Method for predicting pile-forming effect of soil cement mixing pile of erosion-silting phase foundation

Abstract

The invention discloses a method for predicting the pile forming effect of a soil cement mixing pile of an alluvial deposit phase foundation, which comprises the following steps of: sampling to-be-solidified sludge soil, and measuring the basic properties of the to-be-solidified sludge soil; preparing a soil cementing material, and mixing the soil cementing material with the to-be-solidified sludge soil to prepare a plurality of solidified soil test pieces; measuring the unconfined compressive strength of the solidified soil test piece and the activity index of soil cement solidified soil; construction parameters of the stirring pile are determined; a prediction model of the pile forming effect of the soil cementing material mixing pile of the erosion-silting phase foundation is constructed; and according to the constructed prediction model, the pile forming effect of the soil cement mixing pile of the alluvial deposit phase foundation is judged. By implementing the method, the pile forming effect of the alluvial deposit phase foundation soil cementing material mixing pile can be accurately predicted through a small number of indoor tests, and the engineering efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of prediction methods for mixing pile composite foundations, and particularly to a prediction method for the pile-forming effect of soil binder mixing piles in alluvial and silty foundations. Background Art

[0002] The Pearl River Delta region has the widest distribution of soft soil in Guangdong Province. Foshan is located in the hinterland of the Pearl River Delta and has typical alluvial and silty strata, mainly composed of soft soil layers such as silty clay and silty sand, with characteristics such as high water content, high organic matter content, and low bearing capacity. With the continuous advancement of the construction scale in the Pearl River Delta, reasonable and efficient soft soil treatment methods will create more possibilities for larger projects and more adverse construction conditions.

[0003] Cement-soil mixing piles are currently the most widely used soft soil reinforcement method. However, for soft soil with high water content and high organic matter content, the cement solidification effect is not good. In response to the policy call of "carbon peak and carbon neutrality", soil binders based on solid waste are increasingly being used in mixing pile composite foundations due to their excellent solidification effect, green and low-carbon characteristics, and the promotion of solid waste resource utilization.

[0004] The pile-forming effect of mixing piles is an important basis for soft foundation reinforcement. Due to the complex nature of soft soil, the varying degrees of hydration reaction between binders and different types of soft soil, and comprehensive factors such as the construction technology of mixing piles, and currently, the conclusions about the pile-forming effect of mixing piles are obtained through qualitative analysis by on-site personnel after a large number of trial piles, which consumes a large amount of human and material resources and reduces engineering efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a prediction method for the pile-forming effect of soil binder mixing piles in alluvial and silty foundations, which can accurately predict the pile-forming effect of soil binder mixing piles in alluvial and silty foundations through a small number of laboratory tests and improve engineering efficiency.

[0006] To solve the above problems, the present invention discloses a prediction method for the pile-forming effect of soil binder mixing piles in alluvial and silty foundations, including the following steps:

[0007] Sampling the soil to be solidified and measuring the basic properties of the soil to be solidified;

[0008] Preparing a soil binder, mixing it with the soil to be solidified, and making a plurality of solidified soil specimens;

[0009] Measuring the unconfined compressive strength of the solidified soil specimens and the activity index of the soil binder solidified soil;

[0010] Determining the construction parameters of the mixing piles;

[0011] Build a prediction model for the forming effect of soil binder mixing piles in alluvial and sedimentary foundation soils;

[0012] Judge the forming effect of soil binder mixing piles in alluvial and sedimentary foundation soils according to the built prediction model.

[0013] As an improvement of the above technical solution, the basic properties of the soil to be solidified include the natural water content h w , clay content h c , organic matter content h org ;

[0014] The construction parameters of the mixing pile include the total number of times y of the mixing pile's downward penetration and upward lifting, the total number of times x of the slurry injection during the mixing pile's downward penetration and upward lifting, the amount of soil binder per linear meter w t , slurry injection flow rate L, the average speed of the mixing pile's downward penetration and upward lifting The density ρ of the soil binder slurry, the water consumption v per linear meter w , and the number of mixing times N at any point in the soil within the reinforcement range.

[0015] As an improvement of the above technical solution, the prediction model for the forming effect of soil binder mixing piles in alluvial and sedimentary foundation soils includes:

[0016] Establish a first relational expression for the first variable;

[0017] Establish a second relational expression for the second variable;

[0018] Establish a third relational expression for the third variable according to the unconfined compressive strength of the solidified soil specimen;

[0019] Construct a prediction model for the forming effect of soil binder mixing piles in alluvial and sedimentary foundation soils according to the weights of the first variable, the second variable, and the third variable and the natural water content of the soil to be solidified.

[0020] As an improvement of the above technical solution, the first relational expression is as follows:

[0021] P1 = S AI -(h c +h org )

[0022] Wherein, h c is the clay content of the soil to be solidified, h org is the organic matter content of the soil to be solidified, S AI is the activity index of the soil binder solidified soil, and P1 is the first variable.

[0023] As an improvement of the above technical solution, the second relational expression is as follows:

[0024]

[0025] Among them, y is the total number of times of the stirring pile's downward penetration and upward lifting, x is the total number of times of slurry spraying during the downward penetration and upward lifting of the stirring pile, w t is the admixture content of the soil binder per meter in length, L is the slurry spraying flow rate, is the average speed of the downward penetration and upward lifting of the stirring pile, ρ is the density of the soil binder slurry, v w is the water consumption per meter in length, N is the number of stirring times at any point in the soil within the reinforcement range, and P2 is the second variable.

[0026] As an improvement of the above technical solution, the third relational expression is as follows:

[0027] P3 = alnt + b

[0028] Among them, a and b are obtained by fitting the unconfined compressive strength of the solidified soil specimens with the curing ages of the 3rd, 7th, 14th, and 28th days, t is the curing age, and P3 is the third variable.

[0029] As an improvement of the above technical solution, the prediction model is as follows:

[0030]

[0031] Among them, P1 is the first variable, P2 is the second variable, P3 is the third variable, h w is the natural moisture content of the silt to be solidified.

[0032] As an improvement of the above technical solution, judging the pile-forming effect of the soil binder stirring pile for the alluvial and deposited foundation soil according to the constructed prediction model includes:

[0033] If P > 0.9, the stirring pile is the first type of stirring pile, and the first type of stirring pile includes the stirring pile with a long-columnar core sample;

[0034] If 0.7 < P ≤ 0.9, the stirring pile is the second type of stirring pile, and the second type of stirring pile includes the stirring pile with a long-columnar core sample and the stirring pile with a short-columnar core sample, and the number of the stirring piles with a long-columnar core sample is greater than or equal to the number of the stirring piles with a short-columnar core sample;

[0035] If 0.5 < P ≤ 0.7, the stirring pile is the third type of stirring pile, and the third type of stirring pile includes the stirring pile with a long-columnar core sample and the stirring pile with a short-columnar core sample, and the number of the stirring piles with a long-columnar core sample is less than the number of the stirring piles with a short-columnar core sample;

[0036] If 0 ≤ P ≤ 0.5, the stirring pile is the fourth type of stirring pile, and the fourth type of stirring pile includes the non-formed stirring pile and the deformed stirring pile.

[0037] As an improvement of the above technical solution, the soil binder comprises the following raw materials by weight: 40 to 45 parts of ceramic powder, 5 to 10 parts of aluminum slag powder, 20 to 30 parts of calcined textile printing and dyeing sludge, 10 to 20 parts of calcined papermaking green sludge, and 10 to 20 parts of lithium slag;

[0038] The calcined textile printing and dyeing sludge is obtained by calcining textile printing and dyeing sludge, and the calcined papermaking green sludge is obtained by calcining papermaking green sludge. Among them, in the chemical components of the textile printing and dyeing sludge and the papermaking green sludge, the mass ratio of CaO to Na2O is (4 to 5):(5 to 6).

[0039] As an improvement of the above technical solution, the textile printing and dyeing sludge comprises the following chemical components by mass percentage: 53% to 60% of CaO + Na2O, 1% to 4% of SiO2, 1% to 2% of Al2O3, 5% to 8% of Fe2O3, 1% to 2% of MgO, and 25% to 35% of LOI;

[0040] As an improvement of the above technical solution, the papermaking green sludge comprises the following chemical components by mass percentage: 50% to 60% of CaO + Na2O, 5% to 7% of SiO2, 1% to 2% of Al2O3, 4% to 8% of Fe2O3, and 28% to 37% of LOI.

[0041] Implementing the present invention has the following beneficial effects:

[0042] The method for predicting the pile forming effect of the soil binder mixing pile of the present invention comprehensively considers the cementing effect of the soil binder, the construction parameters of the mixing pile, and the influence of the pile forming age on the pile forming effect of the soil binder mixing pile in the alluvial and silty foundation. Among them, considering the property differences between different silt soils in the alluvial and silty foundation, and aiming at the differences in the influence of the clay content and organic matter content of different silt soils on the strength of the solidified soil, an evaluation index of the activity index of the binder solidified soil and the clay content and organic matter content is established; the pile forming effect of the soil binder mixing pile in the alluvial and silty foundation is quantitatively analyzed through the prediction formula, and the pile forming effect under the change of the key construction parameters of the mixing pile is effectively predicted, reducing the error caused by the subjective qualitative description of the construction personnel. This prediction method can realize the prediction of the pile forming effect of the soil binder mixing pile in the alluvial and silty foundation only through a small number of indoor tests, reducing the consumption of human and material resources and improving the engineering efficiency. Description of the Drawings

[0043] Figure 1 is a schematic flow chart of the method for predicting the pile forming effect of the soil binder mixing pile in the alluvial and silty foundation provided by the present invention;

[0044] Figure 2 is a schematic diagram of the core sample of the mixing pile provided in Embodiment 1 of the present invention;

[0045] Figure 3 It is a schematic diagram of the core sample of the mixing pile provided in Embodiment 2 of the present invention;

[0046] Figure 4 It is a schematic diagram of the core sample of the mixing pile provided in Embodiment 3 of the present invention. Specific Embodiments

[0047] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below.

[0048] As Figure 1 shown, the present invention provides a method for predicting the forming effect of a soil binder mixing pile for alluvial and deposited foundation soil, including the following steps:

[0049] S1. Take samples of the soil to be solidified and determine the basic properties of the soil to be solidified.

[0050] Specifically, samples of the soil to be reinforced are taken during the engineering investigation stage. After sampling, they are immediately sealed in polyethylene bags and transported to the laboratory to determine the basic properties of the soil to be solidified. The basic properties of the soil to be solidified include the natural water content h w , clay content h c , and organic matter content h org .

[0051] Among them, the determination of the natural water content, clay content and organic matter content refers to JTG 3430-2020 "Highway Geotechnical Test Procedures".

[0052] S2. Prepare the soil binder, mix it with the soil to be solidified, and make a plurality of solidified soil specimens.

[0053] Specifically, the soil binder includes the following components by weight: 40 parts to 45 parts of ceramic powder, 5 parts to 10 parts of aluminum slag powder, 20 parts to 30 parts of calcined textile printing and dyeing sludge, 10 parts to 20 parts of calcined paper mill green mud, and 10 parts to 20 parts of lithium slag;

[0054] Among them, the calcined textile printing and dyeing sludge is obtained by calcining the sludge filtered from the wastewater in the processes of spinning, dyeing, and weaving. Textile printing and dyeing sludge often contains dyes, sizing agents, auxiliaries, etc., and has a relatively complex composition. The structure of the dyes contains nitro and amino compounds as well as heavy metal elements such as copper, chromium, zinc, and arsenic, which have great biological toxicity and cause relatively large pollution to the environment. If the textile printing and dyeing sludge is directly used as one of the raw materials for soil binders, it may cause serious secondary pollution to the environment due to the large amount of harmful microorganisms, viruses, and other organic pollutants contained in the textile printing and dyeing sludge. The main component of the calcined textile printing and dyeing sludge is metal oxide, and some of the metal oxides can react with the free water in the soil to generate alkaline substances, adjust the soil pH value, and promote the gelling reaction process. In one embodiment, by mass percentage, the textile printing and dyeing sludge includes the following chemical components: CaO + Na2O 53% - 60%, SiO2 1% - 4%, Al2O3 1% - 2%, Fe2O3 5% - 8%, MgO 1% - 2%, LOI 25% - 35%. The particle size of the calcined textile printing and dyeing sludge is ≤75μm, and the fine calcined textile printing and dyeing sludge can assist in improving the soil strength. Schematically, the addition amount of the calcined textile printing and dyeing sludge is 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, but not limited thereto. Preferably, the addition amount of the calcined textile printing and dyeing sludge is 22 parts - 28 parts.

[0055] Among them, the calcined papermaking green mud is obtained by calcining the substance separated from the green liquor in the causticizing section of the alkali recovery in the pulp and paper mill. The main component of the papermaking green mud is CaCO3. If the papermaking green mud is directly used as the raw material for soil binders, when it is mixed with soft soil later, a large amount of CaCO3 will cause too long setting time and have an adverse effect on the strength of the solidified soil body. The main component of the calcined papermaking green mud is metal oxide, and some of the metal oxides can react with the free water in the soil to generate alkaline substances, adjust the soil pH value, and promote the gelling reaction process. In one embodiment, by mass percentage, the papermaking green mud includes the following chemical components: CaO + Na2O 50% - 60%, SiO2 5% - 7%, Al2O3 1% - 2%, Fe2O3 4% - 8%, LOI 28% - 37%. The particle size of the calcined papermaking green mud is ≤75μm, and the fine papermaking green mud can assist in improving the soil strength. Schematically, the addition amount of the calcined papermaking green mud is 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, but not limited thereto. Preferably, the addition amount of the calcined papermaking green mud is 12 parts - 18 parts.

[0056] In one embodiment, when the textile printing and dyeing sludge is calcined, the calcination temperature is 550°C to 1000°C; when the papermaking green sludge is calcined, the calcination temperature is 800°C to 900°C. Under the above calcination conditions, the organic substances in the textile printing and dyeing sludge can be removed to prevent the solidified soil body from rotting and emitting odors, and the high temperature sterilizes and disinfects the textile printing and dyeing sludge, reducing the occurrence of pollution. And the papermaking green sludge is calcined to obtain calcined papermaking green sludge, which can remove the fine fibers, harmful microorganisms, viruses and other organic pollutants in the papermaking green sludge, reducing the occurrence of pollution. Moreover, the calcination treatment can remove CaCO3 in the papermaking green sludge, and CaCO3 decomposes during the above calcination process, thereby reducing the problem of too long setting time caused by the large amount of CaCO3 in the papermaking green sludge and alleviating the adverse impact on the strength of the solidified soil body due to the large amount of CaCO3 in the papermaking green sludge.

[0057] It should be noted that in the chemical compositions of the textile printing and dyeing sludge and the papermaking green sludge, the mass ratio of CaO to Na2O will affect the final soft soil solidification effect. If the content of CaO is too high, Ca(OH)2 is likely to seep out in the solidified soil, and Ca(OH)2 reacts with carbon dioxide in the air to form calcium carbonate, which is likely to cause phenomena such as surface peeling, chipping and even cracking of the solidified soil block; if the content of Na2O is too high, the content of soluble salts will increase. When the soluble salts recrystallize with the evaporation of water, they will carry a certain amount of crystal water, causing the volume to increase and generating an expansion phenomenon, resulting in a large expansion stress in the pores of the solidified soil and reducing the strength of the solidified soil body. In a preferred embodiment, in the chemical compositions of the textile printing and dyeing sludge and the papermaking green sludge, the mass ratio of CaO to Na2O is (4 - 5):(5 - 6).

[0058] Among them, the ceramic powder is the waste powder of sanitary ceramics or building ceramics. The powder residue is fine and has high pozzolanic activity. It can react with calcium hydroxide to form products such as calcium silicate hydrate and calcium aluminate hydrate, cementing soil particles and improving the strength of the soil body. In one embodiment, the particle size of the ceramic powder ≤ 75μm. Preferably, the particle size of the ceramic powder is 20μm - 30μm. The physical filling effect of the ceramic powder can fill the pores and improve the soil density. By mass percentage, the ceramic powder includes the following chemical components: CaO 1% - 5%, SiO2 12% - 21%, Al2O3 60% - 75%, Fe2O3 1% - 3%, Na2O 1% - 5%, MgO 1% - 5%, LOI 1% - 5%. Schematically, the addition amount of the ceramic powder is 42 parts, 43 parts, 44 parts, but not limited thereto. Preferably, the addition amount of the ceramic powder is 41.5 parts - 44.5 parts.

[0059] Among them, the aluminum slag powder is the waste residue produced in the production of aluminum profiles. Its main active component is Al2O3, and the physical filling effect of the aluminum slag powder can fill the pores and improve the soil density. By mass percentage, the aluminum slag powder includes the following chemical components: CaO 1% - 2%, SiO2 4% - 8%, Al2O3 70% - 84%, Fe2O3 2% - 5%, MgO 8% - 15%, LOI 0.1% - 1%. The particle size of the aluminum slag powder is ≤75μm; preferably, the particle size of the aluminum slag powder is 60μm - 70μm, and the physical filling effect of the aluminum slag powder can fill the pores and improve the soil density. Schematically, the addition amount of the aluminum slag powder is 6 parts, 7 parts, 8 parts, 9 parts, but not limited thereto. Preferably, the addition amount of the aluminum slag powder is 5.5 parts - 9.5 parts.

[0060] Among them, the lithium slag is the solid waste produced after extracting lithium carbonate by the sulfuric acid method. The main phase is amorphous aluminosilicate phase, which has pozzolanic activity. The contained sulfate can react with calcium aluminate hydrate to generate ettringite with swelling characteristics, thereby filling high-porosity soft soil and improving the curing strength. By mass percentage, the lithium slag includes the following chemical components: CaO 4% - 5%, SiO2 50% - 60%, Al2O3 18% - 25%, Fe2O3 0.1% - 1.5%, SO3 8% - 15%, LOI 8% - 12%. Schematically, the addition amount of the lithium slag is 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, but not limited thereto. Preferably, the addition amount of the lithium slag is 12 parts - 18 parts.

[0061] In one embodiment, the particle size of the lithium slag is ≤15μm. Preferably, the lithium slag is ground, and the specific surface area of the lithium slag is controlled at ≥400m 2 / kg through the grinding process. Grinding makes the grain size of the lithium slag particles smaller and the structure disordered, and an amorphous aluminosilicate phase is formed on the surface. The reaction activity of the lithium slag can be improved through physical grinding, and the micro-aggregate effect can be better exerted. Preferably, the particle size of the lithium slag is 1μm - 10μm.

[0062] In one embodiment, the preparation method of the soil binder is as follows: by weight, 40 parts - 45 parts of ceramic powder, 5 parts - 10 parts of aluminum slag powder, 20 parts - 30 parts of calcined textile printing and dyeing sludge, 10 parts - 20 parts of calcined paper green mud and 10 parts - 20 parts of lithium slag are mixed to obtain the finished product. The forming method of the solidified soil specimen refers to JGJ / T233 - 2011 "Code for Design of Cement Soil Mix Proportion".

[0063] S3. Measure the unconfined compressive strength of the solidified soil specimen and the activity index of the soil binder solidified soil.

[0064] The characterization method of the activity index of soil binder solidified soil is a modified method based on GB / T 17671-2021 "Test Method for the Strength of Cement Mortar (ISO Method)". The cement-sand system in this standard cannot fully characterize the gelling and filling ability of the binder in soft soil. This is mainly because the pore size of cement mortar mainly concentrates in the range of 20nm - 200nm, while cement solidified soil has a loose structure with a large number of pores, and the pore size distribution is in the range of 300nm - 1000nm. The expansive substances generated by the hydration of soil binder can effectively fill the large pores in the solidified soil and improve the soil density, while these expansive substances will damage the internal structure of cement mortar and reduce the macroscopic strength.

[0065] Specifically, the characterization method of the activity index of soil binder solidified soil is as follows: Measure the unconfined compressive strength at 28 days of the solidified soil specimen and the control cement solidified soil specimen, and determine the activity index of soil binder solidified soil based on the ratio of the unconfined compressive strengths of the two, that is, the activity index of soil binder solidified soil = (unconfined compressive strength at 28 days of the solidified soil specimen / unconfined compressive strength at 28 days of the control cement solidified soil specimen) × 100%. Among them, the dosages and water-binder ratios of the solidified soil specimen and the control cement solidified soil specimen are the same, that is, except for using soil binder and cement respectively for the solidification of silt soil, the other conditions are the same.

[0066] Among them, the test method for the unconfined compressive strength of the solidified soil specimen and the control cement solidified soil specimen refers to JGJ / T233-2011 "Design Code for Cement Soil Mix Proportion".

[0067] The soil binder used for the control cement solidified soil specimen is PO42.5 cement, which is ordinary Portland cement, and its basic properties are shown in Table 1.

[0068] Table 1 Physical Properties of Cement for Tests

[0069]

[0070] S4. Determine the construction parameters of the mixing pile.

[0071] Specifically, the construction parameters of the mixing pile include the total number of times y of the mixing pile's downward penetration and upward lifting, the total number of times x of slurry spraying during the mixing pile's downward penetration and upward lifting, the dosage w of soil binder per linear meter t , the slurry spraying flow rate L, the average speed v of the mixing pile's downward penetration and upward lifting, the density ρ of the soil binder slurry, the water consumption v per linear meter w , and the number of mixing times N at any point in the soil within the reinforcement range.

[0072] Among them, the test method for the density of the soil binder slurry refers to GB / T 19139-2012 "Test Methods for Oil Well Cement". The stirring times N at any point in the soil within the reinforcement range are calculated with reference to GB / T 50783-2012 "Technical Code for Composite Foundations" as follows:

[0073]

[0074] Among them, h = the width of the stirring blade (m);

[0075] β = the vertical angle between the stirring blade and the stirring shaft (°);

[0076] Z = the total number of stirring blades;

[0077] V = the lifting speed of the stirring head (m / min);

[0078] n = the rotation speed of the stirring head (r / min).

[0079] S5. Construct a prediction model for the pile-forming effect of the soil binder mixing pile.

[0080] Specifically, the construction method of the prediction model is as follows:

[0081] S51. Establish a first relational expression for the first variable.

[0082] Specifically, the first relational expression is as follows:

[0083] P1 = S AI -(h c +h org )

[0084] Among them, h c is the clay content of the soft soil to be solidified, h org is the organic matter content of the soft soil to be solidified, S AI is the activity index of the soil binder solidified soil, and P1 is the first variable.

[0085] S52. Establish a second relational expression for the second variable.

[0086] Specifically, the second relational expression is as follows:

[0087]

[0088] Among them, y is the total number of times of stirring during the downward penetration and upward lifting of the mixing pile, x is the total number of times of spraying slurry during the downward penetration and upward lifting of the mixing pile, w t is the soil binder dosage per linear meter, L is the spraying slurry flow rate, is the average speed of the downward penetration and upward lifting of the mixing pile, ρ is the density of the soil binder slurry, v wW is the water consumption per meter, N is the number of mixing times at any point in the soil within the reinforcement range, and P2 is the second variable.

[0089] S53. Establish a third relationship regarding the third variable based on the unconfined compressive strength of the solidified soil specimens.

[0090] Specifically, the third relationship is as follows:

[0091] P3 = alnt + b

[0092] Wherein, a and b are obtained by fitting the unconfined compressive strength values of the solidified soil specimens at the 3rd, 7th, 14th, and 28th days of the pile-forming age, t is the pile-forming age, and P3 is the third variable.

[0093] S54. Construct a prediction model for the pile-forming effect of the soil binder mixing pile according to the weights of the first variable, the second variable, and the third variable and the natural water content of the silt to be solidified.

[0094] Specifically, the prediction model is as follows:

[0095]

[0096] Wherein, P1 is the first variable, P2 is the second variable, P3 is the third variable, and h w is the natural water content of the silt to be solidified.

[0097] S6. Judge the pile-forming effect of the soil binder mixing pile according to the constructed prediction model for the pile-forming effect of the soil binder mixing pile.

[0098] Specifically, according to the value calculated by the prediction model for the pile-forming effect of the soil binder mixing pile, refer to Table 2 to predict the pile-forming effect of the soil binder mixing pile for the alluvial and deposited foundation soil.

[0099] Table 2 Pile-forming effect prediction table

[0100]

[0101]

[0102] It can be understood that the hardness, relatively hard, and plastic state of the core sample can be judged by the degree of finger pressing. Specifically, no mark after pressing is hard, a slight indentation after pressing is relatively hard, and it is easy to knead into a ball is plastic.

[0103] The following further illustrates the present invention with specific embodiments:

[0104] Embodiment 1

[0105] This embodiment provides a method for predicting the pile-forming effect of a soil binder mixing pile for an alluvial and deposited foundation soil, including the following steps;

[0106] S1. Take samples of the to-be-solidified silt and measure the basic properties of the to-be-solidified silt.

[0107] In this embodiment, the soil samples are taken from a certain mixing pile test section on Tangxi Avenue, Sanshui District, Foshan City, and the excavation depth is 4m to 15m. The basic performance indexes of the soil samples are shown in Table 3.

[0108] Table 3 Basic properties of soil samples

[0109]

[0110] S2. Prepare a soil binder, mix it with the to-be-solidified silt, and make a plurality of solidified soil specimens.

[0111] The soil binder used in this embodiment includes the following components by weight: 45 parts of ceramic powder, 5 parts of aluminum slag powder, 20 parts of calcined textile printing and dyeing sludge, 10 parts of calcined papermaking green mud, and 20 parts of lithium slag;

[0112] The calcined textile printing and dyeing sludge is obtained by calcining textile printing and dyeing sludge at 900°C, and the calcined papermaking green mud is obtained by calcining papermaking green mud at 900°C;

[0113] Among them, the chemical composition of the ceramic powder is:

[0114] CaO 1.79wt%, Al2O3 74.49wt%, SiO2 12.61wt%, Fe2O3 2.12wt%, Na2O 2.85wt%, MgO 3.47wt%, LOI 2.67wt%.

[0115] The chemical composition of the aluminum slag powder is:

[0116] CaO 1.64wt%, SiO2 4.89wt%, Al2O3 79.95wt%, Fe2O3 3.56wt%, MgO 9.28wt%, LOI 0.68wt%.

[0117] The chemical composition of the textile printing and dyeing sludge is:

[0118] CaO + Na2O 53.46wt%, SiO2 3.19wt%, Al2O3 1.25%, Fe2O3 6.23wt%, MgO 1.49wt%, LOI 34.38wt%.

[0119] The chemical composition of the papermaking green mud is:

[0120] CaO + Na2O 53.38wt%, SiO2 5.49wt%, Al2O3 1.64wt%, Fe2O3 5.54wt%, LOI 33.95wt%.

[0121] In the chemical compositions of textile printing and dyeing sludge and papermaking green sludge, the mass ratio of CaO to Na2O is 4:6.

[0122] The chemical composition of lithium slag is as follows:

[0123] CaO 4.63wt%, SiO2 52.21wt%, Al2O3 20.61%, Fe2O3 0.84wt%, SO3 9.81wt%, LOI 11.90wt%.

[0124] The dosage of soil binder is 17% of the dry soil mass, and the water-binder ratio is 0.7.

[0125] S3. Measure the unconfined compressive strength of the solidified soil specimens and the activity index of the soil binder solidified soil, as shown in Table 4 specifically.

[0126] Table 4 Unconfined Compressive Strength (MPa) and Activity Index of Solidified Soil

[0127]

[0128] S4. Determine the construction parameters of the mixing pile. Specifically, the construction parameters of the mixing pile are shown in Table 5.

[0129] Table 5 Construction Parameters of Mixing Pile

[0130]

[0131] S5. Construct a prediction model for the pile-forming effect of the soil binder mixing pile. Specifically, it includes the following steps:

[0132] S51. Establish a first relationship about the first variable, specifically as follows:

[0133] P1 = S AI -(h c +h org )

[0134] where h c is the clay content of the sludge to be solidified, h org is the organic matter content of the sludge to be solidified, S AI is the activity index of the soil binder solidified soil, and P1 is the first variable.

[0135] S52. Establish a second relationship about the second variable, specifically as follows:

[0136]

[0137] where y is the total number of times of mixing during the downward penetration and upward lifting of the mixing pile, x is the total number of times of slurry spraying during the downward penetration and upward lifting of the mixing pile, w tis the soil binder dosage per meter, L is the spraying flow rate, is the average speed of the mixing pile's downward penetration and upward lifting, ρ is the density of the soil binder slurry, v w is the water consumption per meter, N is the number of mixing times at any point in the soil within the reinforcement range, and P2 is the second variable.

[0138] S53. Based on the unconfined compressive strength of the solidified soil specimens, establish the third relationship regarding the third variable, specifically as follows:

[0139] P3 = alnt + b

[0140] where a and b are obtained by fitting the unconfined compressive strength of the solidified soil specimens with curing ages of 3, 7, 14, and 28 days, t is the curing age, and P3 is the third variable.

[0141] Among them, according to the unconfined compressive strength of the solidified soil at 3, 7, 14, and 28 days, the fitting curve is obtained, as shown in Table 6 specifically.

[0142] Table 6 Fitting Table of Unconfined Compressive Strength of Solidified Soil

[0143] Number Fitting curve Fitting degree TX-1 0.563(lnt)-0.202 0.9991 TX-2 0.613(lnt)-0.232 0.9964 TX-3 0.553(lnt)-0.250 0.9921 TX-4 0.487(lnt)-0.191 0.9984 TX-5 0.330(lnt)-0.074 0.9991

[0144] S54. According to the weights of the first variable, the second variable, and the third variable and the natural moisture content of the silt soil to be solidified, construct a prediction model for the pile-forming effect of the soil binder mixing pile in the alluvial-proluvial foundation soil, specifically as follows:

[0145]

[0146] where P1 is the first variable, P2 is the second variable, P3 is the third variable, and h w is the natural moisture content of the silt soil to be solidified.

[0147] S6. Judge the pile-forming effect of the soil binder mixing pile according to the constructed prediction model for the pile-forming effect of the soil binder mixing pile, as shown in Table 7 specifically.

[0148] Table 7 Prediction Table of Pile-Forming Effect

[0149]

[0150] Example 2

[0151] This example provides a prediction method for the pile-forming effect of the soil binder mixing pile in the alluvial-proluvial foundation soil, including the following steps;

[0152] S1. Take samples of the silt soil to be solidified and measure the basic properties of the silt soil to be solidified.

[0153] In this embodiment, the soil samples are taken from a certain mixing pile test section of Tanzhou Avenue in Zhongshan City, and the excavation depth is 2m to 15m. The basic performance indexes of the soil samples are shown in Table 8.

[0154] Table 8 Basic Performance of Soil Samples

[0155]

[0156] S2. Prepare the soil binder, mix it with the soft soil to be solidified, and make multiple solidified soil specimens.

[0157] The soil binder used in this embodiment is different from that in Embodiment 1 in that it includes the following components by weight: 40 parts of ceramic powder, 10 parts of aluminum slag powder, 30 parts of calcined textile printing and dyeing sludge, 10 parts of calcined paper-making green mud, and 10 parts of lithium slag. The rest are the same as those in Embodiment 1.

[0158] S3. Measure the unconfined compressive strength of the solidified soil specimens and the activity index of the soil binder solidified soil, as specifically shown in Table 9.

[0159] Table 9 Unconfined Compressive Strength (MPa) and Activity Index of Solidified Soil

[0160]

[0161] S4. Determine the construction parameters of the mixing pile. Specifically, the construction parameters of the mixing pile are shown in Table 10.

[0162] Table 10 Construction Parameters of Mixing Pile

[0163]

[0164] S5. Build a prediction model for the pile-forming effect of the soil binder mixing pile. Specifically, it includes the following steps:

[0165] S51. Establish a first relationship about the first variable, specifically as follows:

[0166] P1 = S AI -(h c + h org )

[0167] Where h c is the clay content of the soft soil to be solidified, h org is the organic matter content of the soft soil to be solidified, S AI is the activity index of the soil binder solidified soil, and P1 is the first variable.

[0168] S52. Establish a second relationship about the second variable, specifically as follows:

[0169]

[0170] Among them, y is the total number of times of the mixing pile's downward penetration and upward lifting, x is the total number of times of slurry spraying during the downward penetration and upward lifting of the mixing pile, w t is the admixture content of the soil binder per meter in length, L is the slurry spraying flow rate, is the average speed of the downward penetration and upward lifting of the mixing pile, ρ is the density of the soil binder slurry, v w is the water consumption per meter in length, N is the number of mixing times at any point in the soil within the reinforcement range, and P2 is the second variable.

[0171] S53. Establish a third relationship regarding the third variable based on the unconfined compressive strength of the solidified soil specimens, as follows:

[0172] P3 = alnt + b

[0173] Among them, a and b are obtained by fitting the unconfined compressive strength of the soil solidified soil specimens at the 3rd, 7th, 14th, and 28th days of the pile formation age, t is the pile formation age, and P3 is the third variable.

[0174] Among them, according to the unconfined compressive strength of the solidified soil at 3, 7, 14, and 28 days, a fitting curve is obtained, as shown in Table 11 specifically.

[0175] Table 11 Fitting Table of Unconfined Compressive Strength of Solidified Soil

[0176] Number Fitting curve Fitting degree TZ-1 0.645(lnt)-0.253 0.9989 TZ-2 0.633(lnt)-0.260 0.9993 TZ-3 0.533(lnt)-0.170 0.9998 TZ-4 0.245(lnt)+0.009 0.9970 TZ-5 0.205(lnt)+0.053 0.9942

[0177] S54. Construct a prediction model for the pile formation effect of the soil binder mixing pile in the alluvial and deposited foundation soil according to the weights of the first variable, the second variable, and the third variable and the natural water content of the silt to be solidified, as follows:

[0178]

[0179] Among them, P1 is the first variable, P2 is the second variable, P3 is the third variable, h w is the natural water content of the silt to be solidified.

[0180] S6. Judge the pile formation effect of the soil binder mixing pile according to the constructed prediction model for the pile formation effect of the soil binder mixing pile, as shown in Table 12 specifically.

[0181] Table 12 Prediction Table of Pile Formation Effect

[0182]

[0183]

[0184] Example 3

[0185] This example provides a prediction method for the pile formation effect of the soil binder mixing pile in the alluvial and deposited foundation soil, including the following steps;

[0186] S1. Take samples of the soil to be solidified and determine the basic properties of the soil to be solidified.

[0187] In this embodiment, the soil samples are taken from the mixing pile test section of the Longxiang Bridge and its approach project in Foshan City, and the excavation depth is 1 m to 10 m. The basic performance indexes of the soil samples are shown in Table 13.

[0188] Table 13 Basic properties of soil samples

[0189]

[0190] S2. Prepare a soil binder, mix it with the soil to be solidified, and make a plurality of solidified soil specimens.

[0191] The difference between the soil binder used in this embodiment and that in Embodiment 1 is that the chemical composition of the textile printing and dyeing sludge is:

[0192] CaO + Na2O 58.76 wt%, SiO2 2.43 wt%, Al2O3 1.3%, Fe2O3 7.59 wt%, MgO 1.12 wt%, LOI 28.8 wt%.

[0193] The chemical composition of the papermaking green mud is:

[0194] CaO + Na2O 54.78 wt%, SiO2 6.23 wt%, Al2O3 1.75 wt%, Fe2O3 4.12 wt%, LOI 33.12 wt%.

[0195] In the chemical compositions of the textile printing and dyeing sludge and the papermaking green mud, the mass ratio of CaO to Na2O is 5:5. The rest are the same as those in Embodiment 1.

[0196] S3. Determine the unconfined compressive strength of the solidified soil specimens and the curing activity index of the soil binder. Specifically, it is shown in Table 14.

[0197] Table 14 Unconfined compressive strength (MPa) and activity index of solidified soil

[0198]

[0199] S4. Determine the construction parameters of the mixing pile. Specifically, the construction parameters of the mixing pile are shown in Table 15.

[0200] Table 15 Construction parameters of mixing pile

[0201]

[0202] S5. Build a prediction model for the pile forming effect of the soil binder mixing pile. Specifically, it includes the following steps:

[0203] S51. Establish the first relationship about the first variable as follows:

[0204] P1 = S AI -(h c + h org )

[0205] where h c is the clay content of the soft soil to be solidified, h org is the organic matter content of the soft soil to be solidified, S AI is the activity index of soil binder solidified soil, and P1 is the first variable.

[0206] S52. Establish the second relationship about the second variable as follows:

[0207]

[0208] where y is the total number of times of the mixing pile's downward penetration and upward lifting for mixing, x is the total number of times of slurry spraying during the downward penetration and upward lifting of the mixing pile, w t is the soil binder dosage per meter in length, L is the slurry spraying flow rate, is the average speed of the mixing pile's downward penetration and upward lifting, ρ is the density of the soil binder slurry, v w is the water consumption per meter in length, N is the number of times of mixing at any point in the soil mass within the reinforcement range, and P2 is the second variable.

[0209] S53. Establish the third relationship about the third variable according to the unconfined compressive strength of the solidified soil specimen as follows:

[0210] P3 = alnt + b

[0211] where a and b are obtained by fitting the unconfined compressive strength of the solidified soil specimens at the 3rd, 7th, 14th, and 28th days of the pile formation age, t is the pile formation age, and P3 is the third variable.

[0212] Among them, according to the unconfined compressive strength of the solidified soil at 3, 7, 14, and 28 days, the fitting curve is obtained, as shown in Table 16 specifically.

[0213] Table 16 Fitting Table of Unconfined Compressive Strength of Solidified Soil

[0214] Number Fitting curve Fitting degree LX-1 0.512(lnt)-0.052 0.9853 LX-2 0.513(lnt)-0.113 0.9899 LX-3 0.521(lnt)-0.175 0.9696 LX-4 0.557(lnt)-0.191 0.9914 LX-5 0.443(lnt)-0.268 0.9674

[0215] S54. Construct a prediction model for the pile formation effect of the soil binder mixing pile in the alluvial foundation according to the weights of the first variable, the second variable, and the third variable and the natural water content of the soft soil to be solidified as follows:

[0216]

[0217] Among them, P1 is the first variable, P2 is the second variable, P3 is the third variable, and h w is the natural water content of the silt to be solidified.

[0218] S6. Judge the pile-forming effect of the soil binder mixing pile according to the established pile-forming effect prediction model of the soil binder mixing pile, as shown in Table 17 specifically.

[0219] Table 17 Pile-forming effect prediction table

[0220]

[0221] As can be seen from Table 7, Table 12 and Table 17, the prediction method provided by the present invention comprehensively considers the cementing effect of the soil binder, the mixing pile process parameters, and the influence of the pile-forming age on the pile-forming effect of the soil binder mixing pile, and realizes the effective prediction of the pile-forming effect of the soil binder mixing pile with different depths and different soil types. This prediction method quantitatively analyzes the pile-forming effect of the soil binder mixing pile, effectively predicts the pile-forming effect under the changes of the cementing effect of the soil binder, the key construction parameters of the mixing pile, and the pile-forming age, reduces the error caused by the subjective qualitative description of the construction personnel, and only needs a small number of indoor tests (5-8 groups) to realize the prediction of the pile-forming effect of the soil binder mixing pile for the alluvial silty clay foundation soil, reduces the consumption of human and material resources, and improves the engineering efficiency.

[0222] The above is the preferred implementation manner of the invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A prediction method for the forming effect of a mixing pile of a scouring and silting facies foundation soil binder, characterized in that, It includes the following steps: Sampling the soft soil to be solidified and determining the basic properties of the soft soil to be solidified; Preparing a soil binder, mixing it with the soft soil to be solidified, and making a plurality of solidified soil specimens; Determining the unconfined compressive strength of the solidified soil specimens and the soil binder solidified soil activity index; Determining the construction parameters of the mixing pile; Constructing a prediction model for the pile-forming effect of the soil binder mixing pile in the alluvial foundation soil; Judging the pile-forming effect of the soil binder mixing pile in the alluvial foundation soil according to the constructed prediction model.

2. The prediction method for the pile forming effect of the mixing pile of the alluvial and sedimentary foundation soil binder as described in claim 1, characterized in that, The basic properties of the soft soil to be solidified include the natural water content h w , clay content h c , organic matter content h org ; The construction parameters of the mixing pile include the total number of times y of downward penetration and upward lifting of the mixing pile, the total number of times x of slurry spraying during downward penetration and upward lifting of the mixing pile, the admixture amount w of soil binder per linear meter t , the slurry spraying flow rate L, the average speed v of downward penetration and upward lifting of the mixing pile, the density ρ of the soil binder slurry, the water consumption v per linear meter w , the number of mixing times N at any point in the soil within the reinforcement range.

3. The prediction method for the pile forming effect of the cementing material mixing pile in the alluvial and sedimentary foundation soil as described in claim 1, characterized in that, The constructing of the prediction model for the pile-forming effect of the soil binder mixing pile in the alluvial foundation soil includes: Establishing a first relational expression for the first variable; Establishing a second relational expression for the second variable; Establishing a third relational expression for the third variable according to the unconfined compressive strength of the solidified soil specimens; Constructing a prediction model for the pile-forming effect of the soil binder mixing pile in the alluvial foundation soil according to the weights of the first variable, the second variable and the third variable and the natural water content of the soft soil to be solidified.

4. The prediction method for the pile forming effect of the siltation and alluviation phase foundation soil binder mixing pile according to claim 3, characterized in that, The first relational expression is as follows: P1 = S AI -(h c +h org ) where h c is the clay content of the soft soil to be solidified, and h org is the organic matter content of the soft soil to be solidified, S AI is the activity index of the soil binder solidified soil, and P1 is the first variable.

5. The prediction method for the pile-forming effect of the cemented soil mixing pile in the alluvial and silty foundation soil as described in claim 3, characterized in that, The second relational expression is as follows: Among them, y is the total number of times of the mixing pile's downward penetration and upward lifting for mixing, x is the total number of times of grout spraying during the downward penetration and upward lifting of the mixing pile for mixing, w t is the admixture content of the soil binder per meter in length, L is the grout spraying flow rate, is the average speed of the downward penetration and upward lifting of the mixing pile, ρ is the density of the soil binder slurry, v w is the water consumption per meter in length, N is the number of times of mixing at any point in the soil within the reinforcement range, and P2 is the second variable.

6. The prediction method for the pile forming effect of the siltation and deposition phase foundation soil binder mixing pile according to claim 3, characterized in that, The third relational expression is as follows: P3 = alnt + b Wherein, a and b are obtained by fitting the unconfined compressive strength of the solidified soil specimens at the 3rd, 7th, 14th, and 28th days of the pile-forming age, t is the pile-forming age, and P3 is the third variable.

7. The prediction method for the pile forming effect of the cementing material mixing pile in alluvial foundation soil as described in claim 3, characterized in that The prediction model is as follows: Among them, P1 is the first variable, P2 is the second variable, P3 is the third variable, and h w is the natural water content of the soft soil to be solidified.

8. The prediction method for the pile forming effect of the cementitious material mixing pile in the alluvial-proluvial facies foundation soil as described in claim 3, wherein, Judging the pile-forming effect of the soil binder mixing pile in the alluvial foundation soil according to the constructed prediction model includes: If P > 0.9, the mixing pile is the first type of mixing pile, and the first type of mixing pile includes a mixing pile with a long-columnar core sample; If 0.7 < P ≤ 0.9, the mixing pile is the second type of mixing pile, and the second type of mixing pile includes a mixing pile with a long-columnar core sample and a mixing pile with a short-columnar core sample, and the number of mixing piles with a long-columnar core sample is greater than or equal to the number of mixing piles with a short-columnar core sample; If 0.5 < P ≤ 0.7, the mixing pile is the third type of mixing pile, and the third type of mixing pile includes a mixing pile with a long-columnar core sample and a mixing pile with a short-columnar core sample, and the number of mixing piles with a long-columnar core sample is less than the number of mixing piles with a short-columnar core sample; If 0 ≤ P ≤ 0.5, the mixing pile is the fourth type of mixing pile, and the fourth type of mixing pile includes an unformed mixing pile and a deformed mixing pile.

9. The prediction method for the pile forming effect of the siltation and deposition phase foundation soil binder mixing pile according to claim 1, characterized in that, The soil binder includes the following raw materials by weight: 40 to 45 parts of ceramic powder, 5 to 10 parts of aluminum slag powder, 20 to 30 parts of calcined textile printing and dyeing sludge, 10 to 20 parts of calcined paper-making green mud, and 10 to 20 parts of lithium slag; The calcined textile printing and dyeing sludge is obtained by calcining textile printing and dyeing sludge, and the calcined paper-making green mud is obtained by calcining paper-making green mud. Among them, in the chemical components of the textile printing and dyeing sludge and the paper-making green mud, the mass ratio of CaO to Na2O is (4 to 5):(5 to 6).

10. The prediction method for the pile forming effect of the siltation and alluvium foundation soil binder mixing pile as described in claim 9, characterized in that, The textile printing and dyeing sludge includes the following chemical components by mass percentage: CaO + Na2O 53% to 60%, SiO2 1% to 4%, Al2O3 1% to 2%, Fe2O3 5% to 8%, MgO 1% to 2%, LOI 25% to 35%; The papermaking green mud contains the following chemical components by mass percentage: CaO + Na2O 50% - 60%, SiO2 5% - 7%, Al2O3 1% - 2%, Fe2O3 4% - 8%, LOI 28% - 37%.

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