A regular bottom-expanded size capsule injection bag and capsule injection molding method

Abstract

The present invention relates to the field of building construction, and specifically to a regular bottom-expanded size bladder injection bag, comprising a slurry bladder bag, an upper partition, a grouting pipe, a drainage network, a drainage pipe and a limit strip, wherein an upper partition is arranged at the upper end of the slurry bladder bag, a hole cover is arranged in the middle of the upper partition, a conveying rod is detachably arranged on the upper partition at the periphery of the hole cover, a grouting pipe is arranged on the hole cover, the grouting pipe is connected with the inside of the slurry bladder bag, a drainage network is arranged on the outside of the slurry bladder bag, the drainage network is connected to the drainage pipe through the upper partition and the hole cover, the drainage pipe is arranged on the hole cover, a bottom partition or a pile shoe is arranged at the lower end of the slurry bladder bag, and a limit strip is located on the outside of the slurry bladder bag and is hingedly arranged on the upper partition. It also relates to a regular bottom-expanded size bladder injection molding method. The present invention can effectively control the unfolding shape of the bladder injection bag, can realize the regularization and optimization of the shape of the pile end enlarged head, can accelerate the compaction of the soil, expand the compaction range of the soil and increase the compaction space, and improve the bearing capacity of the pile end and the pile as a whole.

Description

Technical Field

[0001] The invention relates to the field of building construction, and in particular to a bladder injection bag with a regular expanded bottom size and a bladder injection molding method. Background Art

[0002] Expanded base piles have high bearing capacity, so people not only make full use of geological conditions, but also try to create conditions to use expanded base piles. Studies have shown that the size of the expanded head space of the expanded base pile and the different construction methods have a great difference in the degree of improvement in its bearing capacity.

[0003] There are two construction methods for enlarging the head space: soil excavation and compaction. From the perspective of improving bearing capacity, the compaction method will compact the lateral soil of the enlarged head space, and the lateral compaction is equivalent to adding constraints to the soil below the enlarged head. Therefore, the compaction method is better than the soil excavation method. Studies in recent years have shown that the soil at the pile end is hard, and the lateral friction resistance on the pile side, especially near the pile end, has increased to a certain extent, thereby greatly improving the bearing capacity of the pile. How to compact the soil at the pile end and the pile side here into an enlarged head space to maximize the pile bearing capacity is the pursuit of technical personnel in the industry.

[0004] The Chinese patent "Pre-contracting device for pre-bearing piles" (ZL92202624.6) is a technology for expanding the head space by squeezing and compacting the soil. However, due to the limitation of the compressibility of the soil, the expanded head space formed by this compaction method is limited. Moreover, the spatial shape formed by this method is not optimal and difficult to control, which brings certain uncertainties to the design. Therefore, although this technology has improved the bearing capacity of the pile to a certain extent, it has not been well promoted and applied.

[0005] In order to solve the shortcomings of this technology, a regular bottom-expanding size injection molding method is proposed. Summary of the invention

[0006] In order to solve the above-mentioned technical problems, the present invention provides a bladder injection bag with a regular expanded bottom size and a bladder injection molding method, which can effectively control the unfolding shape of the bladder injection bag, realize the regularization and optimization of the shape of the enlarged head at the pile end, accelerate the compaction of the soil, expand the compaction range of the soil and increase the compaction space, thereby improving the bearing capacity of the pile end and the pile as a whole.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A regular bottom-expanded size bladder injection bag comprises a slurry bag, an upper partition, a grouting pipe, a drainage network, a drainage pipe and a limit strip. The upper partition is arranged at the upper end of the slurry bag, a hole cover is arranged in the middle of the upper partition, and a conveying rod is detachably arranged on the outer periphery of the hole cover on the upper partition. The grouting pipe is arranged on the hole cover, and the grouting pipe is connected with the inside of the slurry bag. The drainage network is arranged on the outside of the slurry bag, and the drainage network is connected to the drainage pipe through the upper partition and the hole cover. The drainage pipe is arranged on the hole cover. A bottom partition or a pile shoe is arranged at the lower end of the slurry bag. A plurality of limit strips are located on the outside of the slurry bag and are hingedly arranged on the upper partition. A surrounding tube is arranged on the upper partition.

[0009] In a further preferred embodiment, a limit stopper is provided at a hinge of the upper partition corresponding to the limit strip, and a side of the limit stopper facing the limit strip is an inclined surface.

[0010] In a further preferred embodiment, the upper partition is provided with a plurality of radially arranged water holes, one end of the water holes is connected to a drainage network, and the hole cover is provided with an annular groove corresponding to the other end of the water holes, and the annular groove is connected to the drainage pipe.

[0011] In a further preferred embodiment, the drainage network includes a plurality of drainage strips arranged circumferentially and longitudinally, and the upper ends of the drainage strips arranged longitudinally are connected to the water holes of the upper partition.

[0012] In a further preferred embodiment, a pressure relief valve is provided in the middle of the bottom diaphragm; and pressure relief valves are symmetrically provided on both sides of the pile shoe.

[0013] A method for forming a capsule injection bag with a regular bottom expansion size based on the capsule injection bag comprises the following steps:

[0014] Step 1: Determine the size of the enlarged head and the size of the injection bag: The size of the enlarged head should be designed according to the bearing capacity requirements of the foundation pile, and the compaction effect of the soil at the pile end should be considered; the length of the limit strip is determined according to the size of the cone on the enlarged head, and the shape and size of the injection bag after it is fully expanded is determined according to the shape and size of the enlarged head; the size of the upper partition and the bottom partition or pile shoe is determined according to the pile diameter;

[0015] Step 2: Determine the reserved space when the bladder injection bag is sunk: Based on soil consolidation theory and engineering experience, estimate the maximum space that can be formed by the soil at the pile end under the extrusion of the proposed bladder injection bag, and take the difference between the designed enlarged head volume and the extruded space as the space to be pre-occupied by the bladder injection bag after it sinks to the bottom of the hole - that is, the reserved space. The reserved space is set because according to the designed grouting pressure, the bladder injection bag cannot expand and compact the soil to reach the enlarged head volume, but in order to achieve the size of the expanded bottom end, the space volume that is not obtained by squeezing the soil must be reserved in advance, and this volume is achieved through the reserved space of the bladder injection bag;

[0016] The shape of the reserved space of the capsule injection bag is a cylinder. The diameter D is the diameter of the inscribed circle of the circle surrounded by the limit bar hanging naturally. The height h is calculated by the following formula:

[0017]

[0018] Where V0 is the design value of the enlarged head volume, cm 3 ;

[0019] V is the volume of space formed by the compaction of soil under bladder injection, cm 3 , take the strip load with a semi-infinite space width of h0 (the load value is the slurry pressure in the injection bag) and multiply the vertical compression of the soil by or The value of

[0020] D0 is the diameter of the cylindrical section of the enlarged head;

[0021] h0 is the total height of the enlarged head, which is the sum of the heights of the two frustum sections and the cylindrical section;

[0022] D is the diameter of the reserved space of the capsule injection bag, which is the diameter of the inscribed circle formed by the naturally hanging limit bar;

[0023] Step 3: Assemble the sac bag, limit the sac bag within the range surrounded by the naturally hanging limit bar, symmetrically set nylon buckle drawstrings on the limit bar in the height direction of the reserved space to hold the folded sac bag; remove the hole cover and fill the slurry bag with pebbles, and then install the hole cover to ensure the height and radial width of the reserved space; connect the drainage pipe and the grouting pipe; connect the conveying rod;

[0024] Step 4: Drill the pile hole;

[0025] Step 5: Overdrilling: When the space created by the injection-injection extrusion of soil is smaller than the volume of the pile bottom expansion, it is necessary to drill out the insufficient space, which is called overdrilling. Overdrilling depth h 超 It can be estimated by the following formula:

[0026]

[0027] Where D 孔 is the drilling diameter;

[0028] D is the diameter of the reserved space of the capsule injection bag;

[0029] h is the height of the space reserved for the capsule injection bag;

[0030] Step 6: Lower the capsule injection bag: Slowly lower the capsule injection bag to the bottom of the hole through the conveying rod, and keep the conveying rod centered;

[0031] Step 7: Pour the pile concrete, remove the delivery rod, and implement the bladder injection and bottom expansion after 7 to 28 days:

[0032] (a) preparing slurry, cement: water: additive = 1: (0.5-0.7): 0.08, cement is PO52.5 ordinary Portland cement, and additive is UEA expansion agent;

[0033] (b) Connect the grouting pipe to the grouting pump;

[0034] (c) Grouting is first intermittently injected into the slurry bag through the grouting pipe to remove the air in the slurry bag; then continuous grouting is performed, and the slurry bag stretches the Velcro rope during the opening process, and the slurry bag squeezes the soil toward the bottom and sides, generating excess pore water pressure in the soil; as the water and / or gas in the soil passes through the drainage network on the outer surface of the slurry bag, it enters the upper partition and is then discharged to the ground along the drainage pipe;

[0035] Step 8: After the slurry in step 7 solidifies, fill the drain pipe with the slurry;

[0036] Step 9: Cut off the drainage pipe and grouting pipe at the top of the pile, and cut off the drainage pipe and grouting pipe along the pile head.

[0037] In a further preferred embodiment, in step 7, when the limit strip is fully opened and the grouting volume basically reaches the maximum design capacity of the bladder bag, the grouting pressure will rise sharply. At this time, the grouting is stopped and the grouting pressure is maintained for 2 to 6 hours, or until there is no water discharged from the drain pipe. The slurry is injected into the slurry with gradually increased pressure. When the slurry in the slurry bag exceeds a certain high pressure value, the slurry will be ejected from the pressure relief valve and will compact and split the pile end soil and the periphery of the bladder bag. This can be implemented several times to further strengthen the pile end soil. During the last injection, the drain pipe is closed, and slurry that can solidify the cement slurry in a short time can be injected. When the slurry input is basically 0, the grouting pipe is closed.

[0038] In a further preferred embodiment, if the grouting pressure reaches the design value but the grouting volume is far from the maximum design capacity of the capsule bag, the grouting pipe is closed, and additional injection is performed after 2 to 6 hours when the extremely high superstatic pore water pressure in the soil around the capsule bag has been largely dissipated or even basically dissipated, so that the grouting volume finally reaches the maximum design capacity of the capsule bag.

[0039] In a further preferred embodiment, for reinforced concrete pile foundations, before pouring the pile body concrete in step 7, a steel cage is lowered.

[0040] Through the above technical solution, the beneficial effects of the present invention are:

[0041] 1. The expansion shape of the bladder bag provided by the present invention is controllable and can achieve a pre-designed shape. An upper baffle is provided at the upper end of the pulp bag, and a bottom baffle or a pile shoe is provided at the lower end. A limit strip is provided on the upper baffle. When the pulp bag is expanded, the upper baffle and the limit strip limit the upper shape of the pulp bag, and the bottom baffle or the pile shoe limits the lower shape of the pulp bag, so that the expanded pulp bag forms an upper truncated cone section, a middle cylindrical section, and a lower truncated cone section to achieve the designed shape, and realize the regularization and optimization of the shape of the pile end enlarged head.

[0042] 2. The bladder bag provided by the present invention includes a drainage network arranged on the surface of the slurry bladder bag, and the drainage network is connected to the drainage pipe through the upper partition and the hole cover. When the slurry bladder bag is unfolded, that is, the bladder bag is unfolded, the water and / or gas in the soil is gathered through the drainage network and discharged through the drainage pipe, thereby reducing the excess pore water pressure formed in the surrounding soil when the bladder bag is unfolded and causing it to gradually dissipate, thereby quickly compacting the soil.

[0043] 3. The slurry bag of the bladder injection bag provided by the present invention is provided with a bottom partition or a pile shoe at the lower end, and a pressure relief valve is provided on the bottom partition, and a pressure relief valve is provided on the pile shoe. When the slurry in the slurry bag exceeds a certain high pressure value, the slurry will be sprayed out from the pressure relief valve to compact and split the pile end soil and the periphery of the bladder injection bag, thereby further strengthening the pile end soil.

[0044] 4. The injection molding method provided by the present invention can be suitable for soil layers with poor drilling and expansion stability, especially soft soil, eliminate or reduce the adverse effects of pile end sediment and soil disturbance, improve the bearing capacity of the pile end, give full play to the bearing coupling effect of the pile end and the pile side, improve the overall bearing capacity of the pile, regularize and optimize the shape of the enlarged head, and enlarge the size of the enlarged head. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the cross-sectional structure of a regular bottom-expanded size capsule injection bag after being unfolded according to the present invention;

[0046] Figure 2 It is a schematic cross-sectional structure diagram of the bladder injection bag with pile shoes after being unfolded;

[0047] Figure 3 It is a schematic diagram of the cross-sectional structure of the upper partition, the pulp sac bag and the limiting strip;

[0048] Figure 4 1 is a schematic diagram of the top structure of the upper partition;

[0049] Figure 5 It is a schematic diagram of the cross-sectional structure of a bladder injection bag with a pile shoe;

[0050] Figure 6 It is a schematic diagram of the cross-sectional structure of a capsule injection package with a bottom partition;

[0051] Figure 7 The figure is a diagram of the process of forming a reinforced concrete foundation pile by bladder injection molding and bladder injection bottom expansion, wherein, figure (a) is drilling and hole formation, figure (b) is over-drilling and stirring, figure (c) is lowering the bladder injection bag and the steel cage, figure (d) is pouring concrete; figure (e) is bladder injection and bottom expansion;

[0052] Figure 8 The figure is a diagram of the pile formation process of the plain concrete pile by bladder injection molding and bladder injection bottom expansion, wherein, Figure (a) shows the drilling hole, Figure (b) shows the over-drilling stirring, Figure (c) shows the lowering of the bladder injection bag, Figure (d) shows the pouring of concrete; Figure (e) shows the bladder injection bottom expansion.

[0053] The numbers in the accompanying drawings are: 1 is a slurry bag, 2 is an upper partition, 201 is a limit block, 202 is a water hole, 3 is a grouting pipe, 4 is a drainage pipe, 5 is a limit strip, 601 is a bottom partition, 602 is a pile shoe, 7 is a hole cover, 701 is an annular groove, 8 is a conveying rod, 9 is a surrounding tube, 10 is an enlarged head, 11 is a steel cage, 12 is an interface, 13 is a pressure relief valve, 14 is a connecting piece, and 15 is a drainage strip. DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0055] In the description of the present invention, it should be understood that the terms "left", "right", "up", "down", "horizontal", "vertical" and the like indicate directions or positional relationships based on the attached Figure 1 The orientation or positional relationship shown is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0056] like Figures 1 to 8 As shown, this embodiment provides a regular bottom-enlarged size slurry bag, including a slurry bag 1, an upper partition 2, a grouting pipe 3, a drainage network, a drainage pipe 4 and a limit strip 5.

[0057] The pulp bag 1 is made of canvas with glue brushed on the inner side. The upper end of the pulp bag 1 is provided with the upper partition 2 and is firmly connected to the upper partition 2. The lower end of the pulp bag 1 is provided with a bottom partition 601 or a pile shoe 602.

[0058] The upper partition 2 is made of reinforced concrete panel with a thickness of 50 to 100 mm. The diameter of the upper partition 2 is slightly smaller than the diameter of the drilled hole by 5 to 10 cm. A circular hole is reserved in the middle of the upper partition 2, and a pre-buried steel pipe type interface 12 is arranged in the circular hole. The upper end of the interface 12 extends out of the upper partition 2 and is provided with an external thread. The lower end of the interface 12 is provided with an internal thread. The upper partition 2 is provided with a hole cover 7 through the internal thread of the interface, and a conveying rod 8 is provided through the external thread of the interface. The conveying rod 8 is a hollow annular tube; a surrounding tube 9 is arranged around the upper partition 2. The surrounding tube 9 is 200 to 300 mm high. The surrounding tube 9 is a cylindrical shape made of rectangular thin iron sheet. When the rectangular iron sheet is rolled, there are overlapping parts at both ends of the iron sheet. The lower end of the iron sheet is connected to the upper partition 2. When concrete is poured in the hole, the upper end of the surrounding tube 9 will open into a trumpet shape, cutting off the connection between the concrete and the bladder injection bag near the wall of the drilled hole, preventing the bottom soil from squeezing into the upper partition 2.

[0059] The hole cover 7 is made of concrete material, and the grouting pipe 3 is arranged on the hole cover 7. The grouting pipe 3 is connected with the inside of the pulp bag 1. The drainage network is arranged on the outside of the pulp bag 1. The drainage network is connected to the drainage pipe 4 through the upper partition 2 and the hole cover 7. The drainage pipe 4 is arranged on the hole cover 7.

[0060] The grouting pipe 3 is a PVC pipe. After the sac injection bag is lowered, the grouting pipe 3 should extend upward to the ground surface. The surface section of the grouting pipe 3 is provided with a switch device to control the entry of slurry and the discharge of air.

[0061] The drainage pipe 4 is made of PVC pipe. After the bladder is placed, the drainage pipe 4 should extend upward to the ground. The surface section of the drainage pipe 4 is connected to a vacuum pump, which accelerates the discharge of groundwater in the pile expansion area, that is, accelerates its consolidation, so that the soil is further strengthened.

[0062] The limit strip 5 is located outside the pulp bag 1 and is hingedly arranged on the upper partition 2. The limit strip 5 is made of steel bars. The number of limit strips 5 is preferably 6 to 12 (the number of strips is related to the size of the enlarged head), and is evenly distributed along the outer edge of the upper partition 2. Regarding the hinge structure of the limit strip 5 and the upper partition 2: a connector 14 is embedded in the upper partition 2. The connector 14 is made of steel bars and is connected to the steel bars in the upper partition 2. The limit strip 5 can be hinged to the upper partition 2 through the connector 14.

[0063] As mentioned above, the upper partition 2 is provided with a limit stop 201 at the hinge corresponding to the limit strip 5, and the limit stop 201 has an inclined surface on the side facing the limit strip 5, and the opening range of the limit strip 5 is limited by the inclined surface. When the pulp bag 1 is unfolded, the limit strip 5 forms a limit on the upper part of the pulp bag 1, limiting the shape of the upper end of the pulp bag 1, so that the upper end of the pulp bag forms a truncated cone section, the middle part of the pulp bag 1 forms a large-headed cylindrical section, and the lower end of the pulp bag 1 is limited by the bottom partition 601 or the pile shoe 602 to form a truncated cone section. The composite shape of the upper cone, middle cylinder and lower cone of the pulp bag can be pre-set according to the shape of the enlarged head of the expanded bottom pile, and the pre-set shape is formed after unfolding, that is, the shape of the enlarged head of the expanded bottom pile, such as Figure 1 and Figure 2 shown.

[0064] Specifically, the upper partition 2 is provided with a plurality of radially arranged water holes 202, the water holes 202 are located inside the upper partition 2, the lower ends of the water holes 202 are connected to the drainage network, the hole cover 7 is provided with an annular groove 701 corresponding to the upper end of the water hole 202, the annular groove 701 is connected to the drainage pipe 4, and the drainage network is connected to the drainage pipe 4 through the water holes 202 and the annular groove 701.

[0065] Furthermore, the drainage network includes a plurality of drainage strips 15 arranged circumferentially and longitudinally. The drainage strips 15 are conventional narrow geotextile drainage strips. The drainage strips can be glued to the pulp bag 1. Since the lower end of the pulp bag 1 is provided with a bottom baffle 601 or a pile shoe 602, drainage strips are also glued to the bottom surface of the bottom baffle 601 or the side of the pile shoe 602. There can be 2 to 4 longitudinal drainage strips, and 1 to 2 circumferential drainage strips can be provided in the cylindrical section and the upper truncated cone section of the enlarged head of the pulp bag 1. The upper end of the longitudinal drainage strip is inserted into the water hole 202 of the upper baffle 2, and the hole opening is sealed and connected with glue.

[0066] If a bottom partition 601 is provided at the lower end of the slurry bag 1, a slurry pressure relief valve 13 is provided at the center of the bottom partition 601. When the slurry in the slurry bag exceeds a certain high pressure value, the slurry will be ejected from the pressure relief valve 13. A pile shoe 602 can be used at the lower end of the slurry bag 1 to replace the bottom partition 601. If a pile shoe 602 is provided, then: the pile shoe is an ordinary concrete pile shoe. If the size of the pile shoe causes the pile shoe to be too heavy, the pile shoe 602 can be made hollow, and a slurry pressure relief valve 13 is provided on the side of the pile shoe. When the slurry in the slurry bag exceeds a certain high pressure value, the slurry will be ejected from the pressure relief valve 13, and the pile end soil and the periphery of the bladder injection bag will be compacted. The pile shoe is a common component in pile foundation engineering and will not be described in detail here.

[0067] About the closing and opening of the capsule injection bag:

[0068] When the capsule injection bag is lowered into the hole and sunk to the bottom of the hole, the capsule injection bag must be folded first, and a Velcro drawstring is set on the limit strip 5 in the height direction of the reserved space to hold the folded capsule injection bag. Unscrew the hole cover 7 and fill the pulp capsule bag 1 with pebbles, and then tighten the hole cover 7, so as to ensure the height and radial width of the reserved space;

[0069] When the slurry is injected into the capsule injection bag, the reserved space is first filled with slurry. As the slurry injection increases, the shrunk capsule injection bag tends to expand, the Velcro will be disengaged, and the limit strip 5 will be loosened. Continue grouting, the capsule injection bag will further expand under the pressure of expansion, and the cycle will continue until it is fully expanded. After expansion, the upper part of the capsule injection bag forms a truncated cone section, the middle part forms a large-headed cylindrical section, and the lower end forms a truncated cone section.

[0070] A method for regularly expanding the bottom size of the capsule injection molding comprises the following steps:

[0071] Step 1: Determine the size of the enlarged head and the size of the bladder bag: The size of the enlarged head, i.e. the height of the upper cone, the diameter and height of the middle cylinder, should be designed according to the bearing capacity requirements of the foundation pile, and the compaction effect of the soil at the pile end should be considered; determine the length of the limit strip 5 based on the size of the cone on the enlarged head, and determine the shape and size of the bladder bag after it is fully unfolded based on the shape and size of the enlarged head; determine the size of the upper partition 2 and the size of the bottom partition 601 or pile shoe 602 based on the pile diameter.

[0072] Step 2: Determine the reserved space when the bladder bag is sunk: Based on soil consolidation theory and engineering experience, estimate the maximum space that can be formed by the soil at the pile end under the extrusion of the proposed bladder bag, and take the difference between the designed enlarged head volume and the extruded space as the space to be pre-occupied by the bladder bag after it sinks to the bottom of the hole - that is, the reserved space. To put it more specifically, the reserved space is set because the designed grouting pressure cannot be used to expand and compact the soil to reach the enlarged head volume, but in order to achieve the size of the expanded bottom end, the space volume that is not obtained by squeezing the soil must be reserved in advance, and this volume is achieved through the reserved space of the bladder bag;

[0073] The shape of the reserved space of the capsule injection bag is a cylinder. The diameter D is the diameter of the inscribed circle of the circle surrounded by the limit bar hanging naturally. The height h is calculated by the following formula:

[0074]

[0075] Where V0 is the design value of the enlarged head volume, cm 3 ;

[0076] V is the volume of space formed by the compaction of soil under bladder injection, cm 3 , take the strip load with a semi-infinite space width of h0 (the load value is the slurry pressure in the injection bag) and multiply the vertical compression of the soil by or The value of

[0077] D0 is the diameter of the cylindrical section of the enlarged head;

[0078] h0 is the total height of the enlarged head, which is the sum of the heights of the two frustum sections and the cylindrical section;

[0079] D is the diameter of the reserved space of the capsule injection bag, which is the diameter of the inscribed circle formed by the naturally hanging limit bar 5.

[0080] Step 3: Assemble the capsule injection package. Specifically:

[0081] (a) Processing and preparing various parts for capsule injection packaging;

[0082] (b) firmly connecting the pulp bag 1 to the upper partition 2 and the bottom partition 601 or the pile shoe 602;

[0083] (c) The circumferential drainage strip is closed and pasted on the outside of the pulp bag 1, and the longitudinal drainage strip is pasted on the outside of the pulp bag 1, the lower side of the bottom partition 601 or the side of the pile shoe 602. The upper end of the longitudinal drainage strip is inserted into the water hole of the partition and sealed tightly with glue; the intersection of the circumferential drainage strip and the longitudinal drainage strip is opened to form a drainage network;

[0084] (d) connecting the limit strip 5 and setting the surrounding tube 9;

[0085] (e) The cystic injection bag is folded. The cystic injection bag is confined within the range surrounded by the naturally hanging limit steel bar, and nylon hook and loop drawstrings are symmetrically arranged on the limit bar 5 in the height direction of the reserved space to hold the folded cystic injection bag. Unscrew the hole cover 7 and fill the pulp cystic bag with pebbles, and then tighten the hole cover 7 to ensure the height and radial width of the reserved space;

[0086] (f) connecting the drainage pipe 4 and the grouting pipe 3;

[0087] (g) Connect the conveying rod 8.

[0088] Step 4: Drill the pile hole; Figure 7 (a) or Figure 8 (a) shown.

[0089] Step 5: Overdrilling: When the space created by the injection-injection extrusion of soil is smaller than the volume of the pile bottom expansion, it is necessary to drill out the insufficient space, which is called overdrilling. Overdrilling depth h 超 It can be estimated by the following formula:

[0090]

[0091] Where D 孔 is the drilling diameter;

[0092] D is the diameter of the reserved space of the capsule injection bag;

[0093] h is the height of the space reserved for the capsule injection bag.

[0094] Step 6: Lowering the capsule injection bag: Slowly lower the capsule injection bag to the bottom of the hole through the conveying rod 8, and keep the conveying rod 8 centered.

[0095] Step 7: Pour the pile concrete, remove the delivery rod 8, and implement the bladder injection and bottom expansion after 7 to 28 days:

[0096] (a) Prepare slurry, mainly cement slurry, with an initial setting time of more than 12 hours. The slurry includes cement, water and additives, cement: water: additive = 1: (0.5-0.7): 0.08, the cement is PO52.5 ordinary Portland cement, and the additive is UEA expansion agent with micro expansion and increased fluidity.

[0097] (b) connecting the grouting pipe 3 to the grouting pump;

[0098] (c) Intermittent grouting is first performed into the slurry bag 1 through the grouting pipe 3 to remove the air in the slurry bag 1; then continuous grouting is performed, and the slurry bag 1 opens the nylon fastener rope during the opening process, and the bag squeezes the soil toward the bottom and sides, generating excess pore water pressure in the soil. As the water and / or gas in the soil passes through the drainage network on the outer surface of the slurry bag 1, enters the water holes in the upper partition 2, and then is discharged to the ground along the drainage pipe 4, the excess pore water pressure gradually dissipates and the soil is gradually compacted. In order to accelerate the consolidation and compaction of the soil and the formation of the hole expansion space, the drainage pipe can be connected to a vacuum pump to form a certain vacuum at the pile end to accelerate the discharge of soil moisture in the hole expansion area;

[0099] (d) As the grouting volume and grouting pressure continue to increase, the grouting bag is further expanded, and the grouting bag continuously squeezes the soil outward, new excess pore water pressure is continuously generated, and superimposed on the excess pore water pressure that has not dissipated. At the same time, the drainage of the drainage network will gradually dissipate the excess pore water pressure in the soil, and the surrounding soil will also be continuously compacted, and the head space will continue to expand. Therefore, during the grouting period, it is a process of interaction between the generation and dissipation of the excess pore water pressure of the soil in the grouting bag area, and it is also a process of continuous expansion of the head space. This process is fast at first and then slow;

[0100] (e) As the grouting proceeds, the slurry bag 1 continues to expand and gradually touches the limit block 201 one after another, so that the limit bar 5 provides a reaction force to restrict the development of the upper truncated cone side of the slurry bag. When the limit block 201 is fully utilized and the grouting volume basically reaches the maximum design capacity of the slurry bag, the grouting pressure will rise sharply. At this time, stop the grouting and maintain the grouting pressure for 2 to 6 hours or longer, or until there is no water discharged from the drain pipe 4, continue and gradually increase the pressure to inject cement slurry. When the slurry in the slurry bag 1 exceeds a certain high pressure value, the slurry will be ejected from the pressure relief valve 13, and the pile end soil and the periphery of the slurry bag will be compacted and split. This can be implemented several times to further strengthen the pile end soil. During the last injection, close the drain pipe 4, and inject slurry that can solidify the cement slurry in a short time, such as water glass. When the slurry input is basically 0, close the grouting pipe. At this point, the slurry bag has been fully formed;

[0101] (f) If the grouting pressure reaches the design value but the grouting volume is far from the maximum design capacity of the bladder bag, close the grouting pipe and wait for 2 to 6 hours until the extremely high super-static pore water pressure in the soil around the bladder bag has dissipated significantly or even basically dissipated, then perform additional injection to eventually make the grouting volume reach the maximum design capacity of the bladder bag.

[0102] Step 8: After the slurry in step 7 solidifies, open the drain pipe 4, insert a small tube into the drain pipe 4 to the bottom of the drain pipe 4, and pull out the small tube while injecting cement slurry to fill the space inside the drain pipe 4 with the slurry.

[0103] Step 9: Cut off the drainage pipe 4 and grouting pipe 3 at the top of the pile, and cut off the drainage pipe 4 and grouting pipe 3 along the pile head.

[0104] For reinforced concrete piles, before pouring the pile body concrete in step 7, the steel cage 11 is lowered. Figure 7 (c) as shown.

[0105] The advantages of this bladder injection molding method in the construction of expanded piles are as follows:

[0106] 1. Suitable for soil layers with poor drilling (hole expansion) stability, especially soft soil. Under many geological conditions, such as soft soil and underwater, it is difficult to expand the bottom of the hole with existing technology, so it is usually impossible to construct expanded bottom piles. However, the bladder injection bag and bladder injection molding method can not only realize the construction of expanded bottom piles, but also meet the requirements on size and shape. Although the "Pre-contracting device for pre-bearing piles" (ZL92202624.6) can realize soft soil and underwater expanded bottom piles, the expanded bottom shape and size are limited. The reasons are as follows:

[0107] (1) The expansion of pre-contracted grouting is a hemispherical shape under ideal conditions;

[0108] (2) The slurry solidifies too quickly during pre-construction. The technology described in the "pre-construction device for pre-bearing piles" is to inject water glass and cement slurry in sequence, and mix them freely in the pre-construction (equivalent to the capsule injection bag of this technology) deep underground. Since the two slurries will solidify quickly after meeting, the uniformity of their mixing cannot be guaranteed. Even if they are modulated so that they will not solidify quickly after meeting, the later injected slurry will rush into the first slurry without sufficient stirring conditions. It is difficult to ensure the uniformity of their mixing even if the two are mixed freely, thus affecting the realization of their shape and size;

[0109] (3) Soil compaction takes time. The pre-construction expands due to the injection of slurry, which produces squeezing pressure on the surrounding soil. The first to bear this squeezing pressure is the groundwater in the soil, which is converted into excess pore water pressure. According to Terzaghi consolidation theory, if the excess pore water pressure does not dissipate, the soil will not be compacted and the pre-construction cannot be fully developed. The dissipation of excess pore water pressure takes time. Water glass and cement slurry are injected successively and solidify quickly. The dissipation time of excess pore water pressure cannot be guaranteed, the pre-construction cannot be fully developed, and its shape and size are restricted;

[0110] (4) Soil compaction space is limited. Soil compaction is the result of water discharge from the soil and the reduction of the porosity. However, the porosity of the soil at the pile end is generally 0.6-0.8, soft soil is about 1.0-1.2, and the sediment at the bottom of the hole is about 0.8-1.0. The bottom expansion size obtained by relying solely on soil compaction is limited.

[0111] This technology controls the shape of the expanded bottom by adding a limit stopper 201 and a limit strip 5, uses a drainage network to accelerate soil compaction, expands the compacted soil range and increases the compaction space, relies on the setting of reserved space to expand the expanded bottom space, and the relatively long single slurry solidification time allows the bladder injection package to be fully adjusted and expanded. Therefore, this method is significantly better than the "pre-contracting device for pre-bearing piles" technology.

[0112] 2. Eliminate or reduce the adverse effects of pile end sediment and soil disturbance. It is well-known professional common sense that the bottom sediment and soil disturbance have a great influence on the pile bearing capacity. Conventional bored piles are usually unable to completely eliminate the influence of the bottom sediment and soil disturbance because the drainage path of the bottom sediment and soil disturbance is cut off or greatly weakened when the concrete is poured, so it takes a long time to complete the reconsolidation of the bottom sediment and soil disturbance. On the other hand, the reconsolidation pressure of the bottom sediment and soil disturbance is mainly the gravity of the upper concrete, and the consolidation pressure is not large. Moreover, the concrete solidifies relatively quickly. These factors make it difficult for the bottom sediment and soil disturbance to reconsolidate as before. The "pre-contracting device for pre-bearing piles" technology and this technology are to form a consolidation pressure far greater than the gravity of the upper concrete by injecting slurry under certain solidification conditions of the pile body concrete, so the bottom sediment and soil disturbance reconsolidation effect is good. This method has good drainage conditions and can provide greater effective consolidation pressure and effective consolidation time than the "pre-contracting device for pre-bearing piles" technology, and the effect is better than the "pre-contracting device for pre-bearing piles" technology.

[0113] 3. Improve the bearing capacity of the pile end. The bearing capacity of the pile end depends on both the bottom area of ​​the pile end and the hardness and density of the soil under and on the sides of the pile end. This technology has a large range and a large degree of compaction on the soil under and on the sides of the pile end. In addition, the large size of the enlarged head significantly improves the bearing capacity of the pile end. Because this method is superior to the same factors of similar technologies in improving the soil under and on the sides of the pile end, the pile end bearing capacity improved by this factor alone has a greater advantage over similar technologies such as the "pre-contracting device for pre-bearing piles" technology.

[0114] 4. Give full play to the coupling effect of pile end and pile side bearing to improve the overall bearing capacity of the pile. The force transmission mechanism of conventional piles is: when the upper load is transmitted to the pile top, the pile side friction resistance is first exerted. As the upper load increases, the side friction resistance gradually increases and extends to the deep part of the pile. The pile end resistance is still very small. When the displacement of the pile under the vertical load exceeds 8-10mm, the side friction resistance gradually decreases. The displacement increases and the pile end resistance gradually increases. Even if it reaches the limit state, it is not the superposition of the maximum pile end resistance and the reduced pile side friction resistance, because the soil resistance at the pile end can only reach the maximum when the soil is compressed and deformed to 20-30mm, and the pile side friction resistance will be significantly reduced when such a displacement is reached. This technology improves the strength of the soil at the pile end and reduces the compression deformation required for the pile end to reach the maximum resistance, so that when the pile end reaches the maximum resistance, the side friction resistance is also at an overall high value.

[0115] 5. Enhance the side friction effect of piles. Studies in recent years have shown that strengthening the soil at the pile end can produce a side friction strengthening effect, especially the side friction strengthening effect in the pile end area. This technology has a significant effect on strengthening the soil at the pile end, so the side friction strengthening effect will be more obvious, thereby improving the overall bearing capacity of the pile.

[0116] 6. Regularization and optimization of the shape of the enlarged head, and super-large size of the enlarged head. This technology controls the shape of the enlarged bottom end by adding a limit device, uses the drainage network to accelerate soil compaction, expand the compacted soil range and increase the compaction space, relies on the setting of reserved space to expand the bottom expansion space, and uses a relatively long single slurry solidification time to allow the bladder injection package to fully adjust and expand. Therefore, this technology can easily realize the regularization and optimization of the shape of the enlarged head, as well as the super-large size of the enlarged head. This advantage is not available in the "pre-contracting device for pre-bearing piles" technology.

[0117] 7. The existence of the pile shoe and the setting of the reserved space can realize the shape of the enlarged head with a slightly upward periphery. This shape avoids the problem of the flat-bottomed enlarged head: the edge soil enters the plastic state first, which reduces the resistance of the pile end. According to foundation engineering theory, the reaction force of the foundation soil of the flat-bottomed foundation is uneven and concave arc-shaped. The reaction force of the foundation soil at the peripheral edge is the largest, and the reaction force of the foundation soil in the middle is the smallest. That is, the soil layer at the bottom edge of the enlarged head where the reaction force of the foundation soil is the largest is prone to stress concentration and the appearance of plastic hinges. As the load increases, the plastic hinge at the edge expands to the middle of the pile bottom, thereby reducing the end resistance value of the pile end soil. The shape of the enlarged head with a slightly upward periphery can just change the distribution of the reaction force of the foundation soil at its bottom edge, making it more uniform, thereby alleviating the occurrence of the plastic hinge phenomenon and improving the bearing capacity of the pile.

[0118] The embodiments described above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structures, features and principles described in the patent scope of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A regular bottom-enlarged size capsule injection bag, characterized in that: The invention comprises a pulp bag (1), an upper partition (2), a grouting pipe (3), a drainage network, a drainage pipe (4) and a limit strip (5), wherein the upper partition (2) is arranged at the upper end of the pulp bag (1), a hole cover (7) is arranged in the middle of the upper partition (2), a conveying rod (8) is detachably arranged on the periphery of the hole cover (7) of the upper partition (2), the grouting pipe (3) is arranged on the hole cover (7), and the grouting pipe (3) is connected to the inside of the pulp bag (1). The pulp bag (1) is provided with a drainage network on the outside, and the drainage network is connected to the drainage pipe (4) through the upper partition (2) and the hole cover (7). The drainage pipe (4) is arranged on the hole cover (7). The lower end of the pulp bag (1) is provided with a bottom partition (601) or a pile shoe (602). A plurality of limit strips (5) are located on the outside of the pulp bag (1) and are hingedly arranged on the upper partition (2). A surrounding tube (9) is arranged on the upper partition (2).

2. A regular bottom-enlarged size capsule injection bag according to claim 1, characterized in that: The upper partition (2) is provided with a limit stopper (201) at a hinged position corresponding to the limit strip (5), and the side of the limit stopper (201) facing the limit strip (5) is an inclined surface.

3. A regular bottom-enlarged size capsule injection bag according to claim 1, characterized in that: The upper partition plate (2) is provided with a plurality of water holes (202) arranged radially, one end of the water hole (202) is connected to the drainage network, and the hole cover (7) is provided with an annular groove (701) at a position corresponding to the other end of the water hole (202), and the annular groove (701) is connected to the drainage pipe (4).

4. A regular bottom-enlarged size capsule injection bag according to claim 3, characterized in that: The drainage network comprises a plurality of drainage strips arranged circumferentially and longitudinally, and the upper ends of the drainage strips arranged longitudinally are connected to the water holes (202) of the upper partition plate (2).

5. A regular bottom-enlarged size capsule injection package according to claim 1, characterized in that: A pressure relief valve is arranged in the middle of the bottom diaphragm (601); and pressure relief valves are symmetrically arranged on both sides of the pile shoe (602).

6. A method for forming a capsule package with a regular bottom expansion size based on any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Determine the size of the enlarged head and the size of the injection bag: The size of the enlarged head should be designed according to the bearing capacity requirements of the foundation pile, and the compaction effect of the soil at the pile end should be considered; the length of the limit strip (5) is determined according to the size of the cone on the enlarged head, and the shape and size of the injection bag after it is fully expanded are determined according to the shape and size of the enlarged head; the size of the upper partition and the bottom partition or pile shoe is determined according to the pile diameter; Step 2: Determine the reserved space when the injection bag is sunk: Based on soil consolidation theory and engineering experience, estimate the maximum space size formed by the soil at the pile end under the compression of the proposed injection bag, and use the difference between the designed enlarged head volume and the maximum space as the size of the space to be occupied by the injection bag after it sinks to the bottom of the hole - that is, the reserved space; The shape of the reserved space of the capsule injection bag is a cylinder. The diameter D is the diameter of the inscribed circle of the circle surrounded by the limit bar hanging naturally. The height h is calculated by the following formula: Where V0 is the design value of the enlarged head volume, cm 3 ; V is the volume of space formed by the compaction of soil under bladder injection, cm 3 , take the strip load with a semi-infinite space width of h0 (the load value is the slurry pressure in the injection bag) and multiply the vertical compression of the soil by or The value of D0 is the diameter of the cylindrical section of the enlarged head; h0 is the total height of the enlarged head, which is the sum of the heights of the two frustum sections and the cylindrical section; D is the diameter of the reserved space of the capsule injection bag, which is the diameter of the inscribed circle formed by the naturally hanging limit strip (5); Step 3: Assemble the sac bag, limit the sac bag within the range surrounded by the limit strip (5) hanging naturally, symmetrically set Velcro drawstrings on the limit strip (5) in the height direction of the reserved space to hold the folded sac bag; remove the hole cover (7) and fill the slurry bag (1) with pebbles, and then install the hole cover to ensure the height and radial width of the reserved space; connect the drainage pipe and the grouting pipe; connect the conveying rod; Step 4: Drill the pile hole; Step 5: Overdrilling: When the space created by the injection-injection extrusion of soil is smaller than the volume of the pile bottom expansion, it is necessary to drill out the insufficient space, i.e. overdrilling. The overdrilling depth is h. 超 Estimated by the following formula: Where D 孔 is the drilling diameter; D is the diameter of the reserved space of the capsule injection bag; h is the height of the space reserved for the capsule injection bag; Step 6: Lowering the capsule injection bag: Slowly lower the capsule injection bag to the bottom of the hole through the conveying rod (8), and keep the conveying rod (8) centered; Step 7: Pour the pile body concrete, remove the delivery rod (8), and implement the bladder injection and bottom expansion after 7 to 28 days: (a) preparing slurry, cement: water: additive = 1: (0.5-0.7): 0.08, cement is PO52.5 ordinary Portland cement, and additive is UEA expansion agent; (b) connecting the grouting pipe (3) to the grouting pump; (c) intermittently injecting grout into the slurry bag (1) through the grouting pipe (3) to remove the air in the slurry bag (1); Then, continuous grouting is performed, and the slurry bag (1) stretches the Velcro rope during the opening process, and the slurry bag (1) squeezes the soil toward the bottom and sides, generating excess pore water pressure in the soil; as the water and / or gas in the soil passes through the drainage network on the outer surface of the slurry bag (1), it enters the upper partition (2) and is then discharged to the ground along the drainage pipe (4); Step 8: After the slurry in step 7 solidifies, fill the drain pipe (4) with the slurry; Step 9: Cut off the drainage pipe (4) and grouting pipe (3) at the top of the pile, and cut off the drainage pipe (4) and grouting pipe (3) along the pile head.

7. A method for regularly expanding the bottom size of injection molding according to claim 6, characterized in that: In step 7, when the limit strip (5) is fully opened and the grouting volume basically reaches the maximum design capacity of the bladder injection bag, the grouting pressure will rise sharply. At this time, the grouting is stopped and the grouting pressure is maintained for 2 to 6 hours, or until there is no water discharged from the drainage pipe (4). Then, the slurry is injected and the pressure is gradually increased. When the slurry in the slurry bag (1) exceeds a certain high pressure value, the slurry will be ejected from the pressure relief valve and the pile end soil and the periphery of the bladder injection bag will be compacted and split. This can be carried out several times to further strengthen the pile end soil. During the last injection, the drainage pipe is closed, and slurry that can solidify the cement slurry in a short time can be injected. When the slurry input volume is basically 0, the grouting pipe is closed.

8. A method for regularly expanding the bottom size of injection molding according to claim 7, characterized in that: If the grouting pressure reaches the design value but the grouting volume is far from the maximum design capacity of the capsule bag, close the grouting pipe and wait for 2 to 6 hours until the extremely high super-static pore water pressure in the soil around the capsule bag has dissipated significantly or even basically dissipated, then additional injection is performed to ultimately make the grouting volume reach the maximum design capacity of the capsule bag.

9. A method for injection molding with regular bottom expansion size according to claim 6, characterized in that: For reinforced concrete piles, lower the steel cage before pouring the pile concrete in step 7.

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