A prestressed stabilizing system for a Tibetan stone ancient tower and a construction method thereof

Abstract

The application discloses a prestress stabilizing system for a Tibetan-Qiang stone ancient tower and a construction method thereof, which comprises a plurality of ring prestress cable systems arranged around the outer wall of the tower, a vertical cable system arranged along each internal corner, and an inner ring steel beam arranged correspondingly in the tower and connected with the outer cable through a through rod. The upper end of the vertical cable system is hinged to a ring-shaped steel reinforced concrete beam embedded in the top, and the lower end is anchored to the foundation. During construction, the total constraint force and related design parameters are determined based on survey and numerical simulation, then the inner ring beam and the ring cable are alternately installed from bottom to top, the vertical cable is guided into position, and finally the vertical cable is synchronously and stepwise tensioned to activate the whole system, forming a main prestress constraint of "outer hoop and inner top". The whole system can be driven by tensioning the vertical cable, the force flow is clear, the regulation and control are convenient, the intervention to the cultural relic body is minimal and completely reversible, and the overall stability and disaster resistance of the tower are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of ancient building reinforcement, and specifically relates to a prestressed stabilization system for Tibetan and Qiang stone watchtowers and its construction method. Background Technology

[0002] The ancient Tibetan-Qiang stone watchtowers are constructed using local stones and loess. Each watchtower tapers upwards into a cone shape, with a double-layered, corbelled roof and crenellations. The walls are built of stacked stone slabs, bonded with yellow mud, thicker at the bottom and thinner at the top. The floors are supported by wooden beams and planks, with internal single-log ladders. The top floor is sealed with loess. The watchtowers are unique in craftsmanship and exquisite in construction. Having withstood several major earthquakes, they still stand, demonstrating the wisdom of ancient artisans. Besides their military function, the watchtowers are perfectly formed, incorporating the builders' aesthetic concepts and superb skills. Connected to residential buildings, the spatial layers are rich and varied, providing valuable material evidence for the study of Tibetan architecture and village layout. These Tibetan-Qiang stone watchtowers combine practicality and artistry, possessing high scientific research value. Located at the intersection of Qiang, Han, and Tibetan cultures, the watchtower is an essential place to study this unique ancient high-rise building. It is also a representative work that needs to be focused on in the study of the evolution of Tibetan style under the mutual influence of various cultures.

[0003] The construction methods and techniques of the ancient Tibetan and Qiang stone watchtowers differ from modern brick and stone structures. The mortar used in their construction is yellow mud, and after hundreds of years of wind and rain erosion and geological disasters, the bonding strength between the stones has deteriorated. The structure now relies primarily on the friction between the stones to provide structural resistance, a fundamentally different load-bearing mechanism from modern brick and stone buildings. Under the loads from daily environmental risks (wind, rain, sunlight, etc.), the tilt of the watchtowers increases annually, necessitating early reinforcement and stabilization measures to control the risk of instability while simultaneously meeting the requirements for preserving their historical and cultural value and ensuring safety and stability.

[0004] Currently, the safety and stability control of ancient stone buildings in my country mainly follows the concepts and reinforcement methods of modern engineering structures to combat risks. While this enhances the safety and stability of ancient stone buildings under normal use loads and minor earthquakes, it limits their inherent energy dissipation capacity during abnormal natural disasters such as major earthquakes. Recent earthquakes have consistently shown cases where ancient stone buildings suffered increased damage after being repaired. Furthermore, the repair, reinforcement, and maintenance of ancient stone buildings should strive to preserve their original appearance to ensure the authenticity of historical information. However, current reinforcement measures all require embedding into the building structure itself, making it difficult to achieve the principle of minimal intervention in the cultural relic and failing to guarantee its safety. There is an urgent need to develop safety and stability enhancement measures and equipment adapted to the performance characteristics and load-bearing mechanisms of Tibetan and Qiang ancient stone watchtowers to meet the needs of both historical preservation and safety and stability.

[0005] In other words, the existing technical problem is that the ancient Tibetan and Qiang stone watchtowers, constructed with stones and mortar, have experienced degradation of mortar bonding strength over hundreds of years, relying mainly on friction for stability. This increases the risk of tilting under modern wind and earthquake loads. Existing reinforcement techniques are mostly passive protection methods, requiring embedding into the artifact itself, involving significant and irreversible intervention, which fails to meet the principles of "minimal intervention" and "reversibility" in cultural relic protection. There is an urgent need to develop a reinforcement method that can effectively improve stability while maximizing the preservation of the original appearance of the artifact. Summary of the Invention

[0006] This invention provides a construction method to improve the stability of ancient Tibetan and Qiang stone watchtowers. This method addresses the issue that these watchtowers, constructed with stones and mortar, have experienced degradation of mortar joint adhesion over centuries, relying primarily on friction for stability. This increases the risk of tilting under modern wind and earthquake loads. Existing reinforcement techniques are mostly passive protection methods, requiring embedding into the artifact itself, resulting in significant and irreversible intervention, which fails to meet the technical requirements of "minimal intervention" and "reversibility" in cultural relic protection.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a prestressed stabilization system for ancient Tibetan and Qiang stone watchtowers, comprising, The circumferential prestressed cable system, which serves as a component for the conversion and distribution of constraint forces, includes multiple circumferential cables set at different heights around the outer wall of the watchtower. Each circumferential cable is connected to all vertical cables at the nodes. The vertical prestressed cable system, which serves as the active constraint force source and core force transmission carrier, includes multiple high-strength vertical cables installed along the entire height of each of the inner corners of the outer side of the watchtower. The inner ring steel beam and radial tie system, which serve as the final rigid support interface and the connection medium between the internal and external systems, include multiple inner ring steel beams set inside the watchtower at the corresponding circumferential cable elevation, as well as through-wire tie rods that penetrate the wall and connect the circumferential prestressed cable system with the inner ring steel beam. The upper end of the vertical prestressed cable system is connected to the ring-shaped steel-reinforced concrete beam embedded in the top of the watchtower via an adjustable hinge node, and the lower end is anchored to the foundation. The vertical prestressed cable system and the circumferential prestressed cable system are connected at the inner corners of the watchtower. The circumferential prestressed cable system, the inner ring steel beam, and the radial tension system are connected. By applying design tension to the vertical prestressed cable system, this tension is transmitted through the nodes and drives the circumferential prestressed cable system, the inner ring steel beam, and the radial tension system to work together, thereby forming an active and adjustable prestressed constraint on the watchtower masonry.

[0008] Preferably, the circumferential prestressed cable system includes circumferential cables, first cable clamps, first rubber pads, and angle steel. The two sides of the angle steel are respectively attached to the two sides of the outer external corner of the watchtower. The first rubber pad is set between the angle steel and the outer wall of the watchtower. The first cable clamp is L-shaped and is respectively attached to the outer sides of the angle steel. Circumferential cables are respectively threaded through the two sides of the first cable clamp. The circumferential cables are connected to the vertical prestressed cable system at each inner corner of the watchtower. The end of the circumferential cable is press-fitted with a threaded rod. The threaded rod passes through the first cable clamp and is tensioned and fixed by double nuts on the outside of the first cable clamp. The preload of the circumferential cable is transmitted to the vertical angle steel through the cable clamp node and is evenly diffused to the outer wall of the watchtower through the angle steel and the elastic pad. The circumferential cable forms a circumferential cable system around the corner of the watchtower, and the two ends are respectively connected end to end at the corner of the watchtower through the first cable clamp.

[0009] Preferably, the vertical prestressed cable system comprises vertical cables, lower anchors, upper anchors, and a second cable clamp. The vertical cables are arranged at the outer corner of the watchtower. A groove is cut into the top of the watchtower and a ring-shaped steel-reinforced concrete beam is pre-embedded. An upper ear plate is installed on the outer side of the watchtower, inserted into the groove, and welded to the steel beam of the ring-shaped steel-reinforced concrete beam. The top of the vertical cables is connected to the upper ear plate by a pin through the upper anchor. A concrete foundation is poured on the foundation outside the watchtower and a concrete foundation ring beam is pre-embedded. A lower ear plate is fixed on the concrete foundation ring beam. The bottom of the vertical cables is fixed to the lower ear plate through the lower anchor. Both the lower and upper anchors are double-ear adjustable anchors to form an adjustable hinge node, forming a hinge connection that can release the end moment. The adjustable anchor is equipped with a long screw and a locking nut for applying and locking the tension of the vertical cables.

[0010] Preferably, the inner ring steel beam and radial tension system include a steel ring beam, a through-rod, and a second rubber pad. The steel ring beam is located on the inner side of the watchtower corresponding to the circumferential cable. The outer side of the steel ring beam is in close contact with the inner wall of the watchtower, and the gap between the steel ring beam and the inner wall of the watchtower is filled with fine stone concrete. At the same time, an isolation material is placed between the inner wall of the watchtower and the fine stone concrete to prevent contamination of the interior of the watchtower. The second cable clamp includes an inner clamp plate and an outer clamp plate. The surfaces of the inner and outer clamp plates that are in contact with each other have grooves corresponding to the vertical cable and smaller than the diameter of the vertical cable. The inner clamp plate also has a through hole for the circumferential cable to pass through. The circumferential cable passes through the inner clamp plate, and the vertical cable is clamped and fixed by the inner and outer clamp plates. The through-rod passes through the steel ring beam, the inner clamp plate, and the outer clamp plate and is fixed by double nuts on the inner side of the steel ring beam and bolts on the outer side of the outer clamp plate. The second rubber pad is placed between the inner clamp plate and the watchtower.

[0011] Preferably, the diameter of the circumferential and vertical cables is 12mm-30mm, and the material is high-strength steel cable with zinc-5% aluminum-rare earth alloy coating.

[0012] Preferably, the first and second rubber pads are made of natural rubber with a thickness between 20mm and 30mm, and the angle steel is made of steel with a yield strength of not less than 355MPa and a thickness between 8mm and 12mm.

[0013] Preferably, the circumferential prestressed cable system, the vertical prestressed cable system, and the inner ring steel beam and radial tie system located on the outside of the watchtower are coated with a color that matches the style of the watchtower, so as not to affect the external appearance and aesthetics of the watchtower.

[0014] Preferably, two vertical cables are evenly arranged at the inside corner of the outer wall of the same watchtower.

[0015] A construction method for a prestressed stabilization system for ancient Tibetan and Qiang stone watchtowers includes the following steps: S1: System Design Calculation and Component Preparation Steps: Based on the survey data of the target watchtower, the total constraint force F required by the system is determined through numerical simulation using a finite element model. total Based on this, the design parameters and specifications of the circumferential prestressed cable system, the vertical prestressed cable system, the inner ring steel beam, and the radial tension system in the prestressed stabilization system are calculated and determined. S2: Anchoring foundation construction steps: make partial repairs on the top of the watchtower and pre-embed the ring-shaped steel-reinforced concrete beam, and pre-set the lower anchoring points of the vertical prestressed cable system in the foundation of the watchtower; S3: Step-by-step installation from bottom to top: Starting from the bottom of the watchtower, first install the bottom inner ring steel beam and circumferential cable, and initially connect the two with through-rods; then, in order from bottom to top, alternately install the upper inner ring steel beam, circumferential cable and its connecting components; during the installation process, guide the vertical prestressed cable into position along the inside corner of the watchtower, and connect it to the circumferential cable at the node with cable clamps, but do not apply the final design tension to the vertical cable at this time; S4: Overall synchronous tensioning and locking steps: After all system components are installed in place, the vertical prestressed cables are synchronously tensioned in stages to make their tension reach the design value, thereby driving the entire system to work together and forming prestressed constraints on the watchtower masonry. Then, the anchors at the ends of the vertical cables are locked. S5: Long-term monitoring and maintenance adjustment steps: Set long-term monitoring points at the anchorages of the vertical prestressed cable system, monitor the cable force regularly, and adjust the cable force according to the monitoring data to maintain system efficiency.

[0016] Preferably, in step S1, according to F total Determine the design preload F of a single circumferential cable. pre According to formula F break ≥γ*F preA safety factor γ of not less than 2.5 is selected to determine and choose the specifications for the circumferential and vertical cables, where F break The nominal breaking force of the cable; based on the local bearing pressure calculation formula σ c =F pre / A con ≤ψ*f c Design the dimensions of the angle steel and rubber pad in the corner joint, where σ c For local compressive stress on the stone surface, A con f is the contact area between the angle steel / rubber pad and the stone. c Here, ψ represents the standard value of the stone's compressive strength, and ψ is the high-strength reduction factor for the cultural relic itself, ranging from 0.3 to 0.5; based on the bending stiffness requirement E of the inner ring beam... _s *I _s ≥η*E _m *I _m Design the cross-section of the inner ring steel beam, where E _s *I _s E represents the bending stiffness of the steel ring beam section. _m *I _m The equivalent bending stiffness of the reinforced section of the watchtower wall is η, which is a stiffness multiple not less than 5; the strength verification formula for the through-bar is σ=F. pre / A≤f The design specifies the tie rod specifications, where σ is the calculated stress of the tie rod, A is the effective cross-sectional area at the thread of the tie rod, and f is the design value of the tensile strength of the tie rod material; based on the above design results, prepare all system components.

[0017] The beneficial effects of this invention are reflected in the following aspects from a mechanical design perspective: 1. Concentrated force source, unified control: Only a limited number of vertical cables need to be tensioned to simultaneously activate the constraint network across the entire height, simplifying construction and ensuring precise control. 2. Clear force flow, significantly increased efficiency: A unidirectional and efficient force flow path is established, from "vertical cable (tension) → node (transmission) → circumferential cable (tension) → tie rod (tension) → inner ring beam (compression / bending) → wall (compression)," with a clear concept and rigorous mechanical logic. 3. Convenient control and simple maintenance: The tension of the vertical cables is the "master switch" and "barometer" of the system's state. By monitoring and adjusting the cable force, the overall reinforcement effect can be easily controlled, enabling long-term performance maintenance. 4. Minimal intervention, fully reversible: All key components are detachable metal parts, causing only minimal perforation damage to the artifact itself, fully complying with the principle of reversibility in artifact preservation. 5. High adaptability: By adjusting the shape of the inner ring beam and the node structure, this system can flexibly adapt to watchtowers with different planar forms such as four corners, hexagons, and octagons, as well as different heights and defects.

[0018] In terms of construction effectiveness: 1. By actively and continuously compressing the loose masonry with prestress, the integrity of the masonry is fundamentally restored and maintained, effectively inhibiting crack development and significantly improving shear and overturning resistance. 2. All major reinforcing components (steel cables, steel beams, tie rods) are detachable metal parts, causing only minimal and necessary perforations to the artifact itself, preserving its original appearance to the greatest extent. The prestress level can be adjusted based on long-term monitoring data, and the system itself is completely reversible. 3. The "flexible exterior, rigid interior" system forms a self-balancing force system. The external flexible cable net adapts to irregular shapes and provides uniform constraint, while the internal rigid beam provides stable support and resists internal buckling, demonstrating clear mechanical concepts and high material efficiency. 4. The system components can flexibly adapt to watchtowers of different sizes and planar shapes (square, hexagonal, octagonal), and the inner ring beam can be segmentally fitted to irregular inner walls, exhibiting strong versatility. 5. The design methodology creatively incorporates a high strength reduction factor (typically 0.3-0.5) and a higher component safety factor (≥2.5) for the artifact itself, ensuring that the reinforcement force itself will not damage the fragile historical masonry under any circumstances. Rubber pads at the corners further cushion and evenly distribute pressure.

[0019] Other features and advantages of the 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 main objects and other advantages of the invention may be realized and obtained by means of the embodiments particularly pointed out in the description. Attached Figure Description

[0020] Figure 1 This is a structural elevation diagram of an embodiment of the present invention; Figure 2 This is a top view of an embodiment of the present invention; Figure 3 This is an installation diagram of the circumferential cable and the first cable clamp according to an embodiment of the present invention; Figure 4 This is a side view of the first cable clamp according to an embodiment of the present invention; Figure 5 This is an installation diagram of the top of the vertical cable according to an embodiment of the present invention; Figure 6 This is an installation diagram of the bottom of the vertical cable according to an embodiment of the present invention; Figure 7 This is a diagram showing the junction of the vertical and circumferential cables in an embodiment of the present invention. Figure 8 This is a schematic diagram of the inner ring steel beam and radial tension system on the inner side of the watchtower according to an embodiment of the present invention; Figure 9 This is a schematic diagram illustrating the overall effect of an embodiment of the present invention; Figure 10 This is an enlarged view of the effect of an embodiment of the present invention.

[0021] Reference numerals: 1. Circumferential prestressed cable system; 11. Circumferential cable; 12. First cable clamp; 13. First rubber pad; 14. Angle steel; 2. Vertical prestressed cable system; 21. Vertical cable; 22. Lower anchorage; 23. Upper anchorage; 24. Second cable clamp; 241. Inner clamp plate; 242. Outer clamp plate; 25. Circumferential steel-reinforced concrete beam; 26. Upper ear plate; 27. Concrete foundation ring beam; 28. Lower ear plate; 3. Inner ring steel beam and radial tension system; 31. Steel ring beam; 32. Through-rod; 33. Second rubber pad. Detailed Implementation

[0022] The technical solutions of the present invention will be described in detail below through embodiments. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solutions of the present invention, and should not be construed as limiting the technical solutions of the present invention.

[0023] Combination Figure 1-10 A prestressed stabilization system for ancient Tibetan and Qiang stone watchtowers, comprising: The circumferential prestressed cable system 1, which serves as a component for the conversion and distribution of constraint forces, includes multiple circumferential cables 11 arranged at different heights around the outer wall of the watchtower. Each circumferential cable 11 is connected to all vertical cables 21 at a node. The vertical prestressed cable system 2, which serves as the active constraint force source and core force transmission carrier, includes multiple high-strength vertical cables 21 installed along the entire height of each inner corner of the outer side of the watchtower. The inner ring steel beam and radial tie system 3, which serve as the final rigid support interface and the connection medium between the internal and external systems, include multiple inner ring steel beams set inside the watchtower at the corresponding elevation of the circumferential cable 11, as well as through-rods 32 that penetrate the wall and connect the circumferential prestressed cable system 1 and the inner ring steel beam. The upper end of the vertical prestressed cable system 2 is connected to the annular steel-reinforced concrete beam 25 embedded in the top of the watchtower via an adjustable hinge node, and the lower end is anchored to the foundation. The vertical prestressed cable system 2 and the circumferential prestressed cable system 1 are connected at each of the inner corners of the watchtower. The circumferential prestressed cable system 1, the inner ring steel beam, and the radial tension system 3 are connected. By applying the design tension to the vertical prestressed cable system 2, the tension is transmitted through the nodes and drives the circumferential prestressed cable system 1, the inner ring steel beam, and the radial tension system 3 to work together, thereby forming an active and adjustable prestressed constraint on the watchtower masonry.

[0024] The circumferential prestressed cable system 1 includes circumferential cables 11, first cable clamps 12, first rubber pads 13, and angle steel 14. The two sides of the angle steel 14 are respectively attached to the two sides of the outer external corner of the watchtower. The first rubber pad 13 is installed between the angle steel 14 and the outer wall of the watchtower. The first cable clamp 12 is L-shaped and is attached to the outer sides of the angle steel 14. The circumferential cables 11 are threaded through the two sides of the first cable clamp 12, and are staggered in height. The circumferential cables 11 are connected to the outer internal corners of the watchtower. The vertical prestressed cable system 2 is connected. The end of the circumferential cable 11 is crimped with a threaded rod. The threaded rod passes through the first cable clamp 12 and is tensioned and fixed by the double nuts on the outside of the first cable clamp 12. The preload of the circumferential cable 11 is transmitted to the vertical angle steel 14 through the cable clamp node, and is evenly diffused to the outer wall of the watchtower through the angle steel 14 and the elastic pad. The circumferential cable 11 forms a circumferential cable system around the corner of the watchtower. The two ends are connected end to end at the corner of the watchtower by the first cable clamp 12.

[0025] The vertical prestressed cable system 2 comprises a vertical cable 21, a lower anchor 22, an upper anchor 23, and a second cable clamp 24. The vertical cable 21 is arranged at the outer corner of the watchtower. A groove is cut into the top of the watchtower and a ring-shaped steel-reinforced concrete beam 25 is pre-embedded. An upper ear plate 26 is installed on the outer side of the watchtower, inserted into the groove, and welded to the steel beam of the ring-shaped steel-reinforced concrete beam 25. The top of the vertical cable 21 is connected to the upper ear plate 26 by a pin through the upper anchor 23. A concrete foundation is poured on the side of the foundation and a concrete foundation ring beam 27 is pre-embedded. A lower ear plate 28 is fixed on the concrete foundation ring beam 27. The bottom end of the vertical cable 21 is fixedly connected to the lower ear plate 28 through the lower anchor 22. The lower anchor 22 and the upper anchor 23 are both double-ear adjustable anchors to form an adjustable hinge node, forming a hinge connection that can release the end bending moment. The adjustable anchor is equipped with a long screw and a locking nut to apply and lock the tension of the vertical cable 21.

[0026] The inner ring steel beam and radial tension system 3 includes a steel ring beam 31, a through-rod 32, and a second rubber pad 33. The steel ring beam 31 is installed on the inner side of the watchtower corresponding to the circumferential cable 11. The outer side of the steel ring beam 31 is tightly attached to the inner wall of the watchtower, and the gap between the steel ring beam 31 and the inner wall of the watchtower is filled with fine stone concrete. At the same time, an isolation material is placed between the inner wall of the watchtower and the fine stone concrete to prevent contamination of the interior of the watchtower. The second cable clamp 24 includes an inner clamp plate 241 and an outer clamp plate 242. The surfaces on which the inner clamp plate 241 and the outer clamp plate 242 are attached are divided into... The inner clamping plate 241 has a groove corresponding to the vertical cable 21 and smaller than the diameter of the vertical cable 21. The inner clamping plate 241 also has a through hole for the circumferential cable 11 to pass through. The circumferential cable 11 passes through the inner clamping plate 241. The vertical cable 21 is clamped and fixed by the inner clamping plate 241 and the outer clamping plate 242. The through-rod 32 passes through the steel ring beam 31, the inner clamping plate 241 and the outer clamping plate 242 and is fixed by the double nuts on the inner side of the steel ring beam 31 and the bolts on the outer side of the outer clamping plate 242. The second rubber pad 33 is placed between the inner clamping plate 241 and the watchtower.

[0027] The diameter of the circumferential cable 11 and the vertical cable 21 is 12mm-30mm, and the material is high-strength steel cable with zinc-5% aluminum-rare earth alloy coating.

[0028] The first rubber pad 13 and the second rubber pad 33 are made of natural rubber with a thickness between 20mm and 30mm. The angle steel 14 is made of steel with a yield strength of not less than 355MPa and a thickness between 8mm and 12mm.

[0029] The circumferential prestressed cable system 1, the vertical prestressed cable system 2, and the inner ring steel beam and radial tension system 3, located on the outside of the watchtower, are coated with a color that matches the style of the watchtower, so as not to affect the external appearance and aesthetics of the watchtower.

[0030] Two vertical cables 21 are evenly installed at the inner corner of the same watchtower's outer wall, and two circumferential cables 11 are installed in the vertical direction, forming a couple to resist torsion and out-of-plane bending. The inner corner of the watchtower is a weak line and a critical stress point in its facade. The constraint provided by a single cable can be simplified to a concentrated force acting on the corner. Setting two parallel cables with a certain spacing is equivalent to applying a couple at the corner, which can more effectively resist the shear force in the wall plane and possible local torsion or out-of-plane bending, thus improving the stress state of the corner from "line constraint" to "surface constraint," making it more stable. More precise tension control and correction are achieved: For a tilted watchtower, a corrective moment can be formed by distributing higher tension to the cable on the side with severe deformation. Each corner has two independently adjustable cables, providing a more flexible means for such fine adjustment. Redundancy is achieved: In extremely important cultural relic reinforcement projects, safety is paramount. Setting two cables on the same critical force transmission path (inner corner) constitutes a redundant system. Even if one cable fails due to extreme circumstances (such as being hit by a falling object or rare corrosion), the other cable can still provide necessary restraint to prevent the system from collapsing instantly, buying time for maintenance and greatly improving the safety margin and robustness of the entire reinforcement system. During construction, fine-tuning the tension of the two cables at the same corner can correct for more subtle uneven deformation or installation deviations. It facilitates monitoring and diagnosis: the cable forces of the two cables can serve as a reference for each other. In long-term monitoring (such as step S5), if a significant difference in the tension values ​​of the two cables at the same corner occurs, it can serve as an early warning signal, indicating possible loosening of nodes, local structural changes, or other anomalies, facilitating timely investigation. Furthermore, it can disperse stress and protect the cultural relic: the force of the circumferential cable 11 is transmitted to the wall through the angle steel 14 and rubber pads. When the tension of the vertical cable 21 is transmitted to the circumferential cable 11 through the cable clamp node, the tension of the two vertical cables 21 is shared by two nodes, thereby reducing the local compressive stress on the ancient stone from a single angle steel 14-rubber pad node. This aligns with the document's emphasis on rigorous local pressure verification and embodies the principle of "minimal intervention" in mechanical design.

[0031] A construction method for a prestressed stabilization system for ancient Tibetan and Qiang stone watchtowers includes the following steps: S1: System Design Calculation and Component Preparation Steps: Based on the survey data of the target watchtower, the total constraint force F required by the system is determined through numerical simulation using a finite element model. total Based on this, the design parameters and specifications of the circumferential prestressed cable system, the vertical prestressed cable system, the inner ring steel beam, and the radial tension system in the prestressed stabilization system are calculated and determined. S2: Anchoring foundation construction steps: make partial repairs on the top of the watchtower and pre-embed the ring-shaped steel-reinforced concrete beam, and pre-set the lower anchoring points of the vertical prestressed cable system in the foundation of the watchtower; S3: Step-by-step installation from bottom to top: Starting from the bottom of the watchtower, first install the bottom inner ring steel beam and circumferential cable, and initially connect the two with through-rods; then, in order from bottom to top, alternately install the upper inner ring steel beam, circumferential cable and its connecting components; during the installation process, guide the vertical prestressed cable into position along the inside corner of the watchtower, and connect it to the circumferential cable at the node with cable clamps, but do not apply the final design tension to the vertical cable at this time; S4: Overall synchronous tensioning and locking steps: After all system components are installed in place, the vertical prestressed cables are synchronously tensioned in stages to make their tension reach the design value, thereby driving the entire system to work together and forming prestressed constraints on the watchtower masonry. Then, the anchors at the ends of the vertical cables are locked. S5: Long-term monitoring and maintenance adjustment steps: Set long-term monitoring points at the anchorages of the vertical prestressed cable system, monitor the cable force regularly, and adjust the cable force according to the monitoring data to maintain system efficiency.

[0032] Preferably, in step S1, according to F total Determine the design preload F of a single circumferential cable. pre According to formula F break ≥γ*F pre A safety factor γ of not less than 2.5 is selected to determine and choose the specifications for the circumferential and vertical cables, where F break The nominal breaking force of the cable; based on the local bearing pressure calculation formula σ c =F pre / A con ≤ψ*f c Design the dimensions of the angle steel and rubber pad in the corner joint, where σ c For local compressive stress on the stone surface, A con f is the contact area between the angle steel / rubber pad and the stone. c Here, ψ represents the standard value of the stone's compressive strength, and ψ is the high-strength reduction factor for the cultural relic itself, ranging from 0.3 to 0.5; based on the bending stiffness requirement E of the inner ring beam... _s *I _s ≥η*E _m *I _m Design the cross-section of the inner ring steel beam, where E _s *I _s E represents the bending stiffness of the steel ring beam section. _m *I _m The equivalent bending stiffness of the reinforced section of the watchtower wall is η, which is a stiffness multiple not less than 5; the strength verification formula for the through-bar is σ=F. pre / A≤f The design specifies the tie rod specifications, where σ is the calculated stress of the tie rod, A is the effective cross-sectional area at the thread of the tie rod, and f is the design value of the tensile strength of the tie rod material; based on the above design results, prepare all system components.

[0033] The invention will be further described in detail using an example of a 40-meter-high octagonal stone watchtower. Example: A giant octagonal stone watchtower, 40 meters high, approximately 8 meters wide at each side, with walls approximately 1.2 meters thick at the base and 0.8 meters thick at the top, exhibiting severe weathering and penetrating cracks at the corners. Total prestress estimation F total Based on the total constraint force required by the system inverted using the finite element model, numerical simulation is performed using the finite element model, and the total prestress F is determined according to the goal of improving stability performance. total .

[0034] Step 1: The 40-meter height of the watchtower makes it susceptible to significant wind and seismic loads, which become the dominant lateral forces. Structural calculations, considering the combined effects of wind and seismic forces, show that the enormous overturning moment generated in the upper part of the watchtower is the primary threat. Numerical simulations indicate that to improve the overall structural stability of the watchtower by 30%, the reinforcement system must provide a total vertical restraint force F of no less than 720 kN. total This forms an effective bending continuum across the entire height. To effectively transmit and resist overturning moments, the single-track ring cable is designed with a preload F. pre = 720kN / 4 = 180kN. Considering the complex dynamic response of ultra-high-rise structures, a higher safety factor γ = 2.7 is adopted. Required single-cable breaking force F break ≥2.7 * 180 kN = 486 kN. Select a sealed steel wire rope with a diameter of 22 mm. For example... Figure 1 , Figure 2 In this embodiment, a stability enhancement measure for a Tibetan-Qiang stone watchtower involves installing five circumferential cables every 4 meters below the top of the watchtower, with two cables per cable, each 22mm in diameter. Eight vertical prestressed cables, two cables per cable, are arranged along the inner corners of the watchtower. The vertical and circumferential cables are connected by cable clamps. An inner ring steel beam is installed inside the watchtower corresponding to the circumferential cables, and the inner ring beam is connected to the external horizontal and vertical cables by tie bolts. During the renovation of the top of the watchtower, a ring-shaped steel-reinforced concrete beam is pre-embedded, with cantilevered end plates connecting to the vertical cables. The lower part of the vertical cables is connected to the bottom concrete foundation, forming a strong and resilient spatial lattice-type cylindrical tensioned net.

[0035] Step 2: Following preliminary surveys, the strength f of the stone material at the corner of the watchtower was determined. c The pressure was measured at 6 MPa. The corner nodes of the octagonal plane (135° interior angle) require special design. For example... Figure 3 Angle steel 14 uses a hot-rolled, 135° concave shaped steel pad to perfectly fit the corner and increase the bearing area. The contact area A of the shaped steel pad is... con=0.15m² and 30mm thick rubber pad 13. Local compressive stress σ _c =300kN / 0.15m² = 2.0MPa. Using a highly conservative reduction factor ψ = 0.33, the allowable stress is 0.33 * 6 = 1.98MPa. The rubber pad will be replaced with a more elastic neoprene rubber to enhance stress diffusion, ultimately satisfying σ. _c ≤ψ*f _c Requirements.

[0036] Step 3: To resist the in-plane shear force generated by the enormous lateral force, the inner ring beam 31 is made of 250*250*16 Q355B square steel tubing. Its bending stiffness is verified: E _s *I _s ≈4.2*10^5 kN·m², which is much greater than the equivalent stiffness of the reinforced wall (E m *I m More than 5 times stronger than the previous type, meeting the requirements for rigid force transmission. The through-rod 32 has been upgraded to an M36 850-grade high-strength screw, whose tensile design value is sufficient to safely transmit a tensile force of 300kN.

[0037] Step 4: Install the bottommost circumferential cable and the bottom inner ring beam, and initially tension them to establish foundation constraints. Then, install the upper ring cables, inner ring beam, and connecting rods alternately from bottom to top. The vertical cables serve as stabilizing cables throughout the process, gradually tightening as construction progresses. After all cables are in place, perform overall tensioning. Four jacks are used simultaneously at the four symmetrical corners. Tensioning is performed in three stages: 30%, 60%, and 100% of the design preload. Each stage is held for 10 minutes, and sensors monitor cable tension and strain at the corners of the watchtower to ensure uniform stress. After tensioning to 100%, all adjustable anchorages are locked and sealed for corrosion protection.

[0038] Step 5: Install long-term stress monitoring points at the adjusting anchors of the vertical cables. Take readings periodically. If the cable tension drops by more than 10% of the design value, the system can be easily tensioned again by tightening the adjusting anchors to restore system performance and achieve sustainable protection.

[0039] This embodiment demonstrates the scientific validity, advanced technology, and operability of a reinforcement system using vertical cables as the core force source and carrier for solving the stability problems of extremely tall and complex ancient watchtowers. The system provided by this invention can safely and effectively solve the extremely complex reinforcement problem of a 40-meter-high giant octagonal watchtower, making it particularly suitable for the technical advantages of this invention.

[0040] Furthermore, this method can be applied to watchtowers that have already tilted or twisted significantly due to foundation problems. Simply applying uniform and symmetrical prestress may not correct the deformation or could even exacerbate it. Through structural analysis, the severely deformed side and the stable side of the watchtower are identified. After calculating the total constraint force Ftotal, a higher design preload is allocated to the circumferential cables on the severely deformed side, forming a restoring moment to correct the deformation. Independent adjustment of the vertical cables: All 21 vertical cables utilize precision adjusting anchors with digital displays and mechanical self-locking functions. During the long-term monitoring phase after tensioning, the force of one or several vertical cables can be fine-tuned based on tilt monitoring data, achieving dynamic adjustment for correction.

[0041] Furthermore, for watchtowers with extremely limited internal space or inconvenient entrances for large components, smaller cross-section high-strength steel can be used, and the structure can be designed with shorter segments. All connecting plates are pre-welded, requiring only bolt tightening on site. The construction sequence is adjusted as follows: first, install the inner ring beam segments; then, inject highly fluid, micro-expansion grout into the gap between the beam and the wall; finally, after the grout has reached its strength, install and tension the cable system from the outside. This sequence avoids displacement of large inner beams due to the influence of the cables before they are fixed.

[0042] Furthermore, for particularly important national treasure-level watchtowers requiring preventative protection and long-term health monitoring, fiber optic strain sensors can be installed on the circumferential and vertical cables at key locations, embedded within the cable body or attached to the surface; micro-compression stress sensors can be installed between the angle steel and the wall; and high-precision inclinometers can be installed on the top and foundation of the watchtower. Real-time analysis of cable force, wall pressure, and structural tilt trends is possible. Thresholds are set, and when data anomalies occur (such as a sudden drop in cable force exceeding 10%, potentially indicating loosening of the cable clamp or localized damage), an early warning message is automatically sent to management personnel.

[0043] From a mechanical design perspective: 1. Concentrated force source, unified control: Tensioning only a limited number of vertical cables simultaneously activates the constraint network across the entire height, simplifying construction and ensuring precise control. 2. Clear force flow, significantly increased efficiency: A unidirectional, highly efficient force flow path is established: "Vertical cable (tension) → Node (transmission) → Circumferential cable (tension) → Tie rod (tension) → Inner ring beam (compression / bending) → Wall (compression)," with a clear concept and rigorous mechanical logic. 3. Convenient control, simple maintenance: The tension of the vertical cables serves as the "master switch" and "barometer" of the system's state. By monitoring and adjusting the cable force, the overall reinforcement effect can be easily controlled, enabling long-term performance maintenance. 4. Minimal intervention, fully reversible: All key components are detachable metal parts, causing only minimal perforation damage to the artifact itself, fully complying with the reversibility principle of cultural relic protection. 5. High adaptability: By adjusting the shape of the inner ring beam and the node structure, this system can flexibly adapt to watchtowers with different planar forms such as four corners, hexagons, and octagons, as well as different heights and defects.

[0044] In terms of construction effectiveness: 1. By actively and continuously compressing the loose masonry with prestress, the integrity of the masonry is fundamentally restored and maintained, effectively inhibiting crack development and significantly improving shear and overturning resistance. 2. All major reinforcing components (steel cables, steel beams, tie rods) are detachable metal parts, causing only minimal and necessary perforations to the artifact itself, preserving its original appearance to the greatest extent. The prestress level can be adjusted based on long-term monitoring data, and the system itself is completely reversible. 3. The "flexible exterior, rigid interior" system forms a self-balancing force system. The external flexible cable net adapts to irregular shapes and provides uniform constraint, while the internal rigid beam provides stable support and resists internal buckling, demonstrating clear mechanical concepts and high material efficiency. 4. The system components can flexibly adapt to watchtowers of different sizes and planar shapes (square, hexagonal, octagonal), and the inner ring beam can be segmentally fitted to irregular inner walls, exhibiting strong versatility. 5. The design methodology creatively incorporates a high strength reduction factor (typically 0.3-0.5) and a higher component safety factor (≥2.5) for the artifact itself, ensuring that the reinforcement force itself will not damage the fragile historical masonry under any circumstances. Rubber pads at the corners further cushion and evenly distribute pressure.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A prestressed stabilization system for ancient stone watchtowers of the Tibetan and Qiang ethnic groups, characterized in that: include, The circumferential prestressed cable system (1), which serves as a component for the conversion and distribution of constraint forces, includes multiple circumferential cables (11) arranged at different heights around the outer wall of the watchtower. Each circumferential cable (11) is connected to all vertical cables (21) at a node. The vertical prestressed cable system (2), which serves as the active constraint force source and core force transmission carrier, includes multiple high-strength vertical cables (21) installed along the entire height of each inner corner of the outer side of the watchtower. The inner ring steel beam and radial tie system (3), which serve as the final rigid support interface and the connection medium between the internal and external systems, include multiple inner ring steel beams set inside the watchtower at the corresponding elevation of the circumferential cable (11) and through-rods (32) that penetrate the wall and connect the circumferential prestressed cable system (1) and the inner ring steel beam. The upper end of the vertical prestressed cable system (2) is connected to the ring-shaped steel-reinforced concrete beam (25) embedded in the top of the watchtower through an adjustable hinge node, and the lower end is anchored to the foundation. The vertical prestressed cable system (2) and the circumferential prestressed cable system (1) are connected at each of the inner corners of the watchtower. The circumferential prestressed cable system (1), the inner ring steel beam, and the radial tension system (3) are connected. By applying the design tension to the vertical prestressed cable system (2), the tension is transmitted through the node and drives the circumferential prestressed cable system (1), the inner ring steel beam, and the radial tension system (3) to work together, thereby forming an active and adjustable prestressed constraint on the watchtower masonry.

2. The prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 1, characterized in that: The circumferential prestressed cable system (1) includes circumferential cables (11), first cable clamps (12), first rubber pads (13), and angle steel (14). The two sides of the angle steel (14) are respectively attached to the two sides of the outer external corner of the watchtower. The first rubber pads (13) are set between the angle steel (14) and the outer wall of the watchtower. The first cable clamps (12) are L-shaped and are respectively attached to the outer sides of the angle steel (14). The circumferential cables (11) are respectively threaded through the two sides of the first cable clamps (12). The circumferential cables (11) are located at each inner corner of the outer side of the watchtower. Connected to the vertical prestressed cable system (2), the end of the circumferential cable (11) is press-fitted with a threaded rod. The threaded rod passes through the first cable clamp (12) and is tensioned and fixed by the double nuts on the outside of the first cable clamp (12). The preload of the circumferential cable (11) is transmitted to the vertical angle steel (14) through the cable clamp node, and is evenly diffused to the outer wall of the watchtower through the angle steel (14) and the elastic pad. The circumferential cable (11) forms a circumferential cable system around the corner of the watchtower, and the two ends are connected end to end at the corner of the watchtower through the first cable clamp (12).

3. A prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 2, characterized in that: The vertical prestressed cable system (2) comprises a vertical cable (21), a lower anchor (22), an upper anchor (23), and a second cable clamp (24). The vertical cable (21) is arranged at the inner corner of the outer side of the watchtower. The top of the watchtower is slotted and a ring-shaped steel-reinforced concrete beam (25) is pre-embedded. An upper ear plate (26) is installed on the outer side of the watchtower and inserted into the slot to be welded and fixed to the steel beam of the ring-shaped steel-reinforced concrete beam (25). The top of the vertical cable (21) is connected to the upper ear plate (26) by a pin through the upper anchor (23). A concrete foundation is poured on the outer side of the watchtower and a concrete foundation ring beam (27) is pre-embedded. A lower ear plate (28) is fixed on the concrete foundation ring beam (27). The bottom end of the vertical cable (21) is fixedly connected to the lower ear plate (28) through the lower anchor (22). The lower anchor (22) and the upper anchor (23) are both double-ear adjustable anchors to form an adjustable hinge node, forming a hinge connection that can release the end bending moment. The adjustable anchor is equipped with a long screw and a locking nut, which are used to apply and lock the tension of the vertical cable (21).

4. A prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 3, characterized in that: The inner ring steel beam and radial tension system (3) include a steel ring beam (31), a through-rod (32), and a second rubber pad (33). The steel ring beam (31) is set on the inner side of the watchtower corresponding to the circumferential cable (11). The outer side of the steel ring beam (31) is close to the inner wall of the watchtower, and the gap between the steel ring beam (31) and the inner wall of the watchtower is filled with fine stone concrete. The second cable clamp (24) includes an inner clamp plate (241) and an outer clamp plate (242). The surfaces of the inner clamp plate (241) and the outer clamp plate (242) that are in contact with each other have corresponding to the vertical cable (21) and smaller than the vertical cable. The groove is oriented towards the diameter of the cable (21). The inner clamping plate (241) also has a through hole for the circumferential cable (11) to pass through. The circumferential cable (11) passes through the inner clamping plate (241). The vertical cable (21) is clamped and fixed by the inner clamping plate (241) and the outer clamping plate (242). The through rod (32) passes through the steel ring beam (31), the inner clamping plate (241) and the outer clamping plate (242) and is fixed by the double nuts on the inner side of the steel ring beam (31) and the bolts on the outer side of the outer clamping plate (242). The second rubber pad (33) is placed between the inner clamping plate (241) and the watchtower.

5. A prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 4, characterized in that: The diameter of the circumferential cable (11) and the vertical cable (21) is 12mm-30mm, and the material is high-strength steel cable with zinc-5% aluminum-rare earth alloy coating.

6. A prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 5, characterized in that: The first rubber pad (13) and the second rubber pad (33) are made of natural rubber with a thickness of 20mm-30mm. The angle steel (14) is made of steel with a yield strength of not less than 355MPa and a thickness of 8mm-12mm.

7. A prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 6, characterized in that: The circumferential prestressed cable system (1), the vertical prestressed cable system (2), and the inner ring steel beam and radial tie system (3) located on the outside of the watchtower are coated with a color that matches the style of the watchtower, so as not to affect the external appearance and viewing of the watchtower.

8. A prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 7, characterized in that: Two vertical cables (21) are evenly arranged at the inside corner of the outer wall of the same watchtower.

9. A construction method for a prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to any one of claims 1-8, characterized in that: Includes the following steps, S1: System Design Calculation and Component Preparation Steps: Based on the survey data of the target watchtower, the total constraint force F required by the system is determined through numerical simulation using a finite element model. total Based on this, the design parameters and specifications of the circumferential prestressed cable system, the vertical prestressed cable system, the inner ring steel beam, and the radial tension system in the prestressed stabilization system are calculated and determined. S2: Anchoring foundation construction steps: make partial repairs on the top of the watchtower and pre-embed the ring-shaped steel-reinforced concrete beam, and pre-set the lower anchoring points of the vertical prestressed cable system in the foundation of the watchtower; S3: Step-by-step installation from bottom to top: Starting from the bottom of the watchtower, first install the bottom inner ring steel beam and circumferential cable, and initially connect the two with through-rods; then, in order from bottom to top, alternately install the upper inner ring steel beam, circumferential cable and its connecting components; during the installation process, guide the vertical prestressed cable into position along the inside corner of the watchtower, and connect it to the circumferential cable at the node with cable clamps, but do not apply the final design tension to the vertical cable at this time; S4: Overall synchronous tensioning and locking steps: After all system components are installed in place, the vertical prestressed cables are synchronously tensioned in stages to make their tension reach the design value, thereby driving the entire system to work together and forming prestressed constraints on the watchtower masonry. Then, the anchors at the ends of the vertical cables are locked. S5: Long-term monitoring and maintenance adjustment steps: Set long-term monitoring points at the anchorages of the vertical prestressed cable system, monitor the cable force regularly, and adjust the cable force according to the monitoring data to maintain system efficiency.

10. A construction method for a prestressed stabilization system for Tibetan and Qiang ancient stone watchtowers according to claim 9, characterized in that: In step S1, according to F total Determine the design preload F of a single circumferential cable. pre According to formula F break ≥γ*F pre A safety factor γ of not less than 2.5 is selected to determine and choose the specifications for the circumferential and vertical cables, where F break The nominal breaking force of the cable; Based on the local bearing capacity calculation formula σ c =F pre / A con ≤ψ*f c Design the dimensions of the angle steel and rubber pad in the corner joint, where σ c For local compressive stress on the stone surface, A con f is the contact area between the angle steel / rubber pad and the stone. c Here, ψ represents the standard value of the stone's compressive strength, and ψ is the high-strength reduction factor for the cultural relic itself, ranging from 0.3 to 0.5; based on the bending stiffness requirement E of the inner ring beam... _s *I _s ≥η*E _m *I _m Design the cross-section of the inner ring steel beam, where E _s *I _s E represents the bending stiffness of the steel ring beam section. _m *I _m The equivalent bending stiffness of the reinforced section of the watchtower wall is η, which is a stiffness multiple not less than 5; the strength verification formula for the through-bar is σ=F. pre / A≤f The design specifies the tie rod specifications, where σ is the calculated stress of the tie rod, A is the effective cross-sectional area at the thread of the tie rod, and f is the design value of the tensile strength of the tie rod material; based on the above design results, prepare all system components.

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