A composite foundation structure of gravel piles at the base of roadbed and construction method thereof

Abstract

The present invention relates to the technical field of roadbed foundation piles, and in particular to a composite foundation structure of gravel piles for roadbed foundation and a construction method, comprising a foundation soil layer and a plurality of gravel piles arranged in the foundation soil layer, wherein a pile hole for accommodating the gravel piles is arranged in the foundation soil layer, each gravel pile comprises a casing for filling gravel, a steel cage is arranged in the casing, a grouting steel pipe is arranged in the steel cage, a plurality of grouting holes are arranged on the side wall of the grouting steel pipe, four moving rods are arranged in the grouting steel pipe, a plurality of supporting rods are arranged on the four moving rods, and each moving rod comprises an upper half and a lower half, a plurality of supporting rods arranged on two moving rods are located in the upper half of the moving rods, a plurality of supporting rods arranged on the other two moving rods are located in the lower half of the moving rods, a plurality of through holes corresponding to the supporting rods are arranged on the side wall of the grouting steel pipe, the moving rods push, and each supporting rod passes through the through hole and the steel cage. The present invention provides a composite foundation structure and a construction method to enhance the bearing capacity of the composite foundation.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed piles, and in particular to a roadbed base gravel pile composite foundation structure and a construction method. Background Art

[0002] Composite foundation refers to an artificial foundation in which the soil of a natural foundation is reinforced or replaced during the foundation treatment process. The reinforced area is composed of a base and a reinforcement. Under the action of load, the base and the reinforcement jointly bear the load. During the construction of composite foundation, gravel piles are generally used to reinforce the soft soil foundation.

[0003] In the existing technology, the gravel pile composite foundation structure generally includes a foundation soil layer and a plurality of gravel piles arranged in the foundation soil layer. First, holes are dug in the foundation soil layer to install the required gravel piles. The gravel pile is a pile body filled with gravel. During construction, a vibrating pile driver is first used to drive the casing into the pile hole, and gravel is put into the pipe. The gravel is then pressed into the soil, and the pipe is gradually pulled out. The gravel is vibrated and compacted in sections to form a gravel pile, and the soil between the piles is squeezed and compacted. A layer of gravel cushion is laid on the top of the gravel pile, so that the soil between the gravel pile and the original soil layer forms a composite foundation that jointly bears the load of the upper building structure.

[0004] The above-mentioned prior art solutions have the following defects: since the gravel pile is a bulk material pile, mainly, the structure of the gravel pile installed on the foundation soil layer is relatively simple, and only relies on the strength of the pile body itself and the constraint of the surrounding soil to resist the vertical load transmitted from the foundation, so that the constraint force between the pile body and the surrounding soil is not strong. The softer the soil layer around the pile body, the poorer the constraint force on the gravel pile, making the pile body easy to deform and loose, thereby making the bearing capacity of the composite foundation lower. Summary of the invention

[0005] In view of the shortcomings of the prior art, one of the purposes of the present invention is to provide a composite foundation structure of gravel piles at the base of a roadbed, which has the advantage of improving the bearing capacity.

[0006] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0007] A composite foundation structure of gravel piles at the base of a roadbed, comprising a foundation soil layer and a plurality of gravel piles arranged in the foundation soil layer, wherein a pile hole for accommodating the gravel piles is arranged in the foundation soil layer, each of the gravel piles comprises a casing for filling gravel fillers to form a pile body, a steel cage is arranged in the casing, the steel cage is arranged coaxially with the pile hole, a grouting steel pipe is arranged in the steel cage, a plurality of grouting holes for pouring concrete slurry are arranged on the side wall of the grouting steel pipe, four moving rods are arranged in the grouting steel pipe, the four moving rods are arranged along the length direction of the grouting steel pipe, and the four moving rods are arranged There are multiple support rods, which are arranged along the length direction of the corresponding moving rods, and each moving rod includes an upper half and a lower half. The multiple support rods arranged on two of the moving rods are located in the upper half of the moving rods, and the multiple support rods arranged on the other two moving rods are located in the lower half of the moving rods. The side wall of the grouting steel pipe is provided with multiple through holes corresponding to the support rods. The moving rod pushes each of the support rods to pass through the through holes and the steel cage extends out of the steel cage. A fixing component for fixing the moving rod is arranged between the grouting steel pipe and each of the moving rods.

[0008] By adopting the above technical scheme, a steel cage is added in the casing, and a grouting steel pipe is added in the steel cage. A plurality of support rods extending out of the grouting steel pipe and the steel cage are added in the grouting steel pipe, so that the supporting strength of the gravel pile can be enhanced and the deformation of the gravel pile can be reduced. A grouting hole is opened on the side wall of the grouting steel pipe, and concrete slurry is poured into the grouting hole, so that the concrete slurry flows out from the casing and the steel cage through the grouting hole, thereby reducing the gap between the gravel fillers and enhancing the bonding force between the gravel fillers. The gravel pile and the base soil layer form a composite foundation, thereby enhancing the bearing capacity of the composite foundation. In addition, at the two moving rods The support rod is set in the upper half of the moving rod, and the support rods of the two moving rods are set in the lower half of the moving rod. During construction, the two moving rods are first pushed to make the support rods set in the lower half of the moving rod extend out of the grouting steel pipe and the steel cage. After filling a part of the gravel filler and tamping and vibrating the part of the gravel filler, the other two moving rods are pushed to make the support rods set in the upper half of the moving rod extend out of the grouting steel pipe and the steel cage, and the gravel filler is put in again and tamped and vibrated. In this way, the gravel filler can be tamped evenly by tamping in sections, thereby reducing the loosening of the gravel filler, thereby reinforcing the gravel pile foundation.

[0009] In a preferred example, the present invention can be further configured as follows: a guide assembly is provided between each of the moving rods and the grouting steel pipe, the guide assembly includes a guide ring and a guide rod, the guide rod is on the grouting steel pipe, the guide ring is connected to one end of the moving rod close to the bottom of the pile hole, the guide ring is sleeved on the guide rod and slidingly cooperates with the guide rod.

[0010] By adopting the above technical solution, the sliding cooperation between the guide rod and the guide ring guides the moving rod, making it difficult for the moving rod to deviate during the movement, thereby enabling the support rod to be better pushed out of the grouting steel pipe and the steel cage.

[0011] In a preferred example, the present invention can be further configured as follows: a plurality of limit ridges are arranged on the inner side of the steel cage, and a plurality of the limit ridges are arranged along the length direction of the steel bar hole; a guide ridge is arranged on the outer wall of the grouting steel pipe; a limit groove corresponding to each limit ridge is arranged on the surface of the guide ridge facing away from the grouting steel pipe; and the limit groove is arranged from one end of the grouting steel pipe inserted into the steel cage along the length direction of the guide ridge, and the limit ridge is slidably matched with the corresponding limit groove.

[0012] By adopting the above technical solution, the limiting convex strip and the limiting groove slide together to play a limiting role, so that the grouting steel pipe is not easy to rotate when placed in the steel cage, which is convenient for construction workers to place the grouting steel pipe into the steel cage.

[0013] In a preferred example, the present invention can be further configured as follows: a positioning ring is connected to the top of each grouting steel pipe, a connecting pipe is connected between two adjacent positioning rings, the connecting pipe is hollow, and both ends of the connecting pipe are closed ends, a plurality of fixing holes corresponding to the connecting pipe are provided between two adjacent positioning rings, both ends of the connecting pipe respectively pass through the fixing holes corresponding to the two adjacent positioning rings and extend into the positioning rings, and abutment components for fixing the connecting pipe in the positioning rings are provided between both ends of the connecting pipe and the positioning plate.

[0014] By adopting the above technical solution, the setting of the connecting pipe can enhance the connection force between two adjacent gravel piles, so that the pile bodies of each gravel pile are connected as a whole, thereby reinforcing the foundation as a whole and reducing the occurrence of uneven force and tilt of the gravel piles.

[0015] In a preferred example, the present invention can be further configured as follows: the abutment assembly includes two support blocks, the two support blocks are respectively located at the two ends of the connecting tube along the diameter direction, the side wall of the connecting tube is provided with a connecting hole for each support block to extend out of the connecting tube, and the connecting tube is provided with two push rods for pushing the support blocks on both sides of the connecting tube to extend out of the connecting tube, and the two push rods move away from each other in the connecting tube, and an elastic member is connected between the two push rods. When the elastic member is in a natural state, each support block extends out of the corresponding connecting hole and is in abutment with the inner wall of the positioning ring.

[0016] By adopting the above technical solution, the setting of the support block can limit the two ends of the connecting tube within the positioning ring, making it difficult for the connecting tube to detach from the positioning ring. A push rod is added to facilitate pushing the support block out of the connecting tube. Since the elastic member has elastic restoring force, the push rod is not easy to slide in the connecting tube, and the support block is not easy to fall into the connecting tube.

[0017] In a preferred example, the present invention can be further configured as follows: a shift block is provided on each of the push rods, a through groove corresponding to the shift block is provided on the side wall of the connecting tube, the through groove is provided along the length direction of the connecting tube, the shift block passes through the through groove and extends out of the connecting tube, the shift block is slidably connected to the through groove, and when the shift block abuts against a groove wall of the through groove away from the supporting block, a fastening piece for fastening the two shift blocks is provided between the two shift blocks.

[0018] By adopting the above technical solution, the setting of the shifting block can facilitate the pushing rod, and a snap-fitting part is added at the same time. When there is no need to push the support block out of the connecting tube, the pushing rod can be fixed in the connecting tube and is not easy to move, which is also convenient for carrying the connecting tube. When the support block needs to be extended out of the connecting tube, it is only necessary to remove the snap-fitting part and move the push rod to make the support block extend out of the connecting tube.

[0019] In a preferred example, the present invention can be further configured as follows: anchor rods are provided on both sides of the connecting pipe, each of the push rods is provided with a first through hole, and the side wall of the connecting pipe is provided with a second through hole that is arranged through the through hole. When the elastic member is in a natural state, the anchor rods are sequentially passed through the first through hole and the second through hole and anchored to the foundation soil layer.

[0020] By adopting the above technical solution, the anchor rod passes through the first through hole and the second through hole in sequence and is anchored in the foundation soil layer, which supports the connecting pipe and enhances the stability of the connecting pipe in the foundation soil layer.

[0021] In a preferred example, the present invention may be further configured as follows: one end of each of the support blocks located in the connecting tube is connected to an abutment block for limiting the position of the support block.

[0022] By adopting the above technical solution, the setting of the abutment block plays a limiting role on the support block, so that the support block is not easy to fall from the connecting pipe when it is pushed out of the connecting pipe by the push rod.

[0023] In a preferred example, the present invention can be further configured as follows: the inner side wall of the sleeve is circumferentially provided with a steel mesh.

[0024] By adopting the above technical solution, the provision of the steel mesh can limit the gravel filler in the gravel pile from entering the surrounding soil, avoid the diffusion and lateral expansion of the gravel filler in the gravel pile, and reduce the deformation of the gravel pile.

[0025] The second object of the present invention is to provide a method for constructing a composite foundation of gravel piles at the base of a roadbed, which is suitable for soft foundations to improve the bearing capacity of the composite foundation.

[0026] The above-mentioned object of the present invention is achieved through the following technical solutions:

[0027] A method for constructing a composite foundation of gravel piles at the base of a roadbed comprises the following steps:

[0028] S1. Clean the ground, flatten and compact it, place piles within the construction scope, and make construction technical instructions (including pile length, pile position layout, etc.), dig the required depth of gravel piles at the pile positions to form pile holes, transport the abandoned soil to the designated location with a bucket truck, and select non-weathered gravel, debris and stone chips according to the required requirements to form gravel filler according to the mix ratio;

[0029] S2. Put the ZCQ55 vibrating pile driver in place, align the casing with the pile hole, start the vibrating pile driver to drive the casing into the pile hole, and use the crane to hang the steel mesh into the casing, fix the steel cage in the casing and set it coaxially with the casing, and put the grouting steel pipe into the steel cage;

[0030] S3, push the two moving rods to move away from each other, so that the support rods welded to the lower half of the two moving rods extend out of the grouting steel pipe and the steel cage, fix the two moving rods relative to each other, fill the space between the casing and the steel cage with the crushed stone filler matched in S1, make the pile height of the crushed stone filler higher than the height between the support rod farthest from the bottom of the pile hole and the bottom of the pile hole, vibrate the casing with a vibrating pile driver, gradually pull out the pipe while vibrating, control the pulling speed within the range of 0.8-1.0 m / min, use a rammer and lift it to a certain height (generally more than 2.0 m), let it fall freely to impact the ingredients poured into the casing, and tamp it several times to compact and vibrate the crushed stone filler;

[0031] S4, push the other two opposite moving rods to make them move away from each other, the support rods welded on the upper half of the two moving rods extend out of the grouting steel pipe and the steel cage, fix the other two opposite moving rods, fill the space between the casing and the steel cage with gravel filler again, vibrate the casing with a vibrating pile driver, gradually pull out the casing, use a rammer to compact the gravel filler, and squeeze the steel mesh and the soil around the pile hole to make it dense;

[0032] S6, pouring concrete slurry into the grouting steel pipe, so that the concrete slurry flows out through the slurry outlet holes to the space between the steel cage and the steel mesh, and waiting for the concrete slurry to solidify to form a gravel pile;

[0033] S7. After the gravel piles in S6 have passed the inspection, a positioning ring set on the grouting steel pipe is fixedly sleeved on the top of the grouting steel pipe, and two adjacent positioning rings fixed on the steel cage are connected by a connecting pipe. The buckle is unlocked, and the push rod installed in the connecting pipe pushes the support block, so that the support block moves outward and contacts the positioning ring. The anchor rod is passed through the push rod and the connecting pipe and anchored to the ground, so that multiple gravel piles are connected into one, and a layer of gravel filler is laid on the top of the gravel pile to form a 20 cm gravel cushion layer and compacted to form the required gravel pile composite foundation.

[0034] In summary, the present invention includes at least one of the following beneficial technical effects:

[0035] 1. Add a steel cage inside the casing, and add a grouting steel pipe inside the steel cage. Add multiple support rods extending out of the grouting steel pipe and the steel cage inside the grouting steel pipe. Open a grouting hole on the side wall of the grouting steel pipe, and pour concrete slurry into the grouting hole, so that the concrete slurry flows out from the casing and the steel cage through the grouting hole, thereby reducing the gap between the crushed stone fillers and enhancing the bonding force between the crushed stone fillers, so as to enhance the bearing capacity of the crushed stone pile foundation;

[0036] 2. The limiting convex strip and the limiting groove slide together to play a limiting role, so that the grouting steel pipe is not easy to rotate when it is placed in the steel cage, which is convenient for construction workers to put the grouting steel pipe into the steel cage;

[0037] 3. The setting of the connecting pipe can enhance the connection force between two adjacent gravel piles, thereby reinforcing the foundation;

[0038] 4. The anchor rods sequentially penetrate the first through hole and the second through hole and are anchored in the foundation soil layer, which supports the connecting pipe and enhances the stability of the connecting pipe in the foundation soil layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the composite foundation of the present invention;

[0040] Figure 2 It is a schematic structural diagram of a single gravel pile of the present invention;

[0041] Figure 3 It is a structural schematic diagram of the grouting steel pipe of the present invention;

[0042] Figure 4 The present invention Figure 3 A magnified view of part A;

[0043] Figure 5 The present invention Figure 3 Enlarged view of part B

[0044] Figure 6 It is a partial structural schematic diagram of the steel cage of the present invention;

[0045] Figure 7 It is a schematic structural diagram of the connecting pipe of the present invention after being cut open.

[0046] In the figure, 1, foundation soil layer; 2, pile hole; 3, casing; 4, steel mesh; 5, crushed stone filler; 6, steel cage; 61, steel ring; 62, steel vertical rod; 7, barb; 8, grouting steel pipe; 9, slurry outlet hole; 10, limiting convex strip; 11, guide convex strip; 12, limiting groove; 13, support rod; 14, moving rod; 15, guide rod; 16, guide ring; 17, positioning ring; 18, positioning plate; 19, first bolt; 20, through hole; 21, connecting pipe; 22, fixing hole; 23, supporting block; 24, abutting block; 25, push rod; 26, spring; 27, shifting block; 28, through groove; 29, anchor rod; 30, first through hole; 31, second through hole; 32, second bolt; 33, connecting hole; 34, grouting groove; 35, barb tip; 36, installation hole. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0048] Reference Figure 1 and Figure 2 , a composite foundation structure of gravel piles for roadbed base and a construction method disclosed by the present invention, including a foundation soil layer 1 and a plurality of gravel piles arranged in the foundation soil layer 1, each gravel pile includes a casing 3 for filling gravel filler 5 to form a pile body. First, a pile hole 2 of a required depth is dug in the foundation soil layer 1, and when the casing 3 is driven into the pile hole 2, a steel mesh 4 is placed circumferentially on the inner wall of the casing 3 to reduce the displacement and deformation of the gravel pile, and the gravel filler 5 is filled, and the pipe is gradually pulled out, and it is compacted multiple times with a rammer, and repeatedly vibrated to form a gravel pile. A layer of gravel filler 5 is laid on the top of the gravel pile to form a 20 cm gravel cushion layer, so that the gravel pile, the reinforced foundation soil and the gravel cushion layer form a composite foundation.

[0049] In order to enhance the bearing strength of the gravel pile composite foundation, a steel cage 6 is placed in the above-mentioned casing 3. The diameter of the steel cage 6 is smaller than that of the casing 3, and the steel cage 6 is arranged along the length direction of the casing 3. The steel cage 6 is coaxially arranged with the casing 3. In this embodiment, the steel cage 6 is composed of a plurality of steel rings 61 and a plurality of steel vertical rods 62. The plurality of steel rings 61 are arranged along the length direction of the casing 3. The plurality of steel vertical rods 62 are welded to each steel ring 61 in sequence along the distribution direction of the plurality of steel rings 61, and the plurality of steel vertical rods 62 are welded and fixed at equal distances along the circumferential direction of the steel rings 61. In addition, a plurality of barbs 7 are arranged at the bottom of the steel cage 6. The plurality of barbs 7 are arranged circumferentially along the steel rings 61 that are in contact with the bottom of the pile hole 2, and the plurality of barbs 7 are inserted into the soil at the bottom of the pile hole 2, thereby enhancing the ground grip strength of the steel cage 6, so that the steel cage 6 is fixed in the casing 3.

[0050] Reference Figure 3 and Figure 4 At the same time, a grouting steel pipe 8 is installed in the steel cage 6. The grouting steel pipe 8 is arranged along the length direction of the steel cage 6, and a grouting groove 34 is opened on the grouting steel pipe 8. The grouting groove 34 is arranged along the length direction of the grouting steel pipe 8 from the end of the grouting steel pipe 8 away from the bottom of the pile hole 2. A plurality of grouting holes 9 are opened in the circumferential direction of the side wall of the grouting steel pipe 8, and the grouting holes 9 are used to pour concrete slurry. The plurality of grouting holes 9 form four rows, and the grouting holes 9 in each row are arranged along the length direction of the grouting steel pipe 8. A plurality of limiting convex strips 10 are welded circumferentially on the inner side of each steel ring 61 in the steel cage 6. In this embodiment, the number of limiting convex strips 10 is four. Correspondingly, the outer wall of the grouting steel pipe 8 is welded with a guide convex strip 11 corresponding to the limiting convex strip 10 welded on each steel ring 61. Each guide convex strip 11 is respectively located between two adjacent grouting holes 9, and the guide convex strip 11 is arranged along the length direction of the grouting steel pipe 8. A limiting groove 12 is provided on the surface of the side of the guide convex strip 11 away from the grouting steel pipe 8, and the limiting groove 12 is arranged along the length direction of the guide convex strip 11, and the limiting convex strip 10 is slidably matched with the corresponding limiting groove 12 to limit the grouting steel pipe 8, so that the grouting steel pipe 8 is not easy to deviate when placed in the steel cage 6. In addition, a plurality of conical spikes 35 are circumferentially welded to one end of the grouting steel pipe 8 near the bottom of the pile hole 2, and the spikes 35 are inserted into the soil at the bottom of the pile hole 2 to enhance the gripping ability of the grouting steel pipe 8 and fix the grouting steel pipe 8 to the bottom of the pile hole 2.

[0051] Reference Figure 2 and Figure 3A plurality of moving rods 14 are arranged in the grouting steel pipe 8, and the number of the moving rods 14 is four. The four moving rods 14 are arranged along the length direction of the grouting steel pipe 8, and one end of the moving rod 14 extends out of the grouting steel pipe 8. A plurality of supporting rods 13 are welded to the side wall of the moving rod 14, and the plurality of supporting rods 13 are arranged along the length direction of the moving rod 14. Each moving rod 14 includes an upper half and a lower half. The plurality of supporting rods 13 welded to two opposite moving rods 14 are located in the upper half of the corresponding moving rod 14, and the supporting rods 13 welded to the other two opposite moving rods 14 are located in the lower half of the corresponding moving rod 14. The side wall of the grouting steel pipe 8 is provided with through holes 20 in the circumferential direction for the supporting rods 13 to extend out of the grouting steel pipe 8 and the steel cage 6, and the through holes 20 are arranged to penetrate. The support rod 13 extends out of the grouting steel pipe 8 and the steel cage 6 through the through hole 20, and one end of each support rod 13 away from the moving rod 14 contacts the inner side of the steel mesh 4, thereby enhancing the support strength of the gravel pile and reducing the deformation of the gravel pile. It is worth mentioning that there is a space on the steel cage 6 for each support rod 13 to extend out of the steel cage 6. In addition, in order to prevent the support rod 13 from being easily offset during the pushing process, a guide assembly for guiding the moving rod 14 is provided between the grouting steel pipe 8 and each moving rod 14, and the guide assembly includes a guide ring 16 and a guide rod 15. The guide rod 15 and the guide ring 16 are both located at one end of the grouting steel pipe 8 close to the bottom of the grouting groove 34, and the guide ring 16 is welded to one end of the moving rod 14 close to the bottom of the grouting groove 34, one end of the guide rod 15 in each group of guide assemblies is welded and fixed to the inner side wall of the grouting steel pipe 8, and the other ends of the guide rods 15 in each group of guide assemblies are welded and fixed to each other, and each guide ring 16 is sleeved on the corresponding guide rod 15 for sliding fit. During construction, a crane can be used to lift the hydraulic cylinder into the grouting steel pipe 8, thereby pushing the moving rod 14 to move, and the guide ring 16 and the guide rod 15 slide and cooperate, so as to guide the moving rod 14 and prevent the moving rod 14 from deviating and moving.

[0052] Reference Figure 3 and Figure 5Two positioning plates 18 are arranged on the top of the grouting steel pipe 8. Both sides of the two positioning plates 18 are provided with mounting holes for the moving rods 14 to pass through. Fasteners for fixing the positioning plates 18 are arranged between both sides of the two positioning plates 18 and the grouting steel pipe 8. In this embodiment, the fasteners are first bolts 19. When the support rods 13 located at the lower half of the two opposite moving rods 14 are pushed out of the grouting steel pipe 8 and the steel cage 6, one positioning plate 18 is sleeved on the two opposite moving rods 14 through the mounting holes, and the surface of one side of the positioning plate 18 facing the grouting groove 34 is against the top of the grouting steel pipe 8. The first bolt 19 penetrates the positioning plate 18 and is threadedly connected to the top of the grouting steel pipe 8. The crushed stone filler 5 can be filled into the space between the casing 3 and the steel cage 6, and the crushed stone filler 5 is compacted by a rammer. When the support rod 13 located at the upper half of the two opposite moving rods 14 is pushed out of the grouting steel pipe 8 and the steel cage 6, another positioning plate 18 is sleeved on the other two opposite moving rods 14 through the mounting hole 36, and the other positioning plate 18 abuts against the surface of one positioning plate 18 on the side away from the grouting groove 34. At this time, the first bolt 19 threadably connects the other positioning plate 18 with the grouting steel pipe 8. The crushed stone filler 5 is put in again and compacted by tamping, and concrete slurry is poured into the grouting steel pipe 8. After the concrete slurry is formed and solidified, the required crushed stone pile is formed.

[0053] Reference Figure 1 and Figure 2 In order to enhance the overall strength of the gravel pile composite foundation and enable the connection between two adjacent gravel piles to be more stable, a positioning ring 17 is sleeved on the top of each grouting steel pipe 8, and a plurality of second bolts 32 are arranged circumferentially on the positioning ring 17. The plurality of second bolts 32 penetrate the positioning ring 17 and are threadedly connected to the outer wall of the grouting steel pipe 8. A connecting pipe 21 is connected between two adjacent positioning rings 17, and a fixing hole 22 is provided between two adjacent positioning rings 17. Both ends of the connecting pipe 21 pass through the fixing holes 22 corresponding to the two adjacent positioning rings 17 and extend into the positioning rings 17. At this time, every three connecting pipes 21 can form an equilateral triangle, thereby connecting and reinforcing two adjacent gravel piles.

[0054] Reference Figure 7In order to fix the connecting tube 21 in two adjacent positioning rings 17 and prevent it from loosening, the connecting tube 21 is horizontally arranged and hollow, and both ends of the connecting tube 21 are closed ends. Two support blocks 23 are arranged on both sides of the connecting tube 21 extending into the corresponding positioning ring 17. The two support blocks 23 are both located in the connecting tube 21 and are respectively located at both ends of the diameter direction of the connecting tube 21. At the same time, the side wall of the connecting tube 21 is provided with a connecting hole 33 for each support block 23 to extend out of the connecting tube 21. Two push rods 25 are arranged in the connecting tube 21 for pushing the support blocks 23 on both sides of the connecting tube 21 to extend out of the connecting tube 21. The two push rods 25 move away from each other in the connecting tube 21, and each support block 23 extends out of the connecting hole 33, and the side surface of the support block 23 close to the positioning ring 17 is in contact with the inner side wall of the positioning ring 17. In addition, to prevent the support block 23 from falling off from the connection hole 33, an abutment block 24 for limiting the position of the support block 23 is welded to one end of each support block 23 located in the connection tube 21. To facilitate the push rod 25 to push and abut the support block 23, a tip in a conical shape is provided at one end of the push rod 25 close to the support block 23, and a guide surface with the same inclination as the tip is provided at one end of each abutment block 24 close to the support block 23.

[0055] Reference Figure 7 , an elastic member is connected between the two opposite ends of the two push rods 25. In this embodiment, the elastic member is a spring 26, and the two ends of the spring 26 are fixedly connected to the opposite two side surfaces of the two push rods 25. A shift block 27 is welded to one side wall of each push rod 25, and a through slot 28 corresponding to each shift block 27 is provided on the side wall of the connecting pipe 21, and each through slot 28 is arranged along the length direction of the connecting pipe 21. The shift block 27 passes through the through slot 28 and extends out of the connecting pipe 21. The shift block 27 is slidably connected with the through slot 28. A fastening member for fixing the shift block 27 is arranged between the two shift blocks 27. The fastening member is an elastic buckle (not shown in the figure) arranged in a U shape. When the two shift blocks 27 abut against a groove wall of the through slot 28 away from the support block 23, the elastic buckle is fastened with the two shift blocks 27, thereby fastening and fixing the two shift blocks 27, and the support block 23 can be retracted into the connecting pipe 21, which is convenient for construction personnel. When it is necessary to extend the support block 23 out of the connecting tube 21, it is only necessary to remove the elastic buckle, and the two push rods 25 will automatically move under the action of the spring 26. When the tip of the push rod 25 hits the closed end of the connecting tube 21, the push rod 25 stops moving, and the spring 26 is in a natural state. At this time, the support block 23 extends out of the connecting tube 21.

[0056] Reference Figure 1 and Figure 7In addition, anchor rods 29 are provided on both sides of the connecting pipe 21, and each push rod 25 is provided with a first through hole 30 that is penetrated, and a second through hole 31 that is penetrated is provided on the side wall of the connecting pipe 21. When the elastic member is in a natural state, the push rod 25 is pushed by the spring 26, and the support block 23 extends outward. At this time, the first through hole 30 is aligned with the second through hole 31, and the anchor rod 29 is aligned with the first through hole 30 and the second through hole 31 in turn and anchored on the foundation soil layer 1, so that the connecting pipe 21 is further fixed in the two adjacent positioning rings 17, thereby enhancing the overall connection force of the gravel pile composite foundation.

[0057] A method for constructing a composite foundation of gravel piles at the base of a roadbed comprises the following steps:

[0058] S1. Prepare several vibrating pile drivers and bucket trucks, clean the ground, use bulldozers to push away surface weeds, rotten soil or planting soil, remove tree roots, grass roots and other debris, and flatten and compact the ground. Place pile positions within the construction scope, and make construction technical instructions (including pile length, pile position layout, etc.), dig the required depth of gravel piles at the pile positions to form pile holes 2, transport the abandoned soil to the designated location with bucket trucks, and select non-weathered gravel, debris and stone chips according to the required requirements and form the filler according to the mix ratio;

[0059] S2, ZCQ55 vibrating pile driver is in place, the casing 3 is aligned with the pile hole 2, the vibrating pile driver is turned on to drive the casing 3 into the pile hole 2, and the steel mesh 4 is hoisted into the casing 3 by a crane, the steel cage 6 is fixed in the casing 3 and coaxially arranged with the casing 3, and the grouting steel pipe 8 is placed in the steel cage 6;

[0060] S3, push the two moving rods 14 to move the two moving rods 14 away from each other, so that the support rods 13 welded to the lower half of the two moving rods 14 extend out of the grouting steel pipe 8 and the steel cage 6, and the positioning plate 18 is set on the two moving rods 14 through the mounting hole 36, and the positioning plate 18 is fixed to the top of the grouting steel pipe 8 by the first bolt 19, and the space between the casing 3 and the steel cage 6 is filled with the matched ingredients in S1, so that the stacking height of the ingredients is higher than the height of the support rod 13 farthest from the bottom of the pile hole 2 and the bottom of the pile hole 2 at this time, and the casing 3 is vibrated by a vibrating pile driver, and the pipe is gradually pulled out while vibrating, and the pulling speed is controlled within the range of 0.8-1.0 m / min, and a rammer is used and lifted to a certain height (generally more than 2.0 m), and the crushed stone filler 5 poured in the casing 3 is impacted by free fall, and the ramming is repeated for many times to compact and vibrate the ingredients;

[0061] S4, push the other two opposite moving rods 14 to make the other two opposite moving rods 14 move away from each other, the support rods 13 welded to the upper half of the two moving rods 14 extend out of the grouting steel pipe 8 and the steel cage 6, another positioning plate 18 is set on the other two opposite moving rods 14 through the installation hole, and the other positioning plate 18 is fixed with the second bolt 32, and the space between the casing 3 and the steel cage 6 is filled with gravel filler 5 again, the vibrating pile driver vibrates the casing 3, and the pipe is gradually pulled out, and the gravel filler 5 is compacted with a rammer, and the steel mesh 4 and the soil around the pile hole 2 are squeezed and compacted;

[0062] S6, pouring concrete slurry into the grouting steel pipe 8, so that the concrete slurry flows out through the slurry outlet hole 9 to the space between the steel cage 6 and the steel mesh 4, and waits for the concrete slurry to solidify to form a gravel pile;

[0063] S7. After the gravel piles in S6 have passed the inspection, the second bolt 32 is used to fix the positioning ring 17 sleeved on the grouting steel pipe 8 on the top of the grouting steel pipe 8, and the connecting pipe 21 is used to connect the two adjacent positioning rings 17 fixed on the steel cage 6, and the elastic buckle set on the connecting pipe 21 is unlocked, so that the push rod 25 installed in the connecting pipe 21 pushes the support block 23, so that the support block 23 moves outward and contacts the positioning ring 17, and the anchor rod 29 is passed through the push rod 25 and the connecting pipe 21 and anchored to the ground, so that multiple gravel piles are connected into one, and a layer of gravel is laid on the top of the gravel pile to form a 20 cm gravel cushion layer to form the required gravel pile composite foundation.

[0064] The implementation principle of this embodiment is as follows: a steel cage 6 is added inside the casing 3 to enhance the bearing capacity of the gravel pile, and a grouting steel pipe 8 is added inside the steel cage 6, and the moving rod 14 is pushed to make the support rod 13 extend out of the grouting steel pipe 8 and the steel cage 6 to increase the supporting strength between the casing 3 and the steel cage 6, and a grouting hole 9 is opened on the side wall of the grouting steel pipe 8, and concrete slurry is poured into the grouting hole 9, so that the concrete slurry flows out through the grouting hole 9 to the space between the casing 3 and the steel cage 6 to reduce the gap of the gravel filler 5, and at the same time, the connecting pipe 21 is connected between the positioning rings 17 between two adjacent gravel piles, which can reduce the settlement and deformation of the gravel pile, thereby reinforcing the gravel pile foundation to enhance the bearing capacity of the gravel pile composite foundation.

[0065] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A roadbed gravel pile composite foundation structure, comprising a foundation soil layer (1) and a plurality of gravel piles arranged in the foundation soil layer (1), Features: A pile hole (2) for accommodating the gravel pile is provided in the foundation soil layer (1), each of the gravel piles comprises a casing (3) for filling gravel filler (5) to form a pile body, a steel cage (6) is provided in the casing (3), the steel cage (6) is coaxially arranged with the pile hole (2), a grouting steel pipe (8) is provided in the steel cage (6), a plurality of grouting holes (9) for pouring concrete slurry are provided on the side wall of the grouting steel pipe (8), four moving rods (14) are provided in the grouting steel pipe (8), the four moving rods (14) are arranged along the length direction of the grouting steel pipe (8), and the four moving rods (14) are provided with a plurality of supporting rods (13), A plurality of support rods (13) are arranged along the length direction of the corresponding moving rod (14), and each moving rod (14) includes an upper half and a lower half. The plurality of support rods (13) arranged on two moving rods (14) are located in the upper half of the moving rod (14), and the plurality of support rods (13) arranged on the other two moving rods (14) are located in the lower half of the moving rod (14). The side wall of the grouting steel pipe (8) is provided with a plurality of through holes (20) corresponding to the support rods (13). The moving rod (14) pushes, and each of the support rods (13) passes through the through holes (20) and the steel cage (6) extends out of the steel cage (6); A guide assembly is provided between each of the moving rods (14) and the grouting steel pipe (8), the guide assembly comprising a guide ring (16) and a guide rod (15), the guide rod (15) being on the grouting steel pipe (8), the guide ring (16) being connected to one end of the moving rod (14) close to the bottom of the pile hole (2), the guide ring (16) being sleeved on the guide rod (15) and slidingly matched with the guide rod (15); A steel mesh (4) is circumferentially arranged on the inner side wall of the sleeve (3); A plurality of limiting convex strips (10) are arranged on the inner side of the steel cage (6), and a plurality of the limiting convex strips (10) are arranged along the length direction of the steel cage (6). A guide convex strip (11) is arranged on the outer wall of the grouting steel pipe (8). A limiting groove (12) corresponding to each limiting convex strip (10) is arranged on the side surface of the guide convex strip (11) away from the grouting steel pipe (8), and the limiting groove (12) is arranged to penetrate from one end of the grouting steel pipe (8) inserted into the steel cage (6) along the length direction of the guide convex strip (11), and the limiting convex strip (10) is slidably matched with the corresponding limiting groove (12).

2. A roadbed base gravel pile composite foundation structure according to claim 1, Features: A positioning ring (17) is connected to the top of each grouting steel pipe (8), and a connecting pipe (21) is connected between two adjacent positioning rings (17). The connecting pipe (21) is hollow and both ends of the connecting pipe (21) are closed ends. A plurality of fixing holes (22) corresponding to the connecting pipe (21) are provided between two adjacent positioning rings (17). Both ends of the connecting pipe (21) pass through the fixing holes (22) corresponding to the two adjacent positioning rings (17) and extend into the positioning ring (17). Abutment components for fixing the connecting pipe (21) in the positioning ring (17) are provided between both ends of the connecting pipe (21) and the positioning ring (17).

3. A roadbed base gravel pile composite foundation structure according to claim 2, Features: The abutment assembly comprises two support blocks (23), the two support blocks (23) are respectively located at two ends of the connecting tube (21) along the diameter direction, the side wall of the connecting tube (21) is provided with a connection hole (33) for each support block (23) to extend out of the connecting tube (21), and two push rods (25) are provided in the connecting tube (21) for pushing the support blocks (23) on both sides of the connecting tube (21) to extend out of the connecting tube (21), and the two push rods (25) move away from each other in the connecting tube (21), and an elastic member is connected between the two push rods (25), and when the elastic member is in a natural state, each support block (23) extends out of the corresponding connection hole (33) and is abutted against the inner wall of the positioning ring (17).

4. A roadbed base gravel pile composite foundation structure according to claim 3, Features: Each of the push rods (25) is provided with a shift block (27), and the side wall of the connecting tube (21) is provided with a through groove (28) corresponding to the shift block (27). The through groove (28) is arranged along the length direction of the connecting tube (21). The shift block (27) passes through the through groove (28) and extends out of the connecting tube (21). The shift block (27) is slidably connected to the through groove (28). When the shift block (27) contacts a groove wall of the through groove (28) away from the supporting block (23), a fastening member for fastening the two shift blocks (27) is arranged between the two shift blocks (27).

5. A roadbed base gravel pile composite foundation structure according to claim 3, Features: Anchor rods (29) are provided on both sides of the connecting tube (21), each of the push rods (25) is provided with a first through hole (30), and a second through hole (31) is provided on the side wall of the connecting tube (21). When the elastic member is in a natural state, the anchor rod (29) is sequentially inserted into the first through hole (30) and the second through hole (31) and anchored on the foundation soil layer (1).

6. A roadbed base gravel pile composite foundation structure according to claim 3, Features: One end of each support block (23) located in the connecting pipe (21) is connected to an abutment block (24) for limiting the position of the support block (23).

7. A construction method for a composite foundation structure of gravel piles at the roadbed base according to any one of claims 1 to 6, Features: The construction steps include: S1, cleaning the ground, leveling and compacting the ground, placing pile positions within the construction scope, and making construction technical instructions, digging the required depth of the gravel pile at the pile position to form the pile hole (2), transporting the abandoned soil to the designated location by a bucket truck, and selecting non-weathered gravel, debris and stone chips according to the required requirements to form the gravel filler in a mix ratio (5); S2, a ZCQ55 vibrating pile driver is in place, the casing (3) is aligned with the pile hole (2), the vibrating pile driver is turned on to drive the casing (3) into the pile hole (2), and a steel mesh sheet (4) is hoisted into the casing (3) by a crane, a steel cage (6) is fixed in the casing (3) and arranged coaxially with the casing (3), and a grouting steel pipe (8) is placed in the steel cage (6); S3, push the two moving rods (14) to move the two moving rods (14) away from each other, so that the support rods (13) welded to the lower half of the two moving rods (14) extend out of the grouting steel pipe (8) and the steel cage (6), fix the two moving rods (14) relative to each other, fill the space between the casing (3) and the steel cage (6) with the crushed stone filling material (5) matched in S1, make the pile height of the crushed stone filling material (5) higher than the height between the support rod (13) farthest from the bottom of the pile hole (2) and the bottom of the pile hole (2), vibrate the casing (3) with a vibrating pile driver, gradually pull out the pipe while vibrating, and control the pulling speed within the range of 0.8-1.0 m / min, use a rammer and lift it to a certain height, and let it fall freely to impact the crushed stone filling material (5) in the casing (3), and ram it multiple times to make the materials compacted and vibrated; S4, pushing the other two opposite moving rods (14) to move the other two opposite moving rods (14) away from each other, the support rods (13) welded to the upper half of the two moving rods (14) extend out of the grouting steel pipe (8) and the steel cage (6), fixing the other two opposite moving rods (14), filling the space between the casing (3) and the steel cage (6) with gravel filler (5) again, vibrating the casing (3) with a pile driver, gradually pulling out the casing, compacting the gravel filler (5) with a rammer, and squeezing and compacting the steel mesh (4) and the soil around the pile hole (2); S6, pouring concrete slurry into the grouting steel pipe (8), so that the concrete slurry flows out through the slurry outlet hole (9) to the space between the steel cage (6) and the steel mesh (4), and waiting for the concrete slurry to solidify to form a gravel pile; S7, after the gravel piles in S6 are inspected and qualified, a positioning ring (17) sleeved on the grouting steel pipe (8) is fixed on the top of the grouting steel pipe (8), two adjacent positioning rings (17) fixed on the steel cage (6) are connected by using a connecting pipe (21), the buckle is unlocked, and the push rod (25) installed in the connecting pipe (21) pushes the support block (23), so that the support block (23) moves outward and contacts the positioning ring (17), and the anchor rod (29) passes through the push rod (25) and the connecting pipe (21) and is anchored on the ground, so that multiple gravel piles are connected into one, and a layer of gravel is laid on the top of the gravel pile to form a 20 cm gravel cushion layer and compacted to form the required composite foundation.

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