself, and finally, the spiral core completely enters the interior of the outer core, while the flexible hose inside the core is coordinated through bending.

[0076] 7. The principle of reducing well resistance using the plastic drainage pipe of this invention:

[0077] Well resistance refers to the resistance encountered by water flowing outward from the drainage channel during the consolidation process of soft clay foundations. Plastic drainage boards are typically 10cm wide and 3.5-5mm thick. After deducting the cross-sectional area of ​​the core, their water-passing cross-section is basically the same as that of the plastic drainage pipe of this invention. Because the core of the plastic drainage board divides the water-passing cross-section into several rectangles, the contact area between the drainage board and the water is large, resulting in high resistance. The plastic drainage pipe of this invention has a small contact area between the water flow and the pipe body, thus reducing resistance. Bending and twisting of the plastic drainage board during foundation reinforcement can cause significant well resistance. The plastic drainage pipe of this invention can coordinate with foundation settlement through its own expansion and contraction deformation; the drainage channel will not bend or twist, meaning that significant well resistance will not occur due to foundation settlement during foundation reinforcement. The well resistance factor is considered in the formula for calculating the degree of consolidation of soft soil in the "Technical Specification for Application of Plastic Drainage Boards in Water Transport Engineering," and the formula is as follows:

[0078] , where q h q represents the amount of water that seeps into the drainage board. w F represents the longitudinal water flow rate of the drainage board. s To account for the well resistance effect, a safety factor is required, which is related to the depth. L is the length of the drainage board, and d... w This is the converted diameter of the drainage board. A higher well resistance factor indicates lower consolidation. The plastic drainage pipe of this invention can adapt to settlement deformation in the depth direction without bending or twisting. The drainage channel cross-section remains consistent and is unaffected by the foundation reinforcement depth, significantly reducing F... s This reduces the well resistance factor G, and under the same conditions, greatly improves the degree of soil consolidation.

[0079] The beneficial effects of this invention are mainly reflected in the following aspects:

[0080] 1. Significantly Improved Soft Soil Foundation Reinforcement: By employing plastic drainage pipes that can coordinate with settlement deformation and combining them with vacuum dewatering preloading construction technology, the problem of poor reinforcement effects in deep soft soil layers in traditional methods can be effectively solved. When the soft soil layer settles, the plastic drainage pipes can deform in coordination with it, ensuring that the drainage pipes maintain good working condition throughout the entire reinforcement process. This allows water and air in the soft soil layer to drain smoothly, and also lowers the groundwater level of the site, thereby achieving efficient consolidation and reinforcement of the soft soil foundation and significantly improving the bearing capacity and stability of the foundation.

[0081] 2. Effectively avoids drainage pipe damage and drainage obstruction: Traditional drainage boards suffer from high well resistance and bending due to foundation settlement, leading to reduced drainage and vacuum pumping effects. The plastic drainage pipe of this invention has excellent flexibility and adaptability, capable of adapting to the settlement and deformation of soft soil layers. This avoids damage, blockage, or bending of the drainage pipe caused by foundation settlement, ensuring that the drainage pipe remains unobstructed throughout the entire construction process and subsequent use, maintaining a stable drainage effect. This, in turn, guarantees the smooth progress of vacuum preloading or surcharge preloading construction, improving construction efficiency and quality.

[0082] 3. Enhanced Construction Adaptability and Reliability: The plastic drainage pipes of this invention can be flexibly laid out at predetermined intervals according to the specific conditions of soft soil foundations, exhibiting strong construction adaptability. Simultaneously, its connection method with vacuum equipment is simple and reliable, and operation is convenient. It can seamlessly integrate with existing vacuum dewatering preloading construction processes without requiring large-scale modifications to existing construction equipment and processes, reducing construction costs and difficulty, and improving the feasibility and reliability of construction. It is suitable for various soft soil foundation reinforcement projects and has broad application value.

[0083] 4. Reduce labor costs and improve labor efficiency: The method of this invention uses plastic drainage pipes that can adapt to the settlement and deformation of soft soil layers. The operation method is simple. By adapting the pipe core to the settlement of soft soil layers and the adaptive changes of the drainage hose, unnecessary repetitive labor is reduced. It can adapt to large-scale and large settlement operations, thereby reducing labor costs and significantly improving labor efficiency.

[0084] 5. Covers over 90% of soft soil settlement: The combined design of the displacement and expansion deformation of the spiral core relative to the outer core and the compression deformation of the spiral core itself can cover over 90% of soft soil settlement scenarios, avoiding frequent replacement or maintenance and improving the long-term stability of the drainage system. Attached Figure Description

[0085] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. They are used together with the embodiments of this invention to explain this invention and do not constitute a limitation of this invention.

[0086] Figure 1 Cross-sectional views of the drainage pipes in Embodiments 1-3 of the present invention.

[0087] Figure 2 : AA cross-sectional view of the drainage pipe in Embodiments 1-3 of the present invention.

[0088] Figure 3 : A three-dimensional front view of the spiral core of the drainage pipe in Embodiments 1-3 of the present invention.

[0089] Figure 4 Cross-sectional views of the outer casing core of the drainage pipe in Embodiments 1-3 of the present invention.

[0090] Figure 5 The core state of the drainage pipe before deformation in Embodiments 1-3 of the present invention.

[0091] Figure 6 The core state of the drainage pipe after deformation in Embodiments 1-3 of the present invention.

[0092] Figure 7 : Cross-sectional view of the plastic sealing cap used in the vacuum dewatering preloading method of this invention.

[0093] Figure 8 : Schematic diagram of the drainage pipe connected to the three-way filter pipe in the vacuum dewatering preloading and surcharge preloading method of the present invention.

[0094] Figure 9 : Schematic diagram of the vacuum precipitation preloading reinforcement method of the present invention.

[0095] Figure 10 : Schematic diagram of the vacuum precipitation preloading reinforcement method of the present invention.

[0096] Figure 11 : Flowchart of the operation steps of the soft soil foundation reinforcement method of the present invention.

[0097] In the diagram: 1. Plastic hose; 2. Spiral core; 3. Filter membrane; 4. Outer core; 5. Tube wall; 6. Hole; 7. Rib; 8. Rib gap; 9. Filter tube tee; 10. Filter tube; 11. Vacuum tube; 12. Upper plastic hose; 13. Sealing membrane; 14. Plastic drain pipe; 15. Plastic hose valve; 16. Vacuum tube valve; 17. Vacuum equipment; 18. Earth cofferdam; 19. Stacking carrier; 20. Plastic sealing cap; 21. Helical spring body; 22. Helical spring gap; 23. Silicone rubber wedge ring; 24. Cylindrical interface. Detailed Implementation

[0098] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0099] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0100] This invention provides a drainage pipe for drainage consolidation in soft soil foundations that can adapt to settlement and deformation. By inserting the plastic drainage pipe into the soft soil foundation at predetermined intervals, implementing a vacuum preloading construction process, and connecting it to a vacuum device, the vacuum device is activated to expel water and air from the soft soil layer. This causes the soft soil layer to settle, and the plastic drainage pipe deforms in accordance with this settlement, thereby achieving the technical objective of consolidating and reinforcing the soft soil foundation. The technical solution of this invention solves the problems of high resistance and bending due to foundation settlement in traditional drainage wells, the inability of drainage pipes to adapt to settlement in soft soil layers, and the corresponding decrease in drainage and vacuuming efficiency. It also addresses the long-standing technical problem of poor deep soil reinforcement during vacuum preloading or surcharge preloading of soft soil foundations.

[0101] Example 1 provides a settlement-coordinated drainage pipe for soft soil foundation reinforcement. In Example 1, the plastic drainage pipe of the present invention can adapt to soft soil foundations with an expected settlement range of less than 2m and a depth of more than 3m. Figure 1As shown, the drain pipe 14 consists of a core, a filter membrane 3, and a plastic hose 1. The core is made of pressure-resistant high-density polyethylene, ensuring that the ring stiffness of the plastic drain pipe is greater than 8 kN / m. 2 The plastic core is divided into a spiral core 2 and an outer core 4, such as Figure 3 As shown, the main body of the spiral core 2 is a spiral spring structure, made of high-strength, high-density polyethylene with a Poisson's ratio of 0.3. The cross-section of the spiral spring body 21 is rectangular, and the width of the outer side of the rectangle is equal to the width of the spiral spring gap 22, which is half the pitch of the adjacent spiral spring bodies 21. The theoretical compression ratio can reach 50%. The length is about 100mm, the outer diameter of the spiral core 2 is about 19mm, and the thickness of the spiral spring body 21 is about 3mm. Both ends of the spiral core 2 are cylindrical interfaces 24. The height of the cylindrical interfaces 24 is equal to the width of the spiral spring body 21. Ribs 7 are evenly arranged along the circumference of the outer surface of the cylindrical interfaces 24. Figure 2 As shown, the reinforcing rib 7 is an isosceles trapezoid with a height of approximately 1.5 mm. The reinforcing ribs are evenly distributed in an array on the outer surface of the cylindrical interface 24, with ribs 7, rib gaps 8, ribs 7, rib gaps 8... The width of the rib gaps 8 is greater than or equal to the width of the ribs 7. A silicone rubber wedge-shaped ring 23, molded to the same height as the reinforcing ribs 7, is inserted into the nested insertion end of the spiral core 2 to increase the friction between the spiral core 2 and the outer core 4, preventing random slippage and ensuring the sealing of the drain pipe nested connection. Figure 4 As shown, the outer tube core 4 is cylindrical, approximately 50mm long and 24mm in inner diameter. The tube wall 5 is approximately 1mm thick, and several holes 6, each approximately 3mm in diameter, are arranged on the tube wall 5. The area of ​​the holes 6 accounts for 30%–50% of the total area. Ribs 7 are evenly distributed along the circumference of the inner surface of both ends of the tube wall 5 of the outer tube core 4. The ribs 7 are isosceles trapezoids in shape and approximately 1.5mm high. These ribs facilitate the nesting combination between the spiral core 2 and the outer tube core 4. The height of the ribs 7 is 0.075 times the sum of the outer diameter of the spiral core 2 and twice the thickness of the filter membrane, providing sufficient space for radial expansion during compression of the spiral core 2. Figure 3 , Figure 4 As shown, a filter membrane 3 is wrapped around the outside of the holes 6 of the outer core 4 and the helical spring gap 22 of the helical core 2. The filter membrane 3 is a geotextile with permeability, corrosion resistance and tensile strength, such as... Figure 5As shown, the spiral core 2 is inserted into the outer core 4 to form a basic drainage pipe unit approximately 150mm long. Twenty of these basic drainage pipe units are nested together to form a plastic drainage pipe 14, approximately 3m long, suitable for coordinating settlement in soft soil foundation reinforcement. A plastic flexible hose 1 is installed in the middle of the plastic drainage pipe 14. The plastic flexible hose 1 is a circular hose with a diameter of 6mm and a wall thickness of 1mm, made of elastic, low-density polyethylene. The plastic flexible hose 1 extends from the top of the plastic drainage pipe 14 to the bottom, approximately 0.5m from the bottom. During foundation settlement, if… Figure 6 As shown, the spiral core 2 can adapt to the settlement of the soft soil layer and enters the outer core 4, as... Figure 7 As shown, the plastic hose 1 gradually sinks to the bottom as the foundation settles. When the foundation settlement exceeds 0.5m, the plastic hose 1 bends and deforms. The inner surface of the plastic hose has a corrugated structure, yet it still maintains good water permeability. This case is more suitable for foundations with high compressibility, such as the reinforcement of soft soil foundations filled by hydraulic filling.

[0102] Example 2 provides a settlement-coordinated drainage pipe for soft soil foundation reinforcement. In Example 2, the plastic drainage pipe of the present invention can adapt to soft soil foundations with an expected settlement range of less than 9m and a depth of more than 15m. Figure 1 , Figure 2 As shown, the plastic drain pipe 14 consists of a plastic core, a filter membrane 3, and a plastic hose 1. The plastic core is divided into a spiral core 2 and an outer core 4, as shown... Figure 3 As shown, the main body of the spiral core 2 is a spiral spring structure, made of high-strength, high-density polyethylene with a Poisson's ratio of 0.3. The cross-section of the spiral spring body 21 is rectangular. The width of the rectangle on the outer side of the spiral core is equal to the width of the spiral spring gap 22, which is half the pitch of the adjacent spiral spring bodies 21. The theoretical compression ratio can reach 50%. The spiral core 2 is approximately 300mm long, approximately 19mm in outer diameter, and approximately 4mm thick. Both ends of the spiral core 2 are cylindrical interfaces 24. The height of the cylindrical interfaces 24 is equal to the width of the spiral spring body 21. Ribs 7 are evenly arranged along the circumference of the outer surface of the cylindrical interfaces 24. Figure 2 As shown, the reinforcing rib 7 is an isosceles trapezoid with a height of approximately 1.5 mm. The reinforcing ribs are evenly distributed in an array on the outer surface of the cylindrical interface 24, with ribs 7, rib gaps 8, ribs 7, rib gaps 8... The width of the rib gaps 8 is greater than or equal to the width of the ribs 7. A silicone rubber wedge-shaped ring 23, molded to the same height as the reinforcing ribs 7, is inserted into the nested insertion end of the spiral core 2 to increase the friction between the spiral core 2 and the outer core 4, preventing random slippage and ensuring the sealing of the drain pipe nested connection. Figure 4As shown, the outer tube core 4 is cylindrical, approximately 200mm long, with an inner diameter of approximately 23mm. The tube wall 5 is approximately 2mm thick, and several holes 6 with a diameter of approximately 3mm are arranged on the tube wall 5. The area of ​​the holes 6 accounts for 30% to 50%. Ribs 7 are evenly distributed along the circumference of the inner surface of both ends of the tube wall 5 of the outer tube core 4. The ribs 7 are isosceles trapezoids with a height of approximately 1.5mm. The ribs facilitate the nesting combination between the spiral tube core 2 and the outer tube core 4. The height of the ribs 7 is 0.075 times the sum of the outer diameter of the spiral tube core 2 and twice the thickness of the filter membrane, reserving sufficient space for the radial expansion generated when the spiral tube core 2 is compressed. Figure 3 , Figure 4 As shown, a filter membrane 3 is wrapped around the outside of the holes 6 of the outer tube core 4 and the helical spring gap 22 of the spiral tube core 2. The filter membrane 3 is a geotextile with permeability, corrosion resistance and tensile strength. The filter membrane 3 is thermally fused to the spiral tube core 2 or the outer tube core 4 respectively. Figure 5 As shown, the spiral core 2 is inserted into the outer core 4 to form a basic drainage pipe unit approximately 500mm long. These 30 basic drainage pipe units are nested together to form a plastic drainage pipe 14, approximately 15m long, suitable for coordinating settlement in soft soil foundation reinforcement. A flexible plastic hose 1 is installed in the middle of the plastic drainage pipe 14. The flexible plastic hose 1 is a corrugated inner surface plastic hose with a diameter of 6mm, a wall thickness of 1mm, and is made of elastic, low-density polyethylene. The flexible plastic hose 1 extends from the top of the plastic drainage pipe 14 to the bottom, approximately 2m from the bottom. During foundation settlement, if… Figure 6 As shown, the spiral core 2 can adapt to the settlement of the soft soil layer and enters the outer core 4, as... Figure 7 As shown, the plastic hose 1 gradually sinks to the bottom as the foundation settlement increases. When the foundation settlement exceeds 2m, the plastic hose 1 bends and deforms. The inner surface of the plastic hose has a corrugated structure, yet it still maintains good water permeability. This case is more suitable for foundations with high compressibility, such as the reinforcement of soft soil foundations filled by hydraulic filling.

[0103] Example 3 provides a settlement-coordinated drainage pipe for soft soil foundation reinforcement. In Example 3, the plastic drainage pipe of the present invention can adapt to soft soil foundations with an expected settlement range of less than 24m and a depth of more than 40m. Figure 1 As shown, the plastic drain pipe 14 consists of a plastic core, a filter membrane 3, and a plastic hose 1. The plastic core is divided into a spiral core 2 and an outer core 4, as shown... Figure 3As shown, the main body of the spiral core 2 is a spiral spring structure, made of high-strength, high-density polyethylene with a Poisson's ratio of 0.3. The cross-section of the spiral spring body 21 is rectangular. The width of the rectangle on the outer side of the spiral core is equal to the width of the spiral spring gap 22, which is half the pitch of the adjacent spiral spring bodies 21. The theoretical compression ratio can reach 50%. The spiral core 2 is about 1.5m long and about 29mm in outer diameter. The spiral spring body 21 is about 5mm thick. Both ends of the spiral core 2 are cylindrical interfaces 24. The height of the cylindrical interfaces 24 is equal to the width of the spiral spring body 21. Ribs 7 are evenly arranged along the circumference of the outer surface of the cylindrical interfaces 24. Figure 2 As shown, the reinforcing rib 7 is an isosceles trapezoid with a height of approximately 1.5 mm. The reinforcing ribs are evenly distributed in an array on the outer surface of the cylindrical interface 24, with ribs 7, rib gaps 8, ribs 7, rib gaps 8... The width of the rib gaps 8 is greater than or equal to the width of the ribs 7. A silicone rubber wedge-shaped ring 23, molded to the same height as the reinforcing ribs 7, is inserted into the nested insertion end of the spiral core 2 to increase the friction between the spiral core 2 and the outer core 4, preventing random slippage and ensuring the sealing of the drain pipe nested connection. Figure 4 As shown, the outer tube core 4 is cylindrical, approximately 1m long, with an inner diameter of approximately 34.5mm. The tube wall 5 is approximately 3mm thick, and several holes 6 with a diameter of approximately 3mm are arranged on the tube wall 5. The area of ​​the holes 6 accounts for 30% to 50%. Ribs 7 are evenly distributed along the circumference of the inner surface of both ends of the tube wall 5 of the outer tube core 4. The ribs 7 are isosceles trapezoids with a height of approximately 2.25mm. The ribs 7 facilitate the nesting combination between the spiral tube core 2 and the outer tube core 4. The height of the ribs 7 is 0.075 times the sum of the outer diameter of the spiral tube core 2 and twice the thickness of the filter membrane, reserving sufficient space for the radial expansion generated when the spiral tube core 2 is compressed. Figure 3 , Figure 4 As shown, a filter membrane 3 is wrapped around the outside of the holes 6 of the outer tube core 4 and the helical spring gap 22 of the spiral tube core 2. The filter membrane 3 is a geotextile with permeability, corrosion resistance and tensile strength. The filter membrane 3 is thermally fused to the spiral tube core 2 or the outer tube core 4 respectively. Figure 5 As shown, the spiral core 2 is inserted into the outer core 4 to form a basic drainage pipe unit approximately 2.5m long. Sixteen of these basic drainage pipe units are nested together to form a plastic drainage pipe 14, approximately 40m long, suitable for coordinating settlement in soft soil foundation reinforcement. A flexible plastic hose 1 is installed in the middle of the plastic drainage pipe 14. The flexible plastic hose 1 is a corrugated inner surface plastic hose with a diameter of 6mm, a wall thickness of 1mm, and is made of elastic, low-density polyethylene. The flexible plastic hose 1 extends from the top of the plastic drainage pipe 14 to the bottom, approximately 5m from the bottom. During foundation settlement, if… Figure 6 As shown, the spiral core 2 can adapt to the settlement of the soft soil layer and enters the outer core 4, as... Figure 7As shown, the plastic hose 1 gradually sinks to the bottom as the foundation settlement increases. When the foundation settlement exceeds 5m, the plastic hose 1 bends and deforms. The inner surface of the plastic hose has a corrugated structure, yet it still maintains good water permeability. This case is more suitable for foundations with high compressibility, such as the reinforcement of soft soil foundations filled by hydraulic filling.

[0104] A method for vacuum dewatering preloading reinforcement using any of the drainage pipes described in Examples 1-3 is disclosed. The method involves sealing the bottom end of the aforementioned plastic drainage pipe 14 on a soft soil foundation. A plastic drainage pipe installation device is used to fix the sealed plastic drainage pipe 14 to the nozzle of the device. The device utilizes gravity and vibration to insert the nozzle, along with the plastic drainage pipe 14, into the soft soil foundation through a long steel pipe. After reaching the required depth, the long steel pipe and nozzle are pulled out, leaving the plastic drainage pipe 14 in the foundation. The plastic drainage pipes 14 are inserted into the soft soil foundation at certain intervals (0.7–1.3 m), with the insertion depth being the required reinforcement depth. Based on engineering experience, the reinforcement depth using this method is approximately 3 m to 40 m. The plastic drainage pipe 14 protrudes about 5cm from the top surface of the foundation. The top cores of all the plastic drainage pipes 14 are connected to the filter pipe 10, and the filter pipe 10 is connected to the vacuum pipe 11. The tops of all the plastic hoses 1 are connected to the upper plastic hose 12 through connectors. A sealing membrane 13 is laid on the foundation to isolate the foundation to be reinforced from the outside air. The vacuum pipe 11 and the upper plastic hose 12 extend out of the sealing membrane 13. The vacuum pipe 11 and the upper plastic hose 12 are connected to the vacuum equipment 17 and each is equipped with a valve. The vacuum equipment 17 is turned on to draw a vacuum. The water and air in the foundation are gradually extracted, the soft soil is consolidated, and the foundation settles. The plastic drainage pipes 14 buried in the soft soil foundation coordinate the foundation settlement deformation through the insertion depth of the spiral core 2 into the outer core 4, ensuring that the plastic drainage pipes 14 are always in a good state of water flow and vacuum transmission. As the water in the foundation is continuously drained, according to the consolidation theory, the consolidation becomes increasingly slow. The water in the plastic drainage pipe 14 needs to be full before it can be pumped out. When the water in the plastic drainage pipe 14 cannot be pumped out temporarily, the water in the pipe exerts pressure on the soft soil foundation, which is not conducive to the drainage and consolidation of the soft soil foundation. At this time, we intermittently close the vacuum pipe valve 16 connected to the vacuum device 17. When the vacuum pipe valve 16 is closed, the vacuum degree in the plastic drainage pipe 14 will gradually decrease, while the vacuum degree in the plastic hose 1 will not decrease. The water in the plastic drainage pipe 14 is pumped out through the plastic hose 1 under the action of pressure difference. The spiral core 2 begins to expand and contract under the dual action of soft soil settlement pressure and vacuum pressure. Together with the corrugated structure of the plastic hose 1, it promotes the formation of the siphon effect. At this time, the water level of the foundation drops, the effective stress of the soft soil foundation increases, and the reinforcement effect of the soft soil foundation is improved.

[0105] A reinforcement method for vacuum dewatering surcharge preloading using any of the drainage pipes in Examples 1-3 is described below. The first method is also applicable. Details are provided below for different applications, such as... Figure 10 As shown, a drainage cushion layer is first laid on the soft soil foundation. The bottom end of the aforementioned plastic drainage pipe 14 is then sealed, and the pipes are inserted into the soft soil foundation at certain intervals (0.7–1.3 m). The insertion depth is the depth required for reinforcement in the project. Based on engineering experience, the reinforcement depth using this method is approximately 3 m to 40 m. The plastic drainage pipe 14 protrudes about 5 cm above the top surface of the foundation. Figure 8 As shown, the top cores of all plastic drain pipes 14 are connected to the filter pipe 10, and the upper plastic hose 1 is connected to the upper plastic hose 12 via a connector. The upper plastic hose 12 is connected to the external vacuum device 17. Figure 10 As shown, a load 19 is piled up on the site. Under the action of the load, the soft soil foundation consolidates and drains. The water collects in the plastic drainage pipe 14 and is discharged from the top of the plastic drainage pipe 14 into the filter pipe 10 and the drainage cushion layer, thus reinforcing the foundation. At this time, the vacuum device 17 is turned on, and the water accumulated in the plastic drainage pipe 14 is drained from the plastic hose 1. The water level of the foundation drops, the effective stress of the soft soil foundation increases, and the reinforcement effect of the soft soil foundation is improved.

[0106] Implementation steps of the present invention:

[0107] The first method for vacuum dewatering preloading using the drainage pipes of Examples 1-3:

[0108] (1) Use drainage board spraying equipment, such as Figure 7 As shown, one end of the plastic drainage pipe 14 is sealed with a plastic cap 20, and then placed on the nozzle of the drainage board hitting device. Using its own weight and vibration force, the nozzle is driven into the soft soil foundation with the plastic drainage pipe 14 by a long rod. The long rod and nozzle are pulled out, and the plastic drainage pipe 14 remains in the soft soil foundation. The plastic drainage pipe 14 protrudes about 5cm above the top surface of the foundation for subsequent operations.

[0109] (2) Figure 8 As shown, all the tube cores are connected to the filter tube 10 using the filter tube tee 9, as follows. Figure 9 As shown, filter tube 10 is connected to vacuum tube 11, filter tube tee 9 is inserted into one end of tube core with a 6mm opening, and plastic hose 1 extends out from the opening;

[0110] (3) Connect the plastic hose 1 extending from the ground to the upper plastic hose 12 using a connector;

[0111] (4) Lay a sealing membrane 13 on the site to be reinforced, and enclose the plastic drainage pipe 14, filter pipe 10, vacuum pipe 11 and plastic hose 1 under the sealing membrane 13. Bury the sealing membrane 13 into the soil at the edge of the site to be reinforced, and fill the soil to form a soil embankment 18. A closed environment is formed under the sealing membrane 13.

[0112] (5) Extend one end of the vacuum tube 11 and the upper plastic hose 12 out of the sealing membrane 13 and connect them to the vacuum equipment 17 respectively, and set valves for each;

[0113] (6) Turn on the vacuum equipment 17 and draw a vacuum. The vacuum tube 11 slowly forms a vacuum. The vacuum degree is controlled between 0.8 and 0.98 atm. The specific value is determined according to the properties of the foundation soil, the reinforcement depth, the reinforcement time and other factors.

[0114] (7) Close the vacuum tube valve 16 intermittently. When the vacuum tube valve 16 is closed, water is discharged from the upper plastic hose 12. When the drainage volume is small, open the vacuum tube valve 16 and repeat the operation. The foundation consolidation and drainage are accelerated by controlling the vacuum level.

[0115] (8) Figure 6 As shown, as the soft soil layer settles, the spiral core 2 begins to enter the outer casing core 4, and the plastic drainage pipe coordinates with the settlement and deformation of the soft soil, thus reinforcing the soft soil foundation.

[0116] The second method is to use the drainage pipes from Examples 1-3 for vacuum dewatering preloading:

[0117] (1) Use drainage board spraying equipment, such as Figure 7 As shown, one end of the plastic drain pipe 14 is first sealed with a plastic cap 20. Then, the plastic drain pipe 14 with the bottom already sealed is placed on the gun head of the drainage board hitting device. Using its own weight and vibration force, the gun head is driven into the soft soil foundation with the plastic drain pipe 14 by a long rod. The long rod and the gun head are pulled out, and the plastic drain pipe 14 remains in the soft soil foundation. The plastic drain pipe 14 protrudes about 5cm above the top surface of the foundation for subsequent operations.

[0118] (2) Figure 10 As shown, all tube cores are connected to filter tube 10 using filter tube tee 9, and filter tube 10 is connected to vacuum tube 11. A 6mm hole is reserved at one end of filter tube tee 9 inserted into the tube core, and a plastic hose extends out from the hole.

[0119] (3) Connect the plastic hose 1 extending from the ground to the upper plastic hose 12 using a connector;

[0120] (4) Connect one end of the upper plastic hose 12 to the vacuum device 17;

[0121] (5) Fill the soft soil foundation on which the plastic drainage pipe 14 is installed with a pile carrier 19;

[0122] (6) When the vacuum device 17 is turned on, the water discharged from the soft soil foundation under the action of the filling slab 19 is discharged through the plastic drainage pipe 14 by the vacuum device 17, which lowers the groundwater level and improves the slab preloading effect.

[0123] (7) As the soft soil layer settles, the spiral core 2 enters the outer core 4, and the plastic drainage pipe coordinates the settlement and deformation of the soft soil, thus reinforcing the soft soil foundation.

[0124] The above description of the embodiments is provided to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention are within the protection scope of the present invention.

Claims

1. A settlement-coordinated drainage pipe for soft soil foundation reinforcement, characterized in that, include: The spiral core (2) and the outer core (4) are provided. The spiral core (2) includes a compressible spring structure composed of a spiral spring body (21) and has the ability to adapt to axial pressure and compress along the axial direction. The spiral core (2) has cylindrical interfaces (24) at both ends. The outer surface of the cylindrical interface (24) is provided with reinforcing ribs (7). The outer core (4) is a cylindrical structure with holes (6) evenly distributed on the tube wall (5). The inner surface of the interfaces at both ends of the outer core (4) is provided with reinforcing ribs (7). The outer surfaces of the spiral core (2) and the outer core (4) are respectively covered with a water-permeable filter membrane. The ribs (7) at both ends of the spiral core (2) and the outer core (4) are evenly distributed in an alternating array along the circumference of the pipe. The rib at one end of the spiral core (2) is aligned with the gap between the ribs at one end of the outer core (4) and inserted. After nesting and insertion, it is rotated to prevent slippage, forming a basic unit of the expandable and adjustable drainage pipe. Two or more of the basic units of the drainage pipe are nested and inserted into each other to form a drainage pipe (14) to adapt to the settlement and deformation of the foundation. The cross-section of the helical spring body (21) is rectangular. The width of the rectangle located on the outer side of the helical core is equal to the width of the helical spring gap (22), which is 1 / 2 of the pitch of the adjacent helical spring bodies (21). The rib (7) is an isosceles trapezoid, and the height of the isosceles trapezoid is 0.075 times the sum of the outer diameter of the spiral core (2) and twice the thickness of the filter membrane, so as to reserve enough space for the radial expansion generated when the spiral core (2) is compressed; The length of the outer sleeve core (4) is 1 / 2 to 2 / 3 times the length of the spiral core (2) to meet the maximum compression deformation of the drainage pipe by 2 / 3 to 3 / 5 times; The nested insertion of the spiral core (2) into the end of the molded silicone rubber wedge ring (23) with the same height as the rib is to increase the friction between the spiral core (2) and the outer core (4), prevent random sliding, and ensure the sealing of the nested connection of the drain pipe; A plastic hose (1) is installed inside the drain pipe, hanging from the top of the drain pipe (14) to the bottom, deforming in conjunction with the drain pipe (14) to form an independent drainage channel.

2. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 1, characterized in that, The spiral core (2) is made of high-strength and high-density polyethylene, and the outer core (4) is made of pressure-resistant high-density polyethylene.

3. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 2, characterized in that, The Poisson's ratio of the high-strength, high-density polyethylene material of the spiral core (2) is 0.

3.

4. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 1, characterized in that, The inner diameter of the outer sleeve core (4) is at least 1.15 times the sum of the outer diameter of the spiral core (2) and twice the thickness of the filter membrane.

5. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 1, characterized in that, The wall thickness of the helical spring body (21) and cylindrical interface (24) is 3-5mm, and the wall thickness of the outer core tube (5) is 1-3mm.

6. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 1, characterized in that, The length of the drainage pipe (14) is 3 to 40 m.

7. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 1, characterized in that, The plastic hose (1) is made of elastic low-density polyethylene with a corrugated inner surface to accommodate settlement deformation and maintain unobstructed drainage.

8. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 1, characterized in that, The permeable filter membrane is a permeable geotextile.

9. The settlement-coordinated drainage pipe for soft soil foundation reinforcement according to claim 8, characterized in that, The permeable geotextile is integrated with the spiral core (2) or the outer core (4) by a hot-melt process.

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