Composite foundation pit supporting structure of full miscellaneous fill stratum

Abstract

The invention belongs to the technical field of foundation pit supporting, and particularly discloses a composite foundation pit supporting structure of a full miscellaneous fill stratum, the composite foundation pit supporting structure comprises a soil nail part and a wall body part, the soil nail part is used for being embedded in a soil body on the side wall of a foundation pit, and the wall body part is connected with the soil nail part. The wall part comprises a retaining wall and a buffer wall, the retaining wall is provided with at least one buffer platform, the side wall of the foundation pit is provided with a buffer groove corresponding to the buffer platform, the retaining wall is used for being laid on the side wall of the foundation pit, and the buffer platform is located in the buffer groove. The soil nail part comprises a first soil nail and a second soil nail, the first soil nail is embedded in a foundation pit side wall soil body, the embedding position of the first soil nail corresponds to the area, except the buffer platform, of the retaining wall, the second soil nail is provided with a traction cable, the second soil nail is embedded in the foundation pit side wall soil body, and the embedding position of the second soil nail corresponds to the position of the buffer platform; and the traction cable is connected with the buffer wall. According to the device, the situation that falling objects directly fall into the foundation pit to threaten the safety of buildings or personnel is effectively avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of foundation pit support, and particularly relates to a composite foundation pit support structure for all miscellaneous fill soil strata. Background Technique

[0002] With the acceleration of the urbanization process, the density of urban buildings is continuously increasing, and the demand for construction land is growing rapidly. Many cities have to carry out construction on sites covered with soft miscellaneous fill. When carrying out construction, it is often necessary to excavate a soil pit at the basic design position according to the base elevation and the basic plane size. This soil pit is the foundation pit. Support is the retaining, reinforcement and protection measures adopted for the side wall and the surrounding environment to ensure the safety of the surrounding environment of the foundation pit.

[0003] The miscellaneous fill layer contains a lot of organic matter, has low bearing capacity and poor self-stability. In the support of deep miscellaneous fill foundation pits, when slope excavation is not allowed due to space limitations, generally, schemes such as row piles plus prestressed anchor cables for support and jet grouting piles for strengthening the miscellaneous fill layer are adopted, but the support costs of these schemes are relatively high. In contrast, soil nail wall support is more suitable for use in miscellaneous fill layers because of its lower cost and better effect. Soil nail support, also called soil nail wall, is an in-situ soil reinforcement technology. Its structure is a composite body formed by firmly bonding the reinforcing members arranged in the slope body with the surrounding soil, and a support structure similar to a gravity retaining wall composed of the surface layer.

[0004] The traditional soil nail wall only uses the reinforcing members implanted inside the soil body in cooperation with the concrete or other protective materials on the soil surface to reinforce and protect the side wall of the foundation pit, and there is no effective secondary protection. Due to the characteristics of water immersion and collapsibility of the miscellaneous fill layer, there is still a risk of soil collapse under the erosion of rainwater after the soil nail wall support is reinforced. The soil nail wall bears the weight of the soil body. Once soil collapse occurs, the collapsed soil body will directly fall into the foundation pit along the side wall of the foundation pit, which will pose a great safety threat to the surrounding buildings or personnel.

[0005] As disclosed in the Chinese invention patent with the publication number CN114892676B, a foundation pit soil nailing wall support and its construction method are provided. It forms a soil nailing wall support for the side wall of the foundation pit through anchor-pulled steel bars in cooperation with the steel bar mesh and concrete wall of the soil nailing wall. This support structure only takes reinforcement measures for the side wall of the foundation pit. If soil collapse occurs on the side wall of the foundation pit, the collapsed soil will directly fall into the foundation pit along the soil nailing wall below the collapse, which seriously threatens the safety of the construction workers and existing buildings below the foundation pit. Moreover, if the collapse area is at a relatively high horizontal position, the collapsed soil will be affected by gravity during the process of falling along the soil nailing wall, and it will impact the buildings or personnel in the foundation pit with a relatively large impact force, causing relatively serious safety accidents. Another example is the Chinese invention patent with the publication number CN107119682B, which discloses a soil nailing wall and its construction method. It forms a soil nailing wall support for the side wall of the foundation pit through grouted soil nails in cooperation with the wall body. This support structure still has the drawback of only strengthening the side wall of the foundation pit without secondary protection. When soil collapse occurs, the collapsed soil will pose a safety threat to the construction workers and existing buildings below the foundation pit. Summary of the Invention

[0006] Aiming at the above problems, the purpose of the present invention is to provide a composite foundation pit support structure for alluvial fill soil strata, which can effectively buffer and block the falling objects during the collapse of the foundation pit, and effectively avoid the safety threat to buildings or personnel caused by the direct fall of the falling objects into the foundation pit.

[0007] The technical solution of the present invention is: a composite foundation pit support structure for alluvial fill soil strata, including a soil nailing part and a wall part. The soil nailing part is used to be embedded in the soil body of the side wall of the foundation pit, and the wall part is connected to the soil nailing part and is used to protect the side wall of the foundation pit.

[0008] The wall part includes a retaining wall and a buffer wall. The retaining wall is provided with at least one buffer platform, and the side wall of the foundation pit is provided with a buffer groove corresponding to the buffer platform. The retaining wall is used to be laid on the side wall of the foundation pit, and the buffer platform is located in the buffer groove. The buffer wall is arranged on the buffer platform and is used to buffer and block the falling objects after soil collapse; the soil nailing part includes a first soil nail and a second soil nail. The first soil nail is embedded in the soil body of the side wall of the foundation pit, and the embedding position of the first soil nail corresponds to the area of the retaining wall except the buffer platform. The exposed end of the first soil nail is fixed on the retaining wall. The second soil nail has a pulling cable, the second soil nail is embedded in the soil body of the side wall of the foundation pit, and the embedding position of the second soil nail corresponds to the position of the buffer platform. The exposed end of the second soil nail is fixed on the retaining wall, and the pulling cable is connected to the buffer wall.

[0009] In actual use, the soil nail part and the wall part are connected to each other to form an integral support structure. In the alluvial fill soil stratum, this synergistic effect can better cope with the complexity of the stratum. For example, the soil nail part can transfer the soil pressure received by the wall part to the deeper stable soil mass, while the wall part can provide lateral restraint for the soil nail part to prevent the soil nail from bending or breaking due to excessive lateral soil pressure.

[0010] A traditional soil nail wall structure is formed by using a retaining wall and the first soil nail. A buffer platform is provided on the retaining wall to cooperate with the buffer groove on the side wall of the foundation pit. When the soil mass deforms or moves, this structure can better adapt to the displacement change of the soil mass. And when the soil mass collapses, the buffer wall provided at the edge of the buffer platform can effectively block the falling objects of the collapse. For example, during the construction stage of a building after the foundation pit support is completed in the later stage, when the soil masses on both sides of the foundation pit are washed by rainwater and have deformation or slight movement, the buffer platform can have a certain movement space in the buffer groove. When there is a large movement resulting in the collapse of the soil mass, the buffer wall can prevent the falling objects from directly falling into the foundation pit and posing a safety threat to the building or personnel.

[0011] Among them, the first soil nail is embedded in the soil mass corresponding to the area of the retaining wall except the buffer platform and is fixed to the retaining wall. It mainly plays an anchoring role for the conventional part of the retaining wall and enhances the stability of the retaining wall under normal stress conditions. In the alluvial fill soil, due to the uneven soil quality, the first soil nail can provide stable supporting force for the retaining wall in different soil quality areas. The second soil nail is embedded in the soil mass corresponding to the buffer platform, and its pulling cable is connected to the buffer wall. This structural design enables the second soil nail to provide a pulling effect on the buffer wall through the pulling cable when the buffer wall is impacted by the falling objects of the soil mass collapse, preventing the buffer wall from collapsing or shifting due to excessive impact force. At the same time, the second soil nail also plays an additional anchoring role for the part of the retaining wall where the buffer platform is located, enhancing the stability of this part.

[0012] Furthermore, the second soil nail includes a rod body and a buffer part. A grouting channel and a pulling channel are arranged along the length direction of the rod body. The buffer part is arranged inside the rod body. One end of the pulling cable passes through the pulling channel and is connected to the buffer part, and the other end is fixed to the buffer wall. When the buffer wall is impacted by the falling objects, the buffer part is pulled through the pulling cable, and the buffer part is used to buffer and reduce the impact force. In the alluvial fill soil stratum, the structure of the soil mass is loose and uneven. Through the grouting channel, a suitable slurry can be injected, and the slurry fills the gap between the second soil nail and the soil mass, making the second soil nail closely combined with the surrounding soil mass. The enhancement of this bonding force helps to improve the reinforcement effect of the second soil nail on the soil mass and prevent the soil mass from collapsing or deforming excessively. And the pulling channel provides an independent threading space for the pulling cable, so that it can be ensured that the pulling cable will not be interfered by other factors during the force transmission process, ensuring the accuracy and effectiveness of the force transmission.

[0013] Furthermore, the rod body is divided into a buffer section, a grouting section, and an installation section. Grouting holes are provided on the side wall of the grouting section, and the grouting holes communicate with the grouting channel. Installation parts are provided on the installation section, and the installation parts are used to closely adhere to the side wall of the foundation pit. In the alluvial fill soil stratum, when the buffer wall is impacted by falling objects and the force is transmitted through the pulling cable, the buffer section can play a buffering role, avoiding the impact force directly acting on other parts of the soil nail structure, reducing the damage to the grouting section and the installation section, thus protecting the integrity of the soil nail structure and ensuring the stability and effectiveness of the soil nail during the support process.

[0014] Further, a buffer platform is provided every 1 m to 3 m in the horizontal height of the retaining wall. The buffer platform is horizontally arranged on the retaining wall in the horizontal direction, and each buffer platform corresponds to a buffer wall.

[0015] In practice, by adopting interval-stage protection measures, the buffer wall on the buffer platform can buffer and block the soil body on the side wall of the foundation pit above its horizontal height, effectively avoiding local damage of the buffer wall caused by excessive stress concentration at a certain height. Moreover, in the alluvial fill soil stratum, the soil pressure is unevenly distributed at different heights. By arranging a buffer platform every 1 m to 3 m in the horizontal height of the retaining wall, the overall soil pressure can be dispersed.

[0016] In addition, there may be differences in the soil properties of the alluvial fill soil stratum in the vertical direction. Arranging the buffer platforms at intervals enables the retaining wall to better adapt to such changes. Within the interval range of 1 m to 3 m, the soil at different heights may have different properties such as density and water content. The buffer platform can adjust its interaction with the surrounding structures according to the soil properties at its height. For example, at a height where the soil density is relatively low, the buffer platform can have more adjustment space in the buffer groove to adapt to the possible large deformation of the soil.

[0017] In addition, the horizontally arranged buffer platforms are distributed on the retaining wall in the horizontal direction, which helps to improve the overall stability of the retaining wall in the horizontal direction. When there is lateral pressure on the soil body, multiple buffer platforms and their related buffer walls, soil nail parts and other structures form a stable system similar to a framework. This structural system can effectively resist the lateral soil pressure and reduce the possibility of the retaining wall undergoing lateral deformation or tilting.

[0018] Most importantly, this setting method increases the flexibility of the retaining wall structure. When affected by external factors such as changes in the groundwater level, construction vibrations in the vicinity, rainwater scouring, etc., buffer platforms at different heights can adjust their own states independently or cooperatively. For example, when the water level rises, resulting in an increase in the soil pressure at the lower part, the lower buffer platform can, to a certain extent, adjust the stress state of the retaining wall through the synergistic effect of the buffer wall and the second soil nail, while the upper buffer platform can also maintain its own stable state without affecting the structural function of the entire retaining wall.

[0019] Furthermore, the buffer wall includes multiple groups of buffer components, and each group of buffer components includes a buffer base and a baffle. The buffer base is arranged on the buffer platform. The baffle is installed on the buffer base, and the baffle is used to block the falling objects after the soil collapse; the end of the pulling cable is connected to the baffle. The buffer wall is composed of multiple groups of buffer components, and this modular design makes the buffer wall more flexible in installation and adjustment. In the foundation pit support of alluvial fill soil layers, the soil conditions in different areas may vary, and multiple groups of buffer components can be combined and arranged according to actual needs. For example, if the risk of soil collapse in a certain area is relatively high, the actual material of the baffle can be replaced to make the baffle have better impact resistance. Also, in later maintenance or local repair, the modular buffer components are more convenient to operate. If a certain group of buffer components is damaged, it can be replaced or repaired individually without affecting the function of the entire buffer wall.

[0020] Even further, each baffle corresponds to at least two buffer bases. Multiple buffer bases can provide more uniform support for the baffle, thereby enhancing the stability of the overall structure. When facing soil collapse or other external force impacts, this design can better disperse the pressure, reduce the situation of excessive local stress, and reduce the risk of structural damage. Also, two buffer bases can provide a more effective buffering effect. When the soil moves or deforms, the buffer base can absorb and disperse energy, reducing the direct impact on the baffle, thereby extending the service life of the baffle.

[0021] Furthermore, an installation base is provided at the outer edge of the buffer platform. The buffer base includes a base plate, a limiting plate, and a first elastic member. The base plate is hinged to the installation base; the limiting plate is fixed to the installation base, and the fixing position is adjacent to the hinged position of the base plate; the first elastic member is disposed between the base plate and the limiting plate, and both ends of the first elastic member are respectively fixed to the base plate and the limiting plate. The base plate is hinged to the installation base, enabling the buffer base to rotate within a certain range. When the soil mass collapses, the falling object is blocked by the baffle, and the baffle transmits the impact force to the base plate. Subsequently, the base plate rotates, compressing the first elastic member to reduce the impact force. Moreover, the limiting function of the limiting plate can prevent the base plate from undergoing excessive flipping or displacement due to excessive impact force during impact, ensuring the integrity of the overall structure of the buffer base, thereby enabling the entire support structure to continuously and effectively function.

[0022] Furthermore, the included angle between the base plate and the limiting plate is 20° - 45°.

[0023] The working method of the present invention: A traditional soil nailing wall structure is formed by using a retaining wall and the first soil nail to protect the side wall of the foundation pit. When the soil mass deforms or moves, the buffer groove is used to adapt to the small displacement change of the soil mass. When the soil mass collapses, the buffer wall provided at the edge of the buffer platform can effectively block the falling objects during the collapse.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention utilizes the mutual connection of the soil nail part and the wall part to form an integral support structure, which can effectively protect the side wall of the foundation pit in the alluvial fill soil layer. Due to the complexity of the alluvial fill soil layer, the buffer wall provided on the buffer platform can effectively buffer and block the falling objects during the collapse of the foundation pit, effectively avoiding the direct fall of the falling objects into the foundation pit and posing a safety threat to buildings or personnel. Moreover, the buffer groove corresponding to the buffer platform can adapt to the small displacement change of the soil mass, effectively avoiding the displacement or collapse of a large area of the supporting wall part caused by the displacement change of the soil mass. Description of the Drawings

[0025] Figure 1 is the structural schematic diagram of the present invention;

[0026] Figure 2 is the partial cross-sectional view of the present invention;

[0027] Figure 3 is for Figure 2 the enlarged structural view of part A in

[0028] Figure 4 is the cross-sectional view of the second soil nail in Embodiment 1 of the present invention;

[0029] Figure 5It is a partial structural sectional view of the second soil nail in Embodiment 1 of the present invention;

[0030] Figure 6 It is a partial structural sectional view of the second soil nail in Embodiment 2 of the present invention.

[0031] Among them, 1 - retaining wall, 10 - buffer platform, 100 - installation base, 2 - buffer wall, 20 - buffer assembly, 21 - buffer base, 211 - base plate, 212 - limiting plate, 213 - first elastic member, 22 - baffle, 3 - first soil nail, 4 - second soil nail, 40 - pulling cable, 401 - buffer section, 402 - grouting section, 403 - installation section, 41 - rod body, 411 - grouting channel, 412 - pulling channel, 42 - buffer part, 421 - rotating shaft rod, 4211 - rotating groove, 4212 - transmission gear, 422 - sleeve member, 4221 - sliding rod, 4222 - sleeve, 4223 - limiting block, 423 - claw rod, 424 - second elastic member. Detailed implementation manners

[0032] The following combines the attached Figure 1 to the attached Figure 6 drawings to describe in detail the specific implementation manners of the present invention. In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 to the present invention.

[0033] The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features; in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0034] Embodiment 1

[0035] As Figure 1 shown, a composite foundation pit support structure for alluvial fill soil layers includes a soil nail part and a wall part. The soil nail part is used to be embedded in the soil body on the side wall of the foundation pit, and the wall part is connected to the soil nail part. The wall part is used to protect the side wall of the foundation pit.

[0036] The wall body part includes a retaining wall 1 and a buffer wall 2. The retaining wall 1 is provided with at least one buffer platform 10, and a buffer groove corresponding to the buffer platform 10 is provided on the side wall of the foundation pit. The retaining wall 1 is used to be laid on the side wall of the foundation pit, and the buffer platform 10 is located in the buffer groove. The buffer wall 2 is arranged on the buffer platform 10 and is used to buffer and block the falling objects after the soil mass collapses;

[0037] The soil nail part includes a first soil nail 3 and a second soil nail 4. Among them, as Figure 1 , Figure 2 shown, the numbers of both the first soil nail 3 and the second soil nail 4 are multiple, and the specific number is determined according to the actual supported alluvial fill stratum combined with the area of the foundation pit. In this embodiment, multiple first soil nails 3 are evenly distributed at intervals in a matrix, and multiple second soil nails 4 are distributed at intervals in a straight line, and the distance between two adjacent first soil nails 3 does not exceed 2m, and the distance between two adjacent second soil nails 4 does not exceed 3m.

[0038] The first soil nail 3 is embedded in the soil body on the side wall of the foundation pit. The embedding position of the first soil nail 3 corresponds to the area of the retaining wall 1 except the buffer platform 10, and the exposed end of the first soil nail 3 is fixed on the retaining wall 1. The second soil nail 4 has a pulling cable 40. The second soil nail 4 is embedded in the soil body on the side wall of the foundation pit. The embedding position of the second soil nail 4 corresponds to the position of the buffer platform 10, and the exposed end of the second soil nail 4 is fixed on the retaining wall 1, and the pulling cable 40 is connected to the buffer wall 2.

[0039] In actual use, the soil nail part and the wall body part are connected to each other to form an integral support structure. In the alluvial fill stratum, this synergistic effect can better cope with the complexity of the stratum. For example, the soil nail part can transfer the soil pressure received by the wall body part to the deeper stable soil body, and the wall body part can provide lateral restraint for the soil nail part to prevent the soil nail from bending or being damaged due to excessive lateral soil pressure.

[0040] The retaining wall 1 and the first soil nail 3 are used to form a traditional soil nail wall structure. The buffer platform 10 on the retaining wall 1 is matched with the buffer groove on the side wall of the foundation pit. When the soil mass deforms or moves, this structure with the buffer groove on the side wall of the foundation pit can better adapt to the displacement change of the soil mass. And when the soil mass collapses, the buffer wall 2 arranged at the edge of the buffer platform 10 can effectively block the falling objects of the collapse. For example, in the later construction stage of the building after the foundation pit support is completed, when the soil masses on both sides of the foundation pit are washed by rainwater and have deformation or slight movement, the buffer platform 10 can have a certain movement space in the buffer groove. When there is a large movement resulting in the collapse of the soil mass, the buffer wall 2 can prevent the falling objects from directly falling into the foundation pit and posing a safety threat to the building or personnel.

[0041] Among them, the first soil nail 3 is embedded in the soil corresponding to the area of the retaining wall 1 except the buffer platform 10 and is fixed to the retaining wall 1. It mainly plays an anchoring role in the conventional part of the retaining wall 1, enhancing the stability of the retaining wall 1 under normal stress conditions. In the miscellaneous fill soil, due to the uneven soil quality, the first soil nail 3 can provide stable support for the retaining wall 1 in different soil areas. The second soil nail 4 is embedded in the soil corresponding to the buffer platform 10, and its tension cable 40 is connected to the buffer wall 2. This structural design enables the second soil nail 4 to provide a pulling effect on the buffer wall 2 through the tension cable 40 when the buffer wall 2 is impacted by the soil collapse and falling objects, preventing the buffer wall 2 from collapsing or shifting due to excessive impact force. At the same time, the second soil nail 4 also plays an additional anchoring role in the part of the retaining wall 1 where the buffer platform 10 is located, enhancing the stability of this part.

[0042] It should be noted that: in this embodiment, the retaining wall 1 is formed by laying a steel mesh on the surface of the foundation pit side wall and then spraying a layer of concrete surface layer. The first soil nail 3 is a soil nail made of steel bars, and the tension cable 40 is made of steel cables.

[0043] Preferably, a buffer platform 10 is provided every 1 m to 3 m of the horizontal height along the retaining wall 1. The buffer platform 10 is horizontally arranged transversely on the retaining wall 1, and each buffer platform 10 corresponds to a buffer wall 2.

[0044] In practice, by adopting intermittent phased protection measures, the buffer wall 2 on the buffer platform 10 can be used to buffer and block the soil body of the foundation pit side wall above its horizontal height, effectively avoiding local damage of the buffer wall 2 caused by excessive stress concentration at a certain height. Moreover, in the fully miscellaneous fill soil layer, the soil pressure is unevenly distributed at different heights. By arranging a buffer platform 10 every 1 m to 3 m along the horizontal height of the retaining wall 1, the overall soil pressure can be dispersed.

[0045] Furthermore, there may be differences in the soil characteristics of the miscellaneous fill soil layer in the vertical direction. The intermittent arrangement of the buffer platforms 10 enables the retaining wall to better adapt to this change. Within the interval range of 1 m to 3 m, the soil bodies at different heights may have different characteristics such as density and water content. The buffer platform 10 can adjust its interaction with the surrounding structures according to the soil characteristics at its height. For example, at a height where the soil density is relatively low, the buffer platform 10 can have more adjustment space in the buffer groove to adapt to the possible large deformation of the soil body.

[0046] In addition, the horizontally arranged buffer platforms 10 are distributed along the horizontal direction on the retaining wall, which helps to improve the overall stability of the retaining wall in the horizontal direction. When there is lateral pressure on the soil mass, multiple buffer platforms 10 and their related buffer walls 2, soil nail parts and other structures form a stable system similar to a framework. This structural system can effectively resist lateral earth pressure and reduce the possibility of the retaining wall undergoing lateral deformation or inclination.

[0047] Most importantly, this setting method increases the flexibility of the retaining wall structure. When affected by external factors, such as changes in the groundwater level, construction vibration in the vicinity, rainwater scouring, etc., the buffer platforms 10 at different heights can adjust their own states independently or cooperatively. For example, when the water level rises, resulting in an increase in the pressure of the lower soil mass, the lower buffer platform 10 can, to a certain extent, adjust the stress state of the retaining wall 1 through the cooperative action of the buffer wall 2 and the second soil nail 4, while the upper buffer platform 10 can also maintain its own stable state and will not affect the structural function of the entire retaining wall.

[0048] Preferably, as Figure 1 , Figure 2 , Figure 3 shown, the buffer wall 2 includes multiple groups of buffer components 20, and each group of buffer components 20 includes a buffer base 21 and a baffle 22. The buffer base 21 is arranged on the buffer platform 10. The baffle 22 is installed on the buffer base 21, and the baffle 22 is used to block the falling objects after the soil mass collapses; the end of the pulling cable 40 is connected to the baffle 22.

[0049] The buffer wall 2 is composed of multiple groups of buffer components 20. This modular design makes the buffer wall 2 more flexible in installation and adjustment. In the foundation pit support of fully miscellaneous fill soil layers, the soil conditions in different areas may vary. Multiple groups of buffer components 20 can be combined and arranged according to actual needs. For example, if the risk of soil mass collapse is higher in a certain area, the actual material of the baffle 22 can be replaced to make the baffle 22 have better impact resistance. Moreover, in later maintenance or local repair, the modular buffer components 20 are also more convenient to operate. If a certain group of buffer components 20 is damaged, it can be replaced or repaired separately without affecting the function of the entire buffer wall 2.

[0050] The buffer base 21 is arranged on the buffer platform 10 and can provide stable support for the baffle 22. At the same time, the buffer base 21 itself may have certain buffer performance, such as the elastic parts in the previous structure, etc., and can absorb the impact force of the falling objects to a certain extent. The baffle 22 is directly used to block the falling objects after the soil mass collapses. The two work together, which can not only effectively block the falling objects, but also reduce the impact force on the entire support structure through the buffering effect of the buffer base 21.

[0051] In the fully miscellaneous filled soil stratum, the size, speed, and direction of the falling objects during soil collapse may have relatively large uncertainties. The combination of the buffer base 21 and the baffle 22 can adapt to this uncertainty and adjust the buffering and blocking effects according to the actual impact force situation.

[0052] Preferably, each baffle 22 corresponds to at least two buffer bases 21. In this embodiment, each baffle 22 corresponds to two buffer bases 21. As Figure 1 shown, the two buffer bases 21 are distributed at both ends of the baffle 22.

[0053] Multiple buffer bases 21 can provide more uniform support for the baffle 22, thereby enhancing the stability of the overall structure. When facing soil collapse or other external force impacts, this design can better disperse the pressure, reduce the situation of excessive local stress, and reduce the risk of structural damage. Moreover, the two buffer bases 21 can provide a more effective buffering effect. When the soil moves or deforms, the buffer base 21 can absorb and disperse energy, reduce the direct impact on the baffle 22, and thus extend the service life of the baffle 22.

[0054] It should be noted that: the number of buffer bases 21 is actually selected according to the length of the baffle 22, and the distance between the buffer bases 21 should not exceed 3m. And the length of each baffle 22 is selectively adapted according to its own material. Among them, the baffle 22 can be made of wood, metal, precast concrete slab and other materials. In this embodiment, a wooden board is used with a length of 2m.

[0055] Preferably, as Figure 3 shown, an installation base 100 is provided at the outer edge of the buffer platform 10. The buffer base 21 includes a base plate 211, a limiting plate 212, and a first elastic member 213. The base plate 211 is hinged to the installation base 100; the limiting plate 212 is fixed on the installation base 100, and the fixing position is adjacent to the hinged position of the base plate 211; the first elastic member 213 is arranged between the base plate 211 and the limiting plate 212, and both ends of the first elastic member 213 are fixed to the base plate 211 and the limiting plate 212 respectively.

[0056] The base plate 211 is hinged to the installation base 100, enabling the buffer base 21 to rotate within a certain range. When the soil collapses, the falling objects are blocked by the baffle 22, and the baffle 22 transmits the impact force to the base plate 211. Then, the base plate 211 rotates, and the impact force is reduced by compressing the first elastic member 213. Moreover, the limiting effect of the limiting plate 212 can also prevent the base plate 211 from over-turning or displacing due to excessive impact force during impact, ensuring the integrity of the overall structure of the buffer base 21, so that the entire support structure can continuously and effectively play its role.

[0057] In actual implementation of this embodiment, the mounting base 100 is a concrete pedestal cast together with the buffer platform 10. Before casting the concrete pedestal, a hinge shaft is pre-embedded and an installation groove is reserved. A rotating hole corresponding to the hinge shaft is provided on the substrate 211. The substrate 211 is sleeved on the rotating hole, and the limiting plate 212 is installed in the installation groove and fixed by bolts. The two ends of the first elastic member 213 are respectively fixed on the substrate 211 and the limiting plate 212. The first elastic member 213 is a commercially available damper.

[0058] Preferably, the included angle between the substrate 211 and the limiting plate 212 is 20°-45°. Within this angle range, the included angle between the substrate 211 and the limiting plate 212 can provide better structural stability. When the buffer pedestal 21 is impacted by the soil collapse debris or the pressure generated by soil deformation, the appropriate included angle can ensure a more stable connection between the substrate 211 and the limiting plate 212, preventing excessive deformation or damage of the structure. The included angle of 20°-45° helps the first elastic member 213 to exert the best energy absorption and buffering effect within this range. When an external force acts on the buffer pedestal 21, the first elastic member 213 can effectively elastically deform within this angle range, thereby absorbing and dispersing energy and reducing the impact on the entire support structure. In the alluvial fill soil layer, the deformation of the soil is complex and diverse. The included angle design of 20°-45° enables the buffer pedestal 21 to better adapt to the deformation of the soil. Whether it is soil settlement, lateral movement or other forms of deformation, the buffer pedestal 21 can maintain an effective block and buffer of the soil collapse debris by adjusting its own angle and elastic deformation. This angle range also has certain convenience during the construction process. Construction workers can relatively easily install the substrate 211 and the limiting plate 212 to the designated positions and adjust them to the appropriate included angle. At the same time, if fine adjustment of the included angle is required during use, the range of 20°-45° also provides a certain adjustment space, facilitating the maintenance and optimization of the performance of the buffer pedestal 21. In this embodiment, the included angle between the substrate 211 and the limiting plate 212 is 30°.

[0059] Preferably, as Figure 4 shown, the second soil nail 4 includes a rod body 41 and a buffer portion 42. The rod body 41 is provided with a grouting channel 411 and a pulling channel 412 along the rod length direction. The buffer portion 42 is arranged inside the rod body 41. One end of the pulling cable 40 passes through the pulling channel 412 and is connected to the buffer portion 42, and the other end is fixed on the buffer wall 2. When the buffer wall 2 is impacted by the falling object, the buffer member 42 is pulled through the pulling cable 40, and the buffer portion 42 is used for buffering and reducing the impact force.

[0060] In the fully miscellaneous filled soil stratum, the structure of the soil mass is loose and uneven. Through the grouting channel 411, a suitable grout can be injected. The grout fills the gap between the second soil nail 4 and the soil mass, enabling the second soil nail 4 to be tightly combined with the surrounding soil mass. The enhancement of this bonding force helps to improve the reinforcement effect of the second soil nail 4 on the soil mass and prevent the soil mass from collapsing or undergoing excessive deformation. The pulling channel 412 provides an independent threading space for the pulling cable 40, ensuring that the pulling cable 40 will not be interfered by other factors during the force transmission process, guaranteeing the accuracy and effectiveness of the force transmission. One end of the pulling cable 40 is connected to the buffer wall 2, and the other end is tightly connected to the second soil nail 4 through the connection with the buffer part 42. This connection method enables the buffer wall 2 and the soil nail structure to work together when dealing with the impact force of falling objects. When the buffer wall 2 is subjected to an impact force, not only do its own buffer components play a role, but also part of the impact force can be transmitted to the soil nail structure through the pulling cable 40 and the buffer part 42 for sharing, effectively improving the overall impact resistance performance of the entire support structure.

[0061] Preferably, as Figure 4 , Figure 5 shown, the rod body 41 is divided into a buffer section 401, a grouting section 402, and an installation section 403. Grouting holes are provided on the side wall of the grouting section 402, and the grouting holes are communicated with the grouting channel 411. Installation parts 43 are provided on the installation section 403, and the installation parts 43 are used to closely adhere to the side wall of the foundation pit. In the fully miscellaneous filled soil stratum, when the buffer wall 2 is impacted by falling objects and transmits force through the pulling cable 40, the buffer section 401 can play a buffering role, avoiding the impact force directly acting on other parts of the soil nail structure, reducing the damage to the grouting section 402 and the installation section 403, thereby protecting the integrity of the soil nail structure and ensuring the stability and effectiveness of the soil nail during the support process.

[0062] Preferably, as Figure 4 , Figure 5As shown in the figure, the buffer part 42 includes a rotating shaft rod 421, a sleeve part 422 and a claw rod 423. The rotating shaft rod 421 is rotatably arranged inside the rod body 41. A spiral groove 4211 is arranged on the side wall of one end of the rotating shaft rod 421, and a transmission gear 4212 is arranged at the end of the other end of the rotating shaft rod 421. The transmission gear 4212 rotates coaxially with the rotating shaft rod 421. The sleeve part 422 includes a sliding rod 4221 and a sleeve 4222. The sliding rod 4221 is slidably arranged inside the rod body 41 and can slide along the length direction of the rod body 41. The pulling cable 40 is connected to one end of the sliding rod 4221. One end of the sleeve 4222 is arranged at the other end of the sliding rod 4221, and the other end of the sleeve 4222 is sleeved on the end of the rotating shaft rod 421 provided with the spiral groove 4211. A limiting block 4223 corresponding to the spiral groove 4211 is arranged on the sleeve 4222, and the limiting block 4223 is slidably arranged in the spiral groove 4211. When the pulling cable 40 pulls the sliding rod 4221 to move towards the direction close to the sleeve 4222, the limiting block 4223 slides in the spiral groove 4211, prompting the rotating shaft rod 421 to rotate. The claw rod 423 is arranged through the rod body 41. A rack is arranged on one side of the claw part 423 located inside the rod body 41. The rack meshes with the transmission gear 4212. When the rotating shaft rod 421 rotates, the transmission gear 4212 drives the rack to move, and the claw rod 423 moves along with the rack and inserts into the soil body.

[0063] The cooperation between the spiral groove 4211 and the limiting block 4223 is the key to realizing buffering and energy conversion. This structural design enables the linear motion of the pulling cable 40 to be accurately converted into the rotational motion of the rotating shaft rod 421. Moreover, the existence of the spiral groove 4211 can also limit the movement range of the limiting block 4223 to a certain extent, preventing the sleeve 4222 from separating from the rotating shaft rod 421 and ensuring the integrity of the structure of the buffer part 42. The transmission gear 4212 is arranged at the end of the rotating shaft rod 421, providing a power source for the movement of the claw rod 423. When the rotating shaft rod 421 rotates, the transmission gear 4212 can effectively transmit the rotational power to the claw rod 423, and the claw rod 423 can insert into the soil body in a predetermined manner to enhance the connection between the soil nail and the soil body.

[0064] Embodiment 2

[0065] Different from Embodiment 1: Preferably, as Figure 6As shown, the buffer portion 42 further includes a second elastic member 424. One end of the second elastic member 424 is connected to the sleeve member 422, and the other end is clamped inside the rod body 41, which is used to apply resistance to the movement of the sleeve member 422 in the direction approaching the rotating shaft rod 421. This resistance can further buffer the impact force and prevent the impact force from acting completely on the rotating shaft rod 421 and subsequent structural components instantaneously. For example, when a relatively large falling object impacts the buffer wall 2, the second elastic member 424 can absorb a part of the energy, making the buffering process of the entire buffer portion 42 smoother. The second elastic member 424 uses a commercially available spring, which can automatically adjust the resistance to the sleeve member 422 according to the magnitude of the impact force. For a relatively small impact force, it allows the sleeve member 422 to move to a certain extent, enabling the force to be normally transmitted to the subsequent structure for buffering and processing; while for a relatively large impact force, it will apply a greater resistance to prevent the excessive transmission of the force from causing damage to the structural components. This helps the buffer portion 42 to adapt to the impact forces of falling objects of different sizes in the fully miscellaneous filled soil layer.

[0066] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A composite foundation pit support structure for all-mixed fill strata, comprising a soil nail part and a wall part, wherein the soil nail part is used to be embedded in the soil of the side wall of the foundation pit, the wall part is connected to the soil nail part, and the wall part is used to protect the side wall of the foundation pit; characterized in that: The wall portion comprises: The retaining wall (1) is provided with at least one buffer platform (10), the side wall of the foundation pit is provided with a buffer groove corresponding to the buffer platform (10), the retaining wall (1) is used for laying on the side wall of the foundation pit, and the buffer platform (10) is located in the buffer groove; A buffer wall (2) is arranged on the buffer platform (10) and is used to buffer and block falling objects after soil collapse; The soil nailing part comprises: a first soil nail (3) embedded in the soil of the side wall of the foundation pit, the embedding position of the first soil nail (3) corresponds to the area of ​​the retaining wall (1) other than the buffer platform (10), and the exposed end of the first soil nail (3) is fixed on the retaining wall (1); a second soil nail (4) having a pulling rope (40), the second soil nail (4) embedded in the soil of the side wall of the foundation pit, the embedding position of the second soil nail (4) corresponds to the position of the buffer platform (10), the exposed end of the second soil nail (4) is fixed on the retaining wall (1), and the pulling rope (40) is connected to the buffer wall (2).

2. A composite foundation pit support structure for all-mixed fill strata as claimed in claim 1, characterized in that: The second soil nail (4) comprises: a rod body (41) provided with a grouting channel (411) and a pulling channel (412) along the length direction of the rod; and a buffer part (42) provided inside the rod body (41); one end of a pulling rope (40) passes through the pulling channel (412) and is connected to the buffer part (42), and the other end is fixed to the buffer wall (2); when the buffer wall (2) is subjected to the impact force of a falling object, the buffer part (42) is pulled by the pulling rope (40), and the buffer part (42) is used to buffer and reduce the impact force.

3. A composite foundation pit support structure for all-mixed fill strata as claimed in claim 2, characterized in that: The rod body (41) is divided into a buffer section (401), a grouting section (402), and a mounting section (403). A grouting hole is provided on the side wall of the grouting section (402), and the grouting hole is connected to the grouting channel (411). A mounting member (43) is provided on the mounting section (403), and the mounting member (43) is used to be closely attached to the side wall of the foundation pit.

4. A composite foundation pit support structure for all-mixed fill strata as claimed in claim 1, characterized in that: The retaining wall (1) is provided with a buffer platform (10) at intervals of 1m to 3m along the horizontal height. The buffer platform (10) is transversely arranged on the retaining wall (1) along the horizontal direction. Each buffer platform (10) corresponds to a buffer wall (2).

5. The composite foundation pit support structure of all-mixed fill strata according to claim 1, characterized in that: The buffer wall (2) comprises a plurality of groups of buffer components (20), and each group of buffer components (20) comprises: A buffer base (21) is arranged on the buffer platform (10); A baffle (22) is installed on the buffer base (21), and the baffle (22) is used to block falling objects after soil collapse; the end of the pulling rope (40) is connected to the baffle (22).

6. A composite foundation pit support structure for all-mixed fill strata as claimed in claim 5, characterized in that: Each baffle (22) corresponds to at least two buffer bases (21).

7. A composite foundation pit support structure for all-mixed fill strata as claimed in claim 5, characterized in that: A mounting base (100) is provided at the outer edge of the buffer platform (10), and the buffer base (21) comprises: A base plate (211) is hinged on the mounting base (100); A limiting plate (212) is fixed on the mounting base (100), with the fixing position close to the hinge of the base plate (211); The first elastic member (213) is arranged between the base plate (211) and the limiting plate (212), and two ends of the first elastic member (213) are respectively fixed to the base plate (211) and the limiting plate (212).

8. A composite foundation pit support structure for all-mixed fill strata as claimed in claim 7, characterized in that: The included angle between the base plate (211) and the limiting plate (212) is 20° to 45°.

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