Anti-pulling device and method for reinforcement cage of full-pile-casing rotary excavating cast-in-place concrete pile

Abstract

The invention belongs to the technical field of cast-in-place pile construction, and particularly relates to a full-casing rotary excavating cast-in-place concrete pile reinforcement cage anti-pulling device and method.The device comprises a reinforcement cage, the reinforcement cage comprises main reinforcements, stirrups and reinforcing hoops, the device further comprises an anti-pulling steel plate, and the anti-pulling steel plate is arranged at the bottom of the reinforcement cage and welded to the reinforcement cage; the surface of the anti-pulling steel plate is parallel to the horizontal plane; the method is characterized in that the area of the anti-pulling steel plate is determined; compared with the prior art, the end resistance can be applied to the reinforcement cage, and the error-tolerant rate of the whole pile casing in the pulling state under the adverse working condition is increased through pressure. By analyzing the stress of the reinforcement cage, the method for calculating the size of the required steel plate is invented, and the problem of the size of the required steel plate under the condition of different hole depths is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bored pile construction technology, and particularly relates to a full casing rotary digging concrete bored pile reinforcement cage anti-pulling device and method. BACKGROUND

[0002] The full casing bored pile construction process has significant advantages in miscellaneous fill strata, but in the concrete pouring process, each section of the casing needs to be pulled out and disassembled multiple times until the casing is completely pulled out. Due to the interaction between the casing, the reinforcement cage and the concrete, the reinforcement cage is often pulled out, resulting in irreversible engineering quality problems. In order to avoid such problems, rework must be performed, resulting in cost losses and schedule delays during the full casing bored pile construction process. SUMMARY

[0003] The present application is directed to the deficiencies of the prior art, and a full casing rotary digging concrete bored pile reinforcement cage anti-pulling device and method can apply end resistance to the reinforcement cage, thereby increasing the fault tolerance of the full casing pulling state under adverse conditions. Through force analysis of the reinforcement cage, a method for calculating the required steel plate size is invented, solving the problem of the required steel plate size under different hole depths.

[0004] The technical solution for solving the technical problem of the present application is a full casing rotary digging concrete bored pile reinforcement cage anti-pulling device, which comprises a reinforcement cage, the reinforcement cage comprising main reinforcement, stirrups and reinforcing hoops, and further comprising an anti-pulling steel plate, the anti-pulling steel plate being arranged at the bottom of the reinforcement cage and being welded to the reinforcement cage, and the surface of the anti-pulling steel plate being arranged parallel to the horizontal plane.

[0005] As a preferred embodiment, the device further comprises an arc-shaped plate, the arc-shaped plate being rotatably connected to the bottom of the reinforcement cage.

[0006] As a preferred embodiment, the arc-shaped plates are arranged in an array.

[0007] As a preferred embodiment, a set of arc-shaped plates arranged opposite to each other are connected by a tension spring.

[0008] A full casing rotary digging concrete bored pile reinforcement cage anti-pulling method, comprising the following steps:

[0009] S1: hole forming and hole cleaning: full casing is used in combination with rotary digging to form a hole to the designed depth, the casing is kept through to the bottom of the hole or to the designed bottom elevation, and hole cleaning is performed until the thickness of the sediment at the bottom of the hole and the mud index meet the requirements of the specification;

[0010] S2: reinforcement cage assembly: a reinforcement cage comprising main reinforcement, stirrups and reinforcing hoops is made, the size of the anti-pulling steel plate is determined, the anti-pulling steel plate is welded to the bottom of the reinforcement cage, the plate surface of the anti-pulling steel plate is arranged parallel to the horizontal plane, and arc-shaped plates are installed around the bottom of the reinforcement cage;

[0011] S3: Lowering and positioning: The reinforcement cage is vertically hoisted and lowered into the hole, and the anti-pulling steel plate is located at the bottom of the hole;

[0012] S4: Anti-pulling control pouring: The guide pipe is embedded near the bottom of the hole, and the concrete is continuously poured from bottom to top through the guide pipe, so that the concrete first wraps the anti-pulling steel plate and pushes upward. The anti-pulling resistance formed by the anti-pulling steel plate wrapped by the concrete inhibits the upward floating of the reinforcement cage during pouring and subsequent pipe pulling;

[0013] S5: Cooperative pipe pulling: When the concrete surface exceeds the bottom of the casing, the casing is pulled out at a uniform speed, and the elevation of the reinforcement cage is continuously monitored until the pouring is completed.

[0014] As preferred, the specific method for determining the size of the anti-pulling steel plate in S2 is:

[0015] Calculate the weight of the reinforcement cage: G 钢筋笼 = m 钢筋笼 · g;

[0016] Calculate the volume of the reinforcement drainage: V 排 = V 钢筋 = (L·a·π·(R / 2 2 ) + (L / l1·π·(r1 / 2 2 ) + (L / l2·π·(r2 / 2 2 ) );

[0017] Calculate the buoyancy of the part of the reinforcement cage immersed in the concrete: F 浮 = ρ 混凝土 · g· V 排 + ΔP· A 桩 ;

[0018] Calculate the pressure on the anti-pulling steel plate: F 压 ≥ K 安全 *(F 浮 -G 钢筋笼 );

[0019] Calculate the area of the anti-pulling steel plate: S = F 压 / (ρ 混凝土 · g· h);

[0020] Where: L is the calculated height of the reinforcement cage, unit m; a is the number of main reinforcement, unit root; R is the diameter of the main reinforcement, unit m; l1 is the spacing of the stirrup, unit m; r1 is the diameter of the stirrup, unit m; l2 is the spacing of the reinforcing hoop, unit m; r2 is the diameter of the reinforcing hoop, unit m; g is the acceleration of gravity, unit N / m; h is the pouring height, unit m; ΔP is the negative pressure of quicksand (calculated by Darcy's law or measured on site, generally 30-60 kPa), unit kPa; A 桩 is the cross-sectional area of the pile, unit m 2 ; K​安全 For safety factor, take 1.5-2.

[0021] As preferred, the arc-shaped plate in S3 is unfolded to the horizontal plane after being below the reinforcement cage to exceed the full casing bottom elevation, further improving the uplift resistance of the reinforcement cage.

[0022] As preferred, the reinforcement cage elevation is continuously monitored in S5, and when the reinforcement cage floating trend is monitored, the deviation is corrected by measures such as slowing down the pipe pulling, adjusting the pouring speed or temporarily stopping pouring.

[0023] The effects provided in the summary are only the effects of the embodiments, not all the full effects of the invention, and the above technical solutions have the following advantages or beneficial effects:

[0024] 1. By setting the anti-pulling steel plate, end resistance is applied to the reinforcement cage, and the fault tolerance rate of the full casing lifting state under adverse working conditions is increased by pressure;

[0025] 2. By analyzing the stress of the reinforcement cage, a method for calculating the required steel plate size is invented, solving the problem of the required steel plate size under different hole depths;

[0026] 3. By setting the arc-shaped plate, the arc-shaped plate is retracted during the process of being below the reinforcement cage, which does not affect the reinforcement cage below, and when it is lowered to exceed the bottom elevation of the casing, the arc-shaped plate is unfolded under the action of gravity, and at the same time, due to the limitation of the tension spring, the unfolding angle is unfolded to the horizontal at most, which can further improve the uplift effect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the front view of the present application;

[0028] Figure 2 It is the overall structure of the present application Figure 1 ;

[0029] Figure 3 It is the overall structure of the present application Figure 2 ;

[0030] Figure 4 It is Figure 3 the local enlarged view of area A in the figure.

[0031] 1, reinforcement cage; 2, main reinforcement; 3, stirrup; 4, reinforcing hoop; 5, anti-pulling steel plate; 6, arc-shaped plate; 61, tension spring. DETAILED DESCRIPTION

[0032] In order to clearly illustrate the technical features of the present application, the present application will be described in detail below with specific embodiments, and combined with the accompanying drawings.

[0033] Example 1

[0034] Referring toFigures 1 to 4 A full casing rotary digging concrete bored pile steel reinforcement cage anti-pulling device, comprising a steel reinforcement cage 1, the steel reinforcement cage 1 comprising a main reinforcement 2, a stirrup 3 and a reinforcing hoop 4, further comprising an anti-pulling steel plate 5, the anti-pulling steel plate 5 being arranged at the bottom of the steel reinforcement cage 1 and welded with the steel reinforcement cage 1, the surface of the anti-pulling steel plate 5 being arranged in parallel with the horizontal plane, and the tensile strength of the anti-pulling steel plate 5 being not less than 200Mpa (for example, a Q235 steel plate).

[0035] Further comprising an arc-shaped plate 6, the arc-shaped plate 6 being rotationally connected at the bottom of the steel reinforcement cage 1.

[0036] The arc-shaped plates 6 are arranged in an array.

[0037] A set of arc-shaped plates 6 arranged oppositely are connected with a tension spring 61.

[0038] A full casing rotary digging concrete bored pile steel reinforcement cage anti-pulling method, comprising the following steps:

[0039] S1: hole forming and hole cleaning: full casing is adopted to cooperate with rotary digging to form a hole to a designed depth, the casing is kept through to the bottom of the hole or to a designed bottom elevation, and hole cleaning is performed until the thickness of the sediment at the bottom of the hole and the mud index meet the requirements of the specification;

[0040] S2: steel reinforcement cage 1 assembly: a steel reinforcement cage 1 comprising a main reinforcement 2, a stirrup 3 and a reinforcing hoop 4 is made, the size of an anti-pulling steel plate 5 is determined, the anti-pulling steel plate 5 is welded at the bottom of the steel reinforcement cage 1, the plate surface of the anti-pulling steel plate 5 is arranged in parallel with the horizontal plane, and arc-shaped plates 6 are installed around the bottom of the steel reinforcement cage 1;

[0041] S3: cage lowering and positioning: the steel reinforcement cage 1 is vertically hoisted and lowered into the hole, and the anti-pulling steel plate 5 is located at the bottom of the hole;

[0042] S4: anti-pulling controlled pouring: a guide pipe is embedded near the bottom of the hole, and concrete is continuously poured from bottom to top through the guide pipe, so that the concrete first wraps the anti-pulling steel plate 5 and then pushes upward, the anti-pulling resistance formed by the anti-pulling steel plate 5 being wrapped by the concrete inhibits the upward floating of the steel reinforcement cage 1 during pouring and subsequent pipe pulling;

[0043] S5: coordinated pipe pulling: after the concrete surface exceeds the bottom opening of the casing, the casing is uniformly pulled out, the elevation of the steel reinforcement cage 1 is continuously monitored, and the pouring is completed.

[0044] The specific method for determining the size of the anti-pulling steel plate 5 in S2 is as follows:

[0045] The weight of the steel reinforcement cage 1 is calculated: G 钢筋笼 = m 钢筋笼 · g;

[0046] The steel reinforcement liquid volume is calculated: V 排 = V 钢筋 = L· a· π· R / 2 2+L / l1·π·r1 / 2 2 +L / l2·π·r2 / 2 2 ;

[0047] Calculate the buoyancy of the steel cage 1 immersed in the concrete part: F 浮 =ρ 混凝土 ·g·V 排 +ΔP·A 桩 ;

[0048] Calculate the pressure on the anti-pull steel plate 5: F 压 ≥K 安全 *F 浮 -G 钢筋笼 ; In actual operation, the instantaneous pulling force of the rotary drilling rig may exceed the pressure on the anti-pull steel plate 5 under the influence of the proficiency of the rotary drilling driver and the overloaded working state of the rotary drilling rig. Through field practice testing, by increasing K 安全 , the fault tolerance of the full casing pulling under adverse conditions is increased;

[0049] Calculate the area of the anti-pull steel plate 5: S=F 压 / (ρ 混凝土 ·g·h);

[0050] Wherein: L is the calculated height of the steel cage 1, unit m; a is the number of main reinforcement 2, unit root; R is the diameter of the main reinforcement 2, unit m; l1 is the spacing of the stirrup 3, unit m; r1 is the diameter of the stirrup 3, unit m; l2 is the spacing of the reinforcing hoop 4, unit m; r2 is the diameter of the reinforcing hoop 4, unit m; g is the acceleration of gravity, unit N / m; h is the pouring height, unit m; ΔP is the flow sand negative pressure calculated by Darcy's law or measured on site, generally 30-60kPa, unit kPa; A 桩 is the cross-sectional area of the pile body, unit m 2 ; K 安全 is the safety factor, taken as 1.5-2.

[0051] The S3 arc-shaped plate 6 is unfolded to the horizontal plane below the steel cage to exceed the full casing bottom elevation, further improving the anti-pull ability of the steel cage 1.

[0052] The S5 continuously monitors the elevation of the steel cage 1, and when the steel cage 1 is found to be floating upward, measures such as slowing down the pipe pulling, adjusting the pouring speed or temporarily stopping pouring are taken to correct the deviation.

[0053] Although the specific embodiments of the present application have been described in conjunction with the accompanying drawings, they are not a limitation on the scope of protection of the present application. Various modifications or variations made by those skilled in the art without creative labor based on the technical solutions of the present application are still within the scope of protection of the present application.

Claims

1. A pull-out resistant device for a reinforcing cage of a rotary-drilled concrete pile with a full casing, comprising a reinforcing cage (1), wherein the reinforcing cage (1) comprises main bars (2), stirrups (3) and reinforcing hoops (4), characterized in that: It also includes a pull-out steel plate (5), which is set at the bottom of the reinforcing cage (1) and welded to the reinforcing cage (1). The surface of the pull-out steel plate (5) is set parallel to the horizontal plane.

2. The pull-out resisting device for the reinforcing cage of a rotary-drilled concrete pile with full casing as described in claim 1, characterized in that, It also includes an arc plate (6), which is rotatably connected to the bottom of the steel cage (1).

3. The pull-out resisting device for the reinforcing cage of a rotary-drilled concrete pile with full casing as described in claim 2, characterized in that, The arc-shaped plates (6) are arranged in an array.

4. The pull-out resisting device for the reinforcing cage of a rotary-drilled concrete pile with full casing as described in claim 3, characterized in that, A tension spring (61) connects a set of oppositely arranged arc-shaped plates (6).

5. A method for resisting the pull-out of the reinforcing cage of a rotary-drilled concrete pile with a full casing, characterized in that, Includes the following steps: S1: Hole Formation and Cleaning: Use full casing in conjunction with rotary drilling to form a hole to the design depth, keep the casing connected to the bottom of the hole or to the design bottom elevation, and clean the hole until the thickness of the sediment at the bottom of the hole and the mud index meet the specifications. S2: Assembly of steel cage (1): Fabricate a steel cage (1) including main bars (2), stirrups (3) and reinforcing hoops (4), determine the size of the pull-out steel plate (5), weld the pull-out steel plate (5) to the bottom of the steel cage (1), the plate surface of the pull-out steel plate (5) is set parallel to the horizontal plane, and install arc plates (6) around the bottom of the steel cage (1); S3: Lowering and positioning the cage: Vertically hoist the steel cage (1) into the hole so that the pull-out steel plate (5) is located at the bottom of the hole; S4: Pull-out control pouring: The guide pipe is buried near the bottom of the hole, and concrete is continuously poured from bottom to top through the guide pipe. The concrete first wraps around the pull-out steel plate (5) and pushes it upward. The pull-out resistance formed by the concrete wrapping the pull-out steel plate (5) inhibits the steel cage (1) from floating during the pouring and subsequent pipe pulling process. S5: Coordinated pipe pulling: When the concrete surface exceeds the bottom of the casing, pull out the casing at a uniform speed and continuously monitor the elevation of the steel cage (1) until the pouring is completed.

6. The method for resisting pull-out of the reinforcing cage of a rotary-drilled concrete pile with full casing as described in claim 5, characterized in that, The specific method for determining the dimensions of the pull-out steel plate (5) in S2 is as follows: Calculate the weight of the reinforcing cage (1): G 钢筋笼 =m 钢筋笼 ·g; Calculate the volume of liquid drained from the reinforcing steel: V 排 =V 钢筋 = (L·a·π·(R / 2)) 2 )+(L / l1·π·(r1 / 2) 2 )+(L / l2·π·(r2 / 2) 2 ); Calculate the buoyancy of the portion of the reinforcing cage (1) submerged in concrete: F 浮 =ρ 混凝土 ·g·V 排 +ΔP·A 桩 ; Calculate the pressure exerted on the pull-out steel plate (5): F 压 ≥K 安全 *(F 浮 -G 钢筋笼 ); Calculate the area of ​​the pull-out steel plate (5): S = F 压 / (ρ 混凝土 ·g·h); Where: L is the calculated height of the steel cage (1), in m; a is the number of main reinforcement bars (2), in bars; R is the diameter of the main reinforcement bars (2), in m; l1 is the spacing of the stirrups (3), in m; r1 is the diameter of the stirrups (3), in m; l2 is the spacing of the reinforcing stirrups (4), in m; r2 is the diameter of the reinforcing stirrups (4), in m; g is the acceleration due to gravity, in N / m; h is the pouring height, in m; ΔP is the negative pressure of quicksand, in kPa; A 桩 The cross-sectional area of ​​the pile is expressed in meters. 2 ;K 安全 This is for the safety factor.

7. The method for resisting pull-out of the reinforcing cage of a rotary-drilled concrete pile with full casing as described in claim 5, characterized in that, The arc plate (6) in S3 extends to the horizontal plane below the steel cage (1) after exceeding the bottom elevation of the entire casing, further improving the pull-out resistance of the steel cage (1).

8. The method for resisting pull-out of the reinforcing cage of a rotary-drilled concrete pile with full casing as described in claim 5, characterized in that, In S5, the elevation of the steel cage (1) is continuously monitored. When the upward trend of the steel cage (1) is detected, the deviation is corrected by measures such as slowing down the pipe pulling, adjusting the pouring speed, or temporarily stopping the pouring.

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