Method for supporting and reinforcing foundation pit in soft soil area through straw piles

Abstract

The invention discloses a method for supporting and reinforcing a foundation pit in a soft soil area through straw piles, and belongs to the technical field of pile foundation pit supporting. The method comprises the following steps that S1, straw, cohesive soil and water are pressed layer by layer according to the proportion through a steel formwork, and prefabricated straw piles are manufactured after drying; s2, determining the length of a straw pile according to the excavation depth of the foundation pit; s3, the number of piles and the minimum center distance between the piles are determined before foundation pit support, and the piles are distributed in a multi-row circular dense pile distribution mode; s4, measuring and setting out according to the construction drawing of the retaining structure pile foundation; s5, piles are distributed in a static pile pressing mode; s6, pile distribution construction operation of the straw piles is completed, and follow-up foundation pit excavation operation is carried out. On the basis that the straw piles are used for pile foundation supporting of the foundation pit in the soft soil area, the overall shear strength of the soil body is improved through a composite structure formed by straw and the soil body, horizontal supporting can be reduced, and the construction efficiency is improved; the straw piles can play a certain role in drainage and consolidation in the enclosure process, and have the advantages of soil improvement, economy and environmental protection in the enclosure process.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation pit enclosure, and in particular to a method for enclosing and reinforcing a foundation pit in a soft soil area by utilizing straw piles. Background Art

[0002] Foundation pit support is an indispensable part of civil engineering, which is related to the safety and stability of the project. Although traditional foundation pit support materials such as steel sheet piles and concrete piles have excellent performance, they are expensive and may be difficult to construct in certain specific environments (such as coastal areas, basement excavation, etc.).

[0003] Existing methods for retaining foundation pits mainly include slope excavation and simple support, soil nail wall support structure, and internal support retaining structure. Slope excavation is to select a reasonable slope for excavation. Slope excavation is simple to construct and low in cost, but the amount of excavation and backfilling is large, and it is easy to collapse locally due to soaking in the rainy season. The soil nail wall support structure is composed of reinforced in-situ soil, densely arranged soil nails, and concrete panels sprayed on the slope. The soil nail wall support is stable, reliable, and economical, but it is not suitable for use in areas with poor soil quality. It requires earthwork to cooperate with layered excavation, and more equipment is required for construction sites with tight construction period requirements. The internal support retaining structure is composed of support piles or walls and internal supports. The wall body has high strength, high rigidity, good support stability, and small deformation, but the cost is high, the construction period is long, and the gaps between the piles are prone to 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 object of the present invention is to provide a method for surrounding and reinforcing foundation pits in soft soil areas using straw piles, so as to solve the problems raised in the above-mentioned background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for enclosing and reinforcing foundation pits in soft soil areas using straw piles, comprising the following steps:

[0006] S1. Press straw, clay and water in proportion using steel templates, and make prefabricated straw piles after drying;

[0007] S2. Determine the length of the straw pile according to the excavation depth of the foundation pit;

[0008] S3. Determine the number of piles and the minimum center distance between piles before retaining the foundation pit, and use a multi-row circular dense arrangement of piles. Select different types of piles according to needs to ensure that the density of the retaining structure pile foundation meets the requirements;

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

[0010] S5. Start laying piles by static pile pressure;

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

[0012] In a further embodiment, the straw pile includes several sections of pile body and pile head, and upper and lower connecting parts of the pile body are provided between adjacent pile bodies. Vertical bamboo strips are provided around the upper and lower connecting parts of the pile body. Binding ropes are provided at the upper and lower parts of the upper and lower connecting parts of the pile body. An upper embedding groove is opened on the pile head, and the bottom of the pile body in the lowest section cooperates with the upper embedding groove.

[0013] In a further embodiment, in the step S1, during the production process of the straw pile, the layered parts need to be roughened, the diameter of the straw pile head is slightly larger than the diameter of the straw pile body, and a compression-resistant annular sheath 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 circles of straw piles is 2-3 times of the pile diameter, and the pile diameter is the pile diameter of a large-sized straw pile.

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

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

[0018] In a further embodiment, in step S6, on the basis of using the straw piles to surround the foundation pit in the soft soil area, the soil around the supporting piles is reinforced with the straw piles.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses straw piles to support the foundation pit in soft soil areas, and reinforces the soil around the supporting piles. The composite structure formed by the straw and the soil improves the overall shear strength of the soil, and can reduce horizontal support. The straw piles can play a certain role in drainage and consolidation during the enclosure process; the straw piles are used to support the foundation pit in soft soil areas, and do not need to be pulled out in the later stage. In addition, agricultural waste straw is used to make piles, which has a low cost and has great advantages in terms of economy. In the enclosure process, it has the advantages of improving soil quality and being economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 2It is a schematic diagram of the arrangement of the foundation pit enclosure in soft soil area using straw piles of the present invention;

[0022] Figure 3 It is a schematic diagram of the arrangement of using straw piles to surround soft soil areas with support piles and to reinforce the soil around the support piles;

[0023] The accompanying drawings are marked as: pile body 1, upper and lower connecting parts of the pile body 2, vertical bamboo strips 3, upper embedded grooves 4, pile heads 5, standard piles 61, matching piles 62, foundation pit excavation boundary 63, first straw pile group 64, second straw pile group 65, third straw pile group 66, nth straw pile group 67, and supporting pile group 68. DETAILED DESCRIPTION

[0024] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0025] See also Figure 1-Figure 3 The present invention provides a technical solution: a method for enclosing and reinforcing a foundation pit in a soft soil area using straw piles, comprising the following steps:

[0026] S1. Press straw, clay and water in proportion using steel templates, and make prefabricated straw piles after drying;

[0027] S2. Determine the length of the straw pile according to the excavation depth of the foundation pit;

[0028] S3. Determine the number of piles and the minimum center distance between piles before retaining the foundation pit, and use a multi-row circular dense arrangement of piles. Select different types of piles according to needs to ensure that the density of the retaining structure pile foundation meets the requirements;

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

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

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

[0032] Through the above technical scheme, straw piles are used to surround small foundation pits in soft soil areas. The straw has a water-absorbing effect and plays a certain drainage and consolidation effect. The enclosure structure makes full use of agricultural waste - straw, which helps to reduce pollution. Clay soil is easy to obtain, which improves the utilization rate of resources. The material cost is relatively low, the operation is simple, the material is easy to obtain, and it has a high economic effect. The pile body material of the straw pile will not produce any pollution in the soil. After the foundation project is completed, the straw pile does not need to be pulled out, avoiding secondary disturbance to the surrounding environment. The straw pile has a certain effect of improving the soil quality after decay, which can improve the looseness, permeability, air permeability and soil fertility of the soft soil. When the loess content is high, it is conducive to the mixing of clay and soft soil, improving the bearing capacity of the soft soil, and at the same time, the decay rate of straw soil can be accelerated by artificially adding microorganisms; the piles are arranged in a circular and dense manner to form an arch effect, which converts the bending and tension internal forces of the structure into annular axial forces, so that the support structure has good ability to resist deformation, the lateral deformation of the circular enclosure structure is small, and the size of the support structure can be reduced. Under the premise of ensuring the safety and reliability of the support structure system, the support cost is saved and the structural stability is improved. At the same time, the multi-row piles have a higher bearing capacity, less erosion to the surrounding soil, good stability, and a stable support frame with strong supporting capacity.

[0033] like Figure 2 As shown, in the case of using straw piles to surround the foundation pit in the soft soil area, a foundation pit excavation boundary line 63 is set at the edge of the foundation pit, and a first straw pile group 64 is set outside the foundation pit excavation boundary line 63, wherein the first straw pile group 64 is composed of a plurality of 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, 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, wherein the second straw pile group 65, the third straw pile group 66 and the nth straw pile group 67 set as needed are composed of a plurality of standard piles 61 arranged in a circular and dense manner, and matching piles 62 are set at intervals between adjacent standard piles 61, and the diameter of the standard piles 61 is larger than the diameter of the matching piles 62, so as to ensure that the density of the pile foundation of the enclosure structure meets the requirements;

[0034] like Figure 3As shown, when straw piles are used to surround the soft soil area with supporting piles and the soil around the supporting piles is reinforced, a foundation pit excavation boundary line 63 is set at the edge of the foundation pit, a supporting pile group 68 is set outside the foundation pit excavation boundary line 63, and a first straw pile group 64 is set outside the supporting pile group 68, wherein the first straw pile group 64 is composed of a plurality of standard piles 61 arranged densely in a circular shape, 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 arranged outside the pile group 66 as required, wherein the second straw pile group 65, the third straw pile group 66 and the nth straw pile group 67 arranged as required are composed of a plurality of standard piles 61 arranged densely in a circle, and auxiliary piles 62 are arranged at intervals between adjacent standard piles 61, and the diameter of the standard piles 61 is larger than the diameter of the auxiliary piles 62, so as to ensure that the density of the pile foundation of the enclosure structure meets the requirements, wherein the method of using straw piles to surround the soft soil area with supporting piles and reinforce the soil around the supporting piles includes the following steps:

[0035] S1. Press straw, clay and water in proportion using steel templates, and make prefabricated straw piles after drying;

[0036] S2. Determine the length of the straw pile according to the excavation depth of the foundation pit;

[0037] S3. Determine the number of piles and the minimum center distance between piles before retaining the foundation pit, and use a multi-row circular dense arrangement of piles. Select different types of piles according to needs to ensure that the density of the retaining structure pile foundation meets the requirements;

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

[0039] S5. Start laying piles by static pile pressure;

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

[0041] In a further embodiment, the straw pile includes several sections of pile body 1 and pile head 5, and an upper and lower connecting part 2 of the pile body is provided between adjacent pile bodies 1. Vertical bamboo strips 3 are provided around the upper and lower connecting parts 2 of the pile body. Binding ropes are provided at the upper and lower parts of the upper and lower connecting parts 2 of the pile body. An upper embedding groove 4 is opened on the pile head 5, and the bottom of the lowest section of the pile body 1 cooperates with the upper embedding groove 4.

[0042] Through the above technical solution, the bonding force and stability of the material are increased by setting the vertical bamboo strips 3, the setting of the binding rope ensures the stability of the upper and lower connecting parts 2 of the body, and the setting of the upper groove 4 facilitates fixing the lowest section of the pile body 1 to the upper end of the pile head 5.

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

[0044] Through the above technical scheme, the resistance of the straw pile body to enter the soil is reduced by using the straw pile head with a slightly larger diameter, and the arrangement of the compression-resistant annular sheath 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] Through the above technical solution, straw piles of appropriate length are set according to the depth of the foundation pit, so that the straw piles can stabilize the foundation pit.

[0047] In a further embodiment, in step S3, the spacing between two adjacent circles of straw piles is 2-3 times the pile diameter, and the pile diameter is the pile diameter of a large-sized straw pile.

[0048] Through the above technical solution, by setting a suitable distance between two adjacent circles of straw piles, it is ensured that the density of the pile foundation of the retaining structure meets the requirements while ensuring the stability of the foundation pit retaining.

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

[0050] Through the above technical solution, the stability of the foundation pit enclosure is ensured by setting appropriate spacing.

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

[0052] The above technical solution ensures the stability of straw pile driving.

[0053] In a further embodiment, in step S6, on the basis of using straw piles to surround the foundation pit in the soft soil area, the soil around the supporting piles is reinforced with straw piles.

[0054] Through the above technical solution, the integrity and stability of the soil are improved by straw piles, the bearing capacity and deformation resistance of the surrounding soil are enhanced, and the horizontal support of the foundation pit can be effectively reduced.

[0055] The preferred specific embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above specific embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical scheme of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A method for protecting and reinforcing foundation pits in soft soil areas using straw piles, characterized in that: The steps include: S1. Press straw, clay and water in proportion using steel templates, and make prefabricated straw piles after drying; S2. Determine the length of the straw pile according to the excavation depth of the foundation pit; S3. Determine the number of piles and the minimum center distance between piles before retaining the foundation pit, and use a multi-row circular dense arrangement of piles. Select different types of piles according to needs to ensure that the density of the retaining structure pile foundation meets the requirements; S4. Measure and set out according to the construction drawing of the pile foundation of the retaining structure; S5. Start laying piles by static pile pressure; S6. Complete the straw pile layout and proceed with subsequent foundation pit excavation.

2. The method for protecting and reinforcing foundation pits in soft soil areas using straw piles according to claim 1, characterized in that: The straw pile comprises a plurality of pile bodies (1) and a pile head (5), wherein an upper and lower connecting portion (2) of the pile body is provided between adjacent pile bodies (1), a vertical bamboo strip (3) is provided around the upper and lower connecting portions (2) of the pile body, and binding ropes are provided at the upper and lower portions of the upper and lower connecting portions (2) of the pile body, an upper embedding groove (4) is provided on the pile head (5), and the bottom of the lowest section of the pile body (1) matches the upper embedding groove (4).

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

4. The method for protecting and reinforcing foundation pits in soft soil areas using straw piles 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. The method for protecting and reinforcing foundation pits in soft soil areas using straw piles according to claim 1, characterized in that: In the step S3, the distance between two adjacent circles of straw piles is 2-3 times of the pile diameter, and the pile diameter is the pile diameter of a large-sized straw pile.

6. The method for protecting and reinforcing foundation pits in soft soil areas using straw piles according to claim 1, characterized in that: In step S3, the straw piles densely arranged in a circle adjacent to the foundation pit are spaced 200-300 mm apart from each other.

7. The method for protecting and reinforcing foundation pits in soft soil areas using straw piles according to claim 1, characterized in that: In step S5, the pile driving speed is strictly controlled during pile driving to avoid soil squeezing effect and soil effect.

8. The method for protecting and reinforcing foundation pits in soft soil areas using straw piles according to claim 1, characterized in that: In the step S6, on the basis of using the straw piles to surround the foundation pit in the soft soil area, the soil around the supporting piles is reinforced with the straw piles.

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