Water-rich soft soil foundation composite reinforcing system and mounting method thereof

Abstract

The invention discloses a water-rich soft soil foundation composite reinforcing system and a mounting method thereof, and belongs to the technical field of geotechnical engineering soft foundation treatment. The system comprises anti-seepage geotechnical cloth laid on a roadbed base, a dense bamboo raft layer laid on the anti-seepage geotechnical cloth and multiple layers of backfill materials arranged on the dense bamboo raft layer in a filling mode. The dense bamboo rafts are formed by weaving bamboo chips subjected to preservative treatment, and the adjacent bamboo rafts are fixedly connected through steel wires. The installation method comprises the steps of roadbed leveling, anti-seepage geotextile laying, dense bamboo raft laying and fixing, backfill layered filling and roadbed detection and acceptance. The seepage-proof geotextile and the dense bamboo rafts form a composite reinforced structure, load can be effectively diffused, soft soil additional stress is reduced, roadbed filler and soft soil are isolated, a certain drainage channel is provided, and meanwhile the structure has the advantages that local materials are used, and the structure is economical, environmentally friendly, easy and convenient to construct, short in construction period and the like; and the method is particularly suitable for shallow roadbed reinforcement projects in coastal water-rich soft soil areas.

Description

Technical Field

[0001] This invention relates to the fields of geotechnical engineering and roadbed treatment technology, and in particular to a composite reinforcement system for water-rich soft soil foundations and its installation method. Background Technology

[0002] In the construction of municipal roads, seawalls, and site works in coastal areas and river deltas, silty soft soils with high water content, large porosity, high compressibility, low bearing capacity, and poor permeability are widely distributed. If this type of water-rich soft soil foundation is not treated before construction, it can easily lead to excessive settlement, uneven settlement, slippage and instability of the roadbed, seriously affecting the safety, quality, and durability of the project.

[0003] Currently, there are many methods for reinforcing soft soil foundations, including cement-soil mixing piles, jet grouting piles, plastic drainage board surcharge preloading, and replacement layer methods. While cement-soil mixing piles and jet grouting piles can effectively improve the bearing capacity of the foundation, they suffer from problems such as high cement consumption, high cost, high construction energy consumption, and potential alkaline pollution of the surrounding soil and groundwater, making them uneconomical and environmentally unfriendly. Plastic drainage board combined with surcharge preloading has a long construction period, requiring a considerable preloading stabilization time, making it difficult to meet the requirements of rapid construction, and its economic benefits are poor for shallow soft soil treatment. Traditional replacement methods, if involving complete replacement of soft soil, result in a large workload, a lot of waste soil, and high costs. For some shallow treatment conditions, bamboo rafts and brambles have been used for reinforcement in the past, but traditional bamboo rafts are loosely laid, have poor integrity, and are prone to decay, resulting in limited reinforcement effects, insufficient long-term stability, and failure to be combined with effective seepage prevention and isolation measures. While geotextiles can serve as a barrier, prevent seepage, and drain when used alone, their tensile strength is limited, making them less effective at resisting uneven settlement and distributed loads.

[0004] Therefore, in view of the above-mentioned defects in the existing technology, especially the problem of difficulty in balancing economy, environmental protection, construction efficiency and long-term stability in the reinforcement of shallow subgrade in coastal water-rich soft soil areas, there is an urgent need to invent a composite reinforcement system and supporting construction method that is relatively simple to construct, has low engineering cost, is environmentally friendly and can provide excellent mechanical properties. Summary of the Invention

[0005] The purpose of this invention is to provide a composite reinforcement system for water-rich soft soil foundations and its installation method, so as to solve the problems of high cost, long construction period, poor environmental performance or insufficient overall stability of existing soft soil reinforcement technologies.

[0006] To achieve the above objectives, the present invention provides a composite reinforcement system for water-rich soft soil foundation, comprising impermeable geotextile, dense bamboo mat, and backfill material laid sequentially from bottom to top;

[0007] The impermeable geotextile is laid on the leveled roadbed base;

[0008] The dense bamboo rafts are laid on impermeable geotextile, and the dense bamboo rafts are spliced ​​and fixed together from multiple independent bamboo raft units.

[0009] The backfill material is filled and compacted in layers on the dense bamboo raft.

[0010] Preferably, the impermeable geotextile is a high-density polyethylene waterproof membrane, and the nominal thickness of the impermeable geotextile is not less than 1 mm, and the permeability coefficient is not greater than 5 × 10⁻⁶. -11 The tensile strength in both the longitudinal and transverse directions is not less than 12 kN / m.

[0011] Preferably, the size of the bamboo raft unit in the dense bamboo raft is 1.0m × 0.6m, and adjacent bamboo raft units are fixed by steel wire binding in both the longitudinal and transverse directions.

[0012] Preferably, the bamboo raft unit is woven from multiple bamboo strips, the bamboo strips are bamboo pieces, the width of the bamboo pieces is 4cm to 6cm, the thickness of the bamboo pieces is not less than 2cm, the longitudinal spacing between adjacent bamboo strips in the same bamboo raft unit is not greater than 1cm, so that the surface gap width of the bamboo raft unit is not greater than 3cm.

[0013] Preferably, the bamboo strips are made of bamboo that has been dried and treated with preservatives.

[0014] Preferably, the backfill material comprises a first slag layer, a large rock layer, and a second slag layer, which are filled in layers from bottom to top.

[0015] Preferably, the compacted thickness of the first slag layer is 20cm, the filling thickness of the large rock layer is 100cm, and the particle size of the large rocks in the large rock layer is not less than 50cm, and the filling thickness of the second slag layer is not less than 80cm.

[0016] This invention provides an installation method for a composite reinforcement system for water-rich soft soil foundations, comprising the following steps:

[0017] S1. Leveling the original roadbed: Leveling the water-rich soft soil foundation area that needs reinforcement treatment to form the roadbed base;

[0018] S2. Lay impermeable geotextile: Fully lay impermeable geotextile on the leveled roadbed base.

[0019] S3. Lay dense bamboo rafts: Lay dense bamboo rafts on the impermeable geotextile and fix adjacent bamboo raft units together with steel wire to form a whole.

[0020] S4. Roadbed backfilling: On top of the laid dense bamboo rafts, backfill material is filled and compacted in layers.

[0021] S5. Subgrade testing: Various indicators of the backfilled and compacted subgrade are tested. Once the subgrade passes the tests, the subsequent pavement structure construction can begin.

[0022] Preferably, in step S3, the laying of the bamboo raft unit requires manual operation, and care should be taken to avoid damaging the underlying impermeable geotextile.

[0023] Preferably, step S4 specifically includes: first, filling and compacting the first slag layer on the dense bamboo raft; then filling the first slag layer with a layer of large stones; and finally filling the second slag layer on the layer of large stones.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] 1. The composite reinforcement system for water-rich soft soil foundations provided by this invention combines high-strength impermeable geotextile with dense bamboo rafts possessing sufficient rigidity and strength, forming a composite structure of "flexible isolation layer + rigid reinforcement layer". This structure can effectively diffuse the upper backfill load, significantly reduce the additional stress on the lower soft soil foundation, and reduce uneven settlement. At the same time, the bamboo rafts themselves have good bending stiffness, which can restrain the lateral deformation of the soft soil and improve the overall stability of the roadbed.

[0026] 2. This invention system combines multiple functions, including reinforcement, isolation, seepage prevention, auxiliary drainage, and stress diffusion. The impermeable geotextile effectively isolates the upper coarse-particle backfill material from the lower soft soil, preventing them from mixing. Simultaneously, its extremely low permeability coefficient blocks capillary upwelling of groundwater, keeping the roadbed dry. The gaps in the dense bamboo rafts serve as horizontal drainage channels, accelerating the drainage and consolidation of the soft soil under load. The combination of these two materials, working synergistically, yields better results than either material alone.

[0027] 3. The main reinforcing material used in this invention, bamboo rafts, can be sourced locally or nearby. Bamboo is a fast-growing and renewable resource, and its production energy consumption is far lower than that of traditional reinforcing materials such as steel and cement. After anti-corrosion treatment, the bamboo rafts can meet the durability requirements of the project. The entire system avoids the extensive use of non-degradable or high-energy-consuming materials such as cement and plastics, conforms to the concept of green construction, and has a significantly lower cost than methods such as cement mixing piles.

[0028] 4. The construction process of this invention is simple, requiring no large or complex equipment. The laying and binding of bamboo rafts and the laying of geotextile can all be done primarily manually, making it highly adaptable to different construction sites. Compared to methods that require long-term curing or preloading, this method significantly shortens the construction cycle, quickly forms a stable roadbed, and helps accelerate the overall project progress.

[0029] 5. The system of this invention is designed for the replacement and reinforcement of roadbeds in coastal areas with shallow (e.g., within 3-5 meters) water-rich soft soil, silt, and dredged fill. It can give full play to its advantages of shallow reinforcement and isolation, and effectively deal with the problem of shallow soft soil at a relatively low cost. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the elevation structure of the composite reinforcement system of the present invention when applied to excavated road sections.

[0032] Figure 2 This is a schematic diagram of the elevation structure of the composite reinforcement system when the present invention is applied to embankment sections.

[0033] Figure 3 This is a flowchart illustrating the installation method of the composite reinforcement system for water-rich soft soil foundations of the present invention.

[0034] In the diagram: 1. Impermeable geotextile; 2. Dense bamboo rafts; 3. First quarry layer; 4. Large stone layer; 5. Second quarry layer; 6. Road surface structure. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] like Figures 1 to 2 As shown, the present invention provides a composite reinforcement system for water-rich soft soil foundation, comprising impermeable geotextile 1, dense bamboo mat 2 and backfill material laid sequentially from bottom to top;

[0037] The impermeable geotextile 1 is laid on the leveled roadbed base;

[0038] The dense bamboo raft 2 is laid on the impermeable geotextile 1. The dense bamboo raft 2 is composed of multiple independent bamboo raft units spliced ​​and fixed together.

[0039] The backfill material is filled in layers and compacted on the dense bamboo raft 2.

[0040] This invention, through the aforementioned technical solution, can construct a multi-layered, multi-functional composite roadbed reinforcement structure. The bottom layer, the impermeable geotextile 1, directly contacts the soft soil foundation, playing a crucial role in isolation and seepage prevention; the middle layer, the dense bamboo mat 2, serves as the core reinforcement layer, providing strong tensile and bending stiffness to distribute the load; and the upper backfill material forms the roadbed body. These three elements work synergistically to address the core problems of insufficient bearing capacity, excessive deformation, and poor stability in water-rich soft soil foundations, making it particularly suitable for shallow treatment.

[0041] The design was further optimized. Geotextile 1 is a high-density polyethylene waterproof membrane with a nominal thickness of not less than 1 mm and a permeability coefficient not greater than 5 × 10⁻⁶. -11 The tensile strength in both the longitudinal and transverse directions is not less than 12 kN / m.

[0042] By using high-density polyethylene waterproof membrane with specific parameters, the geotextile 1 effectively ensures reliable isolation and seepage prevention. Its thickness of at least 1mm and extremely high impermeability effectively prevent groundwater rise and the migration of soil particles between upper and lower layers, creating a relatively dry and stable working environment for the upper subgrade. Simultaneously, its bidirectional tensile strength of at least 12KN / m ensures that the geotextile 1 is not easily torn or damaged during construction and service, thus participating in load-bearing as part of the composite structure.

[0043] Further optimization of the scheme: the size of the bamboo raft unit in the dense bamboo raft 2 is 1.0m×0.6m, and the adjacent bamboo raft units are fixed by steel wire binding in both the longitudinal and transverse directions.

[0044] By designing the bamboo rafts into standard-sized modular units (1.0m × 0.6m) and securing them with steel wire in both longitudinal and transverse directions, the system facilitates transportation, rapid on-site assembly, and ensures the integrity of the reinforcement layer. This standardized modular design improves construction efficiency and quality control. The secure binding with steel wire connects the dispersed bamboo raft units into a continuous and complete reinforcement mesh, allowing them to work collaboratively as a whole. This effectively transfers and disperses stress, preventing a decrease in reinforcement effectiveness due to localized damage or connection failure.

[0045] Further optimization of the design: the bamboo raft unit is woven from multiple bamboo strips, which are bamboo pieces with a width of 4cm to 6cm and a thickness of not less than 2cm. The longitudinal spacing between adjacent bamboo strips within the same bamboo raft unit is not greater than 1cm, so that the surface gap width of the bamboo raft unit is not greater than 3cm.

[0046] By strictly defining the size, spacing, and overall gaps of the bamboo strips, the dense bamboo raft 2 can be designed to ensure sufficient rigidity, strength, and proper drainage. Bamboo strips approximately 5cm wide and at least 2cm thick provide good flexural modulus. A bamboo strip spacing of no more than 1cm ensures sufficient compactness, providing high in-plane stiffness and tensile strength, effectively bearing and distributing loads. Simultaneously, gaps of no more than 3cm ensure a certain degree of permeability, facilitating the drainage of water above and below the raft layer, without being too large to cause significant loss of the fine-grained backfill soil above.

[0047] The design has been further optimized, with the bamboo strips made from dried and preservative-treated bamboo.

[0048] By drying and preservative-treated bamboo, the durability of bamboo rafts can be significantly improved, biological decay can be prevented, and the service life of the project can be extended. Untreated bamboo is prone to mold and insect infestation in water-rich environments, and its strength deteriorates rapidly. Appropriate drying to reduce moisture content and preservative treatment, such as impregnation with environmentally friendly preservatives like borates and copper azole, can greatly improve the durability of bamboo in humid or even alternating wet and dry environments, ensuring the stable performance of the reinforced structure within the design service life of the roadbed.

[0049] The scheme was further optimized, and the backfill material included a first slag layer 3, a large rock layer 4, and a second slag layer 5, which were filled in layers from bottom to top.

[0050] By designing the backfill material into a specific three-layer composite structure, stress transfer can be optimized, drainage consolidation can be strengthened, and a stable subgrade structure can be formed. The first slag layer 3, which is close to the bamboo rafts 2, is relatively thin and mainly serves to level, protect the bamboo rafts, and initially diffuse stress. The middle layer of large stones 4 forms a solid skeleton with high porosity, which can quickly dissipate load stress from the upper part and form a strong vertical drainage channel to accelerate the drainage consolidation of the underlying soft soil. The uppermost second slag layer 5 is the main subgrade bearing layer and leveling layer, providing a flat and solid base for the pavement structure 6.

[0051] Further optimization of the scheme: the compaction thickness of the first slag layer 3 is 20cm, the filling thickness of the large rock layer 4 is 100cm, and the particle size of the large rocks in the large rock layer 4 is not less than 50cm, and the filling thickness of the second slag layer 5 is not less than 80cm.

[0052] By specifying the thickness of each backfill layer and the particle size of key materials, construction parameters can be quantified, ensuring the reproducibility of the reinforcement effect. The 20cm first slag layer 3 is sufficient to protect the bamboo rafts and provide an initial compaction platform. The 100cm thick layer 4 of large stones with a particle size of not less than 50cm forms a stable "stone arch" effect and provides significant drainage and pressure relief. The second slag layer 5, not less than 80cm thick, ensures sufficient subgrade height and compaction thickness to meet the bearing capacity requirements of the pavement structure 6. These parameters are optimized values ​​based on engineering practice, balancing effectiveness, cost, and construction feasibility.

[0053] like Figure 3 As shown, the present invention provides an installation method for a composite reinforcement system for water-rich soft soil foundations, comprising the following steps:

[0054] S1. Leveling the original roadbed: Leveling the water-rich soft soil foundation area that needs reinforcement treatment to form the roadbed base;

[0055] S2. Lay impermeable geotextile 1. Fully lay impermeable geotextile 1 on the leveled roadbed base.

[0056] S3. Lay dense bamboo rafts 2. Lay dense bamboo rafts 2 on impermeable geotextile 1 and fix adjacent bamboo raft units with steel wire to form a whole.

[0057] S4. Roadbed backfilling: On top of the laid dense bamboo rafts 2, backfill material is filled and compacted in layers.

[0058] S5. Subgrade testing: Conduct various tests on the backfilled and compacted subgrade. Once the tests are passed, proceed to the subsequent pavement structure construction.

[0059] The systematic installation steps outlined above guide construction, ensuring the composite reinforcement system is correctly constructed and functions as intended. The process is logically clear, starting with foundation treatment, proceeding to material laying, layered backfilling, and final acceptance, with each step interconnected to guarantee construction quality.

[0060] To further optimize the plan, in step S3, the bamboo raft units need to be laid manually, and care should be taken to avoid damaging the underlying impermeable geotextile 1.

[0061] By emphasizing manual operation during the laying of the dense bamboo rafts and taking care to protect the geotextile, damage to the critical seepage-proof isolation layer can be prevented during construction. Manual laying offers high flexibility, is easy to operate in complex terrain, and allows for better control of laying force and position, avoiding punctures or scratches to the geotextile that may be caused by mechanical construction, thus ensuring the integrity of its seepage-proof function.

[0062] Further optimization of the scheme, step S4 specifically includes: first, filling and compacting the first slag layer 3 on the dense bamboo raft 2; then filling the first slag layer 3 with a large stone layer 4; and finally filling the second slag layer 5 on the large stone layer 4.

[0063] By refining the specific layering sequence and methods for roadbed backfilling, the quality of backfilling construction can be ensured, and the functions of each layer of materials can be fully utilized. Strictly following the sequence of "thin layer of quarry protection → large rock skeleton layer → thick layer of quarry roadbed" effectively protects the substructure and gradually establishes a stable roadbed system. After each layer is filled, necessary leveling and compaction are required. The large rock layer (layer 4) is primarily stabilized through interlocking, ensuring tight interlayer bonding and good overall integrity.

[0064] The composite reinforcement system for water-rich soft soil foundations provided by this invention has the following overall implementation process: First, according to the design elevation and slope requirements, the original ground surface of the coastal water-rich soft soil area is excavated or leveled to form a working surface for the roadbed base that meets the requirements. Next, a geotextile 1 that meets the technical requirements is laid on the treated base. During laying, it should be kept flat and taut; overlapping or welding can be used for connection if necessary. Then, prefabricated dense bamboo raft units 2 are manually laid on the geotextile. During laying, the units are laid out according to the design position, closely spaced, and firmly tied together in both longitudinal and transverse directions with steel wire to form a continuous and complete reinforcement layer. This process requires careful handling to prevent damage to the geotextile. After the bamboo rafts are laid, the first slag layer 3, approximately 20cm thick, is immediately filled on top and compacted with light compaction machinery. This layer protects the bamboo rafts and provides a working surface for subsequent construction. Subsequently, a layer of large stones, approximately 100cm thick, is filled in. Hard stones with a particle size of at least 50cm are selected and placed mechanically or manually to ensure dense compaction and a stable framework. Finally, a second layer of quarry waste (second quarry waste layer 5), at least 80cm thick, is filled on top of the large stone layer, compacted layer by layer to the design required compaction degree. After all backfilling is completed, the elevation, flatness, width, compaction degree, and deflection value of the formed roadbed are tested. Only after passing these tests can subsequent structural construction, such as the pavement subbase, base course, and surface course, proceed.

[0065] This invention, through the ingenious combination of impermeable geotextile 1 and dense bamboo rafts 2, forms an economical, environmentally friendly, efficient, and mechanically superior solution for shallow soft soil foundation reinforcement. This system effectively isolates the roadbed from the soft soil, diffuses loads to reduce settlement, provides drainage paths to accelerate consolidation, and constrains lateral soil deformation, thereby significantly improving roadbed stability and reducing post-construction settlement. Compared to traditional methods such as cement-soil mixing piles and plastic drainage boards, this invention has outstanding advantages such as low material cost, fast construction speed, no need for complex equipment, and minimal environmental disturbance. It is particularly suitable for large-scale application in shallow foundation treatment for roads, embankments, and site leveling projects in water-rich soft soil areas such as coastal areas and riverbanks, yielding significant social and economic benefits.

[0066] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite reinforcement system for water-rich soft soil foundations, characterized in that, It includes impermeable geotextile (1), dense bamboo mat (2) and backfill material laid from bottom to top; The impermeable geotextile (1) is laid on the leveled roadbed base; The dense bamboo raft (2) is laid on the impermeable geotextile (1), and the dense bamboo raft (2) is spliced ​​and fixed by multiple independent bamboo raft units; The backfill material is filled and compacted in layers on the dense bamboo raft (2).

2. The composite reinforcement system for water-rich soft soil foundations according to claim 1, characterized in that, The impermeable geotextile (1) is a high-density polyethylene waterproof membrane. The nominal thickness of the impermeable geotextile (1) is not less than 1 mm, and the permeability coefficient is not greater than 5 × 10⁻⁶. -11 The tensile strength in both the longitudinal and transverse directions is not less than 12 kN / m.

3. The composite reinforcement system for water-rich soft soil foundations according to claim 1, characterized in that, The bamboo raft unit in the dense bamboo raft (2) has a size of 1.0m×0.6m, and adjacent bamboo raft units are fixed by steel wire in both the longitudinal and transverse directions.

4. The composite reinforcement system for water-rich soft soil foundations according to claim 3, characterized in that, The bamboo raft unit is woven from multiple bamboo strips. The bamboo strips are bamboo pieces with a width of 4cm to 6cm and a thickness of not less than 2cm. The longitudinal spacing between adjacent bamboo strips within the same bamboo raft unit is not greater than 1cm, so that the surface gap width of the bamboo raft unit is not greater than 3cm.

5. The composite reinforcement system for water-rich soft soil foundations according to claim 4, characterized in that, The bamboo strips are made from bamboo that has been dried and treated with preservatives.

6. The composite reinforcement system for water-rich soft soil foundations according to claim 1, characterized in that, The backfill material includes a first slag layer (3), a large rock layer (4), and a second slag layer (5) that are filled in layers from bottom to top.

7. The composite reinforcement system for water-rich soft soil foundations according to claim 6, characterized in that, The first slag layer (3) has a compacted thickness of 20cm, the large rock layer (4) has a filling thickness of 100cm, and the large rock in the large rock layer (4) has a particle size of not less than 50cm. The second slag layer (5) has a filling thickness of not less than 80cm.

8. An installation method for a composite reinforcement system for water-rich soft soil foundations as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Leveling the original roadbed: Leveling the water-rich soft soil foundation area that needs reinforcement treatment to form the roadbed base; S2. Lay impermeable geotextile (1). Lay impermeable geotextile (1) on the leveled roadbed base. S3. Lay dense bamboo rafts (2). Lay dense bamboo rafts (2) on the impermeable geotextile (1) and fix adjacent bamboo raft units with steel wire to form a whole. S4. Roadbed backfilling: On top of the laid dense bamboo rafts (2), backfill material is filled and compacted in layers. S5. Subgrade testing: Various indicators of the backfilled and compacted subgrade are tested. After passing the tests, the subsequent pavement structure (6) construction begins.

9. The installation method according to claim 8, characterized in that, In step S3, the bamboo raft unit needs to be laid manually, and care should be taken to avoid damaging the underlying impermeable geotextile (1).

10. The installation method according to claim 8, characterized in that, Step S4 specifically includes: first, filling and compacting the first slag layer (3) on the dense bamboo raft (2); then filling the first slag layer (3) with a large stone layer (4); and finally filling the second slag layer (5) on the large stone layer (4).

Images