Discontinuous reinforcement method for mortar in mortar joint of ancient building masonry

Abstract

According to the discontinuous reinforcement method for the mortar in the masonry mortar joints of the ancient building, the original mortar and the reinforcing mortar are alternately filled in the masonry mortar joints, so that the bearing capacity and the anti-seismic property of the structure are enhanced. The method comprises the key steps of construction area column division, drill hole design, grouting design optimization, grouting parameter determination, duct preparation, reinforcement mortar injection and grouting effect evaluation. Particularly, the drilled holes are designed to be rectangular holes with the width of 90 mm, the hole depth penetrates through the test piece, and the distance between the holes is 90 mm. Grouting design optimization considers the rheological property of grout, the interaction between the building blocks and mortar is analyzed, and the cleaning mode and grouting hole arrangement are optimized. Grouting parameter determination relates to key indexes such as slurry diffusion radius and grouting pressure. The method effectively improves the structural safety on the premise of not destroying the style and appearance of the ancient building, has the advantages of simplicity and convenience in construction, low cost, quick effect and the like, and has important significance in protecting historical and cultural heritage.

Description

Technical Field

[0001] The invention relates to the technical field of ancient building repair, and in particular to a method for discontinuously reinforcing mortar joints of masonry of ancient buildings. Background Art

[0002] In the investigation of existing houses and historical and cultural buildings, it was found that masonry is affected by various natural factors, such as weathering, leakage, and plaster layer shedding, and the mortar becomes weak or the mortar strength is greatly reduced, especially for lime clay mortar masonry, the mortar is basically strengthless, while the strength of masonry blocks such as sintered bricks remains at the original level. The tensile and shear strength of masonry has little to do with the blocks. It depends on the mortar strength grade between the blocks and the contact surface between the mortar and the blocks. If the mortar strength is increased, it will have a great effect on improving the strength of masonry. By increasing the mortar strength, the shear and tensile properties of masonry are significantly improved, and the compressive properties are also improved by about 10%.

[0003] Grouting refers to the process of preparing a certain material into a slurry and pouring it into a reinforcement body using a pressure-feeding device to diffuse, gel or solidify it, so as to achieve the purpose of reinforcement or anti-seepage and plugging. There is little research and application of grouting reinforcement technology for masonry structures with poor wall or masonry mortar fullness or low masonry mortar strength grade, and the project implementation faces many problems. In order to establish a complete set of grouting reinforcement technology for masonry structures, it is very necessary to carry out special research. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a method for discontinuous reinforcement of mortar joints in ancient building masonry, which is implemented by the following technical solutions:

[0005] A method for discontinuously reinforcing mortar joints of masonry in ancient buildings comprises discontinuously replacing reinforcing mortar on masonry joints in the same length direction, that is, original mortar and reinforcing mortar are alternately formed to form complete masonry joints. The method comprises the following steps:

[0006] Step 1: Construction zone division: The vertical construction zones are divided along the length direction of the masonry wall of the ancient building according to the width a, where the width a is less than the length of the masonry;

[0007] Step 2: Drilling design: Use drilling tools to drill holes on masonry components according to the designed hole shape and hole spacing;

[0008] Step 3: Grouting design optimization: Based on the rheological properties of the slurry, combined with the penetration and compaction process of the slurry in the mortar, analyze the mutual force characteristics of the blocks and mortar, and optimize the design of the original mortar cleaning method and grouting hole layout plan;

[0009] Step 4: Determine the grouting parameters: including grouting design procedures, design content, grouting scheme, grouting technical indicators, grouting materials and formula design, slurry diffusion radius, grouting hole layout and grouting pressure;

[0010] Step 5: Hole preparation: After determining the hole position with a level ruler, perform row drilling in the vertical construction area in intervals, drill holes of specified size, remove mortar debris in the hole, rinse the wall, and moisten the bricks and mortar in the hole;

[0011] Step 6: Inject reinforcement mortar: Use an injection machine to inject reinforcement mortar into the hole and squeeze it to make it dense;

[0012] Step 7: Evaluation of grouting effect: Check the grouting effect through observation, mechanical index testing and displacement inference method.

[0013] Furthermore, the drilling design also includes: the designed hole type is a rectangular hole with a width of 90 mm, a height equal to the thickness of the mortar joint, a hole depth that passes through the specimen, and a hole spacing of 90 mm.

[0014] Furthermore, the grouting design optimization also includes: following the steps below:

[0015] (1) Slurry rheology analysis: This is done by applying fluid mechanics theory and capillary group theory to derive the grouting formula applicable to the current engineering conditions and analyze the application range and determination method of the parameters;

[0016] (2) Comparison of grouting theories: Grouting theories include penetration grouting, compaction grouting, and electrochemical grouting, which are selected and optimized according to current engineering requirements and geological conditions;

[0017] (3) Analysis of the mutual force between bricks and mortar: The force state of bricks and mortar in brick masonry is coordinated with each other. Bricks bear the main vertical load, while mortar plays the role of connecting and transferring loads. When designing the grouting scheme, the influence of the mechanical properties of mortar on the bearing capacity and stability of brick masonry should be considered;

[0018] (4) Optimization of the cleaning method of the original mortar: Before the grouting reinforcement design, indoor slurry ratio test and on-site grouting test should be carried out to determine the design parameters and verify the construction methods and equipment; this includes the method of cleaning the original mortar to ensure effective bonding between the new and old mortars;

[0019] (5) Optimization of grouting hole layout: The optimization of grouting hole layout is achieved by combining theoretical calculation with actual measurement results. When conducting on-site grouting tests, bricks with different characteristics are selected and a variety of grouting methods are used to obtain the slurry diffusion radius under different conditions. The on-site grouting test adopts triangular or rectangular hole layout.

[0020] Furthermore, the grouting parameter determination also includes:

[0021] (1) Grouting design procedure: including the determination of the design parameters of grouting diffusion radius, grouting pressure and single-hole grouting volume;

[0022] (2) Design content: Before design, indoor slurry mix test and on-site grouting test are carried out to determine the design parameters and test the construction methods and equipment;

[0023] (3) Grouting plan: including the selection of grouting method and grouting material, taking into account the project site conditions and the nature of the project itself;

[0024] (4) Grouting technical indicators: The technical indicators of slurry include viscosity, fluidity, density and stability;

[0025] (5) Slurry material and formula design: determined by materials and construction equipment;

[0026] (6) Slurry diffusion radius: When grouting with ordinary flower tubes, the diffusion radius r is estimated according to the formula r = 2kptln (r1 / r0), where k is the soil permeability coefficient, p is the grouting pressure, t is the grouting time, r1 is the outer boundary radius of the slurry diffusion, and r0 is the radius of the ordinary flower tube;

[0027] (7) Grouting hole arrangement: The grouting hole arrangement takes into account factors such as hole diameter, hole depth, and hole spacing to ensure that the grouting material can fully penetrate into the hole;

[0028] (8) Grouting pressure: The grouting pressure is determined based on field tests and is controlled at 0.4 MPa to 1.0 MPa.

[0029] The discontinuous reinforcement method of the mortar joints of the ancient building masonry of the present invention has the following significant beneficial effects:

[0030] (1) Through the discontinuous grouting reinforcement technology, the strength of the new masonry joints formed by the addition of reinforcing mortar is significantly improved, without the need to completely remove the masonry joints, reducing the disturbance to the masonry of the ancient building and effectively enhancing the bearing capacity and seismic performance of the masonry structure. Compared with the traditional "binding" reinforcement method, the grouting reinforcement technology does not require changing the original appearance and structural system of the building, and realizes structural reinforcement without destroying the historical and cultural heritage.

[0031] (2) Enhanced shear and compressive bearing capacity: After the grouting reinforcement method was used to replace the mortar joints, the masonry structure became more stable when subjected to shear force, significantly reducing the structural safety risk caused by shear failure. The compressive bearing capacity of the reinforced masonry is higher than the original one, which means that the structure is more stable when subjected to vertical loads, which is of great significance for improving the service life and safety of ancient buildings.

[0032] (3) Significant economic benefits: The grouting reinforcement technology used in the present invention has simple construction equipment, small scale, low cost, flexible and convenient construction, short construction period, and quick results, which greatly reduces construction costs and has significant economic benefits. Significant social benefits: By scientifically protecting and reinforcing local buildings and historical buildings, it not only improves the service life of the building, but also protects historical and cultural heritage. It has huge social benefits for improving urban civilization and comprehensive quality, promoting regional economic development and social spiritual civilization construction. Environmentally friendly: The grouting reinforcement technology has low noise and vibration during construction, has little impact on the surrounding environment, and meets the environmental protection requirements of modern cities. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the implementation modes of the present application, the drawings required for use in the description of the implementation modes will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a schematic diagram of the original mortar distribution of the present invention.

[0035] Figure 2 It is a schematic diagram of the vertical construction area array area of ​​the present invention.

[0036] Figure 3 This is a schematic diagram of the completion of discontinuous reinforcement of mortar joints in the masonry of an ancient building.

[0037] Description of reference numerals:

[0038] 100-original mortar, 101-reinforced mortar, 102-vertical construction area column. DETAILED DESCRIPTION

[0039] The following description of the embodiments will help the public better understand the present invention, but the specific embodiments given by the applicant cannot and should not be regarded as limitations on the technical solutions of the present invention. Any changes to the definitions of components or technical features, or formal rather than substantive changes to the overall structure should be regarded as the scope of protection defined by the technical solutions of the present invention.

[0040] In this application, unless otherwise clearly specified or limited, the terms "installation", "connection", "fixation" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements, or it can be only surface contact, or surface contact connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] Embodiment 1:

[0042] A method for discontinuously reinforcing mortar joints of ancient building masonry, comprising discontinuously replacing reinforcing mortar 101 on masonry joints in the same length direction, that is, the original mortar 100 and the reinforcing mortar 101 are alternately formed into a complete masonry joint, and the method comprises the following steps:

[0043] Step 1: Construction zone column division: The masonry wall of the ancient building is divided into vertical construction zone columns 102 according to the width a along the length direction, wherein the width a is less than the length of the masonry;

[0044] Step 2: Drilling design: Use drilling tools to drill holes on masonry components according to the designed hole shape and hole spacing;

[0045] Step 3: Grouting design optimization: Based on the rheological properties of the slurry, combined with the penetration and compaction process of the slurry in the mortar, the mutual force characteristics of the blocks and the mortar are analyzed, and the cleaning method of the original mortar 100 and the grouting hole arrangement plan are optimized;

[0046] Step 4: Determine the grouting parameters: including grouting design procedures, design content, grouting scheme, grouting technical indicators, grouting materials and formula design, slurry diffusion radius, grouting hole layout and grouting pressure;

[0047] Step 5: preparation of the hole: after the hole position is determined by a level ruler, the vertical construction area row 102 is subjected to row-by-row drilling construction to drill holes of a specified size, the mortar fragments in the hole are removed, the wall surface is washed, and the bricks and mortar in the hole are moistened;

[0048] Step 6: Injecting reinforcement mortar 101: Use an injection machine to inject reinforcement mortar 101 into the hole and squeeze it to make it dense;

[0049] Step 7: Evaluation of grouting effect: Check the grouting effect through observation, mechanical index testing and displacement inference method.

[0050] Furthermore, the drilling design also includes: the designed hole type is a rectangular hole with a width of 90 mm, a height equal to the thickness of the mortar joint, a hole depth that passes through the specimen, and a hole spacing of 90 mm.

[0051] Furthermore, the grouting design optimization also includes: following the steps below:

[0052] (1) Slurry rheology analysis: This is done by applying fluid mechanics theory and capillary group theory to derive the grouting formula applicable to the current engineering conditions and analyze the application range and determination method of the parameters;

[0053] (2) Comparison of grouting theories: Grouting theories include penetration grouting, compaction grouting, and electrochemical grouting, which are selected and optimized according to current engineering requirements and geological conditions;

[0054] (3) Analysis of the mutual force between bricks and mortar: The force state of bricks and mortar in brick masonry is coordinated with each other. Bricks bear the main vertical load, while mortar plays the role of connecting and transferring loads. When designing the grouting scheme, the influence of the mechanical properties of mortar on the bearing capacity and stability of brick masonry should be considered;

[0055] (4) Optimization of the cleaning method of the original mortar 100: Before the grouting reinforcement design, indoor slurry ratio test and on-site grouting test should be carried out to determine the design parameters and verify the construction methods and equipment; this includes the method of cleaning the original mortar 100 to ensure effective bonding between the new and old mortars;

[0056] (5) Optimization of grouting hole layout: The optimization of grouting hole layout is achieved by combining theoretical calculation with actual measurement results. When conducting on-site grouting tests, bricks with different characteristics are selected and a variety of grouting methods are used to obtain the slurry diffusion radius under different conditions. The on-site grouting test adopts triangular or rectangular hole layout.

[0057] Furthermore, the grouting parameter determination also includes:

[0058] (1) Grouting design procedure: including the determination of the design parameters of grouting diffusion radius, grouting pressure and single-hole grouting volume;

[0059] (2) Design content: Before design, indoor slurry mix test and on-site grouting test are carried out to determine the design parameters and test the construction methods and equipment;

[0060] (3) Grouting plan: including the selection of grouting method and grouting material, taking into account the project site conditions and the nature of the project itself;

[0061] (4) Grouting technical indicators: The technical indicators of slurry include viscosity, fluidity, density and stability;

[0062] (5) Slurry material and formula design: determined by materials and construction equipment;

[0063] (6) Slurry diffusion radius: When grouting with ordinary flower tubes, the diffusion radius r is estimated according to the formula r = 2kptln (r1 / r0), where k is the soil permeability coefficient, p is the grouting pressure, t is the grouting time, r1 is the outer boundary radius of the slurry diffusion, and r0 is the radius of the ordinary flower tube;

[0064] (7) Grouting hole arrangement: The grouting hole arrangement takes into account factors such as hole diameter, hole depth, and hole spacing to ensure that the grouting material can fully penetrate into the hole;

[0065] (8) Grouting pressure: The grouting pressure is determined based on field tests and is controlled at 0.4 MPa to 1.0 MPa.

[0066] Embodiment 2:

[0067] Some experimental studies were completed using the discontinuous grouting reinforcement method.

[0068] Main reinforcement process: This test uses a drilling machine to drill holes on masonry components according to the designed hole shape and hole spacing. Among them, the designed hole shape is a rectangular hole with a width of 90mm, a height of the mortar joint thickness, a hole depth that passes through the specimen, and a hole spacing of 90. The specific operation is: Step 1: Use a level ruler to determine the hole position and spacing on the masonry specimen, and then use a drilling machine to drill holes with a width of 90mm and a depth of the specimen thickness at the corresponding position; Step 2: Remove mortar fragments, rinse the wall with clean water, remove debris in the channel, and moisten the bricks and mortar in the channel to ensure adhesion with the new mortar; Step 3: Use an injection machine to inject reinforcement mortar 101 into the channel and squeeze it densely.

[0069] In view of the particularity of this method, there are three main requirements for the performance of reinforced mortar 101: a. high strength; b. strong bonding force to ensure bonding with the blocks; c. good working performance: moderate consistency can be easily injected, and the mortar can not flow out after injection. In the test, it was found that ordinary cement mortar was difficult to meet the requirements, so the materials we selected were: the test raw material we selected was po32.5 ordinary silicate cement, which has good stability and no agglomeration; plus 0## glue crystal from Beijing Huaqian Company as an additional admixture (with the effect of reducing water and increasing the strength of mortar); coarse sand with a fineness modulus of 3.5; tap water was used. Since the price of glue crystal is 5 times that of cement, in order to save costs, its addition amount is minimized while ensuring the various properties of reinforced mortar 101. After repeated trial mixing, the mortar requirements of this process were met. The average compressive strength of the mortar test block is 18.3MPa.

[0070] The test was conducted with two groups of compression and shear specimens, each with three specimens, which were divided into Group A and Group B according to whether they were reinforced or not. The test was conducted in the laboratory.

[0071] After the grouting reinforcement method was used to replace the mortar in the joints, the shear bearing capacity of the shear specimens could be increased by 209%, and the compressive bearing capacity of the masonry specimens could be increased by 25%, with a good reinforcement effect.

[0072] The failure process of masonry specimens reinforced by grouting under shear and compression is similar to that of unreinforced masonry specimens, but there are significant differences in the failure surface conditions and the locations of cracks.

[0073] From the perspective of shear specimens, the shear failure surface of the reinforced specimens occurred on the brick surface, that is, the shear capacity of the bricks was fully utilized and sheared, indicating that the shear capacity of the blocks was fully utilized, because grouting can only improve the bonding strength of the original mortar 100 and the bricks and cannot improve the bearing capacity of the bricks.

[0074] From the perspective of compression specimens, the crack distribution of reinforced specimens is more distinctive, and most of them are distributed at the junction of the reinforced mortar 101 and the original mortar 100; and because the reinforced mortar 101 has a high ability to resist deformation, it has a lateral restraining effect on the bricks, which indirectly improves the bearing capacity of the bricks.

[0075] Those skilled in the art should understand that those skilled in the art can implement variations by combining the prior art and the above embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present invention, and will not be described in detail here.

[0076] The preferred embodiments of the present invention are described above. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can use the above-disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for discontinuously reinforcing mortar joints of masonry of ancient buildings, comprising discontinuously replacing reinforcing mortar (101) on masonry joints in the same length direction, that is, the original mortar (100) and the reinforcing mortar (101) are alternately formed to form a complete masonry joint, characterized in that: The method comprises the following steps: Step 1: Construction zone division: vertical construction zone columns (102) are divided along the length direction of the masonry wall of the ancient building according to the width a, wherein the width a is less than the length of the masonry; Step 2: Drilling design: Use drilling tools to drill holes on masonry components according to the designed hole shape and hole spacing; Step 3: Grouting design optimization: Based on the rheological properties of the slurry, combined with the penetration and compaction process of the slurry in the mortar, the mutual force characteristics of the blocks and the mortar are analyzed, and the cleaning method of the original mortar (100) and the grouting hole arrangement scheme are optimized; Step 4: Determine the grouting parameters: including grouting design procedures, design content, grouting scheme, grouting technical indicators, grouting materials and formula design, slurry diffusion radius, grouting hole layout and grouting pressure; Step 5: hole preparation: after the hole position is determined by a level ruler, the vertical construction area row (102) is subjected to row-by-row drilling construction to drill holes of a specified size, remove mortar debris in the hole, wash the wall surface, and moisten the bricks and mortar in the hole; Step 6: injecting reinforcement mortar (101): injecting reinforcement mortar (101) into the hole using an injection machine, and squeezing it to make it dense; Step 7: Evaluation of grouting effect: Check the grouting effect through observation, mechanical index testing and displacement inference method.

2. The method for discontinuously reinforcing the mortar joints of ancient building masonry as claimed in claim 1, characterized in that: The drilling design also includes: the designed hole type is a rectangular hole with a width of 90mm, a height equal to the thickness of the mortar seam, a hole depth that passes through the specimen, and a hole spacing of 90mm.

3. The method for discontinuously reinforcing the mortar joints of ancient building masonry as claimed in claim 1, characterized in that: Grouting design optimization also includes: following these steps: (1) Slurry rheology analysis: This is done by applying fluid mechanics theory and capillary group theory to derive the grouting formula applicable to the current engineering conditions and analyze the application range and determination method of the parameters; (2) Comparison of grouting theories: Grouting theories include penetration grouting, compaction grouting, and electrochemical grouting, which are selected and optimized according to current engineering requirements and geological conditions; (3) Analysis of the mutual force between bricks and mortar: The force state of bricks and mortar in brick masonry is coordinated with each other. Bricks bear the main vertical load, while mortar plays the role of connecting and transferring loads. When designing the grouting scheme, the influence of the mechanical properties of mortar on the bearing capacity and stability of brick masonry should be considered; (4) Optimization of the cleaning method of the original mortar (100): Before the grouting reinforcement design, indoor slurry ratio test and on-site grouting test should be carried out to determine the design parameters and verify the construction methods and equipment; this includes the method of cleaning the original mortar (100) to ensure effective bonding between the new and old mortars; (5) Optimization of grouting hole layout: The optimization of grouting hole layout is achieved by combining theoretical calculation with actual measurement results. When conducting on-site grouting tests, bricks with different characteristics are selected and a variety of grouting methods are used to obtain the slurry diffusion radius under different conditions. The on-site grouting test adopts triangular or rectangular hole layout.

4. The method for discontinuously reinforcing the mortar joints of ancient building masonry as claimed in claim 1, characterized in that: Grouting parameter determination also includes: (1) Grouting design procedure: including the determination of the design parameters of grouting diffusion radius, grouting pressure and single-hole grouting volume; (2) Design content: Before design, indoor slurry mix test and on-site grouting test are carried out to determine the design parameters and test the construction methods and equipment; (3) Grouting plan: including the selection of grouting method and grouting material, taking into account the project site conditions and the nature of the project itself; (4) Grouting technical indicators: The technical indicators of slurry include viscosity, fluidity, density and stability; (5) Slurry material and formula design: determined by materials and construction equipment; (6) Slurry diffusion radius: When grouting with ordinary flower tubes, the diffusion radius r is estimated according to the formula r = 2kptln (r1 / r0), where k is the soil permeability coefficient, p is the grouting pressure, t is the grouting time, r1 is the outer boundary radius of the slurry diffusion, and r0 is the radius of the ordinary flower tube; (7) Grouting hole arrangement: The grouting hole arrangement takes into account factors such as hole diameter, hole depth, and hole spacing to ensure that the grouting material can fully penetrate into the hole; (8) Grouting pressure: The grouting pressure is determined based on field tests and is controlled at 0.4 MPa to 1.0 MPa.

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