Simplified calculation and analysis methods, devices, and systems for formation strength and settlement

Abstract

This invention discloses a simplified calculation and analysis method, apparatus, and system for foundation strength and settlement, comprising: Step S1, using unsaturated soil as the test object and natural density as the test index, obtaining the total stress intensity incorporating natural density by constructing the relationship between natural density and internal friction angle and cohesion; Step S2, using unsaturated soil as the test object and natural density as the test index, obtaining a stress-strain constitutive model based on natural density; Step S3, using unsaturated soil as the test object and natural density as the test index, calculating the compressive deformation of unsaturated soil incorporating natural density by using the relationship between natural density and deformation modulus and based on the S-P curve of load test. The technical solution of this invention simplifies the analysis of foundation strength and deformation.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology, and in particular relates to a simplified calculation and analysis method, device and system for stratum strength and settlement. Background Technology

[0002] In the field of geotechnical engineering, foundation strength and deformation characteristics are important design indicators affecting the safety of building structures such as buildings, bridges, and tunnels. Existing methods for analyzing the physical and mechanical properties of soil and rock require analysis of the natural physical properties of the strata (moisture content, density, soil particle specific gravity, degree of saturation), determining the limit moisture content and particle composition, and then using laboratory tests to determine soil compression (consolidation) test parameters, subgrade coefficient, static lateral pressure coefficient, shear strength parameters, and permeability coefficient. Finally, the foundation strength and deformation characteristics are evaluated, and subsequent reinforcement or construction measures are implemented.

[0003] The above research process shows that traditional foundation property analysis methods are quite complex, especially when dealing with problems such as slope stability analysis. These methods also require consideration of unsaturated soil mechanical properties such as matrix suction. Indoor testing is difficult, and the large dispersion of soil in the field hinders analytical work. Furthermore, the mechanical properties of unsaturated soil are more complex than the three-phase system of saturated soil. The presence of pores in unsaturated soil results in a force system containing both total stress and matrix suction. However, due to the highly complex nature of matrix suction, its measurement is difficult both indoors and in the field, and research results on matrix suction have not been widely applied in engineering practice. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a simplified calculation and analysis method, device and system for soil strength and settlement. By establishing a physical model, the influence of different natural densities on soil stress-strain relationship, shear strength and deformation characteristics is proposed, so as to simplify the foundation design steps and slope stability study.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A simplified calculation and analysis method for formation strength and settlement includes:

[0007] Step S1: Using unsaturated soil as the test object and natural density as the test index, the total stress intensity introduced by natural density is obtained by constructing the relationship between natural density, internal friction angle, and cohesion.

[0008] Step S2: Using unsaturated soil as the test object and natural density as the test index, obtain a stress-strain constitutive model based on natural density;

[0009] Step S3: Using unsaturated soil as the test object and natural density as the test index, calculate the compression deformation of unsaturated soil with natural density introduced by using the relationship between natural density and deformation modulus and the sp curve based on the load test.

[0010] Preferably, in step S1, the total stress intensity of the introduced natural density is:

[0011] τ f = c(ρ) + σ·tg(φ(ρ)).

[0012] Preferably, in step S2, the stress-strain constitutive model based on natural density is:

[0013]

[0014] Preferably, in step S3, the one-dimensional compression deformation of the strata based on the natural density characteristics is as follows:

[0015]

[0016] The present invention also provides a simplified calculation and analysis device for formation strength and settlement, comprising:

[0017] The first calculation module is used to obtain the total stress intensity by introducing natural density, using unsaturated soil as the test object and natural density as the test index, by constructing the relationship between natural density and internal friction angle and cohesion.

[0018] The second calculation module is used to obtain a stress-strain constitutive model based on natural density, using unsaturated soil as the test object and natural density as the test index.

[0019] The third calculation module is used to calculate the compressive deformation of unsaturated soil with natural density as the test object and natural density as the test index, by using the relationship between natural density and deformation modulus and the sp curve based on the load test.

[0020] As a preferred option, the total stress intensity incorporating natural density is:

[0021] τ f = c(ρ) + σ·tg(φ(ρ)).

[0022] As a preferred option, the stress-strain constitutive model based on natural density is:

[0023]

[0024] As a preferred embodiment, the one-dimensional compression deformation of the strata based on natural density characteristics is as follows:

[0025]

[0026] The present invention also provides a simplified calculation and analysis system for formation strength and settlement, comprising: a memory and a processor, wherein the memory stores a computer program executed by the processor, and the computer program executes a simplified calculation and analysis method for formation strength and settlement when executed by the processor.

[0027] To simplify the analysis of foundation strength and deformation, this invention takes unsaturated soil as the research object and natural density as the core test index. It constructs the relationship between natural density and internal friction angle and cohesion to simplify the foundation strength analysis. It also constructs the relationship between natural density and deformation modulus and simplifies the foundation settlement analysis based on the load test sp curve (s is the settlement and p is the load). Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating the simplified calculation and analysis method for formation strength and settlement according to an embodiment of the present invention.

[0030] Figure 2 The stress-strain curves are for the natural density; where (a) the natural density is 1.97 g / cm³. 3 (b) The natural density is 1.92 g / cm³. 3 (c) The natural density is 1.87 g / cm³. 3 (d) The natural density is 1.82 g / cm³. 3 ;

[0031] Figure 3 The fitted curve of cohesion;

[0032] Figure 4 This is the fitted curve of the internal friction angle;

[0033] Figure 5 Let represent the hyperbolic stress-strain relationship of the soil; where (a) represents the relationship between (σ1-σ2) and ε1, and (b) represents the relationship between ε1 / (σ1-σ2) and ε1.

[0034] Figure 6 Stress-strain curve transformation to account for natural density differences; where (a) the natural density is 1.97 g / cm³. 3 (b) The natural density is 1.92 g / cm³. 3 (c) The natural density is 1.87 g / cm³. 3(d) The natural density is 1.82 g / cm³. 3 . Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1:

[0038] like Figure 1 As shown, this embodiment of the invention provides a simplified calculation and analysis method for formation strength and settlement, including:

[0039] Step S1: Using unsaturated soil as the test object and natural density as the test index, the total stress intensity introduced by natural density is obtained by constructing the relationship between natural density, internal friction angle, and cohesion.

[0040] Step S2: Using unsaturated soil as the test object and natural density as the test index, obtain a stress-strain constitutive model based on natural density;

[0041] Step S3: Using unsaturated soil as the test object and natural density as the test index, calculate the compression deformation of unsaturated soil with natural density introduced by using the relationship between natural density and deformation modulus and the sp curve based on the load test.

[0042] In one embodiment of the present invention, in step S1, the natural density of the parameter analysis test is based on the physical and mechanical properties of in-situ samples, with the confining pressure uniformly controlled at 100 kPa. Based on conventional triaxial compression tests, 16 groups of unsaturated soils with different natural densities were tested for strength and deformation. The natural density (g / cm³) of each group of samples was determined. 3The values ​​were 1.97, 1.96, 1.95, 1.94, 1.93, 1.92, 1.91, 1.90, 1.89, 1.88, 1.87, 1.86, 1.85, 1.84, 1.83, and 1.82, respectively, corresponding to moisture contents of 10.32%, 11.84%, 12.53%, 14.84%, 15.58%, 16.59%, 17.09%, 17.65%, 19.65%, 19.82%, 20.21%, 23.05%, 23.82%, 24.94%, 27.13%, and 28.18%. Each group of samples was left to stand under a confining pressure of 100 kPa for approximately 12 hours to recover to the initial stress state. Then, apply 100 kPa, 150 kPa, 200 kPa, and 250 kPa to the four samples in each group, and shear until failure. Figure 2 As shown.

[0043] Based on cohesion (e.g.) Figure 3 (as shown) and internal friction angle (as shown) Figure 4 The relationship between (as shown) and natural density is used to construct the parameter c(ρ). And write it in the following form:

[0044]

[0045] φ=φ 50 +k φ ·(ρ-ρ 50 (2)

[0046] This allows us to construct a formula for the total stress intensity that incorporates the natural density:

[0047] τ f =c(ρ)+σ·tg(φ(ρ)) (3)

[0048] There are a total of 7 parameters c 50 c 60 c 80 , k c1 k c2 , The parameters have clear meanings. Among them, c 50 This represents the cohesive force at a saturation level of exactly 50%. At a saturation level of 50%, the natural density is 1.94 g / cm³. 3 c 50 =93.31 kPa; c 60 Its natural density is 1.94 g / cm³. 3 (S r Cohesion at 60% (c) 60 =140.56 kPa; c 80This represents the cohesive force when the saturation is exactly 80%. At 80% saturation, the natural density is 1.85 g / cm³. 3 c 80 =75.58kPa; k c1 yes Figure 3 The slope of the left straight line, k c1 =13.95; k c2 yes Figure 3 The slope of the right line, k c2 = -9.83; The internal friction angle when the saturation is exactly 50%. for Figure 4 Slope of the middle line Among them, k c2 , The negative value reflects that the strength of unsaturated soil decreases as the natural density increases.

[0049] As one embodiment of the present invention, in step S2, the classic Duncan-Chang hyperbolic model is as follows: Figure 5 As shown, this is used to study the relationship between deviatoric stress and axial strain. The expression is:

[0050]

[0051] Where a and b are experimental constants. For a conventional triaxial compression test, ε a =ε1.

[0052] In a conventional triaxial compression test, equation (4) can be written as:

[0053]

[0054] The effect of natural density on deviatoric stress and axial strain, such as Figure 6 As shown.

[0055] Taking into account the influence of natural density, the equation takes the following form:

[0056] y a =r1+s1x (6)

[0057]

[0058] Where: y a y b These are functions of parameters a and b in the hyperbolic model, respectively, derived from fitting the natural density; x is the natural density, which has been dimensionless (x = ρ / ρ0, where ρ0 = 1 g / cm³). 3r1, s1, r2, s2, and t2 are all undetermined fitting parameters. The experimental data are fitted with these parameters, and the results are shown in Table 1. Substituting equations (6) and (7) into equation (5), we can obtain the stress-strain constitutive model based on natural density:

[0059]

[0060] Table 1

[0061]

[0062] As one embodiment of the present invention, in step S3, based on the field load test, such as... Figure 6 As shown. The sp relationship also exhibits hyperbolic characteristics, as demonstrated by the Duncan-Chang hyperbolic model:

[0063]

[0064] Where: E t E0 is the deformation modulus; E0 is the initial tangent modulus; p u This refers to the ultimate bearing capacity.

[0065] Formula (7) is the formula for one-dimensional compression deformation of strata:

[0066]

[0067] Where: v is Poisson's ratio; p is the average additional stress acting within the formation thickness range; H is the formation thickness.

[0068] Substituting equation (7) into equation (6) yields the formula for one-dimensional compression deformation of strata based on natural density characteristics:

[0069]

[0070] Traditional foundation strength and deformation design analysis requires the determination of numerous soil physical and mechanical parameters, especially in the stability analysis of unsaturated soil foundations and slopes, where matrix suction is difficult to measure in practice. Therefore, this invention establishes a simplified calculation model for stratum strength and settlement based on natural density indices. This invention offers the following technical advantages:

[0071] 1. A conversion relationship between the shear strength index of unsaturated soil and its natural density is proposed to simplify the strength calculation process and avoid the need to calculate the suction of the soil matrix.

[0072] 2. A hyperbolic constitutive relation of stress-strain in unsaturated soil, influenced by natural density, is proposed.

[0073] 3. A one-dimensional compression deformation formula influenced by natural density is proposed, which is particularly applicable when it is difficult to calculate the matrix suction in unsaturated strata. The foundation compression deformation can be directly predicted from the in-situ soil natural density calculation results.

[0074] Example 2:

[0075] This invention also provides a simplified calculation and analysis device for formation strength and settlement, comprising:

[0076] The first calculation module is used to obtain the total stress intensity by introducing natural density, using unsaturated soil as the test object and natural density as the test index, by constructing the relationship between natural density and internal friction angle and cohesion.

[0077] The second calculation module is used to obtain a stress-strain constitutive model based on natural density, using unsaturated soil as the test object and natural density as the test index.

[0078] The third calculation module is used to calculate the compressive deformation of unsaturated soil with natural density as the test object and natural density as the test index, by using the relationship between natural density and deformation modulus and the sp curve based on the load test.

[0079] As one embodiment of the present invention, the total stress intensity of the natural density is:

[0080] τ f = c(ρ) + σ·tg(φ(ρ)).

[0081] As one embodiment of the present invention, the stress-strain constitutive model based on natural density is as follows:

[0082]

[0083] As one embodiment of the present invention, the one-dimensional compression deformation of strata based on natural density characteristics is as follows:

[0084]

[0085] Example 3:

[0086] This invention also provides a simplified calculation and analysis system for formation strength and settlement, comprising: a memory and a processor, wherein the memory stores a computer program executed by the processor, and the computer program executes a simplified calculation and analysis method for formation strength and settlement when run by the processor.

[0087] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for simplified calculation and analysis of formation strength and subsidence, characterized in that, Comprise: Step S1, taking unsaturated soil as the test object, taking natural density as the test index, obtaining the total stress intensity introducing natural density by constructing the relationship between natural density and internal friction angle and cohesion; Step S2, taking unsaturated soil as the test object, taking natural density as the test index, obtaining the stress-strain constitutive model based on natural density; Step S3, taking unsaturated soil as the test object, taking natural density as the test index, calculating the compression deformation of unsaturated soil introducing natural density through the relationship between natural density and deformation modulus and s-p curve based on load test; In step S1, the total stress intensity introducing natural density is: ； In step S2, the stress-strain constitutive model based on natural density is: ； In step S3, the one-dimensional compression deformation of stratum based on natural density characteristics is: 。 2. A simplified analysis apparatus for calculating formation strength and subsidence, characterized by, Comprise: The first calculation module is used for taking unsaturated soil as the test object, taking natural density as the test index, obtaining the total stress intensity introducing natural density by constructing the relationship between natural density and internal friction angle and cohesion; The second calculation module is used for taking unsaturated soil as the test object, taking natural density as the test index, obtaining the stress-strain constitutive model based on natural density; The third calculation module is used for taking unsaturated soil as the test object, taking natural density as the test index, calculating the compression deformation of unsaturated soil introducing natural density through the relationship between natural density and deformation modulus and s-p curve based on load test; The total stress intensity introducing natural density is: ； The stress-strain constitutive model based on natural density is: ； The one-dimensional compression deformation of stratum based on natural density characteristics is: 。 3. A simplified analysis system for calculating formation strength and subsidence, characterized by, Comprise: Memory and processor, the memory has computer program which is run by the processor and is stored on, the computer program executes the stratum strength and settlement simplified calculation analysis method as claim 1 when being run by the processor.

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