Ancient building wood column double dovetail mortise type pier joint repair structure and method
By combining the double dovetail tenon-and-mortise joint structure with the epoxy resin adhesive layer, the problems of weak bending load-bearing capacity and corrosion prevention in the jointing of wooden columns in ancient buildings are solved, achieving high-efficiency connection strength and protection of ancient buildings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA RAILWAY CONSTRUCTION ENGINEERING GROUP
- Filing Date
- 2026-05-15
- Publication Date
- 2026-07-21
AI Technical Summary
Traditional methods of connecting wooden pillars in ancient buildings have weak bending load-bearing capacity, are prone to displacement or cracking, and exposed iron hoops damage the ancient charm of the building. Furthermore, the connection nodes have poor anti-corrosion and sealing properties, making it impossible to balance the protection of ancient buildings with mechanical performance.
The structure adopts a double dovetail tenon-and-mortise joint, which forms a sealed protective layer by setting cross-interlocking dovetail grooves and dovetail blocks on the end faces of the upper and lower columns, combined with epoxy resin adhesive and corrosion-resistant iron hoops. The iron hoops are hidden under the subsequent paint surface to ensure connection strength and durability.
It significantly improves the bending, shear and pull-out bearing capacity of the joint, enhances the durability of the joint, preserves the historical appearance of the ancient building, and is convenient, efficient and efficient to construct with low material consumption.
Smart Images
Figure CN122428796A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ancient building wooden structure repair technology, and in particular to a double dovetail mortise and tenon joint repair structure and method for ancient building wooden columns. Background Technology
[0002] Due to their age, ancient wooden pillars often suffer from diseases such as root rot, insect infestation, and cracking, requiring repair by piling and splicing. This involves replacing the rotten parts with new wood while preserving the original, intact upper part of the pillar.
[0003] Traditional pier-jointing methods often employ flat joints or simple overlaps, secured with several iron hoops. This approach has significant drawbacks: the joints have weak bending resistance and are prone to relative displacement or cracking under horizontal loads; the exposed iron hoops damage the building's antique charm, and the poor corrosion resistance and sealing of the joints allow moisture to easily penetrate, leading to secondary decay. While replacing the entire wooden column can restore load-bearing capacity, it severely violates the principle of "restoring the old as it was" in cultural relic preservation, failing to retain historical information. Therefore, there is an urgent need for a pier-jointing repair structure and method that meets the requirements for ancient building preservation while significantly improving the mechanical properties and durability of the joints. Summary of the Invention
[0004] In order to overcome the problem that the existing pier connection process relies heavily on iron hoops for binding and fixing, resulting in weak bending resistance at the joint between the upper and lower columns.
[0005] The technical solution of this invention is as follows: a double dovetail tenon-and-mortise joint repair structure for ancient building wooden columns, comprising a retained upper column and a lower column for replacing the rotten part. The bottom end face of the upper column is provided with a first half tenon, which includes a first dovetail groove protruding outward from the upper column body and a second dovetail groove recessed inward. The top end face of the lower column is provided with a second half tenon that is inserted and fitted into the first half tenon, which includes a first dovetail block that mates with the first dovetail groove and a second dovetail block that mates with the second dovetail groove. The upper column and the lower column are connected by the first dovetail block being inserted into the first dovetail groove and the second dovetail block being inserted into the second dovetail groove, forming a double dovetail cross-interlocking connection. An epoxy resin adhesive layer is filled in the splicing gap, and multiple corrosion-resistant iron hoops are tightly attached to the surface of the wooden column on the outer periphery of the joint area.
[0006] Preferably, the dovetail slope angles of the first dovetail groove and the second dovetail block are both 45° to 60°, and the corresponding dovetail groove angles match, with a tenon-and-mortise fit clearance of 0.5mm to 1mm. The dimensions and positions of the dovetail blocks and dovetail grooves in the upper and lower columns are determined based on parametric lofting of the BIM model and precisely machined by CNC machine tools.
[0007] Preferably, the epoxy resin adhesive layer also fills the tiny gaps between the iron hoop and the surface of the wooden column, forming a sealed protective layer, with both ends of the iron hoop flush with the surface of the wooden column. The iron hoops are symmetrically positioned 5cm to 8cm above and below the splice joint, with a spacing of 15cm to 20cm.
[0008] Preferably, the device also includes an installation groove, a slot, a wedge block, and an elastic element. The first and second dovetail grooves are each provided with an installation groove. A wedge block is slidably disposed inside the installation groove. An elastic element is disposed at the tail of the wedge block. Slots are provided at the positions of the first and second dovetail blocks corresponding to the installation grooves. The wedge blocks are adapted to engage with the slots. The wedge surfaces of the two sets of wedge blocks have the same direction.
[0009] Preferably, the first and second tenons are provided with circular grooves at the corresponding mounting groove and slot positions, and a cylindrical block is rotatably arranged inside the circular groove.
[0010] Preferably, the cylindrical block and the wedge block have an arc-shaped groove at the intersection, and one side of the inner wall of the arc-shaped groove has an arched structure. The wedge block has a notch on the side corresponding to the mounting groove at the first tenon. When the wedge block is fully inserted into the slot, the arched part of the arc-shaped groove of the cylindrical block abuts against the inner wall of the notch of the wedge block.
[0011] Based on the above structure, the present invention also provides a method for repairing double dovetail mortise and tenon joints of wooden pillars in ancient buildings, including the following steps: Step 1: Structural Inspection and Cleaning Damage inspection was performed on the rotten wooden pillars, the extent of rot was marked, the lower rotten part was removed, and the intact upper part of the original pillar was retained as the upper pillar; the lower end of the upper pillar was cleaned to make it flat and firm, and the moisture content of the cross section was controlled below 12%.
[0012] Step 2: Mortise and Tenon Design and Fabrication Based on the measured data, a BIM model was constructed to determine the geometric parameters of the double dovetail tenon and mortise joints at the bottom of the upper column and the top of the lower column. According to the processing drawings exported from the model, the first half tenon was processed at the bottom of the upper column and the second half tenon was processed at the top of the lower column. After processing, trial assembly and adjustment were performed to ensure that the tenon and mortise joint gap met the design requirements.
[0013] Step 3: Temporary support erection Temporary support frames are erected around the wooden pillars to be repaired. Adjustable top supports are used to hold the upper pillars tightly, transferring the load of the upper pillars to the foundation and keeping the upper pillars stable.
[0014] Step 4: Apply adhesive and fix with anchors Prepare epoxy resin on site, apply the adhesive evenly to the surface of the first half tenon of the upper column and the second half tenon of the lower column, then precisely align the lower column with the upper column from bottom to top, so that the double dovetail tenon is fully fitted; fit iron hoops around the joint and tighten them symmetrically and evenly, remove the excess adhesive squeezed out, and let it stand to cure.
[0015] Step 5: Surface Treatment and Maintenance After the epoxy resin has fully cured, the joint area and the surface of the iron hoop are sanded, coated with anti-corrosion and fireproof paint, and distressed to make them match the color and texture of the original wooden pillars. After completion, they are kept for no less than 7 days, during which time disturbance and external forces are avoided.
[0016] Preferably, step two specifically includes: drying new wood to a moisture content of 8% to 12%; precisely machining the first and second dovetail blocks on the top surface of the lower column; machining matching first and second dovetail grooves on the bottom surface of the upper column; controlling the angle of the dovetail bevel to 45° to 60°; and checking the fit gap to be 0.5mm to 1mm using a feeler gauge; after machining, trial assembling the upper and lower columns, and checking the verticality and coaxiality using a level and a theodolite, and manually making minor adjustments to any unqualified areas.
[0017] Preferably, in step four, the epoxy resin adhesive is applied along the wood grain direction, with a uniform coating thickness, and the connection and iron hoop installation are completed before the adhesive initially sets; before installing the iron hoop, the design spacing is marked for positioning, and a symmetrical and gradual force is applied during tightening to ensure that the iron hoop adheres to the surface of the wooden column without warping.
[0018] Preferably, in step five, the specific surface treatment process is as follows: sanding the joint and wooden column surface, filling nail holes and micro-cracks with epoxy putty, applying two coats of ACQ preservative, applying two coats of fire-retardant paint, applying two coats of putty and sanding, applying two coats of paint, applying one coat of paint, applying multiple coats and sanding to finally form the topcoat; during the curing period, the ambient temperature is 5℃~35℃ and the relative humidity is 60%~70%.
[0019] The beneficial effects of this invention are: The double dovetail cross tenon and mortise structure with horizontal bidirectional mutual restraint greatly improves the bending, shear and pull-out bearing capacity of the joint. Combined with epoxy resin bonding and external iron hoop restraint, the new and old wooden columns form a continuous and complete force system, effectively restoring the original structural performance of the column. Epoxy resin fills the micro-gaps, which not only enhances the adhesion but also seals and waterproofs, and prevents corrosion, significantly improving the durability of the joints. The iron hoops are hidden under the subsequent paint surface, and with the aging treatment, there are no exposed reinforcement marks, perfectly preserving the historical appearance of the ancient building. Through precise BIM modeling and CNC machining, high-precision mortise and tenon joints are ensured, making construction convenient and efficient, reducing material waste, and saving energy and protecting the environment; the overall process is highly standardized. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the double dovetail tenon-and-mortise joint repair structure of the present invention. Figure 2 for Figure 1 A schematic diagram of the overall front view of the unfolded structure before the connection between the upper and lower columns and the lower column pier; Figure 3 for Figure 1 A schematic diagram of the overall unfolded structure before the connection between the upper and lower columns and the lower column base; Figure 4 This is a schematic diagram of the cylindrical block of the double dovetail tenon-and-mortise joint repair structure of the present invention. Figure 5 This is a flowchart illustrating the repair method of the present invention.
[0021] Explanation of reference numerals in the attached drawings: 1. Upper column; 11. First half-tenon; 111. First dovetail groove; 112. Second dovetail groove; 2. Lower column; 21. Second half-tenon; 211. First dovetail block; 212. Second dovetail block; 3. Epoxy resin adhesive layer; 4. Iron hoop; 51. Mounting groove; 52. Slot; 53. Wedge block; 54. Elastic element; 55. Cylindrical block; 56. Circular groove. Detailed Implementation
[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0023] Example 1; This application can actually solve the problem of weak bending resistance of traditional upper and lower column connection nodes; In this embodiment, as Figure 1 and Figure 2 As shown, a double dovetail tenon-and-mortise joint repair structure for ancient wooden columns includes the upper section of the original wooden column (upper column 1) and a lower column 2 made from new wood. The bottom end face of the upper column 1 is machined with a first half-tenon 11, the structure of which is: a first dovetail groove 111 is formed by extending radially outward on one side of the end face to form a protruding position, while the opposite side is recessed inward to form a second dovetail groove 112. Correspondingly, a second half-tenon 21 is machined on the top end face of the lower column 2, which has a first dovetail block 211 that matches the contour of the first dovetail groove 111, and a second dovetail block 212 that matches the contour of the second dovetail groove 112. When the upper column 1 and lower column 2 are inserted, the first dovetail groove 111 is inserted into the first dovetail block 211, and simultaneously the second dovetail block 212 is inserted into the second dovetail groove 112. The two dovetails interlock in a crisscrossing arrangement on the cross-section of the column, forming a bidirectional interlocking double dovetail tenon-and-mortise joint. This structure can resist bending moments and shear forces from different directions simultaneously, preventing traditional flat joints from coming apart under lateral forces.
[0024] An epoxy resin adhesive layer 3 is applied between all tenon and mortise contact surfaces. This epoxy resin fills the cellular cavities and micro-grooves of the wood, and after curing, it bonds the upper column 1 and lower column 2 together, providing additional sealing. Four hot-dip galvanized iron hoops 4 are fitted around the outer perimeter of the joint area. The inner walls of the hoops are pressed tightly against the surface of the wooden columns, and some adhesive is squeezed into the gaps between the hoops and the wood to form a sealant. The hoops are located symmetrically above and below the joint, at 5cm and 8cm intervals, with a spacing of 15cm. The hoops are covered with paint in subsequent painting processes and are not exposed.
[0025] During processing, the dovetail slope angles of the first dovetail groove 111 and the second dovetail block 212 are both 55°, which can take into account both the interlocking strength and the shear resistance of the wood across the grain. The mortise and tenon joint gap is precisely controlled within 0.8mm by CNC machine tools. During trial assembly, feeler gauges are used to check each surface to ensure that it is easy to install and does not loosen.
[0026] Furthermore, to improve the bending, shear, and pull-out bearing capacity of the joint, refer to Figure 2 and Figure 3 It also includes an installation groove 51, a slot 52, a wedge block 53, and an elastic element 54. The first dovetail groove 111 and the second dovetail groove 112 are both provided with an installation groove 51. The wedge block 53 is slidably arranged inside the installation groove 51. The tail of the wedge block 53 is provided with an elastic element 54. The first dovetail block 211 and the second dovetail block 212 are both provided with slots 52 at positions corresponding to the installation groove 51. The wedge block 53 is adapted to engage with the slot 52. The wedge surfaces of the two sets of wedge blocks 53 are in the same direction.
[0027] It should be noted that the elastic element 54 can be a coil spring, a sheet spring, etc. In this embodiment, the elastic element 54 is a metal sheet spring. The wedge block 53 has a right-angled trapezoidal structure, and its length is just enough to be completely contained in the mounting groove 51. Before installation, the elastic element 54 is placed in the mounting groove 51, and then the tail end of the wedge block 53 is inserted along the mounting groove 51 so that the wedge block 53 is connected to the inner wall of the mounting groove 51 through the elastic element 54. The wedge surface directions of the two sets of wedge blocks 53 are kept consistent. Along the wedge surface direction of the wedge block 53, the dovetail grooves corresponding to the upper column 1 and the lower column 2 are aligned. As the tail block slides in, when the lower column 2 just slides in, the wedge surface of the wedge block 53 contracts into the mounting groove 51 under the thrust of the lower column 2. At this time, the elastic element 54 is compressed and stores energy. When the lower column 2 is fully slid in, the wedge block 53 corresponds to the slot 52, and the wedge block 53 is inserted into the slot 52 by the rebound force of the elastic element 54. At this time, the positions of the upper column 1 and the lower column 2 are locked. After being locked, the upper column 1 and the lower column 2 can still provide a certain supporting force under forces from all directions. They mutually limit each other in the horizontal two-way direction, which greatly improves the bending, shear and pull-out bearing capacity of the joint. As an optional implementation, the first half tenon 11 and the second half tenon 21 are provided with circular grooves 56 at the positions of the mounting groove 51 and the slot 52, and a cylindrical block 55 is rotatably disposed inside the circular groove 56.
[0028] When separating the locked upper column 1 and lower column 2, the cylindrical block 55 is inserted along the corresponding circular groove 56, and the wedge block 53 is pushed out of the slot 52 by the cylindrical block 55. Then the lower column 2 is moved out along the wedge surface direction, thereby separating the upper column 1 and lower column 2.
[0029] For the best option, please refer to [the following]. Figure 4 The cylindrical block 55 and the wedge block 53 have an arc-shaped groove at their intersection. One side of the inner wall of the arc-shaped groove has an arched structure. The mounting groove 51 at the first tenon 11 has a notch on one side of the wedge block 53. When the wedge block 53 is fully inserted into the slot 52, the arched part of the arc-shaped groove of the cylindrical block 55 abuts against the inner wall of the notch of the wedge block 53.
[0030] It should be noted that before installing the upper column 1 and lower column 2, insert the cylindrical block 55 into the circular groove 56, rotate the cylindrical block 55 to adjust it until the bottom surface of the arc-shaped groove is flush with the inner wall of the slot 52, and then slide the lower column 2 along the upper column 1. The installation method is the same as described above, and will not be elaborated further here. When the wedge block 53 is fully inserted into the slot 52, the arc-shaped groove of the cylindrical block 55 corresponds to the notch of the wedge block 53. At this time, the upper column 1 and lower column 2 are reinforced with iron hoops 4, which press against the position of the cylindrical block 55. To ensure that the cylindrical block 55 does not become loose, when disassembly is required, remove the iron hoop 4 and rotate the cylindrical block 55 in a half-turn manner, so that the arched part of the arc groove of the cylindrical block 55 presses against the notch of the wedge block 53. As the cylindrical block 55 rotates, the wedge block 53 is slowly lifted up. When the cylindrical block 55 has rotated half a turn, the wedge block 53 is completely pushed into the mounting groove 51, thereby separating the upper column 1 and the lower column 2, thus facilitating the installation and separation of the lower column and improving the efficiency of replacing and installing the lower column.
[0031] Reference Figure 5 The steps for repairing using the above structure are as follows: Step 1: Structural Inspection and Cleaning. On-site inspection, including visual inspection, tapping, and probe testing, is used to determine the extent of decay in the lower part of the upper column 1. The decayed section is removed, ensuring the remaining material is intact, the cut surface is smooth, and the wood moisture content is no more than 12%. The end face is then trimmed and sanded.
[0032] Step Two: Mortise and Tenon Design and Machining. Based on the cross-sectional dimensions and diameter of the upper column 1, a 3D model is created using BIM software to determine the specific shape, dovetail angle, and depth of the first half-tenon 11 and the second half-tenon 21. After exporting the machining drawings, the lower column 2 is machined from dried hardwood of the same material as the original column, and the corresponding dovetail blocks and dovetail grooves are milled on the bottom of the upper column 1 and the top of the lower column 2 using a precision woodworking machine. After machining, a ground test assembly is performed to check the verticality and alignment marks. If the fit is too tight, a fine planer is used to make minor adjustments until it inserts smoothly without any wobbling.
[0033] Step 3: Temporary support erection. Erect steel pipe support frames around the columns, with the spacing between the uprights not exceeding 1.5m and the step distance between the horizontal bars not exceeding 1.2m; install two clamps at appropriate positions above and below the upper column 1, and transfer the load of the upper column to the support frame through adjustable top bracing to ensure structural stability and safety during subsequent column cutting and replacement.
[0034] Step 4: Applying adhesive and fixing the joint. Prepare a low-viscosity epoxy resin adhesive and apply it evenly to all contact surfaces of the first half tenon 11 and the second half tenon 21. Align the lower column 2 with the upper column 1 and slowly push it upwards in the vertical direction to make the dovetail tenon engage. Use a wooden hammer to tap lightly for assistance. Immediately insert the iron hoop 4 and adjust the position according to the marked positioning lines. Tighten the bolts symmetrically one by one. Wipe away any excess adhesive that is squeezed out immediately. Let it stand at room temperature for 24 hours until the epoxy resin has initially cured.
[0035] Step 5: Surface Treatment and Maintenance. After the epoxy resin has fully cured, first sand the joint area and the edge of the iron hoop, and fill the nail holes and gaps with epoxy putty. Then, apply two coats of ACQ anti-corrosion agent, two coats of fire-retardant paint, two coats of putty and sand them smooth, apply two coats of oil stain, apply one coat of oil stain and sand it smooth, and then apply the topcoat in three layers and lightly sand it to finally form a paint surface that matches the original appearance of the column. During the maintenance period, control the ambient humidity at about 65% and the temperature at 20℃~30℃ for 7 days. During this period, collisions and loading are strictly prohibited. After the maintenance is completed, remove the temporary supports and the wooden column can be used normally again.
[0036] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A double dovetail mortise and tenon joint repair structure for ancient building wooden columns, comprising a retained upper column (1) and a lower column (2) replacing the decayed portion, characterized in that: The bottom end face of the upper column (1) is provided with a first half tenon (11), the first half tenon (11) includes a first dovetail groove (111) protruding outward from the upper column (1) body and a second dovetail groove (112) recessed inward; the top end face of the lower column (2) is provided with a second half tenon (21) that is inserted and fitted into the first half tenon (11), the second half tenon (21) includes a first dovetail block (211) that cooperates with the first dovetail groove (111) and a second dovetail block (212) that cooperates with the second dovetail groove (112); the upper column (1) and the lower column (2) are connected by the first dovetail block (211) being inserted into the first dovetail groove (111) and the second dovetail block (212) being inserted into the second dovetail groove (112) to form a double dovetail cross-interlocking connection, the splicing gap is filled with an epoxy resin adhesive layer (3), and a corrosion-resistant iron hoop (4) is tightly attached to the surface of the wooden column on the outer periphery of the joint area.
2. The double dovetail mortise and tenon joint repair structure for ancient building wooden columns according to claim 1, characterized in that: The angle between the dovetail slope of the first dovetail groove (111) and the vertical surface of the second dovetail block (212) is 45° to 60°, and the angle of the corresponding dovetail groove matches it. The tenon and mortise fit gap is 0.5mm to 1mm.
3. The double dovetail mortise and tenon joint repair structure for ancient building wooden columns according to claim 2, characterized in that: The epoxy resin adhesive layer (3) also fills the gap between the iron hoop (4) and the surface of the wooden column. The iron hoop (4) is installed symmetrically at 5cm to 8cm above and below the splice joint, and the distance between adjacent iron hoops is 15cm to 20cm.
4. The double dovetail mortise and tenon joint repair structure for ancient building wooden columns according to claim 1, characterized in that: It also includes an installation groove (51), a slot (52), a wedge block (53), and an elastic element (54). The first dovetail groove (111) and the second dovetail groove (112) are both provided with an installation groove (51). The wedge block (53) is slidably arranged inside the installation groove (51). The tail of the wedge block (53) is provided with an elastic element (54). The first dovetail block (211) and the second dovetail block (212) are both provided with slots (52) at positions corresponding to the installation groove (51). The wedge block (53) and the slot (52) are adapted to engage. The wedge surfaces of the two sets of wedge blocks (53) are in the same direction.
5. The double dovetail mortise and tenon joint repair structure for ancient building wooden columns according to claim 4, characterized in that: The first half tenon (11) and the second half tenon (21) are provided with circular grooves (56) at the corresponding mounting grooves (51) and slots (52), and a cylindrical block (55) is rotatably provided inside the circular groove (56).
6. The double dovetail mortise and tenon joint repair structure for ancient building wooden columns according to claim 5, characterized in that: The cylindrical block (55) and the wedge block (53) intersect at an arc-shaped groove. One side of the inner wall of the arc-shaped groove has an arched structure. The wedge block (53) corresponding to the mounting groove (51) at the first tenon (11) has a notch. When the wedge block (53) is fully inserted into the slot (52), the arched part of the arc-shaped groove of the cylindrical block (55) abuts against the inner wall of the notch of the wedge block (53).
7. A method for repairing ancient building wooden pillars using double dovetail mortise and tenon joints, characterized in that: Repairing using the structure as described in any one of claims 1-6 includes the following steps: Step 1: Inspect and clean the rotten wooden pillars, cut off the lower rotten section, retain the upper pillar (1), and flatten the cut surface; Step 2: Construct a BIM model based on the measured data, design and process the first half tenon (11) at the bottom of the upper column (1), and process the second half tenon (21) at the top of the lower column (2) made of new wood, so that the two can form a double dovetail interlocking; Step 3: Erect a temporary support frame around the upper column (1) and fix and support the upper column (1) with adjustable top bracing. Step 4: Prepare epoxy resin adhesive and apply it evenly to the contact surfaces of the first half tenon (11) and the second half tenon (21). Connect the lower column (2) and the upper column (1) to make the double dovetail tenon fully fit. Then, put iron hoops (4) on the outer periphery of the joint and tighten them. Remove the excess adhesive and let it stand to cure. Step 5: After the epoxy resin has cured, grind the joint area and iron hoop, apply anti-corrosion and fireproof coating and aging treatment, and then cure for at least 7 days in an environment with a temperature of 5℃~35℃ and a relative humidity of 60%~70%.
8. The method for repairing ancient building wooden columns with double dovetail tenon and mortise joints according to claim 7, characterized in that: In step two, the first half tenon (11) includes a first dovetail groove (111) and a second dovetail groove (112), and the second half tenon (21) includes a first dovetail block (211) that fits the first dovetail groove (111) and a second dovetail block (212) that fits the second dovetail groove (112). The dovetail slope angle is 45° to 60°, and the tenon-mortise fit gap is controlled at 0.5mm to 1mm. After processing, a trial assembly is carried out, and the fit accuracy and perpendicularity are checked with feeler gauge, level and theodolite. Any unqualified parts are manually repaired until qualified.
9. A method for repairing ancient building wooden pillars using double dovetail tenon and mortise joints as described in claim 7, characterized in that: In step four, epoxy resin adhesive is applied along the wood grain. The butt joint and iron hoop installation are completed within one hour after application. When tightening the iron hoop, a symmetrical and gradual force is applied to ensure that the iron hoop adheres evenly to the surface of the wooden column.
10. A method for repairing ancient building wooden columns using double dovetail tenon and mortise joints according to claim 7, characterized in that: Step five, the surface treatment specifically includes: sanding the joints and the surface of the wooden column, filling defects with epoxy putty, applying two coats of ACQ preservative and two coats of fire-retardant paint in sequence, applying two coats of putty and sanding, applying two coats of oil stain, applying one coat of oil stain and sanding it smooth, and then applying multiple coats of finishing paint and sanding until a finish consistent with the texture of the column is formed; during the curing period, the ambient temperature and humidity are monitored in real time to avoid collisions, moisture and exposure to the sun.