A crack resistance design method for marine aggregate concrete based on mesoscopic fracture theory

Abstract

The present invention belongs to the technical field of bridges and water conservancy projects, and specifically relates to a method for designing anti-cracking of marine aggregate concrete based on mesoscopic fracture theory. A nonlinear anti-cracking model of marine aggregate concrete is designed based on the mesoscopic fracture theory. The tensile strength f of the concrete is tc Equal to the tensile strength f of the mortar tm Tensile strength increment Δf caused by bridging force with coarse aggregate t The anti-cracking calculation model of marine aggregate concrete constructed by the present invention is a method for determining macroscopic fracture parameters based on mesoscopic characteristics, which can be used through numerical simulation of finite element software. It is not only applicable to large-sized specimens, but also to small and medium-sized specimens; it is applicable to specimens with shallow and deep cracks; it is applicable to various marine load environments, and it can avoid the risk of serious degradation of bearing capacity and service life caused by concrete cracking in bridges, water conservancy and marine engineering, and has important engineering value.

Description

Technical Field

[0001] The invention belongs to the technical field of bridges and water conservancy projects, and in particular relates to a method for designing anti-cracking of marine aggregate concrete based on mesoscopic fracture theory. Background Art

[0002] Marine aggregate concrete is a type of concrete made from marine resources, including marine aggregates such as coral aggregates and sea sand, recycled aggregates from the demolition of existing buildings on offshore or deep islands and reefs, and concrete made from seawater or fresh water. Compared with ordinary concrete, marine aggregate concrete can effectively utilize marine resources and reduce the exploitation of land resources, which is of environmental significance. At the same time, it achieves local materials, avoids long-distance transportation of land resources, and reduces production and construction costs. Marine aggregate concrete has good applicability in bridge, water conservancy project, marine engineering and island and reef construction.

[0003] The environmental loads in water conservancy projects and marine projects are complex and changeable, making concrete more prone to cracking, which directly affects the stability and safety of the structure. Compared with natural crushed stone, coral coarse aggregate and recycled coarse aggregate contain more defects and better bond with the slurry, resulting in fractures often occurring in the coarse aggregate part rather than the bonding interface between the coarse aggregate and the slurry. This makes the brittleness of marine aggregate concrete more significant than that of ordinary concrete, which also means that the cracking of marine aggregate concrete is more sudden and rapid than that of ordinary concrete, and the harm caused by cracking is greater. Therefore, it is of great significance to accurately design the crack resistance of marine aggregate concrete. At present, the methods for crack resistance design of concrete are based on the macroscopic design method of linear elastic fracture theory and continuous medium mechanics to design the crack resistance of ordinary concrete. However, the composition of marine aggregate concrete is more complex than that of ordinary concrete, which is a non-uniform and non-continuous material. The previous macroscopic design method is obviously no longer applicable. It is necessary to consider the interaction between coarse aggregate and mortar in concrete and predict the tensile strength of concrete from the microscopic level. In order to better serve the "maritime power strategy" in the future, the scientific problem of microscopic crack resistance design of marine aggregate concrete needs to be solved urgently.

[0004] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a method for designing anti-cracking of marine aggregate concrete based on mesoscopic fracture theory.

[0006] The technical solution adopted by the present invention to solve the technical problem is as follows: a method for designing anti-cracking of marine aggregate concrete based on mesoscopic fracture theory, a nonlinear anti-cracking model of marine aggregate concrete based on mesoscopic fracture theory, and a tensile strength f of concrete. tc Equal to the tensile strength f of the mortar tm Tensile strength increment Δf caused by bridging force with coarse aggregate t The sum includes the following steps:

[0007] S1. Modeling: Modeling marine aggregate concrete and marine mortar and marine aggregate constituting marine aggregate concrete respectively. After modeling, the marine aggregate concrete model is referred to as concrete, the marine mortar model is referred to as mortar, and the marine aggregate model is referred to as coarse aggregate.

[0008] S2. Calculate the tensile strength f of the mortar tm ,

[0009] S3. Calculate the tensile strength increment Δf caused by the bridging force of coarse aggregate t ,

[0010] S4. According to Get the tensile strength of concrete f tc Predicted value.

[0011] Preferably, when the concrete reaches the maximum breaking load F maxc When the critical crack extension length The bridging effect of all coarse aggregates in the b , that is, the ultimate tensile strength or ultimate pull-out strength of aggregate, the critical crack extension length of mortar The nominal strength increment of the cohesive force is assumed to be a constant; considering the effects of the initial crack and the virtual crack, the nominal strength increment can be obtained:

[0012] ;

[0013] Depend on It can be seen from the relationship that the tensile strength increment Δf caused by the bridging force of coarse aggregate t The calculation formula is:

[0014] ;

[0015] in, is the concrete width; is the concrete height; is the initial joint length of concrete; is the average aggregate size of concrete, is the discrete coefficient that represents the discontinuous characteristics of concrete; is the average aggregate size of the mortar, is the discrete coefficient representing the discontinuous characteristics of the mortar, is the effective crack length.

[0016] Preferably, the effective crack length ;

[0017] In the formula, the coefficient , Seam height ratio , shape function:

[0018] .

[0019] Preferably, the joint height ratio of concrete is 0.1~0.5.

[0020] Preferably, the tensile strength f of the mortar is tm The calculation of the prefabricated crack mortar was carried out by three-point bending test to obtain F maxm and calculate the tensile strength f using the following formula tm ,

[0021] Three-point bending: ;

[0022] Equivalent cross-sectional area ;

[0023] , ;

[0024] In the formula, is the gravity of the mortar itself; F maxm is the maximum breaking load; is the mortar width; is the mortar height; is the support span; is the mortar joint height ratio, is the length of the mortar prefabricated joint, is the average aggregate size of the mortar, It is the discrete coefficient that represents the discontinuous characteristics of mortar.

[0025] Preferably, the predicted value range of tensile strength with a 95% guarantee rate is predicted by means of normal distribution, and the lower limit of the predicted value of tensile strength with a 95% guarantee rate is used as the design value of concrete crack resistance.

[0026] Preferably, the concrete in the method contains at least two or more phases of media, and the method is applicable to but not limited to concrete prepared with coral aggregate, sea sand and recycled coarse and fine aggregates.

[0027] Preferably, the forms of external loads causing concrete cracking include, but are not limited to, static loads, dynamic loads and fatigue loads.

[0028] Preferably, suitable for / ≥8 concrete models, is the concrete height, is the average aggregate size of concrete.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. Based on the nonlinear mesoscopic fracture theory, accurate anti-crack design of concrete in bridges, water conservancy and marine engineering is carried out. The tensile strength of concrete f tc can be regarded as the tensile strength f of the mortar tm Tensile strength increment Δf caused by bridging force with coarse aggregate t The superposition of the mortar f only requires a small-size specimen to obtain tm and aggregate ultimate bridging force F b It can carry out anti-cracking design of large-scale concrete.

[0031] 2. Considering the influence of the initial crack, the nominal strength increment Δσ at the crack tip caused by the coarse aggregate bridging force can be obtained according to the balance relationship of the critical state force. nm , Δσ is established nm and Δf t The relationship equation only requires the ultimate bridging force F of the aggregate to be determined experimentally. b 、Mortar tm And the shape function of the designed concrete specimen can determine the f of concrete specimens of various sizes and forms. tc ,

[0032] 3. The present invention only provides the stress form of internal aggregates when concrete is cracked. The external load that causes concrete cracking can be in any form, including but not limited to static loads such as three-point bending, four-point bending, axial tension, wedging splitting and hydraulic fracturing, dynamic loads and fatigue loads, etc.

[0033] 4. The present invention is applicable to medium, small and large-sized specimens without size effect; it is applicable to concrete prepared with coral aggregate, sea sand, recycled coarse and fine aggregates, etc.; it is applicable to shallow and deep cracked concrete specimens with a diameter of 0.1 to 0.5, it is simple to operate and can be widely used.

[0034] 5. The design value of tensile strength of marine aggregate concrete obtained by this design method is lower than the measured value, and the measured value is within the range of 95% assurance rate. Numerical simulation calculation can effectively avoid the risk of serious degradation of bearing capacity and service life caused by local cracking of concrete in bridges, water conservancy and marine engineering, and provide guarantee for the safety and reliability of practical engineering applications.

[0035] In summary, the anti-cracking calculation model of marine aggregate concrete constructed by the present invention is a method for determining macroscopic fracture parameters based on mesoscopic characteristics, which can be used through numerical simulation with finite element software. It is not only applicable to large-sized specimens, but also to small and medium-sized specimens; it is applicable to specimens with shallow and deep cracks; it is applicable to various marine load environments, avoiding the risk of serious degradation of bearing capacity and service life caused by concrete cracking in bridges, water conservancy and marine engineering, and has important engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Design flow chart for crack resistance;

[0037] Figure 2 is the stress distribution on the critical section when several point loads act on the crack surface;

[0038] Figure 3 Schematic diagram of coarse aggregate bridging mortar when local cracks occur in concrete;

[0039] Figure 4 Bond diagram for aggregate and mortar;

[0040] Figure 5 for Figure 4 The corresponding force-displacement diagram;

[0041] Figure 6 This is the crack expansion diagram in concrete;

[0042] Figure 7 is the stress distribution of the critical section of three-point bending;

[0043] Figure 8 A schematic diagram of normal distribution. DETAILED DESCRIPTION

[0044] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0045] A nonlinear anti-cracking model of marine aggregate concrete is designed based on the mesoscopic fracture theory. The tensile strength of concrete f tc Equal to the tensile strength f of the mortar tm Tensile strength increment Δf caused by bridging force with coarse aggregate t The sum includes the following steps:

[0046] S1. Modeling: Modeling marine aggregate concrete and marine mortar and marine aggregate constituting marine aggregate concrete respectively. After modeling, the marine aggregate concrete model is referred to as concrete, the marine mortar model is referred to as mortar, and the marine aggregate model is referred to as coarse aggregate.

[0047] S2. Calculate the tensile strength f of the mortar tm , the critical crack extension length of mortar The nominal strength increment of the cohesive force is assumed to be a constant and the mortar strength can be measured by small-size specimens.

[0048] The three-point bending test of the mortar with prefabricated cracks gave the value of F maxm and calculate the tensile strength f using the following formula tm ,

[0049] Three-point bending: ;

[0050] Equivalent cross-sectional area ;

[0051] , ,

[0052] In the formula, is the gravity of the mortar itself; F maxm is the maximum breaking load of mortar; is the mortar width; is the mortar height; is the support span; is the mortar joint height ratio, is the prefabricated seam length, is the average aggregate size of the mortar, is the discrete coefficient representing the discontinuous characteristics of the mortar,

[0053] S3. Calculate the tensile strength increment Δf caused by the bridging force of coarse aggregate t ,

[0054] Considering the influence of the initial crack, the nominal strength increment Δσ at the crack tip caused by the coarse aggregate bridging force can be obtained according to the equilibrium relationship of the critical state force: nm , Δσ is established nm and Δf t The relationship equation of

[0055] When the concrete reaches the maximum breaking load F maxc When the critical crack extension length The bridging effect of all coarse aggregates in the b , that is, the ultimate tensile strength or ultimate pull-out strength of the aggregate, can be measured by test.

[0056] The mortar is in an ideal linear elastic state and the effect of initial cracks is ignored. The applied load F b Corresponding nominal strength increment It can be expressed as ;

[0057] If the effect of initial cracks is considered in mortar, the external load F b Corresponding nominal strength increment It can be expressed as ;

[0058] Therefore, the influence factor of the initial crack is ;

[0059] Effective crack length ; In the formula, the shape function ;

[0060] Considering the effects of initial cracks and virtual cracks, the nominal strength increment can be obtained:

[0061] ;

[0062] Depend on It can be seen from the relationship that the tensile strength increment Δf caused by the bridging force of coarse aggregate t The calculation formula is:

[0063] ;

[0064] in, is the concrete width; is the concrete height; is the initial joint length of concrete; is the average aggregate size of concrete, is the discrete coefficient that represents the discontinuous characteristics of concrete; is the average aggregate size of the mortar, is the discrete coefficient representing the discontinuous characteristics of the mortar, and It is an empirical value, usually 1.5; is the effective crack length, the coefficient , and .

[0065] S4. According to Get the tensile strength of concrete f tc Predicted value.

[0066] Once cracks occur in concrete structures in bridges, water conservancy and marine engineering, the bearing capacity will decrease. This application aims to avoid local cracks through microscopic anti-crack design and numerical modeling, thereby improving the safety and reliability of the structure and extending the service life of the concrete structure.

[0067] The forms of external loads that cause concrete cracking in the present invention include, but are not limited to, static loads, dynamic loads, and fatigue loads.

[0068] The "marine aggregate concrete" mentioned in the present invention must contain at least two or more phases of media.

[0069] The "marine aggregate concrete" mentioned in the present invention is composed of coral aggregate, sea sand and recycled coarse and fine aggregates, and at least contains one of coral aggregate and sea sand, wherein the recycled coarse and fine aggregates are produced by the crushing of existing buildings demolished near the coast or on deep sea islands and reefs.

[0070] The present invention is applicable to medium, small and large sized specimens, i.e. / ≥8 concrete models without size effect, is the concrete height, is the average aggregate size of concrete.

[0071] The present invention is suitable for concrete with a joint height ratio of 0.1 to 0.5.

[0072] The slurry of the "marine aggregate concrete" mentioned in the present invention can be cement or alkali-activated material, and the mixing water can be fresh water or sea water.

[0073] The main idea of ​​the present invention is that it is found through research that the tensile strength increment of concrete from the cracking load to the ultimate load is mainly provided by the bridging force of the coarse aggregate. Based on this, the tensile strength of the concrete can be obtained by superimposing the tensile strength of the mortar and the tensile strength increment caused by the bridging force of the coarse aggregate. Considering the influence of the initial crack, the nominal strength increment Δσ at the crack tip caused by the bridging force of the coarse aggregate can be obtained according to the balance relationship of the critical state force. nm , Δσ is established nm and Δf t The relationship equation is: b 、Mortar tm And the shape function of the designed concrete specimen can determine the f of concrete specimens of various sizes and forms. tc .

[0074] In the embodiment, the concrete tensile strength prediction value is first calculated using the design method of the present application. , and then through the simulation calculation of multiple sets of predicted values Take the average value μ fand standard deviation σ f , and calculate the interval μ with 95% assurance rate f ±2σ f Finally, the measured value of concrete tensile strength obtained by three-point bending test was compared with the actual value. The following Examples 1-4 verify that the design value of the tensile strength of marine aggregate concrete obtained by this design method is lower than the measured value, and the measured value is within the range of 95% guarantee rate, which provides a guarantee for the safety and reliability of practical engineering applications.

[0075] The present invention is further described in detail below through specific examples and comparative examples.

[0076] Embodiment 1: The method for designing crack resistance of marine aggregate concrete based on mesoscopic fracture theory, wherein the specimen preparation method is as follows: firstly, a 40mm×40mm×160mm seawater and sea sand mortar specimen, a 20mm×20mm×20mm coral aggregate cube specimen, and a 100mm×100mm×515mm concrete prism specimen prepared with coral coarse aggregate, sea sand and seawater are prepared, and the specimens are placed in an environment of 20°C±5°C, and the molds are removed after standing for 1 day, and then the specimens are cured to a specified age in an environment of 20°C±2°C and a relative humidity of more than 95%. The cured specimens are cut along the height direction, and the seam height ratios are 0.1, 0.2, 0.3, 0.4 and 0.5 respectively, and 5 groups of specimens are prepared for each seam height ratio, and the test specimens are used. Figure 1-6 The method shown is used for crack resistance design.

[0077] Anti-cracking design method of marine aggregate concrete based on mesoscopic fracture theory:

[0078] The mortar and concrete specimens were subjected to three-point bending tests at a loading rate of 0.2 mm / min to determine the tensile strength, and the aggregate specimens were subjected to axial tension at a loading rate of 0.2 mm / min to determine the ultimate load F. b .

[0079] After testing, this embodiment β m =β c =1.5, d m =3mm, d c =6mm.

[0080] 1. Tensile strength of mortar :

[0081] Take mortar =40mm, =40mm, =160mm, =20.38N, =402.09N, =12mm is used to illustrate the tensile strength calculation example. The calculation process is as follows:

[0082] ① =0.3;

[0083] ② ;

[0084] ③Equivalent cross-sectional area ;

[0085] ④ .

[0086] 2. Tensile strength increment caused by coarse aggregate and predicted tensile strength of concrete :

[0087] Take the aggregate F b =353.67N, design size =100mm, =100mm, =30mm concrete tensile strength prediction example, the calculation process is as follows:

[0088] ① , and ;

[0089] ② ;

[0090] ③Effective crack length ;

[0091] ④ ;

[0092] ⑤ .

[0093] Comparison verification group: measured value of tensile strength of concrete :

[0094] The force balance of the concrete specimen under three-point bending is as follows: Figure 7 As shown, the measured value of the tensile strength of concrete The calculation method is carried out using the following method:

[0095] Three-point bending: ;

[0096] Equivalent cross-sectional area ;

[0097] Shape Function (Applicable conditions / =4);

[0098] In the formula, is the concrete's own gravity, is the maximum breaking load, is the concrete width, is the concrete height, is the support span; is the initial joint length of concrete, is the seam height ratio; is the average aggregate size of concrete, It is the discrete coefficient that represents the discontinuous characteristics of concrete.

[0099] Pick =100mm, =100mm, =400mm, =115.05N, = 2660.55N of concrete, =30mm is used to calculate the actual measured value of concrete. The calculation process is as follows:

[0100] ① ;

[0101] ② ;

[0102] ③Equivalent cross-sectional area ;

[0103] ④ .

[0104] In this embodiment, in F b =100~450N, =10~50mm, Δf t =0.089~0.561MPa; Figure 8 The normal distribution shown predicts the mean value of the tensile strength μ f is 2.999MPa, standard deviation σ f is 0.27MPa, and the interval with 95% guarantee rate is μ f ±2σ f =2.459~3.539MPa; measured value of 25 groups of concrete prepared It is 3.152MPa, and the crack resistance design value is 2.459MPa.

[0105] Example 2: The specimen preparation method is as follows: prepare a 40mm×40mm×160mm seawater recycled mortar specimen, a 20mm×20mm×20mm coral aggregate cube specimen, and a 100mm×100mm×515mm concrete prism specimen prepared with coral coarse aggregate, recycled fine aggregate and seawater.

[0106] The anti-cracking design method and test method of marine aggregate concrete based on microscopic fracture theory are the same as those in Example 1; the measured value of the tensile strength of concrete is The calculation method is the same as that of the comparison verification group in Comparative Example 1.

[0107] After testing, this embodiment =100mm, =100mm, β m =β c =1.5, d m =3mm, d c =6mm, f tm =2.24MPa. b =100~450N, =10~50mm, Δf t =0.089~0.561MPa; the average value of tensile strength predicted by normal distribution μ f is 2.617MPa, standard deviation σ f is 0.33MPa, and the interval with 95% guarantee rate is μ f ±2σ f =1.957~3.277MPa; measured values ​​of 25 groups of concrete prepared It is 2.486MPa, and the design value for crack resistance is 1.957MPa.

[0108] Example 3: The specimen preparation method is as follows: prepare 40mm×40mm×160mm freshwater sea sand mortar specimens, 20mm×20mm×20mm coral aggregate cube specimens and 100mm×100mm×515mm concrete prism specimens prepared with coral coarse aggregate, sea sand and fresh water.

[0109] The anti-cracking design method and test method of marine aggregate concrete based on microscopic fracture theory are the same as those in Example 1; the measured value of the tensile strength of concrete is The calculation method is the same as that of the comparison verification group in Comparative Example 1.

[0110] After testing, this embodiment =100mm, =100mm, β m =β c =1.5, d m =3mm, d c =6mm, f tm =2.65MPa. b =100~450N, =10~50mm, Δf t=0.089~0.561MPa; the average value of tensile strength predicted by normal distribution μ f is 2.949MPa, standard deviation σ f is 0.27MPa, and the interval with 95% guarantee rate is μ f ±2σ f =2.409~3.489MPa; measured values ​​of 25 groups of concrete prepared It is 3.084MPa, and the crack resistance design value is 2.409MPa.

[0111] Example 4: The specimen preparation method is as follows: prepare 40mm×40mm×160mm seawater and sea sand mortar specimens, 20mm×20mm×20mm recycled aggregate cube specimens and 100mm×100mm×515mm concrete prism specimens prepared with recycled coarse aggregate, sea sand and seawater.

[0112] The anti-cracking design method and test method of marine aggregate concrete based on microscopic fracture theory are the same as those in Example 1; the measured value of the tensile strength of concrete is The calculation method is the same as that of the comparison verification group in Comparative Example 1.

[0113] After testing, this embodiment =100mm, =100mm, β m =β c =1.5, d m =3mm, d c =6mm, f tm =2.7Mpa. b =240~500N, =10~50mm, Δf t =0.214~0.623MPa; the average value of tensile strength predicted by normal distribution μ f is 3.154MPa, standard deviation σ f is 0.24MPa, and the interval with 95% guarantee rate is μ f ±2σ f =2.674~3.634MPa; measured value of 25 groups of concrete prepared It is 3.303MPa, and the crack resistance design value is 2.674MPa.

[0114] The predicted values, measured values ​​and designed values ​​of Examples 1-4 are shown in Table 1.

[0115] Table 1 Summary of predicted values, measured values ​​and designed values ​​of Examples 1-4

[0116]

[0117] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit and scope of the present application, appropriate changes and modifications to the above embodiments are within the scope of protection claimed in the present application.

Claims

1. A method for anti-cracking design of marine aggregate concrete based on mesoscopic fracture theory, characterized in that: A nonlinear anti-cracking model of marine aggregate concrete is designed based on the mesoscopic fracture theory. The tensile strength of concrete f tc Equal to the tensile strength f of the mortar tc Tensile strength increment Δf caused by bridging force with coarse aggregate t The sum includes the following steps: S1. Modeling: Modeling marine aggregate concrete and marine mortar and marine aggregate constituting marine aggregate concrete respectively. After modeling, the marine aggregate concrete model is referred to as concrete, the marine mortar model is referred to as mortar, and the marine aggregate model is referred to as coarse aggregate. S2. Calculate the tensile strength f of the mortar tc , The three-point bending test of the mortar with prefabricated cracks gave F maxm and calculate the tensile strength f using the following formula tc , Three-point bending: Equivalent cross-sectional area In the formula, is the gravity of the mortar itself; F maxm is the maximum breaking load; is the mortar width; is the mortar height; L m is the support span; is the mortar joint height ratio, is the length of the mortar prefabricated joint, d m is the average aggregate size of the mortar, β m is the discrete coefficient representing the discontinuous characteristics of the mortar; S3. Calculate the tensile strength increment Δf caused by the bridging force of coarse aggregate t , When the concrete reaches the maximum breaking load F maxc When the critical crack extension length β c d c The bridging effect of all coarse aggregates in the b , that is, the ultimate tensile strength or ultimate pull-out strength of the aggregate. The ultimate load is determined by axial tension of the aggregate specimen; the critical crack extension length β of the mortar m d m The nominal strength increment of the cohesive force is assumed to be a constant; considering the effect of the initial crack and the virtual crack, the nominal strength increment can be obtained Depend on It can be seen from the relationship that the tensile strength increment Δf caused by the bridging force of coarse aggregate t The calculation formula is in, is the concrete width; h c is the concrete height; is the initial joint length of concrete; is the average aggregate size of concrete, β c is the discrete coefficient representing the discontinuous characteristics of concrete; d m is the average aggregate size of the mortar, β m is the discrete coefficient representing the discontinuous characteristics of the mortar, is the effective crack length, Effective crack length In the formula, the coefficient Seam height ratio Shape Function S4, according to f tc =f tm -Δf t Get the tensile strength of concrete f tc Predicted value.

2. The method for anti-cracking design of marine aggregate concrete based on mesoscopic fracture theory according to claim 1 is characterized in that: The joint height ratio of concrete is 0.1~0.

5.

3. The method for anti-cracking design of marine aggregate concrete based on mesoscopic fracture theory according to claim 1 is characterized in that: The predicted value range of tensile strength with 95% assurance rate is predicted by normal distribution, and the lower limit of the predicted value of tensile strength with 95% assurance rate is used as the design value of concrete crack resistance.

4. The method for anti-cracking design of marine aggregate concrete based on mesoscopic fracture theory according to any one of claims 1 to 3, characterized in that: The concrete in the method contains at least two or more phases of media, and the method is applicable to but not limited to concrete prepared with coral aggregate, sea sand and recycled coarse and fine aggregates.

5. The method for anti-cracking design of marine aggregate concrete based on mesoscopic fracture theory according to any one of claims 1 to 3, characterized in that: The forms of external loads that cause concrete cracking include but are not limited to static loads, dynamic loads and fatigue loads.

6. The method for anti-cracking design of marine aggregate concrete based on mesoscopic fracture theory according to any one of claims 1 to 3, characterized in that: Applicable to h c / d c Concrete model ≥8, h c is the concrete height, d c is the average aggregate size of concrete.

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