Method and device for reinforcing shallow layer of soil body around pile
By scientifically calculating the reinforcement width and depth of the soil around the pile, and adding polypropylene fiber and cement to the excavated soil to form polypropylene fiber cement soil, the problem of insufficient pile foundation bearing capacity in the existing technology is solved and a more efficient pile foundation reinforcement effect is achieved.
Patent Information
- Application Number
- CN202411626871.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-04-01
AI Technical Summary
The existing cement soil mixing pile reinforcement method lacks scientific basis when selecting the excavation volume of shallow soil around the pile, resulting in the bearing capacity of the reinforced pile foundation still not meeting the actual needs.
By determining the reinforcement width D and reinforcement depth H of the soil around the pile, the excavation volume of the shallow soil is calculated, and an appropriate amount of polypropylene fiber and cement is added to the excavated soil, stirred into polypropylene fiber cement soil, and backfilled to the pile for reinforcement.
It effectively improves the bearing capacity of pile foundations, solves the problem of insufficient bearing capacity of pile foundations in soft soil areas of transmission line, and improves construction safety and economic benefits.
Smart Images
Figure CN119736895A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a shallow reinforcement method and device for soil around piles, belonging to the technical field of shallow foundation reinforcement around pile foundations of power transmission lines in soft soil areas. Background Art
[0002] When the transmission line pile foundation passes through the soft soil area, due to the adverse characteristics of the soft soil such as low stability and low shear strength, it is necessary to carry out shallow reinforcement treatment on the soil around the pile to improve the bearing capacity of the pile foundation.
[0003] Increasing the pile diameter is a relatively effective method to improve the bearing capacity of the pile foundation, but the change in the diameter of the pile foundation often requires a higher cost and a larger floor space, which is not a very good choice. Therefore, in order to improve the horizontal bearing capacity of the pile foundation, shallow reinforcement of the soil is often required. The cement-soil mixing pile reinforcement method is a commonly used shallow foundation reinforcement method around the pile foundation. It uses cement as a curing agent and uses a special mixing machine to force the soil and cement powder to mix within the design range. Through a series of physical and chemical reactions between cement and soil, the soft soil is hardened into cement-reinforced soil with integrity, water stability and a certain strength, and forms a composite foundation with the original soft soil, improving the physical and chemical properties of the natural soil layer, thereby improving the foundation strength and increasing the deformation modulus.
[0004] However, the existing cement-soil mixing pile reinforcement method generally selects the excavation volume of the shallow soil around the pile based on experience, so that the bearing capacity of the reinforced pile foundation still does not meet actual needs. Summary of the invention
[0005] In order to solve the problems existing in the prior art, the present invention provides a shallow reinforcement method and device for soil around a pile for improving the bearing capacity of a single pile.
[0006] In order to achieve the above object, the technical solution proposed by the present invention is: a shallow reinforcement method of soil around piles, comprising the following steps:
[0007] Step 1: Determine the reinforcement width D and depth H of the soil around the pile, and then obtain the shallow soil excavation volume:
[0008]
[0009] b=0.57D cem +1
[0010]
[0011] Where: F1 is the design value of pile bearing capacity; F0 is the actual bearing capacity of the pile; a is the depth improvement factor; b is the width improvement factor; D cem H is the ratio of the reinforcement width D to the pile diameter d, cemis the ratio of the reinforcement depth H to the pile diameter d; d is the pile diameter; V is the excavation volume of the shallow soil around the pile;
[0012] Step 2: excavate shallow soil around the pile according to the reinforcement width D and reinforcement depth H obtained in step 1;
[0013] The soil excavation and loading device (1) is used to excavate the shallow soil around the pile, and the soil is transported to the polypropylene fiber cement soil container (3) through the soil transport device (2).
[0014] Step 3: Mix a certain amount of polypropylene fiber and cement into the excavated soil, and then add water and stir to prepare polypropylene fiber cement soil;
[0015] Step 4: Backfill the prepared polypropylene fiber cement soil around the pile and compact it to reinforce the shallow layer of the soil around the pile.
[0016] A further design of the above technical solution is as follows: in step three, the cement content is 5%-25% of the weight of the excavated soil, and the polypropylene fiber content is 0.2%-0.6% of the weight of the excavated soil.
[0017] A preferred embodiment of the above technical solution is that the cement content is 20% of the weight of the excavated soil, and the polypropylene fiber content is 0.2% of the weight of the excavated soil.
[0018] A preferred embodiment of the above technical solution is that the cement content is 5%-15% of the weight of the excavated soil, and the polypropylene fiber content is 0.4% of the weight of the excavated soil.
[0019] A preferred embodiment of the above technical solution is that the fiber length of the polypropylene fiber is 6mm-15mm.
[0020] A preferred embodiment of the above technical solution is that when the polypropylene fiber content is 0.2%-0.4% of the weight of the excavated soil, the fiber length is 12 mm.
[0021] A preferred embodiment of the above technical solution is that the cement content is 15% of the weight of the excavated soil, the polypropylene fiber content is 0.4% of the weight of the excavated soil, and the fiber length is 12 mm.
[0022] A shallow reinforcement device for soil around a pile comprises a soil taking device, a soil transport device, a polypropylene fiber cement soil container, a polypropylene fiber feeder, a cement feeder, a water feeder and a stirring device; the soil taking device is used to excavate the shallow soil around the pile according to the above excavation volume, the soil transport device is used to transport the soil excavated by the soil taking device and put it into the polypropylene fiber cement soil container, the polypropylene fiber feeder, the cement feeder and the water feeder are used to respectively put polypropylene fiber, cement and water into the polypropylene fiber cement soil container according to the above mixing ratios, and the stirring device is used to stir the materials in the polypropylene fiber cement soil container into polypropylene fiber cement soil and backfill it around the pile.
[0023] The above-mentioned shallow soil reinforcement device around the pile also includes a computer control system and a tamping device. The computer control system is used to monitor the weight in the polypropylene fiber cement soil container in real time and monitor the weight of the input polypropylene fiber and cement.
[0024] The compacting device is used for compacting the backfilled polypropylene fiber cement soil.
[0025] The beneficial effects of the present invention are:
[0026] The method of the present invention further adds an appropriate amount of polypropylene fiber to the soft soil on the basis of mixing cement slurry, so as to further improve the performance of the reinforced soil. The present invention theoretically analyzes the actual required bearing capacity of a single pile, defines the soil depth improvement coefficient and the width improvement coefficient, calculates the excavation width and depth of the shallow soil, and then obtains the amount of polypropylene fiber and cement according to the weight of the excavated soil, so as to realize the reinforcement of the shallow soil around the pile foundation, and effectively improve the bearing capacity of the pile foundation, solving the problem of insufficient bearing capacity of the transmission line pile foundation when passing through the soft soil area.
[0027] The device of the present invention does not require excessive manual intervention and has comprehensive self-protection, which can greatly improve construction safety and economic benefits and is of great significance to the safe operation of power transmission lines. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a schematic diagram of the device of the present invention;
[0029] Figure 2 This is a schematic diagram showing the effect of cement content on compressive strength;
[0030] Figure 3 is the effect of fiber length on compressive strength;
[0031] Figure 4 This is a schematic diagram showing the effect of fiber content on compressive strength;
[0032] In the figure: 1. soil taking device, 2. soil transport device, 3. polypropylene fiber cement soil container, 4. polypropylene fiber feeder, 5. cement feeder, 6. water feeder, 7. computer control system, 8. stirring device, 9. compacting device. DETAILED DESCRIPTION
[0033] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
[0034] Embodiment 1
[0035] like Figure 1 As shown, the shallow reinforcement device for soil around piles in this embodiment is as follows Figure 1 As shown, it includes a soil taking and feeding device 1, a soil transportation device 2, a polypropylene fiber cement soil container 3, a polypropylene fiber feeder 4, a cement feeder 5, a water feeder 6, a computer control system 7, a mixing device 8, and a compacting device 9. The soil taking device 1 is used to excavate the shallow soil around the pile. The soil transportation device 2 is used to transport the soil excavated by the soil taking device 1 and put it into the polypropylene fiber cement soil container 3. The polypropylene fiber feeder 4, the cement feeder 5 and the water feeder 6 are used to put polypropylene fiber, cement and water into the polypropylene fiber cement soil container 3 respectively. The mixing device 8 is used to mix the materials in the polypropylene fiber cement soil container 3 into polypropylene fiber cement soil and backfill it around the pile. The computer control system 7 is used to monitor the weight in the polypropylene fiber cement soil container in real time and monitor the weight of the polypropylene fiber and cement put in. The compacting device 9 is used to compact the backfilled polypropylene fiber cement soil.
[0036] The reinforcement method of this embodiment in conjunction with the above reinforcement device is:
[0037] Step 1: Determine the excavation volume of the shallow soil around the pile and the dosage of each material including polypropylene fiber cement soil.
[0038] The soil excavation size is calculated by equations (1) to (3):
[0039]
[0040] b=0.57D cem +1
[0041]
[0042] Where: F1 is the design value of pile bearing capacity, kN; F0 is the actual bearing capacity of the pile, kN; a is the depth improvement factor; b is the width improvement factor; D cem H is the ratio of the reinforcement width D to the pile diameter d, cem is the ratio of the reinforcement depth H to the pile diameter d; d is the pile diameter, m; V is the excavation volume of the shallow soil around the pile, m3 ; The value of H is 0.5m.
[0043] The designed cement content is 5%-25% of the weight of the excavated soil, and the polypropylene fiber content is 0.2%-0.6% of the weight of the excavated soil.
[0044] Step 2: Excavate and transport shallow soil;
[0045] The soil excavation device 1 is used to excavate the shallow soil around the pile, and the soil is transported to the polypropylene fiber cement soil container 3 through the soil transportation device 2.
[0046] Step 3: Add polypropylene fiber, cement and water;
[0047] The various materials are fed into the polypropylene fiber cement soil container 3 according to the determined dosage through the polypropylene fiber feeder 4, the cement feeder 5, and the water feeder 6, and the weight of the cement soil in the polypropylene fiber cement soil container 3 is controlled by the computer control system 7. When the weight of the cement soil reaches the required value, the polypropylene fiber feeder 4, the cement feeder 5, and the water feeder 6 are controlled to stop feeding.
[0048] Step 5: polypropylene fiber cement soil backfill;
[0049] The cement soil after feeding is mixed by a mixing device 8 to form polypropylene fiber cement soil; the polypropylene fiber cement soil is then backfilled around the pile, and finally the backfilled cement soil is compacted by a compacting device 9.
[0050] In this embodiment, by defining the soil depth enhancement coefficient and the soil width enhancement coefficient, the excavation width and depth of the shallow soil can be calculated, and then the dosage of polypropylene fiber and cement can be obtained according to the weight of the excavated soil.
[0051] Embodiment 2
[0052] The shallow reinforcement method of the soil around the pile in this embodiment is the same as that in the second embodiment, except that the dosage of polypropylene fiber and cement is different. In this embodiment, the dosage of cement is 20% of the weight of the excavated soil, and the dosage of polypropylene fiber is 0.2% of the weight of the excavated soil.
[0053] In another embodiment, the cement content can be 5%-15% of the weight of the excavated soil, and the polypropylene fiber content can be 0.4% of the weight of the excavated soil.
[0054] The fiber length of the polypropylene fiber in this embodiment is 6 mm-15 mm.
[0055] When the polypropylene fiber content is 0.2%-0.4% of the weight of the excavated soil, the fiber length is preferably 12 mm.
[0056] A preferred combination of this embodiment is: the cement content is 15% of the weight of the excavated soil, the polypropylene fiber content is 0.4% of the weight of the excavated soil, and the fiber length is 12 mm.
[0057] Application Examples
[0058] In this example, shallow reinforcement is performed on the soil around a reinforced concrete pile with a length of 11.3m and a diameter of 0.8m. The pile body concrete adopts C30 concrete and the steel bars in the pile adopt HRB400 steel bars. Without soil reinforcement, the horizontal bearing capacity characteristic value of the pile in silt soft soil is 22.79kN, and the horizontal ultimate bearing capacity of the pile is 54.21kN.
[0059] The excavation volume of the shallow soil around the pile is determined by the method of the present invention as follows:
[0060] In this example, the pile diameter is 0.8m, and the designed reinforcement volume V is 1, 2, and 3 times respectively. According to the above formula, the maximum value of ab and the D corresponding to the optimal reinforcement range can be determined. cem and H cem Then, the optimal reinforcement coefficients are obtained according to the different relationship between a and b. The optimal reinforcement range under different reinforcement volumes can be obtained. The specific values of the reinforcement range and its corresponding ab values are shown in Tables 1 and 2 below.
[0061] Table 1
[0062]
[0063] Table 2
[0064]
[0065] In this example, unconfined compressive strength tests were conducted on reinforced soil specimens with different cement content (5%, 10%, 15%, 20%), different fiber content (0.2%, 0.4%, 0.6%) and different fiber lengths (6mm, 9mm, 12mm, 15mm). The obtained specimen strengths are as follows: Figure 2 , Figure 3 and Figure 4 As shown:
[0066] Figure 2 (a), (b) and (c) are the effects of different cement content and fiber length on the unconfined compressive strength when the fiber content is 0.2%, 0.4% and 0.6%, respectively. Figure 3 (a), (b), (c) and (d) are the effects of different fiber lengths and fiber content on the unconfined compressive strength when the cement content is 5%, 10%, 15% and 20%, respectively. Figure 4(a), (b), (c) and (d) are the effects of different fiber content and cement content on the unconfined compressive strength when the fiber length is 6 mm, 9 mm, 12 mm and 15 mm, respectively.
[0067] According to the above three series of figures, it can be seen that for cement contents of 5%, 10%, and 15%, when the fiber content does not exceed 0.4%, the soil compressive strength increases linearly, and when the polypropylene fiber content is 0.2%-0.4% of the excavated soil weight and the fiber length is 12mm, the soil compressive strength is better. When the fiber content exceeds 0.4%, the strength of the reinforced soil will decrease, and when the fiber length exceeds 12mm, the strength of the reinforced soil will also decrease.
[0068] Therefore, according to the above figure, in this example, the final mix ratio of reinforced soil can be selected as 20% cement content and 0.2% fiber content; or 15% cement content, 0.4% fiber content and 12mm fiber length can be selected as the final mix ratio of reinforced soil.
[0069] By using a reinforced soil mix ratio of 15% cement content, 0.4% fiber content and 12 mm fiber length, in combination with the three excavation schemes in Table 2, and after reinforcement using the method of the present invention, the horizontal ultimate bearing capacity of the pile body is increased by 519%, 549% and 575% respectively, effectively improving the bearing capacity of the pile foundation.
[0070] The technical solutions of the present invention are not limited to the above-mentioned embodiments, and any technical solutions obtained by equivalent replacement methods fall within the scope of protection required by the present invention.
Claims
1. A shallow reinforcement method for soil around piles, characterized in that: The steps include: Step 1: Determine the reinforcement width D and depth H of the soil around the pile, and then obtain the shallow soil excavation volume: <h2 style=";text-align:left;direction:ltr">b = 0.57D<h2 style=";text-align:left;direction:ltr"> cem <h2 style=";text-align:left;direction:ltr"> +1 Where: F1 is the design value of pile bearing capacity; F0 is the actual bearing capacity of the pile; a is the depth improvement factor; b is the width improvement factor; D cem H is the ratio of the reinforcement width D to the pile diameter d, cem is the ratio of the reinforcement depth H to the pile diameter d; d is the pile diameter; V is the excavation volume of the shallow soil around the pile; Step 2: excavate shallow soil around the pile according to the reinforcement width D and reinforcement depth H obtained in step 1; The soil excavation and loading device (1) is used to excavate the shallow soil around the pile, and the soil is transported to the polypropylene fiber cement soil container (3) through the soil transport device (2). Step 3: Mix a certain amount of polypropylene fiber and cement into the excavated soil, and then add water and stir to prepare polypropylene fiber cement soil; Step 4: Backfill the prepared polypropylene fiber cement soil around the pile and compact it to reinforce the shallow layer of the soil around the pile.
2. The shallow reinforcement method of soil around piles according to claim 1, characterized in that: In the step 3, the cement content is 5%-25% of the weight of the excavated soil, and the polypropylene fiber content is 0.2%-0.6% of the weight of the excavated soil.
3. The shallow reinforcement method of soil around piles according to claim 2, characterized in that: The cement content is 20% of the weight of the excavated soil, and the polypropylene fiber content is 0.2% of the weight of the excavated soil.
4. The shallow reinforcement method of soil around piles according to claim 2, characterized in that: The cement content is 5%-15% of the excavated soil weight, and the polypropylene fiber content is 0.4% of the excavated soil weight.
5. The shallow reinforcement method of soil around piles according to claim 2, characterized in that: The fiber length of the polypropylene fiber is 6mm-15mm.
6. The shallow reinforcement method of soil around piles according to claim 5, characterized in that: When the polypropylene fiber content is 0.2%-0.4% of the weight of the excavated soil, the fiber length is 12 mm.
7. The shallow reinforcement method of soil around piles according to claim 6, characterized in that: The cement content is 15% of the weight of the excavated soil, the polypropylene fiber content is 0.4% of the weight of the excavated soil, and the fiber length is 12 mm.
8. A shallow reinforcement device for soil around a pile, characterized in that: The invention comprises a soil taking device (1), a soil transport device (2), a polypropylene fiber cement soil container (3), a polypropylene fiber feeder (4), a cement feeder (5), a water feeder (6) and a stirring device (8); the soil taking device (1) is used to excavate the shallow soil around the pile according to the excavation volume in the method according to any one of claims 2 to 7; the soil transport device (2) is used to transport the soil excavated by the soil taking device (1) and put it into the polypropylene fiber cement soil container (3); the polypropylene fiber feeder (4), the cement feeder (5) and the water feeder (6) are used to respectively put polypropylene fiber, cement and water into the polypropylene fiber cement soil container (3) according to the dosage in the method according to any one of claims 2 to 7; the stirring device (8) is used to stir the materials in the polypropylene fiber cement soil container (3) into polypropylene fiber cement soil and backfill it around the pile.
9. The shallow reinforcement device for soil around piles according to claim 1, characterized in that: The invention also comprises a computer control system (7), which is used for real-time monitoring of the weight in the polypropylene fiber cement soil container (3) and monitoring the weight of the polypropylene fiber and cement input.
10. The shallow reinforcement device for soil around piles according to claim 9, characterized in that: It also comprises a compacting device (9), wherein the compacting device (9) is used to compact the backfilled polypropylene fiber cement soil.