Method and system for predicting crushing strength of rockfill material by considering stress-dry-wet cycle coupling effect

Abstract

The invention provides a rockfill material crushing strength prediction method and system considering a stress-dry-wet cycle coupling effect. The method comprises the following steps: S1, obtaining multiple groups of rockfill material samples; s2, carrying out stress-dry-wet cycle coupling tests under different dry-wet cycle times N and different stresses P on each group of rockfill material samples; s3, performing a crushing test on each group of rockfill material samples subjected to the stress-dry-wet cycle coupling test; s4, constructing to obtain a rockfill material crushing strength prediction model considering the coupling influence of the stress and the number of dry-wet cycles; and S5, predicting the crushing strength of the rockfill material to be predicted under different dry-wet cycles and different stresses. According to the method, the coupling effect of stress and dry-wet circulation on the rockfill material in the actual environment of the rockfill dam is fully considered, so that the data more conforming to the crushing strength of the rockfill material can be predicted.

Description

Technical Field

[0001] The invention belongs to the technical field of rock and soil granular material test research, and in particular relates to a method and system for predicting the crushing strength of rockfill materials taking into account the stress-dry-wet cycle coupling effect. Background Art

[0002] In recent years, due to the need for comprehensive utilization and development of water resources, many high dam projects are under construction or planned in high-altitude areas. The terrain and geological conditions in the areas where these high dam projects are built are usually very complex, with frequent and high-intensity earthquakes, harsh natural environment, and inconvenient transportation. Rockfill dams have the advantages of being able to make full use of local materials, good adaptability to terrain and geological conditions, low cost, and simple construction methods. Therefore, rockfill dams have become one of the main dam types for hydropower construction in high-altitude areas.

[0003] So far, a number of 200-300m high rockfill dams are under construction or planned, including Shuangjiangkou on the Dadu River, Rumei on the Lancang River, Qizong, Lawa and Gushui on the Jinsha River. These projects are large-scale and have far-reaching significance, so it is necessary to accurately evaluate the safety and stability of high rockfill dams during operation.

[0004] Engineering practice shows that during the long-term operation of rockfill dams, the physical and mechanical properties of rockfill materials, which are the main dam-building materials, will be deteriorated by various factors, which will directly affect the overall safety of the rockfill dam. Therefore, it is currently important to determine the key factors that affect the physical and mechanical properties of rockfill materials that are more in line with the actual engineering operation environment, and to quantify the relationship between the key factors and the physical and mechanical properties of rockfill materials, so as to provide basic data support for evaluating the overall safety of rockfill dams during operation. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a method and system for predicting the crushing strength of rockfill materials taking into account the stress-dry-wet cycle coupling effect, which can effectively solve the above problems.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention provides a method for predicting the crushing strength of rockfill materials taking into account the stress-dry-wet cycle coupling effect, comprising the following steps:

[0008] Step S1, obtaining multiple groups of rockfill material samples;

[0009] Each group of rockfill material samples includes a plurality of rockfill material particles; the particle size d, the major axis L, the median axis I and the minor axis S of each rockfill material particle are recorded; each rockfill material particle in each group of rockfill material samples has the same rockfill material particle characteristics; wherein the rockfill material particle characteristics include the rockfill material particle size characteristics and the rockfill material particle shape characteristics;

[0010] Step S2, performing stress-wet-dry cycle coupling tests under different wetting-dry cycle numbers N and different stresses P on each group of rockfill material samples;

[0011] Step S3, performing a crushing test on each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test described in step S2 to obtain their crushing strength σ; thereby obtaining a plurality of test data; each test data record the corresponding relationship and value of the number of wet-dry cycles N, the crushing strength σ and the stress P;

[0012] Step S4, based on the test data obtained in step S3, studying the relationship between the crushing strength σ of the rockfill material samples and the stress P under different drying and wetting cycles N, and constructing a rockfill material crushing strength prediction model that considers the coupling effects of stress and drying and wetting cycles;

[0013] Step S5, using the rockfill material crushing strength prediction model considering the coupled effects of stress and the number of dry-wet cycles obtained in step S4, predicting the crushing strength of the rockfill material to be predicted after different dry-wet cycles and under different stresses.

[0014] Preferably, step S1 specifically comprises:

[0015] Step S1.1, preliminarily screening the rockfill material for the test, screening out a plurality of rockfill material particles with a particle size d within a set range; using a three-dimensional scanner to obtain and record shape parameters of each rockfill material particle after screening, including a major axis L, a middle axis I, and a minor axis S;

[0016] Step S1.2, for each rockfill particle after screening, according to the shape parameters (L, I, S) of each rockfill particle, calculate the particle size d and shape feature S of each rockfill particle I ;

[0017] Step S1.3, according to the particle size d and shape feature S of each rockfill material particle after screening obtained in step S1.2 I , all the rockfill particles after screening are further screened to screen out the particle size d and shape characteristics S I rockfill material particles that meet the test requirements, thereby obtaining rockfill material particles having the same rockfill material particle characteristics;

[0018] Step S1.4, grouping the plurality of rockfill material particles having the same rockfill material particle characteristics screened out in step S1.3, with each group forming a rockfill material sample.

[0019] Preferably, in step S1.2, the particle size d of the rockfill material particles is calculated using formula (1):

[0020]

[0021] Thus, the particle size d of the rockfill material particles is obtained.

[0022] Preferably, in step S1.2, the shape characteristic S of the rockfill material particles is obtained by using formula (2): I ;

[0023]

[0024] In step S1.3, the shape feature S is selected I The rockfill particles with a shape characteristic S between 0.6 and 0.8 meet the requirements. I The rockfill particles are between 0.6 and 0.8, and are specifically flat.

[0025] Preferably, in step S1.3, the particle sizes d of the screened rockfill particles differ by no more than 10%; and in step S1.4, the number of rockfill particles in the rockfill sample is no less than 30 and the lithology is the same.

[0026] Preferably, step S2 specifically comprises:

[0027] For each group of rockfill material samples, they are placed in layers into the barrel of the stress-wet-dry cycle coupling test device, and the dry density of each layer of rockfill material particles is 1.05 times the dry density of the next layer of rockfill material particles, thereby ensuring that the stress of each rockfill material particle is balanced during the stress-wet-dry cycle coupling test. After the filling is completed, the stress-wet-dry cycle coupling test is carried out under different wet-dry cycle numbers N and different stresses P.

[0028] Preferably, step S3 specifically comprises:

[0029] Step S3.1, placing each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test described in step S2 onto the lower loading plate of the crushing test device, and making the axis direction of the minor axis S of the rockfill material particles of each group of rockfill material samples parallel to the upper and lower loading plates of the crushing test device;

[0030] Step S3.2, using a crushing test device to perform a crushing test, recording the load F when the rockfill material sample is crushed, and calculating the crushing strength σ of the rockfill material sample;

[0031] Step S3.3, record the corresponding relationship and value of the number of dry-wet cycles N, crushing strength σ and stress P to form test data.

[0032] Preferably, step S3.2 is specifically:

[0033] Using formula (3), the crushing strength σ of the rockfill sample is obtained:

[0034]

[0035] Thus, the crushing strength σ of the rockfill sample is obtained.

[0036] Preferably, step S4 is specifically:

[0037] Step S4.1, assume that the number of dry-wet cycles in the test is designed to have n values, namely: N1, N2, ..., N n ;

[0038] Step S4.2, in the number of dry-wet cycles N = N i When i = 1, 2, ..., n, the relationship equation of the crushing strength σ of the rockfill sample with the stress P shown in formula (4) is obtained:

[0039] σ=a i +b i P (4)

[0040] Among them, a i ,b i N is the number of dry-wet cycles N = N i The value of the correlation coefficient a and the value of the correlation coefficient b when ;

[0041] Since the number of dry-wet cycles N is designed to have n values, the equation group of the relationship between the crushing strength σ of the rockfill sample and the stress P shown in formula (5) is obtained:

[0042]

[0043] Step S4.3, therefore, for n dry-wet cycles N, the values ​​N1, N2, ..., N n , corresponding to the n values ​​of the correlation coefficient a, they are: a1, a2, ..., a n ; The corresponding n values ​​of the correlation coefficient b are: b1, b2, ..., b n ;

[0044] Step S4.4, based on the relationship obtained in step S4.3, the correlation between the correlation coefficient a and the number of dry-wet cycles N is analyzed to obtain the correlation equation shown in formula (6); the correlation between the correlation coefficient b and the number of dry-wet cycles N is analyzed to obtain the correlation equation shown in formula (7);

[0045] a=αln(-βln(N)) (6)

[0046]

[0047] Among them: α, β, γ, η are the values ​​of the fitting coefficients in the correlation equation;

[0048] Step S4.5, thereby constructing a rockfill material crushing strength variation model considering the coupling effects of stress and dry-wet cycle times as shown in formula (8):

[0049]

[0050] Thus, a prediction model for the crushing strength of rockfill materials is obtained, which takes into account the coupling effects of stress and the number of dry-wet cycles.

[0051] The present invention also provides a system for realizing the method for predicting the crushing strength of rockfill materials taking into account the stress-dry-wet cycle coupling effect, comprising:

[0052] A preprocessing module, used for preprocessing and grouping rockfill material particles to obtain multiple groups of rockfill material samples;

[0053] A coupling and crushing test module is used to perform stress-wet-dry cycle coupling tests under different dry-wet cycle numbers N and different stresses P on each group of rockfill material samples processed by the pre-processing module, and to perform crushing tests on each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test to obtain their crushing strength σ; thereby obtaining multiple test data; each test data records the corresponding relationship and value of the dry-wet cycle number N, crushing strength σ and stress P;

[0054] The prediction model building module is used to study the relationship between the crushing strength σ of rockfill samples and stress P under different drying and wetting cycles N according to the test data, and to build a prediction model for the crushing strength of rockfill materials that takes into account the coupling effects of stress and drying and wetting cycles.

[0055] The crushing strength prediction module is used to use the rockfill crushing strength prediction model considering the coupling effect of stress and dry-wet cycle number to predict the crushing strength of the rockfill material after different dry-wet cycles and different stresses.

[0056] The method and system for predicting the crushing strength of rockfill materials considering the stress-wet-dry cycle coupling provided by the present invention have the following advantages:

[0057] The present invention provides a method and system for predicting the crushing strength of rockfill materials considering the stress-dry-wet cycle coupling effect, fully considering the influence of the stress-dry-wet cycle coupling effect on the crushing strength of rockfill materials, accurately predicting and obtaining data that is more in line with the actual crushing strength of rockfill materials in actual projects, and providing a reference for predicting the change in crushing strength of rockfill materials for dam construction in actual rockfill dam projects under the influence of reservoir water level cycle changes and the deadweight of the dam body during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1A flow chart of a method for predicting the crushing strength of rockfill materials taking into account the coupling effect of stress-wet-dry cycles provided by the present invention;

[0059] Figure 2 A graph showing the relationship between the crushing strength σ of rockfill materials and stress P under different dry-wet cycle numbers N provided by an embodiment of the present invention;

[0060] Figure 3 A correlation diagram between the fitting coefficient a and the number of dry-wet cycles N provided in an embodiment of the present invention;

[0061] Figure 4 A correlation diagram between the fitting coefficient b and the number of dry-wet cycles N provided in an embodiment of the present invention;

[0062] Figure 5 A surface diagram showing the variation of the crushing strength σ of the rockfill material provided by an embodiment of the present invention with the number of dry-wet cycles N and the stress P;

[0063] Figure 6 Typical load-displacement curves of the rockfill material provided in the embodiment of the present invention obtained after 20, 32, and 40 dry-wet cycles and a stress-dry-wet cycle coupling test with a coupling stress P of 1.5 MPa. DETAILED DESCRIPTION

[0064] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0065] The present invention provides a method and system for predicting the crushing strength of rockfill materials considering the stress-dry-wet cycle coupling effect, fully considering the influence of the stress-dry-wet cycle coupling effect on the crushing strength of rockfill materials, accurately predicting and obtaining data that is more in line with the actual crushing strength of rockfill materials in actual projects, and providing a reference for predicting the change in crushing strength of rockfill materials for dam construction in actual rockfill dam projects under the influence of reservoir water level cycle changes and the deadweight of the dam body during operation.

[0066] Specifically, the inventors have found through research that during the long-term operation of the rockfill dam, during the water storage and operation stages, the water level of the reservoir will fluctuate periodically between the dead water level and the normal water storage level. The rockfill materials inside the upstream rockfill area are therefore subject to the dry-wet cycle, and under the action of the dam body's own weight, they are also subject to the continuous action of external stress. The dry-wet cycle and the action of external stress will cause the physical and mechanical properties of the rockfill materials, such as shear strength and deformation modulus, to deteriorate significantly, thereby causing the rockfill dam to deform incoordinated and excessively, leading to cracks on the dam top and instability of the dam slope. The dry-wet cycle and the action of external stress will change the physical and mechanical properties of the rockfill materials, which is specifically manifested in that when the external stress increases, the rockfill materials are more likely to break. At the same time, under the action of the dry-wet cycle, the crushing strength of the rockfill materials will decrease.

[0067] Therefore, combined with the characteristics of the long-term operating environment of rockfill dams, it is determined that the effects of dry-wet cycles and external stress are key factors affecting the physical and mechanical properties of rockfill materials. The present invention studies the changes in the physical and mechanical properties of rockfill materials after dry-wet cycles and external stresses, and predicts and determines the crushing strength of rockfill materials after an unknown number of dry-wet cycles and unknown stresses through a limited number of test data, thereby providing a reference for predicting the changes in the physical and mechanical properties of rockfill materials for actual rockfill dam projects under the influence of reservoir water level cycles and the deadweight of the dam body during operation.

[0068] like Figure 1 As shown, the present invention provides a method for predicting the crushing strength of rockfill materials considering the stress-dry-wet cycle coupling effect, comprising the following steps:

[0069] Step S1, obtaining multiple groups of rockfill material samples;

[0070] Each group of rockfill material samples includes a plurality of rockfill material particles; the particle size d, the major axis L, the median axis I and the minor axis S of each rockfill material particle are recorded; each rockfill material particle in each group of rockfill material samples has the same rockfill material particle characteristics; wherein the rockfill material particle characteristics include the rockfill material particle size characteristics and the rockfill material particle shape characteristics;

[0071] Step S1 is specifically as follows:

[0072] Step S1.1, preliminarily screening the rockfill material for the test, screening out a plurality of rockfill material particles with a particle size d within a set range; using a three-dimensional scanner to obtain and record shape parameters of each rockfill material particle after screening, including a major axis L, a middle axis I, and a minor axis S;

[0073] Step S1.2, for each rockfill particle after screening, according to the shape parameters (L, I, S) of each rockfill particle, calculate the particle size d and shape feature S of each rockfill particle I ;

[0074] In the present invention, the particle size d of the rockfill material particles is calculated using formula (1):

[0075]

[0076] Thus, the particle size d of the rockfill material particles is obtained.

[0077] Using formula (2), the shape characteristic S of rockfill particles is obtained: I ;

[0078]

[0079] Step S1.3, according to the particle size d and shape feature S of each rockfill material particle after screening obtained in step S1.2 I , all the rockfill particles after screening are further screened to screen out the particle size d and shape characteristics S I rockfill material particles that meet the test requirements, thereby obtaining rockfill material particles having the same rockfill material particle characteristics;

[0080] As an example, the shape feature S is selected. I The rockfill particles with a shape characteristic S between 0.6 and 0.8 meet the requirements. I The rockfill particles are between 0.6 and 0.8, specifically flat. The particle size d is between 20 and 22 mm, and the particle size d does not differ by more than 10%;

[0081] Step S1.4, grouping the plurality of rockfill material particles having the same rockfill material particle characteristics screened out in step S1.3, with each group forming a rockfill material sample.

[0082] For example, the number of rockfill particles in each group of rockfill samples is no less than 30 and the lithology is the same.

[0083] Step S2, performing stress-wet-dry cycle coupling tests under different wetting-dry cycle numbers N and different stresses P on each group of rockfill material samples;

[0084] Step S2 is specifically as follows:

[0085] For each group of the rockfill material samples, they are placed in the barrel of the stress-wet-dry cycle coupling test device in layers, for example, in 5 layers, and in order to keep the rockfill material samples as uniform as possible and each rockfill material particle is more evenly stressed during the stress-wet-dry cycle coupling test, the dry density of the rockfill material particles filled in each layer is 1.05 times the dry density of the rockfill material particles in the next layer, thereby ensuring that each rockfill material particle is evenly stressed during the stress-wet-dry cycle coupling test; after the filling is completed, the stress-wet-dry cycle coupling test is carried out under different wet-dry cycle numbers N and different stresses P.

[0086] When conducting the stress-wet-dry cycle coupling test, the stress P must be set to be less than 50% of the crushing strength of the rockfill particles in the natural state, so as to ensure that all rockfill particles are not crushed during the stress-wet-dry cycle coupling test. As an embodiment, the stress P is set to be less than 4 MPa.

[0087] Step S3, performing a crushing test on each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test described in step S2 to obtain their crushing strength σ; thereby obtaining a plurality of test data; each test data record the corresponding relationship and value of the number of wet-dry cycles N, the crushing strength σ and the stress P;

[0088] Step S3 is specifically as follows:

[0089] Step S3.1, placing each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test described in step S2 onto the lower loading plate of the crushing test device, and making the axis direction of the minor axis S of the rockfill material particles of each group of rockfill material samples parallel to the upper and lower loading plates of the crushing test device;

[0090] Step S3.2, using a crushing test device to perform a crushing test, recording the load F when the rockfill material sample is crushed, and using formula (3) to obtain the crushing strength σ of the rockfill material sample:

[0091]

[0092] Thus, the crushing strength σ of the rockfill sample is obtained.

[0093] Step S3.3, record the corresponding relationship and value of the number of dry-wet cycles N, crushing strength σ and stress P to form test data.

[0094] Step S4, based on the test data obtained in step S3, studying the relationship between the crushing strength σ of the rockfill material samples and the stress P under different drying and wetting cycles N, and constructing a rockfill material crushing strength prediction model that considers the coupling effects of stress and drying and wetting cycles;

[0095] Step S4 is specifically as follows:

[0096] Step S4.1, assume that the number of dry-wet cycles in the test is designed to have n values, namely: N1, N2, ..., N n ;

[0097] Step S4.2, in the number of dry-wet cycles N = N i When i = 1, 2, ..., n, the relationship equation of the crushing strength σ of the rockfill sample with the stress P shown in formula (4) is obtained:

[0098] σ=a i +b i P (4)

[0099] Among them, a i ,b i N is the number of dry-wet cycles N = N i The value of the correlation coefficient a and the value of the correlation coefficient b when ;

[0100] Since the number of dry-wet cycles N is designed to have n values, the equation group of the relationship between the crushing strength σ of the rockfill sample and the stress P shown in formula (5) is obtained:

[0101]

[0102] Step S4.3, therefore, for n dry-wet cycles N, the values ​​N1, N2, ..., N n , corresponding to the n values ​​of the correlation coefficient a, they are: a1, a2, ..., a n ; The corresponding n values ​​of the correlation coefficient b are: b1, b2, ..., b n ;

[0103] Step S4.4, based on the relationship obtained in step S4.3, the correlation between the correlation coefficient a and the number of dry-wet cycles N is analyzed to obtain the correlation equation shown in formula (6); the correlation between the correlation coefficient b and the number of dry-wet cycles N is analyzed to obtain the correlation equation shown in formula (7);

[0104] a=αln(-βln(N)) (6)

[0105]

[0106] Among them: α, β, γ, η are the values ​​of the fitting coefficients in the correlation equation;

[0107] Step S4.5, thereby constructing a rockfill material crushing strength variation model considering the coupling effects of stress and dry-wet cycle times as shown in formula (8):

[0108]

[0109] Thus, a prediction model for the crushing strength of rockfill materials is obtained, which takes into account the coupling effects of stress and the number of dry-wet cycles.

[0110] Step S5, using the rockfill material crushing strength prediction model considering the coupled effects of stress and the number of dry-wet cycles obtained in step S4, predicting the crushing strength of the rockfill material to be predicted after different dry-wet cycles and under different stresses.

[0111] An embodiment is described below:

[0112] Step S1, obtaining multiple groups of rockfill material samples;

[0113] Step S1.1, preliminarily screening the rockfill material used for the test to screen out rockfill material particles with a particle size d of 20 to 30 mm; using a three-dimensional scanner to obtain and record the shape parameters of each rockfill material particle after screening, including a major axis L, a middle axis I, and a minor axis S;

[0114] Step S1.2, for each rockfill particle after screening, according to the shape parameters (L, I, S) of each rockfill particle, calculate the particle size d and shape feature S of each rockfill particle I ;

[0115] Step S1.3, according to the particle size d and shape characteristics S of each rockfill particle after screening I , all the rockfill particles after screening are further screened to select the particles with shape characteristics S I Flat rockfill particles with a diameter between 0.6 and 0.8 and a particle size d between 20 and 22 mm, and a particle size d difference of no more than 10%;

[0116] Step S1.4, grouping the screened multiple rockfill material particles with the same rockfill material particle characteristics into 16 groups in total, with each group of rockfill material samples containing 32 rockfill material particles with the same lithology.

[0117] Step S2, performing stress-wet-dry cycle coupling tests under different wetting-dry cycle numbers N and different stresses P on each group of rockfill material samples.

[0118] In this embodiment, the number of dry-wet cycles N is set to 0, 8, 16, and 24 times; the stress P is set to 0, 0.5, 1, and 2 MPa, so that orthogonal tests are carried out on 16 groups of rockfill material samples.

[0119] Step S3, performing a crushing test on the 16 groups of rockfill material samples that have completed the stress-wet-dry cycle coupling test.

[0120] Specifically, a crushing test is carried out on each group of rockfill samples after the stress-wet-dry cycle coupling test with a given stress P and number of wet-dry cycles N. Quasi-static loading is performed using displacement loading until the rockfill is crushed. The loading speed is controlled at 0.002 mm / s to prevent crushing due to dynamic influence. The load F when the rockfill sample is crushed is recorded, and the crushing strength σ of the rockfill sample is obtained using formula (3).

[0121] The test data are shown in Table 1:

[0122] Table 1 Summary of crushing strength of rockfill samples

[0123]

[0124]

[0125] Step S4, based on the test data obtained in Table 1, studying the relationship between the crushing strength σ of the rockfill material samples and the stress P under different drying and wetting cycles N, and constructing a rockfill material crushing strength prediction model that considers the coupling effects of stress and drying and wetting cycles;

[0126] Step S4.1, the number of dry-wet cycles N in the test is designed to have 4 values, namely 0, 8, 16, and 24 times;

[0127] Step S4.2, under each number of dry-wet cycles N, a curve of the relationship between crushing strength σ and stress P is plotted in the coordinate system, such as Figure 2 As shown, the change relationship equation is obtained:

[0128] σ=a i +b i P (4)

[0129] Among them: i=1,2,3,4, a i ,b i are the values ​​of correlation coefficient a and correlation coefficient b when the number of dry-wet cycles N is 0, 8, 16, and 24;

[0130] Step S4.3, in this embodiment, the four values ​​of the correlation coefficient a are determined to be 8.508, 7.488, 6.933, and 6.684, respectively, and the four values ​​of the correlation coefficient b are determined to be -0.023, -0.301, -0.455, and -0.440, respectively.

[0131] Step S4.4, analyzing the correlation coefficient a and the number of dry-wet cycles N, we can get Figure 3 The correlation curve between the correlation coefficient a and the number of dry-wet cycles N is shown in Figure 1. The correlation between the correlation coefficient b and the number of dry-wet cycles N is analyzed to obtain Figure 4The correlation curve shown is the correlation coefficient b and the number of dry-wet cycles N.

[0132] right Figure 3 and Figure 4 By analyzing, the correlation coefficient a and the number of dry-wet cycles N are obtained: a = αln (-βln (N)); the correlation coefficient b and the number of dry-wet cycles N are obtained: In this embodiment, the values ​​of the fitting coefficients α, β, γ, and η are determined to be -1.900, -0.009, 1.903, and -0.1, respectively.

[0133] Therefore, a = -1.9ln(0.009ln(N)),

[0134] Step S4.5, construct a rockfill material crushing strength variation model that considers the coupling effects of stress and dry-wet cycles:

[0135] Substituting the values ​​of fitting coefficients α, β, γ, and η into the rockfill crushing strength variation model, the final rockfill crushing strength prediction model considering the coupling effects of stress and dry-wet cycles is obtained:

[0136]

[0137] like Figure 5 As shown, a surface showing the variation of the crushing strength σ of the rockfill material with the number of dry-wet cycles N and the stress P is plotted. The crushing strength σ of the rockfill material under any number of dry-wet cycles N and any stress P can be determined and predicted through this surface.

[0138] Step S5, using the obtained rockfill material crushing strength prediction model considering the coupling effects of stress and the number of dry-wet cycles, predicting the crushing strength of the rockfill material to be predicted after different dry-wet cycles and under different stresses.

[0139] Furthermore, the rockfill material crushing strength prediction model proposed in the present invention is verified:

[0140] The rockfill samples with the same rockfill particle size range were subjected to stress-wet-dry cycle coupling tests with 20, 32, and 40 dry-wet cycles N and a coupling stress P of 1.5 MPa. Then, a crushing test was carried out. The typical load-displacement curves are shown in Fig. Figure 6As shown in the figure, the displacement is the distance that the loading plate moves when the rockfill sample is broken. When the loading plate moves a certain displacement, the rockfill sample will be broken, so the load F when the rockfill sample is broken is obtained, and then the crushing strength σ of the rockfill sample is obtained according to formula (3). Finally, the crushing strength σ of the rockfill sample after 20, 32, and 40 dry-wet cycles under the condition of stress P of 1.5MPa is measured to be 6.466MPa, 5.593MPa, and 5.217MPa, respectively.

[0141] The rockfill crushing strength prediction model of the present invention is used to directly predict rockfill samples with the same rockfill particle size range, and the crushing strength σ of the rockfill after 20, 32, and 40 dry-wet cycles under a stress of 1.5 MPa is 6.697 MPa, 5.822 MPa, and 5.654 MPa.

[0142] It can be seen that the error between the crushing strength σ predicted by the present invention and the crushing strength σ obtained by the test measured data is less than 8%, indicating that the method of the present invention is in good agreement with the actual results.

[0143] The present invention also provides a system for realizing a method for predicting the crushing strength of rockfill materials considering the stress-wet-dry cycle coupling effect, which is used to automatically realize the method for predicting the crushing strength of rockfill materials considering the stress-wet-dry cycle coupling effect provided by the present invention, comprising:

[0144] A preprocessing module, used for preprocessing and grouping rockfill material particles to obtain multiple groups of rockfill material samples;

[0145] Specifically, the preprocessing module can execute the contents described in step S1 above, perform preliminary screening on the rockfill material used for the test, obtain its shape parameters using a three-dimensional scanner for the preliminary screened rockfill material, and calculate the particle size d and shape feature S of each rockfill material particle according to the shape parameters. I ; Screen out rockfill particles with the same rockfill particle characteristics; wherein the rockfill particle characteristics are rockfill particles with substantially the same particle diameter d and a flat shape; group the screened multiple rockfill particles with the same rockfill particle characteristics, and each group forms a rockfill sample.

[0146] A coupling and crushing test module is used to perform stress-wet-dry cycle coupling tests under different dry-wet cycle numbers N and different stresses P on each group of rockfill material samples processed by the pre-processing module, and to perform crushing tests on each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test to obtain their crushing strength σ; thereby obtaining multiple test data; each test data records the corresponding relationship and value of the dry-wet cycle number N, crushing strength σ and stress P;

[0147] Specifically, the coupling and crushing test module can execute the contents described in the above step S2 and step S3, and put the groups of rockfill material samples screened by the preprocessing module into the stress-wet-dry cycle coupling test device in batches to carry out stress-wet-dry cycle coupling tests under different wet-dry cycle numbers N and different stresses P; take out the rockfill material samples after completing the stress-wet-dry cycle coupling test under a predetermined wet-dry cycle number N and a predetermined stress P from the stress-wet-dry cycle coupling test device, carry out a crushing test on each group of rockfill material samples, and determine the crushing strength σ of the rockfill material samples.

[0148] The prediction model building module is used to study the relationship between the crushing strength σ of rockfill samples and stress P under different drying and wetting cycles N according to the test data, and to build a prediction model for the crushing strength of rockfill materials that takes into account the coupling effects of stress and drying and wetting cycles.

[0149] The prediction model building module can execute the content described in step S4 above and establish the relationship equation between the crushing strength σ of the rockfill material sample and the stress P: σ = a i +b i P; where a i ,b i N is the number of dry-wet cycles N = N i The value of the correlation coefficient a and the value of the correlation coefficient b when the dry-wet cycle is 0.05; the correlation equation between the correlation coefficient a and the number of dry-wet cycles N is constructed: a = αln (-βln (N)); the correlation equation between the correlation coefficient b and the number of dry-wet cycles N is constructed: Among them: α, β, γ, η are the values ​​of the fitting coefficients in the correlation equation;

[0150] Finally, a rockfill crushing strength variation model considering the coupling effects of stress and dry-wet cycles was constructed:

[0151] The crushing strength prediction module is used to use the rockfill crushing strength prediction model considering the coupling effect of stress and dry-wet cycle number to predict the crushing strength of the rockfill material after different dry-wet cycles and different stresses.

[0152] The crushing strength prediction module can execute the contents described in step S5 above, and predict the crushing strength of the rockfill material to be predicted after different dry-wet cycles and under different stresses.

[0153] Furthermore, it may also include an input display module and a control module:

[0154] The input display module is used to receive the control instructions input by the operator, and display the input, output and intermediate processing data of the corresponding module in the form of text, list, static or dynamic trend chart according to the control instructions.

[0155] The control module is connected to the pre-processing module, the coupling and crushing test module, the prediction model building module, the crushing strength prediction module and the input display module to control the operation of each module.

[0156] The method and system for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle provided by the present invention have the following characteristics:

[0157] (1) The present invention relates to a method and system for predicting the crushing strength of rockfill materials considering the coupling effect of stress and dry-wet cycles. It is the first time to propose a prediction model for the crushing strength of rockfill materials considering the coupling effect of stress and dry-wet cycles. The data obtained from the experiment are brought into the model to determine the values ​​of various parameters, and the final prediction model can be obtained.

[0158] (2) The rockfill crushing strength prediction model considering the coupling effects of stress and dry-wet cycle number proposed in the present invention can predict the crushing strength of rockfill under any stress and dry-wet cycle number. The prediction result is more in line with the actual situation, and can accurately quantify the effects of the cycle number and stress on the crushing strength of rockfill, providing reliable data for the crushing strength changes of rockfill in actual rockfill dam projects under the influence of reservoir water level cycle changes and dam body deadweight during operation. For example, it is used to determine the crushing strength of rockfill in core rockfill dams after experiencing the coupling effects of reservoir water level cycle rise and fall and dam body deadweight.

[0159] (3) The present invention only needs to conduct stress-wet-dry cycle coupling tests with different stresses and different numbers of wet-dry cycles on a small amount of rockfill materials, and conduct a crushing test on the rockfill materials after the stress-wet-dry cycle coupling. The requirements for test equipment are low, the number of tests is small, the operation is simple, and the test materials and test time can be effectively saved, thereby improving work efficiency.

[0160] (4) The solution of the present invention is particularly suitable for the design stage of rockfill dam projects.

[0161] Specifically, in the design stage of a rockfill dam project, the method of the present invention is used to first determine a rockfill material sample that meets certain rockfill material particle characteristics for the test, and then perform stress-wet-dry cycle coupling test and crushing strength on the rockfill material sample to obtain a rockfill material crushing strength prediction model that considers the coupling effects of stress and the number of wet-dry cycles; the crushing strength of the rockfill material after different wet-dry cycles and under different stresses is predicted by the obtained rockfill material crushing strength prediction model to determine whether the crushing strength of the rockfill material meets the design requirements of the rockfill dam project; if it meets the requirements, it can be recommended to use a rockfill material sample that meets the rockfill material particle characteristics for dam construction. If it does not meet the requirements, the specific data of the rockfill material particle characteristics of the rockfill material sample is replaced, and the crushing strength prediction is repeated until a rockfill material sample whose crushing strength meets the design requirements of the rockfill dam project is obtained, and the dam construction is guided. Therefore, the scheme provided by the present invention can provide reference data for the selection of rockfill material samples and guide the screening of rockfill material particles for dam construction in the design stage of a rockfill dam project.

[0162] The above embodiments are merely examples of the technical solutions of the present invention. The method and system for predicting the crushing strength of rockfill materials considering the stress-wet-dry cycle coupling effect involved in the present invention are not limited to the contents described in the above embodiments, but are subject to the scope defined in the claims. Any modification, supplement or equivalent replacement made by technicians in the field of the present invention based on the embodiment is within the scope of protection required by the claims of the present invention.

Claims

1. A method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle, characterized in that: The steps include: Step S1, obtaining multiple groups of rockfill material samples; Each group of rockfill material samples includes a plurality of rockfill material particles; the particle size d, the major axis L, the median axis I and the minor axis S of each rockfill material particle are recorded; each rockfill material particle in each group of rockfill material samples has the same rockfill material particle characteristics; wherein the rockfill material particle characteristics include the rockfill material particle size characteristics and the rockfill material particle shape characteristics; Step S2, performing stress-wet-dry cycle coupling tests under different wet-dry cycle numbers N and different stresses P on each group of rockfill material samples; Step S3, performing a crushing test on each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test described in step S2 to obtain their crushing strength σ; thereby obtaining a plurality of test data; each test data record the corresponding relationship and value of the number of wet-dry cycles N, the crushing strength σ and the stress P; Step S4, based on the test data obtained in step S3, studying the relationship between the crushing strength σ of the rockfill material samples and the stress P under different drying and wetting cycles N, and constructing a rockfill material crushing strength prediction model that considers the coupling effects of stress and drying and wetting cycles; Step S5, using the rockfill material crushing strength prediction model considering the coupled effects of stress and the number of dry-wet cycles obtained in step S4, predicting the crushing strength of the rockfill material to be predicted after different dry-wet cycles and under different stresses.

2. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle according to claim 1 is characterized in that: Step S1 is specifically as follows: Step S1.1, preliminarily screening the rockfill material for the test, screening out a plurality of rockfill material particles with a particle size d within a set range; using a three-dimensional scanner to obtain and record shape parameters of each rockfill material particle after screening, including a major axis L, a middle axis I, and a minor axis S; Step S1.2, for each rockfill particle after screening, according to the shape parameters (L, I, S) of each rockfill particle, calculate the particle size d and shape feature S of each rockfill particle I ; Step S1.3, according to the particle size d and shape feature S of each rockfill material particle after screening obtained in step S1.2 I , all the rockfill particles after screening are further screened to screen out the particle size d and shape characteristics S I rockfill material particles that meet the test requirements, thereby obtaining rockfill material particles having the same rockfill material particle characteristics; Step S1.4, grouping the plurality of rockfill material particles having the same rockfill material particle characteristics screened out in step S1.3, with each group forming a rockfill material sample.

3. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle according to claim 2 is characterized in that: In step S1.2, the particle size d of the rockfill material particles is calculated using formula (1): Thus, the particle size d of the rockfill material particles is obtained.

4. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle according to claim 2, characterized in that: In step S1.2, the shape characteristic S of the rockfill particles is obtained by using formula (2): I ; In step S1.3, the shape feature S is selected I The rockfill particles with a shape characteristic S between 0.6 and 0.8 meet the requirements. I The rockfill particles are between 0.6 and 0.8, and are specifically flat.

5. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle according to claim 2, characterized in that: In step S1.3, the particle sizes d of the screened rockfill particles differ by no more than 10%; in step S1.4, the number of rockfill particles in the rockfill sample is no less than 30 and the lithology is the same.

6. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress and dry-wet cycles according to claim 1, characterized in that: Step S2 is specifically as follows: For each group of rockfill material samples, they are placed in layers into the barrel of the stress-wet-dry cycle coupling test device, and the dry density of each layer of rockfill material particles is 1.05 times the dry density of the next layer of rockfill material particles, thereby ensuring that the stress of each rockfill material particle is balanced during the stress-wet-dry cycle coupling test. After the filling is completed, the stress-wet-dry cycle coupling test is carried out under different wet-dry cycle numbers N and different stresses P.

7. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress and dry-wet cycles according to claim 1, characterized in that: Step S3 is specifically as follows: Step S3.1, placing each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test described in step S2 onto the lower loading plate of the crushing test device, and making the axis direction of the minor axis S of the rockfill material particles of each group of rockfill material samples parallel to the upper and lower loading plates of the crushing test device; Step S3.2, using a crushing test device to perform a crushing test, recording the load F when the rockfill material sample is crushed, and calculating the crushing strength σ of the rockfill material sample; Step S3.3, record the corresponding relationship and value of the number of dry-wet cycles N, crushing strength σ and stress P to form test data.

8. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycles according to claim 7, characterized in that: Step S3.2 is specifically as follows: Using formula (3), the crushing strength σ of the rockfill sample is obtained: Thus, the crushing strength σ of the rockfill sample is obtained.

9. The method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle according to claim 1, characterized in that: Step S4 is specifically as follows: Step S4.1, assume that the number of dry-wet cycles in the test is designed to have n values, namely: N1, N2, ..., N n ; Step S4.2, in the number of dry-wet cycles N = N i When i = 1, 2, ..., n, the relationship equation of the crushing strength σ of the rockfill sample with the stress P shown in formula (4) is obtained: σ=a i +b i P (4) Among them, a i ,b i N is the number of dry-wet cycles N = N i The value of the correlation coefficient a and the value of the correlation coefficient b when ; Since the number of dry-wet cycles N is designed to have n values, the equation group of the relationship between the crushing strength σ of the rockfill sample and the stress P shown in formula (5) is obtained: Step S4.3, therefore, for n dry-wet cycles N, the values ​​N1, N2, ..., N n , corresponding to the n values ​​of the correlation coefficient a, they are: a1, a2, ..., a n ; The corresponding n values ​​of the correlation coefficient b are: b1, b2, ..., b n ; Step S4.4, based on the relationship obtained in step S4.3, the correlation between the correlation coefficient a and the number of dry-wet cycles N is analyzed to obtain the correlation equation shown in formula (6); the correlation between the correlation coefficient b and the number of dry-wet cycles N is analyzed to obtain the correlation equation shown in formula (7); a=αln(-βln(N)) (6) Among them: α, β, γ, η are the values ​​of the fitting coefficients in the correlation equation; Step S4.5, thereby constructing a rockfill material crushing strength variation model considering the coupling effects of stress and dry-wet cycle times as shown in formula (8): Thus, a prediction model for the crushing strength of rockfill materials is obtained, which takes into account the coupling effects of stress and the number of dry-wet cycles.

10. A system for implementing the method for predicting the crushing strength of rockfill materials considering the coupling effect of stress-wet-dry cycle as claimed in any one of claims 1 to 9, characterized in that: include: A preprocessing module, used for preprocessing and grouping rockfill material particles to obtain multiple groups of rockfill material samples; A coupling and crushing test module is used to perform stress-wet-dry cycle coupling tests under different dry-wet cycle numbers N and different stresses P on each group of rockfill material samples processed by the pre-processing module, and to perform crushing tests on each group of rockfill material samples that have completed the stress-wet-dry cycle coupling test to obtain their crushing strength σ; thereby obtaining multiple test data; each test data records the corresponding relationship and value of the dry-wet cycle number N, crushing strength σ and stress P; The prediction model building module is used to study the relationship between the crushing strength σ of rockfill samples and stress P under different drying and wetting cycles N according to the test data, and to build a prediction model for the crushing strength of rockfill materials that takes into account the coupling effects of stress and drying and wetting cycles. The crushing strength prediction module is used to use the rockfill crushing strength prediction model considering the coupling effect of stress and dry-wet cycle number to predict the crushing strength of the rockfill material after different dry-wet cycles and different stresses.

Images