Slurry leakage preventing device of cast-in-place pile bulge structure and performance improving method

Abstract

The invention discloses a grout leakage preventing device of a cast-in-place pile bulge structure and a performance improving method, and relates to the technical field of bridge foundation engineering, the grout leakage preventing device comprises a reinforcement cage, a cast-in-place pile cloth bag, a lower canopy structure, an upper canopy structure and a pile body supporting and limiting device; the limiting grooves of the folding supporting rods are matched with the hinged elbows, the unfolding angle of the umbrella fabric fiber cloth is limited, and therefore the ultimate bearing capacity is improved; pile body supporting and limiting limit limits unfolding of the swing rods through the steel wire ropes, constraint of supporting disc expansion is achieved, the situation that a reinforcement cage enters a pile hole is not affected, low-slurry-leakage-rate and high-bearing-capacity pile foundation construction is achieved in a karst cave stratum, the size of the supporting disc is optimized through pile body supporting and limiting, economical efficiency and structural reliability are both considered, and the pile body supporting and limiting method is suitable for complex karst geological conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge foundation engineering, and particularly relates to a slurry leakage prevention device for a bored pile bulge structure and a performance improvement method. BACKGROUND

[0002] With the continuous advancement of infrastructure construction, complex geological conditions are often encountered in bridge engineering construction. Among them, the existence of underground karst cave brings great challenges to the construction and stability of bridge piles. The traditional bored pile technology often fails to effectively seal the karst cave when facing the karst cave, which easily causes problems such as large slurry loss, insufficient stability of the karst cave, and seriously affects the quality of the bridge pile and the safety of the project.

[0003] In order to solve this problem, the bored pile bag bulge structure is applied to the bored pile hole construction at the position of the underground karst cave. The structure forms a bulge structure at the position of the karst cave during the bored pile hole process, which can improve the stability of the karst cave, effectively seal the karst cave, reduce the use of slurry, and improve the construction efficiency and economy.

[0004] However, the slurry leakage rate during the construction process is more than 20%, and through testing, the end bearing capacity of the pile foundation is insufficient, and the ultimate bearing capacity is only 60%-80% of the design value.

[0005] Therefore, in view of the above phenomenon, a slurry leakage prevention device for a bored pile bulge structure and a performance improvement method are proposed to meet the needs of actual use. SUMMARY

[0006] The present application provides a slurry leakage prevention device for a bored pile bulge structure and a performance improvement method, which solves the technical problems of large slurry leakage probability and insufficient end bearing capacity of the pile foundation.

[0007] To solve the above technical problems, the present application provides a slurry leakage prevention device for a bored pile bulge structure and a performance improvement method, which includes a steel reinforcement cage, a bored pile bag, a lower umbrella cover structure, an upper umbrella cover structure, and a pile body support limit; the steel reinforcement cage is arranged in the pile hole of the bridge, the steel reinforcement cage includes a main reinforcement and a stirrup, the main reinforcement is fixed to the surface of the stirrup, the bored pile bag is cylindrical and wrapped around the surface of the steel reinforcement cage, and the upper and lower ends of the bored pile bag are located on the upper and lower sides of the karst cave, respectively; the lower umbrella cover structure and the upper umbrella cover structure are symmetrically arranged and are respectively arranged at the upper and lower junction positions of the pile hole and the karst cave of the bridge; the bored pile bag forms a branch disc at the cavity part of the karst cave, and the pile body support limit is arranged at the middle part of the branch disc.

[0008] In some embodiments, the lower umbrella cover structure and the upper umbrella cover structure each include an umbrella surface fiber cloth, a folding support rod, and a fixed base; the fixed base is detachably mounted on the main reinforcement, the folding support rod is fixed to the fixed base, and the umbrella surface fiber cloth is connected to the folding support rod.

[0009] In some embodiments, the folding support rod comprises a mounting bottom rod, a movable support rod and a hinged elbow; the mounting bottom rod and the movable support rod are hingedly connected to form a rotating pair connection, the hinged elbow is integrally formed at the hinged end of the movable support rod, the hinged end of the mounting bottom rod is provided with a limiting groove, the hinged elbow and the limiting groove are matched to mechanically limit the deflection angle of the movable support rod, and the umbrella fabric is fixedly connected with the movable support rod.

[0010] In some embodiments, the fixed base comprises a fixed crossbar and a fixed hoop, one side of the fixed crossbar is fixedly connected with the mounting bottom rod, the other side of the fixed crossbar is provided with at least two circular arc grooves matched with the main ribs, the distance between the two circular arc grooves is matched with the distance between the adjacent main ribs; the fixed hoop is wrapped on the surface of the main rib, the two ends of the fixed hoop penetrate through the fixed crossbar and are fixed by nuts, and the locking position of the fixed hoop is matched with the position of the circular arc groove on the fixed crossbar.

[0011] In some embodiments, the number of pile body support limiters is several, and the several pile body support limiters are evenly arrayed between the steel reinforcement cage and the cast-in-place pile bag.

[0012] In some embodiments, the pile body support limiter comprises a connecting fiber cloth, a swing rod and a steel wire rope, the connecting fiber cloth is connected with the cast-in-place pile bag, the first end of the swing rod is detachably connected with the hoop rib, the tail end of the swing rod is hingedly connected with the connecting fiber cloth, the first end of the steel wire rope is connected with the hoop rib of the steel reinforcement cage, and the tail end of the steel wire rope is connected with the tail end of the swing rod.

[0013] In some embodiments, the swing rod comprises a rod body, a connecting support, a hinged support and a connecting seat, the connecting support is wrapped on the surface of the hoop rib, the connecting support is fixed at the first end of the rod body by a nut, the hinged support is connected with the tail end of the connecting fiber cloth through a hinge shaft, the connecting seat is fixed on the rod body, the tail end of the steel wire rope is connected with the connecting seat through a lock head, and the first end of the steel wire rope is connected with the hoop rib of the steel reinforcement cage through a rope clamp.

[0014] In some embodiments, the steel reinforcement cage, the swing rod and the unfolded steel wire rope form a triangular structure to limit the movement of the connecting fiber cloth.

[0015] The method provided by the application specifically comprises the following steps:

[0016] S1: Karst cave height measurement: determine the height and spatial distribution of the Karst cave section through exploration;

[0017] S2: component layout: according to the height and position of the Karst cave, the lower umbrella cover structure and the upper umbrella cover structure are respectively installed at the upper and lower junction positions of the pile hole and the Karst cave of the bridge, and the pile body support limiter is installed at the middle part of the Karst cave section.

[0018] S3: Installation of the cast-in-place pile bag: The cast-in-place pile bag is sleeved on the surface of the reinforcement cage, so as to completely cover the lower umbrella cover structure, the upper umbrella cover structure and the pile body support limit;

[0019] S4: Branch plate forming control: when the concrete is poured, the cast-in-place pile bag is made to expand radially at the cavity part of the karst cave through the pouring pressure control, so as to form a branch plate with a diameter D, and the diameter D is limited by the pile body support limit, wherein D = pile diameter d x (1.5-2.0);

[0020] S5: Umbrella bearing cooperation: the umbrella surface fiber cloth of the lower umbrella cover structure and the upper umbrella cover structure respectively forms a bearing surface with the bottom and top rock mass of the karst cave, and the vertical load is borne together with the branch plate.

[0021] In some embodiments, the step S3 comprises:

[0022] The cast-in-place pile bag is connected with the umbrella surface fiber cloth of the lower umbrella cover structure and the upper umbrella cover structure and the connecting fiber cloth of the pile body support limit respectively, and the upper and lower ends of the cast-in-place pile bag are fixed on the main reinforcement of the reinforcement cage at a position 2-3 m away from the boundary of the karst cave.

[0023] Compared with the related art, the anti-slurry-leakage device and performance improvement method of the cast-in-place pile bulging structure provided by the application have the following beneficial effects:

[0024] The anti-slurry-leakage device and performance improvement method of the cast-in-place pile bulging structure provided by the application limit the unfolding angle of the umbrella surface fiber cloth through the cooperation of the limiting slot of the folding support rod and the hinged elbow, so as to improve the ultimate bearing capacity; the pile body support limit limits the unfolding of the swing rod through the steel wire rope, so as to realize the constraint of the branch plate expansion, and does not affect the entering of the reinforcement cage into the pile hole, so as to realize the pile foundation construction with low slurry leakage rate and high bearing capacity in the karst stratum, the size of the branch plate is optimized through the pile body support limit, the economic efficiency and structural reliability are taken into account, and the method is suitable for complex karst geological conditions. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall cross-sectional structure of the application;

[0026] Figure 2 It is a schematic diagram of the lower umbrella cover structure of the application;

[0027] Figure 3 It is a schematic diagram of the lower umbrella cover structure of the application;

[0028] Figure 4 It is a schematic diagram of the pile body support limit of the application;

[0029] Figure 5 It is a schematic diagram of the pile body support limit of the application;

[0030] Figure 6 Q-s curve diagram of the model bag pile and the Q-s curve diagram after adding the slurry leakage prevention device;

[0031] Figure 7 Pouring amount diagram after adding the slurry leakage prevention device.

[0032] In the figure, 1 is a steel reinforcement cage, 2 is a pouring pile bag, 3 is a lower umbrella cover structure, 4 is an upper umbrella cover structure, 5 is a pile body support limiting, 11 is a main reinforcement, 12 is a stirrup, 31 is an umbrella surface fiber cloth, 32 is a folding support rod, 33 is a fixed base, 321 is a mounting bottom rod, 322 is a movable support rod, 323 is a hinged elbow, 324 is a limiting groove, 331 is a fixed cross rod, 332 is a circular arc groove, 333 is a fixed hoop, 51 is a connecting fiber cloth, 52 is a swing rod, 53 is a steel wire rope, 521 is a rod body, 522 is a connecting support, 523 is a hinged support, and 524 is a connecting seat. DETAILED DESCRIPTION

[0033] Example 1

[0034] The embodiment provides a slurry leakage prevention device for a pouring pile bulging structure, which solves the problems of slurry leakage and incomplete pile body in the pouring process of concrete and improves the bearing capacity of the pile foundation by arranging the slurry leakage prevention device. Figures 1-5 As shown in the figure, the present application comprises:

[0035] The steel reinforcement cage 1 comprises a main reinforcement 11 and a stirrup 12, has a total length of 27.56 meters (26 meters of pile length + extension of karst cave section), is hoisted and spliced in three sections, each section has a length of ≤9.2 meters, and is connected by field welding;

[0036] The pouring pile bag 2 is made of a T700 carbon fiber woven film bag, wraps the surface of the steel reinforcement cage 1, and extends to the boundary of the karst cave by 2-3 meters at the upper and lower ends as a joint; the length L of the pouring pile bag 2 is H+6 meters, wherein H is the height of the karst cave; for example, for a 5-meter-high karst cave, the pouring pile bag 2 needs to be 11 meters long.

[0037] The lower umbrella cover structure 3 and the upper umbrella cover structure 4 each comprise an umbrella surface fiber cloth 31, a folding support rod 32, and a fixed base 33; the fixed base 33 is detachably mounted on the main reinforcement 11, the folding support rod 32 is fixed on the fixed base 33, and the umbrella surface fiber cloth 31 is connected with the folding support rod 32.

[0038] The folding support rod 32 comprises a mounting bottom rod 321 and a movable support rod 322; the mounting bottom rod 321 is connected with the main reinforcement 11 through the fixed base 33; the movable support rod 322 is hinged with the mounting bottom rod 321 and is mechanically limited through a limiting groove 324; and the unfolding angle θ is adjusted according to the edge structure of the karst cave (30°-60°).

[0039] The fixed base 33 includes a fixed crossbar 331 and a fixed hoop 332, which are locked to the main reinforcement 11 by nuts. The fixed base 33 can also be directly fixed to the main reinforcement 11 by welding.

[0040] Implementation steps:

[0041] S1: Measure the height of the cave as H, the position of the upper and lower boundaries of the cave (H1 is the depth of the cave top, H2 = H1 + H), and draw a three-dimensional morphological diagram of the cave cavity;

[0042] S2: Tie the main reinforcement 11 and stirrups 12 according to the design to form a steel cage 1 with a total length of 27.56 meters (divided into 3 sections, each section ≤9.2m). Mark the umbrella installation position on the main reinforcement of the karst cave section (i.e., the range from H1 to H2); the fixing base (33) of the lower umbrella structure 3 is installed at depth H1; the fixing base 33 of the upper umbrella structure 4 is installed at depth H2.

[0043] S3: Place the 2-bag of the cast-in-place pile outside the steel cage 1. The upper and lower ends are fixed to the main reinforcement 11 by 304 stainless steel U-shaped buckles. The spacing of the U-shaped buckles is ≤30cm. The bag is sewn with double-line locking edges to the umbrella fiber cloth 31. Epoxy resin is applied to the joint and squeezed to compact it by the pressure of concrete pouring.

[0044] S4: Pour concrete, and use pressure to expand the pile bag 2 in the cavity of the karst cave to a diameter D = pile diameter d × (1.5-2.0);

[0045] S5: Umbrella-like load-bearing coordination: The umbrella fiber cloth 31 of the lower umbrella structure 3 and the upper umbrella structure 4 form a bearing surface with the bottom and top rock mass of the cave, respectively, and together with the support plate, they bear the vertical load.

[0046] The concrete used is C35 to C45; the aggregate size is ≤25mm to prevent puncture of the cloth bag.

[0047] Static load test: such as Figure 6 As shown, the Qs curve of the model bag pile indicates that its ultimate bearing capacity is 4.5 kN, while the Qs curve of this device indicates that its ultimate bearing capacity is 6.5 kN. This demonstrates that the device significantly improves bearing capacity. The main reason is that the upper umbrella structure 4 and the lower umbrella structure 3 of this device bear a portion of the load, allowing a larger area of ​​bedrock to share the pressure transmitted from the pile, thus reducing the compressive deformation of the bedrock.

[0048] Example 2

[0049] Based on Example 1, such as Figures 4-5As shown, the embodiment further comprises pile body support limiting part 5, which comprises connecting fiber cloth 51, swing rod 52 and steel wire rope 53, connecting fiber cloth 51 is stitched with cast-in-place pile cloth bag 2, swing rod 52 is hinged with stirrup 12 through connecting support 522, steel wire rope 53 is connected with stirrup 12, after pouring concrete into cast-in-place pile cloth bag 2, cast-in-place pile cloth bag 2 expands radially at the cavity cavity part, thereby driving connecting fiber cloth 51 to pull swing rod 52 to expand outward, the expansion angle of swing rod 52 is limited through steel wire rope 53, thereby limiting the size of the formed branch plate diameter D. Pile body support limiting part 5 is installed in the middle of the cave section.

[0050] The number of pile body support limiting parts 5 is several, and the several pile body support limiting parts 5 are evenly arrayed between steel reinforcement cage 1 and cast-in-place pile cloth bag 2.

[0051] Swing rod 52 comprises rod body 521, connecting support 522, hinged support 523 and connecting seat 524, connecting support 522 is wrapped on the surface of stirrup 12, connecting support 522 is fixed at the first end of rod body 521 through a nut, hinged support 523 is connected with the end of connecting fiber cloth 51 through a hinge shaft, connecting seat 524 is fixed on rod body 521, the end of steel wire rope 53 is connected with connecting seat 524 through a lock head, and the first end of steel wire rope 53 is connected with stirrup 12 of steel reinforcement cage 1 through a rope clamp.

[0052] Steel reinforcement cage 1, swing rod 52 and expanded steel wire rope 53 form a triangular structure to limit the movement of connecting fiber cloth 51.

[0053] In an implementation process, the pile body parameters are as follows:

[0054] Pile diameter d=1.8m, pile length L=26m, depth H1=15m, height H=5m (cave range 15-20m), when the expansion ratio is 1.5, the branch plate expansion diameter D=2.7m;

[0055] Theoretical pouring amount calculation:

[0056] Pile body theoretical volume:

[0057] V 桩 =π×(0.9) 2 ×26=66.25m 3

[0058] The branch plate forms a column under the limitation of cast-in-place pile cloth bag 2, and the branch plate theoretical volume is:

[0059] V 盘 =π×(1.35) 2 ×5-π×(0.9) 2 ×5=15.90m 3

[0060] Total theoretical volume:

[0061] V 理论 =V 桩 +V 盘 =82.15m 3

[0062] like Figure 7 The figure shows the actual grouting volume after adding the anti-leakage grouting device. The results show that the actual grouting volume was 87m³. 3 The calculation yields a filling coefficient of 1.06, which reduces the amount of concrete used while improving the ultimate bearing capacity, effectively increasing the strength of the pile body and reasonably controlling costs.

[0063] In this embodiment, by adding a pile support limit 5, the size of the support plate is limited, the amount of concrete used is reduced, and the loss of grout is avoided, which would cause excessive consumption and waste.

[0064] Through multiple experiments, it was found that adding a grout leakage prevention device reduced the grout leakage rate from about 20% to below 5%, thus ensuring the construction quality.

Claims

1. A grout leakage prevention device for a bulging structure of a cast-in-place pile, characterized in that, The system includes a reinforcing cage, a cast-in-place pile bag, a lower umbrella structure, an upper umbrella structure, and a pile body support and limiting device. The reinforcing cage is installed in the pile hole of the bridge and includes main bars and stirrups. The main bars are fixed to the surface of the stirrups. The cast-in-place pile bag is cylindrical and wraps around the surface of the reinforcing cage. The upper and lower ends of the cast-in-place pile bag are located on the upper and lower sides of the karst cave, respectively. The lower umbrella structure and the upper umbrella structure are symmetrically arranged and are respectively located at the upper and lower junctions of the bridge pile hole and the karst cave. The cast-in-place pile bag forms a support plate in the cavity of the karst cave, and the pile body support and limiting device is located in the middle of the support plate.

2. The anti-leakage device for the bulge structure of a cast-in-place pile according to claim 1, characterized in that, Both the lower and upper umbrella structures include an umbrella fabric, a folding support rod, and a fixed base. The fixed base is detachably mounted on the main rib, the folding support rod is fixed to the fixed base, and the umbrella fabric is connected to the folding support rod.

3. The anti-leakage device for the bulge structure of a cast-in-place pile according to claim 2, characterized in that, The folding support rod includes a mounting base rod, a movable support rod, and a hinged elbow. The mounting base rod and the movable support rod are hinged to each other to form a rotating joint. The hinged elbow is integrally formed at the hinged end of the movable support rod. A limit groove is provided at the hinged end of the mounting base rod. The mechanical limit of the deflection angle of the movable support rod is achieved by the contour matching of the hinged elbow and the limit groove. The umbrella fiber cloth is fixedly connected to the movable support rod.

4. The anti-leakage device for the bulge structure of a cast-in-place pile according to claim 3, characterized in that, The fixed base includes a fixed crossbar and a fixed hoop. One side of the fixed crossbar is fixedly connected to the mounting base bar, and the other side of the fixed crossbar has at least two arc grooves that match the main reinforcement bars. The distance between the two arc grooves matches the distance between adjacent main reinforcement bars. The fixed hoop covers the surface of the main reinforcement bars, and both ends of the fixed hoop pass through the fixed crossbar and are fixed by nuts. The locking position of the fixed hoop matches the position of the arc grooves on the fixed crossbar.

5. The anti-leakage device for the bulge structure of a cast-in-place pile according to claim 1, characterized in that, The number of pile body support limiters is several, and the several pile body support limiters are evenly arrayed between the steel cage and the cast-in-place pile bag.

6. A grout leakage prevention device for a bulging structure of a cast-in-place pile according to claim 5, characterized in that, The pile support limiter includes a connecting fiber cloth, a swing rod, and a steel wire rope. The connecting fiber cloth is connected to the grouting pile bag. The first end of the swing rod is detachably connected to the stirrup. The end of the swing rod is hinged to the connecting fiber cloth. The first end of the steel wire rope is connected to the stirrup of the reinforcing cage. The end of the steel wire rope is connected to the end of the swing rod.

7. A grout leakage prevention device for a bulging structure of a cast-in-place pile according to claim 6, characterized in that, The swing rod includes a rod body, a connecting support, a hinged support, and a connecting seat. The connecting support covers the surface of the stirrups and is fixed to the head end of the rod body by a nut. The hinged support is connected to the end of the connecting fiber cloth through a hinge shaft. The connecting seat is fixed to the rod body. The end of the wire rope is connected to the connecting seat through a lock head, and the head end of the wire rope is connected to the stirrups of the reinforcing cage through a rope clamp.

8. A grout leakage prevention device for a bulging structure of a cast-in-place pile according to claim 6, characterized in that, The steel cage, swing rod, and deployed steel wire rope form a triangular structure that restricts the movement of the connecting fiber cloth.

9. A method for improving the performance of a grout leakage prevention device using a bulge structure of a cast-in-place pile as described in any one of claims 1 to 8, characterized in that, Specifically, the following steps are included: S1: Cave height measurement: Determine the height and spatial distribution of cave sections through exploration; S2: Component layout: Based on the height and location of the karst cave, the lower umbrella structure and the upper umbrella structure are respectively installed at the junction of the bridge pile hole and the upper and lower parts of the karst cave, and the pile body support limit is installed in the middle of the karst cave section; S3: Installation of the pile bag: Place the pile bag on the surface of the reinforcing cage so that it completely covers the lower umbrella structure, the upper umbrella structure and the pile support limit; S4: Support plate forming control: During concrete pouring, the pouring pressure is controlled to cause the pile bag to expand radially in the cavity of the karst cave, forming a support plate with a diameter of D. Under the constraint of the pile body support limit, where D = pile diameter d × (1.5~2.0). S5: Umbrella-like load-bearing coordination: The fiber cloth of the lower umbrella structure and the upper umbrella structure forms a load-bearing surface with the rock mass at the bottom and top of the cave, respectively, and together with the support plate, they bear the vertical load.

10. A method for improving the performance of a grout leakage prevention device for a bulging structure of a cast-in-place pile according to claim 9, characterized in that, Step S3 includes: Connect the pile bag to the umbrella fiber cloth of the lower and upper umbrella structures and the connecting fiber cloth of the pile body support and limit; fix the upper and lower ends of the pile bag to the main reinforcement of the steel cage 2-3m outside the boundary of the karst cave.

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