A testing and evaluation method for the degradation performance of degradable straw drainage boards

Abstract

The present invention discloses a method for testing and evaluating the degradation performance of degradable straw drainage boards. Through soil burial in a constant temperature, constant humidity, and low-light environment in an engineering soil environment, after biodegradation for a specific time, the samples are removed, and then tensile, weight loss rate, and drainage performance tests are carried out. The analytic hierarchy process is used to determine the weights of various factors, and a new evaluation method for obtaining the degradation rate is comprehensively evaluated, so as to propose a material degradation evaluation method more suitable for the geotechnical engineering field, redefine the engineering service life of degradable straw drainage board materials by integrating three-party factors, and avoid engineering risks brought by single evaluation index evaluation. The present invention is accurate and efficient, does not require expensive instrument equipment, and is easy to be popularized and applied in enterprises and third-party laboratories.

Description

Technical Field

[0001] The present invention relates to the fields of environmental protection and energy conservation, and particularly to a method for testing and evaluating the degradation performance of degradable straw drainage boards. Background Art

[0002] According to the environmental conditions and mechanisms causing degradation, degradable materials can be roughly divided into: photo-degradable plastics, thermo-oxidative degradable plastics, biodegradable plastics, and compostable plastics, etc. Among them, biodegradable plastics refer to those that are degraded by the action of naturally occurring microorganisms under natural conditions such as soil (sand), composting conditions, anaerobic digestion conditions, or aqueous culture solutions, and are ultimately completely degraded into carbon dioxide CO 2 (methane CH 4 ), water, mineral inorganic salts, and new biodegradable plastics. Compostable plastic degradation means that under composting conditions, due to the biological reaction process, the plastic can be degraded and disintegrated, and ultimately completely decomposed into carbon dioxide, water, mineralized inorganic salts, and new biomass, and the heavy metal content, toxicity test, residual fragments, etc. of the finally formed compost must meet the relevant standard requirements. It can be seen that compostable plastics are actually a type of biodegradable plastics. Whether it is biodegradable plastics or compostable plastics, the degradation of microorganisms on them mainly occurs in the following three forms: 1) Biophysical action, where mechanical damage to the polymer occurs due to the growth of cells after microbial erosion; 2) Biochemical action, where the action of microbial metabolism on the polymer produces new substances such as organic acids, H 2 0, CO 2 etc.; 3) Extracellular enzyme degradation action, mainly referring to the hydrolysis of the polymer by extracellular enzymes to form short chains or polymer monomers.

[0003] At present, among the standard methods for detecting degradable plastics, GB / T19276.1-2003 Determination of the Ultimate Aerobic Biodegradability of Materials in an Aqueous Medium - Method by Measuring the Oxygen Demand in a Closed Respirometer (equivalent to ISO14851:1999), GB / T19276.2-2003 Determination of the Ultimate Aerobic Biodegradability of Materials in an Aqueous Medium - Method by Measuring the Evolved Carbon Dioxide (equivalent to ISO14852:1999), GB / T19277-2011 Determination of the Ultimate Aerobic Biodegradability and Disintegration of Materials under Controlled Composting Conditions - Method by Measuring the Evolved Carbon Dioxide (equivalent to ISO14855:2003), GB / T19811-2005 Determination of the Degree of Disintegration of Plastic Materials under Defined Pilot-Scale Composting Conditions (equivalent to ISO16929:2002), and GB / T19275-2003 Evaluation of the Potential Biodegradability and Disintegration of Materials under the Action of Specific Microorganisms (equivalent to ISO846:1997) are widely adopted in China. It can be seen from the above test methods that microbiological methods are mainly used for testing the biodegradable properties of materials at home and abroad. Microbiological methods generally have a long cycle. For example, specific microorganism degradation requires 28 days (ISO846:1997, GB / T19275-2003), and the longest detection cycles of the aqueous culture method (ISO14851:1999, GB / T19276.1-2003) and the controlled composting method (ISO14855:2003, GB / T19277-2003) both require 6 months. When testing the degradation characteristics of degradable materials in relevant specifications, the degradation characteristics in the actual specific soil environment are not described and elaborated, resulting in the biodegradation rate of degradable materials not conforming to the relevant performance indicators in actual use, severely restricting both product inspection and the promotion of production applications. Therefore, it is urgent to test the degradation characteristics of degradable materials according to environmental variability, which is also an issue that needs to be solved urgently.

[0004] The evaluation methods of biodegradable materials mainly depend on their biodegradability, and the degradation can be evaluated by the following methods according to current specifications: (1) Represented by the growth rate on the degradation films of different colonies. The greater the microbial coverage of the biodegradable film in the soil suspension within one month, the better the degradation performance. (2) Represented by the percentage of weight loss. The higher the percentage of weight loss within a certain period, the better the degradation performance. (3) Represented by mechanical properties. After the biodegradable material comes into contact with the soil or is buried in the soil, the faster the mechanical properties decrease, the better the degradation performance. However, during the degradation process of the degradable straw drainage board, it is necessary to maintain the retention of its mechanical properties and its engineering drainage characteristics, so new improvements need to be made to the degradation evaluation method to suit the characteristics of the geotechnical engineering field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for testing and evaluating the degradation performance of degradable straw drainage boards in view of the deficiencies of the above-mentioned prior art. The method for testing and evaluating the degradation performance of degradable straw drainage boards combines the mechanical property degradation, material drainage property degradation and weight loss rate in the geotechnical engineering field, comprehensively considers the three factors by the analytic hierarchy process, obtains a new evaluation model for the degradation rate of degradable straw drainage board materials, and the evaluation is simple and accurate, and can realize the simple detection of the degradation performance of degradable straw drainage boards.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for testing and evaluating the degradation performance of degradable straw drainage boards, comprising the following steps.

[0008] Step 1, biodegradation: Make the degradable straw drainage board into samples with set specifications and sizes, and subject a part of the samples to biodegradation for a set number of days.

[0009] Step 2, calculate the relative degradation rate r of mechanical properties 1 : Conduct tensile property tests on the samples that have not undergone biodegradation and the samples that have completed biodegradation in Step 1, and record the tensile strengths of both; among them, F 0 is the tensile strength of the sample after biodegradation, and F is the tensile strength of the sample before biodegradation; then the relative degradation rate r of mechanical properties 1 is calculated by the formula:

[0010] r 1 = (F 0 - F) / F 0 × 100%

[0011] Step 3, calculate the relative degradation rate r of drainage performance 2 : Conduct drainage performance tests on the samples that have not undergone biodegradation and the samples that have completed biodegradation in Step 1, and record the water passing capacities of both; among them, P 0 is the water passing capacity of the sample after biodegradation, and P is the water passing capacity of the sample before biodegradation; then the relative degradation rate r of drainage performance 2 is calculated by the formula:

[0012] r 2 = (P 0 - P) / P 0 × 100%

[0013] Step 4, calculate the relative degradation rate r of straw 3 : First weigh the samples that have completed biodegradation in Step 1, and record it as W 0; Next, the weighed biodegradable sample is dried and weighed, and the weight of the dried biodegradable sample is recorded as W; then the relative degradation rate r of the straw 3 is calculated by the following formula:

[0014] r 3 =(W 0 -W) / W 0 ×100%

[0015] Step 5. Construct a degradation rate evaluation model r, specifically:

[0016] r = r 1 *w 1 +r 2 *w 2 +r 3 *w 3

[0017] where w 1 、w 2 and w 3 are all the weight coefficients of r 1 、r 2 and r 3 , and are determined by the analytic hierarchy process.

[0018] In Step 5, the method for determining w 1 、w 2 and w 3 includes the following steps:

[0019] Step 51. Construct a judgment matrix R, and the specific expression is:

[0020]

[0021] where r 11 represents the importance degree of the relative degradation rate r of the mechanical property 1 relative to itself; r 12 represents the importance degree of the relative degradation rate r of the mechanical property 1 relative to the relative degradation rate r of the drainage performance 2 ; r 13 represents the importance degree of the relative degradation rate r of the mechanical property 1 relative to the relative degradation rate r of the straw 3 ; r 21 represents the importance degree of the relative degradation rate r of the drainage performance 2 relative to the relative degradation rate r of the mechanical property 1 ; r 22 represents the importance degree of the relative degradation rate r of the drainage performance 2 relative to itself; r 23 represents the relative degradation rate r of the drainage performance2 The importance level of the relative degradation rate r of straw 3 ; r 31 represents the relative degradation rate r of straw 3 The importance level of the relative degradation rate r with respect to the mechanical properties 1 ; r 32 represents the relative degradation rate r of straw 3 The importance level of the relative degradation rate r with respect to the drainage performance 2 ; r 33 represents the relative degradation rate r of straw 3 The importance level with respect to itself.

[0022] Step 52: Determine r ij : Let any factor in the judgment matrix R be r ij , and 1 ≤ i ≤ 3; 1 ≤ j ≤ 3; Then, assign a value to r according to the scaling method ij .

[0023] Step 53: Calculate the average weight vector The specific calculation formula is:

[0024]

[0025]

[0026] In the formula, m i is the product of the elements in each row of the judgment matrix R, where i = 1, 2, 3.

[0027] Step 54: Determine w 1 , w 2 and w 3 , and the specific calculation formula is:

[0028]

[0029] In the formula, i = 1, 2, 3.

[0030] It also includes Step 55: Consistency check: Introduce the consistency ratio CR to conduct a consistency check on the judgment matrix R constructed in Step 51; when the consistency ratio CR is less than the set threshold, it is considered that the constructed judgment matrix R has satisfactory consistency, otherwise, reassign the value of r in the judgment matrix R ij , and repeat Steps 52 to 54 until the consistency ratio CR is less than the set threshold.

[0031] The calculation formula of the consistency ratio CR is:

[0032]

[0033]

[0034]

[0035]

[0036] Wherein, CR is the consistency ratio, CI is the consistency index, RI is the average consistency index value, and λ MAX is the maximum eigenvalue, and λ i is the eigenvalue of the judgment matrix obtained by pairwise comparison of the corresponding hierarchical indicators.

[0037] In step 55, the set threshold of the consistency ratio CR is 0.10.

[0038] In step 1, the method of biodegradation is as follows: The sample is buried in soil in a dim room under the conditions of 20-25°C and 70-80% relative humidity, and after 5, 10, 15, 30, 60, 90, 120, 150, 180 days, the sample is removed; wherein, the number of samples per day is not less than 3.

[0039] In step 1, the set specification size of the sample is a cuboid of 10 cm × 60 cm × 40 mm; in step 1, the material of the degradable straw drainage board is any kind of composition of straw, wood chips, reed, corncob, corn straw, wheat straw, bamboo fiber, rice husk powder, hemp tendon or glass fiber filament, adhesive.

[0040] In step 2, the method of tensile property test is as follows: Tensile test is carried out by using a strain control testing machine until the sample is damaged; wherein, the tensile rate is 50 mm / min.

[0041] In step 3, the method of drainage performance test includes the following steps:

[0042] Step 31, applying lateral pressure and hydraulic gradient: Using a horizontal water permeability measuring instrument for drainage board materials, applying a lateral pressure of 350 kPa to the sample through a latex film, and applying a hydraulic gradient of 0.5.

[0043] Step 32, testing the water permeability: It is carried out after the sample has percolated for 1 h under stable lateral pressure and hydraulic gradient, and the water permeability is tested once per hour until the difference between the water permeabilities of the previous and the next times is less than 5% of the water permeability of the previous time, and the last test result is used as the water permeability of the sample to be tested.

[0044] In step 4, the drying method is as follows: The sample is rinsed clean with sterile water and placed in a high-temperature oven at 65°C for drying for 8 h until constant weight.

[0045] The present invention has the following beneficial effects:

[0046] 1. The present invention conducts in-situ soil degradation tests in a specific soil burial environment, which is simple, efficient, and easy to implement.

[0047] 2. Based on the degradation of degradable straw drainage board materials in the field of geotechnical engineering, the present invention first proposes a comprehensive evaluation of the degradation rate of degradable straw drainage boards by using the degradation of physical and mechanical properties, the degradation of drainage performance, and the weight loss rate. Combining physical disintegration and biodegradation, it re-evaluates the analysis of the degradation rate in the field of geotechnical engineering and gives a new standard for determining the service life of materials.

[0048] 3. The present invention lays a foundation for the popularization and application of degradable straw base materials in the field of geotechnical engineering, provides reference for the subsequent research on similar degradable materials in engineering, and also realizes the goals of green engineering construction and urban ecological environmental protection in the field of geotechnical engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It shows the curves of the degradation rate of mechanical properties, the degradation rate of drainage performance, and the weight loss rate changing with time respectively.

[0050] Figure 2 It shows the graph of the degradation rate after comprehensive evaluation in the present invention changing with time DETAILED DESCRIPTION OF THE INVENTION

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0052] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0053] The present invention simulates the degradation environment through the soil burial test environmental conditions of different engineering soil environments, and proves that the degradation in the field of geotechnical engineering includes physical disintegration and microbial degradation. This method can not only verify the adaptability of degradable materials in different engineering soil environments, but also identify the dominant bacteria suitable for degradable straw materials in the future, and further identify their activity and degradation performance.

[0054] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0055] Such asFigure 1 As shown in Figure 1 , a method for testing and evaluating the degradation performance of a degradable straw drainage board includes the following steps.

[0056] In the present invention, the material of the degradable straw drainage board is preferably a composition of any kind among rice straw, wood chips, reed, corncob, corn straw, wheat straw, bamboo fiber, rice husk powder, hemp fiber or glass fiber filament, adhesive, etc.

[0057] In this embodiment, the degradable straw drainage board preferably comprises the following raw materials in parts by mass: 13 - 17 parts of rice straw, 10 - 13 parts of wood chips, 3 - 5 parts of reed, 5 - 8 parts of corncob, 13 - 17 parts of corn straw, 12 - 17 parts of wheat straw, 2 - 5 parts of bamboo fiber, 7 - 12 parts of rice husk powder, 4 - 8 parts of hemp fiber or glass fiber filament, and 30 - 35 parts of adhesive.

[0058] Step 1, biodegradation

[0059] First, make the degradable straw drainage board into samples with set specification dimensions, and the set specification dimensions are preferably a cuboid of 10 cm × 60 cm × 40 mm.

[0060] Then, subject a part of the samples to biodegradation for a set number of days. The preferred method of biodegradation is: bury the samples in soil in a dim room under the conditions of 20 - 25°C and 70 - 80% relative humidity, and after 5, 10, 15, 30, 60, 90, 120, 150, 180 days, remove the samples; among them, the number of samples per day is not less than 3.

[0061] The soil taken for the above burying preferably comes from the silt soil in a certain place in Zhuhai, which is dark gray, rich in microorganisms. The basic characteristics of the degradation soil environment are shown in Table 1 below.

[0062] Table 1 Basic physical and chemical indexes of the soil body

[0063]

[0064] According to research, the soil environment with a pH acidity value close to neutral is suitable for the growth of some fiber - degrading microorganisms. The higher the organic matter content above 1.5%, the more bacterial communities exist, and the greater the possibility of degrading straw fibers. The higher the natural water content, the greater the consistency value of the soil body represented by the liquid limit and plastic limit, indicating that the soil body has a stronger ability to enrich water content, is more suitable for the growth of microorganisms, and is more suitable for the biodegradation of straw fibers.

[0065] Step 2, calculate the relative degradation rate r of mechanical properties 1

[0066] Conduct tensile property tests on the samples that have not undergone biodegradation and the samples that have completed biodegradation in Step 1, and record the tensile strengths of both.

[0067] The preferred method for the above tensile property test is as follows: Use a strain-controlled testing machine to conduct the tension until the sample is damaged; among them, the tensile rate is 50 mm / min, preferably repeat 5 times, and take the average value.

[0068] Let F 0 be the tensile strength of the sample after biodegradation, and F be the tensile strength of the sample before biodegradation; then the relative degradation rate r 1 of the mechanical property is calculated by the following formula:

[0069] r 1 =(F 0 -F) / F 0 ×100%

[0070] Samples that have undergone landfill degradation for 5, 10, 15, 30, 60, 90, 120, 150, and 180 days are respectively subjected to the above tensile property test, and then the relative degradation rate r 1 of the mechanical property versus time curve is obtained, as Figure 1 shown.

[0071] Step 3. Calculate the relative degradation rate r 2 of the drainage performance:

[0072] Conduct drainage performance tests on the samples that have not undergone biodegradation and the samples that have completed biodegradation in Step 1, and record the water permeability of both.

[0073] The preferred method for the above drainage performance test includes the following steps:

[0074] Step 31. Apply lateral pressure and hydraulic gradient: Use a horizontal water permeability tester for drainage board materials to apply a 350 kPa lateral pressure to the sample through a latex film, and apply a hydraulic gradient of 0.5, preferably repeat 2 times, and take the average value.

[0075] Step 32. Test the water permeability: Conduct it after the sample has percolated for 1 h under a stable lateral pressure and hydraulic gradient, test the water permeability once per hour until the difference between the water permeabilities of the last two times is less than 5% of the water permeability of the previous time, and take the result of the last test as the water permeability of the sample to be tested.

[0076] Let P 0 be the water permeability of the sample after biodegradation, and P be the water permeability of the sample before biodegradation; then the relative degradation rate r 2 of the drainage performance is calculated by the following formula:

[0077] r 2 =(P 0 -P) / P 0 ×100%

[0078] Samples that have been buried and degraded for 5, 10, 15, 30, 60, 90, 120, 150, and 180 days are respectively subjected to the above drainage performance tests, and then the relative degradation rate r of the drainage performance is obtained. 2 The curve of change with time is as Figure 1 shown.

[0079] Step 4: Calculate the relative degradation rate r of the straw 3

[0080] First, weigh the sample that has completed biodegradation in Step 1 and record it as W 0 ; then, dry and weigh the biodegradable sample after weighing. Among them, the drying method is preferably: rinse the sample with sterile water, and place it in a high-temperature oven at 65 °C for 8 h until it reaches a constant weight. Preferably, repeat 3 times and take the average value.

[0081] Then, record the weight of the dried biodegradable sample as W; then the relative degradation rate r of the straw 3 The calculation formula is:

[0082] r 3 =(W 0 -W) / W 0 ×100%

[0083] Samples that have been buried and degraded for 5, 10, 15, 30, 60, 90, 120, 150, and 180 days are respectively subjected to the above drying and weighing, and then the relative degradation rate r of the straw with respect to the change with time is obtained. 3 The curve of change with time is as Figure 1 shown.

[0084] Step 5: Construct a degradation rate evaluation model r, specifically:

[0085] r = r 1 *w 1 +r 2 *w 2 +r 3 *w 3

[0086] Among them, w 1 , w 2 and w 3 are all weight coefficients of r 1 , r 2 and r 3 .

[0087] The above w 1 , w 2 and w 3 are preferably determined by the analytic hierarchy process, and the determination method preferably includes the following steps.

[0088] Step 51. Construct a judgment matrix \(R\), and the specific expression is as follows:

[0089]

[0090] where \(r\) 11 represents the relative degradation rate \(r\) 1 of mechanical properties with respect to its own importance; \(r\) 12 represents the relative degradation rate \(r\) 1 of mechanical properties with respect to the relative degradation rate \(r\) 2 of drainage performance; \(r\) 13 represents the relative degradation rate \(r\) 1 of mechanical properties with respect to the relative degradation rate \(r\) 3 of straw; \(r\) 21 represents the relative degradation rate \(r\) 2 of drainage performance with respect to the relative degradation rate \(r\) 1 of mechanical properties; \(r\) 22 represents the relative degradation rate \(r\) 2 of drainage performance with respect to its own importance; \(r\) 23 represents the relative degradation rate \(r\) 2 of drainage performance with respect to the relative degradation rate \(r\) 3 of straw; \(r\) 31 represents the relative degradation rate \(r\) 3 of straw with respect to the relative degradation rate \(r\) 1 of mechanical properties; \(r\) 32 represents the relative degradation rate \(r\) 3 of straw with respect to the relative degradation rate \(r\) 2 of drainage performance; \(r\) 33 represents the relative degradation rate \(r\) 3 of straw with respect to its own importance.

[0091] Step 52. Determine \(r\) ij : Let any factor in the judgment matrix \(R\) be \(r\) ij , and \(1\leq i\leq3\); \(1\leq j\leq3\); then, according to the scale method shown in Table 2, assign a value to \(r\) ij .

[0092] Table 2 Scale method value table

[0093]

[0094] In this embodiment, using the above scale method and according to the actual situation, after initially assigning a value to \(r\) ij , the following judgment matrix \(R\) is obtained:

[0095]

[0096] Step 53: Calculate the average weight vector The specific calculation formula is as follows:

[0097]

[0098]

[0099] In the formula, m i is the product of the elements in each row of the judgment matrix R, where i = 1, 2, 3.

[0100] Step 54: Determine w 1 , w 2 and w 3 , and the specific calculation formula is as follows:

[0101]

[0102] In the formula, i = 1, 2, 3. In this embodiment, it is obtained that: w 1 = 0.626, w 2 = 0.247, w 3 = 0.127.

[0103] Step 55: Consistency check: Introduce the consistency ratio CR to perform a consistency check on the judgment matrix R constructed in Step 51; when the consistency ratio CR is less than the set threshold (preferably 0.10), it is considered that the constructed judgment matrix R has satisfactory consistency. Otherwise, reassign r ij in the judgment matrix R, and repeat Steps 52 to 54 until the consistency ratio CR is less than the set threshold.

[0104] The calculation formula of the above consistency ratio CR is preferably:

[0105]

[0106]

[0107]

[0108]

[0109] In the formula, CR is the consistency ratio; CI is the consistency index; RI is the average consistency index value, which is given according to the standard 1-9 order random consistency index value experience, as shown in Table 3. In this embodiment, since the judgment matrix is a third order, RI = 0.58 is taken; λ MAX is the largest eigenvalue; λ i is the eigenvalue obtained by pairwise comparison of the corresponding hierarchical indicators.

[0110] Table 3 Standard 1-9 order random consistency index empirical values

[0111]

[0112] In the present invention, samples that have been landfilled and degraded for 5, 10, 15, 30, 60, 90, 120, 150, and 180 days are respectively subjected to the above-mentioned tensile, drainage, and drying tests, and then the curve of the degradation rate evaluation model r varying with time is obtained, as Figure 2 shown.

[0113] The material degradation rate of the present invention after being processed and calculated by the degradation rate evaluation model r is 33.2% at 240 days. This is lower than 45.8% of the evaluation index of the mechanical property loss alone, indicating that the material still has good drainage performance and small mass loss when the mechanical loss is too large; it is higher than 20.3% of the evaluation index of the drainage performance loss alone, indicating that there is a risk of mechanical damage to the material when the drainage performance is within the design requirements; it is higher than 13.4% of the evaluation index of the mass loss alone, indicating that there is a relatively large performance loss of the material when the material degradation loss is small.

[0114] When taking 30% (assumed reference value) of the performance loss of the drainage board material as the failure criterion, the service life of the material characterized by each evaluation index is shown in Table 4.

[0115] Table 4 Evaluation of the service life of each index of the drainage board material

[0116]

[0117] The degradation rate evaluation model r of the present invention takes into account the factors of the drainage board material in the geotechnical field in terms of mechanics, drainage, and weight loss, conducts an overall analysis to give a comprehensive index, avoids the engineering risks brought by single evaluation index evaluation, redefines the service life of the degradable drainage board material, and provides new data basis for engineering design.

[0118] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A method for testing and evaluating the degradation performance of degradable straw drainage boards, characterized in that: It includes the following steps: Step 1, biodegradation: Make the degradable straw drainage board into samples with set specifications and sizes, and subject a part of the samples to biodegradation for a set number of days; Step 2: Calculate the relative degradation rate r of mechanical properties 1 : Conduct tensile property tests on the samples that have not undergone biodegradation and the samples that have completed biodegradation in Step 1, and record the tensile strengths of both; where F 0 is the tensile strength of the sample after biodegradation, and F is the tensile strength of the sample before biodegradation; then the relative degradation rate r 1 is calculated by the formula: r 1 = (F 0 - F) / F 0 × 100% Step 3: Calculate the relative degradation rate r of drainage performance 2 : Conduct drainage performance tests on the samples that have not undergone biodegradation and the samples that have completed biodegradation in Step 1, and record the water throughput of both; where P 0 is the water throughput of the sample after biodegradation, and P is the water throughput of the sample before biodegradation; then the relative degradation rate r 2 is calculated by the formula: r 2 = (P 0 - P) / P 0 × 100% Step 4: Calculate the relative degradation rate r of straw 3 : First, weigh the sample that has completed biodegradation in Step 1 and record it as W 0 ; Then, dry and weigh the biodegradation sample after weighing, and record the weight of the dried biodegradation sample as W; then the relative degradation rate r of straw 3 is calculated by the formula: r 3 = (W 0 - W) / W 0 × 100% Step 5, construct a degradation rate evaluation model r, specifically: r = r 1 *w 1 +r 2 *w 2 +r 3 *w 3 Among them, w 1 , w 2 and w 3 are all weight coefficients of r 1 , r 2 and r 3 , and are determined by the analytic hierarchy process; Among them, w 1 , w 2 and w 3 are determined by the analytic hierarchy process, including the following steps: Step 51, construct a judgment matrix R, and the specific expression is: Among them, r 11 represents the relative degradation rate r of mechanical properties 1 with respect to its own importance; r 12 represents the relative degradation rate r of mechanical properties 1 with respect to the relative degradation rate r of drainage performance 2 of importance; r 13 represents the relative degradation rate r of mechanical properties 1 with respect to the relative degradation rate r of straw 3 of importance; r 21 represents the relative degradation rate r of drainage performance 2 with respect to the relative degradation rate r of mechanical properties 1 of importance; r 22 represents the relative degradation rate r of drainage performance 2 with respect to its own importance; r 23 represents the relative degradation rate r of drainage performance 2 with respect to the relative degradation rate r of straw 3 of importance; r 31 represents the relative degradation rate r of straw 3 with respect to the relative degradation rate r of mechanical properties 1 of importance; r 32 represents the relative degradation rate r of straw 3 with respect to the relative degradation rate r of drainage performance 2 of importance; r 33 represents the relative degradation rate r of straw 3 with respect to its own importance; Step 52, determine r ij : Let any factor in the judgment matrix R be r ij , and 1 ≤ i ≤ 3; 1 ≤ j ≤ 3; then, assign a value to r ij according to the scaling method; Step 53, calculate the average weight vector The specific calculation formula is as follows: where m i is the product of the elements in each row of the judgment matrix R, where i = 1, 2, 3; Step 54, determine w 1 , w 2 and w 3 , and the specific calculation formula is: where i = 1, 2, 3; Step 55, Consistency check: Introduce the consistency ratio CR to perform a consistency check on the judgment matrix R constructed in Step 51; when the consistency ratio CR is less than the set threshold, it is considered that the constructed judgment matrix R has satisfactory consistency, otherwise, reassign the r ij in the judgment matrix R, and repeat Steps 52 to 54 until the consistency ratio CR is less than the set threshold; Among them, the calculation formula for the consistency ratio CR is: where CR is the consistency ratio, CI is the consistency index, RI is the average consistency index value, and λ MAX is the maximum eigenvalue, and λ i is the eigenvalue of the judgment matrix obtained by pairwise comparison of the corresponding hierarchical indicators.

2. The method for testing and evaluating the degradation performance of degradable straw drainage boards according to claim 1, characterized in that: In step 55, the set threshold value of the consistency ratio CR is 0.

10.

3. The method for testing and evaluating the degradation performance of degradable straw drainage boards according to claim 1, characterized in that: The method of biodegradation in step 1 is: Bury the samples in soil in a dim room under the conditions of 20 - 25°C and 70 - 80% relative humidity, and after 5, 10, 15, 30, 60, 90, 120, 150, 180 days, remove the samples; among them, the number of samples per day is not less than 3.

4. The method for testing and evaluating the degradation performance of degradable straw drainage boards according to claim 1, characterized in that: In step 2, the method for testing the tensile performance is: Use a strain control testing machine to perform tensile testing until the sample is damaged; among them, the tensile rate is 50 mm / min.

5. The method for testing and evaluating the degradation performance of degradable straw drainage boards according to claim 1, characterized in that: In step 3, the method for testing the drainage performance includes the following steps: Step 31, apply lateral pressure and hydraulic gradient: Use a horizontal water permeability measuring instrument for drainage board materials to apply a 350 kPa lateral pressure to the sample through a latex film, and apply a hydraulic gradient of 0.5; Step 32, test the water permeability: It is carried out after the sample has percolated for 1 h under a stable lateral pressure and hydraulic gradient. The water permeability is tested once per hour until the difference between the water permeabilities of the last two times is less than 5% of the water permeability of the previous time, and the last test result is used as the water permeability of the sample to be tested.

6. The method for testing and evaluating the degradation performance of degradable straw drainage boards according to claim 1, characterized in that: In step 4, the drying method is: Rinse the sample clean with sterile water and place it in a high-temperature oven at 65°C for drying for 8 h until it reaches a constant weight.

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