A method for enclosing and reinforcing foundation pits in soft soil areas using straw piles

Abstract

This invention discloses a method for retaining and reinforcing foundation pits in soft soil areas using straw piles, belonging to the field of pile foundation pit retaining technology. The method includes the following steps: S1. Pressing straw, cohesive soil, and water in layers using steel templates according to a specific ratio, and then drying to produce precast straw piles; S2. Determining the length of the straw piles based on the excavation depth of the foundation pit; S3. Determining the number of piles and the minimum center-to-center spacing between piles before retaining the foundation pit, and using a multi-row, densely arranged circular pile layout; S4. Measuring and setting out according to the pile foundation construction drawings of the retaining structure; S5. Starting the pile layout using static pile driving; S6. Completing the straw pile layout and proceeding with subsequent foundation pit excavation. This invention utilizes straw piles for foundation pit support in soft soil areas. The composite structure formed by straw and soil improves the overall shear strength of the soil, reduces horizontal support, and the straw piles can play a certain role in drainage and consolidation during the retaining process. It offers advantages in soil improvement and economic and environmental protection during the retaining process.

Description

Technical Field

[0001] This invention relates to the field of pile foundation pit protection technology, specifically a method for protecting and reinforcing pits in soft soil areas using straw piles. Background Technology

[0002] Foundation pit support is an indispensable part of civil engineering, as it relates to the safety and stability of the project. Traditional foundation pit support materials, such as steel sheet piles and concrete piles, while having excellent performance, are expensive and may present construction difficulties in certain specific environments (such as coastal areas or basement excavation).

[0003] Existing methods for foundation pit support mainly include slope excavation and simple support, soil nailing wall support structures, and internal bracing retaining structures. Slope excavation involves selecting a reasonable slope for excavation. Slope excavation is simple to construct and inexpensive, but it requires a large amount of excavated and backfilled soil, and is prone to local collapse due to soaking during the rainy season. Soil nailing wall support structures consist of reinforced in-situ soil, densely arranged soil nails, and a concrete panel sprayed onto the slope. Soil nailing wall support is stable, reliable, and economical, but it is not suitable for areas with poor soil quality. It requires layered excavation with earthwork coordination, and requires more equipment for sites with tight schedules. Internal bracing retaining structures consist of support piles or walls and internal supports. The walls have high strength and rigidity, good support stability, and small deformation, but the cost is high, the construction period is long, and the gaps between piles can easily cause soil erosion. Therefore, it is necessary to design a method for retaining and reinforcing foundation pits in soft soil areas using straw piles. Summary of the Invention

[0004] The purpose of this invention is to provide a method for protecting and reinforcing foundation pits in soft soil areas using straw piles, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for using straw piles to protect and reinforce foundation pits in soft soil areas, comprising the following steps:

[0006] S1. Press straw, clay and water in layers using steel templates in proportion, and then dry them to make precast straw piles;

[0007] S2. Determine the length of the straw piles based on the excavation depth of the foundation pit;

[0008] S3. Before the foundation pit is protected, determine the number of piles and the minimum center-to-center spacing between piles. Select a pile layout method with multiple rows of densely arranged circular piles. Select different types of piles according to the requirements to ensure that the density of the pile foundation of the retaining structure meets the requirements.

[0009] S4. Measure and set out the pile foundation according to the construction drawings of the retaining structure;

[0010] S5. Begin pile laying using static pile driving;

[0011] S6. Complete the straw pile laying operation and proceed with the subsequent foundation pit excavation operation.

[0012] In a further embodiment, the straw stake includes several stake sections and stake heads. There is an upper and lower connecting part between adjacent stake sections. Vertical bamboo strips are arranged around the upper and lower connecting parts. Binding ropes are provided at the upper and lower parts of the upper and lower connecting parts. An upper groove is opened on the stake head. The bottom of the lowest stake section matches the upper groove.

[0013] In a further embodiment, in step S1, during the production of the straw pile, the layered areas need to be roughened, the diameter of the straw pile head is slightly larger than the diameter of the straw pile body, and a pressure-resistant annular protective sleeve is provided on the top of the straw pile.

[0014] In a further embodiment, in step S2, the length of the straw pile is 2-3 times the depth of the foundation pit.

[0015] In a further embodiment, in step S3, the spacing between two adjacent rings of straw piles is 2-3 times the pile diameter, where the pile diameter is the diameter of a large-sized straw pile.

[0016] In a further embodiment, in step S3, the densely arranged circular straw piles adjacent to the foundation pit are spaced 200-300 mm apart.

[0017] In a further embodiment, in step S5, the piling rate is strictly controlled during piling to avoid soil squeezing and soil effects.

[0018] In a further embodiment, in step S6, based on the straw pile foundation protection of the foundation pit in the soft soil area, the soil around the support piles is reinforced with the straw piles.

[0019] Compared with the prior art, the beneficial effects achieved by this invention are as follows: This invention utilizes straw piles to reinforce the soil around the foundation pits in soft soil areas, based on the pile foundation support. The composite structure formed by the straw and soil improves the overall shear strength of the soil, which can reduce the need for horizontal supports. The straw piles can also play a certain role in drainage and consolidation during the enclosure process. The straw piles used for foundation pit enclosure in soft soil areas do not need to be pulled out later, and the use of agricultural waste straw for piles results in low cost and significant economic advantages. The enclosure process also has the advantages of improving soil quality and being economical and environmentally friendly. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the straw pile structure of the present invention;

[0021] Figure 2 This is a schematic diagram illustrating the use of straw piles for foundation pit protection in soft soil areas according to the present invention;

[0022] Figure 3 This is a schematic diagram illustrating the use of straw piles to reinforce soft soil areas with retaining piles and strengthening the soil around the retaining piles, according to the present invention.

[0023] The attached diagram is labeled as follows: 1. Pile body; 2. Pile body upper and lower connection; 3. Vertical bamboo strip; 4. Upper groove; 5. Pile head; 61. Standard pile; 62. Support pile; 63. Excavation edge line of foundation pit; 64. First straw pile group; 65. Second straw pile group; 66. Third straw pile group; 67. nth straw pile group; 68. Support pile group. Detailed Implementation

[0024] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0025] Please see Figures 1-3 This invention provides a technical solution: a method for using straw piles to protect and reinforce foundation pits in soft soil areas, comprising the following steps:

[0026] S1. Press straw, clay and water in layers using steel templates in proportion, and then dry them to make precast straw piles;

[0027] S2. Determine the length of the straw piles based on the excavation depth of the foundation pit;

[0028] S3. Before the foundation pit is protected, determine the number of piles and the minimum center-to-center spacing between piles. Select a pile layout method with multiple rows of densely arranged circular piles. Select different types of piles according to the requirements to ensure that the density of the pile foundation of the retaining structure meets the requirements.

[0029] S4. Measure and set out the foundation according to the construction drawings of the retaining structure pile foundation to ensure the accuracy and quality of construction and guarantee the safety of the foundation pit support structure and the surrounding environment;

[0030] S5. Static pile driving is used to start the pile layout, which avoids the vibration and noise generated by pile driving and does not damage the piles during construction;

[0031] S6. Complete the straw pile laying operation and proceed with the subsequent foundation pit excavation operation.

[0032] The above technical solution utilizes straw piles for the enclosure of small foundation pits in soft soil areas. Straw has water-absorbing properties, providing drainage and consolidation. The enclosure structure fully utilizes agricultural waste—straw—helping to reduce pollution. Clay soil is readily available, improving resource utilization. Material costs are relatively low, operation is simple, and materials are readily available, resulting in high economic benefits. The straw pile material does not cause any pollution in the soil, and the straw piles do not need to be removed after the foundation work is completed, avoiding secondary disturbance to the surrounding environment. After decomposition, the straw piles also improve soil quality, enhancing the looseness, permeability, aeration, and fertility of soft soil. When the loess content is high, it is beneficial for mixing cohesive soil and soft soil, which improves the bearing capacity of soft soil. At the same time, the decomposition speed of straw soil can be accelerated by adding microorganisms. By arranging piles in a circular and dense manner, an arch effect is formed, which transforms the bending and tensile internal forces on the structure into circumferential axial forces, making the support structure more resistant to deformation. The circular retaining structure has small lateral deformation, which can reduce the size of the support structure. While ensuring the safety and reliability of the support structure system, it saves support costs and improves structural stability. At the same time, the multi-row piles have high bearing capacity, low erosion of the surrounding soil, good stability, and the multi-row pile structure provides a stable support frame with strong support capacity.

[0033] like Figure 2 As shown, when using straw piles to retain foundation pits in soft soil areas, an excavation boundary line 63 is set at the edge of the foundation pit. A first straw pile group 64 is set outside the excavation boundary line 63, which consists of several standard piles 61 arranged in a circular and dense manner. A second straw pile group 65 is set outside the first straw pile group 64, and a third straw pile group 66 is set outside the second straw pile group 65. An nth straw pile group 67 is set outside the third straw pile group 66 as needed. The second straw pile group 65, the third straw pile group 66, and the nth straw pile group 67 as needed are all composed of several standard piles 61 arranged in a circular and dense manner. There are auxiliary piles 62 at the intervals between adjacent standard piles 61. The diameter of the standard pile 61 is larger than the diameter of the auxiliary pile 62 to ensure that the density of the pile foundation of the retaining structure meets the requirements.

[0034] like Figure 3As shown, in the case of using straw piles to reinforce soft soil areas with retaining piles and strengthening the soil around the retaining piles, an excavation boundary line 63 is set at the edge of the excavation pit. A retaining pile group 68 is set outside the excavation boundary line 63. A first straw pile group 64 is set outside the retaining pile group 68, consisting of several densely arranged circular standard piles 61. A second straw pile group 65 is set outside the first straw pile group 64, and a third straw pile group 66 is set outside the second straw pile group 65. The outer side of pile group 66 is provided with the nth straw pile group 67 as needed. The second straw pile group 65, the third straw pile group 66, and the nth straw pile group 67 as needed are composed of several standard piles 61 arranged in a circular and dense manner. Adjacent standard piles 61 are spaced apart by auxiliary piles 62. The diameter of the standard piles 61 is larger than the diameter of the auxiliary piles 62, ensuring that the density of the retaining structure pile foundation meets the requirements. The method of using straw piles to retain soft soil areas and reinforce the soil around the retaining piles includes the following steps:

[0035] S1. Press straw, clay and water in layers using steel templates in proportion, and then dry them to make precast straw piles;

[0036] S2. Determine the length of the straw piles based on the excavation depth of the foundation pit;

[0037] S3. Before the foundation pit is protected, determine the number of piles and the minimum center-to-center spacing between piles. Select a pile layout method with multiple rows of densely arranged circular piles. Select different types of piles according to the requirements to ensure that the density of the pile foundation of the retaining structure meets the requirements.

[0038] S4. Measure and set out the pile foundation according to the construction drawings of the retaining structure;

[0039] S5. Begin pile laying using static pile driving;

[0040] S6. Complete the installation of straw piles and support piles, and proceed with the subsequent excavation of the foundation pit.

[0041] In a further embodiment, the straw stake includes several stake body 1 and stake head 5. There is a stake body upper and lower connecting part 2 between adjacent stake body 1. Vertical bamboo strips 3 are provided around the stake body upper and lower connecting part 2. Binding ropes are provided at the upper and lower parts of the stake body upper and lower connecting part 2. An upper groove 4 is opened on the stake head 5. The bottom of the lowest stake body 1 matches the upper groove 4.

[0042] Through the above technical solution, the vertical bamboo strips 3 are used to increase the adhesion and stability of the material, the binding rope is used to ensure the stability of the upper and lower connecting parts 2, and the upper groove 4 is used to facilitate the fixing of the lowermost pile body 1 to the upper end of the pile head 5.

[0043] In a further embodiment, in step S1, during the production of straw piles, the layers need to be roughened, the diameter of the straw pile head is slightly larger than the diameter of the straw pile body, and a pressure-resistant annular protective sleeve is provided on the top of the straw pile.

[0044] The above technical solution reduces the resistance of the straw pile body to soil by using a straw pile head with a slightly larger diameter, and the setting of the pressure-resistant ring sleeve makes the straw pile body bear the force evenly.

[0045] In a further embodiment, in step S2, the length of the straw pile is 2-3 times the depth of the foundation pit.

[0046] The above technical solution involves setting straw piles of appropriate length according to the depth of the foundation pit, which ensures the stability of the foundation pit enclosure.

[0047] In a further embodiment, in step S3, the spacing between two adjacent rings of straw stakes is 2-3 times the stake diameter, and the stake diameter is the same as that of a large-sized straw stake.

[0048] By using the above technical solution, and by setting an appropriate spacing between two adjacent rings of straw piles, the density of the pile foundation arrangement of the retaining structure is ensured to meet the requirements while guaranteeing the stability of the foundation pit retaining.

[0049] In a further embodiment, in step S3, the densely arranged circular straw piles adjacent to the foundation pit are spaced 200-300 mm apart.

[0050] The above technical solution ensures the stability of the foundation pit retaining structure by setting appropriate spacing.

[0051] In a further embodiment, in step S5, the piling rate is strictly controlled during piling to avoid soil squeezing and soil effects.

[0052] The above technical solutions ensure the stability of straw pile driving.

[0053] In a further embodiment, in step S6, based on the use of straw pile foundation for the foundation pit in the soft soil area, the soil around the support piles is reinforced with straw piles.

[0054] The above technical solution improves the integrity and stability of the soil by using straw piles, enhances the bearing capacity and deformation resistance of the surrounding soil, and can effectively reduce the horizontal support of the foundation pit.

[0055] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A method for using straw piles to protect and reinforce foundation pits in soft soil areas, characterized in that, Includes the following steps: S1. Press straw, clay and water in layers using steel templates in proportion, and then dry them to make precast straw piles; S2. Determine the length of the straw piles based on the excavation depth of the foundation pit; S3. Before the foundation pit is protected, determine the number of piles and the minimum center-to-center spacing between piles. Select a pile layout method with multiple rows of densely arranged circular piles. Select different types of piles according to the requirements to ensure that the density of the pile foundation of the retaining structure meets the requirements. S4. Measure and set out the pile foundation according to the construction drawings of the retaining structure; S5. Begin pile laying using static pile driving; S6. Complete the straw pile laying operation and proceed with the subsequent foundation pit excavation operation; In step S6, when using straw piles to protect the foundation pit in the soft soil area, a foundation pit excavation boundary line (63) is set at the edge of the foundation pit, a first straw pile group (64) is set outside the foundation pit excavation boundary line (63), a second straw pile group (65) is set outside the first straw pile group (64), a third straw pile group (66) is set outside the second straw pile group (65), and an nth straw pile group (67) is set outside the third straw pile group (66) as needed. The first straw pile group (64) consists of several standard piles (61) arranged in a circular and dense manner. The second straw pile group (65), the third straw pile group (66), and the nth straw pile group (67) set as needed are all composed of several standard piles (61) arranged in a circular and dense manner, and there are auxiliary piles (62) at the intervals between adjacent standard piles (61).

2. The method for using straw piles to protect and reinforce foundation pits in soft soil areas according to claim 1, characterized in that: The straw stake includes several stake body (1) and stake head (5). There is a stake body upper and lower connecting part (2) between adjacent stake body (1). Vertical bamboo strips (3) are provided around the stake body upper and lower connecting part (2). There are binding ropes at the upper and lower parts of the stake body upper and lower connecting part (2). An upper groove (4) is opened on the stake head (5). The bottom of the lowest stake body (1) matches the upper groove (4).

3. The method for using straw piles to protect and reinforce foundation pits in soft soil areas according to claim 1, characterized in that: In step S1, during the production of the straw pile, the layered areas need to be roughened, the diameter of the straw pile head is slightly larger than the diameter of the straw pile body, and a pressure-resistant annular protective sleeve is provided on the top of the straw pile.

4. The method for using straw piles to protect and reinforce foundation pits in soft soil areas according to claim 1, characterized in that: In step S2, the length of the straw pile is 2-3 times the depth of the foundation pit.

5. A method for retaining and reinforcing foundation pits in soft soil areas using straw piles as described in claim 1, characterized in that: In step S3, the spacing between two adjacent rings of straw stakes is 2-3 times the stake diameter, where the stake diameter is the diameter of the larger straw stake.

6. A method for retaining and reinforcing foundation pits in soft soil areas using straw piles as described in claim 1, characterized in that: In step S3, the straw piles arranged in a dense circular pattern near the foundation pit are spaced 200-300 mm apart.

7. A method for retaining and reinforcing foundation pits in soft soil areas using straw piles as described in claim 1, characterized in that: In step S5, the piling rate is strictly controlled during piling to avoid soil squeezing and soil effects.

8. A method for retaining and reinforcing foundation pits in soft soil areas using straw piles according to claim 1, characterized in that: In step S6, based on the straw pile foundation protection of the foundation pit in the soft soil area, the soil around the support piles is reinforced with the straw piles.

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