A method for vibration sinking of a stone column pipe

Abstract

The application discloses a method for vibrating and sinking a pile pipe of a gravel pile, and comprises the following steps: step one, using a vibration hammer on a gravel pile ship to sink the pile pipe into the soil; step two, when the bottom of the pile pipe meets the soil with a larger compactness, and the vibration hammer cannot continue to sink the pile pipe to the design elevation even after reaching the maximum power of the equipment, calculating the additional vibration mass F 额 , that is, calculating the weight of the gravel to be filled into the pile pipe in advance; step three, filling the gravel with the weight of the additional vibration mass F 额 into the pile pipe; step four, continuing to use the vibration hammer to sink the pile pipe until the pile pipe is sunk to the design bottom elevation; and step five, adding the remaining gravel M 桩管 -F 额 into the pile pipe, and then performing a subsequent pipe pulling process. The gravel filled into the pile pipe in advance increases the vibration mass, so that the purpose of improving the penetration of the pile pipe in the pile sinking process is achieved.

Description

Technical Field

[0001] This invention relates to a method for vibrating and sinking crushed stone pile pipes. Background Technology

[0002] Crushed stone piles are increasingly used in foundation reinforcement projects because they can increase the relative compaction and dry density of soil, thereby improving the soil's bearing capacity and liquefaction resistance. They also form vertical drainage channels under load and are relatively quick to install. The crushed stone pile method, when used in construction, provides replacement, compaction, and vibration compaction to the soil layers. The piles and the soil between them form a composite foundation, increasing bearing capacity, reducing deformation, and eliminating soil liquefaction. This makes it particularly suitable for large-scale foundation treatment after land reclamation. With a crushed stone pile composite foundation, the characteristic bearing capacity of the foundation can reach 180 kPa.

[0003] With the increase in the power of vibratory hammers and the development of specialized stone crushing pile equipment, driven stone crushing piles are showing a trend of longer pile lengths, larger pile diameters, and higher replacement rates. For example, in a land reclamation project in Zhoushan, the designed pile diameter is 1m and the pile length is 40m.

[0004] The construction process of crushed stone piles is divided into three stages: pile driving, material feeding, and pile extraction. The pile driving stage involves using vibratory driving equipment (usually a hydraulic or electric vibratory hammer) to drive the pile casing to the designed pile bottom elevation. Before construction begins, the construction unit will select the vibratory hammer based on design parameters such as geological conditions, pile diameter, and pile length, including selecting parameters such as power, excitation force, and eccentricity. However, during construction, local soil compaction often occurs, making it impossible for the vibratory hammer to drive the pile casing to the designed elevation even when it reaches its maximum power. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a vibratory driving method for crushed stone pile tubes. By filling the pile tube with crushed stone material in advance, the vibration weight is increased, thereby increasing the penetration of the pile tube during the pile driving process.

[0006] The objective of this invention is achieved as follows: a method for vibrating and sinking crushed stone pile tubes, comprising the following steps:

[0007] Step 1: Use the vibratory hammer on the stone pile boat to drive the pile pipe into the soil.

[0008] Step two: When the bottom of the pile encounters soil with increased density, making it impossible for the vibratory hammer to continue driving the pile to the design elevation even after reaching its maximum power, calculate the additional vibratory weight F required. 额 That is, to calculate the weight of the crushed stone that needs to be filled into the pile pipe in advance;

[0009] For the vibratory hammer to drive the pile into the soil, the following inequality (1) must be satisfied:

[0010] Downward force F 下 > Upward force F 上 (1)

[0011] F 下 = Pipe driving excitation force + non-vibrational weight of vibratory hammer + weight of pile casing;

[0012] F 上 = Dynamic side frictional resistance + Moving end resistance + Buoyancy;

[0013] The excitation force for pile driving is generated by the vibrating mass of the vibratory hammer. When the vibratory hammer reaches its maximum power, the excitation force for pile driving also reaches its maximum value. The non-vibrating weight of the vibratory hammer is an inherent parameter of the vibratory hammer itself. The weight of the pile pipe is a fixed value after the diameter and length of the pile pipe are determined.

[0014] The dynamic side friction resistance is calculated according to the following formula (2):

[0015] TV (侧) =up×(Ψsi×qsia1×ls1+Ψsi×qsia2×ls2) (2)

[0016] In formula (2), TV (侧) t represents the dynamic side friction resistance; up represents the outer perimeter of the pile pipe (m); Ψsi represents the diameter side friction effect coefficient, selected according to Table 5-18 of the Concise Construction Calculation Manual, with Ψsi=1; qsia1 represents the dynamic side friction resistance of the first layer of soil below the mud surface (kPa), based on the reference value of dynamic side friction resistance from PTC France, considering the combined value of internal and external dynamic side friction resistance, referring to precast piles, and according to Table 5-15 of the Concise Construction Calculation Manual, qsia1 is multiplied by a correction factor of 1.2; ls1 represents the thickness of the first layer of soil below the mud surface (m); qsia2 represents the dynamic side friction resistance of the second layer of soil below the mud surface (kPa); ls2 represents the thickness of the second layer of soil below the mud surface (m).

[0017] The moving end resistance is calculated according to the following formula (3):

[0018] (3)

[0019] In formula (3), denoted as φ, where is the moving end resistance; N is the standard penetration test blow count; e is the natural constant; φ is a constant, taken as 0.0652; and S is the base area of ​​the pile casing (cm²). 2 I represents the vibration impulse exerted by the vibratory hammer on the soil at the bottom of the pile pipe, calculated according to the following formula (4):

[0020] (4)

[0021] In formula (4), k is the eccentricity of the vibratory hammer (kg·m); w is the angular velocity of the vibratory hammer (rad / s); and g is the acceleration due to gravity. ;

[0022] The buoyancy is directly proportional to the volume of the pile pipe;

[0023] F 浮 = V×ρ×g; V is the volume of the crushed stone pile (m). 3 ρ is the density of water, 1000 kg / m³. 3 g is the acceleration due to gravity. ;

[0024] When F 下 <F 上 At this time, the pile pipe will not be able to be vibrated to the design bottom elevation, and an additional vibration weight F will be required. 额 =F 上 -F 下 ;

[0025] Calculate the total weight M of the crushed stone used to fill the pile pipe in one go. 桩管 =L 桩 ×π×r 2 × Crushed stone density; L 桩 is the length of the pile pipe; r is the inner diameter of the pile pipe;

[0026] Step 3: Fill the pile pipe with a weight equal to the additional vibration weight F. 额 The corresponding crushed stone material;

[0027] Step 4: Continue to use a vibratory hammer to drive the pipe pile until the pipe pile is driven to the design bottom elevation;

[0028] Step 5: Add the remaining crushed stone material = M into the pile pipe. 桩管 -F 额 Then proceed with the subsequent tube removal procedure.

[0029] The above-mentioned vibratory driving method for crushed stone pile pipes, wherein, during step two, if F 额 >M 桩管 This indicates that the vibratory hammer was selected incorrectly and a higher-powered vibratory hammer should be used instead.

[0030] The above-mentioned vibratory driving method for crushed stone pile pipes, wherein, during step three, if F 额 =M 桩管 The total weight M of crushed stone that is filled into the pile pipe in one go to completely fill the pile pipe. 桩管 .

[0031] The vibratory driving method for crushed stone pile tubes of the present invention has the following characteristics:

[0032] 1. During the vibratory driving of crushed stone piles, when the vibratory hammer reaches its maximum power and the penetration amount no longer increases, that is, before the pile tip reaches the design bottom elevation, crushed stone is filled into the pile pipe in advance, which increases the vibration weight and achieves the purpose of increasing the penetration amount of the pile pipe during the pile driving process, so that the pile pipe can be driven into the design bottom elevation smoothly.

[0033] 2. By utilizing the pile material itself to increase the vibration weight, there is no additional construction cost or time, and the operation is simple and convenient. Attached Figure Description

[0034] Figure 1 This is a state diagram of step one in the vibratory driving method for the crushed stone pile tube of the present invention;

[0035] Figure 2 This is a state diagram of step three in the vibratory driving method for the crushed stone pile pipe of the present invention;

[0036] Figure 3 This is a state diagram of step four in the vibratory driving method for the crushed stone pile pipe of the present invention. Detailed Implementation

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] Please see Figures 1 to 3 The vibratory driving method for crushed stone pile pipes of the present invention includes the following steps:

[0039] Step 1: Use the vibratory hammer 10 on the stone pile boat 1 to drive the pile pipe 2 into the soil (see...) Figure 1 );

[0040] Step two: When the bottom of the pile encounters soil with increased density, making it impossible for the vibratory hammer to continue driving the pile to the design elevation even after reaching its maximum power, calculate the additional vibratory weight F required. 额 That is, to calculate the weight of the crushed stone material that has been pre-filled into the pile pipe;

[0041] For a vibratory hammer to drive the pile into the soil, the following inequality (1) must be satisfied:

[0042] Downward force F 下 > Upward force F 上 (1)

[0043] F 下 = Pipe driving excitation force + non-vibrational weight of vibratory hammer + weight of pile casing;

[0044] F 上 = Dynamic side frictional resistance + Moving end resistance + Buoyancy;

[0045] The excitation force for pile driving is generated by the vibrating mass of the vibratory hammer. When the vibratory hammer reaches its maximum power, the excitation force for pile driving also reaches its maximum value. The non-vibrating weight of the vibratory hammer is an inherent parameter of the vibratory hammer itself. The weight of the pile pipe is a fixed value after the diameter and length of the pile pipe are determined.

[0046] The dynamic side friction resistance is calculated according to the following formula (2):

[0047] T V(侧) =up×(Ψsi×qsia1×ls1+Ψsi×qsia2×ls2) (2)

[0048] In formula (2), T V(侧) t represents the dynamic side friction resistance; up represents the outer perimeter of the pile pipe (m); Ψsi represents the diameter side resistance effect coefficient, selected according to Table 5-18 of the Concise Construction Calculation Manual, with Ψsi=1; qsia1 represents the dynamic side friction resistance of the first soil layer below the mud surface (kPa), based on the reference value of dynamic side friction resistance from PTC France (see Selected Vibratory Hammer Data https: / / www.taodocs.com / p-779676560.html, or see Vibratory Hammer Selection https: / / www.doc88.com / p-94559773470361.html?r=1), considering the combined value of internal and external dynamic side friction resistance, referring to precast piles, according to Table 5-15 of the Concise Construction Calculation Manual, qsia1 is multiplied by a correction factor of 1.2; ls1 represents the thickness of the first soil layer below the mud surface (m); qsia2 represents the dynamic side friction resistance of the second soil layer below the mud surface (kPa); ls2 represents the thickness of the second soil layer below the mud surface (m).

[0049] The moving end resistance is calculated according to the following formula (3):

[0050] (3)

[0051] In formula (3), denoted as φ, where is the moving end resistance; N is the standard penetration test blow count; e is the natural constant; φ is a constant, taken as 0.0652; and S is the base area of ​​the pile casing (cm²). 2 I represents the vibration impulse exerted by the vibratory hammer on the soil at the bottom of the pile pipe, calculated according to the following formula (4):

[0052] (4)

[0053] In formula (4), k is the eccentricity of the vibratory hammer (kg·m); w is the angular velocity of the vibratory hammer (rad / s); and g is the acceleration due to gravity. ;

[0054] Buoyancy F 浮 = V×ρ×g; V is the volume of the pile pipe in m³. 3 ρ is the density of water, taken as 1000 kg / m³.3 g is the acceleration due to gravity. ;

[0055] When F 下 <F 上 At this time, the pile pipe will not be able to be vibrated to the design bottom elevation, and an additional vibration weight F will be required. 额 =F 上 -F 下 ;

[0056] Calculate the total weight M of the crushed stone used to fill the pile pipe in one go. 桩管 =L 桩 ×π×r 2 × Crushed stone density; L 桩 is the length of the pile pipe; r is the inner diameter of the pile pipe;

[0057] If F 额 >M 桩管 This indicates that the vibratory hammer was selected incorrectly and a more powerful vibratory hammer should be used instead.

[0058] Step 3: Fill the pile pipe 2 with a weight equal to the additional vibration weight F. 额 The corresponding crushed stone 3, i.e., the weight of crushed stone 3 = F 额 If F 额 =M 桩管 That is, the total weight M of crushed stone that fills the pile pipe 2 in one go. 桩管 (See Figure 2 ); When filling the pile, the pile tip gate must be tightly closed to prevent the crushed stone material from overflowing;

[0059] Step 4: Continue to use the vibratory hammer 10 to drive the pile pipe 2 until it is driven to the design bottom elevation 4 (see...). Figure 3 );

[0060] Step 5: Add the remaining crushed stone material = M into pile pipe 2. 桩管 -F 额 Continue this process until the required quantity is met, then proceed with the subsequent tube removal process.

[0061] The present invention is illustrated by an example of a land reclamation project in Zhoushan: the diameter of the crushed stone pile is 1m and the length of the crushed stone pile is 40m; an electric vibratory hammer with a maximum power of 400kW is used, the maximum excitation force of the vibratory hammer is 207t; the non-vibration weight of the vibratory hammer is 5.9t; the length of the pile pipe is 47m, the outer diameter of the pile pipe is 1.0m, the wall thickness of the pile pipe is 25mm, and the weight of the pile pipe is 28t.

[0062] The dynamic skin friction is directly proportional to the surface area of ​​the pile casing and to the dynamic skin friction coefficient (the dynamic skin friction coefficient varies under different geological conditions; the coefficient is larger for denser soils). In this project site, the first layer of soil beneath the mud surface is grayish-yellow hydraulically filled sand, with a depth of 0-7.3m and a standard penetration test (SPT) blow count N=8. The second layer of soil beneath the mud surface is gray clay, with a depth of 7.3m-40m and an SPT blow count N=15. The SPT blow count N is the number of blows required to penetrate 30cm of soil by a 63.5kg vibratory hammer driven freely from a height of 76cm into the foundation (obtaining an approximate standard value for the bearing capacity of sand or cohesive soil on-site to evaluate the properties and bearing capacity of the foundation soil at this location).

[0063] The dynamic side friction resistance is calculated using equation (2):

[0064] T V(侧) =up×(Ψsi×qsia1×ls1+Ψsi×qsia2×ls2)=3.14×1.0×(1×13×1.2×7.3+1×15×1.2×32.7)=2205KN=220.5t

[0065] The moving end resistance is directly proportional to the soil density, directly proportional to the pile bottom area, and related to the eccentricity and rotational speed of the vibratory hammer.

[0066] The moving end resistance is calculated using equation (3). =28t

[0067] Buoyancy of the pile pipe

[0068] F 下 =Pile driving excitation force + Non-vibrational weight of vibratory hammer + Weight of pile casing = 240.9t

[0069] F 上 =Dynamic side frictional resistance + Moving end resistance + Buoyancy = 279.9t

[0070] Therefore, it can be seen that the downward-sinking force F 下 =240.9t is less than the upward resistance F 上 =279.9t. Under these circumstances, the pile pipe will not be able to be vibrated to the design bottom elevation, and an additional vibration weight of about 40t is required.

[0071] Based on a crushed stone density of 1.6 t / m³ -3 Calculate the total weight M of the crushed stone used to fill the pile pipe in one go. 桩管 :

[0072] M 桩管 = =54.47 t

[0073] M 桩管The total weight of the crushed stone used as filler for a single crushed stone pile is 54.5t;

[0074] When the vibratory hammer fails to drive the pile into the design elevation even after reaching its maximum power, 40t of crushed stone is first filled into the pile to increase the vibration weight and increase the penetration of the pile until it sinks to the design bottom elevation. Then, the remaining stone is filled into the pile: 54.5t - 40t = 14.5t.

[0075] Practice has proven that the method of increasing the penetration of crushed stone piles by adding material and vibration is effective.

[0076] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A method for vibratory driving of crushed stone pile casing, characterized in that, Includes the following steps: Step 1: Use the vibratory hammer on the stone pile boat to drive the pile pipe into the soil. Step two: When the bottom of the pile encounters soil with increased density, making it impossible for the vibratory hammer to continue driving the pile to the design elevation even after reaching its maximum power, calculate the additional vibratory weight F required. 额 That is, to calculate the weight of the crushed stone that needs to be filled into the pile pipe in advance; For the vibratory hammer to drive the pile into the soil, the following inequality (1) must be satisfied: Downward force F 下 > Upward force F 上 (1) F 下 = Pipe driving excitation force + non-vibrational weight of vibratory hammer + weight of pile casing; F 上 = Dynamic side frictional resistance + Moving end resistance + Buoyancy; The excitation force for pile driving is generated by the vibrating mass of the vibratory hammer. When the vibratory hammer reaches its maximum power, the excitation force for pile driving also reaches its maximum value. The non-vibrating weight of the vibratory hammer is an inherent parameter of the vibratory hammer itself. The weight of the pile pipe is a fixed value after the diameter and length of the pile pipe are determined. The dynamic side friction resistance is calculated according to the following formula (2): TV (侧) =up×(Ψsi×qsia1×ls1+Ψsi×qsia2×ls2) (2) In formula (2), TV (侧) t represents the dynamic side friction resistance; up represents the outer perimeter of the pile pipe (m); Ψsi represents the diameter side resistance effect coefficient, selected as Ψsi=1 according to Table 5-18 of the Concise Construction Calculation Manual; qsia1 represents the dynamic side friction resistance of the first soil layer below the mud surface (kPa), multiplied by a correction factor of 1.2; ls1 represents the thickness of the first soil layer below the mud surface (m); qsia2 represents the dynamic side friction resistance of the second soil layer below the mud surface (kPa); ls2 represents the thickness of the second soil layer below the mud surface (m). The moving end resistance is calculated according to the following formula (3): (3) In formula (3), denoted as φ, where is the moving end resistance; N is the standard penetration test blow count; e is the natural constant; φ is a constant, taken as 0.0652; and S is the base area of ​​the pile casing (cm²). 2 I represents the vibration impulse exerted by the vibratory hammer on the soil at the bottom of the pile pipe, calculated according to the following formula (4): (4) In formula (4), k is the eccentricity of the vibratory hammer (kg·m); w is the angular velocity of the vibratory hammer (rad / s); and g is the acceleration due to gravity. ; The buoyancy is directly proportional to the volume of the pile pipe; F 浮 = V×ρ×g; V is the volume of the pile pipe in m³. 3 ρ is the density of water, 1000 kg / m³. 3 g is the acceleration due to gravity. ; When F 下 <F 上 At this time, the pile pipe will not be able to be vibrated to the design bottom elevation, and an additional vibration weight F will be required. 额 =F 上 -F 下 ; Calculate the total weight M of the crushed stone used to fill the pile pipe in one go. 桩管 =L 桩 ×π×r 2 × Crushed stone density; L 桩 is the length of the pile pipe; r is the inner diameter of the pile pipe; Step 3: Fill the pile pipe with a weight equal to the additional vibration weight F. 额 The corresponding crushed stone material; Step 4: Continue to use a vibratory hammer to drive the pile pipe until it reaches the designed bottom elevation; Step 5: Add the remaining crushed stone material = M into the pile pipe. 桩管 -F 额 Then proceed with the subsequent tube removal procedure.

2. The vibratory driving method for crushed stone pile tubes according to claim 1, characterized in that, When performing step two, if F 额 >M 桩管 This indicates that the vibratory hammer was selected incorrectly and a higher-powered vibratory hammer should be used instead.

3. The vibratory driving method for crushed stone pile tubes according to claim 1, characterized in that, When performing step three, if F 额 =M 桩管 The total weight M of crushed stone that is filled into the pile pipe in one go to completely fill the pile pipe. 桩管 .

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