Temporary supporting device for foundation pit

Abstract

The utility model provides a foundation pit temporary supporting device which comprises a concrete layer laid on the slope surface of a foundation pit, drill holes are formed in the concrete layer and the slope of the foundation pit, anchor rods are inserted into the drill holes and are not inserted into the bottoms of the drill holes, the outer surface of each anchor rod is fixedly connected with a plurality of sets of positioning pieces, at least three positioning pieces form one set, and the positioning pieces are connected with the concrete layer. The surfaces of the positioning pieces are movably connected with the inner wall of the drill hole, and a guide ring is fixedly connected between the two positioning pieces in each set. The anchor rod positioning device has the advantages that the anchor rod is kept at the central position in a drill hole, the arc-shaped guide rings are welded between each group of positioning pieces, and the inner diameter of each guide ring is larger than the outer diameter of a grouting pipe. The guide rings are arranged in the length direction of the anchor rod at intervals of 1.2 m to form a continuous guide channel. The guide ring ensures that the grouting pipe moves along the axis of the anchor rod all the time, grout is diffused outwards from the center of a drill hole, and a uniform cylindrical grouting body is formed. And the slurry wrapping thickness deviation is small, the forming uniformity of the slurry in the hole is better, and the grouting hollowing rate is low.

Description

A temporary support device for foundation pit Technical Field

[0001] This utility model relates to the field of foundation pit support technology, and in particular to a temporary foundation pit support device. Background Technology

[0002] Foundation pit support engineering is a crucial part of civil engineering construction, and its stability directly affects construction safety and the safety of the surrounding environment. In complex conditions such as soft soil layers, high groundwater levels, or adjacent buildings or structures, traditional support systems often face technical bottlenecks such as insufficient anchoring force, uneven grout distribution, and poor structural integrity.

[0003] In existing technologies, the common support method is to combine drilled grouting anchors with shotcrete surface layers. However, there are significant defects in the implementation process: First, the anchor positioning lacks an effective guiding device, and eccentricity is prone to occur during construction, resulting in uneven grout coating thickness. Actual measurement data shows that when the eccentricity exceeds 5mm, the pull-out resistance of the anchor body decreases by 15%-20%. Second, the grouting pipe is inserted in a free-suspension manner, and pipe body deviation is prone to occur during the pipe pulling process, causing the radial distribution dispersion coefficient of grout to exceed 0.35, forming local void defects. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the aforementioned technical defects.

[0005] Therefore, one objective of this utility model is to propose a temporary support device for foundation pits to solve the problems mentioned in the background art and overcome the shortcomings of the existing technology.

[0006] To achieve the above objectives, one embodiment of the present invention provides a temporary support device for a foundation pit, including a concrete layer laid on the slope of the foundation pit, with boreholes drilled in the concrete layer and the foundation pit slope, and anchor rods inserted into the boreholes, wherein the anchor rods are not inserted to the bottom of the boreholes;

[0007] The outer surface of the anchor rod is fixedly connected with several sets of positioning plates, with at least three positioning plates per set, and the surface of the positioning plates is movably connected to the inner wall of the borehole.

[0008] A guide ring is fixedly connected between two of the positioning pieces in each group, and the guide ring is arc-shaped.

[0009] The guide ring is internally connected to a grouting pipe, which is always movably connected to the surface of the anchor bolt.

[0010] The surface of the concrete layer is covered with several panels, and the surface of the panels is pressed with a reinforcing mesh;

[0011] The reinforcing mesh is formed by the intersection of several horizontal and vertical reinforcing bars, and the intersection points of the reinforcing mesh are fixedly connected to the ends of the anchor rods.

[0012] Preferably, in any of the above schemes, the thickness of the concrete layer is 4-5 cm, the diameter of the drill hole is larger than the diameter of the anchor rod, and cement mortar is injected into the drill hole.

[0013] The above-mentioned technical solution: This foundation pit support device aims to prevent foundation pit collapse and landslide.

[0014] This support device includes the main structures such as concrete layer, boreholes, anchor bolts, grouting pipes, panels, and reinforcement mesh. Cement grout also needs to be steadily injected into the boreholes of the foundation pit slope and concrete layer, all the way to the surface of the concrete layer.

[0015] Preferably, in any of the above embodiments, the positioning piece is arc-shaped, the positioning piece is welded to the surface of the anchor rod, and the positioning piece centers the anchor rod in the borehole.

[0016] The construction process of this support device is as follows: initial spraying of concrete on the surface of the pit slope to form a concrete layer, stabilizing the slope first, and then attaching a panel to the concrete layer surface with mortar. This panel can be understood as the protective layer and working surface of this support device.

[0017] Drilling equipment is used to create a hole with a certain angle. The hole is cleaned and an anchor rod is inserted. The positioning plate on the surface of the anchor rod is movably connected to the inner wall of the hole to ensure that the anchor rod is centered in the hole. At the same time as inserting the anchor rod, the grouting pipe is inserted. The grouting pipe is inserted along the guide ring. The grouting pipe is always parallel to the anchor rod when entering and exiting the hole. The diameter of the anchor rod is 16-32mm. The top of the grouting pipe is connected to the grouting equipment to inject grout into the hole. The grout slowly rises from the bottom of the hole. At the same time, the grouting pipe is slowly pulled out. The design of the guide ring allows the grouting pipe to be pulled out stably. The grout that is just output is also closer to the center of the hole and can smoothly fill the hole until it is full.

[0018] Subsequently, a reinforcing mesh is installed on the panel surface, and the intersections of the reinforcing mesh are welded to the exposed ends of the anchor rods.

[0019] Preferably, in any of the above schemes, the guide ring is welded to the positioning plate, and the length of the grouting pipe is less than the length of the anchor rod.

[0020] The above technical solution is adopted. The system composition of this device is as follows:

[0021] Concrete layer and drilling system: A 4-5cm thick concrete layer is sprayed onto the slope of the foundation pit as the initial support surface layer, and a geological drilling rig is used to drill holes with a diameter larger than that of the anchor bolts.

[0022] The anchor bolt positioning system uses threaded steel with a diameter of 16-32mm, and welds at least three sets of positioning plates to its surface. The positioning plates are arc-shaped steel plates distributed in a 120° circle to ensure that the anchor bolt remains centered in the drilled hole.

[0023] Guide ring guiding mechanism: Arc-shaped guide rings are welded between each group of positioning plates. The inner diameter of the guide ring is 2-3mm larger than the outer diameter of the grouting pipe. Guide rings 5 ​​are set at 1.2m intervals along the length of the anchor rod to form a continuous guiding channel.

[0024] The dynamic grouting system uses 20mm diameter plastic grouting pipes, with the pipe length being 0.8-1.2m shorter than the anchor bolt. During grouting, the grouting pipe moves parallel to the anchor bolt via guide rings, and the pipe pulling speed is controlled at 0.5m / min.

[0025] The composite support surface layer consists of precast concrete panels bonded to the concrete layer surface with M15 cement mortar. A reinforcing mesh composed of Φ10 steel bars is laid on the panel surface, and the intersections of the reinforcing mesh are welded to the ends of the anchor rods to form an integral load-bearing system.

[0026] Preferably, in any of the above solutions, the grouting pipe is made of plastic and is always located close to the center of the anchor bolt.

[0027] The core design of this device is as follows: the guide ring ensures that the grouting pipe always moves along the anchor bolt axis, and the grout diffuses outward from the center of the borehole to form a uniform cylindrical grout body. This results in minimal grout coating thickness deviation, better grout uniformity in the hole, and a low grout void rate.

[0028] Preferably, in any of the above embodiments, the panel is a precast concrete slab, which is laid on the surface of the concrete layer with cement mortar.

[0029] Preferably, in any of the above schemes, the intersection points of the reinforcing mesh are welded to the ends of the anchor rods.

[0030] Compared with the prior art, the advantages and beneficial effects of this utility model are as follows:

[0031] The temporary support device for this foundation pit uses threaded steel anchor bolts with at least three sets of positioning plates welded to their surfaces. These positioning plates are arc-shaped steel plates distributed in a 120° circle to ensure the anchor bolt remains centered in the borehole. Arc-shaped guide rings are welded between each set of positioning plates; the inner diameter of the guide rings is larger than the outer diameter of the grouting pipe. A set of guide rings is placed every 1.2m along the length of the anchor bolt, forming a continuous guiding channel. The guide rings ensure that the grouting pipe always moves along the anchor bolt axis, allowing the grout to diffuse outward from the center of the borehole, forming a uniform cylindrical grout body. This results in minimal grout coating thickness deviation, better grout uniformity in the hole, and a low grout void rate.

[0032] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0034] Figure 1 is a structural schematic diagram of this utility model from a first perspective;

[0035] Figure 2 is a structural schematic diagram of this utility model from a second perspective;

[0036] Figure 3 is a schematic diagram of the structure in the drilling process of this utility model;

[0037] Figure 4 is an enlarged structural schematic diagram of point A in Figure 2 of this utility model.

[0038] In the diagram: 1-Concrete layer, 2-Drill hole, 3-Anchor bolt, 4-Positioning plate, 5-Guide ring, 6-Grouting pipe, 7-Panel, 8-Reinforcing mesh. Detailed Implementation

[0039] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0040] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0041] As shown in Figures 1-4, the temporary support device for this foundation pit includes a concrete layer 1 laid on the slope of the foundation pit, and boreholes 2 are drilled in the concrete layer 1 and the slope of the foundation pit. Anchor rods 3 are inserted into the boreholes 2, but the anchor rods 3 are not inserted to the bottom of the boreholes 2.

[0042] Several sets of positioning plates 4 are fixedly connected to the outer surface of the anchor rod 3. There are at least three positioning plates 4 in a group, and the surface of the positioning plates 4 is movably connected to the inner wall of the borehole 2.

[0043] A guide ring 5 is fixedly connected between two positioning pieces 4 in each group. The guide ring 5 is arc-shaped.

[0044] The guide ring 5 is internally connected to a grouting pipe 6, which is always movably connected to the surface of the anchor rod 3.

[0045] Several panels 7 are laid on the surface of the concrete layer 1, and a reinforcing mesh 8 is pressed onto the surface of the panels 7;

[0046] The reinforcing mesh 8 is composed of several intersecting horizontal and vertical reinforcing bars, and the intersection points of the reinforcing mesh 8 are fixedly connected to the ends of the anchor rods 3.

[0047] Example 1: The thickness of the concrete layer 1 is 4-5 cm. The diameter of the drill hole 2 is larger than the diameter of the anchor rod 3. Cement mortar is injected into the drill hole 2. The positioning plate 4 is arc-shaped and welded to the surface of the anchor rod 3, centered the anchor rod 3 in the drill hole 2. The guide ring 5 is welded to the positioning plate 4, and the length of the grouting pipe 6 is less than the length of the anchor rod 3.

[0048] Example 2: The purpose of this foundation pit support device is to prevent foundation pit collapse and landslide.

[0049] This support device includes the main structures such as concrete layer 1, borehole 2, anchor bolt 3, grouting pipe 6, panel 7, and reinforcement mesh 8. Cement grout needs to be steadily injected into the borehole 2 of the foundation pit slope and concrete layer 1 until it reaches the surface of concrete layer 1.

[0050] The construction process of this support device is as follows: the surface of the pit slope is initially sprayed with concrete to form a concrete layer 1, which stabilizes the slope. Then, a panel 7 is attached to the surface of the concrete layer 1 with mortar. This panel 7 can be understood as the protective layer and working surface of this support device.

[0051] Drilling equipment is used to create a hole 2 with a certain angle. The hole 2 is cleaned and an anchor rod 3 is inserted into it. The positioning plate 4 on the surface of the anchor rod 3 is movably connected to the inner wall of the hole to ensure that the anchor rod 3 is centered in the hole. At the same time as inserting the anchor rod 3, the grouting pipe 6 is inserted. The grouting pipe 6 is inserted along the guide ring 5. The grouting pipe 6 is always parallel to the anchor rod 3 when it is inserted and pulled out. The diameter of the anchor rod 3 is 16-32mm. The top of the grouting pipe 6 is connected to the grouting equipment to inject grout into the hole. The grout slowly rises from the bottom of the hole. At the same time, the grouting pipe 6 is slowly pulled out. The design of the guide ring 5 makes the grouting pipe 6 stable when pulled out. The grout that is just output is also closer to the center of the hole and can smoothly fill the hole until it is full.

[0052] Subsequently, a reinforcing mesh 8 is installed on the surface of panel 7, and the intersections of the reinforcing mesh 8 are welded to the exposed ends of anchor rods 3. The grouting pipe 6 is made of plastic and is always positioned close to the center of anchor rods 3. Panel 7 is specifically a precast concrete slab, which is laid on the surface of concrete layer 1 with cement mortar. The intersections of the reinforcing mesh 8 are welded to the ends of anchor rods 3.

[0053] Example 3: System composition of this device:

[0054] Concrete layer 1 and borehole 2 system: A 4-5cm thick concrete layer 1 is sprayed on the slope of the foundation pit to form an initial support surface layer, and a geological drilling rig is used to drill borehole 2 with a diameter larger than that of the anchor bolt 3;

[0055] The anchor bolt 3 positioning system is constructed using threaded steel with a diameter of 16-32mm, and at least three sets of positioning plates 4 are welded to its surface. The positioning plates 4 are arc-shaped steel plates distributed in a 120° circle to ensure that the anchor bolt 3 remains centered in the drilled hole 2.

[0056] Guide ring 5 guiding mechanism: Arc-shaped guide rings 5 ​​are welded between each group of positioning plates 4. The inner diameter of the guide ring 5 is 2-3mm larger than the outer diameter of the grouting pipe 6. A set of guide rings 5 ​​is set every 1.2m along the length of the anchor rod 3 to form a continuous guiding channel.

[0057] The dynamic grouting system uses a 20mm diameter plastic grouting pipe 6, which is 0.8-1.2m shorter than the anchor rod 3. During grouting, the grouting pipe 6 is kept parallel to the anchor rod 3 by the guide ring 5, and the pipe pulling speed is controlled at 0.5m / min.

[0058] The composite support surface layer consists of precast concrete panels 7 bonded to the surface of concrete layer 1 with M15 cement mortar. A reinforcing mesh 8 composed of Φ10 steel bars is laid on the surface of panel 7. The intersections of the reinforcing mesh 8 are welded to the ends of anchor rods 3 to form an integral load-bearing system.

[0059] The working principle of this utility model is as follows:

[0060] Initial slope spraying: C20 fine aggregate concrete is sprayed using a wet spraying method to form concrete layer 1, with the thickness strictly controlled at 45±5mm. Curing is carried out within 6 hours after spraying.

[0061] Drilling: Use an XY-2 drilling rig to drill holes 2 with a diameter of 80-100mm. The hole depth should be 0.3m greater than the length of the anchor bolt 3. After drilling, use high-pressure air to clean the hole to ensure the hole wall is clean.

[0062] Anchor bolt installation: Slowly insert the prefabricated anchor bolt 3 into the drill hole 2. The positioning plate 4 will contact the hole wall to generate frictional resistance. Stop when the anchor bolt 3 is inserted to the designed depth (0.5m from the bottom of the hole). At this time, leave a 200mm welding length for the exposed end.

[0063] Grouting operation: The grouting pipe 6 is inserted through the guide ring 5 to a position 0.2m above the bottom of the hole. The grouting pump is started to inject cement grout with a water-cement ratio of 0.45 at a pressure of 0.4-0.6MPa. Simultaneously, the grouting pipe 6 is pulled back at a speed of 0.3m / min to ensure that the grout continuously fills from the bottom of the hole upwards.

[0064] Surface layer construction: After grouting and curing for 24 hours, install 600×600×50mm precast concrete panels 7 using the grouting method, with mortar fullness ≥95%. A 10mm expansion joint is reserved at the joints of panel 7.

[0065] Reinforcement mesh construction: Φ10@150×150 steel mesh is laid on the surface of panel 7 as reinforcement mesh 8. All intersections are welded to the exposed ends of anchor rods 3 using carbon dioxide shielded welding, and the weld length is ≥50mm.

[0066] Compared with the prior art, the present invention has the following advantages:

[0067] The temporary support device for this foundation pit uses threaded steel anchor bolts 3, with at least three sets of positioning plates 4 welded to their surface. The positioning plates 4 are arc-shaped steel plates distributed in a 120° circumference, ensuring the anchor bolt 3 remains centered within the borehole 2. Arc-shaped guide rings 5 ​​are welded between each set of positioning plates 4, with the inner diameter of the guide rings 5 ​​being 2-3 mm larger than the outer diameter of the grouting pipe 6. Guide rings 5 ​​are installed at 1.2 m intervals along the length of the anchor bolt 3, forming a continuous guiding channel. The guide rings 5 ​​ensure that the grouting pipe 6 always moves along the axis of the anchor bolt 3, allowing the grout to diffuse outward from the center of the borehole 2, forming a uniform cylindrical grout body. This results in minimal grout coating thickness deviation, better grout uniformity in the hole, and a low grout void rate.

Claims

1. A temporary support device for foundation pits, characterized in that, The structure includes a concrete layer laid on the slope of the foundation pit, with boreholes drilled in the concrete layer and the foundation pit slope. Anchor rods are inserted into the boreholes, but not to the bottom of the boreholes. Several sets of positioning plates are fixedly connected to the outer surface of the anchor rods, with at least three positioning plates per set. The surface of the positioning plates is movably connected to the inner wall of the borehole. A guide ring, which is arc-shaped, is fixedly connected between two positioning plates in each set. A grouting pipe is movably connected inside the guide ring, and the grouting pipe is always movably connected to the surface of the anchor rod. Several panels are laid on the surface of the concrete layer, and a reinforcing mesh is pressed onto the surface of the panels. The reinforcing mesh is formed by the intersection of several horizontal and vertical reinforcing bars, and the intersection points of the reinforcing mesh are fixedly connected to the ends of the anchor rods.

2. The temporary support device for foundation pits as described in claim 1, characterized in that: The thickness of the concrete layer is 4-5 cm, the diameter of the drilled hole is larger than the diameter of the anchor rod, and cement mortar is injected into the drilled hole.

3. The temporary support device for foundation pits as described in claim 2, characterized in that: The positioning plate is arc-shaped and is welded to the surface of the anchor rod, thereby centering the anchor rod in the borehole.

4. The temporary support device for foundation pits as described in claim 3, characterized in that: The guide ring is welded to the positioning plate, and the length of the grouting pipe is less than the length of the anchor rod.

5. A temporary support device for foundation pits as described in claim 4, characterized in that: The grouting pipe is made of plastic and is always located close to the center of the anchor rod.

6. The temporary support device for foundation pits as described in claim 5, characterized in that: The panel is specifically a precast concrete slab, which is laid on the surface of the concrete layer with cement mortar.

7. A temporary support device for foundation pits as described in claim 6, characterized in that: The intersections of the reinforcing mesh are welded to the ends of the anchor rods.

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