A stability evaluation method based on an envelope surface of bearing capacity of a shallow foundation under wave load

Abstract

The application provides a stability evaluation method based on an envelope surface of a shallow foundation bearing capacity under wave load. The technical scheme is: collecting soil samples on the engineering site and carrying out test calibration of soil parameters; establishing a three-dimensional numerical model based on a modified Cambridge model and calculating the initial bearing capacity of the shallow foundation; selecting and applying representative amplitudes of wave load to the shallow foundation to obtain the horizontal-moment bearing capacity envelope surface under different amplitudes of wave load; calculating the actual horizontal and moment loads borne by the shallow foundation according to the on-site wave load and determining whether the actual horizontal and moment loads are below all the horizontal-moment bearing capacity envelope surfaces to determine the stability of the shallow foundation. The application can truly simulate the working condition of the shallow foundation bearing the combined action of horizontal and moment cyclic loads in the marine environment, calculate the bearing capacity envelope surface of the shallow foundation under different amplitudes of wave load, determine whether the shallow foundation has a safety hazard, and provide a reference for whether reinforcement treatment measures need to be taken for the in-situ shallow foundation.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology, specifically relating to a stability assessment method based on the envelope of the bearing capacity of shallow foundations under wave load. Background Technology

[0002] In the field of marine engineering, assessing the stability of shallow foundations has always been a significant and challenging task. In the turbulent marine environment, wave loads have a significant impact on the load-bearing capacity and stability of shallow foundations. However, current methods for assessing the stability of shallow foundations fail to adequately consider the variability of wave loads and the diversity of horizontal and bending moment loads that shallow foundations experience in the marine environment, resulting in unsatisfactory accuracy and reliability of the assessment results.

[0003] In existing technologies, some methods show that the bearing capacity of shallow foundations gradually increases under consolidation, neglecting the gradual decrease in effective soil stress and bearing capacity caused by the continuous accumulation of excess pore water pressure under wave loads. Other methods focus only on bearing capacity calculations under unidirectional wave loads, ignoring the combined effects of different wave conditions and marine environmental variations on the stability of shallow foundations. Summary of the Invention

[0004] This invention provides a stability assessment method based on the bearing capacity envelope of shallow foundations under wave loads. It can realistically simulate the working conditions of shallow foundations subjected to the combined action of horizontal and bending moment cyclic loads in a marine environment, and calculate the bearing capacity envelope of shallow foundations under wave loads of different amplitudes. This method can determine whether there are any safety hazards in the shallow foundations and provide an important reference for whether reinforcement measures need to be taken for the shallow foundations in place on the engineering site, thereby improving the reliability and safety of shallow foundation design and engineering implementation.

[0005] The technical solution of the present invention is as follows:

[0006] A stability assessment method based on the bearing capacity envelope of shallow foundations under wave loading includes the following steps:

[0007] S1: Collect soil samples from shallow foundation service projects and conduct triaxial and consolidation tests to calibrate soil parameters;

[0008] S2: Based on the soil parameters provided by S1, a three-dimensional numerical model of the seabed is established by modifying the Cambridge model. A three-dimensional numerical model of the shallow foundation is constructed according to the actual size of the shallow foundation and placed on the three-dimensional numerical model of the seabed.

[0009] S3: Calculate the initial single bearing load and initial horizontal-bending moment bearing capacity envelope of the shallow foundation using the three-dimensional numerical model constructed in S2;

[0010] S4: Based on the initial single bearing load calculated in S3, select 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 times the initial single bearing load as representative amplitudes of wave load;

[0011] S5: Apply the representative amplitude selected in S4 to the shallow foundation of the three-dimensional numerical model to obtain the horizontal-bending moment bearing capacity envelope under wave loads of different amplitudes;

[0012] S6: Calculate the actual horizontal and bending moment loads borne by the shallow foundation based on the wave height and wavelength parameters measured by the wave buoy and the wave load formula;

[0013] S7: Determine whether the actual horizontal and bending moment loads borne by the shallow foundation are below all horizontal-bending moment bearing capacity envelopes; if “yes”, the bearing capacity of the shallow foundation is considered to be in a safe state; if “no”, the bearing capacity of the shallow foundation is considered to have a safety hazard and reinforcement measures need to be taken for the shallow foundation.

[0014] Furthermore, in the stability assessment method based on the bearing capacity envelope of shallow foundations under wave load, the soil parameters in step S1 include void ratio e, Poisson's ratio μ, compression index λ, expansion index κ, and critical stress ratio M.

[0015] Furthermore, in the stability assessment method based on the bearing capacity envelope of shallow foundations under wave load, the modified Cambridge model in step S2 refers to a constitutive model used to describe the elastoplastic behavior of saturated clay. It considers the deformation capacity of the soil under cyclic wave load to describe the changing trend of the horizontal-bending moment bearing capacity envelope of clay seabed shallow foundations under cyclic wave load.

[0016] Furthermore, in the stability assessment method based on the envelope of shallow foundation bearing capacity under wave load, the initial single bearing capacity of the shallow foundation in step S3 includes the horizontal and bending moment bearing capacity after the shallow foundation is positioned on the seabed and is not affected by wave load.

[0017] Furthermore, the stability assessment method based on the bearing capacity envelope of shallow foundations under wave loads uses the horizontal-bending moment bearing capacity envelope as the envelope fitted by the limit of the horizontal-bending moment external force that the shallow foundation can withstand when different proportions of horizontal-bending moment loads are applied.

[0018] Furthermore, in the stability assessment method based on the envelope of shallow foundation bearing capacity under wave load, the wave buoy in step S6 refers to a tool that collects its own floating signal at a specific frequency, processes and calculates the signal to obtain wave parameters.

[0019] Furthermore, in the stability assessment method based on the bearing capacity envelope of shallow foundations under wave load, the wave load formula in step S6 refers to a formula for calculating the amplitude of waves based on their wave height and wavelength parameters. The specific expression is as follows:

[0020] P = 0.5(1+cosβ)(α1+α2cos 2 β)γH

[0021]

[0022]

[0023] In the formula: P is the amplitude of the extreme storm surge load, β is the angle between the wave advance direction and the normal to the side of the shallow foundation, α1 and α2 are correction coefficients, γ represents the specific weight of seawater, d is the water depth at the location of the shallow foundation, and H and L represent the wave height and wavelength of the extreme storm surge, respectively.

[0024] Furthermore, in the stability assessment method based on the bearing capacity envelope of shallow foundations under wave load, the reinforcement measures in step S7 refer to using an anchoring system to connect the shallow foundation to the seabed to improve the overall stability of the shallow foundation.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. This invention can realistically simulate the working conditions of shallow foundations subjected to the combined action of horizontal and bending moment cyclic loads in a marine environment, and calculates the bearing capacity envelope of shallow foundations under wave loads of different amplitudes, determining whether there are any safety hazards in the shallow foundations. It provides an important reference for whether reinforcement measures need to be taken for the shallow foundations in place on the engineering site, and improves the reliability and safety of shallow foundation design and engineering implementation.

[0027] 2. This invention comprehensively considers the changes in horizontal and bending moment bearing capacity under different wave conditions, and can obtain the horizontal-bending moment bearing capacity envelope under wave loads of different amplitudes, and accurately assess the stability of shallow foundations.

[0028] 3. This invention comprehensively considers multiple key factors, such as wave parameters, foundation structure form, soil material properties, and marine environmental characteristics, which greatly improves the comprehensiveness and reliability of the assessment. Attached Figure Description

[0029] Figure 1 This is a graph showing the variation trend of the normalized bearing capacity envelope of shallow foundations with different values ​​of wave load amplitude. Detailed Implementation

[0030] The present invention will now be described in detail. The following examples will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0031] A stability assessment method based on the bearing capacity envelope of shallow foundations under wave loading includes the following steps:

[0032] S1: Collect soil samples from the shallow foundation service site, conduct triaxial and consolidation tests to calibrate the soil parameters. The results show that the void ratio e is 0.87, Poisson's ratio μ is 0.37, compression index λ is 0.13, expansion index κ is 0.03, and critical stress ratio M is 1.4.

[0033] S2: Based on the soil parameters provided by S1, a three-dimensional numerical model of the seabed is established by modifying the Cambridge model. The shallow foundation is simplified into a cuboid with a length, width and height of 10m, 10m and 5m respectively, and the material is steel. The three-dimensional numerical model of the shallow foundation is constructed in this way and placed on the three-dimensional numerical model of the seabed.

[0034] S3: Apply displacement boundary conditions to the shallow foundation in the 3D numerical model constructed in S2, forcing the shallow foundation to fail with the contacting seabed soil. The initial horizontal bearing capacity of the shallow foundation is calculated to be 25 kN, and the initial bending moment bearing capacity is 40 kN·m. Plot the initial horizontal-bending moment bearing capacity envelope surface. Figure 1 The outermost envelope;

[0035] S4: Based on the initial single bearing load calculated in S3, select 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 times the initial single bearing load as representative amplitudes of wave loads. The horizontal load amplitudes are 2.5kN, 5kN, 7.5kN, 10kN, 12.5kN, 15kN and 17.5kN, respectively, and the bending moment load amplitudes are 4kN·m, 8kN·m, 12kN·m, 16kN·m, 20kN·m, 24kN·m and 28kN·m, respectively.

[0036] S5: Apply the representative amplitude selected in S4 to the shallow foundation to obtain the horizontal-bending moment bearing capacity envelope under wave loads of different amplitudes, such as... Figure 1 As shown, where r cy The wave load represents the proportion of the horizontal and bending moment load amplitudes caused by the wave load on the shallow foundation to the initial single bearing capacity. The arrow direction indicates the envelope of the shallow foundation bearing capacity under different load amplitudes; as r... cyAs the value increases, the bearing capacity envelope of the shallow foundation gradually stabilizes at a fixed position, which is considered to be the minimum case of the bearing capacity envelope of the shallow foundation.

[0037] S6: Based on the wave height and wavelength parameters measured by the wave buoy and the wave load formula, the actual horizontal and bending moment loads borne by the shallow foundation are calculated to be 7.5 kN and 16 kN·m, respectively. The obtained horizontal and bending moment loads are normalized by dividing them by the initial horizontal bearing capacity of 25 kN and the initial bending moment bearing capacity of 40 kN·m, respectively, yielding corresponding normalization coefficients of 0.3 and 0.4. This allows us to obtain the actual positions of the horizontal and bending moment loads within the bearing capacity envelope. (See...) Figure 1 The solid black rhombus in the middle indicates its location;

[0038] S7: If the actual horizontal and bending moment loads borne by the shallow foundation are below all horizontal-bending moment bearing capacity envelopes, the bearing capacity of the shallow foundation is determined to be in a safe state and meets the safety requirements. Therefore, no reinforcement measures are required for the shallow foundation at this time.

Claims

1. A stability assessment method based on the bearing capacity envelope of shallow foundations under wave load, characterized in that, Includes the following steps: S1: Collect soil samples from shallow foundation service projects and conduct triaxial and consolidation tests to calibrate soil parameters; S2: Based on the soil parameters provided by S1, a three-dimensional numerical model of the seabed is established by modifying the Cambridge model. A three-dimensional numerical model of the shallow foundation is constructed according to the actual size of the shallow foundation and placed on the three-dimensional numerical model of the seabed. S3: Calculate the initial single bearing load and initial horizontal-bending moment bearing capacity envelope of the shallow foundation using the three-dimensional numerical model constructed in S2; S4: Based on the initial single bearing load calculated in S3, select 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 times the initial single bearing load as representative amplitudes of wave load; S5: Apply the representative amplitude selected in S4 to the shallow foundation of the three-dimensional numerical model to obtain the horizontal-bending moment bearing capacity envelope under wave loads of different amplitudes; S6: Calculate the actual horizontal and bending moment loads borne by the shallow foundation based on the wave height and wavelength parameters measured by the wave buoy and the wave load formula; the wave load formula is a formula for calculating the amplitude of waves based on the wave height and wavelength parameters, and its specific expression is as follows: In the formula: P is the amplitude of the extreme storm surge load, β is the angle between the wave advance direction and the normal of the shallow foundation side, α1 and α2 are correction coefficients, γ represents the specific weight of seawater, d is the water depth at the location of the shallow foundation, and H and L represent the wave height and wavelength of the extreme storm surge, respectively. S7: Determine whether the actual horizontal and bending moment loads borne by the shallow foundation are below all horizontal-bending moment bearing capacity envelopes; if "yes", the bearing capacity of the shallow foundation is considered to be in a safe state; if "no", the bearing capacity of the shallow foundation is considered to have a safety hazard and reinforcement measures need to be taken for the shallow foundation.

2. The stability assessment method based on the bearing capacity envelope of shallow foundations under wave load as described in claim 1, characterized in that, The soil parameters in step S1 include void ratio e, Poisson's ratio μ, compression index λ, expansion index κ, and critical stress ratio M.

3. The stability assessment method based on the envelope of shallow foundation bearing capacity under wave load as described in claim 1, characterized in that, The modified Cambridge model in step S2 is a constitutive model used to describe the elastoplastic behavior of saturated clay. It considers the deformation capacity of the soil under cyclic wave loads to describe the changing trend of the horizontal-bending moment bearing capacity envelope of clay seabed shallow foundations under cyclic wave loads.

4. The stability assessment method based on the bearing capacity envelope of shallow foundations under wave load as described in claim 1, characterized in that, The initial single bearing capacity of the shallow foundation in step S3 includes the horizontal and bending moment bearing capacity after the shallow foundation is placed on the seabed and is not affected by wave loads.

5. The stability assessment method based on the bearing capacity envelope of shallow foundations under wave load as described in claim 1, characterized in that, The horizontal-bending moment bearing capacity envelope is the envelope fitted by the limit of the horizontal-bending moment external force that the shallow foundation can withstand when different proportions of horizontal-bending moment loads are applied.

6. The stability assessment method based on the bearing capacity envelope of shallow foundations under wave load as described in claim 1, characterized in that, The wave buoy in step S6 refers to a tool that collects its own floating signal at a specific frequency, processes the signal, and obtains wave parameters.

7. The stability assessment method based on the bearing capacity envelope of shallow foundations under wave load as described in claim 1, characterized in that, The reinforcement measures in step S7 refer to using an anchoring system to connect the shallow foundation to the seabed in order to improve the overall stability of the shallow foundation.

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