Foundation backfill construction method based on on-site working condition dynamic allocation of flow state solidified soil

Abstract

The application relates to the technical field of foundation backfill construction, and provides a foundation backfill construction method for dynamically adjusting flow state solidified soil based on field working conditions. A reference mix proportion is determined under reference test conditions, a working condition adjustment relationship of water-solid ratio and solidified agent content when construction temperature, initial water content of raw soil and gravel particle content change alone or in combination is established; the current construction temperature, water content and gravel content are detected before each batch mixing, and the reference mix proportion is corrected to obtain a target mix proportion and field added water quality; the flow state solidified soil is prepared according to the target mix proportion, and is filled into the area to be backfilled after the initial flow expansion degree meets the requirements, and is solidified to form a backfill reinforced body. The application can dynamically adjust the mix proportion according to the field working conditions, so that the flow state solidified soil can keep the fluidity meeting the backfill filling requirements within the target construction time, and the compactness and bearing strength of the backfill body are improved.

Description

Technical Field

[0001] This invention relates to the field of foundation backfilling construction technology, and in particular to a foundation backfilling construction method based on dynamic allocation of fluidized solidified soil under on-site working conditions. Background Technology

[0002] In projects such as trench backfilling, foundation pit backfilling, underground structure perimeter backfilling, and roadbed backfilling, fluidized solidified soil is often used as a backfill material. Fluidized solidified soil is made by mixing a solidifying agent, water, and construction waste in a certain proportion to form a fluid backfill material that reaches a certain strength after solidification. It is then filled into the area to be backfilled by pumping or self-leveling and solidifies to form a backfill solidified body.

[0003] In the backfilling construction of fluidized bed solidified soil, the mix proportion directly affects the flowability, pumpability over time, and bearing strength of the backfill. In existing technologies, the mix proportion design of fluidized bed solidified soil is usually based on indoor standard conditions. For example, Chinese patent application CN121577861A discloses a method for determining the design mix proportion parameters of fluidized bed solidified soil. This method determines the low / high values ​​of the water-to-solid ratio and the lime-to-soil ratio by determining the liquid limit of the raw soil, prepares samples for flowability, bleeding rate, and solidified compressive strength tests, and establishes the functional relationship between performance parameters and the water-to-solid ratio and lime-to-soil ratio. CN121499749A discloses a method for determining the mix proportion parameters and the high and low limits of the slurry density of fluidized bed solidified soil, establishing a mathematical equation for the variation of test data with the mix proportion. In addition, there are methods for real-time monitoring and early warning adjustment by establishing a material ratio fluctuation curve model, as well as dynamic adjustment systems based on multi-source heterogeneous data fusion.

[0004] However, the aforementioned existing technologies all have the following shortcomings: First, the ambient temperature at the construction site differs significantly from the standard indoor conditions, ranging from 5 to 40°C. Increased temperature accelerates the hydration reaction rate of the curing agent, leading to a faster loss of fluidity in the solidified soil over time and a shorter pumpable time window. The mix proportions determined indoors do not consider changes in construction temperature. Directly using these proportions for backfilling in high-temperature environments may result in initial fluidity that is acceptable, but insufficient fluidity after transportation and pumping, making it impossible to successfully fill the backfilled area.

[0005] Second, the initial moisture content of the raw soil intended for backfill varies significantly due to differences in source, weather, and storage conditions. The initial moisture content of the raw soil directly affects the actual amount of water required to achieve the target flow spread. Indoor mix design is usually based on a fixed moisture content, without establishing a quantitative correction relationship between the initial moisture content and the amount of water added on site. This leads to deviations in the amount of water added during on-site backfilling, which may cause bleeding, segregation, or insufficient strength in the backfill.

[0006] Third, the content of crushed stone particles directly affects the flowability and mechanical properties of solidified fluid. Indoor mix design typically does not consider the content of crushed stone particles as an adjustment variable, resulting in inconsistent flowability and solidification strength of backfill under different crushed stone particle contents.

[0007] Furthermore, existing methods, after determining the mix proportion, only use the initial fluidity or slump as the construction control index, without taking the fluidity over time within the target construction period as a constraint condition for mix proportion design. This makes it difficult to ensure that the fluidized solidified soil still has the fluidity and filling capacity to meet the backfilling construction requirements when pumped to the area to be backfilled.

[0008] Therefore, it is necessary to propose a foundation backfilling construction method based on dynamic allocation of fluidized solidified soil according to on-site working conditions to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0009] The main objective of this invention is to provide a foundation backfilling construction method based on dynamic adjustment of fluidized solidified soil under on-site working conditions, in order to solve the technical problem of how to ensure that the fluidized solidified soil can maintain the fluidity required for backfilling within the target construction time and reach the design bearing strength after solidification when the ambient temperature, initial moisture content of the raw soil and content of crushed stone at the construction site fluctuate.

[0010] To achieve the above objectives, this invention provides a foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to on-site working conditions, comprising the following steps: S1. Under the reference test conditions, prepare fluidized solidified soil samples using raw soil, solidifying agent, and water intended for use in the backfill area, and determine the reference mix proportion that simultaneously satisfies the target initial flow spread, the minimum flow spread over time corresponding to the target construction time, and the unconfined compressive strength at the design age; wherein, the reference test conditions include the reference test temperature, the reference initial moisture content, and the reference crushed stone particle content, and the reference mix proportion includes the reference water-solid ratio and the reference solidifying agent dosage; S2, change one of the following factors: test temperature, initial moisture content of raw soil and crushed stone particle content, while keeping the other factors at the baseline value, and establish a single-factor adjustment relationship; then change at least two of the factors simultaneously to conduct a combined working condition test, and correct the single-factor adjustment relationship based on the combined working condition test results to obtain the working condition adjustment relationship; S3, detect the current construction temperature, the current initial moisture content of the raw soil and the current crushed stone particle content, adjust the benchmark water-solid ratio and the benchmark curing agent dosage according to the working condition adjustment relationship, obtain the target water-solid ratio and the target curing agent dosage, and determine the quality of the on-site external water; S4. Prepare fluidized solidified soil according to the target water-solid ratio, the target solidifying agent dosage and the mass of on-site added water. After the initial flow spread of the fluidized solidified soil meets the target initial flow spread, fill the fluidized solidified soil into the area to be backfilled to form a backfill solidified body that meets the design age unconfined compressive strength.

[0011] Preferably, step S1 includes the following steps: S11, the raw soil intended for the backfill area is adjusted to the reference initial moisture content and reference crushed stone particle content, and the adjusted raw soil is placed at the reference test temperature for temperature equilibration; wherein, the crushed stone particle content is the mass percentage of the dry mass of particles with a diameter greater than 5 mm in the raw soil to the dry mass of the raw soil. S12, multiple groups of fluidized solidified soil samples with different water-to-solid ratios and different amounts of solidifying agent were prepared using the adjusted raw soil, solidifying agent, and water; wherein, the amount of solidifying agent was the mass percentage of the solidifying agent to the dry mass of the raw soil. S13, the initial flow spread of each group of fluidized solidified soil samples, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age are tested respectively; the target construction time is the longest time allowed for the fluidized solidified soil from the completion of mixing to entering the backfill area. S14. From the combinations of water-to-solid ratio and curing agent dosage that simultaneously satisfy the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age, select the combination with the lowest curing agent dosage; when the curing agent dosage is the same, select the combination with the lowest water-to-solid ratio, and determine the water-to-solid ratio and curing agent dosage in the selected combination as the reference water-to-solid ratio and reference curing agent dosage, respectively.

[0012] Preferably, step S2 includes the following steps: S21. Change one of the following factors: test temperature, initial moisture content of raw soil and crushed stone content, while keeping the other factors at the baseline value, to prepare multiple groups of single-factor samples. S22, the initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age of each group of single-factor samples are detected respectively. By looking up tables, interpolation, or function fitting, the water-solid ratio correction coefficient and the solidifier dosage correction coefficient corresponding to the test temperature, the initial moisture content of the raw soil, and the crushed stone particle content are established respectively as single-factor adjustment relationships. S23, select at least two of the following factors to change simultaneously: test temperature, initial moisture content of raw soil and crushed stone particle content, prepare multiple sets of combined working condition samples, and test the initial flow spread, the flow spread over time after the target construction time and the unconfined compressive strength after the design age of each set of combined working condition samples. S24. Determine the combined working condition correction coefficient based on the test results of the combined working condition sample, and use the combined working condition correction coefficient to correct the single factor adjustment relationship to obtain the working condition adjustment relationship.

[0013] Preferably, step S22 includes the following steps: S221, at each test temperature level, prepare multiple sets of samples with different water-to-solid ratios and different curing agent dosages. From the multiple sets of samples, determine the temperature single-factor target mix proportion that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age. Determine the water-to-solid ratio temperature correction coefficient by the ratio of the water-to-solid ratio in the temperature single-factor target mix proportion to the reference water-to-solid ratio, and determine the curing agent dosage temperature correction coefficient by the ratio of the curing agent dosage in the temperature single-factor target mix proportion to the reference curing agent dosage. S222, at each initial moisture content level of raw soil, multiple groups of samples with different water-to-solid ratios and different amounts of curing agent are prepared. From the multiple groups of samples, a single-factor target mix proportion with moisture content that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age is determined. The water-to-solid ratio moisture content correction coefficient is determined by the ratio of the water-to-solid ratio in the single-factor target mix proportion with the reference water-to-solid ratio, and the curing agent content moisture content correction coefficient is determined by the ratio of the curing agent content in the single-factor target mix proportion with the reference curing agent content. S223, at each level of crushed stone particle content, multiple groups of samples with different water-to-solid ratios and different amounts of curing agent were prepared. From these multiple groups of samples, a single-factor target mix proportion for crushed stone content that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age was determined. The water-to-solid ratio crushed stone content correction coefficient was determined by the ratio of the water-to-solid ratio in the single-factor target mix proportion for crushed stone content to the reference water-to-solid ratio. The curing agent content crushed stone content correction coefficient was determined by the ratio of the amount of curing agent in the single-factor target mix proportion for crushed stone content to the reference amount of curing agent. S224, the correction coefficients for multiple test temperature levels, multiple moisture content levels, and multiple crushed stone particle content levels are fitted to obtain the single-factor adjustment relationship.

[0014] Preferably, the combined operating condition test specimen includes at least one of the following: The test specimen under the first combined working condition was tested with the temperature and initial moisture content of the raw soil changing together, and the crushed stone particle content being maintained at the baseline crushed stone particle content. The second combined working condition sample was tested under conditions in which the test temperature and the content of crushed stone particles changed together, and the initial moisture content of the raw soil was kept at the baseline initial moisture content. The third combination of working conditions was a test sample in which the initial moisture content of the raw soil and the content of crushed stone particles changed together, and the test temperature was kept at the reference test temperature. The fourth combination of working conditions was tested, with variations in test temperature, initial moisture content of raw soil, and gravel particle content.

[0015] Preferably, the combined operating condition correction factor includes the water-to-solid ratio combined operating condition correction factor and the curing agent dosage combined operating condition correction factor; For each combination of working conditions, the predicted water-to-solid ratio and the predicted curing agent dosage are calculated according to the single-factor adjustment relationship. Multiple sets of samples with different water-to-solid ratios and different curing agent dosages are prepared. From the multiple sets of samples, the target mix proportion for the combination of working conditions that simultaneously meets the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age is determined. The water-to-solid ratio combination working condition correction coefficient is the ratio of the measured target water-to-solid ratio to the predicted water-to-solid ratio in the target mix proportion of the combination working condition; The correction coefficient for the curing agent dosage combination working condition is the ratio of the measured target curing agent dosage to the predicted curing agent dosage in the target mix proportion of the combination working condition.

[0016] Preferably, the target water-to-solid ratio and the target curing agent dosage are determined according to the following relationship: ; ; In the formula, For the target water-to-solid ratio, As the baseline water-to-solid ratio, , and These are the water-to-solid ratio temperature correction factor, water-to-solid ratio moisture content correction factor, and water-to-solid ratio crushed stone content correction factor, respectively. This is the correction factor for the water-to-solid ratio combination working condition; The target curing agent dosage, As a baseline, the amount of curing agent added. , and These are the correction factors for curing agent dosage based on temperature, curing agent dosage based on moisture content, and curing agent dosage based on crushed stone content, respectively. This is a correction factor for the combined working conditions of curing agent dosage. When the corresponding working condition factor does not deviate from the benchmark test conditions, or the test results show that the corresponding factor does not need to be corrected, the corresponding correction factor is taken as 1; when only one factor of the field working condition deviates from the benchmark test conditions, the combined working condition correction factor is taken as 1.

[0017] Preferably, the mass of the on-site externally supplied water is determined according to the following relationship: ; In the formula, For the quality of water supplied on site, The dry soil quality of the raw material for the current construction batch. This represents the initial moisture content of the current raw soil. and All calculations are performed using decimals. When the calculated mass of on-site added water is less than 0, the raw soil is subjected to at least one treatment: dehydration, drying, or mixing with similar dry soil, until the existing water mass in the raw soil is not greater than the total water mass determined according to the target water-solid ratio.

[0018] Preferably, the curing agent is a composite curing agent composed of cement and mineral powder, and the mineral powder accounts for 50% to 70% of the mass of the curing agent.

[0019] Preferably, the area to be backfilled is a trench backfilling area, a foundation pit backfilling area, a backfilling area around an underground structure, or a roadbed backfilling area.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention establishes a working condition adjustment relationship with a benchmark mix proportion as a reference through benchmark tests. Before each batch of mixing, the current construction temperature, initial moisture content of the raw soil, and crushed stone particle content are tested. Based on this, the benchmark water-solid ratio and benchmark solidifying agent dosage are adjusted to adapt the mix proportion to the current site conditions. Furthermore, by combining the working condition adjustment relationship, the interactive influence deviation when two or more factors change simultaneously is compensated, thereby improving the accuracy of mix proportion adjustment under complex working conditions.

[0021] (2) The present invention uses the minimum time-dependent flow expansion corresponding to the target construction time as the constraint condition for determining the benchmark mix ratio and establishing the working condition adjustment relationship, so as to ensure that the fluidized solidified soil always maintains the flow filling capacity that meets the backfill requirements during transportation, waiting and pumping.

[0022] (3) This invention uses the initial moisture content of the raw soil as the basis for determining the quality of the added water on site, so that the indoor design water-solid ratio is transformed into an executable construction parameter, reducing bleeding or insufficient strength caused by fluctuations in moisture content. At the same time, the content of crushed stone particles is incorporated into the working condition adjustment relationship to dynamically determine the amount of solidifying agent, thereby improving the strength stability of the backfill under different crushed stone particle contents.

[0023] (4) This invention dynamically adjusts the mix ratio to make the fluid solidified soil fill densely. The backfill solidified after solidification meets the design bearing strength and is suitable for foundation backfilling projects in various soil types and construction environments. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 This is a schematic flowchart of one embodiment of the present invention.

[0026] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] In this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0030] Please refer to Figure 1 The present invention provides a foundation backfilling construction method based on dynamic allocation of fluidized solidified soil under on-site working conditions, comprising the following steps: S1. Under the reference test conditions, prepare fluidized solidified soil samples using raw soil, solidifying agent, and water intended for use in the backfill area, and determine the reference mix proportion that simultaneously satisfies the target initial flow spread, the minimum flow spread over time corresponding to the target construction time, and the unconfined compressive strength at the design age; wherein, the reference test conditions include the reference test temperature, the reference initial moisture content, and the reference crushed stone particle content, and the reference mix proportion includes the reference water-solid ratio and the reference solidifying agent dosage; S2, change one of the following factors: test temperature, initial moisture content of raw soil and crushed stone particle content, while keeping the other factors at the baseline value, and establish a single-factor adjustment relationship; then change at least two of the factors simultaneously to conduct a combined working condition test, and correct the single-factor adjustment relationship based on the combined working condition test results to obtain the working condition adjustment relationship; S3. Detect the current construction temperature, the initial moisture content of the raw soil, and the current gravel particle content. Adjust the baseline water-to-solid ratio and baseline solidifier dosage according to the aforementioned working condition adjustment relationship to obtain the target water-to-solid ratio and target solidifier dosage, and determine the quality of on-site added water. Specifically, detect the current construction temperature, the initial moisture content of the raw soil, and the current gravel particle content to characterize the actual engineering conditions of the current construction batch. Compare these with the baseline test temperature, baseline initial moisture content, and baseline gravel particle content in the baseline test conditions to determine the deviation of each factor. Then, determine the target water-to-solid ratio and target solidifier dosage according to the working condition adjustment relationship. The current construction temperature can be measured using a thermometer or an ambient temperature and humidity sensor; the initial moisture content of the raw soil can be measured using microwave drying, alcohol combustion, or rapid drying methods; and the current gravel particle content can be measured using a sieve analysis method.

[0031] S4. Prepare fluidized solidified soil according to the target water-solid ratio, the target solidifying agent dosage and the mass of on-site added water. After the initial flow spread of the fluidized solidified soil meets the target initial flow spread, fill the fluidized solidified soil into the area to be backfilled to form a backfill solidified body that meets the design age unconfined compressive strength.

[0032] Preferably, a small batch of fluidized solidified soil is prepared according to the target water-to-solid ratio, the target curing agent dosage, and the amount of water added on-site, and its initial flow spread and the flow spread over time after the target construction time are tested.

[0033] When the initial flow spread is lower than the lower limit of the target initial flow spread, the amount of water added on site is gradually increased within the allowable adjustment range determined by pre-tests; when the initial flow spread is higher than the upper limit of the target initial flow spread, the amount of water added on site is reduced or raw material soil and solidifying agent are added according to the target ratio.

[0034] When the flow expansion after the target construction time is lower than the minimum flow expansion after the target construction time, the target water-to-solid ratio, curing agent dosage, or the ratio of cement to mineral powder in the curing agent should be readjusted, and the amount of water added on site should be recalculated.

[0035] After each adjustment, a new batch of test mixes was prepared and the initial flow spread and the flow spread over time were tested until both indicators met the requirements.

[0036] On-site water addition adjustments must not cause the actual water-to-solid ratio to exceed the allowable upper limit determined in advance through unconfined compressive strength testing. For adjustment schemes exceeding the allowable water-to-solid ratio range, the curing agent dosage should be readjusted, and strength verification specimens should be prepared. Flowability should not be achieved solely by increasing the amount of water added on-site.

[0037] After the trial batch passes verification, the final construction batch of fluidized solidified soil is prepared according to the target water-to-solid ratio, target solidifying agent dosage, and on-site added water volume determined in the trial batch. The initial flowability of the final construction batch is tested before filling; if the construction temperature, initial moisture content of the raw soil, gravel particle content, transportation time, or pumping distance changes beyond the preset range, the trial mixing verification is repeated.

[0038] This invention prepares trial batches of fluidized solidified soil according to the target water-to-solid ratio, target solidifying agent dosage, and on-site added water mass. The initial flow spread and the flow spread over time after the target construction period are tested. After the initial flow spread is within the target initial flow spread and the flow spread over time is not lower than the minimum flow spread over time, a formal construction batch of fluidized solidified soil is prepared according to the final mix proportion determined for the trial batch. The formal construction batch of fluidized solidified soil is filled into the area to be backfilled, and strength specimens from the same batch are retained. After reaching the design age, the unconfined compressive strength of the strength specimens from the same batch and / or the core samples of the backfill reinforcement is tested.

[0039] In this invention, a working condition adjustment relationship is pre-established based on a benchmark mix proportion through benchmark tests. Before each batch of mixing, the current construction temperature, initial moisture content of the raw soil, and crushed stone particle content are measured. Based on this, the benchmark water-to-solid ratio and benchmark solidifier dosage are adjusted to adapt the mix proportion to the current site conditions. By combining the working condition adjustment relationship, the interactive influence deviation when two or more factors change simultaneously is compensated, improving the accuracy of mix proportion adjustment under complex working conditions.

[0040] By using the minimum time-dependent flow expansion corresponding to the target construction time as a constraint condition for determining the benchmark mix proportion and establishing the working condition adjustment relationship, it is ensured that the fluidized solidified soil maintains its flow and filling capacity to meet backfill requirements throughout the transportation, waiting and pumping process.

[0041] By using the initial moisture content of the raw soil as the basis for determining the quality of on-site applied water, the indoor design water-solid ratio is transformed into an executable construction parameter, reducing bleeding or insufficient strength caused by moisture content fluctuations. Simultaneously, the crushed stone particle content is incorporated into the working condition adjustment relationship to dynamically determine the amount of solidifying agent, improving the strength stability of the backfill under different crushed stone particle contents.

[0042] By dynamically adjusting the mix ratio, the fluidized solidified soil is made densely packed, and the backfill solidified after solidification meets the design bearing strength, making it suitable for foundation backfilling projects with various soil types and construction environments.

[0043] In a preferred embodiment, S1 includes the following steps: S11, the raw soil intended for the backfill area is adjusted to the reference initial moisture content and reference crushed stone particle content, and the adjusted raw soil is placed at the reference test temperature for temperature equilibration; wherein, the crushed stone particle content is the mass percentage of the dry mass of particles with a diameter greater than 5 mm in the raw soil to the dry mass of the raw soil. Specifically, the raw soil intended for the backfill area is selected as the test object. This raw soil can be trench excavation soil, foundation pit excavation soil, roadbed construction waste soil, or other engineering spoil intended for foundation backfilling. Before conducting the benchmark mix design test, the initial moisture content and gravel particle content of the raw soil are determined. The initial moisture content can be determined using the oven-drying method, microwave drying method, or alcohol combustion method; the gravel particle content can be determined using the sieving method. The gravel particles are preferably particles with a diameter greater than 5 mm, and the gravel particle content is the percentage of the dry mass of particles with a diameter greater than 5 mm in the raw soil relative to the dry mass of the raw soil.

[0044] When the actual initial moisture content of the raw soil is lower than the benchmark initial moisture content, the moisture content can be increased by spraying water into the raw soil and allowing it to sit for a period of time. When the actual initial moisture content of the raw soil is higher than the benchmark initial moisture content, the moisture content can be reduced by natural air-drying, low-temperature drying, or mixing in similar dry soil, so that the raw soil reaches the benchmark initial moisture content. Similarly, when the actual crushed stone particle content of the raw soil is lower than the benchmark crushed stone particle content, crushed stone particles of the same particle size range can be mixed into the raw soil. When the actual crushed stone particle content of the raw soil is higher than the benchmark crushed stone particle content, some crushed stone particles can be removed by sieving, so that the raw soil reaches the benchmark crushed stone particle content.

[0045] The adjusted raw soil is placed at the reference test temperature to ensure that the raw soil temperature matches the reference test temperature before the mixing test is conducted. The reference test temperature can be selected as 25±2℃. By standardizing the initial moisture content, particle composition, and temperature conditions of the raw soil, the reference mix proportion is obtained under clear and repeatable reference test conditions, avoiding inaccuracies in the reference mix proportion due to inconsistent raw soil conditions.

[0046] S12, multiple groups of fluidized solidified soil samples with different water-to-solid ratios and different amounts of solidifying agent were prepared using the adjusted raw soil, solidifying agent, and water; wherein, the amount of solidifying agent was the mass percentage of the solidifying agent to the dry mass of the raw soil. The curing agent can be cement, mineral powder, or a composite curing agent composed of cement and mineral powder. Preferably, the curing agent is a composite curing agent composed of cement and mineral powder, and the mineral powder accounts for 50% to 70% of the mass of the curing agent.

[0047] The water-to-solid ratio is the ratio of the total water mass in the fluidized solidified soil to the sum of the dry soil mass of the raw material and the solidifying agent mass. The total water mass includes the existing water mass in the raw material and the mass of water added on-site. The solidifying agent dosage is the mass percentage of the solidifying agent mass to the dry soil mass of the raw material, which mainly affects the unconfined compressive strength of the fluidized solidified soil after solidification, and also affects the material's flow loss over time.

[0048] Specifically, when preparing multiple groups of fluidized solidified soil samples, multiple water-to-solid ratio levels and multiple solidifier dosage levels are set. Except for the water-to-solid ratio and solidifier dosage, the material composition and preparation conditions are kept consistent across all groups of samples. For example, three water-to-solid ratio levels (low, medium, and high) and three solidifier dosage levels (low, medium, and high) can be set to form multiple combinations of water-to-solid ratio and solidifier dosage. Each combination is mixed using the same mixing time and method to minimize the impact of differences in mixing processes on the flow spread and strength results.

[0049] During the mixing process, the raw soil and the curing agent are first dry-mixed evenly, and then water is added for wet mixing until a uniform fluidized solidified soil mixture is formed. If necessary, fibers or dispersants can be added, but when determining the benchmark mix proportion, the types and amounts of fibers and dispersants in each group of samples should be kept consistent to ensure that the water-to-solid ratio and the amount of curing agent are the main factors of variation.

[0050] S13, the initial flow spread of each group of fluidized solidified soil samples, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age are tested respectively; the target construction time is the longest time allowed for the fluidized solidified soil from the completion of mixing to entering the backfill area. The initial flow spread is used to evaluate the initial flow and filling capacity of the fluidized solidified soil after mixing. The larger the initial flow spread, the easier the fluidized solidified soil is to pump, flow, and fill voids before entering the backfill area; if the initial flow spread is too low, it may lead to difficulties in pipeline transportation or incomplete filling of the backfill area.

[0051] The target construction time is the maximum allowable time from the completion of mixing of the fluidized solidified soil to its entry into the backfill area. It can be determined based on the on-site mixing location, transportation distance, pumping distance, construction waiting time, and backfilling organization method. The time-dependent flow spread is used to evaluate the degree to which the fluidized solidified soil retains its flow and filling capacity after the target construction time. By testing the time-dependent flow spread, the problem of only having a satisfactory initial flow spread but then experiencing excessive fluidity loss after transportation or waiting, thus failing to successfully fill the backfill area, can be avoided.

[0052] Unconfined compressive strength is used to evaluate the load-bearing capacity of the backfill solidified by solidified fluidized soil. Testing can be conducted at 7 days, 28 days, or other design ages, depending on project requirements. The 28-day unconfined compressive strength is preferred as the design control indicator. During testing, the fluidized soil sample can be prepared into specimens of specified dimensions and cured under specified conditions to the target age before loading tests.

[0053] The reference mix proportion of the present invention takes into account the initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength at the design age, thus avoiding the problem of traditional solutions that only focus on the initial flowability or final strength while ignoring the construction time window.

[0054] S14. From the combinations of water-to-solid ratio and curing agent dosage that simultaneously satisfy the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age, select the combination with the lowest curing agent dosage; when the curing agent dosage is the same, select the combination with the lowest water-to-solid ratio, and determine the water-to-solid ratio and curing agent dosage in the selected combination as the reference water-to-solid ratio and reference curing agent dosage, respectively.

[0055] Among multiple candidate combinations, the combination with the lowest curing agent content is selected. The water-to-solid ratio in this combination is determined as the baseline water-to-solid ratio, and the curing agent content in this combination is determined as the baseline curing agent content, thereby obtaining the baseline mix proportion. Using the candidate combination with the lowest curing agent content can reduce material costs, mitigate the risk of flow loss over time due to excessively rapid hydration, and avoid problems such as premature thickening of the material and shortened pumping window caused by excessive curing agent, while meeting the requirements for flow filling capacity, flow retention over time, and post-curing strength.

[0056] In a preferred embodiment, S2 includes the following steps: S21. Change one of the following factors: test temperature, initial moisture content of raw soil and crushed stone content, while keeping the other factors at the baseline value, to prepare multiple groups of single-factor samples. Multiple single-factor samples were prepared by varying the test temperature, initial moisture content of the raw soil, and gravel particle content, while keeping the other two conditions constant. For example, under the condition that the initial moisture content of the raw soil and the gravel particle content are kept at the baseline initial moisture content and baseline gravel particle content, multiple test temperature levels such as low temperature, normal temperature, and high temperature were set to prepare single-factor samples under temperature conditions. The single-factor samples under the moisture content condition and the single-factor samples under the gravel particle content condition were prepared according to the same logic, that is, only one factor was changed each time, while the other factors remained at the baseline values. The initial mix proportions of each group of single-factor samples were the same as those of the baseline sample, and the preparation process was also kept consistent to ensure that the differences between the test results were caused only by the change of a single factor. After preparation, the initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength at the design age of each group of single-factor samples were tested.

[0057] S22, the initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age of each group of single-factor samples are detected respectively. By looking up tables, interpolation, or function fitting, the water-solid ratio correction coefficient and the solidifier dosage correction coefficient corresponding to the test temperature, the initial moisture content of the raw soil, and the crushed stone particle content are established respectively as single-factor adjustment relationships. From the test combinations that simultaneously meet the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age under each single-factor working condition, select the test combination with the lowest curing agent dosage; when the curing agent dosage is the same, select the test combination with the lowest water-to-solid ratio that meets the flow spread requirement, and determine the selected test combination as the single-factor target mix proportion under the corresponding single-factor working condition.

[0058] The ratio of the water-to-solid ratio to the reference water-to-solid ratio in the single-factor target mix proportion is determined as the water-to-solid ratio correction coefficient corresponding to the corresponding working condition factor, and the ratio of the curing agent dosage to the reference curing agent dosage in the single-factor target mix proportion is determined as the curing agent dosage correction coefficient corresponding to the corresponding working condition factor.

[0059] Based on the correction coefficients obtained under different operating conditions, a single-factor adjustment relationship is established through a segmented value table, linear interpolation, or function fitting.

[0060] S23, select at least two of the following factors to change simultaneously: test temperature, initial moisture content of raw soil and crushed stone particle content, prepare multiple sets of combined working condition samples, and test the initial flow spread, the flow spread over time after the target construction time and the unconfined compressive strength after the design age of each set of combined working condition samples. S24. Determine the combined working condition correction coefficient based on the test results of the combined working condition sample, and use the combined working condition correction coefficient to correct the single factor adjustment relationship to obtain the working condition adjustment relationship.

[0061] In a preferred embodiment, S22 includes the following steps: S221, at each test temperature level, prepare multiple sets of samples with different water-to-solid ratios and different curing agent dosages. From the multiple sets of samples, determine the temperature single-factor target mix proportion that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age. Determine the water-to-solid ratio temperature correction coefficient by the ratio of the water-to-solid ratio in the temperature single-factor target mix proportion to the reference water-to-solid ratio, and determine the curing agent dosage temperature correction coefficient by the ratio of the curing agent dosage in the temperature single-factor target mix proportion to the reference curing agent dosage. Using the test results of the reference sample as a reference, single-factor samples prepared at different test temperatures were selected, and the initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength after curing were tested respectively. The test results of each group of single-factor samples were compared with the test results of the reference sample. When the test temperature increased, resulting in a decrease in the flow spread over time, the loss of flowability was compensated by increasing the water-to-solid ratio, and the curing agent dosage was adjusted simultaneously to maintain the matching relationship between the water-to-solid ratio and the curing agent dosage, ensuring that the strength after curing meets the design requirements. When the test temperature decreased, resulting in insufficient strength development after curing, the insufficient strength was compensated by increasing the curing agent dosage. From this, the temperature correction coefficients for the water-to-solid ratio and the curing agent dosage can be obtained.

[0062] S222, at each initial moisture content level of raw soil, multiple groups of samples with different water-to-solid ratios and different amounts of curing agent are prepared. From the multiple groups of samples, a single-factor target mix proportion with moisture content that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age is determined. The water-to-solid ratio moisture content correction coefficient is determined by the ratio of the water-to-solid ratio in the single-factor target mix proportion with the reference water-to-solid ratio, and the curing agent content moisture content correction coefficient is determined by the ratio of the curing agent content in the single-factor target mix proportion with the reference curing agent content. The test results of each group of single-factor samples were compared with those of the reference sample. When the initial moisture content of the raw soil increased, the existing water content of the raw soil increased, and the amount of additional water required to reach the target initial flow spread decreased; when the initial moisture content of the raw soil decreased, the amount of additional water required to reach the target initial flow spread increased. If the change in moisture content caused the unconfined compressive strength after curing to deviate from the design requirements, the amount of curing agent was adjusted accordingly. Thus, the water-to-solid ratio moisture content correction coefficient and the curing agent dosage moisture content correction coefficient can be obtained.

[0063] S223, at each level of crushed stone particle content, multiple groups of samples with different water-to-solid ratios and different amounts of curing agent were prepared. From these multiple groups of samples, a single-factor target mix proportion for crushed stone content that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age was determined. The water-to-solid ratio crushed stone content correction coefficient was determined by the ratio of the water-to-solid ratio in the single-factor target mix proportion for crushed stone content to the reference water-to-solid ratio. The curing agent content crushed stone content correction coefficient was determined by the ratio of the amount of curing agent in the single-factor target mix proportion for crushed stone content to the reference amount of curing agent. The test results of each group of single-factor samples were compared with the test results of the reference samples. When the increased content of crushed stone particles led to a decrease in the flowability of the solidified soil, the insufficient flowability was compensated by adjusting the water-to-solid ratio; when the increased content of crushed stone particles led to insufficient slurry coating or insufficient post-curing strength, the strength was compensated by increasing the dosage of curing agent. Thus, the correction coefficients for water-to-solid ratio and crushed stone content, and the correction coefficients for curing agent dosage and crushed stone content, can be obtained.

[0064] S224, the correction coefficients for multiple test temperature levels, multiple moisture content levels, and multiple crushed stone particle content levels are fitted to obtain the single-factor adjustment relationship.

[0065] Preferably, a quadratic function is used to fit the temperature correction coefficients for the water-to-solid ratio and the curing agent dosage, with the test temperature as the independent variable; a linear function is used to fit the water-to-solid ratio moisture content correction coefficients and the curing agent dosage moisture content correction coefficients, with the initial moisture content of the raw soil as the independent variable; and a quadratic function is used to fit the crushed stone content correction coefficients for the water-to-solid ratio and the curing agent dosage. The least squares method is used to solve for the undetermined constants in each function. Specific function expressions are given in the following embodiments, thus obtaining the temperature adjustment relationship, moisture content adjustment relationship, and crushed stone content adjustment relationship, which together serve as single-factor adjustment relationships. Subsequently, based on the on-site measured construction temperature, initial moisture content of the raw soil, and crushed stone content, the corresponding correction coefficients can be calculated by substituting them into the above function relationships.

[0066] The three types of adjustment relationships in this embodiment are based on the reference sample, and the initial flow spread, the flow spread over time, and the unconfined compressive strength at the design age are used as evaluation indicators. This can provide an feasible basis for subsequent correction of the reference water-solid ratio and the reference curing agent dosage according to the on-site working conditions.

[0067] It is worth noting that in single-factor experiments, only one factor changes, while the other two remain at the baseline conditions. That is, single-factor experiments can obtain the temperature adjustment relationship, moisture content adjustment relationship, and aggregate content adjustment relationship separately, but they can only reflect the effect of each factor changing individually. In actual foundation backfilling construction, the construction temperature, initial moisture content of the raw soil, and aggregate content may all deviate from the baseline test conditions simultaneously. For example, high temperatures accelerate the hydration reaction of the curing agent and accelerate the loss of flow spread over time, while high moisture content changes the actual amount of water added required to achieve the target initial flow spread. When adjusting the mix proportions based solely on the two single-factor adjustment relationships, the flow spread over time or the unconfined compressive strength after curing of the solidified soil may deviate from the performance target.

[0068] The purpose of the combined working condition test specimens of the present invention is not to find a fixed optimal ratio, but to test whether the water-solid ratio and curing agent dosage determined according to the single-factor adjustment relationship can still meet the target initial flow spread, minimum flow spread over time and unconfined compressive strength at the design age when two or three field working conditions change together.

[0069] As a preferred embodiment, the combined operating condition test sample includes at least one of the following: The test specimen under the first combined working condition was tested with the temperature and initial moisture content of the raw soil changing together, and the crushed stone particle content being maintained at the baseline crushed stone particle content. The second combined working condition sample was tested under conditions in which the test temperature and the content of crushed stone particles changed together, and the initial moisture content of the raw soil was kept at the baseline initial moisture content. The third combination of working conditions was a test sample in which the initial moisture content of the raw soil and the content of crushed stone particles changed together, and the test temperature was kept at the reference test temperature. The fourth combination of working conditions was tested, with variations in test temperature, initial moisture content of raw soil, and gravel particle content.

[0070] Furthermore, the combined operating condition correction factor includes the water-to-solid ratio combined operating condition correction factor and the curing agent dosage combined operating condition correction factor; For each combination of working conditions, the predicted water-to-solid ratio and the predicted curing agent dosage are calculated according to the single-factor adjustment relationship. Multiple sets of samples with different water-to-solid ratios and different curing agent dosages are prepared. From the multiple sets of samples, the target mix proportion for the combination of working conditions that simultaneously meets the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age is determined. The water-to-solid ratio combination working condition correction coefficient is the ratio of the measured target water-to-solid ratio to the predicted water-to-solid ratio in the target mix proportion of the combination working condition; The correction coefficient for the curing agent dosage combination working condition is the ratio of the measured target curing agent dosage to the predicted curing agent dosage in the target mix proportion of the combination working condition.

[0071] Specifically, the water-to-solid ratio correction coefficients corresponding to each variable factor in the combined working condition in the single-factor adjustment relationship are multiplied together, and then multiplied with the reference water-to-solid ratio to obtain the predicted water-to-solid ratio; the curing agent dosage correction coefficients corresponding to each variable factor in the combined working condition in the single-factor adjustment relationship are multiplied together, and then multiplied with the reference curing agent dosage to obtain the predicted curing agent dosage.

[0072] Using the predicted water-to-solid ratio and predicted curing agent dosage as references, multiple groups of samples with different water-to-solid ratios and curing agent dosages were prepared. The initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age were tested for each group of samples. From the multiple groups of samples, a combination that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age was selected as the target mix proportion for that combined working condition. During the selection process, if multiple combinations met the conditions, the combination with the lowest curing agent dosage was selected; when the curing agent dosages were the same, the combination with the lowest water-to-solid ratio was selected.

[0073] Dividing the water-to-solid ratio in the target mix proportion for combined operating conditions by the predicted water-to-solid ratio yields the water-to-solid ratio correction coefficient for combined operating conditions; dividing the curing agent dosage in the target mix proportion for combined operating conditions by the predicted curing agent dosage yields the curing agent dosage correction coefficient for combined operating conditions. The predicted water-to-solid ratio and predicted curing agent dosage are theoretical values ​​obtained based on the single-factor independence assumption, while the target mix proportion for combined operating conditions is the measured value required to actually meet the target performance under combined operating conditions. The ratio of the two quantifies the deviation between the single-factor independence assumption and the actual requirements of combined operating conditions, and is used to correct the deviation caused by the interaction of single-factor adjustment relationships.

[0074] Furthermore, the target water-to-solid ratio and the target curing agent dosage are determined according to the following relationship: ; ; In the formula, For the target water-to-solid ratio, As the baseline water-to-solid ratio, , and These are the water-to-solid ratio temperature correction factor, water-to-solid ratio moisture content correction factor, and water-to-solid ratio crushed stone content correction factor, respectively. This is the correction factor for the water-to-solid ratio combination working condition; The target curing agent dosage, As a baseline, the amount of curing agent added. , and These are the correction factors for curing agent dosage based on temperature, curing agent dosage based on moisture content, and curing agent dosage based on crushed stone content, respectively. This is a correction factor for the combined working conditions of curing agent dosage. The initial moisture content of the raw soil is used, on the one hand, to calculate the existing water mass in the raw soil, and on the other hand, to compensate for the influence of different raw soil moisture contents on the dispersion state, flowability over time, and solidification strength of the fluidized solidified soil slurry, based on the pre-established working condition adjustment relationship.

[0075] When the corresponding operating condition factors do not deviate from the baseline test conditions (i.e., when the corresponding field operating condition parameters are equal to the corresponding baseline values), or when the test results show that the corresponding factors do not require correction (i.e., when the baseline mix proportion can simultaneously meet the target initial flow spread range, minimum flow spread over time, and unconfined compressive strength at the design age under single-factor operating conditions), the corresponding correction factor is taken as 1; when only one factor of the field operating conditions deviates from the baseline test conditions, the combined operating condition correction factor is taken as 1. All correction factors are expressed as ratios. When the correction factor is greater than 1, it indicates that the water-to-solid ratio or the amount of curing agent needs to be increased; when the correction factor is equal to 1, it indicates that no correction is needed; when the correction factor is less than 1, it indicates that the water-to-solid ratio or the amount of curing agent can be appropriately reduced.

[0076] When the corresponding operating condition factor does not deviate from the baseline test conditions, the single-factor correction coefficient for that factor is taken as 1. For example, if the actual measured construction temperature on site is equal to the baseline test temperature, then... and All values ​​are taken as 1; if the initial moisture content of the raw soil measured on site is equal to the reference initial moisture content, then and All values ​​are taken as 1; if the actual measured crushed stone particle content is equal to the benchmark crushed stone particle content, then and All are set to 1. When the experimental results show that the corresponding factor deviates from the baseline experimental conditions but does not require correction, the single-factor correction coefficient for that factor is also set to 1.

[0077] When only one factor in the field operating conditions deviates from the baseline test conditions, the combined operating condition correction factor... and All values ​​are set to 1. At this point, the target water-to-solid ratio and the target curing agent dosage are determined solely by the single-factor correction coefficient corresponding to the deviation factor, without the need for combined operating condition correction.

[0078] Furthermore, the mass of the on-site externally supplied water is determined according to the following relationship: ; In the formula, For the quality of water supplied on site, The dry soil quality of the raw material for the current construction batch. This represents the initial moisture content of the current raw soil. and All calculations are performed using decimals. When the calculated mass of on-site added water is less than 0, the raw soil is subjected to at least one treatment: dehydration, drying, or mixing with similar dry soil, until the existing water mass in the raw soil is not greater than the total water mass determined according to the target water-solid ratio.

[0079] Let the dry soil mass of the current construction batch be... The required mass of curing agent Calculate according to the following formula: ; Total water quality required for the current construction batch Calculate according to the following formula: ; Current water quality in the raw soil Calculate according to the following formula: ; On-site external water quality Calculate according to the following formula: ; Right now: ; In the formula, and All calculations are performed in decimal form.

[0080] When the calculated mass of on-site added water is less than 0, the raw soil is subjected to at least one treatment: dehydration, drying, or mixing with similar dry soil, until the existing water mass in the raw soil is not greater than the total water mass determined according to the target water-solid ratio.

[0081] By deducting the existing water mass in the current raw soil from the target total water mass, the actual total water consumption of the fluidized solidified soil can be matched with the target water-solid ratio, avoiding excessive or insufficient on-site water addition due to fluctuations in the initial moisture content of the raw soil.

[0082] Preferably, the area to be backfilled is a trench backfilling area, a foundation pit backfilling area, a backfilling area around an underground structure, or a roadbed backfilling area.

[0083] To further illustrate the technical solution of the present invention, the following specific embodiments are also provided.

[0084] Example 1 This embodiment uses red sandstone soil from a certain project as the raw material to illustrate the implementation process of the present invention in detail.

[0085] I. Determination of the reference mix proportion: Basic physical properties of raw soil: liquid limit Plastic Limit Natural moisture content =18.6%, maximum dry density .

[0086] Under standard conditions (temperature 25±2℃), the baseline mix proportions were determined as follows through flow spread test and unconfined compressive strength test: Hardener: A composite hardener of cement and mineral powder, wherein cement accounts for 40% and mineral powder accounts for 60%, and the mineral powder is granulated blast furnace slag powder; Lime-to-soil ratio (soldering agent as a percentage of dry soil mass): 10%; Water-to-solid ratio: 0.469; Basalt fiber content: 0.25% (percentage of dry soil mass); Polymer dispersant dosage: 0.1% (percentage of dry soil mass), using polycarboxylate superplasticizer; Under the above-mentioned standard mix proportions, the performance indicators measured under standard conditions are: flow spread 250 mm, density 1.78. The 7-day unconfined compressive strength is 0.92 MPa, and the 28-day unconfined compressive strength is 1.26 MPa.

[0087] II. Establishment of Single-Factor Adjustment Relationships: Based on the benchmark mix proportion, the test temperature, initial moisture content of the raw soil and gravel content were changed respectively, while keeping other conditions unchanged, to prepare single-factor samples and test their performance.

[0088] (1) Temperature factor: At four test temperature levels of 5℃, 25℃, 35℃ and 40℃, while keeping the other mix proportions and preparation conditions unchanged, the initial flow spread, flow spread over time and unconfined compressive strength at the design age of the fluidized solidified soil were tested. The results are shown in Table 1.

[0089] Table 1 Performance test results at different temperatures Table 1 shows that the range of initial flow spread is 45 mm within the temperature range of 5–40 °C. Increased temperature leads to greater loss of flow spread over time. At 40 °C, the flow spread loss over 60 minutes is 90 mm, with a loss rate of approximately 39.1%; at 5 °C, the flow spread loss over 60 minutes is 35 mm, with a loss rate of approximately 12.7%. The 7-day unconfined compressive strength at 40 °C is approximately 26.1% higher than that at 25 °C; the 28-day unconfined compressive strength decreases from 1.26 MPa at 25 °C to 1.20 MPa at 40 °C, a decrease of approximately 4.8%.

[0090] Based on the test results at different temperatures, and using 25 ℃ as the reference test temperature, a polynomial fitting was performed on the water-to-solid ratio temperature correction coefficient to obtain: ; In the formula, This is the temperature correction factor for the water-to-solid ratio. T The test temperature is expressed in °C, and the applicable temperature range is 5–40 °C. T At 25℃, K T Approximately equal to 1.

[0091] The above fitting relationship applies only to the raw soil, curing agent composition, and target construction time used in this embodiment. When the type of raw soil, curing agent composition, or target construction time changes, the temperature correction relationship should be re-determined through testing.

[0092] (2) Initial moisture content factor: Keeping the baseline mix proportion unchanged (water-to-solid ratio fixed at 0.469), the initial moisture content of the raw soil was adjusted to 13.6% ( -5%), 18.6% (benchmark), 23.6% +5%), 28.6% (+10%), the actual amount of water added and strength required to achieve the same flow spread (250±10mm) were tested, and the results are shown in Table 2.

[0093] Table 2 Performance test results at different initial moisture contents As shown in Table 2: (a) An increase in initial moisture content significantly reduces the unconfined compressive strength of solidified soil. When the initial moisture content increases from 13.6% to 28.6%, the 28-day unconfined compressive strength decreases from 1.38 MPa to 0.9 MPa, a decrease of 34.8%.

[0094] (b) The water content correction coefficient is obtained by fitting. The expression is: ; (3) Factors related to the content of crushed stone particles: Keeping the baseline mix proportion unchanged, different proportions of crushed stone particles (particle size 5~20mm) were added to the raw soil, and the changes in flow spread and strength were tested. The results are shown in Table 3.

[0095] Table 3 Performance test results under different crushed stone particle contents As shown in Table 3: (a) Increased gravel content reduces flow spread.

[0096] (b) An increase in the content of crushed stone particles will reduce compressive strength, but the effect is less than that of the initial moisture content.

[0097] (c) As shown in Table 3, the flowability of the solidified soil decreases with increasing crushed stone content. Based on the flowability test results at different crushed stone contents, the flowability retention coefficient of the crushed stone content was obtained by fitting. : ; In the formula, The coefficient for maintaining the fluidity of crushed stone content. This refers to the content of crushed stone particles, expressed as a percentage, with an applicable range of 0% to 50%. As the content of crushed stone particles increases... To compensate for the adverse effects of crushed stone particles on flow spread, the water-to-solid ratio crushed stone content correction factor is reduced. Determined as The reciprocal of, that is: ; When the content of crushed stone particles is 0 =1; When the content of crushed stone particles increases, The corresponding increase is made to improve the target water-to-solid ratio and compensate for the loss of flow spread.

[0098] It should be noted that the above fitting relationship only applies to the raw soil, crushed stone particle size range, and curing agent composition used in this embodiment. When the type of raw soil, crushed stone gradation, or curing agent composition changes, a new crushed stone content correction relationship should be established through experiments.

[0099] III. Application of dynamic adjustment of mix proportions on site: The measured construction temperature at a certain construction site is 35 ℃, the initial moisture content of the raw soil is 23.0%, the crushed stone particle content is 12%, the target construction time is 30 min, and the minimum flow spread over time is 200 mm.

[0100] Step 1: Calculate the correction factors.

[0101] Substituting the construction temperature of 35 ℃ into the temperature correction relationship, we get: ; Substituting the initial moisture content of 23.0% into the moisture content correction relationship, we get: ; When the crushed stone particle content is 12%, the crushed stone content fluidity retention coefficient is: ; The correction factor for water-to-solid ratio and crushed stone content is: ; The on-site operating conditions in this embodiment are within the scope of the combined operating condition test. The water-to-solid ratio combined operating condition correction factor is obtained by referring to tables or interpolation. =1.00.

[0102] Step 2: Calculate the target water-to-solid ratio.

[0103] ; Based on the design age strength verification under corresponding temperature and aggregate content conditions, the temperature correction factor for curing agent dosage was determined. Take 0.98 as the correction factor for the moisture content of the curing agent. Take 1.00 as the correction factor for the curing agent dosage and crushed stone content. Take 1.00 as the correction factor for the combination of curing agent dosage. Take 1.00. Therefore, the target curing agent dosage is: ; Step 3: Calculate the amount of water added on-site.

[0104] Taking the current batch of raw soil with a dry soil mass of 1000 kg as an example, the mass of the curing agent is: ; The total water consumption is: ; The existing water content in the raw soil is: ; The quality of the water supplied on-site is as follows: ; Therefore, the target curing agent mass corresponding to each 1000 kg of raw soil dry soil in this construction batch is 98 kg, and the mass of water added on site is approximately 305.8 kg.

[0105] Step 4: On-site trial mixing and verification.

[0106] Small-volume trial batches of fluidized solidified soil were prepared according to the target water-to-solid ratio of 0.488, the target solidifying agent dosage of 9.8%, and the calculated on-site added water volume. The initial flow spread and the flow spread after 30 minutes were tested.

[0107] Example 2 This embodiment illustrates the application of the present invention under different soil conditions.

[0108] The raw material for a certain project is silty clay with a natural moisture content of [missing information]. =24.5%, with a crushed stone particle content of 22%. The baseline mix proportion is the same as in Example 1.

[0109] Site conditions: Construction temperature 28℃, initial moisture content of raw soil 26.0% (1.5% higher than the benchmark value), and crushed stone particle content 22%.

[0110] Substituting the construction temperature of 28 ℃ into the temperature correction relationship, we get: ; Substituting the initial moisture content of the raw soil (26.0%) into the moisture content correction relationship, we get: ; When the crushed stone particle content is 22%, the crushed stone content fluidity retention coefficient is: ; The correction factor for water-to-solid ratio and crushed stone content is: ; The water-to-solid ratio correction factor for this combined working condition was determined by referring to tables or interpolation. We take 1.00. Therefore, the target water-to-solid ratio is: ; Since the crushed stone particle content exceeds 15%, the correction factor for the curing agent dosage based on the crushed stone content was determined through the design age strength test. The value is 1.08. The construction temperature is 28 ℃, and the temperature correction factor for the curing agent dosage is [not specified]. Take 1.00; Curing agent dosage moisture content correction factor Take 1.00; Correction factor for curing agent dosage combination working conditions Take 1.00. Therefore, the target curing agent dosage is: ; Taking the current batch of raw soil with a dry soil mass of 1000 kg as an example, the mass of the curing agent is: ; The total water consumption is: ; The existing water content in the raw soil is: ; The quality of the water supplied on-site is as follows: ; On-site trial mixing was conducted according to the target water-to-solid ratio of 0.488, the target curing agent dosage of 10.8%, and the calculated amount of water added on-site. The initial flow spread, the flow spread after the target construction time, and the unconfined compressive strength at the design age were tested.

[0111] Example 3 This example illustrates the weighted analysis of the impact of each factor on performance.

[0112] Based on the single-factor test data above, the range comparison method was used to analyze the influence of construction temperature, initial moisture content of raw soil and crushed stone particle content on flow spread and unconfined compressive strength within the range of factors set in this embodiment. The results are shown in Table 4.

[0113] Table 4. Range analysis results of the impact of each factor on performance As shown in Table 4: (1) The control factors for different performance indicators are significantly different. For flow spread, the content of crushed stone particles has the greatest impact (range 65 mm), followed by temperature (45 mm), and the initial moisture content has the least impact (4 mm); for 7-day unconfined compressive strength, temperature has the greatest impact (0.40 MPa), followed by initial moisture content (0.36 MPa), and the content of crushed stone particles has the least impact (0.32 MPa); for 28-day unconfined compressive strength, the initial moisture content has the greatest impact (0.48 MPa), followed by crushed stone particle content (0.42 MPa), and the temperature has the least impact (0.12 MPa).

[0114] (2) The range of temperature on early unconfined compressive strength (7d) (0.40 MPa) is significantly greater than the range of temperature on later unconfined compressive strength (28d) (0.12 MPa). The former is 3.3 times that of the latter, indicating that high temperature has a significant promoting effect on early hydration reaction. However, this accelerating effect has a limited contribution to the increase in strength in the later stage, and the strength growth in the later stage tends to saturate.

[0115] (3) The content of crushed stone particles is the most important factor affecting the flow spread (range 65 mm). Fluctuations in the content of crushed stone particles at the construction site will significantly affect the fluidity of the slurry. The water-solid ratio needs to be adjusted in a timely manner according to the content of crushed stone particles. At the same time, when the content of crushed stone particles exceeds 15%, the amount of curing agent needs to be increased appropriately (increase by 5%~10%) to ensure that the slurry can fully coat the crushed stone particles and ensure the overall strength after curing.

[0116] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A foundation backfilling construction method based on dynamic allocation of fluidized solidified soil under on-site working conditions, characterized in that, Includes the following steps: S1. Under the reference test conditions, prepare fluidized solidified soil samples using raw soil, solidifying agent, and water intended for use in the backfill area, and determine the reference mix proportion that simultaneously satisfies the target initial flow spread, the minimum flow spread over time corresponding to the target construction time, and the unconfined compressive strength at the design age; wherein, the reference test conditions include the reference test temperature, the reference initial moisture content, and the reference crushed stone particle content, and the reference mix proportion includes the reference water-solid ratio and the reference solidifying agent dosage; S2, change one of the following factors: test temperature, initial moisture content of raw soil and crushed stone particle content, while keeping the other factors at the baseline value, and establish a single-factor adjustment relationship; then change at least two of the factors simultaneously to conduct a combined working condition test, and correct the single-factor adjustment relationship based on the combined working condition test results to obtain the working condition adjustment relationship; S3, detect the current construction temperature, the current initial moisture content of the raw soil and the current crushed stone particle content, adjust the benchmark water-solid ratio and the benchmark curing agent dosage according to the working condition adjustment relationship, obtain the target water-solid ratio and the target curing agent dosage, and determine the quality of the on-site external water; S4. Prepare fluidized solidified soil according to the target water-solid ratio, the target solidifying agent dosage and the mass of on-site added water. After the initial flow spread of the fluidized solidified soil meets the target initial flow spread, fill the fluidized solidified soil into the area to be backfilled to form a backfill solidified body that meets the design age unconfined compressive strength.

2. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to claim 1, characterized in that, S1 includes the following steps: S11, the raw soil intended for the backfill area is adjusted to the reference initial moisture content and reference crushed stone particle content, and the adjusted raw soil is placed at the reference test temperature for temperature equilibration; wherein, the crushed stone particle content is the mass percentage of the dry mass of particles with a diameter greater than 5 mm in the raw soil to the dry mass of the raw soil. S12, multiple groups of fluidized solidified soil samples with different water-to-solid ratios and different amounts of solidifying agent were prepared using the adjusted raw soil, solidifying agent, and water; wherein, the amount of solidifying agent was the mass percentage of the solidifying agent to the dry mass of the raw soil. S13, the initial flow spread of each group of fluidized solidified soil samples, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age are tested respectively; the target construction time is the longest time allowed for the fluidized solidified soil from the completion of mixing to entering the backfill area. S14. From the combinations of water-to-solid ratio and curing agent dosage that simultaneously satisfy the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age, select the combination with the lowest curing agent dosage; when the curing agent dosage is the same, select the combination with the lowest water-to-solid ratio, and determine the water-to-solid ratio and curing agent dosage in the selected combination as the reference water-to-solid ratio and reference curing agent dosage, respectively.

3. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to claim 2, characterized in that, S2 includes the following steps: S21. Change one of the following factors: test temperature, initial moisture content of raw soil and crushed stone content, while keeping the other factors at the baseline value, to prepare multiple groups of single-factor samples. S22, the initial flow spread, the flow spread over time after the target construction time, and the unconfined compressive strength after the design age of each group of single-factor samples are detected respectively. By looking up tables, interpolation, or function fitting, the water-solid ratio correction coefficient and the solidifier dosage correction coefficient corresponding to the test temperature, the initial moisture content of the raw soil, and the crushed stone particle content are established respectively as single-factor adjustment relationships. S23, select at least two of the following factors to change simultaneously: test temperature, initial moisture content of raw soil and crushed stone particle content, prepare multiple sets of combined working condition samples, and test the initial flow spread, the flow spread over time after the target construction time and the unconfined compressive strength after the design age of each set of combined working condition samples. S24. Determine the combined working condition correction coefficient based on the test results of the combined working condition sample, and use the combined working condition correction coefficient to correct the single factor adjustment relationship to obtain the working condition adjustment relationship.

4. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to claim 3, characterized in that, S22 includes the following steps: S221, at each test temperature level, prepare multiple sets of samples with different water-to-solid ratios and different curing agent dosages. From the multiple sets of samples, determine the temperature single-factor target mix proportion that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age. Determine the water-to-solid ratio temperature correction coefficient by the ratio of the water-to-solid ratio in the temperature single-factor target mix proportion to the reference water-to-solid ratio, and determine the curing agent dosage temperature correction coefficient by the ratio of the curing agent dosage in the temperature single-factor target mix proportion to the reference curing agent dosage. S222, at each initial moisture content level of raw soil, multiple groups of samples with different water-to-solid ratios and different amounts of curing agent are prepared. From the multiple groups of samples, a single-factor target mix proportion with moisture content that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age is determined. The water-to-solid ratio moisture content correction coefficient is determined by the ratio of the water-to-solid ratio in the single-factor target mix proportion with the reference water-to-solid ratio, and the curing agent content moisture content correction coefficient is determined by the ratio of the curing agent content in the single-factor target mix proportion with the reference curing agent content. S223, at each level of crushed stone particle content, multiple groups of samples with different water-to-solid ratios and different amounts of curing agent were prepared. From these multiple groups of samples, a single-factor target mix proportion for crushed stone content that simultaneously satisfies the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age was determined. The water-to-solid ratio crushed stone content correction coefficient was determined by the ratio of the water-to-solid ratio in the single-factor target mix proportion for crushed stone content to the reference water-to-solid ratio. The curing agent content crushed stone content correction coefficient was determined by the ratio of the amount of curing agent in the single-factor target mix proportion for crushed stone content to the reference amount of curing agent. S224, the correction coefficients for multiple test temperature levels, multiple moisture content levels, and multiple crushed stone particle content levels are fitted to obtain the single-factor adjustment relationship.

5. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to claim 3, characterized in that, The combined operating condition test specimen includes at least one of the following: The test specimen under the first combined working condition was tested with the temperature and initial moisture content of the raw soil changing together, and the crushed stone particle content being maintained at the baseline crushed stone particle content. The second combined working condition sample was tested under conditions in which the test temperature and the content of crushed stone particles changed together, and the initial moisture content of the raw soil was kept at the baseline initial moisture content. The third combination of working conditions was a test sample in which the initial moisture content of the raw soil and the content of crushed stone particles changed together, and the test temperature was kept at the reference test temperature. The fourth combination of working conditions was tested, with variations in test temperature, initial moisture content of raw soil, and gravel particle content.

6. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to claim 3, characterized in that, The combined operating condition correction factor includes the water-to-solid ratio combined operating condition correction factor and the curing agent dosage combined operating condition correction factor; For each combination of working conditions, the predicted water-to-solid ratio and the predicted curing agent dosage are calculated according to the single-factor adjustment relationship. Multiple sets of samples with different water-to-solid ratios and different curing agent dosages are prepared. From the multiple sets of samples, the target mix proportion for the combination of working conditions that simultaneously meets the target initial flow spread, minimum flow spread over time, and unconfined compressive strength at the design age is determined. The water-to-solid ratio combination working condition correction coefficient is the ratio of the measured target water-to-solid ratio to the predicted water-to-solid ratio in the target mix proportion of the combination working condition; The correction coefficient for the curing agent dosage combination working condition is the ratio of the measured target curing agent dosage to the predicted curing agent dosage in the target mix proportion of the combination working condition.

7. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to on-site working conditions as described in claim 6, characterized in that, The target water-to-solid ratio and the target curing agent dosage are determined according to the following relationship: ； ； In the formula, For the target water-to-solid ratio, As the baseline water-to-solid ratio, , and These are the water-to-solid ratio temperature correction factor, water-to-solid ratio moisture content correction factor, and water-to-solid ratio crushed stone content correction factor, respectively. This is the correction factor for the water-to-solid ratio combination working condition; The target curing agent dosage, As a baseline, the amount of curing agent added. , and These are the correction factors for curing agent dosage based on temperature, curing agent dosage based on moisture content, and curing agent dosage based on crushed stone content, respectively. This is a correction factor for the combined working conditions of curing agent dosage. When the corresponding operating conditions do not deviate from the baseline test conditions, or when the test results show that the corresponding factors do not need to be corrected, the corresponding correction factor is taken as 1. When only one factor in the field conditions deviates from the baseline test conditions, the combined working condition correction factor is taken as 1.

8. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to claim 7, characterized in that, The quality of the on-site externally supplied water is determined according to the following relationship: ； In the formula, For the quality of water supplied on site, The dry soil quality of the raw material for the current construction batch. This represents the initial moisture content of the current raw soil. and All calculations are performed using decimals. When the calculated mass of on-site added water is less than 0, the raw soil is subjected to at least one treatment: dehydration, drying, or mixing with similar dry soil, until the existing water mass in the raw soil is not greater than the total water mass determined according to the target water-solid ratio.

9. The foundation backfilling construction method based on dynamically adjusting fluidized solidified soil according to on-site working conditions as described in claim 1, characterized in that, The curing agent is a composite curing agent composed of cement and mineral powder, with the mineral powder accounting for 50% to 70% of the mass of the curing agent.

10. The foundation backfilling construction method based on dynamic allocation of fluidized solidified soil according to any one of claims 1-9, characterized in that, The area to be backfilled is the trench backfilling area, the foundation pit backfilling area, the backfilling area around the underground structure, or the roadbed backfilling area.

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