A method for reinforcing deep backfill foundation by deep grouting and steel pipe pile

Abstract

The present application belongs to the technical field of deep backfill soil reinforcement, and discloses a method for reinforcing deep backfill foundation by deep grouting and steel pipe pile, to solve the problem that the deep backfill soil below 9m cannot be reinforced by steel pipe pile because the load cannot be transmitted to the deep backfill soil below 9m by the steel pipe pile. The present application comprises (1) measuring and releasing wire to determine the position of pile hole; (2) positioning the drilling machine; (3) drilling by the drilling machine to form pile hole; (4) lowering the grouting pipe into the pile hole; (5) implanting the steel pipe pile into the pile hole; (6) filling the steel pipe pile with gravel; (7) pouring the lower pile hole through the grouting pipe; (8) pouring the steel pipe pile. The present application can reinforce the deep backfill soil at the lower part, solve the problem that the deep backfill soil at the lower part cannot be reinforced by the steel pipe pile, thereby ensuring that the backfill soil at each depth position of the deep backfill soil can be reinforced, and meeting the reinforcement requirement of the deep backfill foundation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of deep backfill soil reinforcement, and particularly relates to a method for reinforcing deep backfill foundation by deep grouting and steel pipe pile, which is used for reinforcing red layer high fill area. BACKGROUND

[0002] In recent years, the infrastructure construction of transportation, water conservancy, energy and power industries has gradually increased, and the shortage of land resources has become increasingly prominent. In order to solve the contradiction between the shortage of land resources and the rapid growth of engineering construction land, and in compliance with the relevant policies of the state for protecting basic farmland, the method of "mountain filling" and "sea reclamation" is used to obtain land from nature. The southwest region is mainly composed of plateau, mountain and hilly land. Due to the restriction of topographic and geomorphic conditions, more and more engineering construction sites need to use large excavation and large backfill, so the number and scale of deep backfill sites have increased significantly. Although backfill sites solve the problem of tight engineering construction land, deep backfill foundation has problems such as uneven backfill thickness, loose fill, and large compressibility, which is difficult to meet the requirements of engineering structure on foundation strength, deformation and stability. The specific adverse performance is as follows: (1) the source, backfill time, method, thickness and engineering environment of backfill soil are different, and the physical and mechanical properties of backfill soil (such as particle size composition, density, strength, compressibility and permeability) are unevenly distributed in space, which is easy to produce uneven settlement; (2) the backfill time is short, the soil body has large and many pores, and does not complete self-weight consolidation, showing high compressibility and strength much lower than that of natural deposited soil; (3) the deep backfill area has large backfill depth, long time for completing self-weight consolidation and large consolidation settlement.

[0003] Through the analysis of the above-mentioned properties of deep backfill soil, it can be known that the untreated backfill foundation has many engineering problems and cannot be directly used in engineering construction. Appropriate measures need to be taken to eliminate or reduce the foundation risk caused by the adverse engineering properties of backfill soil to ensure the safety of upper building (structure).

[0004] At present, deep backfill sites mainly use dynamic compaction treatment and pile forms. Dynamic compaction foundation treatment is suitable for shallow foundation reinforcement, and its effective reinforcement depth is related to many factors such as physical and mechanical parameters of backfill soil, engineering geological conditions and dynamic compaction energy level, and is usually not more than 10 meters, so it has poor applicability to deep backfill sites.

[0005] Rotary jet grouting pile and cement mixing pile are widely used in soft soil foundation reinforcement, and the design usually needs to pass through the backfill soil layer, which is poor in economy and environmental protection. Using pile foundation form as the foundation of deep backfill field, the foundation pile not only needs to pass through the backfill soil layer and embed into the bedrock to a certain depth, but also provides negative friction to the foundation pile during the consolidation settlement process of the untreated backfill soil, which increases the rock-embedding depth of the foundation pile, and the pile foundation can only solve the settlement problem of the upper structure, but cannot solve the settlement problem of the floor, especially some industrial parks with high settlement requirements.

[0006] The filling depth or height of deep backfill site or high fill foundation can reach dozens of meters. Although the use of steel pipe pile grouting can control the foundation settlement problem, the main disadvantage is that the verticality is difficult to control. Through relevant static load test research, it is found that the steel pipe pile is difficult to transfer the upper load to the steel pipe pile below 9m, therefore, the utilization rate of the steel pipe pile with a depth greater than 9m is low. And through research, it is also found that the main reason for the settlement of backfill soil below 9m (i.e. the thickness of backfill soil is greater than 9m) is self-weight consolidation settlement, i.e. the soil body under the action of self-weight, the porosity is low, and the pore water pressure disappears. SUMMARY

[0007] In order to solve the problem that the steel pipe pile cannot transfer the load to the deep backfill soil below 9m, resulting in the deep backfill soil below cannot be reinforced by the steel pipe pile, the present application provides a method for reinforcing deep backfill foundation by deep grouting and steel pipe pile, which can reinforce the deep backfill soil below, solve the problem that the steel pipe pile cannot reinforce the deep backfill soil below, and ensure that the backfill soil at each depth position of the deep backfill soil can be reinforced, thereby meeting the reinforcement demand of deep backfill foundation.

[0008] To solve the technical problem, the technical scheme adopted by the present application is:

[0009] A method for reinforcing deep backfill foundation by deep grouting and steel pipe pile, characterized in that it comprises the following steps:

[0010] (1) measuring and laying out to determine the position of the pile hole.

[0011] (2) positioning the drilling machine.

[0012] (3) drilling the drilling machine to form a pile hole, the pile hole comprising an upper pile hole and a lower pile hole, the size of the lower pile hole being smaller than that of the upper pile hole, the depth of the upper pile hole being not more than 9m, and the lower pile hole extending through the deep backfill soil and reaching the undisturbed soil.

[0013] (4) Lower the grouting pipe into the pile hole, the grouting pipe extends downward to the lower pile hole and is 300-500 mm away from the bottom of the lower pile hole, the outer periphery of the grouting pipe is sleeved with a partition plate, and the position of the partition plate on the grouting pipe corresponds to the position of the intersection surface of the upper pile hole and the lower pile hole; an annular groove is formed on the grouting pipe below the partition plate, a sleeve capable of sliding up and down in the annular groove is installed in the annular groove, a floating plate is installed on the top of the sleeve, and the outer diameter of the floating plate is matched with the inner diameter of the lower pile hole; a through hole is formed on the partition plate and the floating plate, and the through holes on the partition plate and the floating plate are staggered; the floating plate can shield the through holes on the partition plate corresponding to the area range of the lower pile hole.

[0014] (5) Implant the steel pipe pile into the pile hole, and the lower end of the steel pipe pile corresponds to the position of the intersection surface of the upper pile hole and the lower pile hole; that is, the lower end of the steel pipe pile corresponds to the position of the bottom of the upper pile hole.

[0015] (6) After the implantation of the steel pipe pile is completed, implant the return grouting pipe into the steel pipe pile, and the return grouting pipe is located in the interior of the steel pipe pile; fill the gravel into the steel pipe pile after the installation of the return grouting pipe.

[0016] (7) Perform the first pouring and the second pouring on the lower pile hole in sequence through the grouting pipe, the first pouring is pouring the lower pile hole by using the grouting pipe; the second pouring includes sleeving the pressurizing pipe into the grouting pipe, the outer periphery of the pressurizing pipe is sleeved with a sealing plate, the sealing plate and the inner wall of the grouting pipe are in sliding sealing with each other, and the pressurizing pipe extends downward to the lower part of the sleeve and performs pressurized grouting on the lower pile hole.

[0017] (8) Pull out the pressurizing pipe in the grouting pipe, seal the top of the steel pipe pile, and pour the steel pipe pile (i.e., pour the upper pile hole) by using the grouting pipe after the sealing treatment is completed.

[0018] In some embodiments, when the first pouring is performed on the lower pile hole, the grouting is first performed along the inner wall of the grouting pipe to form a grouting curtain on the grouting pipe, and then the grouting is performed by using the middle part of the grouting pipe.

[0019] In some embodiments, when the first pouring is performed on the lower pile hole and the pouring (i.e., pouring the steel pipe pile) is performed on the upper pile hole, the pouring should be segmented; the length of each segment is 2.0-3.0 meters. The intermittent time between segments is preferably 2 hours.

[0020] In some embodiments, the grouting is supplemented after the pouring of the steel pipe pile is completed. The grouting surface will shrink in different situations during the static and solidification period after the pouring of the steel pipe pile is completed, so the grouting operation must be performed to ensure the grouting quality (effect), and the grouting pump is used to directly deliver the grout into the hole or the return grouting pipe is used to pressurize the grout into the hole.

[0021] In some embodiments, the partition plate is connected with a steel bar, and the steel bar on the partition plate can be inserted into the lower pile hole, a through hole is formed on the floating plate corresponding to the position of the steel bar, and a sealing ring is arranged in the through hole.

[0022] In some embodiments, the partition plate is fixedly connected to the lower end of the steel pipe pile.

[0023] In some embodiments, the partition plate is provided with a positioning groove, and a positioning block is arranged on the grouting pipe corresponding to the position of the positioning groove.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile of the present application uses steel pipe pile to grout and reinforce the upper area of deep backfill soil (i.e., the backfill soil within 9m from the ground), and then uses the grouting reinforcement technology to reinforce the lower area of deep backfill soil (i.e., the backfill soil outside 9m from the ground). On the one hand, it solves the problem of serious waste of super-long steel pipe pile (length exceeding 10m) caused by the fact that the steel pipe pile cannot transmit load to the soil below 9m from the ground, and solves the problems of implantation and verticality adjustment of super-long steel pipe pile; on the other hand, the present application can fully utilize the lower area of deep backfill soil for grouting reinforcement, thereby extruding and compacting the lower area of deep backfill soil (i.e., the backfill soil below 9m from the ground), so that the settlement of deep backfill soil meets the requirements; and the consolidation body poured in the lower pile hole together with the steel pipe pile bears the load, transmits the load to the consolidation body formed in the lower pile hole, and disperses the load to the deep backfill soil below 9m, thereby improving the bearing capacity of deep backfill foundation and steel pipe pile. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The structure schematic diagram after pouring of the present application is shown in the figure;

[0027] Figure 2 The transverse sectional schematic diagram of the upper pile hole after pouring of the present application is shown in the figure;

[0028] Figure 3 The transverse sectional schematic diagram of the lower pile hole after pouring of the present application is shown in the figure;

[0029] Figure 4 The structure schematic diagram when the lower pile hole is poured for the first time of the present application is shown in the figure, and there is a spacing between the partition plate and the floating plate;

[0030] Figure 5 The structure schematic diagram when the lower pile hole is poured for the second time of the present application is shown in the figure, and the partition plate and the floating plate are in close contact with each other when the lower pile hole is pressurized and grouted by using the pressurizing pipe;

[0031] Marked in the figure: 01, deep backfill, 02, undisturbed soil, 1, pile hole, 11, upper pile hole, 12, lower pile hole, 2, steel pipe pile, 3, grouting pipe, 31, positioning block, 4, stone, 5, partition plate, 51, through hole, 52, positioning groove, 6, sleeve, 7, floating plate, 8, pressurizing pipe, 9, sealing plate. DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with the embodiments. The described embodiments are only a part of the embodiments of the application, and not all the embodiments. Based on the embodiments in the application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0033] In the description of the application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application; the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0034] In conjunction with the drawings, the method for reinforcing deep backfill foundation by using deep grouting and steel pipe pile of the application comprises the following steps:

[0035] (1) Measure the line to determine the position of the pile hole.

[0036] (2) Position the drilling machine, adjust the drilling machine to ensure that the center of the drill rod, the center of the drill bit and the center of the pile hole are on the same straight line. After the drilling machine is installed in place, measures are taken to stabilize it to ensure that the drilling machine does not deviate or tilt during operation.

[0037] (3) The drilling machine drills into the hole to form the pile hole 1, which includes the upper pile hole 11 and the lower pile hole 2, the size of the lower pile hole 12 is smaller than that of the upper pile hole 11, the depth of the upper pile hole 11 does not exceed 9m, and the lower pile hole 12 extends through the deep backfill 01 and into the undisturbed soil 02. In the specific implementation process, the lower pile hole 12 extends at least 0.3m-0.5m below the undisturbed soil 02.

[0038] In the specific implementation process, if the deep backfill soil 01 has other good quality fillers (for example, A-grade fillers, B-grade fillers) below, the lower pile hole can also be diffracted into the good quality fillers. For example: A-grade is high-quality filler, such as coarse-grained cohesionless soil. B-grade is good filler, such as mixed soil with less than 30% fine particles and sandy clay, etc. C-grade is a limited-use filler, such as mixed soil with more than 30% fine particles and silt, etc. For good quality fillers, those skilled in the art will understand and understand without further description.

[0039] (4) Lower the grouting pipe 3 into the pile hole 1, the grouting pipe 3 extends downward to the lower pile hole 12 and is 300-500mm away from the bottom of the lower pile hole 12, the outer periphery of the grouting pipe 3 is sleeved with a partition plate 5, and the position of the partition plate 5 on the grouting pipe 3 corresponds to the intersection position of the upper pile hole 11 and the lower pile hole 12; an annular groove is formed on the grouting pipe 3 below the partition plate 5, a sleeve 6 capable of sliding up and down in the annular groove is installed in the annular groove, a floating plate 7 is installed on the top of the sleeve 6, the outer diameter of the floating plate 7 is matched with the inner diameter of the lower pile hole 12, and a through hole 51 is formed on the partition plate 5 and the floating plate 7. The through holes 51 on the partition plate 5 and the floating plate 7 are staggered, and the floating plate 7 can shield the through holes 51 on the partition plate 51 in the area range corresponding to the lower pile hole 12. The through holes 51 on the partition plate 5 and the floating plate 7 are used to ensure the flow between the slurry above and below the partition plate. When the lower pile hole 12 is grouted by the grouting pipe 3, the through hole 51 can play a role in exhaust and back slurry, and the floating plate 7 and the sleeve 6 are located at the lower end of the annular groove under the action of gravity, so that the upper end surface of the floating plate 7 and the lower end surface of the partition plate 5 have a spacing, so that the through holes 51 on the partition plate 5 and the floating plate 7 can be connected to exhaust and back slurry.

[0040] When pressure grouting is performed by using the pressurizing pipe 8, the floating plate 7 is driven upward by the cement slurry pressure to overcome the weight of the floating plate and the sleeve, so that the floating plate 7 and the partition plate 5 are in contact with each other, and the through holes 51 are in a state of being unable to be connected, thereby realizing the pressure grouting operation of the lower pile hole 12.

[0041] (5) Implanting a steel pipe pile 2 into the pile hole 1, the lower end of the steel pipe pile 2 corresponds to the intersection position of the upper pile hole 11 and the lower pile hole 12; that is, the lower end of the steel pipe pile 2 corresponds to the bottom position of the upper pile hole 11. In order to facilitate the extension of the grouting pipe 3 into the lower pile hole 12, and also facilitate the installation of the partition plate 5, the lower end of the steel pipe pile 2 does not have a sharp end. The grouting pipe 3 is located in the inside of the steel pipe pile 2, which can be understood by those skilled in the art.

[0042] The verticality of the implanted steel pipe pile should meet the requirements. In the specific implementation process, when the length of the steel pipe pile is long (i.e. when the length of the steel pipe pile exceeds 10 m, with the increase of the length, the pile hole is more or less inclined and offset, so for the steel pipe pile with long length, the implantation and verticality adjustment of the steel pipe pile are a very time-consuming work), the difficulty of adjusting the verticality of the steel pipe pile is very great, and in the adjustment process, the steel pipe pile is easily bent, thereby causing the bearing capacity and bending resistance of the steel pipe pile after pouring to greatly decrease. Therefore, for the construction of the steel pipe pile, the main difficulty lies in the adjustment of the verticality of the steel pipe pile. Especially for the steel pipe pile with long length (the length exceeds 10 m), the verticality adjustment is very difficult and costs high time cost.

[0043] (6) After the implantation of the steel pipe pile 2 is completed, a return slurry pipe is implanted into the steel pipe pile 2, the return slurry pipe is located in the inside of the steel pipe pile; after the return slurry pipe is installed, the gravel 4 is filled into the steel pipe pile. The particle size of the gravel can be determined according to the inner diameter of the steel pipe pile 2, which can be understood by those skilled in the art. Generally, the maximum particle size of the gravel 4 does not exceed 15 mm.

[0044] (7) The first pouring and the second pouring are sequentially performed on the lower pile hole 12 through the grouting pipe 3, the first pouring is to pour the lower pile hole 12 by using the grouting pipe 3; the second pouring includes sleeving the pressurizing pipe 8 into the grouting pipe 3, the pressurizing pipe 8 is peripherally sleeved with the sealing plate 9, the sealing plate 9 and the inner wall of the grouting pipe 3 are mutually sealed by sliding, and the pressurizing pipe 8 extends downward to below the sleeve 6 and pressurizes and grouts the lower pile hole 12. The pressurizing pipe 8 can pressurize and grout the lower pile hole according to the present application, so that more cement slurry can enter the rock-soil body, thereby improving the bearing capacity of the deep backfill soil. However, in the prior art, it is difficult to transmit the load to the area below 9 m due to the bearing capacity transmission of the steel pipe pile, therefore, the present application reinforces the lower part of the steel pipe pile by grouting, thereby reinforcing the deep backfill soil below 9 m, and the deep backfill soil below 9 m is fully utilized to bear the load by pouring the lower pile hole, therefore, the present application can improve the bearing capacity of the deep backfill soil from two aspects. One is that the deep backfill soil below 9 m is grouted and reinforced, so that the deep backfill soil below 9 m and the consolidated body formed by pouring the lower pile hole form an integral whole, the settlement of the deep backfill soil is reduced to meet the settlement requirement; the other is that the consolidated body poured by the lower pile hole bears the load together with the steel pipe pile, the load is transmitted to the consolidated body formed in the lower pile hole and dispersed to the deep backfill soil below 9 m, thereby improving the bearing capacity of the steel pipe pile.

[0045] The length of the steel pipe pile 2 is not more than 9 m, so the steel pipe pile is convenient to implant and vertically adjust, and the efficiency of implanting and vertically adjusting the steel pipe pile is greatly improved. The problem that the verticality of the super-long steel pipe pile (the length is more than 10 m) is difficult to adjust in the prior art is solved. Meanwhile, the length of the steel pipe pile is not more than 9 m, so the steel pipe pile will not be bent when the verticality is adjusted, and the problems of the compression strength and the bending capacity being reduced due to the bending of the steel pipe pile are prevented.

[0046] In summary, the method for reinforcing the deep backfill foundation by deep grouting and steel pipe pile in the application is used to grout and reinforce the upper area of the deep backfill soil (that is, the backfill soil within 9 m from the ground), and then the lower area of the deep backfill soil (that is, the backfill soil outside 9 m from the ground) is reinforced by the grouting reinforcement technology. On the one hand, the problem that the super-long steel pipe pile (the length is more than 10 m) is seriously wasted due to the fact that the load cannot be transmitted to the soil below 9 m from the ground by the steel pipe pile is solved, and the problems of implanting and vertically adjusting the super-long steel pipe pile are solved. On the other hand, the lower area of the deep backfill soil is fully utilized to grout and reinforce, and then the lower area of the deep backfill soil (that is, the backfill soil below 9 m from the ground) is extruded and compacted, so that the settlement of the deep backfill soil meets the requirements. The load is transmitted to the consolidated body formed in the lower pile hole and dispersed to the deep backfill soil below 9 m from the ground by the consolidated body poured by the lower pile hole and the steel pipe pile together, so that the bearing capacity of the deep backfill foundation and the steel pipe pile is improved.

[0047] In the application, when the lower pile hole is poured for the first time, the cement slurry can flow through the through holes of the partition plate and the floating plate, when the lower pile hole is poured for the second time by pressure grouting, the sleeve and the floating plate can be driven to move upward along the grouting pipe under the action of the strong pressure of the cement slurry, and then the through holes on the partition plate are shielded by the floating plate, so that the pressure grouting of the lower pile hole is ensured. When the cement slurry is poured for the first time, the cement slurry can enter the upper part of the partition plate through the through holes, which can play the roles of exhausting and returning of the slurry when the lower pile hole is poured. Meanwhile, the cement slurry can also consolidate the upper pile hole and the lower pile hole into a whole, so that the steel pipe pile poured in the upper part and the consolidated body poured in the lower part form a complete whole, and the bearing capacity is further improved.

[0048] In some embodiments, when the lower pile hole 11 is poured for the first time, the cement slurry is poured along the inner wall of the grouting pipe 3 to form a grouting curtain on the grouting pipe 3, and then the cement slurry is poured in the middle of the grouting pipe 3. The purpose of pouring the cement slurry along the inner wall of the grouting pipe first is to form a grouting curtain on the grouting pipe, so that the cement slurry is prevented from exuding outward and the quality of pouring the lower pile hole for the first time is improved.

[0049] (8) pull out the pressurized pipe 8 in the grouting pipe 3, and seal the top of the steel pipe pile 2. After the sealing process is completed, the steel pipe pile is poured using the grouting pipe 3 (i.e., the upper pile hole is poured).

[0050] In the specific implementation process, the top of the steel pipe pile 2 can be sealed by using cement slurry. After the cement slurry sealing process reaches the design strength, the steel pipe pile 2 can be poured.

[0051] When grouting and pouring the lower pile hole and the upper pile hole (i.e., pouring the steel pipe pile), the following steps are mainly included: grouting equipment connection, slurry preparation, pure cement slurry is used for grouting, the type, grade, fineness modulus, and water-cement ratio of the cement should meet the design requirements, the grouting cement must meet the quality standards and should be kept fresh, and cement that is damp or clumped should not be used. The materials for preparing the slurry must be weighed before preparation, the stirring time of the slurry should be no less than 3 minutes when using a general stirrer and no less than 30 seconds when using a high-speed stirrer, and the time from preparation to use should be less than 4 hours. The temperature of the slurry should be kept at 5-40°C. Therefore, the grouting operation (including the first pouring and the second pouring of the lower pile hole, and the pouring of the upper pile hole (i.e., pouring the steel pipe pile)) belongs to the prior art, and will not be described here.

[0052] In some embodiments, when the lower pile hole 12 is poured for the first time and the upper pile hole 11 is poured (i.e., the steel pipe pile is poured), the pouring should be segmented; the length of each segment should be 2.0-3.0 meters. The intermittent time between segments should be 2 hours.

[0053] In some embodiments, after the steel pipe pile 2 is poured, supplementary grouting is performed as needed. After the steel pipe pile 2 is poured, the slurry surface may shrink in different ways during the static and solidification period, so supplementary grouting operation must be performed to ensure the grouting quality (effect). The grouting pump is used to directly pump slurry into the hole or the return slurry pipe is used to pressurize the supplementary grouting into the hole.

[0054] In some embodiments, the partition plate 5 is connected with a planted bar, and the planted bar on the partition plate 5 can penetrate into the lower pile hole 12. A through hole is formed on the floating plate 7 corresponding to the position of the planted bar, and a sealing ring is arranged in the through hole. Through the design of the planted bar, the connection strength between the lower pile hole and the upper pile hole can be further improved, so that the load of the steel pipe pile 2 can be smoothly transmitted to the consolidated body in the lower pile hole, so as to achieve the purpose of improving the bearing capacity.

[0055] In some embodiments, the partition plate 5 is fixedly connected to the lower end of the steel pipe pile 2. In specific implementation, the partition plate 5 is provided with a through hole for the grouting pipe 3 to pass through, so that the grouting pipe 3 can pass out of the partition plate 5 and extend into the lower pile hole 12.

[0056] In specific implementation, preferably, the outer diameter of the partition plate 5 is slightly larger than the outer diameter of the steel pipe pile 2 and smaller than the inner diameter of the upper pile hole 11, so that the steel pipe pile 2 can uniformly transmit the load to the partition plate 5 when bearing the load, the partition plate 5 directly transmits part of the load to the stepped surface formed by the upper pile hole 11 and the lower pile hole 12 and then directly transmits the load to the corresponding deep backfill soil 01 of the lower pile hole to bear the load, and at the same time, the partition plate 5 directly transmits part of the load to the consolidated body formed by pouring the lower pile hole 12, so that the corresponding deep backfill soil of the lower pile hole 12 and the consolidated body formed by pouring can jointly bear the load to improve the bearing capacity.

[0057] In some embodiments, the partition plate 5 is provided with a positioning groove 52, and the grouting pipe 3 is provided with a positioning block 31 corresponding to the position of the positioning groove 52, and the positioning block 31 and the positioning groove 52 are matched with each other to position the grouting pipe 3 on the partition plate 5, so as to realize the installation and positioning of the grouting pipe 3. Therefore, the grouting pipe can be directly positioned by the partition plate during use, the number of centering supports can be reduced or even not set, and the processing workload of the grouting pipe is further reduced.

[0058] In specific implementation, when pouring the lower pile hole, the partition plate can position the grouting pipe; when pouring the upper pile hole, the lower part of the grouting pipe has been poured, that is, the lower part of the grouting pipe is embedded in the cement slurry in the lower pile hole, so as to further improve the stability of the grouting pipe. Therefore, compared with the prior art, the centering supports do not need to be set on the periphery of the grouting pipe, so that the workload is reduced.

[0059] Since the centering supports are generally uniformly distributed on the periphery of the grouting pipe, the heights of the centering supports extending out of the grouting pipe need to be matched with each other during installation, and the centering supports are generally fixed on the periphery of the grouting pipe by welding, so that the grouting pipe has the problem of large workload during fixing the centering supports. The present application can reduce or even eliminate the installation of the centering supports, so as to reduce the workload.

Claims

1. A method for reinforcing a deep backfill foundation by deep grouting and steel pipe pile, characterized in that, The method comprises the following steps: (1) measuring and determining the position of the pile hole; (2) positioning the drilling machine; (3) drilling the pile hole (1) by the drilling machine, wherein the pile hole (1) comprises an upper pile hole (11) and a lower pile hole (12), the size of the lower pile hole (12) is smaller than that of the upper pile hole (11), the depth of the upper pile hole (11) is not more than 9 m, and the lower pile hole (12) penetrates through the deep backfill soil (01) and extends to the undisturbed soil (02); (4) lowering the grouting pipe (3) into the pile hole (1), wherein the grouting pipe (3) extends downward to the lower pile hole (12) and is 300-500 mm away from the bottom of the lower pile hole, the outer periphery of the grouting pipe (3) is sleeved with a partition plate (5), and the position of the partition plate (5) on the grouting pipe (3) corresponds to the position of the intersection of the upper pile hole (11) and the lower pile hole (12); an annular groove is formed on the grouting pipe (3) below the partition plate (5), a sleeve (6) capable of sliding up and down in the annular groove is installed in the annular groove, a floating plate (7) is installed on the top of the sleeve (6), and the outer diameter of the floating plate (7) is matched with the inner diameter of the lower pile hole (12); a through hole (51) is formed on the partition plate (5) and the floating plate (7), the through holes (51) on the partition plate (5) and the floating plate (7) are staggered; the floating plate (7) can shield the through holes (51) on the partition plate (5) in the area corresponding to the lower pile hole (12); (5) implanting the steel pipe pile (2) into the pile hole (1), wherein the lower end of the steel pipe pile (2) corresponds to the position of the intersection of the upper pile hole (11) and the lower pile hole (12); (6) after the implantation of the steel pipe pile (2) is completed, implanting the return grouting pipe into the steel pipe pile, wherein the return grouting pipe is located in the interior of the steel pipe pile; after the installation of the return grouting pipe, filling the gravel (4) into the steel pipe pile (2); (7) sequentially performing the first pouring and the second pouring on the lower pile hole (12) through the grouting pipe (3), wherein the first pouring is performed by pouring the grouting pipe on the lower pile hole; the second pouring comprises sleeving the pressurizing pipe (8) into the grouting pipe (3), the outer periphery of the pressurizing pipe (8) is sleeved with a sealing plate (9), the sealing plate (9) and the inner wall of the grouting pipe (3) are in sliding sealing, the pressurizing pipe (8) extends downward to the lower side of the sleeve (6) and performs pressurized grouting on the lower pile hole (12); (8) pulling out the pressurizing pipe (8) in the grouting pipe (3), sealing the top of the steel pipe pile (2), and pouring the steel pipe pile (2) by using the grouting pipe (3) after the sealing treatment is completed.

2. The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile according to claim 1, characterized in that, When the first pouring is performed on the lower pile hole (12), the pouring is first performed along the inner wall of the grouting pipe to form a grouting curtain on the grouting pipe, and then the middle part of the grouting pipe (3) is used for pouring.

3. The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile according to claim 1, characterized in that, When the first pouring is performed on the lower pile hole (12) and the pouring is performed on the upper pile hole (11), the pouring should be performed in sections, and the length of each section is 2.0-3.0 m.

4. The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile according to claim 1, characterized in that, After the pouring of the steel pipe pile (2) is completed, the grouting is supplemented according to the needs.

5. The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile according to any one of claims 1-4, characterized in that, The partition plate (5) is connected with a planted steel bar, and the planted steel bar on the partition plate (5) can penetrate into the lower pile hole (12).

6. The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile according to claim 5, characterized in that, The partition plate (5) is fixedly connected to the lower end of the steel pipe pile (2).

7. The method for reinforcing deep backfill foundation by deep grouting and steel pipe pile according to claim 5, characterized in that, The partition plate (5) is provided with a positioning groove (52), and the grouting pipe (3) is provided with a positioning block (31) corresponding to the position of the positioning groove (52).

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