Prediction model of multi-stage loading cumulative plastic strain based on MICP improved construction waste, model construction method and prediction method

Abstract

The invention relates to a multi-stage loading cumulative plastic strain prediction model based on MICP improved construction waste, a model construction method and a prediction method. On the basis of a test result of multi-stage loading cumulative plastic strain, a cumulative plastic strain prediction model which comprehensively considers factors such as calcium ion concentration, maintenance time, dynamic stress, matrix suction and loading times is established. According to the model, the strain evolution process of the construction waste under different working conditions is effectively described by introducing the coupling effect of multiple factors, so that the long-term deformation characteristic of the material is accurately predicted. A multi-stage loading cumulative plastic strain prediction model is established, and the method has important significance on performance evaluation and application optimization of engineering materials under different stress conditions. Through the prediction model, the mechanical performance of the construction waste can be evaluated in advance, reasonable selection of materials in different application scenes is guided, and long-term safety and stability of the structure are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling of waste building materials, and relates to a prediction model of multi-stage loading cumulative plastic strain of building waste based on MICP improvement, a model construction method and a prediction method. Background Art

[0002] In the process of improving construction waste with MICP technology, it is essential to conduct multi-stage loading cumulative plastic strain tests to fully understand its mechanical behavior under different load conditions. Construction waste needs to withstand various forms of external loads in actual engineering, including repeated dynamic loads and long-term static loads, and these loads are crucial to the accumulation of internal strain and plastic deformation of the material. Traditional single-load mechanical test methods are usually difficult to fully reflect the cumulative strain changes of materials under repeated loading and their final mechanical properties. By studying the deformation characteristics of MICP-modified construction waste through multi-stage loading cumulative plastic strain tests, we can systematically reveal the law of its performance evolution under long-term multiple loading conditions, thereby evaluating its stability and reliability under complex load conditions. This is not only of great significance for understanding the performance evolution law of MICP-modified construction waste, but also provides a scientific basis for further optimizing the application process of MICP modification technology.

[0003] In order to better realize the application of MICP-modified construction waste in engineering and ensure its stable performance under long-term load, it is particularly necessary to establish a prediction model based on multi-stage loading cumulative plastic strain. The stress conditions of construction waste in actual engineering applications are complex. The evolution of cumulative plastic strain is not only closely related to the number of loading times, but also affected by multiple factors such as calcium ion concentration, curing time, dynamic stress and matrix suction. These factors are coupled with each other, resulting in the strain behavior of the material being highly nonlinear and complex. Therefore, establishing a prediction model for multi-stage loading cumulative plastic strain not only helps to effectively predict the deformation trend of the material under multiple loading conditions, but also provides a scientific basis and technical support for the application design of MICP-modified construction waste in actual engineering. Through this prediction model, the quantitative evaluation of the modification effect of construction waste can be achieved, thereby guiding its rational application in different engineering scenarios and ensuring the long-term performance and structural safety of the material.

[0004] In summary, the research on MICP technology to modify construction waste has important engineering value and practical significance in the current context. By studying the cumulative plastic strain of construction waste under multi-level loading, the deformation law of MICP modification effect under different working conditions can be fully revealed, and the establishment of the corresponding cumulative plastic strain prediction model provides important theoretical support and technical guidance for practical engineering applications. This research not only provides a technical basis for the resource utilization of construction waste, but also has a positive role in promoting the green environmental protection and sustainable development of building materials. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a prediction model of multi-stage loading cumulative plastic strain of construction waste based on MICP improvement, and the model is:

[0006]

[0007] Where:

[0008] C Ca 2+ is the calcium ion concentration; D m is the maintenance days; d is the dynamic loading stress; N is the number of cyclic loading; is the standard calcium ion concentration, which is 1 mol / L; e is a mathematical constant, which is 2.718; P a is the atmospheric pressure, which is 100 kPa; is the matrix suction when water content = i; is the matrix suction when the water content is OMC; a, n, and m are the parameters of the VAN-GENUCHTEN model; a 1 、a 2 , b 1 , b 2 , b 3 , b 4 , b 5 , b 6 , b 7 is the model parameter.

[0009] This application also provides a method for constructing a model, the specific steps are as follows:

[0010] Step (1) selecting construction waste materials for crushing and screening, and conducting a system basic physical property test; based on the above basic physical property test, measuring the soil-water characteristic curve of the construction waste and determining the water absorption characteristics of the construction waste under different water content states;

[0011] Step (2) adding equal volumes of MICP improvement reaction solution of different concentrations into the sample and mixing thoroughly;

[0012] Step (3) forming the sample prepared in step (2) into a cylindrical sample and compacting it, and then curing it under different time conditions;

[0013] Step (4) Dynamic triaxial test

[0014] The multi-stage loading cumulative plastic strain test method was adopted, and a total of 4 stress levels were designed for the multi-stage loading permanent deformation test; thus, the multi-stage loading cumulative plastic strain test results under different conditions were obtained;

[0015] Step (5) Based on the results of steps (1) and (4), construct a comprehensive consideration of C Ca 2+ , D m , σ d , ω, N multi-level loading cumulative plastic strain prediction model;

[0016] The model is:

[0017]

[0018] Where:

[0019] C Ca 2+ is the calcium ion concentration; D m is the maintenance days; d is the dynamic loading stress; N is the number of cyclic loading; is the standard calcium ion concentration, which is 1 mol / L; e is a mathematical constant, which is 2.718; P a is the atmospheric pressure, which is 100 kPa; is the matrix suction when water content = i; is the matrix suction when the water content is OMC; a, n, and m are the parameters of the VAN-GENUCHTEN model; a 1 、a 2 , b 1 , b 2 , b 3 , b 4 , b 5 , b 6 , b 7 is the model parameter.

[0020] On the basis of the above scheme, the VAN-GENUCHTEN model is used to determine the water absorption characteristics of construction waste under different water content states in step (1).

[0021] Based on the above scheme, in step (2), C in the reaction solution Ca 2+The concentrations were set to 0 mol / L, 0.5 mol / L, 1 mol / L and 2 mol / L, and the bacteria used in the reaction solution was Sporosarcina pasteurianus.

[0022] On the basis of the above scheme, in step (4), during the test, the confining pressure is set to 30 kPa, the dynamic loading stress is set to 15 kPa, 30 kPa, 45 kPa, and 60 kPa respectively, the number of loadings at each level is 10,000 times, the loading frequency is 1 Hz, the loading time is 0.1 s, and the interval time is 0.9 s.

[0023] The present application also provides a method for predicting the cumulative plastic strain of multi-stage loading of construction waste based on MICP improvement, using the above-mentioned model.

[0024] Based on the test results of multi-stage loading cumulative plastic strain, the present invention establishes a cumulative plastic strain prediction model that comprehensively considers factors such as calcium ion concentration, curing time, dynamic stress, matrix suction and loading times. The model effectively describes the strain evolution process of construction waste under different working conditions by introducing the coupling effect of multiple factors, thereby realizing accurate prediction of the long-term deformation characteristics of the material. The composition of construction waste is complex, and the performance differences are large. Its stress state has high complexity and nonlinear characteristics under actual working conditions. Therefore, the establishment of a multi-stage loading cumulative plastic strain prediction model is of great significance for the performance evaluation and application optimization of engineering materials under different stress conditions. Through this prediction model, the mechanical properties of construction waste can be evaluated in advance, the rational selection of materials in different application scenarios can be guided, and the long-term safety and stability of the structure can be ensured, thereby realizing efficient, green and sustainable utilization of construction waste.

[0025] The present invention improves construction waste by applying MICP technology, which not only significantly improves the mechanical properties and stability of the material, but also comprehensively reveals the strain evolution law of the modified material under complex load conditions through multi-level loading cumulative plastic strain test and the establishment of a prediction model, and provides a scientific basis and technical guidance for its application in practical engineering. The invention provides an innovative solution for the resource utilization of construction waste, has significant social, economic and environmental value, and meets the technical requirements for sustainable development in the field of modern civil engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1The results of the screening test of construction waste in Example 2;

[0028] Figure 2 The results of the filter paper method for construction waste;

[0029] Figure 3 C Ca 2+ =0mol / L, D m =0,σ 3 =30kPa, the results of multi-level loading cumulative plastic strain tests corresponding to different ω (0.9OMC, OMC, 1.1OMC);

[0030] Figure 4 ω=OMC,D m =0,6,σ 3 =30kPa, different C Ca 2+ (0mol / L, 0.5mol / L, 1mol / L and 2mol / L) corresponding multi-level loading cumulative plastic strain test results;

[0031] Figure 5 C Ca 2+ =0, 1 mol / L, ω = OMC, σ 3 =30kPa, different D m (0, 1, 3, 6, 10) corresponding to the multi-level loading cumulative plastic strain test results;

[0032] Figure 6 Robustness verification diagram of the newly built model; DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] The present invention provides a prediction model for the cumulative plastic strain of multi-stage loading of construction waste based on MICP improvement, and the model is:

[0036]

[0037] Where:

[0038] C Ca 2+ is the calcium ion concentration; Dm is the maintenance days; d is the dynamic loading stress; N is the number of cyclic loading; is the standard calcium ion concentration, which is 1 mol / L; e is a mathematical constant, which is 2.718; P a is the atmospheric pressure, which is 100 kPa; is the matrix suction when water content = i; is the matrix suction when the water content is OMC; a, n, and m are the parameters of the VAN-GENUCHTEN model; a 1 、a 2 , b 1 , b 2 , b 3 , b 4 , b 5 , b 6 , b 7 is the model parameter.

[0039] The construction method of the above model is:

[0040] Step (1) selecting construction waste materials for crushing and screening, and conducting a system basic physical property test; based on the above basic physical property test, the soil-water characteristic curve of the construction waste is measured and the VAN-GENUCHTEN model is used to determine the water absorption characteristics of the construction waste under different water content states;

[0041] Step (2) adding equal volumes of MICP improvement reaction solutions of different concentrations to the sample and mixing thoroughly; C in the reaction solution Ca 2+ The concentrations were set to 0 mol / L, 0.5 mol / L, 1 mol / L and 2 mol / L, and the bacteria used in the reaction solution was Sporosarcina pasteurianus.

[0042] Step (3) forming the sample prepared in step (2) into a cylindrical sample and compacting it, and then curing it under different time conditions;

[0043] Step (4) Dynamic triaxial test

[0044] A multi-stage loading cumulative plastic strain test method was adopted, and a total of 4 stress levels were designed for the multi-stage loading permanent deformation test; then the multi-stage loading cumulative plastic strain test results under different conditions were obtained; during the test, the confining pressure was set to 30 kPa, and the dynamic loading stresses were set to 15 kPa, 30 kPa, 45 kPa, and 60 kPa respectively, the number of loadings at each level was 10,000 times, the loading frequency was 1 Hz, the loading time was 0.1 s, and the interval time was 0.9 s.

[0045] Step (5) Based on the results of steps (1) and (4), construct a comprehensive consideration of C Ca 2+ , D m , σ d Multi-level loading cumulative plastic strain prediction model for , ω, and N.

[0046] Example 2

[0047] The embodiment of the present invention provides a method for predicting the multi-stage loading cumulative plastic strain of construction waste using MICP technology. The specific process is as follows:

[0048] Step a: The construction waste materials selected in this embodiment come from demolition waste from a construction site in Changsha City, and are crushed and screened to ensure that they meet the test requirements. The main components of the waste include concrete, masonry and mortar blocks, with corresponding mass proportions of 45.2%, 15.3% and 39.5% respectively. The particle gradation curve of the material is as follows: Figure 1 In order to gain a deeper understanding of the basic physical characteristics of these construction wastes, a systematic physical performance test was conducted.

[0049] The test results show that the organic matter content of the construction waste is 1.9%, the soluble salt content is 0.38%, and the content of other impurities is 0.9%. These indicators show that there are a small amount of organic impurities and soluble salts in the material, which may affect its durability and stability in actual engineering. In addition, the liquid limit and plastic limit of the material are 28% and 22% respectively, which indicates that it has a certain plasticity but not significant, and may show limited deformation ability when sheared. The maximum dry density of the material is 1.84g / cm 3 The optimum moisture content (OMC) is 14.8%, indicating that the best compaction effect can be achieved under this moisture content.

[0050] Based on the above research on basic physical properties, the filter paper method that complies with the ASTM D5298-10 specification was selected to measure the soil-water characteristic curve (SWCC) of construction waste.

[0051] The filter paper method is a commonly used and effective method for measuring matrix suction. It is suitable for testing various types of soils and fillers, and has the characteristics of simple operation and wide measurement range. In order to further quantify the water absorption characteristics of construction waste under different water content states, this embodiment uses the VAN-GENUCHTEN model to fit and describe its soil-water characteristic curve. This model is a typical unsaturated soil characteristic model that can accurately fit the water absorption characteristics of construction waste. The fitting results are shown in Figure 2. Figure 2 shown.

[0052] Step b: Based on the reaction mechanism of MICP, the reaction solution consists of bacterial solution and cementing solution. Its basic reaction equation is shown in formulas (1) to (3):

[0053]

[0054] Ca 2+ +Cell——→Cell-Ca 2+ (2)

[0055] Cell-Ca 2+ +CO 3 2- ——→Cell-CaCO 3 ↓ (3)

[0056] In an alkaline environment, bacteria secrete urease through metabolic activities, which can continuously catalyze the hydrolysis of urea to produce ammonium ions (NH 4 + ) and carbonate ions (CO 3 2- ), as shown in formula (1). At the same time, since the bacterial cell surface has a negative charge, it can attract calcium ions (Ca 2+ ), and then combined with carbonate ions to form calcium carbonate crystals with cementing effect, as described in formulas (2) and (3). In this process, bacteria are not only responsible for the production of urease and the hydrolysis of urea, but also serve as the core attachment point for calcium carbonate precipitation. It can be seen that culturing highly active bacterial liquid is a key step in implementing MICP technology.

[0057] To this end, the present invention selected Sporosarcina pasteurii (CGMCC 1.3687), which is environmentally friendly and non-toxic, as the strain. In order to achieve the activation and large-scale cultivation of the strain, the present invention selected NH 4 -YE liquid medium, specifically including 21g / L yeast extract, 9g / L ammonium chloride (NH 4 Cl), 23mg / L nickel chloride hexahydrate (NiCl 2 6H 2 O), 11mg / L manganese sulfate tetrahydrate (MnSO 4 ·4H 2 O) and 1L pure water. These ingredients provide sufficient nutrition for bacteria, especially nitrogen source and trace elements, to promote the rapid growth of bacteria and the ability to secrete urease.

[0058] After the preparation of the culture medium, it is divided into sterilized containers and sterilized by high-pressure steam at 121°C for 20 minutes to ensure the sterility of the culture medium environment and avoid the influence of contamination on the culture of bacteria. After the sterilized culture medium is cooled to room temperature, the activated bacteria are aseptically inoculated at a ratio of 1:100. The inoculated bacterial solution is placed in a constant temperature shaking incubator and cultured continuously for 20 hours at 30°C and 150r / min to obtain sufficient quantity and high activity of bacteria.

[0059] After the bacterial culture was completed, the optical density (OD) of the bacterial solution was measured using a TU-1950 UV-visible spectrophotometer. 600 ), used to evaluate the growth concentration of the bacterial solution. In this experiment, the OD 600 The value was 3.0, indicating that the bacterial growth concentration was high and the activity was good. At the same time, the urease activity of the bacterial solution was measured using a DDS-11A conductivity meter. The urease activity was calculated based on the empirical formula of Whiffin et al., converting the change in conductivity into the amount of urea hydrolyzed per unit time. In this experiment, the measured urease activity was 15.4 μmol urea hydrolyzed per minute, showing a high biocatalytic ability.

[0060] In addition, in order to ensure the effective precipitation of calcium carbonate during the MICP process, this experiment selected calcium chloride (CaCl 2 ) and urea. 2 As a calcium source, it provides sufficient calcium ions (Ca 2+ ); Urea not only provides a nitrogen source during bacterial metabolism, but also hydrolyzes under the action of urease to produce carbonate ions, which combine with calcium ions to form calcium carbonate precipitation. This process plays an important role in the cementation and reinforcement of porous media, effectively improving the strength and stability of the media.

[0061] Step c:

[0062] (a) MICP treatment of construction waste

[0063] The optimal moisture content of the sample is determined by the compaction test results, and the MICP reaction solution is prepared according to the above steps. Ca 2+ Set to 0 mol / L, 0.5 mol / L, 1 mol / L and 2 mol / L. Add equal volumes of the prepared reaction solution (same volume of 0.9 OMC, OMC, 1.1 OMC) to the sample and stir thoroughly to ensure that the microorganisms and Ca 2+ Uniform contact between particles.

[0064] (b) Sample preparation and curing

[0065] Cylindrical specimens with a diameter of 101 mm and a height of 200 mm were prepared using a standard split mold, and compacted to 95% of the maximum dry density of the specimen as determined by the compaction test results. Then, to ensure the effectiveness of the MICP treatment, the specimens were immediately placed in a constant temperature and humidity curing chamber (the curing temperature was set at 25°C) after preparation. m Effect of MICP treatment on the m The settings for increasing the backward difference are 0, 1, 3, 6, and 10 days.

[0066] (c) Formulate dynamic triaxial test plan

[0067] In the traditional single-stage dynamic triaxial test, each specimen only considers a single stress loading mode, that is, only one confining pressure and one level of dynamic loading stress can be loaded each time. If the multi-level dynamic loading stress in the actual project is to be simulated, a large number of specimens need to be made, which is not only time-consuming and labor-intensive, but also costly, and does not conform to the continuous loading stress state actually suffered by the roadbed, and also fails to reflect the actual situation of increasing axle weight. For this reason, the present invention designs a multi-stage loading cumulative plastic strain test method, considering that the cumulative strain caused by the smaller stress in the early stage has little effect on the cumulative strain caused by the larger stress in the later stage, but the larger amplitude dynamic load will change the cumulative strain caused by the subsequent small stress, and the multi-stage loading permanent deformation test is designed with 4 levels of stress levels. Among them, the confining pressure is set to 30kPa, and the dynamic loading stress is set to 15kPa, 30kPa, 45kPa, and 60kPa respectively according to the stress ratio (0.5, 1, 1.5, 2). The number of loadings at each level is 10,000 times, the loading frequency is 1Hz, the loading time is 0.1s, and the interval time is 0.9s.

[0068] (4) Analysis of dynamic triaxial test results

[0069] Without MICP treatment (C Ca 2+ =0mol / L, D m =0), in σ 3 =30kPa and different ω (0.9OMC, OMC, 1.1OMC) multi-stage loading cumulative plastic strain test results are shown in Figure 3 As shown. Different C Ca 2+ (0mol / L, 0.5mol / L, 1mol / L and 2mol / L) solid waste samples, at ω=OMC, σ 3 =30kPa and D m =0,6(C Ca 2+ =0mol / L, D m =0) under multi-stage loading cumulative plastic strain test conditions. Figure 4 As shown. Different D m (0, 1, 3, 6, 10) solid waste samples, at ω = OMC, σ 3 =30kPa and C Ca 2+ =0,1mol / L(D m =0, C Ca 2+ =0mol / L) under the condition of multi-stage loading cumulative plastic strain test results are as follows Figure 5 shown.

[0070] Step d:

[0071] The present invention is based on the multi-stage loading cumulative plastic strain test results shown in the previous step ( Figure 3 to Figure 5 ), establish comprehensive consideration C Ca 2+ , D m , σ d The multi-stage loading cumulative plastic strain prediction model of , ω, and N is established in the following steps as shown in formulas (4) to (8), and the model parameters are shown in Table 1:

[0072] ① First, a basic prediction model for the cumulative plastic strain of multi-level loading is established, which includes comprehensive consideration of C Ca 2+ , D m , σ d , the f function of ω and the independent term considering the number of cyclic loading times N, as shown in formula (4):

[0073]

[0074] ②Basis Figure 3 to Figure 5 The test results shown show that C Ca 2+ , D m , σ d The influence of ω and the cumulative plastic strain of multi-level loading is studied, and the specific expression of the f function is established based on the principle of coupling of influencing factors and dimensional unification, as shown in formula (5):

[0075]

[0076] ③ In the study of soil mechanics and MICP modified materials, matrix suction is a key factor affecting material strain and strength. In order to further accurately describe the variation of matrix suction under different conditions, the present invention uses the VAN-GENUCHTEN model to derive it. Assuming that the porosity remains unchanged, the calculation expressions of water content and matrix suction are shown in formulas (6) to (7):

[0077]

[0078] ④Combination Figure 2 The final expression of the multi-level loading cumulative plastic strain prediction model can be obtained by combining formulas (4) to (7), as shown in formula (8):

[0079]

[0080] Where: is the accumulated plastic strain; C Ca 2+ is the calcium ion concentration; D m is the maintenance days; d is the dynamic loading stress; ω is the water content; N is the number of cyclic loading; is the standard calcium ion concentration, which is 1 mol / L; e is a mathematical constant, which is 2.718; P a is the atmospheric pressure, which is 100 kPa; ω i is the actual moisture content; ω omc is the optimum moisture content; S r-i is the saturation corresponding to the actual water content; S r-omc is the saturation corresponding to the optimal water content; S r-r is the residual saturation; is matrix suction; is the matrix suction when water content = i; is the matrix suction when the water content is OMC; a, n, and m are the VAN-GENUCHTEN model parameters (the three model parameters are obtained by Figure 2 The results of the filter paper method were calculated using the VG model combined with the least squares method. ), and their values ​​were a=0.23, n=24.68, m=0.01; a 1 、a 2 , b 1 , b 2 , b 3 , b 4 , b 5 , b 6 , b 7 is the model parameter.

[0081] Table 1 Statistics of estimated model parameters

[0082]

[0083] In addition, in order to determine the applicability of the MICP technology proposed in the present invention to improve the prediction method of the cumulative plastic strain of multi-stage loading of construction waste, the robustness of the new model of the present invention, formula (8), is verified. The measured value of the cumulative plastic strain is the horizontal axis, and the predicted value is the vertical axis, and then a robustness verification scatter plot is drawn. The results are as follows: Figure 6 As shown in Figure 2, it can be seen that most of the scattered points are concentrated around the straight line y=x, R 2 =0.96, RMSE =0.04, and the fitting effect is good. Therefore, the cumulative plastic strain obtained by the new model under multi-level loading is highly representative and meets the needs of engineering.

[0084] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A prediction model for the cumulative plastic strain of multi-stage loading of construction waste based on MICP, characterized in that: The model is: Where: C Ca 2+ is the calcium ion concentration; D m is the maintenance days; d is the dynamic loading stress; N is the number of cyclic loading; is the standard calcium ion concentration, which is 1 mol / L; e is a mathematical constant, which is 2.718; P a is the atmospheric pressure, which is 100 kPa; is the matrix suction when water content = i; is the matrix suction when the water content is OMC; a, n, m are the parameters of the VAN-GENUCHTEN model; a1, a2, b1, b2, b3, b4, b5, b6, and b7 are model parameters.

2. A method for constructing the model of claim 1, characterized in that: The specific steps are as follows: Step (1) selecting construction waste materials for crushing and screening, and conducting a system basic physical property test; based on the above basic physical property test, measuring the soil-water characteristic curve of the construction waste and determining the water absorption characteristics of the construction waste under different water content states; Step (2) adding equal volumes of MICP improvement reaction solution of different concentrations into the sample and mixing thoroughly; Step (3) forming the sample prepared in step (2) into a cylindrical sample and compacting it, and then curing it under different time conditions; Step (4) Dynamic triaxial test The multi-stage loading cumulative plastic strain test method was adopted, and a total of 4 stress levels were designed for the multi-stage loading permanent deformation test; thus, the multi-stage loading cumulative plastic strain test results under different conditions were obtained; Step (5) Based on the results of steps (1) and (4), construct a comprehensive consideration of C Ca 2+ , D m , σ d , ω, N multi-level loading cumulative plastic strain prediction model; The model is: Where: C Ca 2+ is the calcium ion concentration; D m is the maintenance days; d is the dynamic loading stress; N is the number of cyclic loading; is the standard calcium ion concentration, which is 1 mol / L; e is a mathematical constant, which is 2.718; P a is the atmospheric pressure, which is 100 kPa; is the matrix suction when water content = i; is the matrix suction when the water content is OMC; a, n, m are the parameters of the VAN-GENUCHTEN model; a1, a2, b1, b2, b3, b4, b5, b6, and b7 are model parameters.

3. The method for constructing a model according to claim 2, characterized in that: In step (1), the VAN-GENUCHTEN model is used to determine the water absorption characteristics of construction waste under different water content states.

4. The method for constructing a model according to claim 2, characterized in that: In step (2), C in the reaction solution Ca 2+ The concentrations were set to 0 mol / L, 0.5 mol / L, 1 mol / L and 2 mol / L, and the bacteria used in the reaction solution was Sporosarcina pasteurianus.

5. The method for constructing a model according to claim 2, characterized in that: In step (4), during the test, the confining pressure is set to 30 kPa, the dynamic loading stress is set to 15 kPa, 30 kPa, 45 kPa, and 60 kPa respectively, the number of loadings at each level is 10,000 times, the loading frequency is 1 Hz, the loading time is 0.1 s, and the interval time is 0.9 s.

6. The model constructed by the method according to any one of claims 2 to 5.

7. A prediction method for the cumulative plastic strain of multi-stage loading of construction waste based on MICP, characterized in that: Use the model of claim 1 or 6.

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