Historic building foundation settlement treatment method and underpinning structure
Patent Information
- Application Number
- CN202611445650.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-17
- Publication Date
- 2026-10-23
AI Technical Summary
[0008]本发明的目的在于，克服现有技术的缺陷，提供一种历史建筑地基沉降治理方法及托换结构，有效解决现有治理技术扰动大、整体受力不均、临时支撑与永久结构脱节、加固不可逆的问题
[0029]本发明的有益效果是：辅助支撑组件的内端伸入地基支撑体底部中心承托地基支撑体，临时桩在辅助支撑组件下方支撑，斜拉梁将临时桩与辅助支撑组件远端拉结形成稳定三角体系；配重板以临时桩为支点对辅助支撑组件远端施加预压力，使其内端在基底开挖前即提前、稳定地承接建筑上部荷载，有效规避基底开挖卸荷带来的结构上浮、开裂、倾斜风险；全过程无需在墙体开洞、无需千斤顶顶升，相比托盘梁顶升类技术对脆弱历史建筑的扰动显著降低。四角斜向成对基础桩形成稳定点状承力体系，拐角短横梁与四边长横梁锚固成包覆地基支撑体底部的闭合框型承台结构，将建筑上部荷载沿四边整体拉结、均匀分散至全部桩基，整体受力性能远优于单点加固及夹壁梁-抬梁体系。第二钢筋延伸网与长横梁直接绑扎咬合锚固、第一钢筋延伸网与外围加固混凝土锚固成整体，临时支撑单元免二次植筋即转化为永久加固结构与外围防渗围护结构的组成部分，形成双重加固体系，荷载转换平稳，缩短工期。全部新增构件布置于历史建筑原有结构外围及地基支撑体底部空隙处，不凿除、不破坏原有台基、条石、青砖本体，后期可整体切割分离拆除，完全符合文物修缮最小干预及可逆性原则。双液浆低压注浆封堵渗水通道、填充隐蔽空洞，填充混凝土连续浇筑形成连续整体面支撑，配合外围防渗排水体系，永久性隔断水文诱因，病害复发概率低。
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Figure CN122960183A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of building reinforcement technology, specifically relating to a method for treating foundation settlement of historical buildings and a replacement structure. Background Technology
[0002] Most historical buildings are brick-wood or brick-stone structures, and have been built for a long time. Due to changes in the weak foundation layer, groundwater seepage, and long-term load, uneven foundation settlement is common, which in turn leads to problems such as wall cracks and building tilting.
[0003] Existing foundation settlement control technologies have the following main shortcomings: The pallet beam lifting technology requires the fabrication of pallet beams on both the inner and outer sides of the building foundation walls, drilling holes in the walls, inserting steel pipes and prestressed tendons, and coordinating with the pier beam and jacks to carry out the overall lifting. Historical buildings have low structural strength and poor integrity, and the drilling and lifting operations cause significant disturbance. Furthermore, the static pressure piles at individual points are not subjected to uniform stress, making it impossible to eliminate overall differential settlement.
[0004] Centralized support structures require the installation of wall-clamping beams on both sides of the lower part of the building wall to clamp the wall, and the transfer of load by lifting beams that pass through the wall at intervals. The installation of wall-clamping beams and lifting beams requires clamping the wall and openings through the wall, which damages the wall structure and facade of the historical building.
[0005] Functional upgrade construction methods require the installation of a pallet structure on the wall beam, a foundation pit support structure, and overall jacking and large-area excavation. The process is complex, and the jacking and large-scale excavation process poses significant disturbance and safety risks to historical buildings.
[0006] The existing temporary support and permanent support structure are disconnected from each other, and the load transfer after the temporary support is removed is prone to cause secondary deformation; moreover, most reinforcement schemes require the removal of the original stone and brick foundations, permanently altering the original structure of the cultural relics, which does not meet the reversibility requirements of cultural relic restoration.
[0007] In summary, existing treatment techniques are insufficient to meet the multiple requirements of ensuring the structural safety of historical buildings, protecting the original appearance of cultural relics, minimizing construction disturbance, ensuring reversible reinforcement, and providing long-term seepage prevention. There is an urgent need for a comprehensive foundation settlement treatment technology that does not require drilling through walls or opening holes, does not require jacking, bears the load as a whole, allows temporary supports to be converted into permanent structures, and is reversible and removable. Summary of the Invention
[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for treating foundation settlement of historical buildings and a replacement structure, which effectively solves the problems of large disturbance, uneven overall stress, disconnection between temporary support and permanent structure, and irreversible reinforcement in the existing treatment technology.
[0009] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention proposes a method for treating foundation settlement of historical buildings, comprising the following steps: S1. Pile foundation construction: Construct a set of foundation piles on the outer side of each of the four corners of the historical building. Each set of foundation piles includes two foundation piles arranged at an angle. The two foundation piles in the same set are arranged symmetrically along the angle bisector of the corner. The pile tip penetrates the soft soil layer and is embedded in the stable bearing layer. S2. Construction of Temporary Support System: Several temporary piles are constructed on the outside of the historical building; an auxiliary support assembly is constructed between the temporary piles and the foundation support at the bottom of the historical building. The auxiliary support assembly is a cast-in-place concrete beam, one end of which extends to the bottom of the foundation support and supports it upwards, while the other end extends away from the historical building. The temporary piles are located below the auxiliary support assembly and support it. The end of the auxiliary support assembly away from the historical building is provided with a first outward-extending steel reinforcement mesh, and the two sides of the auxiliary support assembly located below the historical building are respectively provided with a second outward-extending steel reinforcement mesh. A cast-in-place cable-stayed beam is constructed, one end of which is connected to the temporary piles, and the other end of which is connected to the end of the auxiliary support assembly away from the historical building. A counterweight plate is installed at the end of the auxiliary support assembly away from the historical building, and a preload is applied to the auxiliary support assembly through the counterweight plate, so that the end of the auxiliary support assembly supporting the foundation support bears the upper load of the historical building. S3. Foundation Excavation: After the auxiliary support components are stably stressed, the soil under the foundation support body is excavated in layers and sections to form the working space. S4. Construction of short crossbeams at corners: short crossbeams are cast in place at the bottom of the foundation support structure at each corner of the historical building. The two ends of the short crossbeams are anchored to the top of the two foundation piles at the same corner, and the top surface of the short crossbeams is close to the bottom surface of the foundation support structure. S5. Construction of long horizontal beams on four sides: Long horizontal beams are cast in place along the four sides of the historical building. The two ends of the long horizontal beams are anchored to the short horizontal beams at the adjacent corners to form a closed frame-type foundation structure. When casting the long horizontal beams, the second steel reinforcement extension mesh is anchored inside the long horizontal beams. S6. Base filling: Seal the voids in the base and pour filling concrete. The filling concrete and the frame-type foundation structure are combined to form a composite surface support. S7. External reinforcement construction: Remove the counterweight plate, and pour external reinforcement concrete at the end of the auxiliary support component away from the historical building. The external reinforcement concrete covers the first steel reinforcement extension mesh, and after solidification, it forms an external reinforcement layer. The first steel reinforcement extension mesh is anchored in the external reinforcement layer.
[0010] Further, in step S2, when constructing the auxiliary support component, a trench is excavated from the side away from the historical building towards the historical building. The trench passes through the temporary pile, and the end of the trench extends to the bottom center of the foundation support body. The excavation depth of the trench extends to the bottom surface of the foundation support body. A steel mesh is tied in the trench and on top of the temporary pile, and a formwork is set up. Concrete is poured in place in the formwork to form the auxiliary support component. When tying the steel mesh, the first steel extension mesh and the second steel extension mesh are reserved. The counterweight plate is assembled after the auxiliary support component reaches the design strength.
[0011] Furthermore, in step S1, the foundation piles are micropiles with a borehole diameter of 180mm to 250mm, an inclination angle of 15° to 45°, and the depth of the pile tip embedded in the stable bearing layer is not less than 1.8m; the foundation piles are cast with C30 micro-expansion concrete, and the entire process uses a silent drilling machine with low-speed rotation to form the hole, prohibiting impact drilling; the four sets of corner foundation piles are constructed in batches at intervals; the temporary piles are also constructed using a silent low-speed drilling process.
[0012] Furthermore, in step S4, after the foundation piles reach the design strength, the top of the foundation piles is roughened and reinforced with rebar, and then the short crossbeam is cast. The short crossbeam is cast with C35 reinforced concrete and has a cross-sectional dimension of 350mm×400mm. A flexible buffer layer is laid between the top surface of the short crossbeam and the bottom surface of the foundation support. The flexible buffer layer avoids wall cracking and foundation lifting damage caused by rigid jacking during the casting and vibration process.
[0013] Furthermore, in step S5, the long crossbeam is constructed by segmented casting of C35 reinforced concrete with a cross-sectional dimension of 400mm×450mm; the main reinforcement bars at both ends of the long crossbeam are embedded and anchored inside the corner short crossbeam, and the stirrups at the anchoring ends are densely arranged so that the short crossbeam and the long crossbeam form a closed frame-type foundation structure for overall stress.
[0014] Furthermore, in step S6, before pouring the filling concrete, the base is pre-treated by grouting: a cement-water glass double-liquid grout is used, and the grouting pressure is controlled at 0.5MPa to 2.0MPa for low-pressure permeation grouting, which prioritizes sealing groundwater leakage channels and filling hidden cavities in the base. After the grout solidifies to form a grouting reinforcement layer, the filling concrete pouring construction is carried out. The filling concrete is C25 plain concrete, which is continuously poured in a large area, and the pouring thickness is controlled at 300mm to 800mm. The interface between the filling concrete and the long crossbeam is roughened to ensure a tight bond between the old and new concrete and form a continuous integral surface support.
[0015] Furthermore, the foundation piles, short crossbeams, long crossbeams, auxiliary support components, filling concrete, and external reinforcement layers are all arranged on the periphery of the original structure of the historical building or in the bottom gaps of the foundation support, without chiseling away or damaging the original platform, stone strips, and blue brick structure of the historical building, and the newly added reinforcement structure can be completely demolished later.
[0016] Furthermore, before step S1, there are also preliminary investigation and temporary protection steps: conduct disease detection and geotechnical investigation on historical buildings, set up settlement monitoring points, seal the building seepage channels, and lay out the location and center of the foundation support.
[0017] Furthermore, throughout the construction process, high-precision level instruments, wall crack gauges, deep soil displacement sensors, and foundation pressure sensors are deployed to monitor the settlement of the historical building, the width of wall cracks, soil displacement, and changes in foundation stress in real time. If deformation exceeds the standard or cracks expand, work is immediately stopped and construction parameters are adjusted.
[0018] Furthermore, after step S7, structural repair and style restoration steps are also included: the original cracks in the walls and foundation support of the historical building are repaired and restored using traditional proportioned mortar, and the exterior facade and ground of the construction area are restored in an antique style; at the same time, the drainage system, blind ditch and interception system around the building are modified to build a long-term seepage prevention and drainage system.
[0019] Furthermore, step S7 is followed by a long-term settlement monitoring and acceptance process: settlement monitoring is conducted every 7 days for the first 6 months after reinforcement is completed, and every 30 days from the 7th to the 24th month; when the overall settlement rate of the historical building is stable and not greater than 0.1 mm / d, there are no new cracks and the uneven settlement difference no longer increases, the settlement treatment is deemed to have met the standards.
[0020] Furthermore, the counterweight plate includes several prefabricated counterweight blocks stacked on top of the auxiliary support assembly, and the counterweight plate and the auxiliary support assembly are detachably assembled.
[0021] Furthermore, the cable-stayed beam is a cast-in-place reinforced concrete beam, and the cable-stayed beam is integrally cast and connected to the top of the temporary piles and the auxiliary support components.
[0022] Secondly, this invention also proposes a foundation settlement treatment and underpinning structure for historical buildings, comprising: four sets of foundation piles, respectively located on the outer sides of the four corners of the historical building; each set of foundation piles includes two obliquely arranged foundation piles, with the two foundation piles in the same set symmetrically arranged along the angle bisector of the corner; the pile tips of the foundation piles penetrate the weak soil layer and embed into the stable bearing layer; four short horizontal beams, respectively located at the bottom of the foundation support structure at each corner of the historical building; the two ends of the short horizontal beams are respectively anchored to the pile tops of the two foundation piles at the same corner; the top surface of the short horizontal beams is in close contact with the bottom surface of the foundation support structure; four long horizontal beams, set along the four sides of the historical building; the two ends of the long horizontal beams are respectively anchored to the short horizontal beams at adjacent corners; the four long horizontal beams and the four short horizontal beams together form a closed frame-type foundation structure; several temporary support units, each temporary support unit including temporary piles, auxiliary support components, and inclined tie beams; auxiliary support groups. The component is a cast-in-place concrete ground beam, one end of which extends to the bottom of the foundation support and supports the foundation support upwards, while the other end extends away from the historical building; temporary piles are set on the outside of the historical building, located below the auxiliary support component and supporting the auxiliary support component; one end of the cable-stayed beam is connected to the temporary pile, and the other end is connected to the end of the auxiliary support component away from the historical building; the end of the auxiliary support component away from the historical building is provided with a first outward-extending steel reinforcement mesh, and the two sides of the auxiliary support component located below the historical building are respectively provided with second outward-extending steel reinforcement meshes, which are anchored in the long crossbeam; an outer reinforcement layer is set at the end of the auxiliary support component away from the historical building, and the outer reinforcement layer covers the first steel reinforcement mesh, which is anchored in the outer reinforcement layer; and infill concrete is used to fill the base voids inside the frame-type foundation structure.
[0023] Furthermore, a flexible buffer layer is laid between the top surface of the short crossbeam and the bottom surface of the foundation support; the short crossbeam is a C35 reinforced concrete beam with a cross-sectional dimension of 350mm×400mm; the long crossbeam is a C35 reinforced concrete beam with a cross-sectional dimension of 400mm×450mm, the main reinforcement bars at both ends of the long crossbeam are embedded in the short crossbeam for anchorage, and the stirrups at the anchorage ends are densely arranged.
[0024] Furthermore, a grouting reinforcement layer is provided below the filling concrete, and the grouting reinforcement layer is a cement-water glass double-liquid grout solidification body; the filling concrete is C25 plain concrete with a pouring thickness of 300mm to 800mm, and the interface between the filling concrete and the long crossbeam is a roughened interface.
[0025] Furthermore, the foundation piles, short crossbeams, long crossbeams, auxiliary support components, outer reinforcement layer and filling concrete are all arranged on the periphery of the original structure of the historical building and in the bottom gap of the foundation support, and are independent of and separable from the original structure of the historical building.
[0026] Furthermore, the cable-stayed beam is a cast-in-place reinforced concrete beam, and the cable-stayed beam is integrally cast and connected to the top of the temporary piles and the auxiliary support components.
[0027] Furthermore, the foundation pile is a micropile with a bore diameter of 180mm to 250mm, an inclination angle of 15° to 45°, a depth of not less than 1.8m where the pile tip is embedded in the stable bearing layer, and the pile body is a C30 micro-expansion concrete pile body.
[0028] It should be noted that the foundation support body mentioned in this invention refers to the original foundation support structure at the bottom of the historical building that directly supports the load of the upper part of the building, such as a brick and stone platform, a strip stone foundation, or a blue brick foundation; the temporary support unit undertakes the function of temporary support during the construction phase, and its components are permanently retained after the restoration is completed, and are anchored to the outer reinforcement layer and the long crossbeam through the first steel reinforcement extension mesh and the second steel reinforcement extension mesh respectively to form an integral whole, and are transformed into a component of the permanent reinforcement structure.
[0029] The beneficial effects of this invention are as follows: the inner end of the auxiliary support component extends into the center of the bottom of the foundation support body to support the foundation support body; temporary piles are supported below the auxiliary support component; and the inclined tie beams connect the temporary piles and the far end of the auxiliary support component to form a stable triangular system; the counterweight plate applies pre-pressure to the far end of the auxiliary support component with the temporary piles as fulcrums, so that its inner end can bear the upper load of the building in advance and stably before the foundation excavation, effectively avoiding the risks of structural floating, cracking, and tilting caused by unloading during foundation excavation; the entire process does not require opening holes in the wall or lifting with jacks, significantly reducing the disturbance to fragile historical buildings compared to pallet beam lifting technologies. The four corner diagonally paired foundation piles form a stable point-bearing system, and the corner short crossbeams and the four side long crossbeams are anchored to form a closed frame-type foundation structure covering the bottom of the foundation support body, which connects the upper load of the building along the four sides and evenly distributes it to all pile foundations. The overall stress performance is far superior to single-point reinforcement and the wall beam-lifting beam system. The second steel reinforcement extension mesh is directly tied and anchored to the long crossbeam, while the first steel reinforcement extension mesh is anchored to the outer reinforcing concrete to form a whole. The temporary support unit is transformed into a component of the permanent reinforcement structure and the outer seepage prevention and protection structure without the need for secondary rebar installation, forming a dual reinforcement system. This ensures smooth load transfer and shortens the construction period. All new components are placed on the outer perimeter of the original structure of the historical building and in the gaps at the bottom of the foundation support, without chiseling or damaging the original platform, stone strips, or blue bricks. They can be cut and separated as a whole for later removal, fully complying with the principles of minimal intervention and reversibility in cultural relic restoration. Low-pressure grouting with dual-liquid grout seals seepage channels and fills hidden cavities. The filling concrete is continuously poured to form a continuous integral surface support. Combined with the outer seepage prevention and drainage system, this permanently isolates hydrological causes, resulting in a low probability of disease recurrence. Attached Figure Description
[0030] Figure 1 This is a flowchart illustrating the method for treating foundation settlement of historical buildings according to the present invention. Figure 2 This is a top view of the historical building, foundation piles, short crossbeams, long crossbeams, and auxiliary support components of the present invention. Figure 3 This is a partial structural diagram of the corner of the historical building of this invention; Figure 4 for Figure 3 A schematic diagram of the structure in which the first steel reinforcement mesh is anchored within the outer reinforcement layer; Figure 5 This is a schematic diagram showing the distribution structure of the first and second steel reinforcement extension meshes at both ends of the auxiliary support component of the present invention. Figure 6 This is a schematic diagram illustrating the construction process of the underpinning structure at a corner of a historical building according to the present invention.
[0031] The markings in the diagram are as follows: 1-Foundation pile; 2-Short crossbeam; 3-Long crossbeam; 4-Temporary pile; 5-Auxiliary support assembly; 51-First steel reinforcement extension mesh; 52-Second steel reinforcement extension mesh; 6-Cable tie beam; 7-Counterweight plate; 8-External reinforcement layer; 10-Historical building; 11-Foundation support structure. Detailed Implementation
[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0033] like Figure 1 As shown, the method for treating foundation settlement of historical buildings according to the present invention includes the following steps: S1. Pile foundation construction; S2, Construction of temporary support system; S3. Foundation excavation; S4. Construction of short crossbeams at corners; S5, Construction of four-sided long crossbeams; S6, Base filling; S7. External reinforcement construction.
[0034] It should be noted that the method for treating foundation settlement of historical buildings in this invention can be understood as a construction method for a replacement structure for treating foundation settlement of historical buildings. The following is in conjunction with... Figures 2-6 This paper provides a detailed explanation of the historical building foundation settlement treatment underpinning structure and its construction method (or historical building foundation settlement treatment method) of the present invention.
[0035] First, conduct disease detection and geotechnical engineering investigation on historical building 10, set up initial settlement monitoring points, and determine the quantity, location and center of foundation support 11 (brick and stone platform, strip stone foundation or blue brick foundation, etc.); seal the building seepage channels, provide temporary support for weak parts of the wall, and complete the layout and positioning.
[0036] Corresponding to step S1: Construct a set of two foundation piles 1 on the outer side of each of the four corners of the historical building 10, symmetrically arranged diagonally along the angle bisector of the corner, with an inclination angle of 15° to 45°. The foundation piles 1 are micropiles with a borehole diameter of 180mm to 250mm, with the pile tip penetrating the soft soil layer and embedding into the stable bearing layer, with an embedding depth of not less than 1.8m; the entire process uses a silent drilling rig with low-speed rotation to form the hole, and impact drilling is prohibited. The piles are cast with C30 micro-expansion concrete; the four sets of corner pile foundations are constructed in batches at intervals to minimize vibration and soil displacement disturbance.
[0037] Corresponding to step S2: Temporary piles 4 are constructed on the outside of the historical building 10, at positions corresponding to the foundation supports 11 to be supported. The temporary piles 4 are also constructed using a quiet, low-speed drilling process. A trench is excavated from the side furthest from the historical building 10 towards it, passing through the temporary piles 4. The end of the trench extends to the bottom center of the foundation support 11, and the excavation depth extends to the bottom surface of the foundation support 11. A steel mesh is tied inside the trench and on top of the temporary piles 4, and a formwork is installed. Cast-in-place concrete is then used to form the auxiliary support assembly 5. The auxiliary support assembly 5 is a cast-in-place concrete beam: one end extends to the bottom of the foundation support 11 and supports it upwards, while the other end extends away from the historical building 10. The temporary piles 4 are located below the auxiliary support assembly 5 and support it; the two are connected as a whole by the steel mesh.
[0038] When tying the steel mesh, a first steel extension mesh 51 extending outward is reserved at the end of the auxiliary support component 5 away from the historical building 10, and a second steel extension mesh 52 extending outward is reserved on both sides of the section of the auxiliary support component 5 located below the historical building 10.
[0039] Subsequently, a cast-in-place cable-stayed beam 6 is constructed. The cable-stayed beam 6 is a cast-in-place reinforced concrete beam, with one end connected to the top of the temporary pile 4 and the other end connected to the end of the auxiliary support component 5 furthest from the historical building 10. The cable-stayed beam 6, the top of the temporary pile 4, and the auxiliary support component 5 are integrally cast and connected, forming a stable triangular tie system. After the auxiliary support component 5 solidifies and reaches its design strength, a counterweight plate 7 is installed at its top end furthest from the historical building 10. The counterweight plate 7 is composed of several prefabricated counterweight blocks stacked together and is detachably assembled with the auxiliary support component 5. The counterweight plate 7 applies a lever-type preload to the auxiliary support component 5 with the temporary pile 4 as a fulcrum, enabling the end of the auxiliary support component 5 supporting the foundation support 11 to pre-load the upper load of the historical building 10 stably, thus avoiding the structural deformation risk caused by subsequent foundation excavation and unloading.
[0040] Corresponding step S3: After all auxiliary support components 5 are assembled with counterweight plates 7 and stabilized under force, the soil under the foundation support body 11 is excavated in layers and sections to reserve working space for the subsequent replacement of short crossbeams 2 and long crossbeams 3.
[0041] Corresponding to step S4: After the foundation piles 1 reach their design strength, the pile tops are roughened and rebar is installed. C35 reinforced concrete short beams 2, with a cross-sectional dimension of 350mm × 400mm, are cast in place at the bottom of each corner foundation support 11. Both ends of each short beam 2 are anchored to the tops of the two foundation piles 1 at the same corner. A flexible buffer layer is laid between the top surface of the short beams 2 and the bottom surface of the foundation support 11, ensuring the short beams 2 are in close contact with the bottom surface of the foundation support 11 while avoiding wall cracking and foundation lifting damage caused by rigid jacking during pouring and vibration. The four short beams 2 form independent point-like support at the four corners of the building, initially curbing foundation settlement.
[0042] Corresponding to step S5: Cast C35 reinforced concrete long horizontal beams 3 in sections along the four sides of the historical building 10, with a cross-sectional dimension of 400mm × 450mm. The main reinforcement bars at both ends of the long horizontal beams 3 are embedded and anchored inside the short horizontal beams 2 at adjacent corners. The stirrups at the anchoring ends are densely arranged, so that the four long horizontal beams 3 and the four short horizontal beams 2 form a closed frame-type foundation structure that works together to bear the load. During the casting of the long horizontal beams 3, the second steel reinforcement extension mesh 52 reserved on both sides of the auxiliary support component 5 extends into the casting range of the long horizontal beams 3 and is tied to the reinforcement bars of the long horizontal beams 3. After the casting is completed, the second steel reinforcement extension mesh 52 is anchored inside the long horizontal beams 3, and each temporary support unit is thus connected to the frame-type foundation structure to form an integrated load-bearing system.
[0043] Corresponding to step S6: First, perform grouting pretreatment on the base: Use cement-water glass double liquid grout, and control the grouting pressure at 0.5MPa~2.0MPa for low-pressure permeation grouting, to prioritize sealing groundwater leakage channels and filling hidden cavities in the base. After the grout solidifies, a grouting reinforcement layer is formed. Then, roughen the interface between the filling concrete and the long crossbeam 3, and continuously pour a large area of C25 plain concrete to form the filling concrete with a thickness of 300mm~800mm. The new and old concrete are tightly bonded to form a continuous and integral pile-beam-fill composite surface support to prevent the base from sinking and settling again.
[0044] Corresponding to step S7: After the frame-type foundation structure and the filling concrete have stabilized under stress, remove the counterweight plate 7; cast a large area of external reinforcement concrete at the end of the auxiliary support component 5 away from the historical building 10. This external reinforcement concrete covers the first steel reinforcement mesh 51, and after solidification, it forms an external reinforcement layer 8. The first steel reinforcement mesh 51 is anchored within the external reinforcement layer 8, thereby transforming each temporary support unit into a component of the permanent seepage-proof retaining structure, forming a double reinforcement system. It should be noted that the external reinforcement concrete only covers the area where the first steel reinforcement mesh 51 is located, and is not poured around the entire outer perimeter of the auxiliary support component 5.
[0045] Step S7 is followed by structural repair and style restoration steps: the original cracks in the walls and foundation support 11 of the historical building 10 are repaired and restored using traditional proportioned mortar, and the facade and ground of the construction area are restored in an antique style to restore the original style of the historical building; at the same time, the drainage system, blind ditch and interception system around the building are modified to construct a two-layer long-term seepage prevention and drainage system on the surface and underground, permanently blocking the hydrological factors that cause rainwater and groundwater to seep into the foundation softening soil layer.
[0046] Settlement monitoring will be conducted every 7 days for the first 6 months after reinforcement is completed, and every 30 days from the 7th to the 24th month. When the overall settlement rate of the historical building 10 is stable and no greater than 0.1 mm / d, there are no new cracks and the uneven settlement difference no longer increases, the settlement treatment is deemed to have met the standards, and the overall treatment acceptance and project data archiving are completed.
[0047] Throughout the construction process, high-precision level instruments, wall crack gauges, deep soil displacement sensors, and foundation pressure sensors are deployed to monitor building settlement, wall crack width, soil displacement, and foundation stress changes in real time. If deformation exceeds the standard or cracks expand, work is immediately stopped and construction parameters are adjusted.
[0048] The foundation pile 1, short crossbeam 2, long crossbeam 3, auxiliary support components 5, filling concrete, and outer reinforcement layer 8 of this invention are all arranged on the periphery of the original structure of the historical building 10 or in the bottom gap of the foundation support 11. They are independent of the original structure and can be separated without chiseling or damaging the original platform, stone strips, and blue brick body structure. If demolition is required in the future, the newly added reinforcement structure can be cut and separated along the surface of the original structure and removed as a whole, which meets the principle of minimal intervention and reversible construction for cultural relic protection.
[0049] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.
Claims
1. A method for treating foundation settlement of historical buildings, characterized in that, Includes the following steps: S1. Pile foundation construction: A set of foundation piles is constructed on the outer side of the four corners of the historical building. Each set of foundation piles includes two foundation piles. The two foundation piles in the same set are symmetrically arranged along the angle bisector of the corner. The pile tip of the foundation pile penetrates the soft soil layer and is embedded in the stable bearing layer. S2. Construction of Temporary Support System: Several temporary piles are constructed on the outside of the historical building; an auxiliary support assembly is constructed between the temporary piles and the foundation support at the bottom of the historical building. The auxiliary support assembly is a cast-in-place concrete beam, one end of which extends to the bottom of the foundation support and supports it upwards, and the other end extends away from the historical building. The temporary piles are located below the auxiliary support assembly and support it. The auxiliary support assembly has a first outward-extending steel reinforcement mesh at the end away from the historical building, and second outward-extending steel reinforcement meshes on both sides of the section of the auxiliary support assembly below the historical building. A cast-in-place cable-stayed beam is constructed, one end of which is connected to the temporary piles, and the other end of which is connected to the end of the auxiliary support assembly away from the historical building. A counterweight plate is installed at the end of the auxiliary support assembly away from the historical building, and a preload is applied to the auxiliary support assembly through the counterweight plate, so that the end of the auxiliary support assembly supporting the foundation support bears the upper load of the historical building. S3. Foundation Excavation: After the auxiliary support components are stably stressed, the soil under the foundation support body is excavated in layers and sections to form the working space. S4. Construction of short crossbeams at corners: short crossbeams are cast in place at the bottom of the foundation support structure at each corner of the historical building. The two ends of the short crossbeams are respectively anchored to the top of the two foundation piles at the same corner, and the top surface of the short crossbeams is close to the bottom surface of the foundation support structure. S5. Construction of the four-sided long horizontal beams: Long horizontal beams are cast in place along the four sides of the historical building. The two ends of the long horizontal beams are respectively anchored to the short horizontal beams at the adjacent corners. The four long horizontal beams and the four short horizontal beams together form a closed frame-type foundation structure. When casting the long horizontal beams, the second steel reinforcement extension mesh is anchored inside the long horizontal beams. S6. Base filling: The base voids under the foundation support are sealed and filled with concrete. The filling concrete is combined with the frame-type foundation structure to form a composite surface support. S7. External reinforcement construction: Remove the counterweight plate, and pour external reinforcement concrete at the end of the auxiliary support component away from the historical building. The external reinforcement concrete covers the first steel reinforcement extension mesh, and after solidification, it forms an external reinforcement layer. The first steel reinforcement extension mesh is anchored in the external reinforcement layer.
2. The method for treating foundation settlement of historical buildings according to claim 1, characterized in that, In step S2, when constructing the auxiliary support component, a trench is excavated from the side away from the historical building towards the historical building. The trench passes through the temporary pile, and the end of the trench extends to the bottom center of the foundation support body. The excavation depth of the trench extends to the bottom surface of the foundation support body. A steel mesh is tied in the trench and on top of the temporary pile, and a formwork is set up. Concrete is poured in place in the formwork to form the auxiliary support component. When tying the steel mesh, the first steel extension mesh and the second steel extension mesh are reserved. The counterweight plate is assembled after the auxiliary support component reaches the design strength.
3. The method for treating foundation settlement of historical buildings according to claim 1, characterized in that, In step S1, the foundation piles are micropiles, the pile bodies are cast with micro-expansion concrete, and the entire process is carried out by a silent drilling machine with low-speed rotation. The four sets of foundation piles are constructed in batches at intervals.
4. The method for treating foundation settlement of historical buildings according to claim 1, characterized in that, In step S4, a flexible buffer layer is laid between the top surface of the short crossbeam and the bottom surface of the foundation support. The flexible buffer layer avoids wall cracking and foundation lifting damage caused by rigid jacking during the pouring and vibration process.
5. The method for treating foundation settlement of historical buildings according to claim 1, characterized in that, In step S5, the long crossbeam is cast in sections; the main reinforcement bars at both ends of the long crossbeam are embedded and anchored inside the corner short crossbeam, and the stirrups at the anchoring ends are densely arranged so that the short crossbeam and the long crossbeam form a closed frame-type foundation structure for overall stress.
6. The method for treating foundation settlement of historical buildings according to claim 1, characterized in that, In step S6, before pouring the filling concrete, the base is pre-treated by grouting: low-pressure permeation grouting is carried out using cement-water glass double liquid grout to first seal the groundwater leakage channels and fill the hidden cavities in the base. After the grout solidifies to form a grouting reinforcement layer, the filling concrete pouring construction is carried out. The filling concrete is poured continuously over a large area as a whole. The interface between the filling concrete and the long crossbeam is roughened to ensure that the new and old concrete are tightly bonded and form a continuous integral surface support.
7. The method for treating foundation settlement of historical buildings according to claim 1, characterized in that, Step S7 is followed by structural repair and style restoration steps: the original cracks in the walls and foundation supports of the historical building are repaired and restored using traditional mortar mixes, and the exterior facade and ground of the construction area are restored in an antique style.
8. A foundation settlement treatment and underpinning structure for historical buildings, characterized in that, include: Four sets of foundation piles are set on the outside of the four corners of the historical building. Each set of foundation piles includes two foundation piles. The two foundation piles in the same set are symmetrically arranged along the angle bisector of the corner. The pile ends of the foundation piles penetrate the soft soil layer and are embedded in the stable bearing layer. Four short crossbeams are installed at the bottom of the foundation support structure at each corner of the historical building. The two ends of the short crossbeams are anchored to the top of the two foundation piles at the same corner, and the top surface of the short crossbeams is in close contact with the bottom surface of the foundation support structure. Four long horizontal beams are set along the four sides of the historical building. The two ends of the long horizontal beams are respectively anchored to the short horizontal beams at the adjacent corners. The four long horizontal beams and the four short horizontal beams together form a closed frame-type support structure. Several temporary support units, each temporary support unit including temporary piles, auxiliary support components and cable beams; the auxiliary support components are cast-in-place concrete ground beams, one end of which extends to the bottom of the foundation support body and supports the foundation support body upwards, and the other end extends away from the historical building. The temporary piles are set on the outside of the historical building, below the auxiliary support components and supporting the auxiliary support components; one end of the cable-stayed beam is connected to the temporary piles, and the other end is connected to the end of the auxiliary support components away from the historical building; the end of the auxiliary support components away from the historical building is provided with a first outward-extending steel reinforcement mesh, and the two sides of the auxiliary support components located below the historical building are respectively provided with a second outward-extending steel reinforcement mesh, and the second steel reinforcement mesh is anchored in the long crossbeam; An outer reinforcement layer is provided at the end of the auxiliary support component away from the historical building. The outer reinforcement layer covers the first steel reinforcement mesh, and the first steel reinforcement mesh is anchored inside the outer reinforcement layer. Fill the voids in the base inside the frame-type foundation structure with concrete.
9. The historical building foundation settlement treatment underpinning structure according to claim 8, characterized in that, A flexible buffer layer is laid between the top surface of the short crossbeam and the bottom surface of the foundation support; the main reinforcement bars at both ends of the long crossbeam are embedded and anchored inside the short crossbeam, and the stirrups at the anchoring ends are densely arranged.
10. The historical building foundation settlement treatment underpinning structure according to claim 8, characterized in that, A grouting reinforcement layer is provided below the filling concrete, and the grouting reinforcement layer is a cement-water glass dual-liquid grout solidification body; the interface between the filling concrete and the long crossbeam is a roughened interface.