Flow state curing backfill material with controllable performance as well as design method and application of flow state curing backfill material

Abstract

The invention relates to a performance-controllable flow-state curing backfill material and a design method and application of the performance-controllable flow-state curing backfill material. Mutual influence among different doped materials in a multi-index regulation and control process is considered, and the performance-controllable flow-state curing backfill material is obtained through a single-variable experiment and a multi-variable experiment; and a prediction formula for the strength, fluidity, setting time and density of the flow-state solidified backfill soil under single variable and multivariable conditions is provided. The problem that indexes such as density and setting time cannot be effectively controlled at the same time through a traditional flow state solidification backfill material design method is solved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a fluid solidifying backfill material with controllable performance and a design method and application thereof. Background Art

[0002] In traditional backfill projects, the backfill material usually needs to be compacted. However, in projects such as backfilling of foundation pit fertilizer troughs, abandoned air defense holes, and abandoned mine pits, insufficient compaction often occurs, resulting in problems such as settlement and subsidence, affecting the normal use and life of the engineering structure. In addition, in many urban pipeline network construction and some narrow pipeline corridor construction projects, it is also difficult to use mechanical compaction, resulting in insufficient density of the backfill material.

[0003] The fluidized backfill technology is to pour the backfill material directly in the backfill project after fluidizing it. Under the action of its own gravity, the backfill material can achieve self-leveling and self-compacting. After a period of maintenance, under the action of the solidified material, the backfill material can form a certain strength. Compared with the traditional backfill treatment method, the fluidized backfill technology has the following advantages: absorbing waste, improving density, and solving the problem of compaction dead corners.

[0004] Fluidized solidified backfill material can be prepared using shield mud, construction mud or dredged sludge as raw materials. When used, it is usually necessary to adjust the density, fluidity, strength and setting time of the fluidized solidified backfill material according to different engineering requirements. The existing design methods of fluidized solidified backfill material usually only adjust one or two factors, which greatly limits the application of fluidized solidified backfill material. Summary of the invention

[0005] The first purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a design method for a fluidized solidifying backfill material with controllable performance. The design method of the present invention simultaneously considers the design of the fluidized solidifying backfill material under four indicators: density, fluidity, strength and setting time of the fluidized solidifying backfill material.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A design method for a fluid solidifying backfill material with controllable performance, comprising:

[0008] Water, curing agent, retarder and filler for density adjustment are used as filler control components, and initial moisture content, curing agent dosage, filler dosage and retarder dosage are used as control variables;

[0009] The single variable prediction formulas of fluidity and initial water content of fluidized solidified soil, strength and curing agent dosage of fluidized solidified soil, density and filler dosage of fluidized solidified soil, setting time and retarder dosage of fluidized solidified soil were constructed respectively.

[0010] According to the design values ​​of fluidity, strength, setting time and density, combined with the preset total mass of soil, the corresponding single variable prediction formula is used to obtain the initial water mass, curing agent mass, filling material mass and retarder mass;

[0011] Keeping the total mass of initial water, curing agent, filler and retarder, and the total mass of soil fixed, construct multivariate prediction formulas for fluidity, strength, setting time and at least three control variables of fluidized solidified soil;

[0012] According to the design values ​​of fluidity, strength, setting time and density, the optional ratio range of the control variables in each of the multivariable prediction formulas and the single variable prediction formula based on the density of the fluidized solidified soil and the filler dosage is determined, and the optional ratio ranges of the control variables determined by multiple multivariable prediction formulas are taken as the union to obtain the dosage ratio range of the filler control component.

[0013] As a preferred embodiment, the single variable prediction formula of the fluidity and initial water content of the fluidized solidified soil is in a linear form;

[0014] The single variable prediction formula for the strength of fluidized solidified soil and the amount of solidifying agent is in exponential form;

[0015] The single variable prediction formula for the setting time of fluidized solidified soil and the amount of retarder is in exponential form;

[0016] The single variable prediction formula for the density of fluidized solidified soil and the filler dosage is a calculation formula for the density of fluidized solidified soil established with the filler dosage as the independent variable and the soil material density and the filler density as fixed parameters.

[0017] As a preferred implementation, single-variable prediction formulas and multi-variable prediction formulas for fluidity, strength, setting time, density and variables are established based on fluidity tests, strength tests, setting time tests and density tests, respectively.

[0018] As a preferred implementation, the multivariable prediction formula is a multivariable prediction formula of fluidity, strength, setting time and three control variables of fluidized solidified soil.

[0019] Furthermore, the multivariate prediction formula includes:

[0020] Multivariable prediction formula for fluidity of fluidized solidified soil and initial water content, curing agent dosage and filler dosage;

[0021] Multivariate prediction formula for fluidized solidified soil strength and solidifying agent dosage, initial water content and filler dosage;

[0022] A multivariate prediction formula for the setting time of fluidized solidified soil and the initial moisture content, the dosage of solidifying agent and the dosage of retarder.

[0023] The multivariable prediction formula can be three-variable or four-variable. The four-variable prediction formula can more comprehensively consider the influence of various factors, but the omission of some non-essential factors can reduce the amount of experimental calculations. For example, the initial moisture content, fillers and curing agents have a greater impact on fluidity, but retarders mostly prolong the time that the mixture is in a fluid state and have little effect on fluidity. Therefore, a three-variable prediction formula can be used to establish a multivariable prediction formula; and except for fillers, the effects of other variables on density are opposite. Based on their usual usage, they can be considered to offset the effects on density. Therefore, a single-variable prediction formula can be directly used to consider the factors affecting density.

[0024] Furthermore, the multivariate prediction formula is in the following form:

[0025] The multivariate prediction formula of fluidity of fluidized solidified soil, initial water content, curing agent dosage and filler dosage is:

[0026]

[0027] Where:

[0028] The fluidity of the fluidized solidified soil; is the initial moisture content; is the curing agent dosage; is the filling amount; , , , , For fitting parameters, calibrated by experiment;

[0029] The multivariate prediction formula of fluidized solidified soil strength and solidifying agent dosage, initial water content and filler dosage is:

[0030]

[0031] Where:

[0032] It is the strength of fluidized solidified soil; is the initial moisture content; is the curing agent dosage; is the filling amount; , , , , For fitting parameters, calibrated by experiment;

[0033] The multivariate prediction formula of the setting time of fluidized solidified soil and the initial moisture content, the dosage of the solidifying agent and the dosage of the retarder is:

[0034]

[0035] Where:

[0036] It is the setting time of fluidized solidified soil; is the initial moisture content; is the retarder dosage; is the curing agent dosage; , , , , The fitting parameters are calibrated through experiments.

[0037] As a preferred implementation, a ternary diagram or a quaternary diagram is established for the obtained multivariate prediction formula, the optional ratio range of the variables determined in each ternary diagram or quaternary diagram is obtained, and the optional ratio range of the variables confirmed in all ternary diagrams or quaternary diagrams is taken as the union to obtain the dosage ratio range of the filler regulating component.

[0038] As a preferred embodiment, the filler is EPS particles, air bubbles or rubber particles.

[0039] The second object of the present invention is to provide a fluidized solidified backfill material with controllable performance obtained based on the above-mentioned design method.

[0040] The third object of the present invention is to provide application of the above-mentioned design method in fluidized backfill engineering.

[0041] Compared with the previous fluidized solidified backfill material design method, the present invention realizes the preparation of backfill material under controllable multiple indicators. The present invention takes into account the mutual influence between different admixture materials during the multi-indicator regulation process, and provides single variable and multivariate prediction formulas for the strength, fluidity, setting time and density of fluidized solidified backfill soil under single variable and multivariate experiments. This solves the problem that the traditional fluidized solidified backfill material design method cannot effectively control indicators such as density and setting time at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a ternary diagram of the change in fluidity in the multivariate experiment.

[0043] Figure 2 is a ternary plot of intensity variation in a multivariate experiment.

[0044] Figure 3 is a ternary plot of the variation of clotting time in a multivariate experiment. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0046] The soil material referred to in the present invention may be silt, construction waste, engineering mud and miscellaneous fill soil.

[0047] Example 1

[0048] The present invention proposes a design method for fluidized solidified backfill material, which can adjust the fluidity, strength, density and setting time of fluidized solidified backfill material by adjusting the initial moisture content of soil material, adding a solidifying agent, adding a filler and adding a retarder, and is used for corresponding single variable and multivariate experimental designs. The details are shown in Table 1.

[0049] Table 1 Control methods

[0050] Indicator name factor Fluidity Initial moisture content strength Curing agent dosage density Filler (EPS particles / air bubbles (blended with foaming agent) / rubber particles) Coagulation time Retarder

[0051] This design method can simultaneously control the fluidity, strength, density and setting time of the fluidized solidified backfill material, which is also the meaning of "controllable performance" in the name of the invention.

[0052] The test methods of various indicators in the embodiments are described as follows:

[0053] Fluidity test: The fluidity is measured with reference to the "Test Methods for Eametal and Eamelk" (JHS A313-1992) formulated by the Ministry of Construction of Japan. A cylindrical container (upper and lower diameter 80 mm, height 80 mm) is used to measure the horizontal expansion of the sludge. During the test, the cylindrical cylinder is placed on a horizontal glass plate, and the newly mixed soil is loaded into the cylindrical cylinder. No vibration is performed during the loading process, and the cylinder is completely filled by its own gravity. Flatten it with a scraper, lift the cylindrical cylinder vertically upwards gently, measure the flow diameter of the soil in two directions perpendicular to each other, and take the average value as the fluidity index.

[0054] Unconfined compressive strength test: The unconfined compressive strength test was carried out in accordance with the Geotechnical Test Method Standard (GBT 50123-2019). According to the size requirements of the UCS specimen in the Geotechnical Test Method Standard (GBT 50123-2019), a cylindrical test mold with a diameter of 39.1 mm and a height of 80 mm was customized. The unconfined compressive strength test was carried out using an unconfined pressure instrument.

[0055] Setting time test: Refer to the provisions of GB / T 1346-2011 Test Methods for Testing Water Consistency, Setting Time and Stability of Cement for Setting Time Test. The specimen is cured in a moisture curing box for the first measurement 30 minutes after adding water. During the measurement, take out the test mold from the moisture curing box and place it under the test needle, lowering the test needle to contact the surface of the cement paste. After tightening the screw for 1s to 2s, suddenly release it, and the test needle sinks vertically and freely into the specimen. Observe the pointer reading when the test needle stops sinking or releases the test needle for 30s. When the test needle sinks to 4mm±1mm from the bottom plate, it is considered to have reached the initial setting state.

[0056] Density test: The test specimen is a cylinder with a diameter of 39.1 mm and a height of 80 mm. Due to specimen deformation, the test volume of the specimen mixed with fillers (such as EPS particles / bubbles / rubber particles) must be measured before the strength test. Use a vernier caliper to measure the upper, middle and lower diameters of the specimen ( , , ) and the heights of the three angles ( , , ), and take their average values ​​as the diameter and height of the sample, respectively. The sample volume is calculated by calculation, and the calculation formula is shown in formula (1). The sample mass is measured by a 2000 g electronic balance with an accuracy of 0.1 g. The density of the PCFS sample is calculated according to formula (2). In order to make the measurement of the density of the PCFS sample more accurate, parallel tests are required. Three samples are made in each group, and their average value is taken as the final density value.

[0057] (1) (2)

[0058] Where: is the density of the PCFS sample (g / cm³); m is the mass of the PCFS sample (g); is the volume of the PCFS sample (cm 3 ).

[0059] The design method of the present invention specifically comprises the following steps:

[0060] Step (1) Determine the design fluidity of fluidized soil , Design Strength , Design setting time and design density .

[0061] According to the fluidity of the convective solidified soil in the specific project ,strength , setting time and density According to the regulations, determine the design value of each indicator. This value is usually a range, and generally requires: > , > , > , < .

[0062] Step (2) obtains the prediction formulas for the changes of fluidity, strength, density and setting time with single variables by conducting a fluidity test with initial water content as a single variable, an unconfined compressive strength test with curing agent dosage as a single variable, a density test with filler dosage as a single variable and a setting time test with retarder dosage as a single variable.

[0063] The prediction formula between the fluidity of fluidized solidified soil and the initial water content obtained through the fluidity test is:

[0064]

[0065] Where: is the fluidity of fluidized solidified soil, in mm; , are the fitting parameters, based on experimental calibration; is the initial moisture content, i.e. the ratio of cement to water;

[0066] The prediction formula between the strength of fluidized solidified soil and the amount of solidifying agent obtained through the unconfined compressive strength test is:

[0067]

[0068] Where: is the strength of fluidized solidified soil, in kPa; , are the fitting parameters, based on experimental calibration; is the curing agent dosage;

[0069] The prediction formula between the density of fluidized solidified soil and the amount of EPS particles obtained through density test is:

[0070]

[0071] Where: It is the density of fluidized solidified soil; is the density of soil; is the density of the filling; is the filling amount;

[0072] The prediction formula between the setting time of fluidized solidified soil and the amount of retarder obtained through the setting time test is:

[0073]

[0074] Where: is the setting time of fluidized solidified soil, in min; are the fitting parameters, based on experimental calibration; is the retarder dosage;

[0075] let = , = , = , , and then the corresponding moisture content, curing agent dosage, EPS dosage and retarder dosage are calculated based on the above prediction formula. Here, the moisture content, curing agent dosage, EPS dosage and retarder dosage are the mass ratios of water, curing agent, EPS particles and retarder to the soil used, respectively. On the basis of the preset total mass of soil, the initial , , , .

[0076] Keep = + + + While keeping the total mass of the material and the total mass of the soil unchanged, we change the proportional relationship between the components and conduct multivariate experiments.

[0077] (3) Based on the fluidity requirements, the fluidity prediction formula of fluidized solidified soil is obtained through fluidity tests to determine the optional ranges of initial moisture content, filler dosage, and curing agent dosage.

[0078] The prediction formula between the fluidity of fluidized solidified soil and the initial moisture content, the amount of curing agent and the amount of filler obtained through the fluidity test is:

[0079]

[0080] Where:

[0081] is the fluidity of fluidized solidified soil, in mm; is the initial moisture content, i.e. the mass content of water in the soil; is the curing agent dosage; is the filling amount; , , , , The fitting parameters are calibrated through experiments.

[0082] In one embodiment, the formula can be obtained as follows Figure 1 The ternary diagram shown is given by Figure 1 The optional range of curing agent, water and filler dosage when meeting the fluidity requirements can be obtained, thereby determining the proportional relationship among the three.

[0083] (4) Based on the strength requirements, a multivariate prediction formula for the strength of fluidized solidified soil is obtained through unconfined compression tests to determine the optional ranges of initial moisture content, filler content, and curing agent content.

[0084] The prediction formula of fluidized solidified soil strength and initial water content, curing agent dosage and filler dosage obtained through unconfined compressive strength test is:

[0085]

[0086] Where:

[0087] is the strength of fluidized solidified soil, in kPa; is the initial moisture content; is the curing agent dosage; is the filling amount; , , , , The fitting parameters are calibrated through experiments.

[0088] In one embodiment, the formula can be obtained as follows Figure 2 The ternary diagram shown is given by Figure 2 The ratio between the amount of curing agent, water and filler when the strength requirements are met can be obtained.

[0089] (5) Based on the setting time requirement, the setting time of the fluidized solidified soil is measured using a Vicat apparatus to determine the amount of retarder.

[0090] The prediction formula of setting time and retarder dosage of fluidized solidified soil obtained through setting time test is:

[0091]

[0092] Where:

[0093] is the setting time of fluidized solidified soil, in min; is the initial moisture content; is the retarder dosage; is the curing agent dosage; , , , , The fitting parameters are calibrated through experiments.

[0094] In one embodiment, the formula can be obtained as follows Figure 3 The ternary diagram shown is given by Figure 3 The proportional relationship between the amount of curing agent, water and retarder when the strength requirements are met can be obtained.

[0095] Example 2

[0096] In practical application:

[0097] Step 1: Determine the design fluidity of fluidized soil , Design Strength , Design setting time and design density .

[0098] Step 2: Obtain the changing rules of fluidity, strength, density and setting time through indoor tests, according to the formula:

[0099]

[0100]

[0101]

[0102]

[0103] let = , = , = , , and obtain the initial dosage: = + + + .

[0104] Step 3: The fluidity prediction formula for fluidized solidified soil is obtained through fluidity test as follows, and a ternary diagram is drawn to determine the optional ratio range between the curing agent, water and filler when the fluidity requirements are met.

[0105]

[0106] Step 4: Obtain the strength prediction formula of fluidized solidified soil through strength test, draw a ternary diagram, and draw a ternary diagram to determine the optional ratio range between the curing agent, water and EPS particles when the strength requirements are met.

[0107]

[0108] Step 5: Obtain the setting time prediction formula for fluidized solidified soil through setting time test, draw a ternary diagram, and draw a ternary diagram to determine the optional ratio range between the curing agent, water and retarder when the setting time requirements are met.

[0109]

[0110] Step 6: Combine the single variable prediction formula of fluidized solidified soil density with the optional proportion range confirmed in steps 3-5 to obtain the final water, EPS particle dosage, cement dosage and retarder dosage.

Claims

1. A design method for a fluid solidifying backfill material with controllable performance, characterized in that: include: Water, curing agent, retarder and filler for density adjustment are used as filler control components, and initial moisture content, curing agent dosage, filler dosage and retarder dosage are used as control variables; The single variable prediction formulas of fluidity and initial water content of fluidized solidified soil, strength and curing agent dosage of fluidized solidified soil, density and filler dosage of fluidized solidified soil, setting time and retarder dosage of fluidized solidified soil were constructed respectively. According to the design values ​​of fluidity, strength, setting time and density, combined with the preset total mass of soil, the corresponding single variable prediction formula is used to obtain the initial water mass, curing agent mass, filling material mass and retarder mass; Keeping the total mass of initial water, curing agent, filler and retarder, and the total mass of soil fixed, construct multivariate prediction formulas for fluidity, strength, setting time and at least three control variables of fluidized solidified soil; According to the design values ​​of fluidity, strength and setting time, the optional ratio range of the control variables in each of the multivariable prediction formulas is determined, and the optional ratio ranges of the control variables determined by multiple multivariable prediction formulas and the single variable prediction formula based on the density of the fluidized solidified soil and the filler dosage are taken as the union to obtain the dosage ratio range of the filler control component.

2. The design method according to claim 1, characterized in that: The single variable prediction formula of the fluidity and initial water content of the fluidized solidified soil is in a linear form; The single variable prediction formula for the strength of fluidized solidified soil and the amount of solidifying agent is in exponential form; The single variable prediction formula for the setting time of fluidized solidified soil and the amount of retarder is in exponential form; The single variable prediction formula for the density of fluidized solidified soil and the filler dosage is a calculation formula for the density of fluidized solidified soil established with the filler dosage as the independent variable and the soil material density and the filler density as fixed parameters.

3. The design method according to claim 1, characterized in that: Based on the fluidity test, strength test, setting time test and density test, single variable prediction formula and multivariable prediction formula of fluidity, strength, setting time, density and variables are established respectively.

4. The design method according to claim 1, characterized in that: The multivariable prediction formula is a multivariable prediction formula for fluidity, strength, setting time and three control variables of fluidized solidified soil.

5. The design method according to claim 4, characterized in that: The multivariate prediction formula includes: Multivariable prediction formula for fluidity of fluidized solidified soil and initial water content, curing agent dosage and filler dosage; Multivariate prediction formula for fluidized solidified soil strength and solidifying agent dosage, initial water content and filler dosage; A multivariate prediction formula for the setting time of fluidized solidified soil and the initial moisture content, the dosage of solidifying agent and the dosage of retarder.

6. The design method according to claim 5, characterized in that: The multivariate prediction formula is in the following form: The multivariate prediction formula of fluidity of fluidized solidified soil, initial water content, curing agent dosage and filler dosage is: ； Where: The fluidity of the fluidized solidified soil; is the initial moisture content; is the curing agent dosage; is the filling amount; , , , , For fitting parameters, calibrate them through experiments; The multivariate prediction formula of fluidized solidified soil strength and solidifying agent dosage, initial water content and filler dosage is: ； Where: It is the strength of fluidized solidified soil; is the initial moisture content; is the curing agent dosage; is the filling amount; , , , , For fitting parameters, calibrate them through experiments; The multivariate prediction formula of the setting time of fluidized solidified soil and the initial moisture content, the dosage of the solidifying agent and the dosage of the retarder is: ； Where: It is the setting time of fluidized solidified soil; is the initial moisture content; is the retarder dosage; is the curing agent dosage; , , , , The fitting parameters are calibrated through experiments.

7. The design method according to claim 1, characterized in that: By establishing a ternary diagram or a quaternary diagram for the obtained multivariate prediction formula, the optional ratio range of the variables determined in each ternary diagram or quaternary diagram is obtained, and the optional ratio range of the variables confirmed in all ternary diagrams or quaternary diagrams is taken as the union, the dosage ratio range of the filler regulating component is obtained.

8. The design method according to claim 1, characterized in that: The filler is EPS particles, air bubbles or rubber particles.

9. A fluidized solidified backfill material with controllable performance obtained by the design method according to any one of claims 1 to 8.

10. Application of the design method according to any one of claims 1 to 8 in fluidized backfill engineering.

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