Steel pipe pile supporting structure suitable for metro foundation pit in sandy gravel stratum

Abstract

The utility model relates to the technical field of steel pipe pile supporting structures, in particular to a steel pipe pile supporting structure suitable for a sandy gravel stratum subway foundation pit, which comprises a foundation pit and a plurality of guide holes mechanically formed in the sandy gravel stratum of the foundation pit, steel pipes are driven into the guide holes, top beams are fixedly arranged at the tops of the steel pipes, one ends of the steel pipes are anchored into the top beams, and the other ends of the steel pipes are anchored into the foundation pit. Steel supports are fixedly arranged at the tops of the steel pipes, the steel supports are located between the top beams, and a proposed subway channel structure is formed in the bottoms of the steel supports. By arranging the steel pipe concrete combined piles, the rigidity and bearing capacity of the steel pipes are remarkably improved, lateral soil pressure and water pressure can be better resisted, and foundation pit deformation is effectively controlled; the cast-in-place reinforced concrete top beam is arranged at the tops of the steel pipes, the row of steel pipe piles are connected into a whole, the integrity and stability of the supporting structure are enhanced, the supporting structure can better adapt to stratum changes, and the risk of supporting failure caused by uneven stratums is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to steel pipe pile support structure technical field, especially suitable for sand pebble stratum subway foundation pit's steel pipe pile support structure. BACKGROUND

[0002] At present, in the construction of urban rail transit in China, a large number of subway station personnel exit and entrance passages are shallow in depth, and the personnel exit and entrance passages are mostly constructed by using open excavation method. In a large number of subway station entrances and exits in urban areas, due to the lack of space for slope excavation, foundation pit support structures need to be set. In the subway construction of sand pebble stratum in the southwest region of China, the personnel exit and entrance passage foundation pit mostly uses reinforced concrete piles as foundation pit support structures. However, for the exit and entrance passage foundation pit with shallow depth, using ordinary reinforced concrete support piles with large diameter as temporary enclosure structures has extremely high cost and poor economy.

[0003] In the case of subway foundation pit excavation in sand pebble stratum, the steel pipe pile is difficult to be driven in, and the insufficient rigidity of the support structure leads to the instability of the foundation pit. In view of this, the utility model provides a steel pipe pile support structure suitable for sand pebble stratum subway foundation pit. UTILITY MODEL CONTENTS

[0004] The main purpose of the utility model is to provide a steel pipe pile support structure suitable for sand pebble stratum subway foundation pit, so as to solve the problem of instability of the foundation pit caused by the difficulty of driving the steel pipe pile into the sand pebble stratum and the insufficient rigidity of the support structure in the case of subway foundation pit excavation in sand pebble stratum.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the utility model, a steel pipe pile support structure suitable for sand pebble stratum subway foundation pit is provided, which comprises a foundation pit and a plurality of guide holes opened in the sand pebble stratum of the foundation pit by a machine, a steel pipe is driven into the guide hole, a corbel is fixedly arranged at the top of the steel pipe, and one end of the steel pipe is anchored into the corbel, a steel support is fixedly arranged at the top of the steel pipe, and the steel support is located between the corbels, and a subway passage structure to be constructed is arranged at the bottom of the steel support.

[0006] Further, fine stone concrete is poured into the steel pipe, and cement mortar is grouted in the gap between the outer wall of the steel pipe and the inner wall of the guide hole.

[0007] Further, the one end of the steel pipe is anchored into the corbel by not less than 1.5d, and the corbel and the steel pipe are fixedly connected as a whole by pouring.

[0008] Further, the distance from the bottom of the steel support to the foundation pit is 0.5m.

[0009] Further, a pile-to-pile net spray horizontal reinforcing rib is welded between the outer walls of two adjacent steel pipes, and an outer surface of the pile-to-pile net spray horizontal reinforcing rib is sprayed with a pile-to-pile net spray layer.

[0010] Further, the steel pipe has a diameter less than 400 mm.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] 1. In the steel pipe pile supporting structure suitable for sand pebble stratum subway foundation pit, the steel pipe concrete composite pile is arranged, the rigidity and the bearing capacity of the steel pipe are obviously improved, the lateral soil pressure and the water pressure can be better resisted, and the foundation pit deformation can be effectively controlled.

[0013] 2. In the steel pipe pile supporting structure suitable for sand pebble stratum subway foundation pit, the cast-in-situ reinforced concrete crown beam is arranged at the top of the steel pipe, a row of steel pipe piles are connected into a whole, the integrity and the stability of the supporting structure are enhanced, the supporting structure can better adapt to stratum change, and the supporting failure risk caused by stratum inhomogeneity is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is a steel pipe pile supporting structure transverse section view in the preferred embodiment of the utility model;

[0015] Figure 2 It is a steel pipe pile transverse section structure view in the preferred embodiment of the utility model;

[0016] Figure 3 It is a plane view of the connection between the steel pipe pile and the crown beam in the preferred embodiment of the utility model;

[0017] Figure 4 It is an elevation view of the connection between the steel pipe pile and the crown beam in the preferred embodiment of the utility model;

[0018] Figure 5 It is a pile-to-pile net spray structure view of the steel pipe pile in the preferred embodiment of the utility model.

[0019] ILLUSTRATIVE DESCRIPTION

[0020] 1, lead hole; 2, steel pipe; 3, fine stone concrete; 4, cement mortar; 5, crown beam; 6, steel support; 8, pile-to-pile net spray horizontal reinforcing rib; 7, pile-to-pile net spray layer; 9, proposed subway passage structure. DETAILED DESCRIPTION

[0021] In order to further illustrate the technical means and effects adopted by the utility model to achieve the predetermined utility model purposes, the specific embodiments, structures, features and effects according to the utility model are described in detail as follows in combination with the drawings and the preferred embodiments.

[0022] Please refer to Figures 1-5 The embodiment aims to provide a steel pipe pile supporting structure suitable for a subway foundation pit in a sandy pebble stratum, which comprises a foundation pit and a plurality of guide holes 1 formed in the sandy pebble stratum of the foundation pit by a machine, a steel pipe 2 is driven into the guide hole 1, a corbel 5 is fixedly arranged at the top of the steel pipe 2, and the steel pipe 2 is anchored into the corbel 5 at one end, a steel support 6 is fixedly arranged at the top of the steel pipe 2, and the steel support 6 is located between the corbels 5, and a subway passage structure 9 to be constructed is arranged at the bottom of the steel support 6.

[0023] The machine for forming the guide hole 1 is preferably a down-the-hole drill. The down-the-hole drill is particularly suitable for deep hole drilling in the sandy pebble stratum due to its strong drilling capacity and adaptability. The guide hole 1 has a diameter greater than that of the steel pipe 2, generally with a gap of 5-10 mm, so that the steel pipe 2 can be smoothly and tightly driven into the guide hole 1. The depth of the guide hole 1 is determined according to the geological survey results and the design depth of the foundation pit, so as to ensure that the steel pipe 2 can penetrate the unstable stratum and meet the expected bearing capacity requirement. Before the guide hole 1 is formed, detailed geological survey must be conducted to understand the stratum distribution, soil mechanical properties and other information, so as to provide a basis for the depth of the guide hole 1 and the selection of the steel pipe 2.

[0024] After the guide hole 1 is formed, the steel pipe 2 should be immediately driven into the guide hole 1. During the driving process, the driving speed and force should be strictly controlled to avoid excessive disturbance to the surrounding stratum. At the same time, the driving condition of the steel pipe 2 should be observed at any time to ensure that the steel pipe 2 can smoothly penetrate the unstable stratum and reach the design depth.

[0025] After the steel pipe 2 is driven, fine stone concrete 3 is poured into the steel pipe 2. The fine stone concrete 3 has good fluidity and filling property, and can fully fill the inside of the steel pipe 2 to form a tight concrete structure. During the pouring process, a vibrating rod should be used for vibration to remove air bubbles in the fine stone concrete 3, improve the compactness and uniformity of the fine stone concrete 3, and timely close the pouring opening after pouring to the design height to prevent the fine stone concrete 3 from flowing out. After the pouring is completed, the fine stone concrete 3 inside the steel pipe 2 should be fully maintained to ensure that the fine stone concrete 3 reaches the design strength. During the maintenance period, the surface of the fine stone concrete 3 should be kept wet to avoid dry cracking and strength reduction.

[0026] The gap between the outer wall of the steel pipe 2 and the inner wall of the hole 1 is filled with cement mortar 4, which has good adhesion and fluidity and can fully fill the gap between the outer wall of the steel pipe 2 and the inner wall of the hole 1. During grouting, the grouting pressure and grouting speed should be controlled to avoid excessive pressure on the steel pipe 2 and the surrounding stratum. After the gap is completely filled, the grouting port should be closed in time to prevent the cement mortar 4 from flowing out. After grouting is completed, the cement mortar 4 should be fully maintained to ensure that it reaches the designed strength. At the same time, the grouting port and the surrounding of the steel pipe 2 should be regularly inspected to ensure that there are no quality problems such as leakage and cracks.

[0027] The reinforcement of the corbel beam 5 is tied, and the steel pipe 2 is anchored into the corbel beam 5 at one end with a length of not less than 1.5d (d is the diameter of the steel pipe 2). The corbel beam 5 is integrally connected with the steel pipe 2 by pouring to form a whole. The corbel beam 5 not only plays a role in connecting and fixing the steel pipe 2, making a row of steel pipes 2 into a whole to form a stable support structure, but also provides a solid support point for the subsequent steel support 6. The steel support 6 is connected to the corbel beam 5, which can further increase the bearing capacity and stability of the support structure to ensure safety during excavation of the foundation pit.

[0028] After the concrete strength of the corbel beam 5 reaches the designed strength, the foundation pit is excavated to the bottom of the foundation pit according to the underground water level of the site, and the steel support 6 is erected. The steel support 6 is located between the corbel beams 5. During erection, the connection between the steel support 6 and the corbel beam 5 should be firm and reliable, and the steel support 6 itself should be in a stable state. The bottom of the steel support 6 is 0.5m from the foundation pit, and enough space should be reserved at the bottom to open the proposed subway passage structure 9 for subsequent construction operations.

[0029] A pile-to-pile net spraying horizontal reinforcing rib 8 is welded between the outer walls of two adjacent steel pipes 2. These reinforcing ribs not only enhance the connection between the steel pipes 2, forming a more compact and stable support system, but also significantly improve the lateral force resistance and deformation resistance of the overall support structure. The pile-to-pile net spraying horizontal reinforcing rib 8 is sprayed with a pile-to-pile net coating 7 on the outer surface. This step mainly uses the technology of sprayed concrete to form a dense protective net on the surface of the pile-to-pile net spraying horizontal reinforcing rib 8. This protective net not only has excellent adhesion and impermeability, which can effectively prevent the soil on the side wall of the foundation pit from falling off and collapsing due to uneven stress or water erosion, but also further enhances the integrity and durability of the support structure.

[0030] Subsequently, the proposed subway passage structure 9 is poured. During pouring, the quality of the concrete needs to be strictly controlled, including the mix proportion, slump, pouring speed and other key parameters, to ensure that the strength and durability of the poured structure meet the design requirements. At the same time, attention should be paid to the vibration and maintenance of the concrete to improve the compactness and crack resistance of the concrete.

[0031] The subway tunnel structure 9 to be built refers to an underground tunnel structure planned and designed for constructing a subway system. The main structure of the subway tunnel is usually lined with reinforced concrete or precast concrete components, which have high strength, durability, and impermeability, and can effectively withstand the pressure of subway trains and underground water.

[0032] The steel pipe 2 has a diameter less than 400 mm. In the subway foundation pit support structure, the steel pipe 2 mainly plays a supporting and protecting role and does not need to bear excessive load. Therefore, by reducing the diameter of the steel pipe 2, the disturbance and damage to the surrounding strata can be minimized while ensuring the supporting effect, which is beneficial to the safety of underground pipelines and surrounding buildings.

[0033] In specific use, first, the construction site of the subway foundation pit is leveled and treated, and precise hole drilling 1 is performed using a down-the-hole drill. After the hole drilling 1 is completed, the steel pipe 2 is punched into the hole 1 one by one, and fine stone concrete 3 is poured into the steel pipe 2. Cement mortar 4 is poured into the gap between the outer wall of the steel pipe 2 and the hole wall of the hole 1, and the steel reinforcement cage of the corbel 5 is bound. In this process, it is necessary to ensure that the top of the steel pipe 2 is firmly anchored into the corbel 5, and the anchoring depth is not less than 1.5d of the diameter of the steel pipe 2. Subsequently, concrete pouring operation of the corbel 5 is performed, so that a row of steel pipes 2 are connected into a whole through the corbel 5. The foundation pit is excavated, and when excavating to a distance of 0.5 meters below the bottom of the steel support 6, the excavation is stopped and the steel support 6 is erected. The inter-pile net spray horizontal reinforcing rib 8 is welded on the outer wall of the adjacent steel pipe 2, and the inter-pile net spray layer 7 is sprayed on the surface of the reinforcing rib. Finally, under the premise of ensuring that the support structure is stable and meets the design requirements, concrete pouring operation of the subway tunnel structure 9 to be built is performed.

[0034] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Although the utility model has been disclosed as above with a preferred embodiment, it is not intended to limit the utility model. Any person skilled in the art can make some changes or modifications to the above-mentioned technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the utility model. Any modification, equivalent change, and modification of the above-mentioned embodiments, which does not depart from the technical solution of the utility model, is still within the scope of the technical solution of the utility model.

Claims

1. A steel pipe pile supporting structure suitable for a subway foundation pit in a sandy pebble stratum, comprising a foundation pit and a plurality of guide holes (1) formed in the sandy pebble stratum of the foundation pit by a machine, characterized in that, The steel pipe (2) is driven into the lead hole (1), the top of the steel pipe (2) is fixedly provided with a crown beam (5), one end of the steel pipe (2) is anchored into the crown beam (5), the top of the steel pipe (2) is fixedly provided with a steel support (6), and the steel support (6) is located between the crown beams (5), and the bottom of the steel support (6) is provided with a planned subway passage structure (9).

2. The steel pipe pile supporting structure suitable for the subway foundation pit in sandy pebble stratum according to claim 1, characterized in that, The steel pipe (2) is internally poured with fine stone concrete (3), and cement mortar (4) is injected into the gap between the outer wall of the steel pipe (2) and the inner wall of the lead hole (1).

3. The steel pipe pile supporting structure suitable for the subway foundation pit in sandy pebble stratum according to claim 1, characterized in that, One end of the steel pipe (2) is anchored into the crown beam (5) by not less than 1.5d, and the crown beam (5) and the steel pipe (2) are fixedly connected as a whole by pouring.

4. The steel pipe pile supporting structure suitable for the subway foundation pit in sandy pebble stratum according to claim 1, characterized in that, The bottom of the steel support (6) is 0.5m to the foundation pit.

5. The steel pipe pile supporting structure suitable for the subway foundation pit in sandy pebble stratum according to claim 1, characterized in that, Adjacent two steel pipes (2) are welded with pile net spraying horizontal reinforcing bars (8) between the outer walls of the steel pipes (2), and the outer surface of the pile net spraying horizontal reinforcing bars (8) is sprayed with a pile net spraying layer (7).

6. The steel pipe pile supporting structure suitable for the subway foundation pit in sandy pebble stratum according to claim 1, characterized in that, The diameter of the steel pipe (2) is less than 400mm.

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