Method for quickly determining shear strength of calcareous sand under different stress paths

Abstract

The present application relates to the method for determining the shear strength of calcareous sand under different stress paths quickly, comprising the steps of using the same initial porosity, grading, sample preparation method, saturation method, preparing multiple calcareous sand samples; performing isotropic compression test; obtaining particle size distribution curve, calculating relative breakage rate; again performing isotropic compression test; performing three different stress path tests; recording the deviatoric stress and axial strain in the three different shear processes; obtaining the maximum value of deviatoric stress; obtaining particle size distribution curve, calculating total relative breakage rate; calculating the relative breakage rate of three shear stages; drawing data scatter plot; obtaining fitting parameters, obtaining the fast prediction equation The present application is more suitable for predicting the shear strength of calcareous sand foundation under complex engineering environment; only through simple screening test, the shear strength of calcareous sand can be obtained; it is more suitable for actual engineering; it is more practical; and it provides valuable theoretical basis.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of calcareous sand shear strength calculation, in particular to a method for quickly determining the shear strength of calcareous sand under different stress paths. BACKGROUND

[0002] With the gradual development of China's marine economy, the development capacity of marine resources and the awareness of marine ecological protection are constantly improving, making the number and types of modern marine island engineering in China increasing, and the project scale is also increasing. These marine island engineering mainly uses calcareous sand with rich internal pores, high pore ratio, low particle strength and easy to break as foundation material. The particle breakage phenomenon will have a significant impact on the shear strength of calcareous sand. Therefore, the determination of the shear strength of calcareous sand must consider the influence of the particle breakage effect of calcareous sand.

[0003] At the same time, different marine island engineering often makes calcareous sand in different stress path loading states. For granular soil such as calcareous sand, stress path is also one of the important factors affecting the shear strength of calcareous sand. In addition, stress path will also have an important influence on the particle breakage effect of calcareous sand, making the determination of the shear strength of calcareous sand under different stress paths more complex. Therefore, the study of the shear strength of calcareous sand is crucial to the construction process and safe and stable operation of the built and constructed structures with calcareous sand as foundation.

[0004] At present, the existing technology mainly uses the function relationship between the maximum deviatoric stress (or the maximum principal stress ratio) and the confining pressure to determine the shear strength of calcareous sand, or uses the function relationship between the peak friction angle and the confining pressure established by Duncan and Chang to determine the shear strength of calcareous sand. At the same time, some people also consider the influence of particle breakage on the shear strength of calcareous sand on the basis of the relationship between the peak friction angle and the dilatancy friction angle proposed by Bolton.

[0005] The defects of the existing technology are:

[0006] 1. Since most of the existing technology for determining the shear strength of calcareous sand is proposed under the conventional triaxial compression test path, the influence of stress path on particle breakage and further the influence of stress path on the shear strength of calcareous sand cannot be reflected;

[0007] 2. Since the existing technology for determining the shear strength considering the influence of stress path mainly introduces stress path related parameters (such as stress ratio increment), particle breakage parameters, initial conditions (such as confining pressure), etc., the established influence parameters are too many, the calculation is complex, and it is not conducive to practical application;

[0008] 3. Due to the introduction of the particle crushing parameter determination method in the prior art, the relationship between the test grading curve and the initial grading curve is mainly used to determine the particle crushing amount, but in fact, the calcareous sand sample has produced a certain amount of particle crushing in the consolidation stage. Therefore, when calculating the shear strength, the particle crushing parameter introduced should exclude the influence of particle crushing in the consolidation stage, so as to be more consistent with the actual situation. However, the prior art does not consider the above situation, thereby causing the results to deviate from the actual situation and cannot be corrected.

[0009] 4. In the determination of the particle crushing amount in the method commonly used in the prior art, the particle crushing amount corresponding to the maximum principal stress ratio is mainly used as the benchmark, so that the axial strain corresponding to the end of the test is not uniform. However, in fact, the axial strain is also an important factor affecting the particle crushing effect, so that the particle crushing parameter values in different tests are not uniform, which may cause test errors. SUMMARY

[0010] The present application aims to solve the above problems, and provides a method for quickly determining the shear strength of calcareous sand under different stress paths, which is more suitable for predicting the shear strength of the foundation of calcareous sand in complex engineering environments. The shear strength of calcareous sand can be obtained through simple sieving test, which can greatly reduce the task amount of the test of the engineering personnel. The method is more consistent with the actual engineering. The relative crushing rate is obtained under a specific axial strain condition, which can basically ignore the influence of axial strain on the particle crushing of calcareous sand, further making the test variable acquisition more practical. The method can also provide valuable theoretical basis for the design and safe and stable operation of rockfill dam, and has wide application value.

[0011] To solve the above problems, the technical scheme provided by the present application is as follows:

[0012] The method for quickly determining the shear strength of calcareous sand under different stress paths comprises the following steps:

[0013] S100. Multiple calcareous sand samples are prepared by using the same initial porosity ratio, the same grading, the same sample preparation method, and the same saturation method. Then, isotropic compression tests are carried out under different confining pressures preset by artificial;

[0014] S200. After the isotropic compression test in S100 ends, all the calcareous sand samples are taken out and placed in a ceramic basin for drying and cooling. Then, the particle size distribution curve of each calcareous sand sample under the conditions of the isotropic compression test is obtained, and the relative crushing rate is calculated one by one.

[0015] S300. Again prepare multiple calcareous sand samples with the same initial void ratio as S100, and the same gradation, and the same sample preparation method, and the same saturation method, and then perform again the isotropic compression test under the same confining pressure conditions as S100 for each of the calcareous sand samples;

[0016] Then, after the isotropic compression test under each of the confining pressure conditions is completed, perform three different stress path tests for each of the calcareous sand samples; the stress path tests include a conventional triaxial compression path, a triaxial compression path with constant mean principal stress, and a triaxial compression path with pressure reduction;

[0017] Then, when the axial strain reaches a percentage set by a person, stop the test and record the values of the deviatoric stress and the axial strain during the shearing process of the three different stress path tests under different confining pressure conditions;

[0018] Then, obtain the maximum value of the deviatoric stress of the three different stress path tests;

[0019] S400. After the three different stress path tests in S300 are completed, remove all the calcareous sand samples and place them in a ceramic basin to dry and cool; then obtain the particle size distribution curve of each of the calcareous sand samples under the conditions of the three different stress path tests of the calcareous sand, and calculate the total relative crushing rate one by one;

[0020] S500. According to the test results of S200 and S400, calculate the relative crushing rate of the shearing stage of the three different stress path tests, respectively;

[0021] S600. According to the maximum value of the deviatoric stress of the three different stress path tests obtained in S300, and the relative crushing rate of the shearing stage of the three different stress path tests obtained in S500, draw a scatter plot of the maximum value of the deviatoric stress of the three different stress path tests and the relative crushing rate of the shearing stage of the three different stress path tests in a rectangular coordinate system;

[0022] Then, after obtaining the fitting parameters, obtain a quick prediction equation according to the fitting parameters; the quick prediction equation is the final result of the quick prediction method of the present application.

[0023] Preferably, the preparation of the calcareous sand samples in S100 is performed directly on the instrument base using the sand rain method; the confining pressure conditions are set to no less than 3.

[0024] Preferably, the relative crushing rate in S200 and the total relative crushing rate in S400 are calculated using the relative crushing rate concept of Hardin.

[0025] Preferably, the gradation of the calcareous sand sample in S100 is 1mm-0.5mm;

[0026] The initial void ratio of the calcareous sand sample is 0.9;

[0027] The saturation method of the calcareous sand sample adopts a method of saturation by combining back pressure and carbon dioxide;

[0028] The value of the confining pressure condition of each isotropic compression test is pre-set as 0.3MPa, 0.6MPa, 1.2MPa, and 2.4MPa.

[0029] Preferably, the shear rate of the conventional triaxial compression path in S300 adopts strain control, and the axial displacement increment value is 0.05mm / min;

[0030] The shear rate of the triaxial compression path with constant average principal stress adopts stress control, and the axial stress increment value is 5kPa / min;

[0031] The shear rate of the triaxial compression path with pressure reduction adopts stress control, and the lateral stress increment value is 5kPa / min.

[0032] Preferably, in S300, when the percentage of the axial strain reaches 20%, the test is stopped.

[0033] Preferably, in S500, the relative breakage rate of the shear stage of the three different stress path tests is specifically expressed as follows:

[0034] B rq = B r -B rc

[0035] Wherein: B rq is the relative breakage rate of the shear stage of the three different stress path tests; B r is the total relative breakage rate of the three different stress path tests; B rc is the relative breakage rate under the isotropic compression test.

[0036] Preferably, in S600, the data scatter plot of the maximum value of the deviatoric stress of the three different stress path tests and the relative breakage rate of the shear stage of the three different stress path tests is drawn, and the fitting mode is expressed as follows:

[0037]

[0038] Wherein: q maxis the maximum value of the deviatoric stress of the three different stress path tests, and is the shear strength of the calcareous sand; A is the fitting parameter, and is used for characterizing the shear strength of the calcareous sand when B rq = 50%, the shear strength value corresponding to the calcareous sand sample.

[0039] Preferably, the particle size distribution curve of each of the calcareous sand samples under the condition of the isotropic compression test of the calcareous sand in S200 is obtained by using a sieve shaking method.

[0040] Preferably, the particle size distribution curve of each of the calcareous sand samples under the condition of the three different stress path tests of the calcareous sand in S400 is obtained by using a sieve shaking method.

[0041] Compared with the prior art, the present application has the following advantages:

[0042] 1. Since the present application is not only suitable for determining the shear strength of calcareous sand under the conventional triaxial compression test path, but also can provide reliable results for predicting the shear strength under other different stress paths, the present application is more suitable for predicting the shear strength of the foundation of calcareous sand under complex engineering environment than the prior art;

[0043] 2. Since the prediction method of the present application is simple, only one model parameter is involved, and the model parameter can be easily and reliably obtained through a conventional test, the operation is simple, so that the shear strength of the calcareous sand can be obtained only by a simple sieving test, and the task amount of the test of the engineering personnel can be greatly reduced;

[0044] 3. Since the model variable of the present application is more reasonable, the obtaining process is more operable; by eliminating the influence of the relative breakage rate obtained in the isotropic compression test in the different stress path triaxial compression test, the relative breakage rate in the shearing stage is selected to estimate the shear strength of the calcareous sand, so as to be more consistent with the actual engineering; the relative breakage rate is selected under a specific axial strain condition, the influence of the axial strain on the particle breakage of the calcareous sand can be basically ignored, and the obtaining of the test variable is further more operable;

[0045] 4. The present application can be extended to other granular soil materials such as rockfill material, which considers the shear strength prediction of the rockfill material, and can also provide valuable theoretical basis for the design and safe and stable operation of the rockfill dam, and has wide application value. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a particle size distribution curve under the condition of the isotropic compression test in the embodiment of the present application;

[0047] Figure 2 is a relationship curve between the confining pressure and the relative breakage rate under the condition of the isotropic compression test in the embodiment of the present application;

[0048] Figure 3a Figure 1 is a schematic diagram of the relationship between deviatoric stress and axial strain under the CTC test condition in the embodiment of the present application;

[0049] Figure 3b Figure 2 is a schematic diagram of the relationship between deviatoric stress and axial strain under the TC test condition in the embodiment of the present application;

[0050] Figure 3c Figure 3 is a schematic diagram of the relationship between deviatoric stress and axial strain under the RTC test condition in the embodiment of the present application;

[0051] Figure 4 Figure 4 is a schematic diagram of the relationship between confining pressure and the maximum deviatoric stress under the three different stress path test conditions in the embodiment of the present application

[0052] Figure 5a Figure 5 is a schematic diagram of the particle size distribution curve under the CTC test condition in the embodiment of the present application;

[0053] Figure 5b Figure 6 is a schematic diagram of the particle size distribution curve under the TC test condition in the embodiment of the present application;

[0054] Figure 5c Figure 7 is a schematic diagram of the particle size distribution curve under the RTC test condition in the embodiment of the present application;

[0055] Figure 6 Figure 8 is a schematic diagram of the relationship between confining pressure and total relative crushing rate under the three different stress path test conditions in the embodiment of the present application;

[0056] Figure 7 Figure 9 is a schematic diagram of the relationship between confining pressure and relative crushing rate in the shear stage under the three different stress path test conditions in the embodiment of the present application;

[0057] Figure 8 Figure 10 is a schematic diagram of the relationship between relative crushing rate in the shear stage and the maximum deviatoric stress under the three different stress path test conditions in the embodiment of the present application. DETAILED DESCRIPTION

[0058] The present application will be further illustrated by the following specific embodiments, which are only used to illustrate the present application and not used to limit the scope of the present application, and the modifications of various equivalent forms of the present application made by those skilled in the art after reading the present application all fall within the scope defined by the claims of the present application.

[0059] The method for rapidly determining the shear strength of calcareous sand under different stress paths comprises the following steps:

[0060] S100. Multiple calcareous sand samples were prepared using the same initial void ratio, the same gradation, the same sample preparation method, and the same saturation method; then isotropic compression tests were conducted under different artificially preset confining pressure conditions.

[0061] In this specific embodiment, the calcareous sand sample in S100 is prepared directly on the instrument base using the sand rain method.

[0062] In this specific embodiment, the confining pressure conditions are set to no fewer than three items.

[0063] In this specific embodiment, the gradation of the calcareous sand sample in S100 is 1mm to 0.5mm.

[0064] The initial porosity of the calcareous sand sample was 0.9.

[0065] The saturation method for calcareous sand samples was to use a combination of back pressure and carbon dioxide saturation.

[0066] In this specific embodiment, the confining pressure conditions for each isotropic compression test are preset to 0.3MPa, 0.6MPa, 1.2MPa, and 2.4MPa.

[0067] S200. After the isotropic compression test in S100 is completed, take out all the calcareous sand samples and place them in a ceramic basin to dry and cool. Then, obtain the particle size distribution curve of each calcareous sand sample under the isotropic compression test conditions and calculate the relative breakage rate one by one.

[0068] It is important to note that when removing the sample and placing it in a ceramic basin to dry and cool, you must be extremely careful.

[0069] In this specific embodiment, the relative breakage rate in S200 is calculated using Hardin's concept of relative breakage rate.

[0070] In this specific embodiment, in S200, the particle size distribution curve of each calcareous sand sample under the conditions of isotropic compression test of calcareous sand is obtained by the vibrating sieve method.

[0071] like Figure 1 The figure shows a schematic diagram of the particle size distribution curve under isotropic compression test conditions.

[0072] like Figure 2 The figure shows a schematic diagram of the relationship between confining pressure and relative breakage rate under isotropic compression test.

[0073] S300. Using the same initial void ratio, the same gradation, the same sample preparation method, and the same saturation method as S100, multiple calcareous sand samples are prepared again. Then, each calcareous sand sample is subjected to an isotropic compression test under the same confining pressure conditions as S100.

[0074] In the embodiment, S300 is the same as S100, the gradation of the calcareous sand sample is 1mm-0.5mm; the initial void ratio of the calcareous sand sample is 0.9; the value of the confining pressure condition of each isotropic compression test is preset as 0.3MPa, 0.6MPa, 1.2MPa and 2.4MPa.

[0075] Then, after the isotropic compression test under each confining pressure condition is completed, three different stress path tests are respectively performed on each calcareous sand sample; the stress path test paths include a conventional triaxial compression path (CTC test), a triaxial compression path with constant mean principal stress (TC test) and a triaxial compression path with decompression (RTC test).

[0076] In the embodiment, the shear rate of the conventional triaxial compression path in S300 adopts strain control, and the axial displacement increment value is 0.05mm / min.

[0077] The shear rate of the triaxial compression path with constant mean principal stress adopts stress control, and the axial stress increment value is 5kPa / min.

[0078] The shear rate of the triaxial compression path with decompression adopts stress control, and the lateral stress increment value is 5kPa / min.

[0079] Then, when the axial strain reaches the percentage preset by the artificial, the test is stopped and the values of the deviatoric stress and the axial strain in the shearing process of the three different stress path tests under different confining pressure conditions are recorded.

[0080] In the embodiment, when the percentage of the axial strain reaches 20% in S300, the test is stopped.

[0081] Then, the maximum value of the deviatoric stress of the three different stress path tests is obtained.

[0082] As shown in FIG. 4, it is a deviatoric stress-axial strain relationship curve diagram under the conditions of the three different stress path tests. Figures 3a to 3c As shown in FIG. 5, it is a confining pressure-maximum value of the deviatoric stress relationship curve diagram under the conditions of the three different stress path tests.

[0083] Figure 4

[0084] S400. After the three different stress path tests in S300 are completed, all the calcareous sand samples are taken out and then placed in a ceramic basin for drying and cooling; then the particle size distribution curve of each calcareous sand sample under the conditions of the three different stress path tests of the calcareous sand is obtained, and the total relative crushing rate is calculated one by one.

[0085] ​​It should be noted that the sample is taken out and placed in a ceramic basin to dry and cool down. Be very careful.

[0086] In this embodiment, the total relative breakage rate in S400 is calculated using the concept of relative breakage rate of Hardin.

[0087] In this embodiment, the particle size distribution curve of each calcareous sand sample under the conditions of three different stress path tests of the calcareous sand is obtained by the vibration sieve method in S400.

[0088] As shown in Figures 5a to 5c , it is a schematic diagram of the particle size distribution curve under the conditions of three different stress path tests.

[0089] As shown in Figure 6 , it is a schematic diagram of the relationship between confining pressure and total relative breakage rate under the conditions of three different stress path tests.

[0090] S500. According to the test results of S200 and S400, the relative breakage rate of the shear stage of three different stress path tests is calculated respectively.

[0091] In this embodiment, the relative breakage rate of the shear stage of three different stress path tests in S500 is specifically expressed by formula (1):

[0092] B rq = B r -B rc (1)

[0093] Where: B rq is the relative breakage rate of the shear stage of three different stress path tests; B r is the total relative breakage rate of three different stress path tests; B rc is the relative breakage rate under the isotropic compression test.

[0094] As shown in Figure 7 , it is a schematic diagram of the relationship between confining pressure and relative breakage rate of the shear stage under the conditions of three different stress path tests.

[0095] S600. According to the maximum value of the deviatoric stress of three different stress path tests obtained in S300, and the relative breakage rate of the shear stage of three different stress path tests obtained in S500, a data scatter plot of the maximum value of the deviatoric stress of three different stress path tests and the relative breakage rate of the shear stage of three different stress path tests is drawn in a rectangular coordinate system.

[0096] In this specific embodiment, in S600, a scatter plot of the data relationship between the maximum value of the deviatoric stress and the relative breakage rate of the shear stage of the three different stress path tests is drawn; the fitting method is expressed by equation (2):

[0097]

[0098] Where: q max For shear strength, it is also the maximum value of the deviatoric stress in the three different stress path tests; A is the fitting parameter, used to characterize when B rq =50%, the shear strength value corresponding to the calcareous sand sample.

[0099] like Figure 8 The figure shows a schematic diagram of the relationship between the relative fracture rate and the maximum value of the deviatoric stress during the shear stage under three different stress path test conditions; based on this, the rapid prediction equation is expressed as equation (3):

[0100]

[0101] Then, after obtaining the fitting parameters, a fast prediction equation is obtained based on the fitting parameters; the fast prediction equation is the final result of the fast prediction method of the present invention.

[0102] It should be noted that, through consistency checks of the prediction methods, such as... Figure 8 As shown, its correlation coefficient R 2 The value is >0.95, indicating that the fitting effect meets the needs of general engineering construction.

[0103] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0104] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0105] The above description includes examples of one or more embodiments. Of course, not all possible combinations of components or methods described above will be employed to make or use the embodiments nor will all of

[0106] The specific implementation described above, the purpose of the present application, technical solutions and beneficial effects are further detailed, it should be understood that the above described only for the specific embodiments of the present application, and not used to limit the scope of the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included within the scope of the present application.

Claims

1. A method for rapidly determining the shear strength of calcareous sand under different stress paths, characterized in that: Includes the following steps: S100. Multiple calcareous sand samples were prepared using the same initial void ratio, the same gradation, the same sample preparation method, and the same saturation method; then isotropic compression tests were conducted under different artificially preset confining pressure conditions. S200. After the isotropic compression test described in S100 is completed, take out all the calcareous sand samples and place them in a ceramic basin to dry and cool; then obtain the particle size distribution curve of each of the calcareous sand samples under the conditions of the isotropic compression test, and calculate the relative breakage rate one by one. S300. Using the same initial void ratio as in S100, the same gradation, the same sample preparation method, and the same saturation method, prepare multiple calcareous sand samples again, and then perform isotropic compression tests on each of the calcareous sand samples again under the same confining pressure conditions as in S100. Then, after the isotropic compression test under each of the confining pressure conditions is completed, three different stress path tests are performed on each of the calcareous sand samples; the stress path test path includes a conventional triaxial compression path, a triaxial compression path with a constant mean principal stress, and a decompression triaxial compression path. Then, when the axial strain reaches the preset percentage, the test is stopped and the values ​​of deviatoric stress and axial strain during the shearing process are recorded under different confining pressure conditions for the three different stress paths. Then, the maximum value of the deviatoric stress for the three different stress path tests is obtained; S400. After the three different stress path tests in S300 are completed, take out all the calcareous sand samples and place them in a ceramic basin to dry and cool. Then, obtain the particle size distribution curve of each of the calcareous sand samples under the three different stress path test conditions and calculate the total relative breakage rate one by one. S500. Based on the test results of S200 and S400, calculate the relative breakage rate of the shear stage for the three different stress path tests respectively; S600. Based on the maximum values ​​of the deviatoric stresses obtained in S300 for the three different stress path tests and the relative breakage rates of the shear stage of the three different stress path tests obtained in S500, plot a scatter plot of the data relationship between the maximum values ​​of the deviatoric stresses and the relative breakage rates of the shear stage of the three different stress path tests in a rectangular coordinate system. Then, after obtaining the fitting parameters, a fast prediction equation is obtained based on the fitting parameters; In S600, a scatter plot of the data relating the maximum value of the deviatoric stress to the relative fracture rate during the shear stage of the three different stress path tests is plotted, and the fitting method is expressed by the following formula: Where: q max The shear strength is also the maximum value of the deviatoric stress in the three different stress path tests; A is the fitting parameter used to characterize when B rq =50%, the shear strength value corresponding to the calcareous sand sample; The relative fracture rates of the shear phase in the three different stress path tests described in S500 are expressed by the following formula: B rq =B r -B rc Among them: B rq B represents the relative fracture rate during the shear phase of the three different stress path tests. r B represents the total relative fracture rate for the three different stress path tests. rc The relative breakage rate under the isotropic compression test is denoted as .

2. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to claim 1, characterized in that: The calcareous sand sample described in S100 is prepared directly on the instrument base using the sand rain method. The confining pressure conditions shall be set in no fewer than three items.

3. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to claim 2, characterized in that: The relative breakage rate described in S200 and the total relative breakage rate described in S400 are calculated using Hardin's concept of relative breakage rate.

4. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to claim 3, characterized in that: The gradation of the calcareous sand sample in S100 is 1 mm to 0.5 mm; The initial porosity of the calcareous sand sample is 0.9; The saturation method for the calcareous sand sample is a combination of back pressure and carbon dioxide saturation. The confining pressure conditions for each of the isotropic compression tests are preset to be 0.3 MPa, 0.6 MPa, 1.2 MPa, and 2.4 MPa.

5. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to claim 4, characterized in that: The shear rate of the conventional triaxial compression path described in S300 is controlled by strain, with an axial displacement increment of 0.05 mm / min. The shear rate of the triaxial compression path with a constant average principal stress is stress-controlled, with an axial stress increment of 5 kPa / min. The shear rate of the triaxial compression path for decompression is controlled by stress, with a lateral stress increment value of 5 kPa / min.

6. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to claim 5, characterized in that: In S300, the test is stopped when the percentage of axial strain reaches 20%.

7. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to any one of claims 1 to 6, characterized in that: The particle size distribution curve of each calcareous sand sample obtained under the isotropic compression test conditions using the vibrating sieve method in S200 is obtained.

8. The method for rapidly determining the shear strength of calcareous sand under different stress paths according to claim 7, characterized in that: In S400, the particle size distribution curves of each of the calcareous sand samples were obtained under three different stress path test conditions using the vibrating sieve method.

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