CN217974450U - Device for improving punching bearing capacity of rear steel pile-repairing raft plate - Google Patents

Abstract

The utility model discloses a device that is arranged in the basis to consolidate, mends steel pile raft board after improving and receives die-cut bearing capacity. The raft comprises a profile steel shear frame, a cross-shaped groove on a raft plate, a steel pipe pile top outer ring plate and a rear grouting steel pipe. Outer crown plate is welded at steel-pipe pile top, reserves the injected hole, after steel-pipe pile installation takes one's place, and upper portion opens the cross recess in raft board, and the cross recess cross-section is opened into down trapezoidal, and cross recess bottom width is greater than the shaped steel edge of a wing width to guarantee pouring of concrete and flow, the groove depth is greater than the shaped steel height. After the profile steel shear frame is installed in place, the raft top surface steel bars are connected through lap welding, then the fine aggregate concrete is poured, and after the concrete reaches the strength, post grouting is performed to improve the waterproof performance.

Description

Device for improving punching bearing capacity of rear steel pile-repairing raft plate

Technical Field

The utility model belongs to the technical field of the building, when being applicable to and adopting the piling bar to carry out the basis reinforcement, improve the die-cut bearing capacity that receives of raft board. For avoiding enlarging the area of opening a hole of pile foundation raft, reduce and destroy the former waterproof layer in raft bottom, avoid raft below groundwater and silt to gush into, after the pile-pressing, adopt the die-cut problem of raft is solved to newly-increased steel shear frame mode.

Background

The existing structure is often reinforced by post-pile-repairing method when increasing load, soaking and softening foundation soil and uneven settlement. The post-repair piles commonly used include cast-in-place concrete piles, static pressure steel columns, jet grouting piles and the like. The post-repairing steel pile has the advantages of wide application range, high pile body bearing capacity, high construction speed, small influence on the surrounding environment and wide application in the existing structural foundation reinforcement. However, because the strength of the steel is higher, the whole length of the compressive bearing capacity of the pile body is higher, and the section of the steel pile is relatively smaller. When the smaller pile body section is connected with the raft, the punched bearing capacity of the raft is always a difficult problem to the engineering.

The post-repair steel piles are applied for many years, and the cross sections of the commonly used steel piles comprise H-shaped steel piles, round pipe piles and the like, and are usually small, so that the construction is generally carried out in a static pressure mode. The common practice is to make holes on the top surface of the raft and press the steel piles into the holes by using a reaction frame. In order to save cost and reduce the broken and dismantled amount of the raft, the size of the opening is only slightly larger than the section of the pile. Common connection modes at the pile head position include an upper cover plate method, a reserved conical hole method, a local breaking and dismantling post-pouring method and the like.

The upper cover plate method is to set steel plate or cast-in-situ concrete cover plate on the pile top, to connect the cover plate with the raft plate via the planted bars or anchor bolts, and to solve the punching force between the steel pile and the raft plate via the punching resistance, bending resistance and pull-out resistance of the anchor bolts. Because this power is generally great, in order to satisfy die-cut requirement, the apron should have certain thickness, so often local arch influences the normal use in raft top surface space. And the apron links to each other with the raft through bar planting or crab-bolt, and its reliability is relatively poor.

The reserved taper hole method is used for partial enlargement of the raft, the taper hole is reserved in the cast-in-place section, after the construction of the steel pile is completed, non-shrinkage fine aggregate concrete is poured into the taper hole, and the bearing capacity of the concrete subjected to punching is utilized. According to the connection method, if the local ground is required to be prevented from being higher than the top surface of the raft, the result needs to be calculated according to the bearing capacity, and the raft is thickened downwards. This kind of connected mode atress is reliable relatively, but probably needs to destroy the former waterproof layer, if the ground water level is higher, still needs precipitation to handle, and has the disturbance to lower part foundation soil. The local breaking-in post-pouring method is similar to the reserved taper hole method, namely the local raft is removed, the post-pouring block is reserved, the concrete interfaces poured successively are subjected to roughening, bar planting and other treatments, the method is relatively reliable, and the defects that wet operation is more and the method is influenced by foundation soil and underground water below a foundation are still overcome.

Therefore, it is important to find a method for raising the bearing capacity of the raft plate by punching, without damaging the water-proof under the bottom plate and raising the height of the raft plate.

A structural steel shear frame is usually adopted in a newly-built plate column structure to improve the punched bearing capacity of a plate column node, but the structural steel shear frame is not applied in a modified structure; in the newly-built structure and the modified structure of the basic raft, the case that the bearing capacity of the raft is improved by punching by using the steel shear frame is not found.

SUMMERY OF THE UTILITY MODEL

Under the action of the rear steel pile, the thickness of the raft is often controlled by the punching bearing capacity of the raft, and the punching bearing capacity is mainly related to the concrete strength, the thickness of the concrete plate and the punching load acting area. After the profile steel shear frame is arranged, because the shear resistance of the profile steel is stronger, after the requirements of relevant structures are met, the punching damage conical surface is moved outwards, the punching damage surface is increased, and therefore the punching bearing capacity of the raft can be greatly improved.

The profile steel shear frame can be welded into a cross shape or a groined shape as required, and when the section of the steel pile is smaller, the cross shape can be adopted. After the steel pile is pressed in place, the top surface of the raft is grooved, and the depth of the groove ensures that the bottom flange of the section steel can be positioned at the bottom of the raft for 0.3h ₀ Within range, the width of groove is greater than the shaped steel width each side and respectively adds 50mm, after shaped steel installation targets in place, connects the board top reinforcing bar that cuts off, then pours the pea gravel concreten, when pouring, can pour into from shaped steel one side, and the concrete is gushed out from the opposite side, ensures that the shaped steel bottom pours closely knit. In order to improve the common working performance of the section steel and the concrete, studs can be welded on the upper surface and the lower surface of the section steel or on the surface of one side of the section steel. Is composed ofStress concentration of the section steel limb end on the concrete raft plate is avoided, and limbs can be cut from one side facing the top of the concrete raft plate. The layout of the section steel is schematically shown in FIG. 6.

Because the wall thickness of the steel pipe is smaller, the concrete is easy to be locally damaged when the steel pipe transmits force with the concrete. The device directly transmits force between the steel pipe pile and the profile steel shear frame, and stiffening ribs are welded on the corresponding wall parts of the steel pipes of the shear frame. The stiffening rib corner cut is favorable for concrete pouring.

When the thickness of the raft is insufficient, the thickness of the raft can be increased moderately.

When the steel pile is repaired later, because of the existence of a new and old concrete joint surface, the problems of water seepage and water leakage easily occur, and when the outer ring plate is adopted for stopping water, the phenomenon of incompact concrete pouring easily occurs on the outer side of the outer ring plate. For solving this problem, this device has reserved the preformed hole of installation back slip casting steel pipe on the outer crown plate, before concrete raft pours, installation slip casting steel pipe. And after the concrete reaches the designed strength, performing pressure grouting to ensure that the lower part of the annular plate is densely filled.

Description of the drawings:

in order to show the patent of the utility model more clearly, the corresponding attached drawings of each implementation stage are as follows:

fig. 1 is a schematic drawing of the opening of the existing raft, 1 is the raft, and 2 is the hole.

Fig. 2 is a schematic diagram of the steel pipe pile in place, 3 is the steel pipe pile, 7 is an upper ring plate of the steel pipe pile, and 8 is a grouting hole.

Fig. 3 is a cross-shaped groove formed in the middle upper part of the raft, and 4 is a groove.

Fig. 4 is a schematic view of the steel pipe pile after the steel bars and the concrete are poured, and 5 is a steel reinforcement framework.

FIG. 5 is a schematic view of a section steel shear frame.

FIG. 6 is a schematic view showing the installation of the section steel shear frame, which is a plan view, and FIG. 6 is a section steel shear frame.

Fig. 7 is a side view.

FIG. 8 is a sectional view of the section where the section steel shear frame is located.

The specific implementation mode is as follows:

the main construction sequence is as follows: the design of shaped steel shear frame, shaped steel shear frame preparation, raft trompil, static pressure steel pile, raft fluting, installation shaped steel, reinforcing bar are handled, pour fine aggregate concrete, pressure slip casting.

And determining the section, the length and the mounting position of the section steel shear frame according to calculation and construction requirements. And (5) manufacturing the profile steel shear frame. And (4) opening holes on the raft plates according to the sections of the steel piles. A pile pressing machine is adopted to press the steel pile into a preset depth, then a chiseling tool is adopted to pick out two crossed U-shaped grooves on a raft plate, the upper part of each U-shaped groove is wide and the lower part of each U-shaped groove is narrow, the bottom surface of each U-shaped groove is a plane, the width of each groove is larger than the width of the section steel by 100mm, and the depth of each groove is larger than the rigidity of the section steel by 100mm. And (5) mounting a profile steel shear frame. And welding and connecting the cut steel bars. And (5) pouring concrete. And curing the concrete to reach the strength, performing pressure grouting, and finishing construction.

The advantage of this device is under the condition of equal raft thickness, but furthest's improvement raft receives die-cut bearing capacity, and the concrete consumption is minimum, and is minimum to building function influence. The concrete in a certain height range at the bottom of the raft is not broken, namely, the original rigid waterproof section is reserved, the waterproof under the original raft is not damaged, and the original foundation soil is not disturbed. The construction quality is controllable.

Examples

The foundation is a piled raft foundation, a prestressed concrete pipe pile is prefabricated, the thickness of a raft plate is 500mm, and the strength grade of concrete is C30. The foundation soil below is silt with the thickness of 6 meters, and then silt, sand and completely weathered and strongly weathered sandstone are arranged below the foundation soil. Actually measuring the water level at the elevation of the bottom surface of the raft. Because the structure is reformed, need improve the vertical bearing capacity of basis, through comprehensive analysis, select at last to open a hole on the raft board, utilize the structure dead weight, adopt the static pressure mode, the back is mended the steel pile. The cross section of the steel pile is a round steel pipe with the outer diameter of 300mm, and the wall thickness of the round steel pipe is 8mm. The problem of die cutting by raft plate concrete needs to be increased in thickness. When the wall is thickened upwards, the indoor clear height is influenced; when thickening downwards, destroy former raft waterproof layer down, and ground water level is higher, needs the precipitation operation, excavates below silt, enlarges the broken area of tearing open of raft, and the construction degree of difficulty is great, and the cost is higher. In order to keep the thickness of the raft unchanged and improve the punched bearing capacity of the raft, anti-punching reinforcing steel bars can be configured and a profile steel shear frame can be arranged. When the configuration is anti die-cut reinforcing bar, receive die-cut reinforcing bar and need lead to the height along raft thickness direction and arrange, still need all demolish raft along thickness direction this moment. When the H200X 200 profile steel shear frame is adopted, the bottom of the raft can keep the thickness of 100mm without being detached, so that the problems can be avoided.

The method comprises the following steps: this project adopts to set up shaped steel shear frame in the raft and solves the die-cut problem of raft. The section of the profile steel shear frame is H200 multiplied by 200, and the length of the extending arm is 800mm.

Step two: and welding an upper ring plate with the thickness of 10mm and the width of 40mm on the rear steel-supplementing pile, and forming a grouting hole on the upper ring plate.

Step three: and (5) punching holes on the raft plates, wherein the diameter of each hole is 500mm, and filling steel piles after pressing.

Step four: the upper portion opens the cross recess in raft, and the recess length of every direction is 1700mm, and the recess section is for falling trapezoidal, the wide 300mm in bottom, the wide 600mm in top, and the recess degree of depth is 400mm, and the board top reinforcing bar cuts off, reserves 200mm wide interval.

Step five: and manufacturing a profile steel shear frame, welding H200X 200 profile steel into a cross shape, wherein the length of each direction is 1600mm. Placing the section steel shear frame into the groove, enabling the top surface of the upper flange of the shear frame to be 100mm away from the top surface of the raft plate, and connecting the upper flange and the raft plate to form a grouting pipe;

step six: adopting the same-diameter steel bars for lap welding for 10d, coating an interface agent on the concrete interface, and pouring fine aggregate concrete;

step seven: and (5) after the concrete reaches the strength, performing pressure grouting.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that may be made by those skilled in the art within the technical scope of the present invention will be covered by the scope of the present invention.

Claims (6)

1. The utility model provides an improve device that benefit steel pile raft board received die-cut bearing capacity after, it includes: the steel-pipe pile of outband ring plate, shaped steel shear frame, raft board, the cross recess that upper portion was seted up in the raft board, the recess cross section is for falling trapezoidal, falls trapezoidal recess bottom width and is greater than shaped steel bottom flange width to guarantee pouring of concrete, the recess height is greater than the shaped steel height, back slip casting steel pipe.

2. The device of claim 1, wherein the outer ring plate is welded on the top of the steel pipe pile, grouting holes are reserved in the outer ring plate, the grouting steel pipes are welded to the top surface of the raft, after the concrete reaches the strength, pressure grouting is performed in the grouting steel pipes, and the injected cement fills gaps below the outer ring plate of the steel pipe pile, so that the waterproof problem is solved.

3. A device according to claim 1, wherein a profiled steel shear frame is used to increase the die-cut load bearing capacity of the rafts.

4. A device according to any one of claims 1 and 3, wherein the thickness of the raft may be suitably thickened when the thickness of the raft is still not satisfied after taking into account the effect of the steel shear frame on the elevated die-cut bearing capacity.

5. An apparatus according to any one of claims 1 to 3, wherein the raft may be a cap.

6. The apparatus of claim 4, wherein the raft may be a cap.

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