A simple method for calculating the failure time of the interface between a shallow foundation and clay seabed under extreme storm surge action
By measuring foundation roughness and conducting dynamic single-shear tests, combined with wave force calculations, the interface failure under extreme storm surge was simulated, solving the problem of the inability to accurately calculate the interface failure time in existing technologies, and realizing a realistic assessment of foundation stability and support for reinforcement decisions.
Patent Information
- Application Number
- CN202311087754.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-28
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2043-08-28
AI Technical Summary
Existing technologies cannot effectively calculate the failure time at the interface between shallow foundations and the clay seabed under extreme storm surges, resulting in an inability to accurately assess foundation stability. Furthermore, existing research ignores the actual failure at weak interfaces and overestimates the foundation's ability to resist instability.
By measuring foundation roughness, performing dynamic single shear tests, and calculating wave forces, combined with extreme storm surge loads, the interface failure process is simulated, the interface failure time is calculated, and a simple method for interface failure is provided.
It accurately reflects the location of interface damage, precisely assesses foundation stability, avoids overestimating resistance, provides the duration of resistance to extreme storm surges, and provides a basis for reinforcement decisions at the engineering site.
Smart Images
Figure CN117313571B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of geotechnical engineering, and particularly relates to a simple calculation method for interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge. BACKGROUND
[0002] With the continuous expansion of the exploitation and utilization of marine resources, the application of shallow foundations in marine geotechnical engineering is becoming increasingly common. Extreme storm surges are one of the common natural disasters in marine environments, which can produce sustained and changing horizontal loads on shallow foundations on the seabed, have a significant impact on their stability, and may cause disasters such as sliding and overturning of shallow foundations. Therefore, the study of the interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge has significant implications for whether the in-situ shallow foundation needs to be reinforced in advance to resist extreme storm surges.
[0003] Currently, research on the instability and failure of shallow foundations on the seabed mostly focuses on pure soil tests and simulations, simplifying the failure position to the interior of the soil body and ignoring the objective fact that instability and failure of shallow foundations usually occur at the weak interface. However, the pure soil shear strength is greater than the interface shear strength, so this simplification overestimates the ability of shallow foundations to resist instability and failure. Under the action of an extreme storm surge, the soil at the weak interface on a clay seabed accumulates excess pore water pressure, causing the effective stress of the soil at the interface to gradually decrease, leading to the failure of the soil at the interface and further causing the sliding and overturning of the shallow foundation. In addition, existing research is somewhat lacking in simple calculation methods for the interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge, and cannot provide the length of time that a shallow foundation can resist an extreme storm surge. SUMMARY
[0004] The application provides a simple calculation method for the interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge, which can realistically simulate the working conditions in which instability of a shallow foundation occurs at the weak interface between the shallow foundation and the clay seabed, calculate the interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge, provide the length of time that a shallow foundation can resist an extreme storm surge, and determine the stability of an in-situ shallow foundation, providing important feedback on whether the in-situ shallow foundation needs to be reinforced in advance to resist an extreme storm surge.
[0005] The technical scheme of the application is as follows:
[0006] A simple calculation method for the interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge, comprising the following steps:
[0007] 1) The roughness of the shallow foundation R is measured by a roughness meter at the engineering site a , and a structure is prepared according to the roughness of the shallow foundation R a by a dynamic simple shear test;
[0008] 2) Collect seabed clay of shallow foundation laying, carry out dynamic simple shear test, test the initial undrained shear strength S of structure and clay interface u ;
[0009] 3) Take 0.4S u , 0.6S u , 0.8S u , 1S u as the typical amplitude of extreme storm surge load as the benchmark of the initial undrained shear strength S u measured;
[0010] 4) Set up the sine wave of the four typical amplitudes provided in step 3) of extreme storm surge load, carry out dynamic simple shear test to measure the number of cycles N corresponding to the destruction of structure and clay interface;
[0011] 5) According to the number of cycles N of step 4), fit the logarithmic curve of extreme storm surge load amplitude and cycle number N;
[0012] 6) According to the wave force calculation formula and combined with the wave height and wavelength of the predicted extreme storm surge, the amplitude of the extreme storm surge load is calculated;
[0013] 7) The amplitude of the extreme storm surge load is substituted into the logarithmic curve of step 5) to obtain the cycle number N corresponding to the destruction of structure and clay interface;
[0014] 8) According to the cycle number N and the corresponding cycle obtained in step 7), the destruction time of shallow foundation on clay seabed in extreme storm surge is determined.
[0015] Further, in the said simple calculation method of the destruction time of shallow foundation and clay seabed interface under the action of extreme storm surge, the roughness meter in step 1) is a device for measuring and quantifying the roughness of the surface of the target object. The roughness meter evaluates the roughness of the surface by measuring the height difference of the surface; the specific expression of the roughness R a is:
[0016]
[0017] In the formula, n is the number of measurement points, h i represents the height value of the i-th measurement point, and h mean is the average value of the height values of all measurement points.
[0018] Further, in the said simple calculation method of the destruction time of shallow foundation and clay seabed interface under the action of extreme storm surge, the dynamic simple shear test in step 1) is a test for simulating the shear stress environment in actual engineering by applying dynamic load, which is used to evaluate the dynamic shear strength and deformation characteristics of structure and clay interface.
[0019] Further, in the step 2), the interface refers to a layer of weak clay seabed directly contacted with the shallow foundation, and the stability of the shallow foundation on the clay seabed depends on the mechanical properties of the interface.
[0020] Further, in the step 2), the initial undrained shear strength S of the interface between the structure and the clay refers to the undrained shear strength without the influence of cyclic wave loads when the failure position occurs at the interface between the structure and the clay. u Further, in the step 2), the initial undrained shear strength S of the interface between the structure and the clay refers to the undrained shear strength without the influence of cyclic wave loads when the failure position occurs at the interface between the structure and the clay.
[0021] Further, in the step 3), the amplitude refers to the peak value of the extreme storm surge load in the sinusoidal waveform.
[0022] Further, in the step 6), the wave force calculation formula refers to a formula for calculating the amplitude of the extreme storm surge according to the wave height and the wavelength, and the specific expression is as follows:
[0023] P = 0.5 (1 + cos β) (α1 + α2 cos 2 β)yH
[0024]
[0025]
[0026] In the formula, P is the amplitude of the extreme storm surge load, β is the included angle between the wave advancing direction and the normal line of the side surface of the shallow foundation, α1 and α2 are correction coefficients, γ represents the specific gravity of seawater, d is the water depth at the position of the shallow foundation, H and L represent the wave height and the wavelength of the extreme storm surge, respectively.
[0027] The present application has the advantages that the present application provides a simple calculation method for the interface failure time of a shallow foundation and a clay seabed under the action of an extreme storm surge, can truly simulate the working condition that the instability of the shallow foundation occurs at the weak interface between the shallow foundation and the clay seabed, and can calculate the interface failure time of the shallow foundation and the clay seabed under the action of the extreme storm surge, provide the time length that the shallow foundation can resist the extreme storm surge, and determine the stability of the in-situ shallow foundation, thereby providing important feedback for whether the in-situ shallow foundation needs to be reinforced in advance to resist the extreme storm surge. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 The curve showing the variation of the number of cycles N corresponding to the failure of the shallow foundation and clay interface with the amplitude of extreme storm surge. Detailed Implementation
[0029] The present invention will now be described in detail. The following embodiments 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.
[0030] A simplified method for calculating the failure time of the interface between shallow foundations and clay seabed under extreme storm surges includes the following steps:
[0031] 1) The surface roughness R of the shallow foundation was measured using a roughness meter at the engineering site. a The shallow foundation roughness R a The roughness R is 70 μm. a A 70μm metal structure used for dynamic single shear tests;
[0032] 2) Collect seabed clay samples from the shallow foundation to be laid, and conduct dynamic single shear tests. Apply horizontal displacement boundary conditions to the shallow foundation to force failure at the interface between the metal structure and the clay. Measure the initial undrained shear strength S at the interface between the metal structure and the clay. u 20 kPa;
[0033] 3) The initial undrained shear strength S at the interface between the metal structure and the clay u Based on this, 0.4S was selected. u 0.6S u 0.8S u and 1S u Typical amplitudes for extreme storm surge loads are 8 kPa, 12 kPa, 16 kPa, and 20 kPa, respectively.
[0034] 4) Apply the four typical amplitude sinusoidal extreme storm surge loads and carry out dynamic single shear tests. The number of cycles N corresponding to the failure of the structure and clay interface were measured to be 1216, 303, 93, and 29, respectively.
[0035] 5) Based on the number of cycles N measured in step 4), fit the logarithmic curve of the extreme storm surge load amplitude relative to the initial undrained shear strength r versus the number of cycles N, as follows: Figure 1 As shown, the function expression for the fitted curve is:
[0036] N=-184.53-304.25ln(r-0.39);
[0037] 6) According to the wave force formula and the predicted wave height and wavelength of the extreme storm surge, the amplitude of the extreme storm surge load is calculated to be 10 kPa;
[0038] 7) The amplitude of the obtained extreme storm surge load 10 kPa is substituted into the logarithmic curve N = -184.53-304.25ln(r-0.39) fitted in step 5) to obtain the period number N corresponding to the destruction of the structure and clay interface as 487;
[0039] 8) The period number obtained in step 7) is 487, and the corresponding period is 10 s, so the destruction time of the shallow foundation on the clay seabed in the extreme storm surge is determined to be 4870 s.
[0040] The duration of the predicted extreme storm surge is about 3600 s, which is less than the destruction time of the shallow foundation on the clay seabed in the extreme storm surge, which is 4870 s, indicating that the shallow foundation will not fail in this extreme storm surge, meeting the safety requirements.
Claims
1. A simplified method for calculating the failure time of the interface between shallow foundations and clay seabed under extreme storm surges, characterized in that... Includes the following steps: 1) The roughness of shallow foundations was measured on-site using a roughness meter. R a And based on the shallow foundation roughness R a Construct a structure for dynamic single-shear testing; 2) Collect seabed clay samples for the shallow foundation and conduct dynamic single shear tests to measure the initial undrained shear strength S at the structure-clay interface. u ; 3) Using the measured initial undrained shear strength S u Based on this, 0.4S was selected. u 0.6S u 0.8S u and 1S u As a typical amplitude of extreme storm surge load; 4) Set the four typical amplitude sinusoidal extreme storm surge loads provided in step 3), conduct dynamic single shear tests, and measure the number of cycles corresponding to the failure of the structure-clay interface. N ; 5) Based on the number of cycles in step 4). N Fitting the extreme storm surge load amplitude and period number N Logarithmic curve; 6) Calculate the amplitude of the extreme storm surge load based on the wave force calculation formula and the predicted wave height and wavelength. The wave force calculation formula is a formula for calculating the amplitude of the extreme storm surge based on its wave height and wavelength. The specific expression is as follows: In the formula: P This represents the amplitude of extreme storm surge load. β The angle between the direction of wave movement and the normal to the side of the shallow foundation. α 1 and α Both 2 are correction factors. γ Indicates the density of seawater. d The water depth at the location of the shallow foundation. H and L These represent the wave height and wavelength of extreme storm surges, respectively. 7) Substitute the amplitude of the extreme storm surge load into the logarithmic curve of step 5) to obtain the number of cycles corresponding to the failure of the structure-clay interface. N ; 8) Based on the number of cycles obtained in step 7). N The corresponding cycle was used to determine the time of failure of shallow foundations on clay seabeds during extreme storm surges.
2. The simplified calculation method for the failure time of the interface between shallow foundations and clay seabed under extreme storm surges as described in claim 1, characterized in that, In step 1), the roughness meter is a device used to measure and quantify the surface roughness of a target object. The roughness meter evaluates the surface roughness by measuring the height difference of the surface; the roughness... R a The specific expression is: In the formula: n is the number of measurement points, h i h represents the height value of the i-th measurement point. mean It is the average height value of all measurement points.
3. The simplified calculation method for the failure time of the interface between shallow foundations and clay seabed under extreme storm surges as described in claim 1, characterized in that, In step 1), the dynamic single shear test is a test that simulates the shear stress environment in actual engineering by applying dynamic loads, and is used to evaluate the dynamic shear strength and deformation characteristics of the interface between the structure and the clay.
4. The simplified calculation method for the failure time of the interface between shallow foundations and clay seabed under extreme storm surges as described in claim 1, characterized in that, In step 2), the interface refers to a thin layer of seabed clay that is in direct contact with the shallow foundation. The stability of the shallow foundation on the clay seabed depends on the mechanical properties of the interface.
5. The simplified calculation method for the failure time of the interface between shallow foundations and clay seabed under extreme storm surges as described in claim 1, characterized in that, In step 2), the initial undrained shear strength S at the interface between the structure and the clay is... u It refers to the undrained shear strength where the failure occurs at the interface between the structure and the clay and is not affected by cyclic wave loads.
6. The simplified calculation method for the failure time of the interface between shallow foundations and clay seabed under extreme storm surges as described in claim 1, characterized in that, In step 3), amplitude refers to the peak value of the extreme storm surge load of the sinusoidal waveform.