A method for determining the suitable mixing proportion of high clay content foam light soil for reconstruction and expansion embankment of soft soil road section

Abstract

The present application relates to the technical field of road reconstruction engineering, and especially relates to a method for determining the suitable mixing proportion of high-clay content foam light soil of embankment of soft soil section reconstruction, which comprises the following steps: step 1, determination of the improved critical density (ρ cr ) of foam light soil; step 2, determination of the sequence of the influence of the mixing amount factor on the strength and density of foam light soil; step 3, determination of the suitable mixing proportion of foam light soil; and step 4, according to the determined suitable mixing proportion of foam light soil, soil engineering tests on the density and unconfined compressive strength of large-size foam light soil cubic test blocks are carried out to verify the feasibility of foam light soil in actual engineering. The present application can ensure that foam light soil can meet the requirements of relevant roadbed specifications while realizing the effects of cost saving and environmental protection in roadbed construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road reconstruction and extension engineering, and particularly relates to a method for determining the suitable mixing proportion of high clay content foam light soil for embankment of soft soil road section reconstruction and extension. BACKGROUND

[0002] The road reconstruction and extension engineering is a kind of engineering project of newly building and widening the road on the basis of the original road foundation. Since the original road foundation has basically completed the settlement consolidation, the newly built and widened road foundation will have a large construction period consolidation settlement after the embankment load is applied, especially in the soft soil section. Due to the large compression coefficient and significant rheological property of the soft soil, the soft soil foundation will have a large consolidation settlement under the self-weight of the newly built embankment during the construction period. When the construction speed is too fast, in addition to causing excessive differential settlement damage, the embankment is also prone to serious sliding deformation damage.

[0003] In order to solve the problems of differential settlement and sliding damage of the new and old embankments in the soft soil section of the road reconstruction and extension engineering, the present application develops a new type of cast-in-place solidified embankment filler, i.e. foam light soil, by using part of the embankment fill to replace the cement in the foam concrete according to the construction method of the foam concrete. The foam light soil has the characteristics of light weight, adjustable strength and density, good upright property, fast molding, and convenient construction. However, the problem of making the foam light soil is that: after part of the embankment fill is used to replace the cement, not only the consistency of the foam light soil slurry increases, the foaming efficiency decreases, and the density of the foam light soil increases, but also the strength of the foam light soil decreases due to the addition of the soil material. Therefore, the difficulty of making the foam light soil is that: when the fill content is small, it is difficult to overcome the defects of high cost and poor environmental protection of the foam concrete roadbed; but when the fill content is large, it is difficult to ensure that the foam light soil has high enough strength and low enough density to meet the requirements of the roadbed specification. At present, the mixing proportion of the foam light soil filler cannot be determined by theoretical calculation, and the strength of the foam light soil formed after the addition of the fill material will decrease by a large margin, and the density will increase by a large margin, which limits the application range of the foam light soil in the widened embankment in the soft soil foundation section to a certain extent. Therefore, the suitable mixing proportion of the foam light soil is closely related to the strength and compressibility of the soft soil foundation, and is also greatly affected by the engineering properties of the embankment filler soil and the embankment filling height. Therefore, how to determine the suitable mixing amount of various materials in the foam light soil construction process has become a problem in making the foam light soil. SUMMARY

[0004] The main problem to be solved by the present application is how to determine the suitable mixing proportion of foam lightweight soil filling suitable for soft soil foundation section widening embankment, so as to ensure that the foam lightweight soil can meet the relevant roadbed specification requirements in roadbed construction, and at the same time, the purposes of cost saving and environmental protection can be achieved, and the present application provides a method for determining the suitable mixing proportion of high clay content foam lightweight soil of soft soil section reconstruction embankment, wherein, the rock and soil parameters of each soil layer of the soft soil foundation are obtained according to the rock and soil engineering investigation data of the soft soil section site, the initial values of each mixed material are calculated, then the orthogonal test method is adopted to analyze the importance of different mixing amount factors on the density index and strength index of the foam lightweight soil, and finally, the suitable mixing proportion of the foam lightweight soil is obtained by using the density and strength double index slope intersection analysis method according to the experimental results of the mixing proportion.

[0005] The above application object of the present application is realized by the following technical scheme:

[0006] A method for determining the suitable mixing proportion of high clay content foam lightweight soil of soft soil section reconstruction embankment, comprising the following steps:

[0007] Step 1: determination of the improved critical density (ρ cr ) of the foam lightweight soil: the rock and soil parameters of each soil layer of the soft soil foundation are obtained according to the rock and soil engineering investigation data of the soft soil section site, and the load (f0) on the ground surface is set as the design value (f) of the bearing capacity of the soft soil foundation, the initial calculation critical density (ρ'3) of the foam lightweight soil is calculated, the first calculation ground settlement (S1) is calculated according to the initial calculation critical density (ρ'3) of the foam lightweight soil and the design height (h) of the embankment, if the first calculation ground settlement (S1) is greater than the design ground settlement (S0), the initial calculation critical density (ρ'3) of the foam lightweight soil is taken as the critical density (ρ cr ) and is reduced to obtain the second calculation critical density (ρ'3'), then the second calculation ground settlement (S2) is calculated according to the second calculation critical density (ρ'3') and the design height (h) of the embankment, if the second calculation ground settlement (S2) is greater than the design ground settlement (S0), the above steps are repeated to calculate the i-th calculation ground settlement (S i ) and compare it with the design ground settlement (S0); if the i-th calculation ground settlement (S i ) is less than or equal to the design ground settlement (S0), the calculation critical density (S i ) that first meets the requirement is taken as the critical density (ρ cr ) to determine the improved critical density (ρ cr ) of the foam lightweight soil.

[0008] Step 2: Determination of the order of the influence of the mixing amount factors on the strength and density of the foam lightweight soil: According to the relevant data of modified soil, the median values of the commonly used mixing amount ranges of cement, hydrogen peroxide, water-solids ratio, and stabilizing agent in the modified soil are obtained as the medium mixing amount levels of the four mixing amount factors, namely a 正2 , b 正2 , c 正2 , and d 正2 , respectively. The cement, hydrogen peroxide, water-solids ratio, and stabilizing agent are each taken one low mixing amount level (a 正1 , b 正1 , c 正1 , and d 正1 ) and one high mixing amount level (a 正3 , b 正3 , c 正3 , and d 正3 ) respectively, with a difference.

[0009] Then, the orthogonal test table (Table 1) is prepared according to the data of the low, medium, and high mixing amount levels of the above four mixing amount factors. Table 1 is as follows:

[0010] Table 1 Orthogonal test table of 4 factors and 3 levels

[0011]

[0012] According to Table 1, the density of the foam lightweight soil cubic test block and the unconfined compressive strength of the soil are determined for 9 groups of foam lightweight soil, and the density of 3 foam lightweight soil cubic parallel test blocks of Test Group 1 to Test Group 9 is determined, and the average value is calculated to obtain the density value of each group of orthogonal test: ρ 正1 , ρ 正2 , ρ 正3 … ρ 正9 . The unconfined compressive strength test is performed on the 3 foam lightweight soil cubic parallel test blocks of Test Group 1 to Test Group 9 after the density determination, and the average value is taken as the unconfined compressive strength test value of the group of orthogonal test σ 正1 , σ 正2 , σ 正3 … σ 正9 .

[0013] According to the density determination results, the range analysis is performed on the density (ρ 正 ) of the foam lightweight soil, and the density range values of each mixing amount factor are obtained: the cement density range value R' A , the hydrogen peroxide density range value R' B , the water-solids ratio density range value R' C , and the stabilizing agent density range value R' D . According to the strength test results, the range analysis is performed on the compressive strength (σ 正) and the range value of the compressive strength of each mixing amount factor: the range value of the compressive strength of cement R A , the range value of the compressive strength of hydrogen peroxide R B , the range value of the compressive strength of water-material ratio R C , and the range value of the compressive strength of foam stabilizer R D ;

[0014] According to the range value of the density and the range value of the compressive strength of each mixing amount factor, the weighted coefficient w' j of the influence of each mixing amount factor on the density of the foam lightweight soil and the weighted coefficient w" j of the influence of each mixing amount factor on the compressive strength of the foam lightweight soil are respectively calculated, that is, the density weighted coefficients of cement, hydrogen peroxide, water-material ratio and foam stabilizer are w' A , w' B , w' C , w' D respectively, and the compressive strength weighted coefficients of cement, hydrogen peroxide, water-material ratio and foam stabilizer are w" A , w" B , w" C , w" D ; then, the comprehensive influence coefficient w j of each mixing amount factor on the density (ρ 正 ) and the compressive strength (σ 正 ) of the foam lightweight soil is calculated by using the equal weighted coefficient method, that is, the comprehensive influence coefficients of cement, hydrogen peroxide, water-material ratio and foam stabilizer are w A , w B , w C , w D respectively, and the influence order of the four mixing amount factors of cement, hydrogen peroxide, water-material ratio and foam stabilizer on the compressive strength and the density of the foam lightweight soil is determined according to the comprehensive influence coefficients;

[0015] Step 3: Determination of the suitable mixing proportion of the foam lightweight soil: the relevant data of the improved soil is consulted, and the median value a n / 2 of the usual mixing amount range a1-a n of the cement in the improved soil is obtained as the medium mixing amount level of the cement, which is denoted as x a5 , that is, x a5 =an / 2, and four low cement mixing amount levels x a1 , x a2 , x a3 , x a4 and four high cement mixing amount levels x a6 , x a7 , x a8 , x a9 are respectively taken by using the grade difference, and the medium mixing amount levels x a1 , x a2 , x a3 , x a4 , x a6 , x a7 , x a8 , x a9 of hydrogen peroxide, water-material ratio and foam stabilizer in the foam lightweight soil are obtained.b5 , x c3 and x d4 , and four low levels of dosage x b1 , x b2 , x b3 , x b4 and four high levels of dosage x b6 , x b7 , x b8 , x b9 ; two low levels of water dosage x c1 , x c2 and three high levels of water dosage x c4 , x c5 , x c6 ; four low levels of foam stabilizer dosage x d1 , x d2 , x d3 , x d4 and three high levels of foam stabilizer dosage x d6 , x d7 , x d8 ;

[0016] Step 4: According to the order of the comprehensive influence of the dosage factors from large to small obtained in Step 2: factor (K1), factor (K2), factor (K3), factor (K4), single-factor tests are performed in turn from K1 to K4; the dosage value of factor (K1) is a1-a n , and the dosage values of the remaining three factors are all taken as the median values b n / 2 , c n / 2 , d n / 2 , a soil test for the density and unconfined compressive strength of foam lightweight soil cubic test blocks is designed, the foam lightweight soil test density (p cr ) closest to the critical density (p a ) of the foam lightweight soil is found according to the test results, and whether the unconfined compressive strength s a of the foam lightweight soil at the density meets the requirements is judged according to the requirements of the roadbed specification. If the unconfined compressive strength of the foam lightweight soil meets the requirements, the dosage value at the density is selected as the suitable dosage value (a) of factor (K1); if the unconfined compressive strength does not meet the requirements of the roadbed specification, the dosage value of factor (K1) needs to be appropriately increased;

[0017] Step 5: Factor (K2) is b1-b n , the dosage value of factor (K1) is the suitable dosage value (a), and the dosage values of the remaining two factors are all taken as the median values c n / 2 , d n / 2, a series of geotechnical tests of density and unconfined compressive strength of foam lightweight soil cubic test blocks are designed, and according to the test results, the density values of each group of single-factor tests of the factor (K2) are sequentially recorded as ρ b1 , ρ b2 , ρ b3 … ρ b9 , the unconfined compressive strength test values of each group of tests are sequentially recorded as σ b1 , σ b2 , σ b3 … σ b9 , and the density values and unconfined compressive strength test values are plotted into a point-line graph, and the density slope of each dosage value interval is sequentially calculated according to formula (1) as , and the unconfined compressive strength slope is sequentially Formula (1) is as follows: Wherein, n is the test group number; if the experimental density index ρ bn > ρ cr + 0.2 (g / cm 3 ), the interval is excluded; the density slope and the unconfined compressive strength slope are sorted from large to small, and the intervals with the top three slopes are marked; if the two slope intervals intersect, the dosage value at the midpoint of the interval is taken as the appropriate dosage value (b); if the two slope intervals are tangent, the dosage value at the tangent point is taken as the appropriate dosage value (b); if the two slope intervals are apart, the dosage value at the minimum density of the interval with the maximum slope of the test density (ρ b ) curve is taken as the appropriate dosage value (b), to obtain the appropriate dosage value (b) of the factor (K2);

[0018] Step 6: According to step 5, geotechnical tests of density and unconfined compressive strength of foam lightweight soil cubic test blocks are carried out on the factors (K3) and (K4) in turn, and data analysis is carried out, to obtain the appropriate dosage value (c) of the factor (K3) and the appropriate dosage value (d) of the factor (K4).

[0019] Step 7: According to the appropriate mix proportion of foam lightweight soil determined in steps 5 and 6, geotechnical tests of density and unconfined compressive strength of large-size foam lightweight soil cubic test blocks are carried out, to verify the feasibility of foam lightweight soil in actual engineering.

[0020] Preferably, in step 1, the specific calculation formula (2) of the load (f0) on the ground surface is: f0= (ρ1·h1+ρ2·h2+ρ3·h3)·g+P; the specific calculation formula (3) of the design filling height (h3) of foam lightweight soil is: h3=h-h1-h2; and the specific calculation formula (4) of the initial calculation critical density (ρ'3) of foam lightweight soil is: ρ'3= ((f-P) / g-ρ1·h1-ρ2·h2) / h3;

[0021] In formula (2), formula (3), and formula (4), ρ1 is the density of the material of the road surface structure layer (kg / m 3 ) ; ρ2 is the density of the upper embankment filler (kg / m 3 ) ; ρ3 is the initial value of the critical density of the foam lightweight soil (kg / m 3 ) ; h1 is the height of the road surface structure layer (m) ; h2 is the height of the upper embankment (m) ; h3 is the designed filling height of the foam lightweight soil (m) ; and P is the road surface load of the road.

[0022] Preferably, in step 1, the specific calculation of the i-th checking ground settlement (S i ) is as follows: S c i is the i-th checking ground settlement (m), i = 1, 2, 3, 4; Δσ is the load applied to the embankment (MPa), Δσ = (ρ1·h1+ρ2·h2+ρ'3·h3)·g+P; E is the elastic modulus of the ground soil (MPa) ; h is the height of the embankment (m) ; C i is the compression index of the ground soil; e0 is the initial void ratio of the ground soil; and e is the final void ratio of the ground soil.

[0023] Preferably, in step 1, when the ground settlement (S 3 ) of each checking is greater than the designed ground settlement (S0), the initial calculated critical density of the foam lightweight soil is reduced by 0.2 (g / cm 正1 ).

[0024] Preferably, in step 2, the specific steps of the density determination of the foam lightweight soil cubic test block and the soil test of the unconfined compressive strength are as follows:

[0025] Step (1) : Three foam lightweight soil cubic parallel test blocks with the size of 100 mm × 100 mm × 100 mm are respectively prepared according to the mixing amount level of Table 1 for each test group, the density of the three parallel test blocks of test group 1 is determined, the relative error of the density is calculated, if the relative error of the density of the three parallel test blocks is not greater than ± 2%, the average value of the densities of the three test blocks is taken as the density value of the test group; if the relative error of the density of the three parallel test blocks is greater than ± 2%, the sample preparation is re-performed for the density test until the relative error of the three parallel test blocks is not greater than ± 2%, and then the average value of the densities of the three test blocks is taken as the density value of the orthogonal test group;

[0026] Step (2) : The density determination of the three cubic parallel test blocks of the foam lightweight soil of test group 2 to test group 9 is performed according to step (1), and the average value is calculated to obtain the density values of the orthogonal test groups: ρ 正1 , ρ 正2 , ρ 正3 , …, ρ 正9 .

[0027] Step (3): Conduct unconfined compressive strength tests on the three parallel cubic test blocks after density measurement in each group of orthogonal experiments, and take the average value as the unconfined compressive strength test value of that group of orthogonal experiments, and record it as σ. 正1 σ 正2 σ 正3 …σ 正9 .

[0028] Preferably, in step 2, the weighting coefficient w for the influence of each admixture factor on the density of the foamed lightweight soil is... j The specific calculation formula (6) is as follows: Weighting coefficient w for the influence of various admixture factors on the compressive strength of foamed lightweight soil j The specific calculation formula (7) for “” is as follows: The comprehensive influence coefficient w of various admixture factors on the density and compressive strength of foamed lightweight soil j The specific calculation formula (8) is: w j =0.5*w' j +0.5*w” j ;In formulas (6), (7), (8): w' j R' is the density weighting coefficient; j The density range for each doping factor; w” j R” is the compressive strength weighting factor. j The range of compressive strength for each admixture factor; w j is the comprehensive influence coefficient; j represents the doping factors A, B, C, and D; w' j w” represents the density weighting coefficient for each doping factor j; j is the compressive strength weighting coefficient for each doping factor j.

[0029] Preferably, in step 2, the cement is taken at a low admixture level both downwards and upwards (a) 正1 ) and a high doping level (a 正3 The increments for hydrogen peroxide, water-to-material ratio, and foam stabilizer were 10%, with increments of 0.1%, 0.05%, and 0.2% respectively, resulting in low dosage levels (b) for these components. 正1 c 正1 and d 正1 ) and high doping level (b 正3 c 正3 and d 正3 ).

[0030] Preferably, in step 3, four low cement content levels (x) are taken both downwards and upwards for the cement. a1 x a2 xa3 , x a4 and 4 high cement content levels x a6 , x a7 , x a8 , x a9 The adopted step difference is 5%, i.e. x a4 = x a5 -5%, x a3 = x a4 -5%, x a2 = x a3 -5%, x a1 = x a2 -5% and x a6 = x a5 +5%, x a7 = x a6 +5%, x a8 = x a7 +5%, x a9 = x a8 +5%; the hydrogen peroxide, water ratio and foam stabilizer medium content levels x b5 , x c3 and x d4 adopt step difference of 0.05%, 0.05%, 0.2% respectively, to obtain 4 low content levels x b1 , x b2 , x b3 , x b4 and 4 high content levels x b6 , x b7 , x b8 , x b9 ; 2 low content levels x c1 , x c2 and 3 high content levels x c4 , x c5 , x c6 ; 4 low content levels x d1 , x d2 , x d3 , x d4 and 3 high content levels x d6 , x d7 , x d8 .

[0031] Preferably, in step 7, the large size foam lightweight soil cubic block density and unconfined compressive strength soil test, the specific steps are as follows:

[0032] Step (1): according to the respective factors determined in steps 5 and 6, three cubic foam lightweight soil test blocks with a size of 500mm*500mm*500mm are prepared, the densities of the three parallel test blocks are measured, the relative errors of the densities are calculated, if the relative errors of the densities of the three parallel test blocks are all not greater than ±2%, the average value of the densities of the three test blocks is taken as the density value of the test group; if the relative errors of the densities of the three parallel test blocks are greater than ±2%, the sample preparation and density test need to be re-performed until the relative errors of the three parallel test blocks are all not greater than ±2%, and then the average value of the densities of the three test blocks is taken as the density value of the test group (ρ 模 );

[0033] Step (2): the unconfined compressive strength test is sequentially performed on the three cubic parallel test blocks after the density test of each test group, and the average value is taken as the unconfined compressive strength test value (σ 模 ) of the test group;

[0034] Step (3): the density value (ρ 模 ) and the unconfined compressive strength test value (σ 模 ) obtained in steps (1) and (2) are compared and analyzed, if the density (ρ 模 ) of the foam lightweight soil is not equal to the initial density (ρ cr ) of the foam lightweight soil, the dosage factor (K1) which has the greatest influence on the physical properties of the foam lightweight soil needs to be adjusted, so that the simulation test results of the large size meet the requirements; if the cubic compressive strength (σ 模 ) of the foam lightweight soil does not meet the requirements of the roadbed specification, the cement dosage needs to be appropriately increased; if the density (ρ 模 ) of the foam lightweight soil is equal to the initial density (ρ cr ) of the foam lightweight soil, and the cubic compressive strength (σ 模 ) meets the requirements of the roadbed specification, it is proved that the mix proportion is feasible in the actual embankment engineering.

[0035] Compared with the prior art, the method for determining the suitable mix proportion of the high clay content foam lightweight soil for the reconstruction and expansion of the soft soil road section has the advantages that the mix proportion of the foam lightweight soil filler cannot be determined by theoretical calculation at present, the suitable mix proportion of the foam lightweight soil is determined by using a comprehensive method, so that the foam lightweight soil can meet the requirements of the relevant roadbed specifications in the roadbed construction, and the purposes of cost saving and environmental protection are achieved.

[0036] Additional aspects and advantages of the application will be better understood from the following descriptions. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a point-line graph of density value versus unconfined compressive strength test value when the density slope interval intersects the unconfined compressive strength slope interval for factor (k2) in step 5 of the present application;

[0038] Figure 2 is a point-line graph of density value versus unconfined compressive strength test value when the density slope interval is tangent to the unconfined compressive strength slope interval for factor (k2) in step 5 of the present application;

[0039] Figure 3 is a point-line graph of density value versus unconfined compressive strength test value when the density slope interval is tangent to the unconfined compressive strength slope interval for factor (k2) in step 5 of the present application;

[0040] Figure 4 is a point-line graph of density value versus unconfined compressive strength test value for water-to-material ratio factor in an embodiment of the present application;

[0041] Figure 5 is a point-line graph of density value versus unconfined compressive strength test value for cement factor in an embodiment of the present application;

[0042] Figure 6 is a point-line graph of density value versus unconfined compressive strength test value for foam stabilizer factor in an embodiment of the present application. DETAILED DESCRIPTION

[0043] The exemplary embodiments of this application are described herein with reference to the accompanying drawings, which are by way of illustration. Various details of the embodiments of the application can be modified in various ways and can employ, apart from those described, other applications, structures and techniques without departing from the spirit and scope of the present application. Therefore, the application should not be construed as being limited to the embodiments described in the following description and principles of this application can be embodied in forms beyond those explicitly described herein.

[0044] It should be noted that the terms "first", "second", and so on in the present application are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein. The implementation described in the following exemplary embodiments does not represent all implementations consistent with the present disclosure.

[0045] In addition, the term "and / or" herein is merely a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / " herein, unless otherwise specified, generally represents an "or" relationship between the associated objects.

[0046] A method for determining a suitable mixing proportion of high-clay-content foam lightweight soil for a road embankment for reconstruction and expansion of a soft soil section is described below with reference to the accompanying drawings.

[0047] The method for determining a suitable mixing proportion of high-clay-content foam lightweight soil for a road embankment for reconstruction and expansion of a soft soil section comprises the following steps:

[0048] Step 1: Determination of a modified critical density (ρ cr ) of the foam lightweight soil: According to the geotechnical parameters of each soil layer of the soft soil foundation obtained from the geotechnological survey data of the soft soil section site, and by letting the load (f0) on the ground surface = the design value of the bearing capacity of the soft soil foundation (f), the initial calculated critical density (ρ'3) of the foam lightweight soil is calculated, and the first calculated ground settlement (S1) is calculated according to the initial calculated critical density (ρ'3) of the foam lightweight soil and the design height (h) of the embankment. If the first calculated ground settlement (S1) is greater than the design required ground settlement (S0), the initial calculated critical density (ρ'3) of the foam lightweight soil is taken as the critical density (ρ cr ) and is reduced to obtain the second calculated critical density (ρ'3'), and then the second calculated ground settlement (S2) is calculated according to the second calculated critical density (ρ'3') and the design height (h) of the embankment. If the second calculated ground settlement (S2) is greater than the design required ground settlement (S0), the above steps are repeated to calculate the ith calculated ground settlement (S i ) and compare it with the design required ground settlement (S0); if the ith calculated ground settlement (S i ) is less than or equal to the design required ground settlement (S0), the calculated critical density (S i ) that first meets the requirement is taken as the critical density (ρ cr ) to determine the modified critical density (ρ cr ) of the foam lightweight soil.

[0049] In step 1, the specific calculation formula (2) of the load (f0) on the ground surface is: f0= (ρ1·h1+ρ2·h2+ρ3·h3)·g+P; the specific calculation formula (3) of the design filling height (h3) of the foam lightweight soil is: h3=h-h1-h2; and the specific calculation formula (4) of the initial calculated critical density (ρ'3) of the foam lightweight soil is: ρ'3= ((f-P) / g-ρ1·h1-ρ2·h2) / h3; in the formula (2), formula (3), and formula (4), ρ1 is the density of the material of the pavement structure layer (kg / m 3 ); ρ2 is the density of the upper embankment filler (kg / m 3 ); and ρ3 is the initial value of the critical density of the foam lightweight soil (kg / m 3h1 is the height of the pavement structure layer (m); h2 is the height of the upper embankment (m); h3 is the design filling height of the foamed lightweight soil (m); P is the pavement load of the road.

[0050] In step 1, the i-th calculation of foundation settlement (S) is performed. i The specific calculation formula (5) is as follows: In formula (5): S i Let be the foundation settlement (m) for the i-th verification, i = 1, 2, 3, 4; Δσ be the load applied to the subgrade (MPa), Δσ = (ρ1·h1 + ρ2·h2 + ρ'3·h3)·g + P; E be the elastic modulus of the foundation soil (MPa); h be the height of the embankment (m); C c denoted as the compressibility index of the foundation soil; e0 is the initial void ratio of the foundation soil; and e is the final void ratio of the foundation soil.

[0051] In step 1, the foundation settlement (S) is checked each time. i When the foundation settlement exceeds the design requirement (S0), the initial calculated critical density of the foamed lightweight soil decreases by 0.2 g / cm³. 3 ).

[0052] It should be noted that if the foundation settlement in the fourth verification (S4) is still greater than the design requirement (S0), based on existing experience, the critical density ρ of the foam-modified foundation obtained after the fifth verification of foundation settlement (S4) will be... cr It is very likely to be lower than 0.8g / cm³ 3 Furthermore, because the critical density is below 0.8 g / cm³ 3 It is difficult to fully guarantee that the construction strength of foamed lightweight soil meets the requirements of the subgrade strength. Therefore, in this case, for the sake of engineering safety, it is not recommended to use foamed lightweight soil as subgrade fill for the embankment of this soft soil foundation section.

[0053] Step 2: Determining the order of influence of admixture factors on the strength and density of foamed lightweight soil: Referring to relevant data on improved soil, the median values ​​of the commonly used admixture ranges for cement, hydrogen peroxide, water-to-material ratio, and foam stabilizer in improved soil were obtained as the median admixture levels for the four admixture factors: a. 正2 b 正2 c 正2 and d 正2 Cement, hydrogen peroxide, water-to-material ratio, and foam stabilizer are each selected from two different levels, one lower and one higher (a) for dosage. 正1 b 正1 c 正1 and d 正1 ) and a high doping level (a 正3 b 正3 c正3 and d 正3 );

[0054] Then according to the above four factors of the amount of data to make orthogonal test table (Table 1), Table 1 as follows:

[0055] Table 1 4 factors 3 levels of orthogonal test table

[0056]

[0057]

[0058] According to Table 1, 9 groups of foam lightweight soil cubic test block density determination and and unconfined compressive strength of soil test, respectively, the density of 3 foam lightweight soil cubic parallel test block of test group 1 to test group 9 is measured, the average value is calculated to obtain the density value of each group of orthogonal test: ρ 正1 , ρ 正2 , ρ 正3 … ρ 正9 ; the unconfined compressive strength test of 3 foam lightweight soil cubic parallel test block of test group 1 to test group 9 after density determination is carried out, and the average value is taken as the unconfined compressive strength test value of the group of orthogonal test σ 正1 , σ 正2 , σ 正3 … σ 正9 ;

[0059] According to the density determination results, the density of foam lightweight soil (ρ 正 ) is analyzed by range, and the density range value of each amount factor is obtained: the density range value of cement R' A , the density range value of hydrogen peroxide R' B , the density range value of water material ratio R' C , the density range value of foam stabilizer R' D ; according to the strength test results, the compressive strength of foam lightweight soil (σ 正 ) is analyzed by range, and the compressive strength range value of each amount factor is obtained: the compressive strength range value of cement R” A , the compressive strength range value of hydrogen peroxide R” B , the compressive strength range value of water material ratio R” C , the compressive strength range value of foam stabilizer R” D ;

[0060] According to the density range value and the compressive strength range value of each amount factor, the weighted coefficient w j ' of each amount factor on the density of foam lightweight soil and the weighted coefficient w” j of each amount factor on the compressive strength of foam lightweight soil are calculated respectively.That is, the density weighting coefficients of cement, hydrogen peroxide, water-to-material ratio, and foam stabilizer are obtained in the following order: w' A w' B w' C w' D And obtain the compressive strength weighting coefficient w of cement, hydrogen peroxide, water-material ratio and foam stabilizer. A 、w” B 、w” C 、w” D Then, using the weighted coefficient method, the effect of each admixture factor on the density (ρ) of the foamed lightweight soil was calculated. 正 ) and compressive strength (σ 正 The comprehensive influence coefficient w) j That is, the comprehensive influence coefficients of cement, hydrogen peroxide, water-to-material ratio, and foam stabilizer are w, respectively. A w B w C w D Based on the comprehensive influence coefficient, the order of influence of four dosage factors—cement dosage, hydrogen peroxide dosage, water-to-material ratio, and foam stabilizer—on the compressive strength and density of foamed lightweight soil was determined.

[0061] Specifically, in step 2, the density determination of the foamed lightweight soil cube specimens and the geotechnical test for unconfined compressive strength are carried out as follows:

[0062] Step (1): For each group of tests, three 100mm×100mm×100mm foamed lightweight soil cubes should be prepared according to the dosage levels in Table 1 for parallel tests. The density of the three parallel test blocks in test group 1 should be measured, and the relative error of their density should be calculated. If the relative error of the density of the three parallel test blocks is not greater than ±2%, the average density of the three test blocks should be taken as the density value of the test group. If the relative error of the density of the three parallel test blocks is greater than ±2%, the samples should be prepared again and the density test should be carried out until the relative error of the three parallel test blocks is not greater than ±2%. Then the average density of the three test blocks should be taken as the density value of the orthogonal test group.

[0063] Step (2): Following step (1), determine the density of three parallel cubic test blocks of foamed lightweight soil from test groups 2 to 9, and calculate the average value to obtain the density value of each group of orthogonal tests: ρ 正1 ρ 正2 ρ 正3 …ρ 正9 ;

[0064] Step (3): Conduct unconfined compressive strength tests on the three parallel cubic test blocks after density measurement in each group of orthogonal experiments, and take the average value as the unconfined compressive strength test value of that group of orthogonal experiments, and record it as σ. 正1 σ正2 σ 正3 …σ 正9 .

[0065] In step 2, the weighting coefficient w for the influence of each admixture factor on the density of the foamed lightweight soil is... j The specific calculation formula (6) is as follows: Weighting coefficient w for the influence of various admixture factors on the compressive strength of foamed lightweight soil j The specific calculation formula (7) for “” is as follows: The comprehensive influence coefficient w of various admixture factors on the density and compressive strength of foamed lightweight soil j The specific calculation formula (8) is: w j =0.5*w' j +0.5*w” j ;In formulas (6), (7), (8): w' j R' is the density weighting coefficient; j The density range for each doping factor; w” j R” is the compressive strength weighting factor. j The range of compressive strength for each admixture factor; w j is the comprehensive influence coefficient; j represents the doping factors A, B, C, and D; w' j w” represents the density weighting coefficient for each doping factor j; j is the compressive strength weighting coefficient for each doping factor j.

[0066] And in step 2, the cement is taken at a low admixture level both downwards and upwards (a) 正1 ) and a high doping level (a 正3 The increments for hydrogen peroxide, water-to-material ratio, and foam stabilizer were 10%, with increments of 0.1%, 0.05%, and 0.2% respectively, resulting in low dosage levels (b) for these components. 正1 c 正1 and d 正1 ) and high doping level (b 正3 c 正3 and d 正3 ).

[0067] Step 3: Determining the suitable mix proportion of foamed lightweight soil: Consult relevant information on improved soil and obtain the typical cement dosage range a1-a in the improved soil. n The median value a n / 2 is used as the intermediate admixture level of cement, denoted as x. a5 , that is, x a5 =an / 2, and use graded differences to take 4 low cement content levels downwards and upwards respectively. a1 x a2 xa3 , x a4 and 4 high cement content levels x a6 , x a7 , x a8 , x a9 ; the medium content levels x b5 , x c3 and x d4 of hydrogen peroxide, water-material ratio and foam stabilizer in the foamed lightweight soil are obtained, and the difference is used to obtain 4 low content levels x b1 , x b2 , x b3 , x b4 and 4 high content levels x b6 , x b7 , x b8 , x b9 ; the water-material ratio has 2 low content levels x c1 , x c2 and 3 high content levels x c4 , x c5 , x c6 ; the foam stabilizer has 4 low content levels x d1 , x d2 , x d3 , x d4 and 3 high content levels x d6 , x d7 , x d8 ;

[0068] Specifically, in step 3, the cement takes 4 low cement content levels x a1 , x a2 , x a3 , x a4 and 4 high cement content levels x a6 , x a7 , x a8 , x a9 downward and upward respectively, and the difference used is 5%, i.e. x a4 =x a5 -5%, x a3 =x a4 -5%, x a2 =x a3 -5%, x a1 =x a2 -5% and x a6 =x a5 +5%, x a7 =x a6 +5%, x a8 =x a7 +5%, x a9 =x a8 +5%; the medium content levels xb5 , x c3 and x d4 Sequentially using 0.05%, 0.05%, 0.2% of the level difference, get hydrogen peroxide 4 low levels of x b1 , x b2 , x b3 , x b4 And 4 high levels of x b6 , x b7 , x b8 , x b9 ; water ratio 2 low levels of x c1 , x c2 And 3 high levels of x c4 , x c5 , x c6 ; foam stabilizer 4 low levels of x d1 , x d2 , x d3 , x d4 And 3 high levels of x d6 , x d7 , x d8 .

[0069] Step 4: According to the comprehensive influence of the dosage factors obtained in step 2, the order from large to small is: factor (K1), factor (K2), factor (K3), factor (K4), and single factor test is carried out in turn from K1 to K4; factor (K1) according to the dosage value a1-a n And using the control variable method, the dosage values of the remaining three factors are all taken as the median values b n / 2 , c n / 2 , d n / 2 , design several soil tests of foam lightweight soil cube density and unconfined compressive strength, find out the foam lightweight soil test density (ρ a ) closest to the critical density (ρ cr ) of foam lightweight soil according to the test results, and judge whether the unconfined compressive strength σ a of foam lightweight soil at this density meets the requirements according to the requirements of roadbed specification; if the unconfined compressive strength of foam lightweight soil meets the requirements, select the dosage value at this density as the appropriate dosage value (a) of factor (K1); if the unconfined compressive strength does not meet the requirements of roadbed specification, the dosage value of factor (K1) needs to be appropriately increased;

[0070] Step 5: factor (K2) according to the dosage value b1-b n , the dosage value of factor (K1) is taken as the appropriate dosage value (a) and the dosage values of the remaining two factors are all taken as the median values c n / 2 , d n / 2, a series of soil tests of density and unconfined compressive strength of foam lightweight soil cubic test blocks are designed, and according to the test results, the density values of each group of single-factor tests of the factor (K2) are sequentially recorded as ρ b1 , ρ b2 , ρ b3 … ρ b9 , the unconfined compressive strength test values of each group of tests are sequentially recorded as σ b1 , σ b2 , σ b3 … σ b9 , and the density values and unconfined compressive strength test values are plotted into a point-line graph, as shown in Figure 1 , Figure 2 and Figure 3 , the density slope of each dosage value interval is sequentially calculated as and the unconfined compressive strength slope is sequentially The formula (1) is as follows: , wherein n is the test group number; if the experimental density index ρ bn > ρ cr + 0.2 (g / cm 3 ), the interval is excluded; the density slope and the unconfined compressive strength slope are sorted from large to small, and the intervals with the top three slopes are marked; as shown in Figure 1 , if the two slope intervals intersect, the dosage value at the midpoint of the interval is taken as the appropriate dosage value (b); as shown in Figure 2 , if the two slope intervals are tangent, the dosage value at the tangent point is taken as the appropriate dosage value (b); as shown in Figure 3 , if the two slope intervals are apart, the dosage value at the minimum density of the interval with the maximum slope of the test density (ρ b ) curve is selected as the appropriate dosage value (b), to obtain the appropriate dosage value (b) of the factor (K2);

[0071] Step 6: According to step 5, foam lightweight soil cubic test block density and unconfined compressive strength soil tests and data analysis are sequentially performed on the factors (K3) and (K4) to obtain the appropriate dosage value (c) of the factor K3 and the appropriate dosage value (d) of the factor K4.

[0072] Step 7: According to the appropriate mix proportion of foam lightweight soil determined in steps 5 and 6, large-size foam lightweight soil cubic test block density and unconfined compressive strength soil tests are performed to verify the feasibility of foam lightweight soil in actual engineering.

[0073] Specifically, in step 7, the large-size foam lightweight soil cubic test block density and unconfined compressive strength soil tests have the following specific steps:

[0074] Step (1): Prepare three 500mm×500mm×500mm cubes of foamed lightweight soil for parallel tests according to the appropriate dosage values ​​of each factor determined in Steps 5 and 6. Measure the density of the three parallel test blocks and calculate their relative density error. If the relative density error of the three parallel test blocks is no greater than ±2%, the average density of the three test blocks is taken as the density value of the test group. If the relative density error of the three parallel test blocks is greater than ±2%, the samples need to be prepared again for density testing until the relative error of the three parallel test blocks is no greater than ±2%. Then, the average density of the three test blocks is taken as the density value of the test group (ρ). 模 );

[0075] Step (2): Sequentially conduct unconfined compressive strength tests on three parallel cubic test blocks after density measurement for each group of tests, and take the average value as the unconfined compressive strength test value (σ) of that group of tests. 模 );

[0076] Step (3): Compare and analyze the density value (ρ modulus) and the unconfined compressive strength test value (σ) obtained in steps (1) and (2). 模 If the density of foamed lightweight soil (ρ) 模 This is not equal to the initial density (ρ) of foamed lightweight soil. cr To meet the requirements, the admixture factor (K1) that has the greatest impact on the physical properties of foamed lightweight soil needs to be adjusted so that the results of large-scale simulation tests meet the requirements; if the compressive strength of the foamed lightweight soil cube (σ) 模 If the subgrade does not meet the requirements of the roadbed specifications, the cement content needs to be appropriately increased; if the density of the foamed lightweight soil (ρ) is not met, the cement content needs to be increased. 模 ) equals the initial density of foamed lightweight soil (ρ) cr ), and the cubic compressive strength (σ 模 If the mix proportion meets the requirements of the roadbed specifications, it proves that the mix proportion is feasible in actual embankment engineering.

[0077] Example:

[0078] This embodiment is for determining the appropriate mix proportion of foamed lightweight soil for the required reconstruction and expansion of the embankment in a certain soft soil section.

[0079] I. Determination of preliminary experimental indicators:

[0080] The following parameters can be obtained from the geotechnical engineering investigation and design data of a certain soft soil road section, as shown in Table 2:

[0081] Table 2

[0082]

[0083] According to the load actually received by the soft soil foundation, the soft soil foundation bearing capacity calculation value (f0) can be calculated according to formula (2):

[0084] f0=(ρ1·h1+ρ2·h2+ρ3·h3)·g+P (2)

[0085] In formula (2), f0 is the load received by the foundation surface, f0≤f; ρ1 is the density of the road surface structure layer material (kg / m 3 ), which is taken as 2200 kg / m 3 ; ρ2 is the density of the upper embankment filler (kg / m 3 ), which is taken as 2200 kg / m 3 ; ρ3 is the initial value of the critical density of the foam light soil (kg / m 3 ); h1 is the height of the road surface structure layer (m), which is measured as 0.3 m; h2 is the height of the upper embankment (m), which is measured as 1.5 m; h3 is the design filling height of the foam light soil (m); g is the acceleration of gravity; and P is the road surface load of the road, which is taken as 15 kN according to the ordinary road surface load stress.

[0086] 2. The design height of the soft soil section embankment to be treated is measured as h=5 m, and the design filling height h3 of the foam light soil is calculated according to formula (3) to be 3.2 m;

[0087] h3=h-h1-h2 (3)

[0088] 3. Assuming that the load received by the foundation surface (f0) is the design value of the soft soil foundation bearing capacity (f), and the filling height of the foam light soil is 3.2 m, formula (4) is used for calculation:

[0089] ρ'3=((f-P) / g-ρ1·h1-ρ2·h2) / h3 (4)

[0090] The maximum density (ρ'3) of the foam light soil is obtained as ρ'3=1406 kg / m 3 .

[0091] 4. Whether the foundation settlement meets the specification requirements needs to be verified, and formula (5) is used for calculation:

[0092]

[0093] In formula (5), S is the foundation settlement (m); Δσ is the load applied by the roadbed (MPh), Δσ=(ρ1·h1+ρ2·h2+ρ'3·h3)·g+P; E is the elastic modulus of the foundation soil (MPh); h is the height of the embankment (m); C c is the compression index of the foundation soil; e0 is the initial void ratio of the foundation soil; and e is the final void ratio of the foundation soil.

[0094] 5. Substituting formula (5) gives the first calculation of the foundation settlement S1 = 5.8 cm, which does not meet the design requirement of the foundation settlement S0 = 5.5 cm, and the initial calculation of the critical density of the foam lightweight soil needs to be reduced;

[0095] 6. Let the second calculation of the critical density ρ"3 = ρ'3 - 0.2 = 1.2 (g / cm 3 ), and substitute the second calculation of the critical density ρ"3 = 1.2 g / cm 3 into formula (5) to calculate the second calculation of the foundation settlement (S2), which gives S2 = 5.6 cm, which does not meet the design requirement of the foundation settlement S0 = 5.5 cm;

[0096] 7. Continue to let the third calculation of the critical density ρ'"3 = ρ"3 - 0.2 = 1.0 (g / cm 3 ), and substitute the third calculation of the critical density ρ'"3 = 1.0 g / cm 3 into formula (5) to calculate the third calculation of the foundation settlement (S3), which gives the settlement S = 5.4 cm, which meets the design requirement of the foundation settlement S0 = 5.5 cm;

[0097] 8. Take the third calculation of the critical density of the foam lightweight soil ρ'"3 = 1.0 g / cm 3 as the critical density ρ cr .

[0098] II. Determination of the order of the influence of the mixing amount factors on the strength and density of the foam lightweight soil

[0099] The mixing amount factors that affect the density and compressive strength of the foam lightweight soil include the cement mixing amount (A), the hydrogen peroxide mixing amount (B), the water-material ratio (C), and the foam stabilizer mixing amount (D). In order to effectively reduce the experimental amount and quickly obtain the order of the influence of each mixing amount factor on the strength and density of the foam lightweight soil, orthogonal test with four factors and three levels and the density and compressive strength equal weighting coefficient method are used for analysis.

[0100] 1. Select the cement mixing amount level: refer to the relevant information of the improved soil to obtain the general mixing amount value of the cement in the improved soil, take it as the middle mixing amount, and mark it as a 正2 = 30%, and take one low mixing amount (a 正1 ) and one high mixing amount (a 正3 ) on both sides, let a 正1 = a 正2 - 10% = 20% and a 正3 = a 正2 + 10% = 40%;

[0101] 2. Select the dosage level of hydrogen peroxide: consult the relevant information of foam concrete, and get the high dosage value b of hydrogen peroxide in foam lightweight soil according to the existing experience 正3 = 0.3%, let the medium dosage value b 正2 = b 正3 - 0.1% = 0.2%, the low dosage value b 正1 = b 正3 - 0.2% = 0.1%;

[0102] 3. Select the water material ratio level: consult the relevant information of foam concrete and improved soil, take the middle value of water material ratio as c 正2 , and take one low dosage (c 正1 ) and high dosage (c 正3 ) on both sides, let c 正1 = c 正2 - 0.05 and c 正3 = c 正2 + 0.05;

[0103] 4. Select the dosage level of foam stabilizer: consult the relevant information of foam concrete, get the general dosage value of foam stabilizer in improved soil, take it as the middle dosage (d 正2 ), and d 正2 = 1%, and take one low dosage (d 正1 ) and high dosage (d 正3 ) on both sides, let d 正1 = d 正2 - 0.2% = 0.8% and d 正3 = d 正2 + 0.2% = 1.2%;

[0104] 5. Formulate orthogonal test table (Table 3);

[0105] Table 3 Orthogonal test table

[0106]

[0107] 6. According to the orthogonal test table, 9 groups of tests are carried out, and 100mm x 100mm x 100mm cubic test blocks are made for each test, and the densities of foam lightweight soil cubic test blocks of test 1 to test 9 are measured respectively 正1 = 1.415g / cm 3 , p 正2 = 1.051g / cm 3 , p 正3 = 0.76g / cm 3 , p 正4 = 1.122g / cm 3 , p 正5 = 1.053g / cm 3 , p 正6= 0.912 g / cm 3 , p 正7 = 1.031 g / cm 3 , p 正8 = 0.986 g / cm 3 , p 正9 = 0.884 g / cm 3 , and unconfined compressive strength s 正1 = 805.15 kPa, s 正2 = 327.25 kPa, s 正3 = 114.15 kPa, s 正4 = 689.15 kPa, s 正5 = 517.25 kPa, s 正6 = 713.42 kPa, s 正7 = 803.02 kPa, s 正8 = 805.25 kPa, s 正9 = 500.16 kPa

[0108] 7. Range analysis was performed on the density (p 正 ) of the foamed lightweight soil obtained from the orthogonal test, and the range values of each dosage factor were obtained: the range value R' A of the cement dosage (A) = 0.062, the range value R' B of the hydrogen peroxide dosage (B) = 0.335, the range value R' C of the water-material ratio (C) = 0.154, and the range value R' D of the foam stabilizer dosage (D) = 0.159.

[0109] 8. Range analysis was performed on the compressive strength (s 正 ) of the foamed lightweight soil obtained from the orthogonal test, and the range values of each dosage factor were obtained: the range value R' A ' of the cement dosage (A) = 296.46, the range value R' B ' of the hydrogen peroxide dosage (B) = 323.20, the range value R' C ' of the water-material ratio (C) = 287.29, and the range value R' D ' of the foam stabilizer dosage (D) = 78.38.

[0110] 9. The weighted coefficient method was used to comprehensively determine the order of the influence of the four dosage factors on the density (p 正 ) and the compressive strength (s 正 ) of the foamed lightweight soil. The weighted coefficients of the range values R' A , R' B , R' C , and R' D of the four dosage factors on the density of the foamed lightweight soil were calculated, and the weighted coefficient w' was obtained according to formula (6).A =0.087, w' B =0.472, w' C =0.217, w' D =0.224;

[0111]

[0112] In formula (6): w j ' is the weighting coefficient, j is the dosage factor A, B, C, D; R' is the range of dosage for each factor.

[0113] 10. The range value R” obtained by calculating the compressive strength of foamed lightweight soil using four admixture factors. A 、R” B 、R” C 、R” D The weight coefficients are calculated using formula (7), and the weight coefficients w” are obtained. A =0.302、w” B =0.328, w” C =0.291, w” D =0.079, the specific calculation is as follows:

[0114]

[0115] In formula (7): w” j is the weighting coefficient, j represents the dosage factors A, B, C, and D; R is the range of dosage for each factor.

[0116] 11. The weighting coefficient w for cement admixture (A) can be obtained. A =w' A +w” A =0.389, the weighting coefficient w for hydrogen peroxide dosage (B) B =w' B +w” B =0.8, the weighting coefficient w of the water-to-material ratio (C) C =w' C +w” C =0.508, the weighting coefficient w of the foam stabilizer dosage (D) D =w' D +w” D =0.303;

[0117] 12. By comparing the magnitudes of the weight coefficients, we can obtain w. B >w C >w A >w D, the order of the influence of the mixing amount factors on the physical properties of the foam light soil is: hydrogen peroxide mixing amount (B) > water-material ratio (C) > cement mixing amount (A) > foam stabilizer mixing amount (D), and single-factor experiments are performed according to this order to gradually determine the suitable mixing amount values of the mixing amount factors.

[0118] III. Determination of the suitable mixing ratio of the foam light soil

[0119] 1. In the above steps, the critical density (ρ cr ) of the foam light soil is determined, and the hydrogen peroxide mixing amount (B) has the greatest influence on the physical properties of the foam light soil, so the single-factor experiment of the hydrogen peroxide mixing amount (B) is performed first to determine the suitable mixing amount value (a).

[0120] According to the existing experience, the hydrogen peroxide mixing amount (B) is designed to have 9 mixing amount values a1 = 0.1%, a2 = 0.15%, a3 = 0.2%...a9 = 0.5%, and the remaining three mixing amount factors all take the middle values in the design range, the cement mixing amount takes 30%, the water-material ratio takes 0.55, and the foam stabilizer mixing amount takes 0.8%, 100mm×100mm×100mm cubic test blocks are made, and their densities ρ a1 = 1.036, ρ a2 = 0.982, ρ a3 = 0.957, ρ a4 = 0.924, ρ a5 = 0.872, ρ a6 = 0.788, ρ a7 = 0.724, ρ a8 = 0.685, ρ a9 = 0.648 (g / cm 3 ), and their unconfined compressive strengths σ a1 = 529.482, σ a2 = 402.256, σ a3 = 298.435, σ a4 = 253.452, σ a5 = 224.254, σ a6 = 182.245, σ a7 = 168.227, σ a8 = 157.245, σ a9 = 142.683 (kPa) are tested, according to the experimental results, it is found that the test density ρ a1 = 1.036 of the foam light soil tends to the critical density (ρ cr ) of the foam light soil, and the unconfined compressive strength σ a1 = 529.482 kPa of the foam light soil at this density meets the requirements of the roadbed design specification, therefore, the suitable mixing amount value a of the hydrogen peroxide mixing amount (B) is selected to be 0.1%.

[0121] 2. Select the water-material ratio (C) in the second order of the weight coefficient size to conduct single-factor experiment to determine the appropriate dosage value (b).

[0122] According to the existing experience, six groups of single-factor experiments are conducted on the water-material ratio (C) with the test numbers 1-6, the water-material ratio (C) values b1=0.45, b2=0.5, b3=0.55...b6=0.7, wherein the appropriate dosage value a of the hydrogen peroxide dosage (B) is 0.1%, the remaining two dosage factors are the middle values in the design range, the cement dosage (A) is 30%, and the foam stabilizer dosage (D) is 0.8%. The 100mm×100mm×100mm cubic test blocks are made to test the density ρ b1 =1.278, ρ b2 =1.058, ρ b3 =0.907, ρ b4 =0.878, ρ b5 =0.854, ρ b6 =0.813 (g / cm 3 ), and the unconfined compressive strength σ b1 =762.514, σ b2 =632.145, σ b3 =482.354, σ b4 =395.214, σ b5 =375.245, σ b6 =342.325 (kPa), and a dot line graph is drawn to analyze the appropriate dosage value (b) by using the method of two-index slope intersection.

[0123] The density and compressive strength slopes of each dosage value interval are calculated by formula (1), and the interval with larger density and compressive strength slopes is marked. If the test density index ρ b >ρ cr +0.2 (g / cm 3 ) in the interval, the interval is excluded, and then the appropriate dosage value is selected;

[0124]

[0125] In formula (1), n is the test number.

[0126] For the cubic compressive strength slope, kσ b1 =2607.38, kσ b2 =2995.82, kσ b3 =1742.8, kσ b4 =399.38, kσ b5 =658.4, and for the density slope, kρ b1=4.4, kρ b2 =3.02, kρ b3 =0.58, kρ b4 =0.48, kρ b5 =0.82, marking the range where the slope of density and compressive strength is relatively large, such as Figure 4 As shown, due to ρ b1 =1.278 (g / bm) 3 () greater than the critical density ρ of foamed lightweight soil cr +0.2 (g / cm) 3 After excluding that point, it can be seen that the two intervals intersect between a water-to-material ratio of 0.5 and 0.55. The midpoint of this interval is selected, and the unconfined compressive strength σ at the midpoint of this interval is... b中 =557.249kPa meets the requirements of the roadbed specification, so the suitable value of water-material ratio (C) b is 0.525.

[0127] 3. Select the cement dosage (A) that is third in the weighting order to conduct a single-factor experiment to determine the appropriate dosage value (c).

[0128] Based on existing experience, nine single-factor experiments were conducted on the cement admixture (A), numbered 1 to 9. The cement admixture (A) values ​​were c1 = 10%, c2 = 15%, c3 = 20%, ... c9 = 50%. The suitable value a for the hydrogen peroxide admixture (B) was 0.1%, the suitable value b for the water-cement ratio (C) was 0.525, and the remaining foam stabilizer admixture (D) was 0.8%. 100mm × 100mm × 100mm cubic specimens were prepared, and their density ρ was tested. c1 =1.524, ρ c2 =1.398, ρ c3 =1.294, ρ c4 =1.204, ρ c5 =1.056, ρ c6 =1.092, ρ c7 =1.097, ρ c8 =1.125, ρ c9 =1.142 (g / cm) 3 ), and unconfined compressive strength σ c1 =324.158, σ c2 =376.215, σ c3 =444.339, σ c4 =495.215, σ c5 =529.428, σ c6 =634.254, σ c7 =728.480, σ c8 =998.415, σ c9= 1277.674 (kPa), and plotted as a dotted line, the appropriate dosage value (c) is analyzed by the method of double-index slope intersection.

[0129] The density and compressive strength slope of each dosage value interval is calculated by formula (9), and the interval with larger density and compressive strength slope is marked. If the test density index ρ c >ρ cr + 0.2 (g / cm 3 ), the interval is excluded, and then the appropriate dosage value is selected;

[0130]

[0131] In the formula: n---test number;

[0132] For the compressive strength slope of the cube, kσ c1 = 1041.14, kσ c2 = 1362.48, kσ c3 = 1017.52, kσ c4 = 684.26, kσ c5 = 2096.52, kσ c6 = 1884.52, kσ c7 = 5398.7, kσ c8 = 5585.18, and for the density slope, kρ c1 = 2.52, kρ c2 = 2.08, kρ c3 = 1.80, kρ c4 = 2.96, kρ c5 = 0.72, kρ c6 = 0.1, kρ c7 = 0.56, kρ c8 = 0.34, the interval with larger density and compressive strength slope is marked, as shown in Figure 5 Since ρ c1 = 1.524, ρ c2 = 1.398, ρ c3 = 1.294 (g / cm 3 ) are all greater than the critical density of the foam lightweight soil ρ cr + 0.2 (g / cm 3 ), the interval is excluded, and it can be seen that the two intervals intersect at a cement dosage of 30%, and the unconfined compressive strength σ c5 = 529.428 kPa meets the requirements of the roadbed specification, so the appropriate dosage value c of the cement dosage (A) is 30%.

[0133] 4. Select the minimum amount of stabilizing agent (D), and conduct 8 single factor experiments on the amount of stabilizing agent (D), test number 1-8. According to the existing experience, the amount of stabilizing agent (D) is d1=0%, d2=0.2%, d3=0.4%...d8=1.4%. The suitable value of hydrogen peroxide (B) is a=0.1%, the suitable value of water-cement ratio (C) is b=0.525, the suitable value of cement (A) is c=30%. Make 100mmx100mmx100mm cubic test blocks, and test their densities ρ d1 =1.524, ρ d2 =1.501, ρ d3 =1.425, ρ d4 =1.324, ρ d5 =1.128, ρ d6 =1.016, ρ d7 =0.894, ρ d8 =0.882(g / cm 3 ), and their unconfined compressive strengths σ d1 =923.742, σ d2 =878.548, σ d3 =702.245, σ d4 =600.145, σ d5 =568.214, σ d6 =548.274, σ d7 =350.142, σ d8 =212.247(kPa), and draw a dotted line graph. The suitable amount (d) is analyzed by the method of two index slope intersection.

[0134] Calculate the density and compressive strength slope of each amount value interval by formula (10), and mark the interval with larger density and compressive strength slope. If the test density index ρ d >ρ cr +0.2(g / cm 3 ) in the interval, exclude the interval, and then select the suitable amount value.

[0135]

[0136] In formula (10) : n---test number;

[0137] For the cubic compressive strength slope, kσ d1 =225.97, kσ d2 =881.51, kσ d3 =510.5, kσ d4 =159.65, kσ d5 =99.7, kσd6 =990.66, kσ d7 =689.47, for the density slope we have kρ d1 =0.12, kρ d2 =0.38, kρ d3 =0.51, kρ d4 =0.98, kρ d5 =0.56, kρ d6 =0.61, kρ d7 =0.06, marking the range where the slope of density and compressive strength is large, such as Figure 6 As shown, due to ρ d2 =1.501, ρ d3 =1.425, ρ d4 =1.324 (g / cm) 3 All are greater than the critical density ρ of foamed lightweight soil. cr +0.2 (g / cm) 3 After excluding that interval, it can be seen that the two intervals intersect between 1.0% and 1.2% of the foam stabilizer dosage. The midpoint of this interval is selected, and the unconfined compressive strength σ at the midpoint of this interval is... d中 =449.208kPa meets the requirements of the roadbed specification, so the appropriate value of foam stabilizer dosage (D) is 1.1%.

[0138] 5. After comprehensive analysis, the appropriate values ​​for cement content (A) c in the foamed lightweight soil mix proportion are 30%, hydrogen peroxide content (B) a is 0.1%, water-to-material ratio (C) b is 0.525, and foam stabilizer content (D) d is 1.1%.

[0139] IV. After finding the suitable mix proportion of foamed lightweight soil using the above method, a large-scale simulation test needs to be conducted on this mix proportion. Based on the suitable values ​​for cement content (A) (c) being 30%, hydrogen peroxide content (B) being 0.1%, water-to-material ratio (C) being 0.525, and foam stabilizer content (D) being 1.1%, a 100cm × 100cm × 100cm cube model should be constructed. After curing according to specifications, its density ρ should be tested. 模 =1.056g / cm 3 Unconfined cubic compressive strength σ 模 = 559.428 kPa, which meets the density (ρ) requirement of large-scale model tests for foamed lightweight soil. 模 The initial density (ρ) of the foamed lightweight soil is close to that of the initial soil. cr Furthermore, the unconfined cubic compressive strength meets the requirements of the roadbed specifications, proving that this mix proportion is feasible in actual embankment engineering and also providing certain reference value for field process tests.

[0140] The above detailed description does not limit the scope of the application. Various modifications, combinations, sub-combinations and alternatives can be made to the detailed embodiment disclosed herein without departing from the spirit and the principles of the application. Any modification, equivalent replacement or improvement made within the spirit and principles of the application shall fall within the scope of the application.

Claims

1. A method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section, characterized in that, Comprising the following steps: Step 1: Critical density ρ of improved foamed lightweight soil cr Determination: Based on the geotechnical parameters of each soil layer in the soft soil foundation obtained from the geotechnical engineering investigation data of the soft soil section, and assuming that the load on the foundation surface f0 = the design value of the bearing capacity of the soft soil foundation f, the initial critical density of the foamed lightweight soil is calculated. Based on the initial calculation of the critical density of foamed lightweight soil Based on the embankment design height h, the first verification foundation settlement S1 is calculated. If the first verification foundation settlement S1 is greater than the design required foundation settlement S0, then the initial calculation critical density of the foamed lightweight soil is taken. Critical density ρ cr And reduce the initial calculated critical density of foamed lightweight soil. The second calculation of the critical density was obtained. Then, based on the second calculation of the critical density Given the embankment design height h, calculate the second verification of foundation settlement S2. If the second verification of foundation settlement S2 is greater than the design requirement of foundation settlement S0, repeat the above steps to calculate the i-th verification of foundation settlement S. i And compare it with the foundation settlement S0 required by the design; If the foundation settlement S of the i-th checking is less than or equal to the design requirement foundation settlement S0, the critical density calculated at the first time meeting the requirement is taken as the critical density p i less than or equal to the design requirement foundation settlement S0, the critical density calculated at the first time meeting the requirement is taken as the critical density p cr , to determine the improved critical density p of the foam light soil cr ; Step 2: Determination of the order of the influence of the factors on the strength and density of the foam lightweight soil: The median values of the commonly used dosage ranges of cement, hydrogen peroxide, water-solids ratio and foam stabilizer in modified soil were obtained in sequence as the median dosage levels of the four factors of cement, hydrogen peroxide, water-solids ratio and foam stabilizer, respectively, a 正2 , b 正2 , c 正2 and d 正2 . One low dosage level (a 正1、 b 正1 , c 正1 and d 正1 ) and one high dosage level (a 正3、 b 正3 , c 正3 and d 正3 ) were taken for each of the four factors in a step-down and step-up manner, respectively. Then according to the above four factors of the amount of data to make orthogonal test table of low, medium, high level of mixing amount of foam lightweight soil cubic test block density test and unconfined compressive strength of soil test, respectively, the density of 3 foam lightweight soil cubic parallel test block of test group 1 to test group 9 is measured, the average value is calculated to obtain the density value of each group of orthogonal test: ρ 正1 , ρ 正2 , ρ 正3 …ρ 正9 ; the unconfined compressive strength test of 3 foam lightweight soil cubic parallel test block of test group 1 to test group 9 after density determination is carried out, and the average value is taken as the unconfined compressive strength test value of the group of orthogonal test σ 正1 , σ 正2 , σ 正3 …σ 正9 ; According to the density test results, the density of the foam light soil ρ 正 is analyzed by range analysis, and the density range values of each mixing amount factor are obtained: the density range value of cement , the density range value of hydrogen peroxide , the density range value of water-material ratio , and the density range value of foam stabilizer ; according to the strength test results, the compressive strength of the foam light soil σ 正 is analyzed by range analysis, and the compressive strength range values of each mixing amount factor are obtained: the compressive strength range value of cement , the compressive strength range value of hydrogen peroxide , the compressive strength range value of water-material ratio , and the compressive strength range value of foam stabilizer ; Based on the density range and compressive strength range of each admixture factor, the weighting coefficients for the influence of each admixture factor on the density of foamed lightweight soil were calculated. Weighting factor for the effect on compressive strength of foamed lightweight soil That is, the density weighting coefficients of cement, hydrogen peroxide, water-to-material ratio, and foam stabilizer are obtained in the following order: , , , And obtain the compressive strength weighting coefficients of cement, hydrogen peroxide, water-to-material ratio and foam stabilizer. , , , Then, using the weighted coefficient method, the effect of each admixture factor on the density ρ of the foamed lightweight soil was calculated. 正 With compressive strength σ 正 Comprehensive influence coefficient The comprehensive influence coefficients of cement, hydrogen peroxide, water-to-material ratio, and foam stabilizer are respectively obtained. , , , Based on the comprehensive influence coefficient, the order of influence of four dosage factors—cement dosage, hydrogen peroxide dosage, water-to-material ratio, and foam stabilizer—on the compressive strength and density of foamed lightweight soil was determined. Step 3: Determination of suitable mixing ratio of foam lightweight soil: refer to the relevant information of modified soil, sequentially obtain the usual mixing amount range a1-a of cement in modified soil n The median value a n / 2 of the median value a a5 of cement mixing amount is recorded as x a5 , that is, x a1 = an / 2, and take 4 low cement mixing amount levels x a2 , x a3 , x a4 , x a6 and 4 high cement mixing amount x a7 , x a8 , x a9 respectively by using the interval difference; obtain the median mixing amount levels x b5 , x c3 and x d4 of hydrogen peroxide, water ratio and foam stabilizer in foam lightweight soil, and take 4 low mixing amount levels x b1 , x b2 , x b3 , x b4 and 4 high mixing amount levels x b6 , x b7 , x b8 , x b9 of hydrogen peroxide by using the interval difference; 2 low mixing amount levels x c1 , x c2 and 3 high mixing amount levels x c4 , x c5 , x c6 of water ratio; 4 low mixing amount levels x d1 , x d2 , x d3 , x d4 and 3 high mixing amount levels x d6 , x d7 , x d8 of foam stabilizer Step 4: According to the order from large to small of the comprehensive influence of the factors in step 2, the single factor test is carried out from K1 to K4 in turn; the factor K1 takes the values a1-a4 according to the dosage value a1-a4 n , the other three factors take the median value b n / 2 , c n / 2 , d n / 2 , and a number of soil tests of the density and unconfined compressive strength of the foam lightweight soil cubic block are designed, the test density p cr of the foam lightweight soil closest to the critical density p a of the foam lightweight soil is found out according to the test results, and whether the unconfined compressive strength s a of the foam lightweight soil at the density meets the requirements is judged according to the requirements of the roadbed specification; if the unconfined compressive strength of the foam lightweight soil meets the requirements, the dosage value at the density is selected as the suitable dosage value a of the factor K1; if the unconfined compressive strength does not meet the requirements of the roadbed specification, the dosage value of the factor K1 needs to be increased appropriately; Step 5: the dosage value of factor K2 is b1-b n , the dosage value of factor K1 is the appropriate dosage value a, and the dosage values of the remaining two factors are all the median value c n / 2 , d n / 2 , a number of foam lightweight soil cubic test block densities and unconfined compressive strengths are designed, and according to the test results, the density values of each group of single-factor tests of factor K2 are sequentially denoted as ρ b1 , ρ b2 , ρ b3 …ρ b9 , the unconfined compressive strength test values corresponding to each group of tests are sequentially denoted as σ b1 , σ b2 , σ b3 …σ b9 , and the density values and unconfined compressive strength test values are plotted into a point-line graph, and the density slope of each dosage value interval is sequentially calculated according to formula (1) as follows: 、 、 … and the unconfined compressive strength slope is sequentially as follows: 、 、 … , formula (1) is as follows: , , wherein n is the test group number; if the experimental density index ρ bn >ρ cr +0.2 (g / cm 3 ), the interval is excluded; the density slope and the unconfined compressive strength slope are sorted from large to small, and the intervals with the top three slopes are marked; if the two slope intervals intersect, the dosage value at the midpoint of the interval is taken as the appropriate dosage value b; if the two slope intervals are tangent, the dosage value at the tangent point is taken as the appropriate dosage value b; if the two slope intervals are apart, the dosage value at the minimum density of the interval with the maximum slope of the ρ b curve is taken as the appropriate dosage value b, so as to obtain the appropriate dosage value b of factor K2; Step 6: According to step 5, the foam light soil cube test block density and unconfined compressive strength of geotechnical test and data analysis are carried out on factors K3 and K4 in turn, and the suitable dosage value c of factor K3 and the suitable dosage value d of factor K4 are obtained; Step 7: According to the suitable mixing proportion of foam light soil determined in step 5 and step 6, the soil test of large size foam light soil cube test block density and unconfined compressive strength is carried out to verify the feasibility of foam light soil in actual engineering.

2. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 1, the specific calculation formula (2) of the load f0 on the ground surface is: The specific calculation formula (3) of the design filling height of the foamed lightweight soil is: ;​ Initial calculation of critical density of foamed lightweight soil The specific calculation formula (4) is: ; In formula (2), formula (3) and formula (4), ρ1 is the density of the material of the road surface structure layer (kg / m 3 ); ρ2 is the density of the upper embankment filler (kg / m 3 ); ρ3 is the initial value of the critical density of the foamed lightweight soil (kg / m 3 ); h1 is the height of the road surface structure layer (m); h2 is the height of the upper embankment (m); h3 is the designed filling height of the foamed lightweight soil (m); and P is the road surface load of the road.

3. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 1, the i-th checking foundation settlement amount S i The specific calculation formula (5) is: In formula (5), S i The i-th checking foundation settlement amount (m), i=1, 2, 3, 4; Δσ is the load applied by the roadbed (MPa), ; E is the elastic modulus of the foundation soil (MPa); h is the height of the embankment (m); C c The compression index of the foundation soil; e0 is the initial void ratio of the foundation soil; e is the final void ratio of the foundation soil.

4. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 1, the amount of foundation settlement S is calculated at each time i The calculated critical density of the foam lightweight soil is reduced when the amount of foundation settlement S is greater than the design requirement S0 (g / cm 3 ).

5. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 2, the foam light soil cube test block density determination and the soil test of unconfined compressive strength are carried out, and the specific steps are as follows: Step (1): Each group of test needs to make 3 foam light soil cube parallel test blocks with the specification of 100mm×100mm×100mm according to the dosage level of orthogonal test table, the density of 3 parallel test blocks of test group 1 is determined, the relative error of density is calculated, if the relative error of density of 3 parallel test blocks is not greater than ±2%, the average value of density of 3 test blocks is taken as the density value of the test group; if the relative error of density of 3 parallel test blocks is greater than ±2%, the sample needs to be made again for density test, until the relative error of 3 parallel test blocks is not greater than ±2%, then the average value of density of 3 test blocks is taken as the density value of the orthogonal test group; Step (2): The density of the 3 cubic parallel test blocks of the foam light soil in test group 2 to test group 9 in step (1) is determined, and the average value is calculated to obtain the density value of each group of orthogonal tests: ρ 正1 , ρ 正2 , ρ 正3 … ρ 正9 ; Step (3): sequentially perform unconfined compressive strength test on each group of three cubic parallel test specimens after orthogonal test density determination, and take the average value as the unconfined compressive strength test value of the group, sequentially recorded as σ 正1 , σ 正2 , σ 正3 … σ 正9 .

6. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 2, the weighted coefficient of each mixing amount factor on the density of foam lightweight soil The specific calculation formula (6) of is: In step 2, the weighted coefficient of each mixing amount factor on the compressive strength of foam lightweight soil The specific calculation formula (7) of is: In step 2, the comprehensive influence coefficient of each mixing amount factor on the density and compressive strength of foam lightweight soil The specific calculation formula (8) of is: In formula (6), (7), and (8): is the density range value of each mixing amount factor; is the compressive strength range value of each mixing amount factor; is the comprehensive influence coefficient; j is the mixing amount factor A, B, C, or D; is the density weight coefficient of each mixing amount factor j; is the compressive strength weight coefficient of each mixing amount factor j.

7. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 2, cement is taken at two low-dosage levels, one downward and one upward. 正1 and a high doping level a 正3 The increments were 10%, with hydrogen peroxide, water-to-material ratio, and foam stabilizer used in increments of 0.1%, 0.05%, and 0.2% respectively, to obtain low dosage levels (b) for hydrogen peroxide, water-to-material ratio, and foam stabilizer. 正1 c 正1 and d 正1 ) and high doping level (b 正3 c 正3 and d 正3 ).

8. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 3, the cement takes 4 low cement content levels x a1 , a2 , a3 , a4 and 4 high cement content levels x a6 , a7 , a8 , a9 respectively, with a difference of 5% between each level , , , and , , , ; the hydrogen peroxide, water ratio and foam stabilizer take 4 low content levels x b5 , c3 , d4 respectively, with a difference of 0.05%, 0.05%, 0.2% between each level, resulting in 4 low content levels x b1 , b2 , b3 , b4 and 4 high content levels x b6 , b7 , b8 , b9 for hydrogen peroxide c1 , c2 , c4 , c5 , c6 for water ratio d1 , d2 , d3 , d4 and 3 high content levels x d6 , d7 , d8 for foam stabilizer.

9. The method for determining the suitable mixing proportion of high clay content foam lightweight soil for the reconstruction and extension embankment of soft soil section according to claim 1, characterized in that, In step 7, the soil test of large size foam light soil cube test block density and unconfined compressive strength is carried out, and the specific steps are as follows: Step (1): According to the respective factors determined in steps 5 and 6, three foam lightweight soil cubes with a size of 500 mm x 500 mm x 500 mm are prepared in parallel, and the densities of the three parallel test blocks are measured, the relative errors of the densities are calculated, if the relative errors of the densities of the three parallel test blocks are all not greater than ±2%, the average value of the densities of the three test blocks is taken as the density value of the test group; if the relative errors of the densities of the three parallel test blocks are greater than ±2%, the sample needs to be prepared again for density test until the relative errors of the three parallel test blocks are all not greater than ±2%, and then the average value of the densities of the three test blocks is taken as the density value of the test group ρ 模 ; Step (2): sequentially determine the unconfined compressive strength of each group of three cubic parallel test blocks after the test density, and take the average value as the unconfined compressive strength test value σ of the group 模 ; Step (3): Comparative analysis of the density value ρ obtained in step (1) and step (2) 模 and unconfined compressive strength test value σ 模 , if the density of the foam lightweight soil ρ 模 does not meet the requirements of the improved critical density of the foam lightweight soil ρ cr , the dosage factor K1 which has the greatest impact on the physical properties of the foam lightweight soil needs to be adjusted so that the results of the large-size simulation test meet the requirements; if the cube compressive strength of the foam lightweight soil σ 模 does not meet the requirements of the roadbed specification, the cement dosage needs to be appropriately increased; if the density of the foam lightweight soil ρ 模 meets the requirements of the improved critical density of the foam lightweight soil ρ cr , and the cube compressive strength σ 模 meets the requirements of the roadbed specification, it is proved that the mix proportion is feasible in actual embankment engineering.

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