A method for predicting the amount of crustal erosion under extreme sea conditions

Abstract

The invention discloses a method for predicting the erosion of a hard crust layer under extreme sea conditions, which belongs to the technical field of predicting the erosion of a hard crust layer and is used for predicting the erosion of a hard crust layer. The method comprises determining the water pressure growth rate of the surface soil of the hard crust layer caused by waves according to the water pressure growth coefficient, and sequentially calculating the growth rate of the destructive force of the water pressure inside the surface soil of the hard crust layer on the soil particle aggregates, the resistance to destructive force of the soil particle aggregates, the time required for the erosion of the soil particle aggregates, the number of soil particle aggregate layers eroded by continuous wave action, and the total erosion of the hard crust layer by continuous wave action. The invention has important reference value for determining the erosion of the seabed and guiding the design of marine engineering, and the invention has the advantages of strong versatility and reliable results.

Description

Technical Field

[0001] The invention discloses a method for predicting the amount of hard crust erosion under extreme sea conditions, and belongs to the technical field of prediction of the amount of hard crust erosion. Background Art

[0002] The hard crust is a unique geological structure developed on the seabed, and its formation is related to river diversion, sedimentation, waves, etc. The hard crust is often strong, the bonding strength between particles is also high, and the ability to resist erosion is strong. This feature makes the traditional river and wave soft soil erosion theory no longer applicable in determining the erosion of the hard crust. The existing technology lacks a method that can quickly calculate the prediction of the erosion amount of the hard crust. Summary of the invention

[0003] The purpose of the present invention is to provide a method for predicting the amount of hard crust erosion under extreme sea conditions, so as to solve the problem that the traditional river and wave soft soil erosion theory is no longer applicable in determining the erosion of the hard crust, and the prior art lacks a method that can quickly calculate the prediction of the amount of hard crust erosion.

[0004] A method for predicting the amount of hard crust erosion under extreme sea conditions determines the water pressure growth rate inside the surface soil of the hard crust caused by waves according to the water pressure growth coefficient, and sequentially calculates the growth rate of the destructive force of the water pressure inside the surface soil of the hard crust on soil particle aggregates, the resistance to destructive force of soil particle aggregates, the time required for erosion of soil particle aggregates, the number of soil particle aggregate layers eroded by continuous wave action, and the total erosion amount of the hard crust under continuous wave action.

[0005] Calculating the water pressure growth coefficient includes setting up an experimental environment, obtaining data on changes in water pressure inside the soil over time, drawing a circulation ratio-water pressure ratio curve with the circulation ratio as the horizontal axis and the water pressure ratio as the vertical axis, and fitting the water pressure ratio function using the least squares method based on the circulation ratio-water pressure ratio curve to obtain the water pressure growth coefficient.

[0006] Setting up the experimental environment includes obtaining the original soil sample retrieved by the drilling rig, conducting a dynamic triaxial test, setting the consolidation ratio to 1.0, and applying a confining pressure of for:

[0007] ; ;

[0008] The dynamic load is applied in the form of a sinusoidal load, and the magnitude of the sinusoidal load is , the period is , is the density of seawater, is the acceleration due to gravity, is the water depth at the crust layer, is a hyperbolic function, It’s the wave height, is the wavelength.

[0009] The circulation ratio is , water pressure ratio for:

[0010] ;

[0011] In the formula, is the number of loads in a single cycle, is the number of cyclic loads when the soil completely loses its strength, For a certain water pressure, It is the water pressure when the soil completely loses its strength.

[0012] The fitting function of water pressure ratio is:

[0013] ;

[0014] In the formula, , are two water pressure growth coefficients, is an empirical function.

[0015] Determine the water pressure growth rate inside the hard crust surface soil caused by waves based on the water pressure growth coefficient for:

[0016] ;

[0017] ;

[0018] ;

[0019] In the formula, It is the density of the original soil sample of the hard crust layer tested using the ring knife method. It is the maximum density of the original soil sample of the hard crust layer tested using the ring knife method. is the wave period, is the relative density of the original soil sample in the hard crust layer, is the reference depth, It is the median particle size of soil particles in the hard crust layer.

[0020] Calculate the growth rate of the destructive force of the internal water pressure of the surface soil of the hard crust on the soil particle aggregates for:

[0021] ;

[0022] Calculate the resistance of soil particle aggregates to destruction for:

[0023] ;

[0024] In the formula, It is the particle density of soil particles measured by the pycnometer method.

[0025] Calculate the time required for soil particle aggregates to erode for:

[0026] ;

[0027] Calculate the number of aggregate layers of soil particles eroded by continuous wave action for:

[0028] ;

[0029] In the formula, It is the time that the wave continues to act.

[0030] Calculate the total erosion of the hard crust due to continuous wave action for:

[0031] .

[0032] Before calculating the water pressure growth factor, perform the following steps:

[0033] Determine the hydrodynamic parameters of the hard crust under extreme sea conditions. The hydrodynamic parameters include , , , and , the original soil samples were taken from the hard crust layer using a drill and transported back to the laboratory for testing using the pycnometer method. The original soil samples were dried and crushed, and the sieving method and moisture method were used to test the .

[0034] Compared with the prior art, the present invention has the following beneficial effects: the present invention has important reference value for determining the amount of seabed erosion and guiding marine engineering design, and the present invention has the advantages of strong versatility and reliable results. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] A method for predicting the amount of hard crust erosion under extreme sea conditions determines the water pressure growth rate inside the surface soil of the hard crust caused by waves according to the water pressure growth coefficient, and sequentially calculates the growth rate of the destructive force of the water pressure inside the surface soil of the hard crust on soil particle aggregates, the resistance to destructive force of soil particle aggregates, the time required for erosion of soil particle aggregates, the number of soil particle aggregate layers eroded by continuous wave action, and the total erosion amount of the hard crust under continuous wave action.

[0037] Calculating the water pressure growth coefficient includes setting up an experimental environment, obtaining data on changes in water pressure inside the soil over time, drawing a circulation ratio-water pressure ratio curve with the circulation ratio as the horizontal axis and the water pressure ratio as the vertical axis, and fitting the water pressure ratio function using the least squares method based on the circulation ratio-water pressure ratio curve to obtain the water pressure growth coefficient.

[0038] Setting up the experimental environment includes obtaining the original soil sample retrieved by the drilling rig, conducting a dynamic triaxial test, setting the consolidation ratio to 1.0, and applying a confining pressure of for:

[0039] ; ;

[0040] The dynamic load is applied in the form of a sinusoidal load, and the magnitude of the sinusoidal load is , the period is , is the density of seawater, is the acceleration due to gravity, is the water depth at the crust layer, is a hyperbolic function, It’s the wave height, is the wavelength.

[0041] The circulation ratio is , water pressure ratio for:

[0042] ;

[0043] In the formula, is the number of loads in a single cycle, is the number of cyclic loads when the soil completely loses its strength, For a certain water pressure, It is the water pressure when the soil completely loses its strength.

[0044] The fitting function of water pressure ratio is:

[0045] ;

[0046] In the formula, , are two water pressure growth coefficients, is an empirical function.

[0047] Determine the water pressure growth rate inside the hard crust surface soil caused by waves based on the water pressure growth coefficient for:

[0048] ;

[0049] ;

[0050] ;

[0051] In the formula, It is the density of the original soil sample of the hard crust layer tested using the ring knife method. It is the maximum density of the original soil sample of the hard crust layer tested using the ring knife method. is the wave period, is the relative density of the original soil sample in the hard crust layer, is the reference depth, It is the median particle size of soil particles in the hard crust layer.

[0052] Calculate the growth rate of the destructive force of the internal water pressure of the surface soil of the hard crust on the soil particle aggregates for:

[0053] ;

[0054] Calculate the resistance of soil particle aggregates to destruction for:

[0055] ;

[0056] In the formula, It is the particle density of soil particles measured by the pycnometer method.

[0057] Calculate the time required for soil particle aggregates to erode for:

[0058] ;

[0059] Calculate the number of aggregate layers of soil particles eroded by continuous wave action for:

[0060] ;

[0061] In the formula, It is the time that the wave continues to act.

[0062] Calculate the total erosion of the hard crust due to continuous wave action for:

[0063] .

[0064] Before calculating the water pressure growth factor, perform the following steps:

[0065] Determine the hydrodynamic parameters of the hard crust under extreme sea conditions. The hydrodynamic parameters include , , , and , the original soil samples were taken from the hard crust layer using a drill and transported back to the laboratory for testing using the pycnometer method. The original soil samples were dried and crushed, and the sieving method and moisture method were used to test the .

[0066] The working principle of the present invention is that due to the high strength of the hard crust soil, the wave cyclic shear stress cannot directly cause the erosion of the hard crust soil. Instead, the wave cyclic load causes the water pressure inside the soil particle aggregates of the surface soil of the hard crust layer to increase, so that the soil strength is completely lost and then erosion is caused. Through the principle of mechanical balance between water pressure and soil particles, the destruction time of soil particle aggregates is established, and the number of layers of eroded soil particle aggregates is further calculated, and finally the total erosion amount is obtained.

[0067] The present invention conducted two groups of experiments. The first group of experiments selected sea area A where a hard crust layer was developed. In addition, cold currents in winter each year easily induce strong winds and waves, causing erosion of the hard crust layer in the sea area, affecting the safety of marine engineering. In order to determine the erosion amount of the hard crust layer, the method of the present invention was used for prediction.

[0068] According to the empirical values ​​of hydrodynamic parameters under local extreme sea conditions, the 4.2m, 51.5m, 6.5s, 4.1h; using the water depth measurement tool, the measured 10.4m. OK The original soil samples were taken from the hard crust layer using a drill and transported back to the laboratory for testing using the pycnometer method. 2750kg / m 3 The original soil samples obtained by the drilling rig were transported back to the laboratory, dried, crushed, and tested using the screening method and moisture method. It is 0.11mm.

[0069] The original soil samples retrieved by the drilling rig were subjected to dynamic triaxial tests in the laboratory with a consolidation ratio of 1.0. is 106.6kPa, and the dynamic load is a sinusoidal load. 11.2 kPa, The test results are 6.5s, and the water pressure of the excavated body changes with time. is the horizontal axis, As the vertical axis, draw the relationship curve between circulation ratio and water pressure ratio. Using the least squares method to fit, we get 0.430 It is 0.176.

[0070] The original soil samples of the hard crust layer retrieved by the drilling rig were tested using the ring knife method. 1701kg / m 3 , and then use the standard compaction test to test 1982kg / m 3 , then confirm is 0.86, and the water pressure growth rate of the hard crust soil caused by waves under extreme sea conditions is determined to be kPa / s, for kN / s, for kN, is 267.1s, is 55, is 1.8cm.

[0071] The second group of experiments selected the B coastal zone. There is a layer of hard plate sand with high strength, namely the hard crust layer, in the B coastal zone. The strong typhoons that prevail every year cause certain erosion of the hard crust layer in the coastal zone, causing the beach surface to continue to decline and the water depth to increase. As the hard crust layer continues to recede, engineering facilities such as roads in the coastal zone are threatened to a certain extent. In order to clarify the erosion amount of the hard crust layer by each strong typhoon, the method of the present invention is used for prediction.

[0072] According to the typical data of local meteorological and hydrological data, the hard crust layer under strong typhoon 3.6m, 43.1m, 6.1s, 3.2h; using water depth measurement tools, the measured 8.3m. OK The original soil samples were taken from the hard crust layer using a drill and transported back to the laboratory for testing using the pycnometer method. 2755kg / m 3 The original soil samples obtained by the drilling rig were transported back to the laboratory, dried, crushed, and tested using the screening method and moisture method. It is 0.17mm.

[0073] The original soil samples retrieved by the drilling rig were subjected to dynamic triaxial tests in the laboratory with a consolidation ratio of 1.0. is 85.1kPa, and the dynamic load is a sinusoidal load. is 10.1 kPa, The test results show that the water pressure of the excavated body changes with time. is the horizontal axis, As the vertical axis, draw the relationship curve between circulation ratio and water pressure ratio. Using the least squares method to fit, we get is 0.425, It is 0.178.

[0074] The original soil samples of the hard crust layer retrieved by the drilling rig were tested using the ring knife method. 1722kg / m 3 , and then use the standard compaction test to test 1984kg / m 3 , is 0.87, which determines the water pressure growth rate of the hard crust soil caused by waves under extreme sea conditions kPa / s, for kN / s, for kN, is 159.4s, is 72, is 3.7cm.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for predicting the amount of crustal erosion under extreme sea conditions, characterized in that: The water pressure growth rate inside the surface soil of the hard crust layer caused by waves is determined according to the water pressure growth coefficient, and the growth rate of the destructive force of the water pressure inside the surface soil of the hard crust layer on the soil particle aggregates, the resistance to destructive force of the soil particle aggregates, the time required for the erosion of the soil particle aggregates, the number of soil particle aggregate layers eroded by the continuous action of waves, and the total erosion amount of the hard crust layer due to the continuous action of waves are calculated in sequence; Calculating the water pressure growth coefficient includes setting up an experimental environment, obtaining the data of the change of water pressure inside the soil over time, drawing a relationship curve between the circulation ratio and the water pressure ratio with the circulation ratio as the horizontal coordinate and the water pressure ratio as the vertical coordinate, and fitting the water pressure ratio function with the least square method according to the relationship curve between the circulation ratio and the water pressure ratio to obtain the water pressure growth coefficient; Setting up the experimental environment includes obtaining the original soil sample retrieved by the drilling rig, conducting a dynamic triaxial test, setting the consolidation ratio to 1.0, and applying a confining pressure of for: ； ； The dynamic load is applied in the form of a sinusoidal load, and the magnitude of the sinusoidal load is , the period is , is the density of seawater, is the acceleration due to gravity, is the water depth at the crust layer, is a hyperbolic function, It’s the wave height, is the wavelength; The circulation ratio is , water pressure ratio for: ； In the formula, is the number of loads in a single cycle, is the number of cyclic loads when the soil completely loses its strength, For a certain water pressure, It is the water pressure when the soil loses its strength completely; The fitting function of water pressure ratio is: ； In the formula, , are two water pressure growth coefficients, is an empirical function; Determine the water pressure growth rate inside the hard crust surface soil caused by waves based on the water pressure growth coefficient for: ； ； ； In the formula, It is the density of the original soil sample of the hard crust layer tested using the ring knife method. It is the maximum density of the original soil sample of the hard crust layer tested using the ring knife method. is the wave period, is the relative density of the original soil sample in the hard crust layer, is the reference depth, is the median particle size of soil particles in the hard crust layer; Calculate the growth rate of the destructive force of the internal water pressure of the surface soil of the hard crust on the soil particle aggregates for: ； Calculate the resistance of soil particle aggregates to destruction for: ； In the formula, is the particle density of soil particles measured by the pycnometer method; Calculate the time required for soil particle aggregates to erode for: ； Calculate the number of aggregate layers of soil particles eroded by continuous wave action for: ； In the formula, is the duration of the wave action; Calculate the total erosion of the hard crust due to continuous wave action for: ； Before calculating the water pressure growth factor, perform the following steps: Determine the hydrodynamic parameters of the hard crust under extreme sea conditions. The hydrodynamic parameters include , , , and , the original soil samples were taken from the hard crust layer using a drill and transported back to the laboratory for testing using the pycnometer method. The original soil samples were dried and crushed, and the sieving method and moisture method were used to test the .

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