Prediction method for one-dimensional consolidation compression curve of high-water-content sludge-sand mixture

Abstract

The invention discloses a method for predicting a one-dimensional consolidation compression curve of a high-water-content sludge-sand mixture. The method comprises the following steps: selecting high-water-content sludge and standard sand to prepare the sludge-sand mixture; carrying out indoor test on the prepared sludge-sand mixture; performing a one-dimensional consolidation compression test on the sludge-sand mixture; determining a mathematical expression of a one-dimensional consolidation compression curve of the sludge-sand mixture; fitting compression model parameters required in the mathematical expression through a least square method; performing fitting analysis on the compression model parameters and soil property parameters to obtain an empirical relationship between the compression model parameters and an initial void ratio and a liquid limit void ratio; the initial void ratio and the liquid limit void ratio of the sludge-sand mixture are measured through a soil test, and the one-dimensional consolidation compression curve of the high-water-content sludge-sand mixture is predicted according to the empirical relation and the mathematical expression. According to the method, the compression curve of the high-water-content sludge-sand mixture starting from the extremely low stress level is rapidly estimated.

Description

Technical Field

[0001] The invention relates to the field of soft soil mechanical parameter determination, in particular to a method for predicting a one-dimensional consolidation compression curve of a high-water content silt-sand mixture. Background Art

[0002] In recent years, with the development of economy, my country has carried out large-scale dredging and desilting projects for coastal rivers, water conservancy hubs, waterways and ports every year, which has produced a large amount of mud and sand. According to incomplete statistics: the amount of mud and sand produced by dredging projects in my country has reached hundreds of millions of cubic meters each year. Since 2010, the total amount of dredging projects in my country has increased from 1.76 billion m3 per year to 2.5 billion m3 per year. 3 Increased year by year to more than 5 billion m 3 During dredging, dredgers and high-pressure mud pumps are used to deposit the mud and sand in the original place in the yard through hydraulic filling, forming a dredging yard where silt and sand coexist. The project will inevitably face the problem of handling a large amount of silt-sand mixture waste.

[0003] Accurately predicting deformation plays a vital role in the design of soft foundation treatment of silt-sand mixture yards. The deformation of silt-sand mixtures is directly related to the compression characteristics of silt-sand mixtures. Traditionally, one-dimensional consolidation tests are used to determine the compression curve of silt-sand mixtures. It takes at least 36 days to conduct a set of one-dimensional consolidation compression experiments starting from 0.5kPa to 1600kPa. When loaded at extremely low stress levels, the cap and permeable stone are very easy to tilt, and staff with rich test operation experience are required to ensure the quality of the test. This has brought great inconvenience to the accurate prediction of the compression characteristics of silt-sand mixtures in the design of silt-sand mixture treatment. At present, there is an urgent need to propose a method that can quickly predict the relationship between the porosity ratio and effective stress of silt-sand mixtures.

[0004] Previous studies have shown that when the initial moisture content of the silt-sand mixture (w 0 ) at the liquid limit (w L ) is within the range of 1.0 to 1.5 times, the e-logσ of the silt-sand mixture v The compression curve starts from a low stress level of 0.5 kPa and roughly takes an inverse "S" shape within a certain stress range. v '≥10kPa, e-logσ v The shape of the compression curve is slightly concave. During the compression process, the compression characteristics of the silt-sand mixture increase with σ v 'Changes with the changes.

[0005] Traditionally, the piecewise linear semi-logarithmic model e-logσ is usually used v 'Or double logarithmic model log(1+e)-logσ v'Simulate the compression curve of silt-sand mixture. However, a large amount of experimental data shows that the double logarithmic model cannot accurately simulate the nonlinear characteristics of the compression curve of silt-sand mixture. At the same time, the more stress segments, the more parameters the compression model requires. The piecewise linear compression model is discontinuous within the stress range, and there are singular points between stress segments. The singularity leads to the de / d(logσ v The non-differentiability of ') between two adjacent stress segments limits the use of piecewise linear compression models in consolidation analysis.

[0006] To solve the above problems, the present invention discloses a mathematical model that can simulate the compression curve of silt-sand mixture from low stress level to 1600kPa, and establishes an empirical relationship between three model parameters and physical indicators of silt-sand mixture (initial porosity and liquid limit porosity). Summary of the invention

[0007] In view of this, the purpose of the present invention is to propose a prediction method for the one-dimensional consolidation compression curve of a high-water content silt-sand mixture, which can quickly and accurately estimate the compression curve of the remolded soil starting from an extremely low stress level on the basis of basic geotechnical tests, thereby solving the problem of measuring the compression curve of the remolded soil over dozens of days.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0009] The present invention provides a method for predicting a one-dimensional consolidation compression curve of a high-water content silt-sand mixture, comprising the following steps:

[0010] Step 1, selecting high-water content silt and standard sand to prepare a silt-sand mixture;

[0011] Step 2, conducting indoor tests on the prepared silt-sand mixture to determine soil parameters through indoor tests;

[0012] Step 3, performing a one-dimensional consolidation compression test on the silt-sand mixture with determined soil parameters;

[0013] Step 4, according to the inverted S-shape characteristics of the one-dimensional consolidation compression curve of the silt-sand mixture with different soil parameters, determine the mathematical expression of the one-dimensional consolidation compression curve of the silt-sand mixture;

[0014] Step 5: Fit the compression model parameters required in the mathematical expression by the least square method;

[0015] Step 6: fitting and analyzing the compression model parameters and soil property parameters to obtain an empirical relationship between the compression model parameters and the initial porosity and liquid limit porosity;

[0016] Step 7: using geotechnical tests to determine the initial porosity and liquid limit porosity of the silt-sand mixture, and predicting the one-dimensional consolidation compression curve of the high-water-content silt-sand mixture based on the empirical relationship and mathematical expression.

[0017] Furthermore, the soil property parameters in step 2 include: initial moisture content w 0 , liquid limit water content w L , soil specific gravity d s and the specific gravity of the silt-sand mixture d s ', among which, the soil parameters determined by indoor tests specifically include:

[0018] Step 21: Determine the initial moisture content w of the sludge-sand mixture by drying method 0 ;

[0019] Step 22: Determine the specific gravity of the soil by pycnometer method s and the specific gravity of the silt-sand mixture d s ';

[0020] Step 23: Determine the liquid limit moisture content w of the silt-sand mixture by using a liquid-plastic limit combined measuring instrument. L .

[0021] Furthermore, the step 21 specifically includes:

[0022] Step 211, select a sludge-sand mixture and put it into a weighing box to weigh the weight of the weighing box and the sludge-sand mixture;

[0023] Step 212, placing the weighing box containing the silt-sand mixture into an oven, and drying it at a constant temperature of 105° C. to 110° C. for a drying time of not less than 8 hours;

[0024] Step 213, taking out the dried sludge-sand mixture, cooling it, and then weighing the mass;

[0025] Step 214: Determine the initial moisture content w of the sludge-sand mixture based on the mass before and after drying. 0 .

[0026] Furthermore, the step 22 specifically includes:

[0027] Step 221, putting the dried sludge-sand mixture into a specific gravity bottle, and weighing the specific gravity bottle and the sludge-sand mixture;

[0028] Step 222, after injecting pure water to half of the bottle, boil it for 55 to 65 minutes to remove gas in the sludge-sand mixture, and cool it;

[0029] Step 223, after cooling, fill the pycnometer with pure water, weigh the total mass and measure the water temperature in the pycnometer;

[0030] Step 224: Determine the specific gravity of the soil based on the density of the silt-sand mixture and the density of pure water. s ;

[0031] Step 225: The specific gravity of the soil s The specific gravity of the silt-sand mixture is calculated by weighted average method according to the sand-soil ratio. s '.

[0032] Furthermore, the step 23 specifically includes:

[0033] Step 231, take 190-210g of the prepared silt-sand mixture, divide it into three parts, add different amounts of water, adjust it into a uniform paste, let it stand for at least 24 hours, fill it into the sample cup densely, and use a soil knife to scrape the silt-sand mixture to make it level with the remaining soil above the sample cup;

[0034] Step 232, place one of the sample cups on the base of the instrument, adjust the height so that the tip of the cone contacts the plane of the silt-sand mixture, press the measurement key, and the cone falls freely. After 4-6 seconds, measure the sinking depth of the cone, then take out the sample cup, take a sample near the cone of not less than 10g, weigh it, and measure the moisture content; repeat step 232 to test the cone sinking depth and moisture content of the remaining two samples;

[0035] Step 233: Draw a curve of the relationship between water content and sinking depth on a double logarithmic coordinate paper, and determine the water content corresponding to the sinking depth of 17 mm as the liquid limit water content w L .

[0036] Furthermore, the step 3 specifically includes:

[0037] Step 31, using a low stress initial consolidation instrument, wherein the cap above the silt-sand mixture in the low stress initial consolidation instrument is an organic material cap, and the weight of the organic material cap is set to 0.5 kPa, so that the minimum load loaded on the low stress initial consolidation instrument is 0.5 kPa;

[0038] Step 32: Control the load of the low stress initial consolidation instrument by adjusting the weight of the weight, wherein the low stress initial consolidation instrument includes 12 loading stages, namely 0.5 kPa, 1.5 kPa, 3.125 kPa, 6.25 kPa, 12.5 kPa, 25 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, 800 kPa and 1600 kPa, wherein each load level is consolidated for 3 days and the total consolidation time is 36 days; complete the consolidation compression test.

[0039] Furthermore, the step 4 is specifically as follows:

[0040] Based on the data of silt-sand mixtures obtained from the existing experiments, the different initial water contents w 0 and different liquid limit water content w L The one-dimensional consolidation compression curve of the silt-sand mixture has an inverted S-shaped feature.

[0041] The following mathematical expression is proposed to simulate the e-σ of silt-sand mixtures: v 'One-dimensional consolidation compression curve:

[0042]

[0043] Among them, A 1 , A 2 , A 3 , A 4 and A 5 is the compression model parameter, e represents the porosity ratio at the current stage, σ v ' represents the effective vertical stress.

[0044] Furthermore, the step 5 specifically includes:

[0045] Step 51: According to the boundary conditions of the one-dimensional consolidation compression curve of the silt-sand mixture, when the vertical stress is 0, the porosity ratio e in the current stage is equal to the initial porosity ratio e 0 ,Right now:

[0046] When σ v When '=0kPa, e=e 0 ,at this time:

[0047] A 1 =e 0 (2)

[0048] Among them, e 0 is the initial void ratio;

[0049] When σ v 'When it approaches infinity, the value of e approaches 0, at this time:

[0050] A 2 =0 (3)

[0051] Step 52: Combining formulas (1) to (3), determine the expression of the void ratio e as follows:

[0052]

[0053] Furthermore, the step 6 is specifically as follows:

[0054] The soil parameters obtained from the indoor test in step 2 and multiple sets of remolded clay parameters obtained from existing experiments are used as soil data sets to establish the compression model parameters A3 , A 4 and A 5 The initial porosity ratio e 0 and liquid limit porosity ratio e L The empirical relationship between them is established as follows:

[0055] A 3 =29.137e 0 +18.037e L -31.146(e 0 ) 2 +11.548(e L ) 2 +4.5175(e 0 ) 3 -2.373(e L ) 3 (5)

[0056] A 4 =1.462e 0 - 0.631e L - 0.132(e 0 ) 2 +0.139(e L ) 2 - 0.024(e 0 ) 3 + 0.008(e L ) 3 (6)

[0057] A 5 = 0.567e 0 - 0.321e L - 0.214(e 0 ) 2 + 0.114(e L ) 2 +0.023(e 0 ) 3 -0.013(e L ) 3 (7).

[0058] Furthermore, the step 7 specifically includes:

[0059] Step 71: Measure the initial moisture content w of the target sludge-sand mixture through indoor tests. 0 , liquid limit water content w L and the specific gravity of the silt-sand mixture d s 'Calculate the initial porosity ratio e 0 and liquid limit porosity ratio e L ; The formula is as follows:

[0060] e 0 =d s '×w 0 ;

[0061] e L =d s '×w L ;

[0062] Step 72: The calculated initial void ratio e 0 and liquid limit porosity ratio e L Substitute into formulas (5), (6) and (7) to obtain the compression model parameter A 3 , A 4 and A 5 ;

[0063] Step 73: The obtained compression model parameter A 3 , A 4 and A 5 Substituting into formula (4), we get the one-dimensional consolidation compression curve of the target silt-sand mixture.

[0064] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0065] 1. The invention is clear and logical, and the proposed mathematical expression can simulate the complete compression curve of the high-water content silt-sand mixture in the range from the initial porosity to the 1600 kPa stress level, with high fitting accuracy;

[0066] 2. The mathematical expression proposed by the present invention is smooth and continuous, has few compression model parameters, and can accurately simulate the nonlinear continuous change characteristics of the slope of the one-dimensional consolidation compression curve of the silt-sand mixture;

[0067] 3. The present invention can be used to carry out basic geotechnical tests and determine the initial soil moisture content w 0 , liquid limit water content w L and the specific gravity of the silt-sand mixture d s ', the compression curve of the remolded soil starting from an extremely low stress level can be quickly and accurately estimated, which solves the problem of measuring the compression curve of the remolded soil over dozens of days and effectively shortens the test time. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0069] Figure 1 The present invention is a flow chart of a method for predicting a one-dimensional consolidation compression curve of a high-water content silt-sand mixture.

[0070] Figure 2 Graph showing a typical compression curve of the silt-sand mixture of Table 1 of the present invention.

[0071] Figure 3 It is a comparison chart of the porosity of the silt-sand mixture in Table 1 of the present invention calculated by the proposed model and the measured value.

[0072] Figure 4 The accuracy of the empirical method proposed in Table 1 of the present invention for silt-sand mixtures.

[0073] Figure 5 A typical compression curve of a silt-sand mixture of an engineering example of the present invention. DETAILED DESCRIPTION

[0074] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0075] See also Figure 1-Figure 5 A method for predicting a one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to the present invention comprises the following steps:

[0076] Step 1: Select high-water content sludge and standard sand to prepare a sludge-sand mixture; under normal working conditions, the water content of the blown fill sludge-sand mixture is 1w L The applicable range of the high moisture content in the prediction method proposed in this paper is higher than 1.6w L .

[0077] In this embodiment, the step 1 specifically includes: selecting high-water content silt and standard sand according to the test requirements, stirring them evenly, and preparing a silt-sand mixture, which can provide a homogeneous silt-sand mixture for testing.

[0078] Step 2: Conduct an indoor test on the prepared silt-sand mixture to determine soil parameters through the indoor test. The soil parameters include: initial water content w 0 , liquid limit water content w L , soil specific gravity d s and the specific gravity of the silt-sand mixture d s ';

[0079] In this embodiment, step 2 specifically includes:

[0080] Step 21: Determine the initial moisture content w of the sludge-sand mixture by drying method 0 ; Specifically include:

[0081] Step 211, select a sludge-sand mixture and put it into a weighing box to weigh the weight of the weighing box and the sludge-sand mixture;

[0082] Step 212, placing the weighing box containing the silt-sand mixture into an oven, and drying it at a constant temperature of 105° C. to 110° C. for a drying time of not less than 8 hours;

[0083] Step 213, taking out the dried sludge-sand mixture, cooling it, and then weighing the mass;

[0084] Step 214: Determine the initial moisture content w of the sludge-sand mixture based on the mass before and after drying. 0 .

[0085] Step 22: Determine the specific gravity of the soil by pycnometer method s and the specific gravity of the silt-sand mixture d s '; Specifically include:

[0086] Step 221, putting the dried sludge-sand mixture into a specific gravity bottle, and weighing the specific gravity bottle and the sludge-sand mixture;

[0087] Step 222, after injecting pure water to half of the bottle, boil it for 55 to 65 minutes to remove gas in the sludge-sand mixture, and cool it;

[0088] Step 223, after cooling, fill the pycnometer with pure water, weigh the total mass and measure the water temperature in the pycnometer;

[0089] Step 224: Determine the specific gravity of the soil based on the density of the silt-sand mixture and the density of pure water (generally 4° C. pure water). s ;

[0090] Step 225: The specific gravity of the soil s The specific gravity of the silt-sand mixture is calculated by weighted average method according to the sand-soil ratio. s '.

[0091] Step 23: Determine the liquid limit moisture content w of the silt-sand mixture by using a liquid-plastic limit combined measuring instrument. L ; Specifically include:

[0092] Step 231, take 190-210g (usually 200g) of the prepared silt-sand mixture, divide it into three parts, add different amounts of water, adjust it into a uniform paste, let it stand for at least 24 hours (usually 24 hours), fill it into the sample cup densely, and use a soil knife to scrape the excess soil above the sample cup to make the silt-sand mixture level;

[0093] Step 232, place one of the sample cups on the base of the instrument, adjust the height so that the tip of the cone contacts the plane of the silt-sand mixture, press the measurement key, and the cone falls freely. After 4-6 seconds (usually 5 seconds), the sinking depth of the cone is measured, and then the sample cup is taken out, and a sample of not less than 10g near the cone is taken, weighed, and the moisture content is determined; repeat step 232 to test the cone sinking depth and moisture content of the remaining two samples;

[0094] Step 233: Draw a curve of the relationship between water content and sinking depth on a double logarithmic coordinate paper, and determine the water content corresponding to the sinking depth of 17 mm as the liquid limit water content w L .

[0095] Step 3, performing a one-dimensional consolidation compression test on the silt-sand mixture with determined soil parameters;

[0096] In this embodiment, step 3 specifically includes:

[0097] Step 31, using a low stress initial consolidation instrument, which is a new structure different from the traditional consolidation instrument; the cap above the silt-sand mixture in the low stress initial consolidation instrument is an organic material cap, and the weight of the organic material cap is set to 0.5 kPa, so that the minimum load loaded by the low stress initial consolidation instrument is 0.5 kPa; the organic material cap is used to replace the traditional metal cap. Since the organic material cap is lighter than the metal cap, the load applied when only the cap is placed is 0.5 kPa, so that the consolidation starting load is reduced from 6.25 kPa of the traditional consolidation instrument to 0.5 kPa;

[0098] Step 32, by adjusting the weight of the weight to control the load of the low stress initial consolidation instrument, after placing the organic material cap on the top of the silt-sand mixture, a set of weights are hung directly below the low stress initial consolidation instrument, and two levels of loads of 1.5kPa and 3.125kPa are added during the consolidation process; since the starting load of the traditional consolidation instrument is 6.25kPa, half of 6.25kPa and about a quarter of the load are added. The load after 6.25kPa is similar to that of the traditional consolidation instrument, and the corresponding load is applied by hanging weights at the front of the low stress initial consolidation instrument;

[0099] Step 33, the low stress initial consolidation instrument includes 12 loading stages, namely 0.5kPa, 1.5kPa, 3.125kPa, 6.25kPa, 12.5kPa, 25kPa, 50kPa, 100kPa, 200kPa, 400kPa, 800kPa and 1600kPa, each level of load consolidation is 3 days, and the total consolidation time is 36 days; complete the consolidation compression test. By changing the material of the cap from metal to organic material and adding appropriate weights under the low stress initial oedometer, three new characteristics of 0.5kPa, 1.5kPa and 3.125kPa can be added to the traditional oedometer; the loading stage of the low stress initial oedometer is changed from 9 characteristics of 6.25kPa, 12.5kPa, 25kPa, 50kPa, 100kPa, 200kPa, 400kPa, 800kPa and 1600kPa to 12 characteristics of 0.5kPa, 1.5kPa, 3.125kPa, 6.25kPa, 12.5kPa, 25kPa, 50kPa, 100kPa, 200kPa, 400kPa, 800kPa and 1600kPa. After adding three loading stages with lower stress levels, the test range is greatly improved, making the test results more precise and the regression equation more accurate.

[0100] Step 4, according to the inverted S-shape characteristics of the one-dimensional consolidation compression curve of the silt-sand mixture with different soil parameters, determine the mathematical expression of the one-dimensional consolidation compression curve of the silt-sand mixture;

[0101] In this embodiment, step 4 is specifically as follows:

[0102] Based on the data of silt-sand mixtures obtained from the existing experiments, the different initial water contents w 0 and different liquid limit water content w L One-dimensional consolidation compression curve of silt-sand mixture; The one-dimensional consolidation compression curve of silt-sand mixture has an inverted S-shaped feature. When the stress level is small, the porosity changes little; when the stress level exceeds the yield stress, the soil structure collapses and the porosity decreases rapidly.

[0103] The following mathematical expression is proposed to simulate the e-σ of silt-sand mixtures: v 'One-dimensional consolidation compression curve:

[0104]

[0105] Among them, A 1 , A 2 , A 3 , A 4 and A 5is the compression model parameter, e represents the porosity ratio at the current stage, σ v ' represents the effective vertical stress.

[0106] Step 5: Fit the compression model parameters required in the mathematical expression by the least square method;

[0107] In this embodiment, step 5 specifically includes:

[0108] Step 51: According to the boundary conditions of the one-dimensional consolidation compression curve of the silt-sand mixture, when the vertical stress is 0, the porosity ratio e in the current stage is equal to the initial porosity ratio e 0 ,Right now:

[0109] When σ v When '=0kPa, e=e 0 ,at this time:

[0110] A 1 =e 0 (2)

[0111] Among them, e 0 is the initial void ratio;

[0112] When σ v 'When it approaches infinity, the value of e approaches 0, at this time:

[0113] A 2 =0 (3)

[0114] Step 52: Combining formulas (1) to (3), determine the expression of the void ratio e as follows:

[0115]

[0116] By using the characteristics of formulas (2) and (3), formula (1) can be converted into formula (4), which is more convenient for the use of mathematical expressions.

[0117] Step 6: fitting and analyzing the compression model parameters and soil property parameters to obtain an empirical relationship between the compression model parameters and the initial porosity and liquid limit porosity;

[0118] In this embodiment, step 6 is specifically as follows:

[0119] The soil parameters obtained from the indoor test in step 2 and multiple sets of remolded clay parameters obtained from existing experiments are used as soil data sets to establish the compression model parameters A 3 , A 4 and A 5 The initial porosity ratio e 0 and liquid limit porosity ratio e L The empirical relationship between them is established as follows:

[0120] A 3 =29.137e 0 +18.037e L -31.146(e 0 ) 2 +11.548(e L ) 2 +4.5175(e 0 ) 3 -2.373(e L ) 3 (5)

[0121] A 4 =1.462e 0 -0.631e L -0.132(e 0 ) 2 +0.139(e L ) 2 -0.024(e 0 ) 3 +0.008(e L ) 3 (6)

[0122] A 5 =0.567e 0 -0.321e L -0.214(e 0 ) 2 +0.114(e L ) 2 +0.023(e 0 ) 3 -0.013(e L ) 3 (7).

[0123] Step 7: using geotechnical tests to determine the initial porosity and liquid limit porosity of the silt-sand mixture, and predicting the one-dimensional consolidation compression curve of the high-water-content silt-sand mixture based on the empirical relationship and mathematical expression without determining the compression curve through a consolidation test.

[0124] In this embodiment, step 7 specifically includes:

[0125] Step 71: Measure the initial moisture content w of the target sludge-sand mixture through indoor tests. 0 , liquid limit water content w L and the specific gravity of the silt-sand mixture d s 'Calculate the initial porosity ratio e 0 and liquid limit porosity ratio e L ; The formula is as follows:

[0126] e 0 =d s '×w 0 ;

[0127] e L =d s '×w L ;

[0128] Step 72: The calculated initial void ratio e 0 and liquid limit porosity ratio e L Substitute into formulas (5), (6) and (7) to obtain the compression model parameter A 3 , A 4 and A 5 ;

[0129] Step 73: The obtained compression model parameter A 3 , A 4 and A 5 Substituting into formula (4), we get the one-dimensional consolidation compression curve of the target silt-sand mixture.

[0130] Example

[0131] In a certain project, according to the survey data (as shown in Table 1), the method of the present invention is used to determine a simple, smooth and continuous silt compression curve from a low stress level (0.5 kPa) to 1600 kPa during the construction process. The soil conditions are as follows: Soil specific gravity G s =2.72Mg / m 3 , liquid limit water content w L =60.0%, initial water content w 0 =50%. After calculation, we can get: initial porosity ratio e 0 =1.36, liquid limit porosity ratio e L =1.632. Substituting into equations (5), (6), and (7), we obtain: A 3 =43.260, A 4 =1.059, A 5 =0.158. The values ​​obtained by the above calculation are plotted into a curve as shown in the attached figure. Figure 5 shown.

[0132] Table 1 Measured compression consolidation test data

[0133]

[0134] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture, characterized in that: The steps include: Step 1, selecting high-water content silt and standard sand to prepare a silt-sand mixture; Step 2, conducting indoor tests on the prepared silt-sand mixture to determine soil parameters through indoor tests; Step 3, performing a one-dimensional consolidation compression test on the silt-sand mixture with determined soil parameters; Step 4, according to the inverted S-shape characteristics of the one-dimensional consolidation compression curve of the silt-sand mixture with different soil parameters, determine the mathematical expression of the one-dimensional consolidation compression curve of the silt-sand mixture; Step 5: Fit the compression model parameters required in the mathematical expression by the least square method; Step 6: fitting and analyzing the compression model parameters and soil property parameters to obtain an empirical relationship between the compression model parameters and the initial porosity and liquid limit porosity; Step 7: using geotechnical tests to determine the initial porosity and liquid limit porosity of the silt-sand mixture, and predicting the one-dimensional consolidation compression curve of the high-water-content silt-sand mixture based on the empirical relationship and mathematical expression.

2. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 1, characterized in that: The soil property parameters in step 2 include: initial moisture content w0, liquid limit moisture content w L , soil specific gravity d s and the specific gravity of the silt-sand mixture d s ', among which, the soil parameters determined by indoor tests specifically include: Step 21, determining the initial moisture content w0 of the sludge-sand mixture by a drying method; Step 22: Determine the specific gravity of the soil by pycnometer method s and the specific gravity of the silt-sand mixture d s '; Step 23: Determine the liquid limit moisture content w of the silt-sand mixture by using a liquid-plastic limit combined measuring instrument. L .

3. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 2, characterized in that: The step 21 specifically includes: Step 211, select a sludge-sand mixture and put it into a weighing box to weigh the weight of the weighing box and the sludge-sand mixture; Step 212, placing the weighing box containing the silt-sand mixture into an oven, and drying it at a constant temperature of 105° C. to 110° C. for a drying time of not less than 8 hours; Step 213, taking out the dried sludge-sand mixture, cooling it, and then weighing the mass; Step 214: determine the initial moisture content w0 of the sludge-sand mixture based on the mass before and after drying.

4. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 3, characterized in that: The step 22 specifically includes: Step 221, putting the dried sludge-sand mixture into a specific gravity bottle, and weighing the specific gravity bottle and the sludge-sand mixture; Step 222, after injecting pure water to half of the bottle, boil it for 55 to 65 minutes to remove gas in the sludge-sand mixture, and cool it; Step 223, after cooling, fill the pycnometer with pure water, weigh the total mass and measure the water temperature in the pycnometer; Step 224: Determine the specific gravity of the soil based on the density of the silt-sand mixture and the density of pure water. s ; Step 225: The specific gravity of the soil s The specific gravity of the silt-sand mixture is calculated by weighted average method according to the sand-soil ratio. s '.

5. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 4, characterized in that: The step 23 specifically includes: Step 231, take 190-210g of the prepared silt-sand mixture, divide it into three parts, add different amounts of water, adjust it into a uniform paste, let it stand for at least 24 hours, fill it into the sample cup densely, and use a soil knife to scrape the silt-sand mixture to make it level with the remaining soil above the sample cup; Step 232, place one of the sample cups on the base of the instrument, adjust the height so that the tip of the cone contacts the plane of the silt-sand mixture, press the measurement key, and the cone falls freely. After 4-6 seconds, measure the sinking depth of the cone, then take out the sample cup, take a sample near the cone of not less than 10g, weigh it, and measure the moisture content; repeat step 232 to test the cone sinking depth and moisture content of the remaining two samples; Step 233: Draw a curve of the relationship between water content and sinking depth on a double logarithmic coordinate paper, and determine the water content corresponding to the sinking depth of 17 mm as the liquid limit water content w L .

6. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 1, characterized in that: The step 3 specifically includes: Step 31, using a low stress initial consolidation instrument, wherein the cap above the silt-sand mixture in the low stress initial consolidation instrument is an organic material cap, and the weight of the organic material cap is set to 0.5 kPa, so that the minimum load loaded on the low stress initial consolidation instrument is 0.5 kPa; Step 32: Control the load of the low stress initial consolidation instrument by adjusting the weight of the weight, wherein the low stress initial consolidation instrument includes 12 loading stages, namely 0.5 kPa, 1.5 kPa, 3.125 kPa, 6.25 kPa, 12.5 kPa, 25 kPa, 50 kPa, 100 kPa, 200 kPa, 400 kPa, 800 kPa and 1600 kPa, wherein each load level is consolidated for 3 days and the total consolidation time is 36 days; complete the consolidation compression test.

7. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 1, characterized in that: The step 4 is specifically as follows: Based on the existing experimental data of silt-sand mixtures, different initial water contents w0 and different liquid limit water contents w L The one-dimensional consolidation compression curve of the silt-sand mixture has an inverted S-shaped feature. The following mathematical expression is proposed to simulate the e-σ of silt-sand mixtures: v 'One-dimensional consolidation compression curve: Among them, A1, A2, A3, A4 and A5 are compression model parameters, e represents the porosity ratio at the current stage, σ v ' represents the effective vertical stress.

8. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 7, characterized in that: The step 5 specifically includes: Step 51: According to the boundary conditions of the one-dimensional consolidation compression curve of the silt-sand mixture, when the vertical stress is 0, the porosity e in the current stage is the initial porosity e0, that is: When σ v When '=0kPa, e=e0, then: A1=e0 (2) Where, e0 is the initial porosity ratio; When σ v 'When it approaches infinity, the value of e approaches 0, at this time: A2＝0 (3) Step 52: Combining formulas (1) to (3), determine the expression of the void ratio e as follows:

9. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 8, characterized in that: The step 6 is specifically as follows: The soil parameters obtained from the indoor test in step 2 and multiple sets of remolded clay parameters obtained from existing experiments are used as soil data sets to establish the compression model parameters A3, A4 and A5 and the initial porosity e0 and liquid limit porosity e L The empirical relationship between them is established as follows: <h2 style=";text-align:left;direction:ltr">A3 = 29.137e0 + 18.037e<h2 style=";text-align:left;direction:ltr"> L <h2 style=";text-align:left;direction:ltr"> -31.146(e0)<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +11.548(e<h2 style=";text-align:left;direction:ltr"> L <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +4.5175(e0)<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> -2.373(e<h2 style=";text-align:left;direction:ltr"> L <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> (5) A4=1.462e0 - 0.631e L − 0.132(e0) 2 +0.139(e L ) 2 − 0.024(e0) 3 + 0.008(e L ) 3 (6) <h2 style=";text-align:left;direction:ltr">A5 = 0.567e0 - 0.321e<h2 style=";text-align:left;direction:ltr"> L <h2 style=";text-align:left;direction:ltr"> - 0.214(e0)<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> + 0.114(e<h2 style=";text-align:left;direction:ltr"> L <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +0.023(e0)<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> -0.013(e<h2 style=";text-align:left;direction:ltr"> L <h2 style=";text-align:left;direction:ltr"> )<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> (7) 10. The method for predicting the one-dimensional consolidation compression curve of a high-water content silt-sand mixture according to claim 9, characterized in that: The step 7 specifically includes: Step 71: Measure the initial moisture content w0 and liquid limit moisture content w0 of the target sludge-sand mixture through indoor tests. L and the specific gravity of the silt-sand mixture d s 'Calculate the initial porosity e0 and liquid limit porosity e L ; The formula is as follows: e0=d s '×w0; e L =d s ’×w L ; Step 72: The calculated initial porosity ratio e0 and liquid limit porosity ratio e L Substitute into formulas (5), (6) and (7) to obtain the compression model parameters A3, A4 and A5; Step 73: Substitute the obtained compression model parameters A3, A4 and A5 into formula (4), which is the one-dimensional consolidation compression curve of the target silt-sand mixture.

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