Counter-force system for pile foundation anti-pulling experiment of soft soil foundation

Abstract

The invention relates to the technical field of constructional engineering, and discloses a soft soil foundation pile foundation anti-pulling test counter-force system which comprises a main counter-force beam which is of a combined box type structure, is horizontally arranged above a test pile and is used for bearing an anti-pulling test load; the two supporting legs are of I-shaped steel stand column structures, are respectively arranged below the two end parts of the main counter-force beam and are used for vertically transmitting the pull-out test load to a foundation from the main counter-force beam; the two foundation supporting base plates are fixedly connected to the bottoms of the two supporting legs correspondingly and used for dispersing the concentrated loads transmitted by the supporting legs into surface loads and applying the surface loads to the surface of the soft soil foundation. Waste steel on a construction site is machined into core components such as the main counter-force beam, the supporting legs and the foundation supporting base plate through cutting and welding processes, efficient secondary utilization of construction waste is achieved, the leasing or purchasing cost of traditional counter-force system equipment is omitted, and time consumption of external coordination and transportation is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building engineering, in particular to a soft soil foundation pile anti-pulling experimental reaction force system. BACKGROUND

[0002] In the field of building engineering, pile anti-pulling test is a key link to evaluate the bearing capacity of pile foundation under the action of upward pulling force, especially in soft soil foundation area, because the bearing capacity of foundation soil is low and the compressibility is high, the anti-pulling stability of pile foundation is directly related to the safety of the upper structure. As the core supporting equipment of anti-pulling test, the rationality, stability and economy of the structure of the reaction force system have important influence on the reliability of the test results and the efficiency of the project promotion.

[0003] The traditional pile anti-pulling test reaction force system mostly uses cast-in-place concrete piers or purchased standard steel structure supports. Although the cast-in-place concrete pier can provide larger bearing capacity, it has the problems of long construction period, large material consumption and difficult to reuse after forming, and is easy to crack due to uneven settlement of the foundation in soft soil foundation, affecting the test precision. Although the purchased standard steel structure support is convenient to install, it needs to rely on external equipment leasing or purchasing, which not only has high leasing cost, but also needs to bear additional time cost such as equipment transportation and coordination of access, and is difficult to adapt to the site conditions and test load requirements of different sites.

[0004] At the same time, the traditional reaction force system has obvious limitations in structural design: some steel structure supports are not optimized for the characteristics of soft soil foundation, the contact area of the support leg with the foundation is small, which is easy to cause excessive local pressure of the foundation and settlement; the main reaction beam mostly uses single steel section, which has insufficient bending stiffness and stability, and is easy to produce excessive deformation in large load test, resulting in distortion of test data; the strength of the connecting part of the component is insufficient, which may cause load transmission interruption or structural instability and other safety hazards.

[0005] In addition, a large amount of waste steel (such as idle steel plate, I-beam and channel steel) is usually generated on the construction site. If these steels are not reasonably utilized, not only the resources are wasted, but also additional cost is needed for disposal, which is contrary to the current development concept of green construction and circular economy. The traditional reaction force system does not consider the secondary utilization of resources on the construction site, which further increases the economic and environmental burden of the project.

[0006] Therefore, the purpose of the present application is to provide a soft soil foundation pile anti-pulling experimental reaction force system to solve the problems in the prior art. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a soft soil foundation pile anti-pulling experimental reaction force system, which solves the problems of large material consumption and difficult to reuse after forming.

[0008] In order to achieve the above object, the present application is implemented by the following technical solutions: A soft soil foundation pile uplift resistance experiment reaction force system, comprising: A main reaction force beam, which is a combined box structure, is horizontally arranged above the test pile and is used for bearing the uplift test load; Two legs, which are I-shaped steel column structures, are arranged below the two ends of the main reaction force beam respectively and are used for vertically transmitting the uplift test load from the main reaction force beam to the foundation; Two foundation support base plates are fixedly connected to the bottoms of the two legs respectively and are used for dispersing the concentrated load transmitted by the legs into a surface load and applying the surface load to the soft soil foundation surface.

[0009] Preferably, the combined box structure of the main reaction force beam comprises: Two channel steels arranged back to back along the length direction thereof; An upper cover plate connected to the upper flanges of the two channel steels; A lower cover plate connected to the lower flanges of the two channel steels; The upper cover plate and the lower cover plate and the two channel steels jointly constitute a closed box section through welding.

[0010] Preferably, the inside of the main reaction force beam is further provided with: At least one internal stiffening rib connected between the webs of the two channel steels; An end plate welded to the two ends of the main reaction force beam; An intermediate transverse stiffening plate transversely arranged at the intermediate position of the length direction of the main reaction force beam.

[0011] Preferably, the I-shaped steel column structure of the leg comprises: An I-shaped steel main body; A top connecting plate fixed to the top of the I-shaped steel main body and used for connecting with the main reaction force beam; A bottom base plate fixed to the bottom of the I-shaped steel main body and used for connecting with the foundation support base plate.

[0012] Preferably, the main reaction force beam, the leg and the foundation support base plate are all made of the construction site waste steel materials through cutting and welding processes.

[0013] Preferably, the foundation support base plate is an independent steel plate component and is fixedly connected to the bottom base plate of the leg through a load-bearing weld.

[0014] Preferably, the cross-sectional size and material properties of the main reaction force beam are determined according to the preset bending strength checking, so as to ensure that the maximum bending normal stress generated when the main reaction force beam bears the uplift test load is not greater than the design value of the bending strength of the material thereof.

[0015] Preferably, the cross-sectional size and material properties of the main reaction beam are also determined according to the preset stiffness check to ensure that the maximum deflection thereof under the design load is within the allowable deflection range.

[0016] Preferably, the cross-sectional size and length of the leg are determined according to the stability check as an axial compression member to ensure that the leg remains stable when subjected to axial compression.

[0017] Preferably, the bottom area of the foundation support pad is determined according to the allowable bearing capacity of the soft soil foundation to ensure that the pressure intensity exerted by the foundation support pad on the surface of the soft soil foundation is not greater than the allowable bearing capacity.

[0018] The present application provides a soft soil foundation pile uplift test reaction system. It has the following advantages: 1. The main reaction beam of the present application adopts a combined box structure, and the leg of the I-shaped steel column structure forms a cooperative force system. The main reaction beam is subjected to bending strength and stiffness check to ensure that the bending stress and deflection are controllable. The leg is prevented from instability by axial compression stability optimization. The foundation support pad is designed according to the allowable bearing capacity of the foundation to disperse the load. This scientific structure design and parameter check mechanism effectively solves the problem of low bearing capacity of soft soil foundation, ensures stable load transmission and controllable structure deformation during the uplift test process, and significantly improves the accuracy of test data and the safety of system operation.

[0019] 2. The present application processes the construction site waste steel into core components such as main reaction beams, legs and foundation support pads through cutting and welding processes, achieving efficient secondary utilization of construction waste. This design not only saves the rental or purchase cost of traditional reaction system equipment, reduces the time consumption of external coordination and transportation, but also reduces resource consumption and carbon emissions caused by new steel production, significantly reduces the cost of uplift test detection, saves time cost for engineering construction, and realizes double improvement of economic benefit and environmental benefit.

[0020] 3. The present application improves the practicability and adaptability of the reaction system through modular structure design. The closed box cross-section of the main reaction beam and the internal stiffening components enhance the structural integrity. The reliable connection of the leg with the main reaction beam and the foundation support pad forms a complete force transmission path, and the size of each component can be flexibly adjusted according to the test requirements. This design makes the system easy to install and operate, and can be quickly put into use without complex on-site debugging, which not only meets the requirements of pile uplift test under different soft soil foundation conditions, but also effectively improves the universality and construction flexibility of the equipment, providing an efficient solution for on-site test. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure shows the main reaction beam of the present application. Figure 2 Fig. 2 is a schematic view of the top and bottom of the main counter-force beam of the present application; Figure 3 Fig. 3 is a schematic view of the main body of the I-beam of the present application; Figure 4 Fig. 4 is a schematic view of the bottom cross-section of the main body of the I-beam of the present application; Figure 5 Fig. 5 is a schematic view of the top cross-section of the main body of the I-beam of the present application; Figure 6 Fig. 6 is a schematic view of the stiffened plate of the present application.

[0022] In the figure, 1 is the main counter-force beam; 11 is the channel steel; 12 is the upper cover plate; 13 is the lower cover plate; 14 is the stiffening rib; 15 is the end sealing plate; 16 is the stiffened plate; 2 is the leg; 21 is the main body of the I-beam; 22 is the connecting plate; 23 is the base plate; 3 is the support pad. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0024] Please refer to the accompanying drawings of the present application Figure 1 - the accompanying drawings of the present application Figure 6 The embodiments of the present application provide a soft soil foundation pile uplift resistance experiment counter-force system, which comprises: The main counter-force beam 1 is a combined box structure, which is horizontally arranged above the test pile and used for bearing the uplift test load; The two legs 2 are I-beam column structures, which are respectively arranged below the two end portions of the main counter-force beam 1 and used for vertically transmitting the uplift test load from the main counter-force beam 1 to the foundation; The two foundation support pads 3 are respectively fixedly connected to the bottom portions of the two legs 2 and used for dispersing the concentrated load transmitted by the legs 2 into surface load and applying the surface load to the soft soil foundation surface.

[0025] The combined box structure of the main counter-force beam 1 comprises: Two channel steels 11 which are arranged back to back along the length direction thereof; An upper cover plate 12 which is connected to the upper flanges of the two channel steels 11; A lower cover plate 13 which is connected to the lower flanges of the two channel steels 11; The upper cover plate 12 and the lower cover plate 13 and the two channel steels 11 jointly constitute a closed box cross-section through welding; Specifically, the combined box structure of the main counter-force beam 1 comprises: two channel steels 11 arranged back-to-back along the length direction, the groove structure of the channel steel 11 can enhance the cross-sectional moment of inertia and improve the overall bending resistance; an upper cover plate 12 connected to the upper flanges of the two channel steels 11; a lower cover plate 13 connected to the lower flanges of the two channel steels 11; the upper cover plate 12 and the lower cover plate 13 and the two channel steels 11 together form a closed box cross-section through welding. The closed cross-section form can reduce stress concentration compared to the open structure, so that the mechanical properties of the material can be fully utilized, and the overall structure and torsional stiffness are also enhanced.

[0026] The main counter-force beam 1 is further provided with: at least one internal stiffening rib 14 connected between the webs of the two channel steels 11; an end sealing plate 15 welded at both ends of the main counter-force beam 1; a middle transverse stiffening plate 16 transversely arranged at the middle position of the length direction of the main counter-force beam 1; Specifically, the main counter-force beam 1 is further provided with: at least one internal stiffening rib 14 connected between the webs of the two channel steels 11, the stiffening ribs 14 are arranged at intervals along the length direction of the beam, which can effectively prevent the webs of the channel steels 11 from local buckling under the action of shear force; an end sealing plate 15 welded at both ends of the main counter-force beam 1, the sealing plate can seal the end of the box cross-section, avoiding the structure from collapsing when the end is under stress, and at the same time enhancing the local pressure bearing capacity of the beam end; a middle transverse stiffening plate 16 transversely arranged at the middle position of the length direction of the main counter-force beam 1, the middle stiffening plate 16 can strengthen the structural stiffness of the mid-span region, resist the maximum bending moment generated by the test load, and reduce the mid-span deflection.

[0027] The I-beam column structure of the leg 2 comprises: an I-beam body 21; a top connecting plate 22 fixed to the top of the I-beam body 21 for connecting with the main counter-force beam 1; a bottom base plate 23 fixed to the bottom of the I-beam body 21 for connecting with the foundation support pad 3; Specifically, the I-beam column structure of the leg 2 comprises: an I-beam body 21, the cross-sectional characteristics of the I-beam make it have high stability when bearing axial pressure, which is suitable as a vertical force transmission member; a top connecting plate 22 fixed to the top of the I-beam body 21 for connecting with the main counter-force beam 1, the connecting plate 22 is connected with the main counter-force beam 1 through U-shaped bolts, which is convenient for disassembly and utilization; a bottom base plate 23 fixed to the bottom of the I-beam body 21 for connecting with the foundation support pad 3, the base plate 23 increases the contact area between the leg 2 and the pad, avoiding local crushing of the pad by the end of the leg 2.

[0028] The main counter-force beam 1, the leg 2 and the foundation support pad 3 are all made of waste steel materials on the construction site through cutting and welding processes. Specifically, the main counterforce beam 1, the leg 2 and the foundation support pad 3 are all made of waste steel materials on the construction site through cutting and welding process. After the waste steel plates, I-beams and other steel materials on the construction site are detected to meet the mechanical property requirements, their sizes are adjusted through precise cutting, and then they are welded to form the required components. This way not only realizes the resource utilization of construction waste, reduces the manufacturing cost of equipment, but also reduces the time cost and environmental burden caused by the procurement and transportation of new materials.

[0029] The foundation support pad 3 is an independent steel plate component, which is fixedly connected with the bottom base plate 23 of the leg 2 through a load-bearing weld; Specifically, the foundation support pad 3 is an independent steel plate component, which is fixedly connected with the bottom base plate 23 of the leg 2 through a load-bearing weld. The load-bearing weld adopts a double-bevel welding process to ensure that the weld strength is not less than the strength of the base material, so that the vertical pressure of the leg 2 can be effectively transmitted. The independent steel plate design allows the pad to be flexibly adjusted in size according to the foundation conditions, adapt to the bearing requirements of different soft foundations, and facilitate individual replacement and maintenance.

[0030] The cross-sectional size and material properties of the main counterforce beam 1 are determined according to the preset bending strength check, to ensure that the maximum bending normal stress generated when the main counterforce beam 1 bears the uplift test load is not greater than the design value of the bending strength of the material; Specifically, the cross-sectional size and material properties of the main counterforce beam 1 are determined according to the preset bending strength check, to ensure that the maximum bending normal stress generated when the main counterforce beam 1 bears the uplift test load is not greater than the design value of the bending strength of the material. In the design process, the bending moment distribution of the beam under the test load is obtained through structural mechanics calculation, and the parameters such as the type of channel steel 11 and the thickness of the cover plate are determined in combination with the yield strength and safety factor of the material, to avoid the fracture damage of the beam due to excessive bending stress.

[0031] The cross-sectional size and material properties of the main counterforce beam 1 are also determined according to the preset stiffness check, to ensure that the maximum deflection of the main counterforce beam 1 under the design load is within the allowable deflection range; Specifically, the cross-sectional size and material properties of the main counterforce beam 1 are also determined according to the preset stiffness check, to ensure that the maximum deflection of the main counterforce beam 1 under the design load is within the allowable deflection range, so that the deflection value does not exceed the allowable limit value specified in the specification, to avoid the excessive deformation affecting the accuracy of the test data.

[0032] The cross-sectional size and length of the leg 2 are determined according to the stability check of the axial compression component, to ensure that the leg 2 remains stable when bearing the axial pressure; Specifically, the cross-sectional size and length of the leg 2 are determined according to the stability check of the axial compression component, to ensure that the leg 2 remains stable when bearing the axial pressure, to avoid the bending instability or overall overturning of the leg 2 under the action of the axial pressure, and to ensure the safety of the vertical force transmission path.

[0033] The bottom area of the foundation support pad 3 is determined according to the allowable bearing capacity of the soft soil foundation, so as to ensure that the pressure intensity of the foundation support pad 3 applied to the surface of the soft soil foundation is not greater than the allowable bearing capacity; Specifically, the bottom area of the foundation support pad 3 is determined according to the allowable bearing capacity of the soft soil foundation, so as to ensure that the pressure intensity of the foundation support pad 3 applied to the surface of the soft soil foundation is not greater than the allowable bearing capacity. The characteristic value of the allowable bearing capacity of the soft soil foundation is obtained through geological exploration, and the minimum pad area required = total load ÷ foundation allowable bearing capacity is calculated in combination with the vertical load transmitted by the support leg 2, and a safety factor is appropriately enlarged to prevent plastic deformation or settlement caused by local compressive stress exceeding the limit.

[0034] Working principle: The main counterforce beam 1 is horizontally placed above the test pile as a core load-bearing component, which is formed by welding two back-to-back channel steels 11, an upper cover plate 12 and a lower cover plate 13 into a closed box section, greatly improving the bending stiffness and carrying capacity. The stiffening rib 14 arranged inside enhances the stability of the web of the channel steel 11, the end sealing plate 15 strengthens the integrity of the beam end, and the intermediate transverse stiffening plate 16 improves the mid-span shear capacity. The cross-sectional size and material properties are determined through bending strength and stiffness checking to ensure that the maximum bending normal stress does not exceed the material design value and the deflection is controlled within the allowable range, thereby ensuring the accuracy of the test.

[0035] The two support legs 2 are I-beam column structures arranged below the two ends of the main counterforce beam 1 respectively to bear the vertical load transmission function. The top of the I-beam main body 21 is firmly connected with the main counterforce beam 1 through the connecting plate 22, and the bottom is connected with the foundation support pad 3 through the base plate 23 to form a complete force transmission path. The cross-sectional size and length of the support leg 2 are designed according to the stability requirements of the axial compression member to prevent bending or torsional instability by optimizing the slenderness ratio and moment of inertia parameters, thereby ensuring the safe transmission of axial pressure.

[0036] The foundation support pad 3 is used as the contact component of the system and the foundation, and is connected to the bottom of the support leg 2 by a load-bearing weld. The bearing capacity of the soft soil foundation is low, and the pad disperses the concentrated load transmitted by the support leg 2 into a surface load by increasing the stressed area. The bottom area of the pad is determined according to the allowable bearing capacity of the soft soil foundation to ensure that the pressure intensity applied to the surface of the foundation does not exceed the limit, thereby avoiding foundation settlement or damage and providing stable support for the system.

[0037] The system components are all made of construction site waste steel materials through cutting and welding processing, which not only realizes resource recycling and reduces cost, but also flexibly adapts to test requirements. During the test, the pulling force of the loading device is transmitted to the main counterforce beam 1 through the test pile, and then distributed to the supporting legs 2 by the main counterforce beam 1. The supporting legs 2 transmit the load to the foundation supporting pads 3, and finally the load is dispersed and transmitted to the soft soil foundation through the pads. In the whole process, the components work together through the preset strength, stiffness and stability checking mechanism to form a stable and reliable force transmission system, which provides accurate data support for the soft soil pile foundation uplift test, and has technical practicability and environmental protection and economy.

[0038] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A piling test reaction system for soft soil foundations, characterized in that, include: The main reaction beam (1) is a composite box structure, which is horizontally set above the test pile to bear the pull-out test load; Two support legs (2), which are I-beam column structures, are respectively set below the two ends of the main reaction beam (1) to vertically transfer the pull-out test load from the main reaction beam (1) to the foundation; Two foundation support pads (3) are fixedly connected to the bottom of the two legs (2) respectively, and are used to distribute the concentrated load transmitted by the legs (2) into surface load and apply it to the surface of the soft soil foundation.

2. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The combined box-type structure of the main reaction beam (1) includes: Two channel steels (11) are arranged back to back along their length. The upper cover plate (12) is connected to the upper flange of the two channel steels (11); The lower cover plate (13) is connected to the lower flange of the two channel steels (11); The upper cover plate (12) and the lower cover plate (13) together with the two channel steels (11) form a closed box-shaped cross section by welding.

3. The soft soil foundation pile foundation pull-out test reaction system according to claim 2, characterized in that, The main reaction beam (1) is also equipped with: At least one internal stiffening rib (14) is connected between the webs of two channel steels (11); End caps (15) welded to both ends of the main reaction beam (1); A transverse stiffening plate (16) is set transversely at the middle position of the main reaction beam (1) along its length.

4. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The I-beam column structure of the support leg (2) includes: I-beam body (21); A top connecting plate (22) fixed to the top of the I-beam body (21) is used to connect with the main reaction beam (1); The bottom base plate (23) is fixed to the bottom of the I-beam body (21) and is used to connect with the foundation support plate (3).

5. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The main reaction beam (1), the legs (2) and the foundation support plate (3) are all made from scrap steel from the construction site through cutting and welding processes.

6. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The foundation support plate (3) is an independent steel plate component, which is fixedly connected to the bottom base plate (23) of the support leg (2) through a load-bearing weld.

7. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The cross-sectional dimensions and material properties of the main reaction beam (1) are determined according to the preset bending strength check, in order to ensure that the maximum bending normal stress generated when it is subjected to the pull-out test load is not greater than the design value of the bending strength of its material.

8. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The cross-sectional dimensions and material properties of the main reaction beam (1) are also determined according to the preset stiffness check to ensure that its maximum deflection under the design load is within the allowable deflection range.

9. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The cross-sectional dimensions and length of the outrigger (2) are determined based on the stability check of the axially compressed component to ensure that it remains stable when subjected to axial pressure.

10. The experimental reaction system for pull-out resistance of pile foundations in soft soil according to claim 1, characterized in that, The bottom area of ​​the foundation support pad (3) is determined by checking the allowable bearing capacity of the soft soil foundation, so as to ensure that the pressure applied by the foundation support pad (3) to the surface of the soft soil foundation is not greater than the allowable bearing capacity.

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