A separate pile foundation underpinning structure for a bridge with widened main line

Abstract

This utility model discloses a separate pile foundation underpinning structure for a bridge with widened main line, belonging to the field of bridge construction engineering technology. It includes a main longitudinal beam underpinning, a support mechanism, and an underpinning mechanism. Two main longitudinal beams are provided, with a gap between adjacent beams. The underpinning mechanism is located within the gap. Two sets of support mechanisms are located at the two ends of the main longitudinal beams. It also includes piers and a bridge body, with the bridge body positioned above the main longitudinal beams. By separating the main longitudinal beams from the original bridge piers, the structure maintains a simply supported stress state, effectively avoiding the risk of statically indeterminate stress. The stress system is clear and lightweight, preventing dynamic load changes during pier segment construction and ensuring controllable stress safety. Furthermore, it eliminates the need for rebar connections, avoiding damage to the original piers and simplifying complex procedures such as rebar positioning and interface treatment.

Description

Technical Field

[0001] This utility model relates to the field of bridge construction engineering technology, specifically a separate pile foundation support structure for a bridge with a widened main line. Background Technology

[0002] With the acceleration of urbanization, the demand for underground engineering projects such as urban rail transit and integrated utility tunnels has surged. As an important part of the urban transportation network, the space beneath existing elevated bridges often becomes the inevitable route for new tunnels. Traditional methods such as pile foundation removal or bridge demolition are not only costly but also pose problems such as traffic disruption and environmental impact. Therefore, pile foundation replacement technology has become the core means to solve the spatial game between "bridge and tunnel". The node connection between the pile foundation replacement structure and the original structure is the "choke point" to ensure the smooth transfer of load and the overall safety of the structure. Due to factors such as the collaborative work of the old and new structures, dynamic load transfer, and complex construction environment, there are many technical challenges in node connection.

[0003] Existing bridge pile foundation replacement methods include: 1. Setting active compensation, connecting the replacement beam and the pier; 2. Not setting active compensation, connecting the replacement beam and the pier, passive replacement, which cannot adjust the bridge attitude. The problems with the above schemes are: applicable to single pier-simply supported replacement beam connection systems, but for the main line widening location on the bridge, the main line and ramps are often parallel, and there are many piers. During active replacement, multiple piers and the supporting beam form a complex statically indeterminate continuous beam system. During the jacking compensation period, the piers will form a fulcrum effect on the replacement beam, making it impossible to accurately control the internal force load of the replacement main beam. The piers are removed in multiple stages, resulting in a redistribution of the internal force of the replacement beam, thus making it impossible to accurately replace the stress state of the structure. Because the supporting beam and pier nodes of the above traditional schemes are rigid structures, they form statically indeterminate structures. If a small settlement or displacement occurs after the removal of a pier, it will immediately cause a redistribution of the internal force of the entire beam, which may lead to over-reinforcement or cracking of local sections. Therefore, in order to solve the above problems, an improved separated pile foundation replacement structure for main line widening bridges is proposed. Utility Model Content

[0004] The purpose of this utility model is to provide a separate pile foundation replacement structure for a mainline widening bridge, which separates the replacement main longitudinal beam from the original bridge piers. The replacement beam always maintains a simply supported stress state, avoiding the occurrence of statically indeterminate stress state, simplifying the construction process, reducing the technical threshold and rework rate, shortening the construction period, and avoiding damage to the main bridge structure, reducing additional stress, and ensuring structural stability and safety, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a split pile foundation underpinning structure for a mainline widening bridge, comprising an underpinning main longitudinal beam, a support mechanism, and an underpinning mechanism; Two main longitudinal beams are provided, and a gap is formed between two adjacent main longitudinal beams. The replacement mechanism is located in the gap. The support mechanism is provided in two sets, located at both ends of the main longitudinal beam; It also includes bridge piers and the main body of the bridge. The main body of the bridge is located above the main longitudinal beams of the bridge support, and the top of the bridge pier passes through the gap formed between the main longitudinal beams of the bridge support and is connected to the lower surface of the main body of the bridge.

[0006] Preferably, the support mechanism includes pile foundations and pile caps. The pile foundations are cast at both ends below the main longitudinal beam of the underpinning structure. The pile caps are fixed to the top of the pile foundations. Multiple seismic isolation bearings are arranged in a row on the top of the pile caps. The lower surfaces of both ends of the main longitudinal beam of the underpinning structure are connected to the seismic isolation bearings.

[0007] Preferably, the underpinning mechanism includes underpinning beams, and multiple underpinning beams are installed in the gaps formed by the underpinning main longitudinal beams, with the upper ends of the piers located between two adjacent underpinning beams.

[0008] Preferably, the underpinning mechanism further includes a second seismic isolation bearing, which is located at the center of the top of the underpinning beam. Jacks are installed at symmetrical positions at both ends of the underpinning beam, and the tops of the jacks and the second seismic isolation bearing are in contact with the lower surface of the bridge body.

[0009] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model provides a separate pile foundation replacement structure for a bridge with a widened main line. By separating the replacement main longitudinal beam from the original bridge piers, it maintains a simply supported stress state, effectively avoiding the risk of statically indeterminate stress. The stress system is clear and lightweight, avoiding dynamic load changes during pier segment construction and ensuring safe and controllable stress. At the same time, it eliminates the need for rebar connection, avoiding damage to the original piers and saving complex node procedures such as rebar positioning and interface treatment. This simplifies the construction process, reduces reliance on high-precision drilling machines and special rebar adhesives, lowers the technical threshold, avoids rework caused by node construction errors, significantly shortens the construction cycle, and is suitable for projects with tight schedules.

[0010] 2. This utility model provides a separate pile foundation replacement structure for a bridge with a widened main line. A replacement mechanism is installed in the gap formed by two replacement main longitudinal beams. The replacement mechanism enables PLC jacking, which can not only complete the displacement compensation after the bridge replacement, but also ensure the stability of the stress system after the pier is cut. The replacement main longitudinal beams and the original piers can deform relatively independently. With the cooperation of seismic isolation bearing one and seismic isolation bearing two, the deformation can be coordinated to avoid forced synchronous deformation. The additional stress generated by forced coordinated deformation can be coordinated through the free rotation or slight translation of the beams, even in sites prone to uneven settlement such as soft soil foundations, to ensure structural stability. The bridge body does not need to close traffic during the replacement process and supports the simultaneous demolition of multiple piers, which greatly improves construction efficiency.

[0011] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention can be realized and obtained through the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the supporting main longitudinal beam, support mechanism, and supporting mechanism of this utility model. Figure 3 This is an exploded view of the main longitudinal beam and support mechanism of the present invention. Figure 4 This utility model Figure 3 Enlarged schematic diagram of the structure at point A in the middle.

[0013] The following are the labelings in the diagram: 1. Main longitudinal beam underpinning; 2. Supporting mechanism; 21. Pile foundation; 22. Pier cap; 23. Seismic isolation bearing one; 3. Underpinning mechanism; 31. Underpinning tie beam; 32. Seismic isolation bearing two; 33. Jack; 4. Pier; 5. Main body of the bridge. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] This utility model provides, for example Figures 1-4 The diagram shows a mainline widening bridge with a separated pile foundation underpinning structure, which includes an underpinning main longitudinal beam 1, a support mechanism 2, and an underpinning mechanism 3. There are two main longitudinal beams 1 for supporting the replacement, and a gap is formed between two adjacent main longitudinal beams 1. The replacement mechanism 3 is set in the gap. The support mechanism 2 is provided with two sets located at both ends of the main longitudinal beam 1; It also includes pier 4 and bridge body 5. The bridge body 5 is set above the supporting main longitudinal beam 1, and the top of the pier 4 passes through the gap formed between the supporting main longitudinal beam 1 and is connected to the lower surface of the bridge body 5. The main line widening bridge's separated pile foundation underpinning structure uses a double underpinning main longitudinal beam 1 + two-end support mechanisms 2 + underpinning mechanism 3 in the gap as its core framework. The underpinning main longitudinal beam 1 is set in parallel with a reserved gap. The top of the pier 4 passes through the gap and connects to the upper bridge body 5. The load of the bridge body 5 is first transferred to the underpinning main longitudinal beam 1, and then borne by the support mechanisms 2 at both ends of the underpinning main longitudinal beam 1. At the same time, the underpinning mechanism 3 in the gap can assist in bearing and adjustment, forming a collaborative working system of main longitudinal beam bearing + support mechanism 2 force transmission + underpinning mechanism 3 assistance, realizing the underpinning support of the bridge body 5. Since the underpinning main longitudinal beam 1 and the pier 4 are not directly connected, the two can deform relatively independently.

[0016] The structural layout is clear. Through the design of the double-support main longitudinal beam 1 and the gap, a reasonable space is provided for the pier 4 (support column) to pass through and the support mechanism 3 to be installed, avoiding mutual interference between structural components and adapting to the space requirements of the widened main line bridge. The main longitudinal beam 1 is set separately from the pier 4, which avoids the node connection process such as rebar installation from the basic structure, reduces the damage to the original pier 4, and lays the foundation for subsequent independent deformation coordination. The support mechanism 2 is only set at both ends of the main longitudinal beam 1, which simplifies the layout of the support system, reduces the overall structural complexity, and facilitates construction deployment and subsequent maintenance.

[0017] The support structure 2 includes pile foundation 21 and pile cap 22. The pile foundation 21 is cast at both ends below the main longitudinal beam 1. The pile cap 22 is fixed on the top of the pile foundation 21. Multiple seismic isolation bearings 23 are arranged in a row on the top of the pile cap 22. The lower surfaces of both ends of the main longitudinal beam 1 are connected to the seismic isolation bearings 23. The support mechanism 2 serves as the core load-bearing carrier for the main longitudinal beam 1. By casting pile foundations 21 below both ends of the main longitudinal beam 1, the vertical bearing capacity of the pile foundations 21 is used to fix the bottom support. The pile cap 22 at the top of the pile foundation 21 plays the role of load distribution and connection, and evenly transfers the load transmitted by the main longitudinal beam 1 to the pile foundation 21. At the same time, the seismic isolation bearings 23 distributed in an array at the top of the pile cap 22 are connected to the lower surface of the main longitudinal beam 1, which can buffer the vibration transmission between the main longitudinal beam 1 and the pile cap 22, and allow for a small relative displacement between the two. This achieves graded force transmission and vibration reduction coordination of the pile foundation 21 bearing, the pile cap 22 transmitting force, and the seismic isolation bearings 23 buffering. The combined design of pile foundation 21 and pile cap 22 improves the load-bearing stability of support structure 2, effectively supports the load of the main bridge body 5 transmitted by the main longitudinal beam 1, avoids damage to the support structure due to load concentration, and ensures the overall structural safety. The installation of seismic isolation bearing 23 can weaken the impact of vibration on the main longitudinal beam 1 and the support mechanism 2, reduce the additional stress caused by vibration load, and adapt to the small settlement in soft soil foundation and other scenarios, avoiding the risk of cracking of the support system due to rigid connection. The array-distributed seismic isolation bearings 23 can further optimize the load distribution, ensure that the load on both ends of the main longitudinal beam 1 is uniform, and reduce the probability of structural damage caused by local stress concentration.

[0018] The underpinning mechanism 3 includes underpinning beams 31, and multiple underpinning beams 31 are installed in the gap formed by the underpinning main longitudinal beam 1. The upper end of the pier 4 is located between two adjacent underpinning beams 31. The supporting beam 31, as the core load-bearing component within the gap, is installed at intervals along the gaps formed by the supporting main longitudinal beams 1. Space is reserved between adjacent supporting beams 31 for the piers 4 to pass through, which avoids direct contact between the supporting beams 31 and the piers 4, while also allowing the supporting beams 31 to bear part of the load of the bridge body 5. At the same time, the supporting beams 31 form a transverse connection with the double supporting main longitudinal beams 1, which can enhance the transverse stiffness of the overall structure. This achieves the working logic of supporting beams 31 providing auxiliary load-bearing capacity, enhancing transverse stiffness, and having a non-interference layout with the piers 4. The spaced installation of the supporting beams 31 without contact with the piers 4 further strengthens the separated design concept and completely avoids structural interference with the original piers 4. The lateral coordination between the underpinning beam 31 and the double underpinning main longitudinal beam 1 improves the lateral stability of the overall underpinning structure, which is especially suitable for the lateral stiffness requirements caused by the increase in span of the main line widening bridge, and reduces the risk of lateral deformation of the structure. The spaced-out support beams 31 can flexibly adapt to different numbers of piers 4, have good structural adaptability, and facilitate the adjustment of the installation quantity and position according to the actual layout of the bridge piers 4.

[0019] The underpinning mechanism 3 also includes a second seismic isolation bearing 32, which is located at the center of the top of the underpinning beam 31. Jacks 33 are installed at symmetrical positions at both ends of the underpinning beam 31. The tops of the jacks 33 and the second seismic isolation bearing 32 are both in contact with the lower surface of the bridge body 5. The underpinning mechanism 3 adds a second seismic isolation bearing 32 and a jack 33 to the underpinning beam 31. The second seismic isolation bearing 32 is located at the top center of the underpinning beam 31, bearing the conventional vertical load of the bridge body 5 and buffering vibration. The jacks 33, which are symmetrically installed at both ends of the underpinning beam 31, can be synchronously lifted or compensated for displacement through PLC control. When the bridge body 5 settles or displaces due to the underpinning, the jacks 33 can adjust their height in real time, working together with the second seismic isolation bearing 32 to maintain the horizontal and force balance of the bridge body 5, forming a dual underpinning guarantee system of conventional load-bearing and vibration reduction by the second seismic isolation bearing 32 and dynamic adjustment and compensation by the jacks 33. The combination of the second seismic isolation bearing 32 and the jacks 33 not only meets the vibration reduction requirements under conventional loads, but also copes with displacement deviations during the underpinning process, realizing the dual functions of static load-bearing and dynamic adjustment, and greatly improving the force controllability of the underpinning structure. The symmetrically distributed jacks 33 can be synchronously controlled by PLC to ensure that the bridge main body 5 is subjected to uniform force when it is lifted or compensated, avoid additional stress caused by improper local adjustment, and ensure the structural safety of the bridge main body 5. The displacement compensation function of the jacks 33 does not require traffic closure and can be completed under the normal traffic conditions of the bridge, reducing the impact on traffic. At the same time, in conjunction with the damping effect of the seismic isolation bearing 2 32, it further reduces the structural risks during construction and use. Both the seismic isolation bearing 32 and the jack 33 are directly attached to the lower surface of the bridge body 5, resulting in a short and direct force transmission path, avoiding energy loss and stress attenuation during load transmission, and improving load transmission efficiency.

[0020] In practical application, firstly, to avoid interference from the surrounding soil, pile foundations 21 are driven around the pier 4 to be replaced, and a pile cap 22 is poured on top of the pile foundations 21. Then, seismic isolation bearings 23 are installed. Subsequently, when pouring concrete to replace the main longitudinal beam 1, a strict gap is reserved between it and the original column. The two ends of the main longitudinal beam 1 are supported on the newly poured pile cap 22 and are not connected to the original pier 4. This separate force-bearing method is implemented from the construction stage, which avoids complex node treatments such as rebar installation, reduces the technical threshold and rework rate, and ensures that the main longitudinal beam 1 and the pier 4 are independently stressed. After the strength of the main longitudinal beam 1 reaches the standard, PLC-controlled jacks 33 (displacement compensation lifting devices) are installed on the replacement tie beam 31. When cutting the connection between the original pier 4 and the main bridge body 5, the jacks are actively controlled. 33 Real-time settlement compensation relies on the working principle of PLC jacking and dynamic adjustment to keep the bridge deck elevation unchanged, without closing traffic, greatly improving construction efficiency. At the same time, through the synergy of jack 33 and seismic isolation bearing 2 32, vibration transmission is buffered, additional stress is reduced, and the advantages of safe and controllable stress are further enhanced. Finally, the overburden is removed and the old pier 4 is demolished. At this time, the replacement structure fully bears the load of the main bridge body 5 through the complete system of "supporting the main longitudinal beam 1, supporting mechanism 2 (pile foundation 21 + pile cap 22 + seismic isolation bearing 23) graded force transmission + replacement mechanism 3 auxiliary adjustment". This achieves the ultimate goal of pile foundation 21 replacement and protects the original pier 4 and the main bridge body 5 throughout the process, fully meeting the core requirements of "simplification, adaptability and safety" of the replacement project.

[0021] Although embodiments of the present 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 present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A separate pile foundation (21) underpinning structure for a mainline widening bridge, characterized in that: It includes the main longitudinal beam (1), the support mechanism (2) and the replacement mechanism (3); There are two main longitudinal beams (1) for supporting the load, and a gap is formed between two adjacent main longitudinal beams (1). The load-bearing mechanism (3) is set in the gap. The support mechanism (2) is provided with two sets located at both ends of the main longitudinal beam (1); It also includes a pier (4) and a bridge body (5), the bridge body (5) being positioned above the supporting main longitudinal beam (1), and the top of the pier (4) passing through the gap formed between the supporting main longitudinal beam (1) and connecting to the lower surface of the bridge body (5).

2. The mainline widening bridge separated pile foundation (21) underpinning structure according to claim 1, characterized in that: The support mechanism (2) includes a pile foundation (21) and a pile cap (22). The pile foundation (21) is cast at both ends below the main longitudinal beam (1). The pile cap (22) is fixed on the top of the pile foundation (21). Multiple seismic isolation bearings (23) are arranged in a row on the top of the pile cap (22). The lower surfaces of both ends of the main longitudinal beam (1) are connected to the seismic isolation bearings (23).

3. The mainline widening bridge separated pile foundation (21) underpinning structure according to claim 2, characterized in that: The underpinning mechanism (3) includes underpinning beams (31), and multiple underpinning beams (31) are installed in the gap formed by the underpinning main longitudinal beam (1). The upper end of the pier (4) is located between two adjacent underpinning beams (31).

4. The mainline widening bridge separated pile foundation (21) underpinning structure according to claim 3, characterized in that: The underpinning mechanism (3) also includes a second seismic isolation bearing (32), which is located at the center of the top of the underpinning beam (31). Jacks (33) are installed at symmetrical positions at both ends of the underpinning beam (31). The tops of the jacks (33) and the second seismic isolation bearing (32) are both in contact with the lower surface of the bridge body (5).

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