Communication tower anti-settlement foundation suitable for water-permeable soil layer and on-site pouring method thereof

Abstract

The application discloses a communication tower anti-settlement foundation suitable for water-permeable soil layers and a site pouring method thereof, and relates to the technical field of communication tower construction. The foundation comprises a foundation pit, which is vertically dug from the ground to a soft soil layer line L, penetrates a surface hard soil to reach the soft soil layer, a bell bottom pit, which is continuously dug downward at the bottom of the foundation pit to a depth of not less than 2m, and the diameter of the bell bottom pit is greater than that of the foundation pit, forming a cross-section structure with a narrow upper part and a wide lower part, a dynamic compaction expansion area, which is located at the bottom of the bell bottom pit. The application forms the dynamic compaction expansion area through the cross-section structure with the narrow upper part and the wide lower part, greatly increases the bearing area of the bottom of the foundation compared with the cross-section of the foundation pit, significantly improves the compactness of the deep soil body at the bottom of the bell bottom pit, and coaxially arranges a peripheral water-blocking ring pit outside the foundation pit. The annular water-blocking structure can effectively block the penetration of external seepage water to the direction of the foundation pit, and reduces the weakening of the bearing capacity of the foundation caused by the erosion of underground water.

Description

Technical Field

[0001] This invention relates to the field of communication tower construction technology, specifically to an anti-settlement foundation for communication towers suitable for permeable soil layers and its on-site pouring method. Background Technology

[0002] Currently, communication tower foundations mostly adopt conventional independent foundations or pile foundations. In areas with permeable soil layers, due to the high water content, low bearing capacity, and high compressibility of the soil, conventional foundations are prone to uneven settlement, leading to tilting or even collapse of the communication tower. Existing solutions typically only increase the bearing capacity by increasing the foundation depth or expanding the foundation base area, but this method has limited effectiveness in permeable soil layers and has obvious technical shortcomings.

[0003] Firstly, conventional independent conical foundations and small enlarged-base piles only undergo simple bottom diameter enlargement treatment, resulting in a limited effective bearing area at the bottom. They do not penetrate the surface hard soil to the soft soil layer for deep compaction reinforcement. The vertical load of the tower body is concentrated on the local soil, and groundwater from the perimeter of the site can flow around the sidewall of the foundation pit and continuously seep into the foundation, continuously softening the foundation soil, and the settlement problem worsens year by year.

[0004] Secondly, although large-area integral raft foundations can disperse vertical loads, they cannot block the seepage of deep groundwater by relying solely on the surface waterproof coating. They also have weak horizontal wind resistance and anti-slip performance, and the foundation is prone to lateral displacement and concrete through cracks under strong wind loads.

[0005] Furthermore, conventional single-pile enlarged-base foundations rely solely on increasing the vertical bearing capacity by expanding the pile bottom diameter, resulting in poor lateral soil constraint. Once the bearing capacity of the foundation soil decreases due to water seepage, without an additional support system to prevent this, unilateral settlement of the foundation and tilting of the tower are highly likely to occur.

[0006] Therefore, in view of this situation, the present invention proposes a novel anti-settlement foundation for communication towers and provides a corresponding on-site pouring method to improve the above-mentioned problems. Summary of the Invention

[0007] The purpose of this invention is to provide a settlement-resistant foundation for communication towers suitable for permeable soil layers and a method for on-site casting thereof, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a settlement-resistant foundation for communication towers suitable for permeable soil layers, comprising:

[0009] The foundation pit is excavated vertically downwards from the ground to the soft soil layer line L, penetrating the surface hard soil to reach the soft soil layer.

[0010] The bell-bottom pit is excavated to a depth of not less than 2m from the bottom of the foundation pit, and the diameter of the bell-bottom pit is greater than the diameter of the foundation pit, forming a cross-sectional structure that is narrow at the top and wide at the bottom.

[0011] The high-impact expansion zone is located at the bottom of the bell-shaped pit and is formed by high-impact compaction downwards.

[0012] The outer water-blocking ring pit is coaxially arranged on the outside of the foundation pit, and is excavated downwards in a ring shape from the ground to surround the foundation pit;

[0013] The grouting channel is excavated between the foundation pit and the outer water-blocking ring pit, connecting the foundation pit and the outer water-blocking ring pit;

[0014] The first grouting layer is applied to fill the foundation pit and the bell-bottom pit.

[0015] The second grouting layer is set above the first grouting layer and extends from the top of the first grouting layer to the top height inside the outer water-blocking ring pit;

[0016] A floating slab layer is laid on top of the second grouting layer and extends to the ground;

[0017] A composite concrete slab layer is laid on top of the floating slab layer, and the bonding strength between the composite concrete slab layer and the floating slab layer is enhanced by anchor bolts.

[0018] The communication tower foundation base is located above the composite concrete slab.

[0019] Further, the main reinforcing cage and supporting piles are installed in the foundation pit. The grouting height extends from the dynamic compaction expansion zone to the grouting channel, while maintaining the height above the grouting channel. Concrete extends from the inside of the foundation pit to the outer water-blocking ring pit through the grouting channel, so that the concrete in the foundation pit and the concrete in the outer water-blocking ring pit are integrated.

[0020] Furthermore, regarding this scheme, the minimum distance between the outer water-blocking ring pit and the foundation pit is greater than 5m, and the top height inside the outer water-blocking ring pit is 50cm lower than the ground height.

[0021] Further, the dynamic compaction extension zone is a dense soil layer area formed after being treated by a ton-class dynamic compaction machine. The dynamic compaction extends the depth of the bell pit downward by 20cm-200cm.

[0022] Furthermore, the grouting channel is equipped with a side steel reinforcement cage, which is arranged along the channel direction of the grouting channel and connected to the main steel reinforcement cage to form an integral steel reinforcement skeleton.

[0023] Furthermore, the main reinforcing cage and the supporting pile are enclosed within the first grouting layer and the second grouting layer.

[0024] Further, the floating plate layer consists of a steel mesh and floating plates, with the steel mesh laid on the top surface of the second grouting layer and the floating plates embedded between the steel mesh.

[0025] A method for on-site casting, applied to the aforementioned anti-settlement foundation for communication towers suitable for permeable soil layers, is characterized by comprising the following steps:

[0026] Step 1: Excavation of the foundation pit. In the selected construction area, locate the soft soil layer and pre-mark the depth of the foundation pit to line L. Excavate to the line L of the soft soil layer, so that the foundation pit penetrates the surface hard soil and reaches the soft soil layer.

[0027] Step 2: Excavation of the clock base pit. Continue excavating the clock base pit downwards from the bottom of the foundation pit.

[0028] Step 3: Strong compaction treatment of the bell bottom pit. The bottom of the bell bottom pit is subjected to strong compaction treatment by a ton-class strong compaction machine to form a strong compaction expansion zone. The compaction continues until the depth of the single click of the ton-class strong compaction machine is no more than 2cm.

[0029] Step 4: Excavation of the outer water-blocking ring pit. The outer water-blocking ring pit is excavated coaxially with the foundation pit outside the foundation pit. The minimum distance between the outer water-blocking ring pit and the foundation pit is greater than 5m, and the top height of the outer water-blocking ring pit is 50cm lower than the ground height.

[0030] Step 5: Grouting channel construction. The grouting channel is opened between the outer water-blocking ring pit and the foundation pit, and the side steel reinforcement cage is inserted into the grouting channel.

[0031] Step Six: Place the main reinforcing cage and perform the first pour. Place the main reinforcing cage into the foundation pit and the bell bottom pit, and then perform the first concrete pour. Stop pouring when the grouting channel is reached to form the first grouting layer.

[0032] Step 7: Micro plate load test. After the first grouting layer has solidified, the settlement resistance of the foundation pit is tested by a micro plate load test. Subsequent pouring can only be carried out after the test is qualified.

[0033] Step 8: Second pouring. After passing the inspection, the second pouring is carried out. The concrete is poured to the top height inside the outer water-blocking ring pit to form the second grouting layer. During the second pouring, the concrete extends from the inside of the foundation pit to the outer water-blocking ring pit through the grouting channel, so that the concrete in the foundation pit and the concrete in the outer water-blocking ring pit are integrated.

[0034] Step 9: Construction of floating slab layer. A floating slab layer is poured on top of the second grouting layer. The floating slab layer consists of a steel mesh and floating slabs. The steel mesh is laid on the top surface of the second grouting layer, and the floating slabs are embedded between the steel mesh.

[0035] Step 10: Construction of composite concrete slab layer. A composite concrete slab layer is laid on top of the floating slab layer, and the bonding strength between the composite concrete slab layer and the floating slab layer is improved by anchoring nails.

[0036] Step 11: Construction of the communication tower foundation base. The communication tower foundation base is constructed on top of the composite concrete slab.

[0037] Furthermore, in step three, the impact force extends the depth of the bell-bottom pit downwards by 40cm-2m.

[0038] Compared with the prior art, the beneficial effects of the present invention are:

[0039] By using a cross-sectional structure that is narrower at the top and wider at the bottom, and then using high-intensity compaction to form a high-intensity compaction expansion zone, the bearing area at the bottom of the foundation is significantly increased compared to the cross-section of the foundation pit. At the same time, the density of the deep soil at the bottom of the pit is significantly improved. A water-blocking ring pit is set coaxially on the outside of the foundation pit. This ring-shaped water-blocking structure can effectively block external seepage water from penetrating towards the foundation pit, reduce the weakening of the foundation bearing capacity by groundwater erosion, and significantly expand the contact area between the foundation and the soil. This disperses the vertical pressure and horizontal wind load of the communication tower to a larger area of ​​stable undisturbed soil, and provides more reliable lateral support for the bonding between concrete and undisturbed soil. This effectively solves the problems of continuous softening of the foundation soil, decreased bearing capacity, weak horizontal wind resistance, lateral displacement, and concrete cracking caused by the concentration of vertical loads in conventional foundations in seepage soil layers.

[0040] By excavating a grouting channel between the foundation pit and the outer water-blocking ring pit, the foundation pit and the outer water-blocking ring pit are connected. A side steel reinforcement cage is set in the grouting channel to form an integral steel reinforcement skeleton, so that the concrete in the foundation pit and the concrete in the outer water-blocking ring pit are integrated into one, forming a closed ring-shaped reinforced concrete system, which significantly improves the integrity and crack resistance of the overall foundation structure.

[0041] Simultaneously, a two-stage grouting and layered pouring method is adopted. The first grouting layer is poured first, and after it solidifies, it passes the micro plate load test before the second grouting layer is poured. A quality inspection node is set in the middle to ensure that the first grouting layer reaches the design bearing capacity before construction can continue. This effectively avoids the problems of uneven quality and uncontrollable settlement that may occur with traditional one-time pouring.

[0042] A floating slab layer and a composite concrete slab layer are sequentially installed above the second grouting layer, and the bonding strength is enhanced by anchor nails to form a high-rigidity bearing platform at the top. The floating slab layer consists of a steel mesh and floating slabs. The steel mesh is laid on the top surface of the second grouting layer, and the floating slabs are embedded between the steel mesh, which effectively enhances the bending stiffness of the foundation and the durability of the superstructure, ensuring the stability of the communication tower foundation base under long-term loads and environmental effects. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall cross-sectional structure of the anti-settlement foundation of the present invention;

[0044] Figure 2 This is a schematic diagram of the foundation pit, the outer water-blocking ring pit, and the bell bottom pit of the present invention.

[0045] In the diagram: 1. Foundation pit; 2. Bell bottom pit; 3. Grouting channel; 4. Outer water-blocking ring pit; 5. Communication tower foundation base; 6. Composite concrete slab; 601. Anchor nail; 7. Floating slab layer; 8. First grouting layer; 9. Second grouting layer; 10. Side reinforcement cage; 11. Main reinforcement cage; 12. Support pile; 13. Dynamic compaction expansion zone. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] like Figures 1-2 As shown, the present invention provides a technical solution: a communication tower anti-settlement foundation suitable for permeable soil layers and its on-site casting method. The communication tower anti-settlement foundation suitable for permeable soil layers includes: a bell-bottom pit 2 and a foundation pit 1. The foundation pit 1 is excavated vertically downward from the ground until the depth of the foundation pit 1 reaches the soft soil layer line L, penetrating the surface hard soil to reach the soft soil layer. The bell-bottom pit 2 is excavated downward on the basis of the foundation pit 1 to a depth of not less than 2m, and the diameter of the bell-bottom pit 2 is larger than the diameter of the foundation pit 1, forming a cross-sectional structure that is narrow at the top and wide at the bottom, so that the bearing area at the bottom of the foundation is significantly increased compared with the cross-section of the foundation pit 1. On the basis of the bell-bottom pit 2, a strong compaction extension zone 13 is formed by strong compaction downward.

[0048] A water-blocking ring pit 4 is set on the outside of the foundation pit 1, coaxial with the foundation pit 1. The water-blocking ring pit 4 is excavated downward in a ring shape from the ground, surrounding the foundation pit 1. The minimum distance between the water-blocking ring pit 4 and the foundation pit 1 is greater than 5m, ensuring that the outer ring structure has sufficient radial dimensions to distribute the load. The top height inside the water-blocking ring pit 4 is 50cm lower than the ground height, which is a sunken design.

[0049] A grouting channel 3 is also excavated between the foundation pit 1 and the outer water-blocking ring pit 4, which allows for one-time grouting between the foundation pit 1 and the outer water-blocking ring pit 4.

[0050] To ensure the smooth implementation of the above embodiments, it is necessary to understand that the dynamic compaction extension zone is a dense soil layer area formed after being treated by a 25-ton dynamic compaction machine. The dynamic compaction will extend the depth of the Zhongdi pit 2 downward by 20cm-200cm, and the compaction will continue until the single-shot subsidence of the 25-ton dynamic compaction machine is no more than 2cm.

[0051] The outer water-blocking ring pit 4 can prevent external seepage water from penetrating towards the foundation pit 1. At the same time, it also serves as a load-bearing expansion. The large-spacing outer ring structure of more than 3 meters greatly expands the contact area between the foundation and the soil, distributing the vertical pressure and horizontal wind load of the communication tower to a larger area of ​​stable undisturbed soil. In order to make the concrete and undisturbed soil more effectively bonded, even if the anti-settlement effect in the foundation pit 1 is reduced due to seepage and other factors, the outer water-blocking ring pit 4 can still provide reliable lateral support, avoiding local settlement and concrete cracking caused by concentrated load.

[0052] The grouting channel 3 is equipped with a side steel reinforcement cage 10, which is arranged along the channel and connected to the main steel reinforcement cage 11 in the foundation pit 1 to form an integral steel reinforcement skeleton. The grouting channel 3 provides a flow path for concrete to extend from the inside of the foundation pit 1 to the outer water-blocking ring pit 4 during pouring, so that the concrete in the foundation pit 1 and the concrete in the outer water-blocking ring pit 4 are integrated. The side steel reinforcement cage 10 enhances the structural strength of the concrete in the channel.

[0053] To ensure the smooth implementation of the above embodiments, a main reinforcing cage 11 and supporting piles 12 are provided in the foundation pit 1. A first grouting layer 8 is provided in the foundation pit 1 and the bell bottom pit 2. The grouting height of the first grouting layer 8 extends from the strong compaction expansion zone 13 to the grouting channel 3, retaining the height above the grouting channel 3 to prevent the first grouting from spreading from the grouting channel 3 into the outer water-blocking ring pit 4. A second grouting layer 9 is provided above the first grouting layer 8. The second grouting layer 9 extends from the top of the first grouting layer 8 to the inner height of the outer water-blocking ring pit 4. The main reinforcing cage 11 and supporting piles 12 are wrapped in the first grouting layer 8 and the second grouting layer 9, providing internal steel reinforcement skeleton support for the grouting area.

[0054] A floating slab layer 7 is laid on top of the second grouting layer 9. The floating slab layer 7 extends from the second grouting layer 9 to the ground. A composite concrete slab layer 6 is laid on top of the floating slab layer 7. The composite concrete slab layer 6 and the floating slab layer 7 are further strengthened by anchor nails 601. The communication tower foundation base 5 is located on the composite concrete slab layer 6.

[0055] To ensure the smooth implementation of the above embodiments, this embodiment provides an on-site casting method for anti-settlement foundations of communication towers suitable for permeable soil layers, including the following steps:

[0056] Step 1: Excavation of foundation pit 1;

[0057] In the selected construction area, where water seepage is present, the soft soil layer is located and the foundation depth is pre-marked to line L. The excavation depth is then extended to line L of the soft soil layer, allowing the foundation pit 1 to penetrate the surface hard soil and reach the soft soil layer, providing working space for the subsequent construction of the bell bottom pit 2. During the excavation process, protective plates are installed simultaneously to maintain the stability of the wall surface.

[0058] Step 2: Excavation of Bell Pit 2. Continue excavating Bell Pit 2 downwards from the bottom of Pit 1.

[0059] Step 3: Strong compaction treatment of the bell bottom pit;

[0060] After the excavation of Zhongdi Pit 2 is completed, the bottom of Zhongdi Pit 2 is subjected to strong compaction treatment using a 25-ton class dynamic compaction machine. This process rearranges the soil particles and reduces the porosity. The strong compaction extends the depth of Zhongdi Pit 2 downward by 40cm-2m, forming a strong compaction expansion zone 13. During construction, the compaction continues until the depth of each 25-ton class dynamic compaction machine shot is no more than 2cm.

[0061] Step 4: Excavation of the outer water-blocking ring pit 4;

[0062] An outer water-blocking ring pit 4 was excavated outside the foundation pit 1.

[0063] Step 5: Construction of grouting channel 3;

[0064] A grouting channel 3 is constructed between the outer water-blocking ring pit 4 and the foundation pit 1 to connect the two. Side steel reinforcement cages 10 are inserted into the grouting channel 3, and the side steel reinforcement cages 10 are arranged along the direction of the channel.

[0065] Step Six: Place the main steel reinforcement cage 11 and perform the first pouring;

[0066] The main steel cage 11 is placed into the foundation pit 1 and the bell bottom pit 2, and then the first concrete pouring is carried out. The pouring is stopped at the grouting channel 3 to form the first grouting layer 8. The first pouring only goes up to the grouting channel 3 and then stops.

[0067] Step 7: Miniature plate load test;

[0068] After the first grouting layer 8 solidifies, the settlement resistance of the foundation pit 1 is tested by a micro plate load test. By applying graded loads to the solidified concrete surface and measuring the settlement, it is determined whether the first grouting layer 8 has reached the design bearing capacity. Subsequent pouring can only proceed after the test is passed.

[0069] Step 8: Second pouring;

[0070] After passing the inspection, the second pour is carried out, pouring to the top height inside the outer water-blocking ring pit 4 to form the second grouting layer 9. During the second pour, the concrete extends from the inside of the foundation pit 1 to the outer water-blocking ring pit 4 through the grouting channel 3, so that the concrete in the foundation pit 1 and the concrete in the outer water-blocking ring pit 4 are integrated.

[0071] Step 9: Construction of floating slab layer 7;

[0072] A floating plate layer 7 is poured above the second grouting layer 9. The floating plate layer 7 consists of a steel mesh and floating plates. The steel mesh is laid on the top surface of the second grouting layer 9, and the floating plates are embedded between the steel mesh. Anchor nails 601 are pre-installed during the pouring process.

[0073] Step 10: Construction of composite concrete slab layer 6;

[0074] Step 11: Construction of the communication tower foundation base 5. The communication tower foundation base 5 is constructed on top of the composite concrete slab layer 6.

[0075] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A settlement-resistant foundation for communication towers suitable for permeable soil layers, characterized in that, include: The foundation pit (1) is excavated vertically downward from the ground to the soft soil layer line L, penetrating the surface hard soil to reach the soft soil layer; The bell pit (2) is dug down to a depth of not less than 2m from the bottom of the foundation pit (1), and the diameter of the bell pit (2) is greater than the diameter of the foundation pit (1), forming a cross-sectional structure that is narrow at the top and wide at the bottom. The high-impact expansion zone (13) is located at the bottom of the bell pit (2) and is formed by high-impact impact downwards. The outer water-blocking ring pit (4) is coaxially arranged with the foundation pit (1) on the outside of the foundation pit (1), and is excavated downwards in a ring shape from the ground to surround the foundation pit (1). Grouting channel (3) is excavated between the foundation pit (1) and the outer water-blocking ring pit (4) to connect the foundation pit (1) and the outer water-blocking ring pit (4). The first grouting layer (8) is filled into the foundation pit (1) and the bell bottom pit (2). The second grouting layer (9) is set above the first grouting layer (8) and extends from the top of the first grouting layer (8) to the top height of the outer water-blocking ring pit (4); The floating slab layer (7) is laid on top of the second grouting layer (9) and extends to the ground; A composite concrete slab (6) is laid on top of the floating slab (7) and its bonding strength with the floating slab (7) is enhanced by anchors (601); The communication tower foundation base (5) is located above the composite concrete slab (6).

2. The anti-settlement foundation for communication towers suitable for permeable soil layers according to claim 1, characterized in that: The main steel cage (11) and the supporting piles (12) are set in the foundation pit (1). The grouting height extends from the strong compaction expansion zone (13) to the grouting channel (3), and the height above the grouting channel (3) is retained. The concrete extends from the inside of the foundation pit (1) to the outer water-blocking ring pit (4) through the grouting channel (3), so that the concrete in the foundation pit (1) and the concrete in the outer water-blocking ring pit (4) are connected as one.

3. The anti-settlement foundation for communication towers suitable for permeable soil layers according to claim 1, characterized in that: The minimum distance between the outer water-blocking ring pit (4) and the foundation pit (1) is greater than 5m, and the top height inside the outer water-blocking ring pit (4) is 50cm lower than the ground height.

4. The anti-settlement foundation for communication towers suitable for permeable soil layers according to claim 1, characterized in that: The strong compaction extension zone (13) is a dense soil layer area formed after being treated by a 25-ton strong compaction machine. The strong compaction extends the depth of the bell pit (2) downward by 20cm-200cm.

5. The anti-settlement foundation for communication towers suitable for permeable soil layers according to claim 2, characterized in that: The grouting channel (3) is provided with a side steel cage (10), which is arranged along the channel direction of the grouting channel (3) and connected with the main steel cage (11) to form an integral steel skeleton.

6. The anti-settlement foundation for communication towers suitable for permeable soil layers according to claim 2, characterized in that: The main steel cage (11) and the support pile (12) are enclosed within the first grouting layer (8) and the second grouting layer (9).

7. The anti-settlement foundation for communication towers suitable for permeable soil layers according to claim 1, characterized in that: The floating plate layer (7) consists of a steel mesh and floating plates. The steel mesh is laid on the top surface of the second grouting layer (9), and the floating plates are embedded between the steel mesh.

8. A method for on-site casting, applied to the anti-settlement foundation of a communication tower suitable for permeable soil layers as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Excavation of the foundation pit (1): In the selected construction area, locate the soft soil layer and pre-mark the depth of the foundation pit to line L. Excavate to the line L of the soft soil layer, so that the foundation pit (1) penetrates the surface hard soil and reaches the soft soil layer. Step 2: Excavation of the clock bottom pit (2) Continue to excavate the clock bottom pit (2) at the bottom of the foundation pit (1). Step 3: Strong compaction treatment of the bell pit (2). The bottom of the bell pit (2) is subjected to strong compaction treatment by a 25-ton strong compaction machine to form a strong compaction expansion zone (13). The compaction continues until the depth of the 25-ton strong compaction machine downward is no more than 2cm. Step 4: Excavation of the outer water-blocking ring pit (4) The outer water-blocking ring pit (4) is excavated coaxially with the foundation pit (1) on the outside of the foundation pit (1). The minimum distance between the outer water-blocking ring pit (4) and the foundation pit (1) is greater than 5m, and the top height inside the outer water-blocking ring pit (4) is 50cm lower than the ground height. Step 5: Construction of grouting channel (3) The grouting channel (3) is opened between the outer water-blocking ring pit (4) and the foundation pit (1), and the side steel cage (10) is inserted into the grouting channel (3). Step 6: Place the main steel cage (11) and perform the first pour. Place the main steel cage (11) into the foundation pit (1) and the bell bottom pit (2), and then perform the first concrete pour. Stop pouring when the grouting channel (3) is reached to form the first grouting layer (8). Step 7: Micro plate load test. After the first grouting layer (8) has solidified, the anti-settlement ability of the foundation pit (1) is tested by micro plate load test. Subsequent pouring can only be carried out after the test is qualified. Step 8: Second pouring. After passing the inspection, the second pouring is carried out. The concrete is poured to the top height inside the outer water-blocking ring pit (4) to form the second grouting layer (9). During the second pouring, the concrete extends from the inside of the foundation pit (1) to the outer water-blocking ring pit (4) through the grouting channel (3), so that the concrete in the foundation pit (1) and the concrete in the outer water-blocking ring pit (4) are connected as one. Step 9: Construction of floating plate layer (7) Floating plate layer (7) is poured above the second grouting layer (9). The floating plate layer (7) is composed of steel mesh and floating plates. The steel mesh is laid on the top surface of the second grouting layer (9) and the floating plates are embedded between the steel mesh. Step 10: Construction of composite concrete slab (6): A composite concrete slab (6) is laid on top of the floating slab (7), and the bonding strength between the composite concrete slab (6) and the floating slab (7) is improved by anchor nails (601). Step 11: Construction of the communication tower foundation base (5) The communication tower foundation base (5) is constructed on top of the composite concrete slab (6).

9. The on-site casting method according to claim 8, characterized in that, In step three, the strong compaction extends the depth of the bell bottom pit (2) downward by 40cm-2m.

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