A quantitative determination method for cemented soil material ratio for visual model test

Abstract

The present invention discloses a method for quantitatively determining the proportion of cemented soil materials for visual model testing, the method comprising the following steps: Step 1, completing on-site sampling of rock and soil at the engineering site where a scaled model test is required; Step 2, substituting the values ​​of the specific gravity γ and the internal friction angle #imgabs0# measured in Step 1 into the regression equations Y1 and Y2 corresponding to the specific gravity γ and the internal friction angle #imgabs1#, respectively; Step 3, substituting the values ​​of the quartz sand particle size and the cement-to-stone ratio solved in Step 2 into the regression equation Y3 corresponding to the cohesion c, to complete the solution of the cohesion c. Beneficial effects: It has the advantages of high accuracy and reliability of calculation results, and can provide a scientific basis for the implementation of visual scaled rock and soil model tests. It is obtained by applying direct shear test / triaxial compression, is simple to operate, and is feasible for promotion in actual engineering.

Description

Technical Field

[0001] The invention relates to a method for quantitatively determining the proportion of cemented soil materials, and in particular to a method for quantitatively determining the proportion of cemented soil materials for a visual model test. Background Art

[0002] Currently, infrastructure construction is entering a period of rapid development. The construction of numerous projects inevitably involves the excavation of rock and soil, leading to the emergence of a series of engineering problems, such as rock and soil strength loss, deformation and settlement, and even instability and failure. These problems are often hidden. Therefore, it is crucial to clearly understand the characteristics of rock and soil strength failure and instability and deformation. Scaled model testing is an effective means of addressing these issues.

[0003] For scale model testing, the proper selection of analog materials and their proper proportions are crucial. Existing analog materials are mostly opaque materials such as quartz sand, gypsum, and cement. While these materials meet the requirements of analog theory well and produce relatively reasonable test data, the deformation and seepage characteristics of soils are typically investigated using non-destructive methods such as X-ray diffraction, CT scanning, and nuclear magnetic resonance imaging. These methods are not only expensive and complex, but more importantly, they lack the ability to visualize the experimental process. Therefore, the search for novel alternative materials has become a new approach to testing, and the development of transparent soils has thus begun. International research initially proposed using glass beads or quartz powder as aggregates, combined with a pore fluid of the same refractive index, to create transparent soils. However, these methods suffer from poor transparency and exhibit deformation characteristics significantly different from those of natural soils. However, the use of silica-based materials as aggregates has inspired more scientists. Transparent clays made from amorphous silica powder combined with a mixed mineral oil of the same refractive index have physical and mechanical properties similar to those of natural clays and can simulate some soft clays. According to relevant research, fused quartz sand was used as a skeleton instead of amorphous silica fume, and n-dodecane and 15# white oil were used as pore fluids to simulate natural sand. Triaxial compression tests were conducted to obtain stress-strain curves for the soil, and corresponding formulations were proposed. Furthermore, the use of transparent soil to simulate rock to simulate actual surrounding rock has gradually developed. Amorphous silica fume and mineral oil were combined to create transparent rock masses through molding, vacuum consolidation, and pressure consolidation, and tunnel excavation tests were conducted using these transparent rock masses. Furthermore, new ideas for simulating weak clays using new materials such as NaOH+U10 powder, new AVC copolymers, and precipitated silica have been proposed. Experiments using sucrose solutions and brine mixtures as pore fluids in transparent soils instead of mineral oil have also yielded results. Discussions on transparent soil visualization and transparent soil strength theory are also flourishing.

[0004] In summary, research on transparent sand is relatively mature at this stage. However, research on transparent clay and transparent rock-like materials is still in its early stages. Problems such as insufficient strength of transparent clay and a lack of control over the key physical and mechanical parameters (internal friction angle, cohesion, and soil density) during material configuration require urgent attention. Therefore, considering the combined requirements of transparency and similarity principles, a quantitative method for determining the mix ratio of transparent cementitious soil materials is a topic for those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to realize a visualized model test and to provide a method for quantitatively determining the proportion of cemented soil materials for a visualized model test.

[0006] The present invention provides a method for quantitatively determining the proportion of cemented soil materials for a visual model test, and the method comprises the following steps:

[0007] Step 1: Complete on-site sampling of the rock and soil at the engineering site where the scale model test is required, and use direct shear test / triaxial compression test to complete the gravity γ and internal friction angle and cohesion c three physical and mechanical parameters;

[0008] Step 2: The gravity γ and internal friction angle measured in step 1 are Substitute the values ​​of γ and internal friction angle into The corresponding regression equations Y1 and Y2 are solved simultaneously to obtain the values ​​of the quartz sand particle size X1 and the glue-stone ratio X2. The quartz sand particle size and glue-stone ratio are determined by referring to Table 1. In order to ensure the uniformity and uniformity of the quartz sand material, the quartz sand particle size X1 is rounded, and the glue-stone ratio X2 has a value range of [0, 4].

[0009] Step 3: Substitute the values ​​of the quartz sand particle size and the glue-stone ratio obtained in Step 2 into the regression equation Y3 corresponding to the cohesion c to complete the solution of the cohesion c. The ratio of the cohesion c obtained in Step 3 to the cohesion c of the sample measured by the direct shear test / triaxial compression test in Step 1 is used to determine the similarity ratio of the scale model test size design;

[0010] Table 1 Classification of influencing factors

[0011]

[0012] Step 2: Severe gamma and internal friction angle The corresponding regression equation and various parameters are as follows:

[0013]

[0014]

[0015] Y1—heavy γ, unit kN / m 3 ;

[0016] Y2—Internal friction angle Unit: °;

[0017] Y3—cohesion c, unit kPa;

[0018] X1—quartz sand particle size, in mm, divided into three ranges: 5-3mm, 2-1mm, and 1-0.5mm;

[0019] X2—rubber-stone ratio, unit 1, divided into three values: 10%, 15% and 20%.

[0020] The regression equation and various parameters corresponding to the cohesion c in step 3 are as follows:

[0021]

[0022] Y1—heavy γ, unit kN / m 3 ;

[0023] Y2—Internal friction angle Unit: °;

[0024] Y3—cohesion c, unit kPa;

[0025] X1—quartz sand particle size, in mm, divided into three ranges: 5-3mm, 2-1mm, and 1-0.5mm;

[0026] X2—rubber-stone ratio, unit 1, divided into three values: 10%, 15% and 20%.

[0027] Beneficial effects of the present invention:

[0028] The method for quantitatively determining the proportion of cemented soil materials for visual model testing provided by the present invention comprehensively considers the similarity principle and the requirements of transparency, and provides the numerical values ​​of the quartz sand particle size, the cement-stone ratio, and the similarity ratio through the calculation of the regression equation. It has the advantages of high accuracy and reliability of the calculation results, and can provide a scientific basis for the implementation of visual scaled geotechnical model tests. Parameters such as the internal friction angle, cohesion, and specific gravity of the geotechnical body involved in the engineering site in the mathematical expression can be obtained through on-site survey sampling and the application of direct shear test / triaxial compression. The operation is simple and feasible for promotion in actual engineering projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a flow chart of the method for quantitatively determining the proportion of cemented soil materials described in the present invention. DETAILED DESCRIPTION

[0030] See also Figure 1 As shown:

[0031] The present invention provides a method for quantitatively determining the proportion of cemented soil materials for a visual model test, and the method comprises the following steps:

[0032] Step 1: Complete on-site sampling of the rock and soil at the engineering site where the scale model test is required, and use direct shear test / triaxial compression test to complete the gravity γ and internal friction angle and cohesion c three physical and mechanical parameters;

[0033] Step 2: The gravity γ and internal friction angle measured in step 1 are Substitute the values ​​of γ and internal friction angle into The corresponding regression equations Y1 and Y2 are solved simultaneously to obtain the values ​​of the quartz sand particle size X1 and the glue-stone ratio X2. The quartz sand particle size and glue-stone ratio are determined by referring to Table 1. In order to ensure the uniformity and uniformity of the quartz sand material, the quartz sand particle size X1 is rounded, and the glue-stone ratio X2 has a value range of [0, 4].

[0034] Step 3. Substitute the values ​​of quartz sand particle size and glue-stone ratio obtained in step 2 into the regression equation Y3 corresponding to cohesion c to complete the solution of cohesion c. The ratio of the value of cohesion c obtained in step 3 and the cohesion c of the sample measured by direct shear test / triaxial compression test in step 1 is used to determine the similarity ratio of the scale model test size design.

[0035] Table 1 Classification of influencing factors

[0036]

[0037] Step 2: Severe gamma and internal friction angle The corresponding regression equation and various parameters are as follows:

[0038]

[0039]

[0040] Y1—heavy γ, unit kN / m 3 ;

[0041] Y2—Internal friction angle Unit: °;

[0042] Y3—cohesion c, unit kPa;

[0043] X1—quartz sand particle size, in mm, divided into three ranges: 5-3mm, 2-1mm, and 1-0.5mm;

[0044] X2—rubber-stone ratio, unit 1, divided into three values: 10%, 15% and 20%.

[0045] The regression equation and various parameters corresponding to the cohesion (c) in step 3 are as follows:

[0046]

[0047] Y1—heavy γ, unit kN / m 3 ;

[0048] Y2—Internal friction angle Unit: °;

[0049] Y3—cohesion c, unit kPa;

[0050] X1—quartz sand particle size, in mm, divided into three ranges: 5-3mm, 2-1mm, and 1-0.5mm;

[0051] X2—rubber-stone ratio, unit 1, divided into three values: 10%, 15% and 20%.

[0052] The specific implementation of the present invention is further described in detail below with reference to the accompanying drawings and a certain project as an example.

[0053] According to the preliminary survey report of a tunnel engineering project, the physical and mechanical parameters of the on-site Class IV weak prototype surrounding rock were measured through indoor tests of on-site samples as shown in Table 1: 3 ; Angle of internal friction Cohesion c = 200kPa. According to the material mix ratio determination method, the material density of transparent cementitious soil is γ = 17kN / m 3 , internal friction angle Then Y1 = 17, Y2 = 30. Solving the simultaneous equations using Matlab yields X1 = 1.9951, X2 = 0.1496. Referring to the quartz sand particle size levels in Table 1, the quartz sand particle size ranges from 1 to 0.5 mm, and the interpolated cement-to-cement ratio is 0.748%. Substituting X1 and X2 into equation Y3 yields Y3 = 20.73, indicating an expected material cohesion of 20.73 kPa. Comparing the expected material cohesion with that of the prototype surrounding rock yields a geometric similarity ratio of 9.65:1. The physical and mechanical parameters of the prototype surrounding rock and similar materials are shown in Table 2. The quartz sand particle size X1 and cementation ratio X2 provide quantitative control for the preparation of similar materials, and the geometric similarity ratio of 9.65:1 provides a basis for designing model test dimensions.

[0054] Table 1 Classification of influencing factors

[0055]

[0056] Table 2 Physical and mechanical parameters of prototype surrounding rock and similar materials

[0057]

[0058] The comparison of the main physical and mechanical parameters of the circular surrounding rock and similar materials shows that the gravity γ and internal friction angle The values ​​of the two parameters are the same, meeting the similarity principle requirement. At the same time, the refractive index of the aggregate, binder, and the mixture of n-dodecane and 15# white oil is 1.4585, meeting the transparency requirement.

Claims

1. A method for quantitatively determining the proportion of cemented soil materials for visual model testing, characterized by: The method includes the following steps: Step 1: Complete on-site sampling of the rock and soil at the engineering site where the scale model test is required, and use direct shear test / triaxial compression test to complete the gravity γ and internal friction angle and cohesion c three physical and mechanical parameters; Step 2: The gravity γ and internal friction angle measured in step 1 are Substitute the values ​​of γ and internal friction angle into The corresponding regression equations Y1 and Y2 are solved by simultaneously solving the two equations to obtain the values ​​of quartz sand particle size X1 and glue-stone ratio X2; Severe gamma and internal friction angle The corresponding regression equation and various parameters are as follows: Y1—heavy γ, unit kN / m 3 ; Y2—Internal friction angle Unit degree; X1—quartz sand particle size, unit: mm; X2—rubber-stone ratio; Step 3: Substitute the values ​​of the quartz sand particle size and the glue-stone ratio obtained in Step 2 into the regression equation Y3 corresponding to the cohesion c to complete the solution of the cohesion c. The ratio of the cohesion c obtained in Step 3 to the cohesion c of the sample measured by the direct shear test / triaxial compression test in Step 1 is used to determine the similarity ratio of the scale model test size design; The regression equation and various parameters corresponding to cohesion c are as follows: Y3—cohesion c, unit kPa; X1—quartz sand particle size, unit: mm; X2—rubber-stone ratio.

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