Gate pump engineering foundation treatment structure

Abstract

The utility model relates to the technical field of gate pump engineering foundation construction, in particular to a gate pump engineering foundation treatment structure which comprises a bulk mixing pile, a fence type mixing pile and a conjoined mixing pile which are arranged in a deep soft soil layer, and prefabricated pipe piles are further arranged among the bulk mixing pile, the fence type mixing pile and the conjoined mixing pile. Cast-in-place pile and row pile retaining walls are arranged on the outer sides of the bulk mixing piles, the fence type mixing piles and the conjoined mixing piles, the bottoms of the bulk mixing piles, the fence type mixing piles and the conjoined mixing piles are arranged in a weathered layer, and the tops of the bulk mixing piles, the fence type mixing piles and the conjoined mixing piles form a construction platform through backfilling. Compared with foundation treatment schemes such as single cast-in-situ bored piles, vacuum-surcharge preloading, prefabricated concrete pipe piles or stirring piles, the composite foundation adopting the prefabricated pipe piles to rigidly combine with the grid-shaped or scattered point type stirring piles not only can meet the foundation treatment performance, but also has higher cost performance.

Description

Technical Field

[0001] The utility model relates to the technical field of gate pump engineering foundation construction, in particular to a gate pump engineering foundation treatment structure. Background Art

[0002] In recent years, with the development of construction technology and construction conditions in water conservancy projects, cement mixing piles have been applied more and more widely. In addition to being used as a composite foundation, they are also promoted as an economical foundation pit retaining structure. Designing and constructing the foundation pit retaining structure and the protection of the foundation pit and surrounding environment as a unified whole and strictly controlling and coordinating the implementation process can not only ensure the safety of the foundation pit and the surrounding environment, but also reduce the project cost and shorten the construction period.

[0003] For deep silt foundations, commonly used foundation treatment solutions include: bored cast-in-place piles, precast concrete pipe piles and mixing piles and other composite foundation treatment solutions. Among them, the bored cast-in-place pile solution, precast concrete pipe pile solution and cement mixing pile solution are mainly compared:

[0004] Advantages of bored piles: Since the pile foundation reaches the bearing layer, the settlement of the pump station is small, and settlement, especially uneven settlement, can be avoided. The construction equipment is relatively light. For construction on silt, the cushion layer of the construction platform to be filled is thin, and the movement of the pile driver has little impact on the constructed piles. The quality of the piles is easier to control and the quality is more guaranteed; the construction period is easy to control, and the construction progress can be adjusted by increasing or decreasing the pile driver. The riprap layer can be cleared in combination with the full-rotation full-casing drilling rig. Disadvantages: Since the load of the pump station is entirely borne by the pile foundation, the settlement of the sluice gate is not coordinated with the settlement of the foundation, which may cause the bottom plate of the pump station to be emptied from the foundation, and the anti-seepage requirements of the pump station are increased. In addition, when encountering plastic silt during construction, it is difficult to form holes, and steel casings need to be added, which increases construction costs.

[0005] Prefabricated pipe piles have the advantages of convenient construction, fast construction progress, small settlement and moderate cost. The first disadvantage is that the construction equipment is relatively heavy, which may cause displacement of the constructed piles during construction; the second is that prefabricated pipe piles are soil-squeezing piles. In highly saturated fluidized soft soil, the piles driven first will be squeezed out by the piles driven later, affecting the bearing capacity of the pile foundation. In addition, like bored cast-in-place piles, the settlement of the sluice is small. When the foundation settles, the gate chamber cannot settle with the foundation, which will cause the gate bottom to be emptied and cause contact scouring, so the requirements for anti-seepage are relatively high.

[0006] The construction equipment of cement mixing piles is simple, the project cost is relatively low, and the ability to adapt to foundation deformation is strong. However, for under-consolidated soft soil, the consolidation settlement of the soil between piles after deep mixing pile treatment is still difficult to solve, and a composite foundation cannot be formed. The treatment effect is not very good, and the post-construction settlement after treatment is still large. According to calculations, the settlement of this project is large, and it is difficult to control the uneven settlement between different structures. The pump station unit and the hoist gate are not sensitive to uneven settlement. The soft soil bottom of this project is buried deeper than 15m, the pile end of the mixing pile cannot enter the relatively hard layer, and the plasticity index of some soft soils is greater than 22. In addition, the gravel sand layer may liquefy under the action of an earthquake, and other engineering measures need to be taken to reduce the impact of sand layer liquefaction during the earthquake on the bearing capacity of the composite foundation.

[0007] Vacuum-loading preloading bagged sand wells or plastic drainage belt drainage consolidation method for soft foundation treatment has a low cost and belongs to the type of thorough reinforcement of foundation soil. The treatment effect is good, but the construction period is relatively long. Considering factors such as flood control during the flood season, it can only be arranged to use the vacuum preloading method for 3 months behind the embankment before the excavation of the foundation pit. According to calculations, the shear strength of the foundation soil after treatment is 26% to 40% higher than that before treatment. It is still necessary to cooperate with other engineering measures to further treat the foundation to improve the bearing capacity of the foundation.

[0008] Through the above calculations and comparisons, it is found that the bearing capacity of the foundation cannot meet the design requirements when using either the mixing pile scheme or the preloading method alone. In order to meet the horizontal resistance, a large number of prefabricated pipe piles or cast-in-place piles need to be arranged. The composite foundation scheme is more economical than the rigid connection scheme. Compared with the rigid composite foundation of cast-in-place piles and prefabricated pipe piles, the composite foundation of prefabricated pipe piles is more economical. Utility Model Content

[0009] The purpose of the utility model is to provide a foundation treatment structure for a gate pump project, which is used to select the most economical solution under the premise of satisfying the foundation performance, and use prestressed concrete pipe piles and cement soil mixing piles to reinforce the foundation, wherein the mixing piles play the role of foundation reinforcement, enclosure and water stopping, and foundation pit support, so as to solve the problems raised in the above-mentioned background technology.

[0010] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0011] A foundation treatment structure for a sluice pump project is used to optimize the existing foundation treatment scheme for a sluice pump project, and comprises a bulk mixing pile, a fence type mixing pile and a coupled mixing pile arranged in a deep soft soil layer, prefabricated pipe piles are arranged between the bulk mixing piles, the fence type mixing piles and the coupled mixing piles, a bored pile row retaining wall is arranged on the outside of the bulk mixing piles, the fence type mixing piles and the coupled mixing piles, a weathering layer is placed in the bottom of the bulk mixing piles, the fence type mixing piles and the coupled mixing piles, a construction platform is formed on the top by backfilling soil, a crushed stone cushion layer is laid on the construction platform, and a turf slope protection is arranged on the top of the construction platform and above the crushed stone cushion layer.

[0012] As a preferred solution of the utility model, the bulk mixing piles, fence-type mixing piles and combined mixing piles are filled with silty soil, clay and medium-coarse sand, and the weathered layer is weathered granite.

[0013] As a preferred solution of the utility model, the prefabricated pipe piles adopt 500AB100 type prestressed concrete pipe piles, and the mechanical performance index requirements are that the outer diameter of the pile body is>500mm and the anti-cracking bending moment is>121kNXm.

[0014] As a preferred solution of the utility model, the weathering layer includes a strongly weathered layer and a medium weathered layer, and the pile ends of the cast-in-place piles formed by the bulk mixing piles, fence-type mixing piles and combined mixing piles penetrate into the strongly weathered layer or the medium weathered layer by 2m, and the vertical bearing capacity of a single pile is not less than 1200kN.

[0015] As a preferred solution of the utility model, the bulk mixing piles, fence type mixing piles and combined mixing piles are further reinforced by reinforcing materials, and the reinforcing materials are ordinary cement with a strength grade of not less than 42.5 MPa.

[0016] As a preferred solution of the utility model, a construction joint is formed between each section of concrete in the bulk mixing piles, fence type mixing piles and combined mixing piles.

[0017] Beneficial effect: In view of the problems raised in the prior art, the utility model adopts a composite foundation of prefabricated pipe piles in combination with grid-shaped or scattered-point mixing piles. For construction sites located in deltaic marine-continental interphase sedimentary landforms, where the foundations are mostly thick layers of silt, the foundation pit can effectively support the slopes and prevent the foundation pit from rising. While meeting the requirements of bearing capacity, stability, deformation, resistance to liquefaction and reliability, the utility model also has the advantage of low cost. On the premise of meeting the foundation treatment performance, compared with the use of a single bored cast-in-place pile, vacuum-load preloading, prefabricated concrete pipe piles or mixing piles and other foundation treatment solutions, the use of a composite foundation of prefabricated pipe piles in combination with grid-shaped or scattered-point mixing piles can not only meet the foundation treatment performance, but is also more cost-effective and very practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a basic treatment plan layout diagram of a foundation treatment structure for a sluice pump engineering project of the utility model;

[0019] Figure 2 This is a cross-sectional view of a foundation treatment structure for a sluice pump project of the utility model;

[0020] Figure 3 This is a cross-sectional excavation diagram of a foundation treatment structure for a sluice pump project of the utility model.

[0021] In the figure: 1. Thick soft soil layer; 2. Bulk mixing piles; 3. Fence-type mixing piles; 4. Combined mixing piles; 5. Prefabricated pipe piles; 6. Cast-in-place piles; 7. Weathered layer; 8. Backfill soil; 9. Construction platform; 10. Turf slope protection. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0023] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant literature, and several embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0024] It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this article includes any and all combinations of one or more related listed items.

[0026] See also Figure 1-3, the utility model provides a technical solution:

[0027] A gate pump engineering foundation treatment structure is used to optimize the existing gate pump engineering foundation treatment scheme, which includes a bulk mixing pile 2, a fence type mixing pile 3 and a joint mixing pile 4 arranged in a deep soft soil layer 1, and a prefabricated pipe pile 5 is arranged between the bulk mixing pile 2, the fence type mixing pile 3 and the joint mixing pile 4. A cast-in-place pile retaining wall 6 is arranged outside the bulk mixing pile 2, the fence type mixing pile 3 and the joint mixing pile 4. A weathering layer 7 is placed at the bottom of the bulk mixing pile 2, the fence type mixing pile 3 and the joint mixing pile 4, and a construction platform 9 is formed on the top by backfilling soil 8. The backfilling soil 8 is collected from a soil material yard or purchased soil, and the clay content is preferably 10%~35%, the plasticity index is preferably 7~20, and the permeability coefficient K≤10 cm / s; it must not contain impurities such as plant roots, brick and tile garbage; the allowable deviation between the moisture content of the filling soil and the optimal moisture content is ±3%. A crushed stone cushion layer is laid on the construction platform 9. The crushed stone cushion layer is required to have a good gradation (crushed stone particle size 20-40mm). It is leveled and rolled after laying, and the relative density is required to be not less than 0.65. A turf slope protection 10 is provided on the top of the construction platform 9 and above the crushed stone cushion layer.

[0028] Specifically, the space between the bulk mixing pile 2, the fence type mixing pile 3 and the combined mixing pile 4 is filled with muddy soil, clay and medium coarse sand, wherein the medium coarse sand is required to be clean medium coarse sand, with an organic matter content of no more than 1%, no clay blocks and other debris, a mud content of no more than 5%, and a permeability coefficient of no less than 5x10 cm / s, the dry density should be not less than 17kN / m, and the weathering layer 7 is weathered granite; the prefabricated pipe pile 5 adopts 500AB100 type prestressed concrete pipe pile, and its mechanical performance index requirements are that the outer diameter of the pile body is>500mm, and the anti-cracking bending moment is>121kNXm; the weathering layer 7 includes a strong weathering layer and a medium weathering layer, and the pile end formed by the bulk mixing pile 2, the fence type mixing pile 3 and the joint mixing pile 4 enters the strong weathering layer or the medium weathering layer by 2m, and the vertical bearing capacity of a single pile is not less than 1200kN; the bulk mixing pile 2, the fence type mixing pile 3 and the joint mixing pile 4 are also reinforced by reinforcement materials, and the reinforcement material is ordinary cement with a strength grade of not less than 42.5MPa; construction joints are formed between each section of concrete in the bulk mixing pile 2, the fence type mixing pile 3 and the joint mixing pile 4;

[0029] The construction quality of the bulk mixing pile 2, fence type mixing pile 3 and combined mixing pile 4 shall meet the requirements of the following table:

[0030]

[0031] Among them, within 3 days after the pile is formed, the strength test of the pile should be carried out with a portable penetration instrument (N10). The strength of the pile body should be judged by the comparison method based on the number of portable penetration hits (N10). There are 2 points for one pile, and the penetration point should be at 1 / 4 of the pile diameter. The inspection frequency should be no less than 1% of the number of engineering piles. For areas with complex geological conditions or construction failures, the supervisor may increase the number of piles to be inspected according to the specific situation.

[0032] Specifically, in deep soft soil areas, consider using flexible piles such as mixing piles to reinforce the soft soil layer, improve the bearing capacity and horizontal resistance of the soft soil layer foundation, and regard the soft soil layer with higher bearing capacity after reinforcement as a soil layer with higher natural bearing capacity, and design it according to the theory of composite foundation of rigid piles such as prefabricated pipe piles, which is a rigid-flexible composite pile foundation. The rigid-flexible composite pile foundation has the advantages of rigid pile composite foundation: large bearing capacity, good adaptability to the upper structure of the building, and easy control of settlement and differential settlement; on the other hand, cement mixing piles can effectively improve the physical and mechanical properties of the upper soil, greatly improving the combined force of pile-soil action.

[0033] In engineering practice, the mixed pile composite foundation is mostly composed of independent single piles and foundation soil, which is called scattered mixed pile composite foundation; while the mixed piles are overlapped vertically and horizontally to form a grid-like or strip-like continuous wall. The composite foundation composed of the grid wall and the soil columns divided by the grid wall is called a grid-like mixed pile composite foundation.

[0034] Scattered mixing piles are often used in soft clay or silt foundations with a bearing capacity of no more than 120kPa, such as silt and silty soil, to solve the bearing capacity, stability and deformation problems; while fence-shaped mixing piles are used in the above strata, which are more likely to meet the requirements of projects with high load levels and strict settlement requirements on the foundation. In addition, fence-shaped mixing piles are often used in loose-slightly dense sand or silt foundations to solve liquefaction and anti-seepage problems.

[0035] Compared with the scattered point-type mixing pile composite foundation, the grid-type mixing pile composite foundation can use the same construction machinery and construction technology, and can use the same solidifying material to form a mixing pile body with similar physical and mechanical properties to share the load with the foundation soil. The difference is that the mixing piles in the grid-type mixing pile composite foundation are overlapped vertically and horizontally to form a grid-like continuous wall. Even if the same solidifying material, mix ratio, water-cement ratio and mixing technology are used, the grid wall will be stronger due to repeated mixing and grouting or powder spraying at the overlap. The grid wall will also form an enclosure structure to constrain the shear deformation of the foundation, thereby achieving the effect of improving the anti-liquefaction performance. Therefore, the grid-like arrangement is more superior than the scattered point arrangement.

[0036] After comprehensive comparison, in order to meet the requirements of bearing capacity, stability, deformation, liquefaction resistance and reliability, the foundation treatment of this project adopts a composite foundation treatment solution of prefabricated pipe piles combined with grid-shaped or scattered mixing piles according to actual conditions.

[0037] Considering the advantages and disadvantages of the above treatment methods, the final foundation treatment plan is determined as follows: first use grid-shaped or bulk cement mixing piles for treatment, effectively support the slope and prevent the foundation pit from rising; for under-consolidated soft soil, the consolidation settlement of the soil between piles after deep mixing pile treatment is still difficult to solve, and the treatment effect is not very good. The post-construction settlement is still too large. In order to meet the requirements of settlement and base stress, a rigid long pile solution is required. The cast-in-place pile solution is similar to the pipe pile solution, but the cost is 600,000 yuan more than the pipe pile solution. Therefore, the long piles of this solution use prefabricated pipe piles, and cement mixing piles and pipe piles can form a better rigid-flexible composite pile foundation. In order to prevent the pump station bottom plate from being emptied from the foundation, a row of mixing piles is used around the bottom plate for enclosure, and a grouting pipe is preset on the bottom surface of the bottom plate for grouting.

[0038] It is worth noting that foundation clearing operations are required before construction. The base surface that needs to be cleared includes the joint surface between the embankment and the newly built embankment, the embankment foot platform, the foundation base of the covering and other parts. In order to facilitate the connection between the new and old embankments, the embankment joint surface should be excavated into steps, and the foundation clearing boundary should be 30cm to 50cm outside the designed base surface edge. The foundation cleaning includes removing grass, reed roots, tree roots, humus, construction waste, chiseling out concrete pavement and other debris.

[0039] The main construction procedures of this scheme are: construction of interception cofferdam → pumping water and clearing silt from foundation pit → leveling the site → construction of piling platform with 1m thick stone powder filling and 300mm thick brick slag on top → driving mixing piles → construction of prestressed pipe piles → excavation of foundation pit → construction of prestressed pipe pile caps → leveling → laying of geotextile → laying of 50 cm sand cushion → construction of upper buildings.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sluice pump engineering foundation treatment structure, used to optimize the existing sluice pump engineering foundation treatment scheme, characterized by: The invention comprises a bulk mixing pile (2), a fence type mixing pile (3) and a combined mixing pile (4) respectively arranged in a thick soft soil layer (1); a prefabricated pipe pile (5) is arranged between the bulk mixing pile (2), the fence type mixing pile (3) and the combined mixing pile (4); a cast-in-place pile row retaining wall (6) is arranged outside the bulk mixing pile (2), the fence type mixing pile (3) and the combined mixing pile (4); a weathering layer (7) is placed at the bottom of the bulk mixing pile (2), the fence type mixing pile (3) and the combined mixing pile (4); a construction platform (9) is formed on the top by backfilling soil (8); a crushed stone cushion layer is laid on the construction platform (9); and a turf slope protection (10) is provided on the top of the construction platform (9) and above the crushed stone cushion layer.

2. A sluice pump engineering foundation treatment structure according to claim 1, characterized in that: The weathered layer (7) is weathered granite.

3. A sluice pump engineering foundation treatment structure according to claim 1, characterized in that: The prefabricated pipe pile (5) adopts a 500AB100 type prestressed concrete pipe pile, and its mechanical performance index requirements are that the pile body outer diameter is greater than 500mm and the anti-cracking bending moment is greater than 121kN xm.

4. A sluice pump engineering foundation treatment structure according to claim 1, characterized in that: The weathered layer (7) includes a strongly weathered layer and a medium weathered layer, and the pile ends of the cast-in-place piles formed by the bulk mixing piles (2), the fence-type mixing piles (3) and the combined mixing piles (4) are inserted 2m into the strongly weathered layer or the medium weathered layer, and the vertical bearing capacity of a single pile is not less than 1200 kN.

5. The foundation treatment structure for a sluice pump project according to claim 1 is characterized by: The bulk mixing piles (2), the fence-type mixing piles (3) and the combined mixing piles (4) are also reinforced by reinforcement materials, and the reinforcement materials are ordinary cement with a strength grade of not less than 42.5 MPa.

6. The foundation treatment structure for a sluice pump project according to claim 1 is characterized by: A construction joint is formed between each section of concrete in the bulk mixing pile (2), the fence-type mixing pile (3) and the combined mixing pile (4).

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