A temporary column pile foundation structure for a subway semi-covered excavation station and its construction method

Abstract

The present invention relates to the technical field of temporary column pile foundation, and discloses a temporary column pile foundation structure and a construction method of a semi-covered subway station, wherein the structure comprises a pile foundation, an enlarged head, and a connector; the enlarged head is connected to the end of the pile foundation away from the surface through a connector; the pile foundation comprises at least one branch plate cavity, and the branch plate cavity is used to place a branch plate; the branch plate comprises a branch plate skeleton, and the branch plate skeleton is used to improve the tensile strength of the branch plate cavity. The temporary column pile foundation structure and construction method obtained by the present invention can be applied in a plastic clay layer, and can improve the friction resistance between the pile foundation and the clay layer.

Description

Technical Field

[0001] The invention relates to the technical field of temporary column pile foundation, and in particular to a temporary column pile foundation structure for a subway semi-covered excavation station and a construction method thereof. Background Art

[0002] Underground subway stations use the traditional open-cut method. Although the cost is low and the civil construction efficiency is high, the initial and time costs are often high due to the relocation of underground municipal pipelines and the relief of ground traffic. The full-cover excavation method can alleviate the problem of ground traffic, but the efficiency of civil construction will be reduced. The dark excavation method can avoid the impact of construction on underground municipal pipelines and ground traffic. However, due to the complex process, it often restricts the overall construction period of the entire line. Therefore, some people proposed to use a temporary semi-cover excavation method. This method has a controllable cost and a moderate construction period. It can alleviate the impact of construction on ground traffic, but it still cannot solve the problem of small sites and insufficient space for the relocation of underground municipal pipelines. In recent years, designers have successively adopted the method of using half of the permanent structure top plate as a temporary cover plate. While maintaining the function of the semi-cover excavation method, it fully utilizes the space above the cover plate as the relocation route for some underground municipal pipelines, backfills the soil above the cover plate, and constructs a permanent pavement.

[0003] However, new problems have arisen. The deadweight of the cover plate and the backfill soil have placed a greater load on the pile foundation under the cover plate. For sites with a deep plastic clay layer below the surface, the increase in load is more likely to cause the pile foundation to sink, resulting in poor structural stability and the risk of collapse. The friction resistance on the side of the pile is only 1 / 10 of the friction resistance on the pile end. Since the friction resistance on the side of the pile is small, technicians often increase the pile length to increase the friction resistance between the pile foundation and the soil layer, thereby preventing the pile foundation from sinking. However, increasing the pile length will cause a sharp increase in the project cost. Some technicians also use the post-grouting cast-in-place pile process, but they find that the post-grouting cast-in-place pile process is not only difficult to ensure the grouting effect, but also has the risk of expanding the bottom and collapsing the hole.

[0004] In view of this, in view of the shortcomings and adaptability limitations of the prior art, a temporary column pile foundation structure for a semi-covered subway station and a construction method thereof are provided. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a temporary column pile foundation structure and a construction method for a semi-covered subway station. The temporary column pile foundation structure and construction method obtained by the present invention can be applied in plastic clay layers, and can improve the friction resistance between the pile foundation and the clay layer.

[0006] The present invention provides a temporary column pile foundation structure for a semi-covered subway station, the structure comprising a pile foundation, an enlarged head, and a connector;

[0007] The end of the pile foundation away from the ground surface is connected to the enlarged head through a connector;

[0008] The pile foundation comprises at least one branch plate cavity, and the branch plate cavity is used for placing a branch plate;

[0009] The branch plate includes a branch plate frame, and the branch plate frame is used to improve the tensile strength of the branch plate cavity.

[0010] Furthermore, the branch plate skeleton is used to improve the tensile strength of the branch plate cavity as follows:

[0011] The branch plate skeleton is umbrella-shaped;

[0012] The support plate comprises a hollow small-diameter steel pipe and a fixing structure; the fixing structure is located inside the small-diameter steel pipe;

[0013] The fixing structure includes a middle rod;

[0014] The middle rod serves as the umbrella axis of the branch plate skeleton. One end of the branch plate skeleton is hingedly connected to the small diameter steel pipe, and the other end of the branch plate skeleton is hingedly connected to the middle rod. When the middle rod moves upward, the branch plate skeleton unfolds to form an umbrella shape. The umbrella-shaped branch plate skeleton is fixed in the branch plate cavity to become the skeleton structure in the branch plate cavity.

[0015] Furthermore, the branch plate frame is fixed in the branch plate cavity specifically as follows:

[0016] The fixing structure also includes a locking steel bar, and the middle rod vertically passes through the interior of the locking steel bar and is fixedly connected to the locking steel bar;

[0017] The locking steel bar is provided with a spring;

[0018] The upward movement of the middle rod drives the fixed structure out of the small diameter steel pipe. At the end of the small diameter steel pipe, the spring recovers and deforms the locking steel bar to be deformed and locked, so that the locking steel bar can no longer enter the small diameter steel pipe.

[0019] Furthermore, as an example, the locking steel bar can be designed as a triangle, the triangular base of the locking steel bar is provided with a spring, the middle rod passes through the locking steel bar, and the middle rod is fixedly connected to the corners of the triangle of the locking steel bar. When the middle rod moves upward, it drives the fixed structure to leave the small diameter steel pipe. At the port of the small diameter steel pipe, the spring recovers the deformation so that the length of the bottom side of the locking steel bar is longer than the diameter of the port of the small diameter steel pipe, so that the locking steel bar can no longer enter the small diameter steel pipe.

[0020] Furthermore, the shape of the locking steel bar can be further improved. In order to enhance the stability of the fixed connection between the middle rod and the locking steel bar so that the locking steel bar can be stably connected to the middle rod during movement, a hollow small pipe that can be fixedly connected to the middle rod can be provided at the corner of the triangle, and a hollow small pipe can also be provided at the base of the triangle. The hollow small pipe connected to the base is used to fix the spring so that when the locking steel bar is in the small diameter steel pipe, the spring can be stably fixed to the base of the triangle.

[0021] Furthermore, the pile foundation also includes a steel cage; the steel cage is provided with grooved steel bars, and the grooved steel bars are fixedly connected to the small-diameter steel pipe to fix the position of the small-diameter steel pipe in the support plate cavity.

[0022] Furthermore, the height of the connector is 1m-2m.

[0023] Furthermore, the pile foundation is inserted into the connector and fixedly connected to the connector, and the height of the pile foundation inserted into the connector is 0.5m-1m.

[0024] Furthermore, the radius of the enlarged head is 1 to 3 times the radius of the pile foundation, and the height of the enlarged head is 2.5m to 4.5m.

[0025] Furthermore, the shortest distance between the branch cavity and the ground surface is the sum of the foundation pit depth H1 and the branch cavity height H2; the shortest distance between adjacent branch cavities is 8 times the branch cavity width W; the shortest distance between the branch cavity and the end of the pile foundation away from the ground surface is not less than the height of one branch cavity.

[0026] Furthermore, the branch disc cavity is rhombus-shaped.

[0027] The present invention also provides a construction method for the temporary column pile foundation structure of the subway semi-covered and excavated station, the method comprising:

[0028] Step S1: hammering the pile pipe into the plastic clay layer at the designed position, and whenever the pile pipe is hammered into 1m-2m, using a heavy hammer in the pile pipe to hammer the soil in the pile pipe out of the pile pipe, and the above steps are repeated;

[0029] Step S2: When the distance between the lower end of the pile pipe and the designed pile bottom differs by 3.5m-5.5m, the weight in the pile pipe is taken out, and waste building materials and quicklime are filled into the pile pipe, and the waste building materials and quicklime in the pile pipe are hammered out of the bottom of the pile pipe by the weight to form an enlarged head;

[0030] Step S3: adding dry hard concrete on the enlarged head through the pile pipe, and tamping with a heavy hammer so that the dry hard concrete can be filled in the enlarged head and a connecting body can be formed on the enlarged head;

[0031] Step S4: inserting the extrusion and expansion branch plate device into the pile pipe, taking out the pile pipe, and preliminarily forming the pile foundation; according to the design position of the branch plate cavity, at the design position, using the extrusion and expansion branch plate device to extrude the plastic clay layer around the extrusion and expansion branch plate device to form a plurality of diamond-shaped branch plate cavities;

[0032] Step S5: After the preparation of the branch plate cavity is completed, the extruded branch plate equipment is taken out, a steel cage is placed in the initially formed pile foundation, and the branch plate is fixed at the branch plate cavity, and finally concrete is poured to finally form a temporary column pile foundation structure.

[0033] Furthermore, in step S2, the steps of filling the pile pipe with waste building materials and quicklime, and hammering the waste building materials and quicklime in the pile pipe out of the bottom of the pile pipe with a heavy hammer to form an enlarged head include:

[0034] The filled abandoned building materials and quicklime are rammed in layers, with each ramming forming a ramming thickness of 0.7m-0.9m, until the height of the enlarged head reaches 2.5m-4.5m.

[0035] Furthermore, the height of the connector is 1m-2m.

[0036] Furthermore, in step S5, the specific steps of fixing the branch plate at the branch plate cavity include:

[0037] Channel-shaped steel bars are fixed on the steel cage at the support plate cavity;

[0038] The grooved steel bar is used to fix the position of the support plate in the support plate cavity. The hollow small-diameter steel pipe in the support plate is fixedly connected to the grooved steel bar.

[0039] The fixing structure includes a locking steel bar and a middle rod, wherein the middle rod vertically passes through the interior of the locking steel bar and is fixedly connected to the locking steel bar;

[0040] The locking steel bar is provided with a spring;

[0041] By pulling the middle rod upward, the fixed structure is driven to leave the small diameter steel pipe. At the end of the small diameter steel pipe, the spring recovers and deforms the locking steel bar, causing it to be deformed and locked, so that the locking steel bar can no longer enter the small diameter steel pipe.

[0042] The branch plate skeleton is umbrella-shaped, and the middle rod serves as the umbrella axis of the branch plate skeleton. One end of the branch plate skeleton is hingedly connected to a small-diameter steel pipe, and the other end of the branch plate skeleton is hingedly connected to the middle rod. When the middle rod moves upward, the branch plate skeleton unfolds to form an umbrella shape. The umbrella-shaped branch plate skeleton is fixed in the branch plate cavity to become the skeleton structure in the branch plate cavity.

[0043] Furthermore, the shortest distance between adjacent branch disc cavities is 8 times the width of the branch disc cavity.

[0044] The embodiments of the present invention have the following technical effects:

[0045] 1. First of all, the environment in which the present invention is based is in a plastic clay layer. Compared with other environments, such as karst areas, it does not need to consider too much about how to increase the frictional resistance between the pile foundation and the plastic clay layer to prevent the pile foundation from sinking. In the present invention, not only is the structure of the enlarged head designed to increase the bearing capacity of the end of the pile foundation, which is conducive to increasing the end resistance at the bottom of the pile foundation, but also a support plate is designed. The support plate is located in the support plate cavity, and the support plate skeleton can increase the tensile shear strength of the support plate, thereby increasing the end resistance of the pile foundation within the range of the pile body; through the above design, the overall vertical bearing capacity of the pile foundation is successfully increased.

[0046] 2. In the present invention, the column hammer tamping and support plate squeezing and expanding effects both increase the density of the soil around and at the bottom of the pile foundation, thereby achieving the purpose of increasing the pile side friction resistance and pile end resistance, and improving the overall vertical bearing capacity of the pile foundation.

[0047] 3. In the method of the present invention, first, the soil around the pile and at the pile end is compacted, and the vertical bearing capacity of the foundation is fully utilized, which can effectively reduce the pile diameter and pile length, while greatly improving the bearing capacity of the pile and reducing the settlement of the pile body. Second, it is adaptable to plastic clay soil layers, has a simple structure and low cost. Third, it fully utilizes construction waste, turning waste into treasure and reducing environmental pollution. Fourth, the support plate is rigidly connected to the steel cage to improve the shear resistance between the support plate and the pile body. Fifth, it can be effectively matched with the subway semi-cover excavation method, is simple to operate, and is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a schematic diagram of a temporary column pile foundation structure provided by an embodiment of the present invention.

[0050] Figure 2 It is a schematic diagram of the support disc cavity provided in an embodiment of the present invention.

[0051] Figure 3 It is a schematic diagram of the relationship between the small diameter steel pipe and the fixed structure provided in an embodiment of the present invention.

[0052] Figure 4 It is a schematic diagram of an open branch disc in a branch disc cavity provided by an embodiment of the present invention.

[0053] Figure 5It is a schematic diagram of a fixing structure provided by an embodiment of the present invention being fixed at an end of a small-diameter steel pipe.

[0054] Reference numerals:

[0055] 1-pile foundation; 2-enlarged head; 3-connector; 11-support plate; 12-reinforcement cage; 111-support plate skeleton; 112-small diameter steel pipe; 113-fixed structure; 121-channel steel bar; 1131-spring; 1132-locking steel bar; 1133-middle rod. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0057] In a first aspect, some embodiments of the present invention provide a temporary column pile foundation structure for a subway semi-covered excavation station, the structure comprising a pile foundation 1, an enlarged head 2, and a connector 3;

[0058] The enlarged head 2 is connected to the end of the pile foundation 1 away from the surface through a connector 3;

[0059] The pile foundation 1 comprises at least one branch plate cavity, and the branch plate cavity is used to place a branch plate 11;

[0060] The branch plate 11 includes a branch plate frame 111, and the branch plate frame 111 is used to improve the tensile strength of the branch plate cavity.

[0061] In some embodiments, the branch plate skeleton 111 is used to improve the tensile strength of the branch plate cavity as follows:

[0062] The support plate skeleton 111 is umbrella-shaped;

[0063] The support plate 11 includes a hollow small-diameter steel pipe 112 and a fixing structure 113; the fixing structure 113 is located inside the small-diameter steel pipe 112;

[0064] The fixing structure 113 includes a middle rod 1133;

[0065] The middle rod 1133 serves as the umbrella axis of the branch plate skeleton 111. One end of the branch plate skeleton 111 is hingedly connected to the small diameter steel pipe 112, and the other end of the branch plate skeleton 111 is hingedly connected to the middle rod 1133. When the middle rod 1133 moves upward, the branch plate skeleton 111 unfolds to form an umbrella shape. The umbrella-shaped branch plate skeleton 111 is fixed in the branch plate cavity to become a skeleton structure in the branch plate cavity.

[0066] In some embodiments, the branch plate frame 111 is fixed in the branch plate cavity as follows:

[0067] The fixing structure 113 further includes a locking steel bar 1132, and the middle rod 1133 vertically passes through the interior of the locking steel bar 1132 and is fixedly connected to the locking steel bar 1132;

[0068] The locking steel bar 1132 is provided with a spring 1131;

[0069] The upward movement of the middle rod 1133 drives the fixed structure 113 to leave the small diameter steel pipe 112. At the end of the small diameter steel pipe 112, the spring 1131 recovers its deformation, causing the locking steel bar 1132 to deform and be locked, so that the locking steel bar 1132 can no longer enter the small diameter steel pipe 112.

[0070] In some embodiments, as an example, the locking steel bar 1132 can be designed as a triangle, the bottom edge of the triangle of the locking steel bar 1132 is provided with a spring 1131, the middle rod 1133 penetrates the locking steel bar 1132, and the middle rod 1133 is fixedly connected to the corners of the triangle of the locking steel bar 1132. When the middle rod 1133 moves upward, the fixed structure 113 leaves the small diameter steel pipe 112. At the port of the small diameter steel pipe 112, the spring 1131 restores its deformation so that the length of the bottom edge of the locking steel bar 1132 is longer than the diameter of the port of the small diameter steel pipe 112, so that the locking steel bar 1132 can no longer enter the small diameter steel pipe 112.

[0071] In some embodiments, the shape of the locking steel bar 1132 can be further improved. In order to enhance the stability of the fixed connection between the middle rod 1133 and the locking steel bar 1132 so that the locking steel bar 1132 can be stably connected to the middle rod 1133 during movement, a hollow small pipe that can be fixedly connected to the middle rod can be provided at the corner of the triangle, and a hollow small pipe can also be provided at the base of the triangle. The hollow small pipe connected to the base is used to fix the locking steel bar 1132 in the small diameter steel pipe 112 so that the spring 1131 can be stably fixed to the base of the triangle.

[0072] In some embodiments, the pile foundation 1 further includes a steel cage 12; the steel cage 12 is provided with channel-shaped steel bars 121, and the channel-shaped steel bars 121 are fixedly connected to the small-diameter steel pipe 112 to fix the position of the small-diameter steel pipe 112 in the support plate cavity.

[0073] In some embodiments, the height of the connector 3 is 1m-2m.

[0074] In some embodiments, the pile foundation 1 is inserted into the connector 3 and fixedly connected to the connector 3 . The height of the pile foundation 1 inserted into the connector 3 is 0.5 m to 1 m.

[0075] In some embodiments, the radius of the enlarged head 2 is 1 to 3 times the radius of the pile foundation 1, and the height of the enlarged head is 2.5 m to 4.5 m.

[0076] In some embodiments, the shortest distance between the branch cavity and the ground surface is the sum of the foundation pit depth H1 and the branch cavity height H2; the shortest distance between adjacent branch cavities is 8 times the branch cavity width W; the shortest distance between the branch cavity and the end of the pile foundation 1 away from the ground surface is not less than the height of one branch cavity.

[0077] In some embodiments, the branch disc cavity is diamond-shaped.

[0078] In a second aspect, some embodiments of the present invention also provide a construction method for the temporary column pile foundation structure of the subway semi-covered excavation station, the method comprising:

[0079] Step S1: hammering the pile pipe into the plastic clay layer at the designed position, and whenever the pile pipe is hammered into 1m-2m, using a heavy hammer in the pile pipe to hammer the soil in the pile pipe out of the pile pipe, and the above steps are repeated;

[0080] Step S2: When the distance between the lower end of the pile pipe and the designed pile bottom differs by 3.5m-5.5m, the weight in the pile pipe is taken out, and waste building materials and quicklime are filled into the pile pipe, and the waste building materials and quicklime in the pile pipe are hammered out of the bottom of the pile pipe by the weight to form an enlarged head;

[0081] Step S3: adding dry hard concrete on the enlarged head through the pile pipe, and tamping with a heavy hammer so that the dry hard concrete can be filled in the enlarged head and a connecting body can be formed on the enlarged head;

[0082] Step S4: inserting the extrusion and expansion branch plate device into the pile pipe, taking out the pile pipe, and preliminarily forming the pile foundation; according to the design position of the branch plate cavity, at the design position, using the extrusion and expansion branch plate device to extrude the plastic clay layer around the extrusion and expansion branch plate device to form a plurality of diamond-shaped branch plate cavities;

[0083] Step S5: After the preparation of the branch plate cavity is completed, the extruded branch plate equipment is taken out, a steel cage is placed in the initially formed pile foundation, and the branch plate is fixed at the branch plate cavity, and finally concrete is poured to finally form a temporary column pile foundation structure.

[0084] In some embodiments, in step S2, the steps of filling the pile pipe with waste building materials and quicklime, and hammering the waste building materials and quicklime in the pile pipe out of the bottom of the pile pipe with a heavy hammer to form an enlarged head include:

[0085] The filled abandoned building materials and quicklime are rammed in layers, with each ramming forming a ramming thickness of 0.7m-0.9m, until the height of the enlarged head reaches 2.5m-4.5m.

[0086] In some embodiments, the height of the connector is 1m-2m.

[0087] In some embodiments, in step S5, the specific step of fixing the branch plate at the branch plate cavity includes:

[0088] A channel-shaped steel bar 121 is fixed on the steel cage at the support plate cavity;

[0089] The grooved steel bar 121 is used to fix the position of the support plate 11 in the support plate cavity. The hollow small-diameter steel pipe 112 in the support plate 11 is fixedly connected to the grooved steel bar 121.

[0090] The fixing structure 113 includes a locking steel bar 1132 and a middle rod 1133. The middle rod 1133 vertically passes through the interior of the locking steel bar 1132 and is fixedly connected to the locking steel bar 1132.

[0091] The locking steel bar 1132 is provided with a spring 1131;

[0092] By pulling the middle rod 1133 upward, the fixing structure 113 is driven to leave the small diameter steel pipe 112. At the end of the small diameter steel pipe 112, the spring 1131 recovers its deformation to cause the locking steel bar 1132 to deform and be locked, so that the locking steel bar 1132 can no longer enter the small diameter steel pipe 112.

[0093] The branch plate skeleton 111 is umbrella-shaped, and the middle rod 1133 serves as the umbrella axis of the branch plate skeleton. One end of the branch plate skeleton 111 is hingedly connected to the small diameter steel pipe 112, and the other end of the branch plate skeleton 111 is hingedly connected to the middle rod 1133. When the middle rod 1133 moves upward, the branch plate skeleton 111 unfolds to form an umbrella shape. The umbrella-shaped branch plate skeleton 111 is fixed in the branch plate cavity to become the skeleton structure in the branch plate cavity.

[0094] In some embodiments, the shortest distance between adjacent branch disc cavities is 8 times the width of the branch disc cavity.

[0095] The following is described in conjunction with specific embodiments:

[0096] Embodiment 1:

[0097] from Figure 1It can be found that the temporary column pile foundation structure provided by Example 1 of the present invention includes a pile foundation 1, an enlarged head 2, and a connector 3. The enlarged head 2 is connected to the end of the pile foundation 1 away from the surface through the connector 3; the pile foundation 1 is provided with at least one branch plate cavity, and the branch plate cavity is used to place a branch plate 11; the branch plate 11 includes a branch plate skeleton 111, and the branch plate skeleton 111 is used to improve the tensile strength of the branch plate cavity. The structure of the present invention is applied to plastic cohesive soil layers, and it is necessary to improve the friction resistance between the pile foundation and the soil layer, wherein the enlarged head can improve the bearing capacity of the end of the pile foundation, thereby facilitating the improvement of the end resistance of the bottom of the pile foundation, and the connector ensures the tight connection between the enlarged head and the pile foundation; a plurality of branch plate cavities are provided on the pile foundation, and the branch plate is located in the branch plate cavity. The branch plate skeleton can improve the tensile shear strength of the branch plate and improve the end resistance of the pile foundation within the range of the pile body. With the mutual cooperation between the above structures, the friction resistance between the pile foundation and the cohesive soil layer is improved.

[0098] exist Figure 2-Figure 3 It can be found that the support plate 11 includes a hollow small-diameter steel pipe 112 and a fixed structure 113; the fixed structure 113 is located in the small-diameter steel pipe 112, and the fixed structure 113 includes a middle rod 1133 and a locking steel bar 1132. The middle rod 1133 vertically passes through the interior of the locking steel bar 1132 and is fixedly connected to the locking steel bar 1132; a spring 1131 is provided in the locking steel bar 1132. When the fixed structure 113 is located in the small-diameter steel pipe 112, the spring is in a state of handling deformation and compression. Figure 4-Figure 5 In the figure, the branch plate skeleton 111 is in an umbrella shape, and the middle rod 1133 serves as the umbrella axis of the branch plate skeleton 111. One end of the branch plate skeleton 111 is hingedly connected to the small diameter steel pipe 112, and the other end of the branch plate skeleton 111 is hingedly connected to the middle rod 1133. When the middle rod 1133 moves upward, the branch plate skeleton 111 unfolds to form an umbrella shape. The umbrella-shaped branch plate skeleton 111 is fixed in the branch plate cavity to become the skeleton structure in the branch plate cavity.

[0099] First, in the present invention, the branch plate skeleton needs to be fully filled in the branch plate cavity to ensure that it becomes the skeleton structure of the branch plate cavity, so it is necessary to ensure that the branch plate can be fully deployed in the branch plate cavity. In the present invention, a steel cage needs to be set in the process of pile foundation formation. If the structure, deployment method and setting position of the branch plate skeleton are not appropriate, the deployment of the paper plate skeleton in the branch plate cavity will be hindered. Secondly, the pile foundation is formed by filling with concrete, and the branch plate must be stably fixed in the branch plate cavity, and the branch plate skeleton can also fully withstand the impact force from top to bottom during the concrete filling process. Therefore, the upward movement of the middle rod 1133 drives the fixed structure 113 to leave the small diameter steel pipe 112. At the port of the small diameter steel pipe 112, the spring 1131 restores the deformation to cause the locking steel bar 1132 to deform and be locked, so that the locking steel bar 1132 can no longer enter the small diameter steel pipe 112. It is ensured that the branch plate can stably exist in the branch plate cavity.

[0100] On this basis, the locking steel bar 1132 can be further designed as a triangle, and the triangular base of the locking steel bar 1132 is provided with a spring 1131, and the middle rod 1133 penetrates the locking steel bar 1132, and the middle rod 1133 is fixedly connected to the corners of the triangle of the locking steel bar 1132. When the middle rod 1133 moves upward, the fixed structure 113 leaves the small diameter steel pipe 112. At the port of the small diameter steel pipe 112, the spring 1131 restores its deformation to make the length of the bottom side of the locking steel bar 1132 longer than the diameter of the port of the small diameter steel pipe 112, so that the locking steel bar 1132 can no longer enter the small diameter steel pipe 112.

[0101] Furthermore, the locking steel bar 1132 can be designed as a triangle (such as Figure 2 As shown in the figure), the triangular bottom side of the locking steel bar 1132 is provided with a spring 1131, and the middle rod 1133 penetrates the locking steel bar 1132. The middle rod 1133 is fixedly connected to the corner of the triangle of the locking steel bar 1132. When the middle rod 1133 moves upward, the fixed structure 113 leaves the small diameter steel pipe 112. At the port of the small diameter steel pipe 112, the spring 1131 recovers its deformation so that the length of the bottom side of the locking steel bar 1132 is longer than the diameter of the port of the small diameter steel pipe 112, so that the locking steel bar 1132 can no longer enter the small diameter steel pipe 112. The stability of the fixed connection between the middle rod 1133 and the locking steel bar 1132 can be further improved, so that the locking steel bar 1132 can be stably connected to the middle rod 1133 during the movement of the middle rod 1133. A hollow small pipe that can be fixedly connected to the middle rod can be set at the corner of the triangle, and a hollow small pipe can also be set at the base of the triangle. The hollow small pipe connected to the base is used to fix the locking steel bar 1132 in the small diameter steel pipe 112, so that the spring 1131 can be stably fixed on the base of the triangle.

[0102] exist Figure 2 and Figure 4 It is found that the pile foundation 1 also includes a steel cage 12; the steel cage 12 is provided with a groove steel bar 121, and the groove steel bar 121 is fixedly connected to the small diameter steel pipe 112 to fix the position of the small diameter steel pipe 112 in the support plate cavity. The O point of the support plate skeleton is determined as the fixed point, and A, B, and C are the movable hinge points. The O points of BO and OC are hinged and fixed to a section of small diameter steel pipe, and the steel pipe is fixed and welded to the main bars of the outer steel cage through the groove steel bar. According to the size and angle of the support plate, the length and diameter of each rod of the support plate steel frame are determined.

[0103] Figure 1 It is also disclosed that the height of the connector 3 is 1m-2m. The pile foundation 1 is inserted into the connector 3 and fixedly connected to the connector 3, and the height of the pile foundation 1 inserted into the connector 3 is 0.5m-1m. The radius of the enlarged head 2 is 1-3 times the radius of the pile foundation 1, and the height of the enlarged head is 2.5m-4.5m. The shortest distance between the branch plate cavity and the ground surface is the sum of the foundation pit depth H1 and the branch plate cavity height H2; the shortest distance between adjacent branch plate cavities is 8 times the branch plate cavity width W; the shortest distance between the branch plate cavity and the end of the pile foundation 1 away from the ground surface is not less than the height of one branch plate cavity. The branch plate cavity can be rhombus-shaped. The setting between these parameters further improves the friction resistance of the pile foundation.

[0104] The structure of the present invention is achieved by the following method:

[0105] (1) Use a 6t columnar hammer to ram the ground to form a hole, and use a vibrating hammer to sink the pile pipe into the hole. Hammer and vibrate to pressurize the pipe. The diameter and length of the pile pipe are consistent with the designed pile diameter and the construction pile length. The designed pile diameter is 1000mm. Every time the pile pipe sinks 1 meter, a heavy hammer is used to hammer the soil out of the pile pipe. When the bottom of the pile pipe is 4.5m away from the designed pile bottom, broken bricks, concrete blocks and other waste building materials and quicklime blocks are filled in the pile bottom through the pile pipe in batches. The quicklime absorbs water and expands. A heavy hammer is used to ram the filling materials at the pile bottom in layers. The thickness of each layer is 0.8m. A mixed material reinforcement enlarged head with a larger diameter than the pile (3m) and a depth of about 3.5m can be formed at the bottom of the pile, which can greatly improve the bearing capacity of the pile end.

[0106] Fill an appropriate amount of dry hard concrete above the enlarged head and tamp it with a heavy hammer to form a 1m high connector. The diameter of the connector should be consistent with that of the enlarged head.

[0107] (2) Use the extrusion and expansion equipment to construct the support plate and expand the hole wall on the side wall of the drill hole

[0108] Raise the heavy hammer, place a special branch plate extrusion and expansion machine in the pile pipe, lift the pile pipe to the top of the designed branch plate cavity while vibrating, and squeeze the soil at each branch plate cavity position from bottom to top to expand it into a branch plate cavity.

[0109] (3) Umbrella-shaped connection, movable and fixing device between the steel cage and the support plate

[0110] A steel cage is made, and grooved steel bars are arranged inside the cage. The grooved steel bars are fixed in the support cavity, and the grooved steel bars are used to fix the relative positions of the small and medium diameter steel pipes in the support cavity. The support frame is shaped like an upside-down umbrella and can be retracted and opened. During the lowering of the steel cage, the support frame is in a retracted state. When the support frame is lowered to the pre-extruded support cavity position, the bottom of the steel cage is just embedded in the pit reserved at the top of the column hammer expansion connector, fixing the outer steel cage and lifting the center rod reserved on the ground. The support frame is opened, and the spring locking device in the center of the frame is turned on. The support frame remains open, and the pile body concrete is poured to form a bottom-expanded steel frame support cast-in-place pile.

[0111] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present application. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0112] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A temporary column pile foundation structure for a semi-covered subway station, characterized in that: The structure comprises a pile foundation (1), an enlarged head (2), and a connector (3); The end of the pile foundation (1) away from the ground surface is connected to the enlarged head (2) through a connector (3); The pile foundation (1) comprises at least one branch plate cavity, wherein the branch plate cavity is used to place a branch plate (11); The branch plate (11) comprises a branch plate frame (111), and the branch plate frame (111) is used to improve the tensile strength of the branch plate cavity; The branch plate frame (111) is used to improve the tensile strength of the branch plate cavity. Specifically: The support plate skeleton (111) is umbrella-shaped; The support plate (11) comprises a hollow small-diameter steel pipe (112) and a fixing structure (113); the fixing structure (113) is located inside the small-diameter steel pipe (112); The fixing structure (113) comprises a middle rod (1133); The middle rod (1133) serves as the umbrella axis of the support plate frame (111); one end of the support plate frame (111) is hingedly connected to the small diameter steel pipe (112); the other end of the support plate frame (111) is hingedly connected to the middle rod (1133); when the middle rod (1133) moves upward, the support plate frame (111) spreads out in all directions to form an umbrella shape; the umbrella-shaped support plate frame (111) is fixed in the support plate cavity to form a skeleton structure in the support plate cavity; The support plate frame (111) is fixed in the support plate cavity as follows: The fixing structure (113) further comprises a locking steel bar (1132), wherein the middle rod (1133) vertically passes through the interior of the locking steel bar (1132) and is fixedly connected to the locking steel bar (1132); The locking steel bar (1132) is provided with a spring (1131); The fixing structure (113) is driven to leave the small diameter steel pipe (112) by the upward movement of the middle rod (1133). At the end of the small diameter steel pipe (112), the spring (1131) recovers its deformation, causing the locking steel bar (1132) to deform and be locked, so that the locking steel bar (1132) cannot enter the small diameter steel pipe (112) again. The pile foundation (1) further comprises a steel cage (12); a channel-shaped steel bar (121) is arranged in the steel cage (12); the channel-shaped steel bar (121) is fixedly connected to the small-diameter steel pipe (112) and is used to fix the position of the small-diameter steel pipe (112) in the support plate cavity.

2. The temporary column pile foundation structure for a subway semi-covered station according to claim 1 is characterized in that: The height of the connector (3) is 1m-2m; The pile foundation (1) is inserted into the connector (3) and fixedly connected to the connector (3), and the height of the pile foundation (1) inserted into the connector (3) is 0.5m-1m; The radius of the enlarged head (2) is 1 to 3 times the radius of the pile foundation (1), and the height of the enlarged head (2) is 2.5 m to 4.5 m.

3. The temporary column pile foundation structure for a subway semi-covered station according to claim 1 is characterized in that: The shortest distance between the branch cavity and the ground surface is the sum of the foundation pit depth H1 and the branch cavity height H2; the shortest distance between adjacent branch cavities is 8 times the branch cavity width W; and the shortest distance between the branch cavity and the end of the pile foundation (1) away from the ground surface is not less than the height of one branch cavity.

4. The construction method of the temporary column pile foundation structure of the subway semi-covered station according to any one of claims 1 to 3, characterized in that: The method comprises: Step S1: hammering the pile pipe into the plastic clay layer at the designed position, and whenever the pile pipe is hammered into 1m-2m, using a heavy hammer in the pile pipe to hammer the soil in the pile pipe out of the pile pipe, and the above steps are repeated; Step S2: When the distance between the lower end of the pile pipe and the designed pile bottom differs by 3.5m-5.5m, the weight in the pile pipe is taken out, and waste building materials and quicklime are filled into the pile pipe, and the waste building materials and quicklime in the pile pipe are hammered out of the bottom of the pile pipe by the weight to form an enlarged head; Step S3: adding dry hard concrete on the enlarged head through the pile pipe, and tamping with a heavy hammer so that the dry hard concrete can be filled in the enlarged head and a connecting body can be formed on the enlarged head; Step S4: inserting the extrusion and expansion branch plate device into the pile pipe, taking out the pile pipe, and preliminarily forming the pile foundation; according to the design position of the branch plate cavity, at the design position, using the extrusion and expansion branch plate device to extrude the plastic clay layer around the extrusion and expansion branch plate device to form a plurality of diamond-shaped branch plate cavities; Step S5: After the preparation of the branch plate cavity is completed, the extruded branch plate equipment is taken out, a steel cage is placed in the initially formed pile foundation, and the branch plate is fixed at the branch plate cavity, and finally concrete is poured to finally form a temporary column pile foundation structure.

5. The construction method according to claim 4, characterized in that: In step S2, the steps of filling the pile pipe with waste building materials and quicklime, and hammering the waste building materials and quicklime in the pile pipe out of the bottom of the pile pipe with a heavy hammer to form an enlarged head include: The waste building materials and quicklime filled are tamped in layers, with each tamping forming a tamping thickness of 0.7m-0.9m, until the height of the enlarged head reaches 2.5m-4.5m; The height of the connector is 1m-2m.

6. The construction method according to claim 5, characterized in that: In step S5, the specific steps of fixing the branch plate at the branch plate cavity include: Channel-shaped steel bars are fixed on the steel cage at the support plate cavity; The grooved steel bar is used to fix the position of the support plate in the support plate cavity. The hollow small-diameter steel pipe in the support plate is fixedly connected to the grooved steel bar. The fixing structure includes a locking steel bar and a middle rod, wherein the middle rod vertically passes through the interior of the locking steel bar and is fixedly connected to the locking steel bar; The locking steel bar is provided with a spring; By pulling the middle rod upward, the fixed structure is driven to leave the small diameter steel pipe. At the end of the small diameter steel pipe, the spring recovers and deforms the locking steel bar, causing it to be deformed and locked, so that the locking steel bar can no longer enter the small diameter steel pipe. The branch plate skeleton is umbrella-shaped, and the middle rod serves as the umbrella axis of the branch plate skeleton. One end of the branch plate skeleton is hingedly connected to a small-diameter steel pipe, and the other end of the branch plate skeleton is hingedly connected to the middle rod. When the middle rod moves upward, the branch plate skeleton unfolds to form an umbrella shape. The umbrella-shaped branch plate skeleton is fixed in the branch plate cavity to become the skeleton structure in the branch plate cavity.

7. The construction method according to claim 4, characterized in that: The shortest distance between adjacent branch disc cavities is 8 times the width of the branch disc cavity.

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