In-situ treatment technology for expansive soil foundation slope and its stability evaluation method

Abstract

The application discloses an in-situ treatment technology for an expansive soil foundation slope and a stability evaluation method thereof, and relates to the technical field of expansive soil foundation slope performance evaluation.The application is characterized in that an electro-osmosis device and an alkali residue supply device are arranged, and the directional migration of alkali residue in the expansive soil is driven by electric field force to reduce the swelling-shrinkage property; the soil displacement data are obtained by optical measurement, the physical mechanics, swelling characteristics and cation parameters are determined by indoor tests, and a multi-field correlation database of seepage field-mechanical field-chemical field is constructed; a multi-field coupling stability evaluation model is established based on the limit equilibrium theory, the slope safety factor is calculated, and the treatment parameters are dynamically optimized.The application takes alkali residue as a covering layer material, fully utilizes the synergistic effect of the electro-osmosis technology and the covering layer edge wrapping technology, solves the problems of in-situ application difficulty, poor effect and poor durability of the traditional expansive soil treatment technology, and is suitable for the in-situ treatment and stability evaluation of various expansive soil foundation slope projects.

Description

Technical Field

[0001] This invention belongs to the field of in-situ treatment and performance evaluation technology for expansive soil foundation slopes, and in particular relates to an in-situ treatment technology for expansive soil foundation slopes and its stability evaluation method. Background Technology

[0002] Expansive soil foundation slopes are very common in engineering construction. Due to the special composition of the soil, it easily expands when exposed to water and shrinks when dehydrated, forming many irregular cracks within the soil. The presence of these cracks disrupts the integrity of the soil and creates channels for water infiltration. Under rainfall conditions, water seeps into the soil through these cracks, causing the soil to soften and weaken, leading to instability and collapse, and posing a serious threat to the safety of surrounding buildings and the normal progress of the project.

[0003] Currently, there is an increasingly urgent need for the treatment of expansive soil foundation slopes in engineering projects. It is necessary to achieve in-situ treatment to reduce interference with the surrounding environment, reduce engineering costs and improve treatment efficiency, and accurately assess the stability after treatment to ensure that the slope remains stable in the long term.

[0004] Existing technologies have significant shortcomings in in-situ treatment and stability assessment of expansive soil foundation slopes. On the one hand, existing treatment methods, such as non-expansive clay covering technology and improved soil covering technology, mostly use lime and cement mixtures as edging soil layers, which generally suffer from: ① uneven on-site mixing and low construction efficiency; ② inability to perform in-situ treatment; ③ poor economic benefits when used on a large scale. Geotextile bag technology and reinforced backfilling technology also suffer from complex construction processes and high costs, resulting in poor applicability. More importantly, these technologies are all based on the principles of "seepage prevention and moisture retention" and "counter-pressure swelling reduction," failing to fundamentally solve the swelling and shrinkage problem of expansive soil. Once the protective layer fails, all previous efforts are wasted.

[0005] On the other hand, existing stability assessment methods have limitations in the data collection and analysis stages. They either rely on a single measurement method to obtain data, resulting in insufficient data comprehensiveness and accuracy, or fail to highlight the core role of the chemical field (cation type and concentration) in stability analysis and fail to establish the multi-field coupling relationship between the seepage field, mechanical field, and chemical field. This leads to deviations between the assessment results and the actual slope stability state, and cannot provide a reliable reference for whether further treatment of the slope is needed.

[0006] Against this backdrop, exploring efficient and reliable synergistic treatment and stability assessment methods has become an important research direction in the field of engineering technology. A stability assessment method for expansive soil foundation slopes based on electroosmosis-alkali slag synergistic in-situ treatment has emerged, aiming to utilize the rich... Using alkali slag containing calcium salts as a capping material, combined with electroosmosis treatment technology, a synergistic treatment effect of modifying shallow expansive soil and inhibiting deep expansive soil is achieved. A multi-field coupled scientific evaluation process is established to determine slope stability. On the one hand, the electric field applied through electroosmosis is used to directionally regulate the calcium salts in the alkali slag. The migration of ions into expansive soil generates ion exchange and cementation, achieving in-situ modification of shallow expansive soil and fundamentally solving the swelling and shrinkage problem. Simultaneously, the presence of the alkali slag layer also serves to "prevent seepage and retain moisture" and "reverse pressure and reduce swelling," further enhancing the treatment effect. Furthermore, the alkali slag naturally has a high water content and is alkaline, which not only facilitates the on-site implementation of electroosmosis but also effectively solves the problem of excessive energy consumption in existing electroosmosis technologies, while avoiding environmental pollution from alkaline leachate. This invention offers excellent technical performance, durability, stability, low cost, and convenient and efficient construction. Summary of the Invention

[0007] The purpose of this invention is to provide an in-situ treatment technology for expansive soil foundation slopes and a stability assessment method thereof, which uses an electric field to drive alkaline slag... Targeted migration enables in-situ modification of shallow expansive soil, fundamentally weakening its swelling and shrinkage characteristics and solving the problems of difficulty in in-situ application, poor effect, and poor durability of existing expansive soil treatment technologies.

[0008] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0009] This invention relates to an in-situ treatment technology for expansive soil foundation slopes and a method for assessing their stability, comprising the following steps:

[0010] Step S1: Select the area to be treated on the expansive soil foundation slope, and install an electroosmosis device and an alkali residue supply device; wherein, the electroosmosis device includes multiple anode electrodes and cathode electrodes, which are alternately arranged at a preset interval at the boundary of the area to be treated; the alkali residue supply device includes a storage tank and a conveying pipeline, with the pipeline outlet located at the surface or shallow layer of the area to be treated, for providing a solution containing... Alkali residue slurry;

[0011] Step S2: Start the electroosmosis device and apply a DC electric field to the area to be treated, using the electric field force to drive the alkaline residue slurry... The process involves migrating the slurry towards the expansive soil to replace the low-valence cations adsorbed in the soil; simultaneously, the supply rate of the alkaline slurry is controlled to form a slurry covering layer on the surface of the area to be treated, and the operation is suspended after a preset duration.

[0012] Step S3: Use an optical measuring device to perform linear dimension measurement of the area to be treated, obtain the lateral displacement and longitudinal compression of the expansive soil at different depths, and collect expansive soil samples at different locations within the area to be treated.

[0013] Step S4: Perform physical and mechanical property tests on the collected expansive soil samples to obtain parameters such as moisture content, dry density, cohesion, and internal friction angle; test the expansive soil's swelling characteristics, including swelling force and swelling rate; test the expansive soil's swelling deformation and swelling force parameters under different cation types and concentrations; and construct a multi-field correlation database of expansive soil deformation and seepage field, mechanical field, and chemical field by combining displacement data obtained from optical measurements.

[0014] Step S5: Based on a multi-field correlation database, a preset algorithm is used to analyze the stability of the expansive soil foundation slope after electro-osmosis-alkali slag co-treatment and calculate the safety factor of the slope. The algorithm establishes a slope stability assessment model coupled with seepage field, mechanical field and chemical field by calling displacement, mechanical field and chemical field parameters at different depths and locations in the database and performs inversion calculation.

[0015] Step S6: Based on a multi-field correlation database, combined with real-time monitoring data of deformation, water content, stress, and ion concentration of expansive soil at different depths and directions, the modification effect of the shallow expansive soil in the area to be treated is verified through inversion calculation, and the determination is made. Check whether the migration depth, ion exchange degree, and reduction in expansibility meet the preset technical requirements; if not, adjust the electric field strength of the electroosmosis device, the alkaline slurry supply rate, or the slurry concentration, and repeat S2 to S5 until the shallow expansive soil modification effect meets the standard.

[0016] As a preferred technical solution, the following model formula is used to control the injection flow rate of the alkaline residue slurry in step S2: ;in, Indicates the injection flow rate of alkaline residue slurry. This represents the permeability coefficient of expansive soil. This represents the total cross-sectional area of ​​the injection hole. This represents the difference between the injection pressure and the internal pressure of the area to be treated. Indicates the dynamic viscosity of the alkaline residue slurry. This represents the average distance from the injection hole to the boundary of the area to be treated. Indicates the flow attenuation coefficient. Indicates the injection time.

[0017] As a preferred technical solution, step S2 includes the following steps:

[0018] Step S21: Check the connection status of the anode and cathode electrodes of the electroosmosis device to ensure that the circuit between the electrodes and the DC power supply is conductive. Use a multimeter to measure the initial resistance value between the electrodes and record the measurement data.

[0019] Step S22: Check the sealing of the storage tank and conveying pipeline of the alkali residue supply device. Pour the alkali residue slurry into the storage tank, start the conveying pump, and let the slurry circulate in the pipeline for a preset time. Observe whether there is any slurry leakage at the pipeline connection. At the same time, confirm that the slurry concentration is uniform and there is no obvious sedimentation.

[0020] Step S23: Based on the characteristics of the expansive soil in the area to be treated, set the initial intensity of the DC electric field and the initial supply rate of the alkali slag slurry; input the set parameters into the control terminal, and send the start command to the electroosmosis device and the alkali slag supply device to ensure that the slurry forms a uniform covering layer on the surface of the area to be treated.

[0021] Step S24: During the electroosmosis and alkali slag supply process, at preset time intervals, the electric field strength and slurry supply rate data are collected through the control terminal; at the same time, observe whether there are any abnormal phenomena such as bulging or cracks on the surface of the area to be treated, and record the abnormal data.

[0022] As a preferred technical solution, step S3 includes the following sub-steps:

[0023] Step S31: Divide the surface of the area to be treated into multiple measurement sub-regions. Set no less than three optical measurement markers in each sub-region to ensure that the markers are within the field of view of the optical measurement device. Adjust the focal length and angle of the measurement device to make the markers clear.

[0024] Step S32: Start the optical measurement device to continuously photograph the marker points in each sub-region, acquire image data at different time points, use image analysis software to extract the coordinate information of the marker points, and calculate the coordinate changes of the marker points at adjacent time points.

[0025] Step S33: Use drilling equipment to drill test holes at different locations in the area to be treated, insert optical measuring probes into the test holes at different depths, measure the changes in the transverse and longitudinal dimensions of the expansive soil at each depth, and record the measurement data at each depth.

[0026] Step S34: Collect expansive soil samples at different locations in the area to be treated using the ring cutter method. Collect at least three parallel samples at each collection location. Place the samples in a sealed container, label the collection location and depth information, and send them to the laboratory for subsequent testing.

[0027] As a preferred technical solution, in step S3, the following model formula is used to calculate the lateral displacement of the expansive soil: ,in, This indicates the lateral displacement of expansive soil. Indicates the magnification factor of the optical measuring device. This represents the change in length of a reference line segment in optical measurements. This indicates the vertical distance from the measurement point to the baseline. This represents the strain of expansive soil in the x-direction. This represents the strain of expansive soil in the y-direction.

[0028] As a preferred technical solution, step S4 includes the following sub-steps:

[0029] Step S41: Place the collected expansive soil sample in a constant temperature and humidity environment. After the sample condition stabilizes, use a balance to measure the wet mass of the sample. Then put the sample into an oven and dry it at a preset temperature until constant weight. Measure the dry mass of the sample and calculate the sample moisture content.

[0030] Step S42: Take the dried sample, measure the relative density of the solid particles using the specific gravity bottle method, measure the total volume of the sample using a volume analyzer, and calculate the dry density of the sample by combining the dry mass data.

[0031] Step S43: Prepare standard specimens from some expansive soil samples, place them in a triaxial shear apparatus, apply different confining pressures to conduct shear tests, record the stress and strain data during the test, and obtain the cohesion and internal friction angle of the specimens through data fitting.

[0032] Step S44: Use a dilatometer to test the expansion force and expansion rate of the sample, obtain expansion characteristic parameters, and use an ion electrode to detect the cation type and concentration of different samples to test the expansion deformation data under different cation conditions.

[0033] Step S45: Associate all the moisture content, dry density, cohesion, internal friction angle, expansion characteristics, and cation parameters obtained from the tests with the corresponding collection location, depth information, and displacement data, and enter them into the computer database to establish a multi-field association database indexed by "location-depth-multi-field parameters".

[0034] As a preferred technical solution, in step S44, the following model formula is used to obtain the dry density of expansive soil: ,in, This indicates the dry density of expansive soil. This indicates the mass of solid particles in the expansive soil sample. This represents the total volume of the expansive soil sample. This indicates the moisture content of the expansive soil sample.

[0035] As a preferred technical solution, step S5 includes the following sub-steps:

[0036] Step S51: Extract displacement data, mechanical parameters and chemical field parameters of expansive soil at different depths and locations in the area to be treated from the associated database, divide the data into multiple calculation units according to spatial coordinates, and determine the boundary range and average value of each parameter of each calculation unit.

[0037] Step S52: Input the parameters of each calculation unit into the preset algorithm to construct the geometric model of the slope and the mechanical model coupled with the seepage field-mechanical field-chemical field. Set the boundary conditions and load conditions of the model. The boundary conditions include the constraints of the top, bottom and sides of the slope, and the load conditions include the self-weight of the expansive soil and the external additional load.

[0038] Step S53: Run the algorithm to calculate the model, obtain the stress distribution and strain distribution data of each calculation unit in the slope, combine the influence of cation concentration change on expansibility, determine the location and shape of the potential sliding surface, and calculate the anti-sliding force and sliding force on the sliding surface.

[0039] Step S54: Based on the calculation results of anti-sliding force and sliding force, determine the safety factor of the slope, and at the same time generate stress and strain distribution cloud maps and sliding surface schematic diagrams, and store the calculation results and graphic data in the database.

[0040] As a preferred technical solution, in step S53, based on the actual dimensions of the slope, a two-dimensional geometric model is established in the finite element analysis software. The model height is 10m, the horizontal length at the slope toe is 20m, and the slope ratio is 1:2. The calculation units correspond one-to-one with the 50 grids previously divided. The seepage field-mechanical field-chemical field coupling algorithm is selected, and the cation concentration is used as the core parameter of the chemical field. The correlation function between concentration and soil cohesion and internal friction angle; the higher the concentration, the higher the mechanical parameter correction factor. The larger.

[0041] As a preferred technical solution, in step S54, the safety factor of the slope is calculated using the following model formula: ;in, Indicates the slope safety factor. Indicates the first The cohesion of expansive soil in each calculation unit. Indicates the first The normal stress on the expansive soil in each calculation unit Indicates the first The internal friction angle of expansive soil in each calculation unit. Indicates the first The length of the sliding surface of each computational unit. This indicates the unit weight of expansive soil. Indicates the first The slope height corresponding to each calculation unit Indicates the dip angle of the slope sliding surface. This indicates the total number of computing units.

[0042] As a preferred technical solution, the specific implementation process of step S6 is as follows:

[0043] Step S61: Real-time monitoring data and multi-site database data linkage retrieval: Extract real-time monitoring data of the area to be treated from the engineering monitoring terminal, establish data index according to depth layering and spatial location, and retrieve the basic calibration data of the expansive soil from the multi-site related database. Match the real-time monitoring data with the basic calibration data of the database according to depth, location and index.

[0044] Step S62: Quantitative analysis of core indicators of modification effect based on inversion calculation: The modification effect is fitted through inversion calculation. The concentration variation curve with soil depth is used as the design critical concentration for modification to determine the soil depth corresponding to the threshold in the curve. Based on the cationic composition of each depth layer obtained by inversion calculation, and combined with the correlation model of cationic composition and expansibility parameters in the database, the expansibility force and free expansibility of each depth layer after treatment are calculated. Then, compared with the initial value before treatment, the reduction rate of expansibility force and the reduction rate of expansibility are obtained.

[0045] Step S63: Benchmarking the Modification Effect against the Preset Technical Requirements: The actual values ​​of the indicators obtained from the inversion calculation are compared with the preset technical requirements for the modification of shallow expansive soil in the project. Only when all depth layers meet the preset requirements can the modification effect be judged to be up to standard. If any layer or a core indicator is not met, the modification effect is judged to be down to standard, and the parameter adjustment stage is entered.

[0046] Step S64, Targeted adjustment of treatment parameters in case of non-compliance: Based on the type and degree of deviation of the non-compliance indicators, the three core parameters of the electroosmosis device, the electric field strength, the alkaline slurry supply rate, and the alkaline slurry concentration are adjusted in a targeted manner, and the adjustment range is set according to the degree of deviation.

[0047] Step S65, Secondary Verification of Treatment and Modification Effects: Restart the electroosmosis unit and alkali residue supply unit according to the adjusted parameters, and repeat steps S2, S3, S4, and S5. Adjust the operation time appropriately according to the degree of deviation. After completing the repeated operation, follow this process again. The steps involve a second verification of the modification effect of shallow expansive soil. If the second verification meets the standards, the modification effect verification stage ends and the overall slope stability assessment stage begins. If the standards are still not met, the parameters are optimized again according to the principle of step S64 until the modification effect fully meets the preset technical requirements.

[0048] The present invention has the following beneficial effects:

[0049] (1) This invention abandons the traditional passive protection approach of "seepage prevention and moisture retention" and "reverse pressure to reduce expansion", and uses an electroosmotic electric field to drive the alkaline residue in The material is directed to the interior of the expansive soil, and in-situ modification of the shallow expansive soil is achieved through ion exchange and cementation. This changes the ionic environment of the expansive soil at the microscopic level and reduces the swelling and shrinkage of the soil from the root. At the same time, the alkali slag cover layer forms a passive protection, achieving the dual effect of active modification and passive protection. This solves the pain point of treatment failure when the protective layer fails in traditional technology, and the treatment effect is more durable and stable.

[0050] (2) This invention utilizes the synergistic effect of electroosmosis and alkaline residue. The alkaline residue is rich in calcium salts and has a high natural water content and is alkaline, which provides sufficient conditions for ion migration. The source was optimized, and the soil environment for electroosmosis operations was improved, significantly enhancing... The efficiency of migration and replacement is improved; at the same time, the alkaline properties of the alkali residue are suitable for electroosmosis technology, which effectively reduces the energy consumption of electroosmosis operations. Moreover, as a low-cost and environmentally friendly material, the alkali residue can replace traditional lime and cement mixing treatment, avoid the problem of uneven mixing on site, greatly reduce the cost of engineering materials and construction, and improve the efficiency of in-situ treatment.

[0051] (3) This invention constructs a multi-field correlation database that integrates seepage field, mechanical field and chemical field, and incorporates the core chemical index of cation type and concentration into the stability assessment system, breaking through the limitations of traditional assessment that relies solely on mechanical and displacement data; at the same time, it establishes a two-layer judgment logic from treatment effect verification to slope stability assessment, first verifying the slope safety factor, and then verifying the treatment effect, so that the assessment results are highly consistent with the actual soil modification state and slope stability state, providing a more reliable reference for engineering decision-making.

[0052] (4) The present invention adopts an in-situ treatment mode, which does not require complicated mixing and backfilling processes. The operation can be completed simply by setting up an electroosmosis device and an alkali slag supply device, forming an alkali slag covering layer on the slope surface and applying a DC electric field. The construction process is simple and avoids the problems of complicated construction of geotextile bags, reinforced back wrapping and other technologies. It has little interference with the surrounding environment. At the same time, the electric field strength, slurry supply rate and other parameters can be dynamically adjusted according to the soil modification effect and the slope stability judgment results. The operation is highly flexible and adaptable to expansive soil foundation slope engineering with different geological conditions.

[0053] (5) This invention uses alkaline slag as the core treatment material, realizing the resource utilization of industrial waste residue. The alkaline leachate in the alkaline slag will be neutralized in the electrode reaction of electroosmosis, effectively avoiding pollution to the surrounding soil and water bodies, and solving the environmental hazards of alkaline treatment materials. At the same time, the technical solution does not require large construction equipment and simplifies the on-site operation process. It not only meets the project's needs for in-situ treatment and efficient construction, but also conforms to the industry development trend of green construction and waste residue resource utilization. It combines industrial practicality and environmental friendliness.

[0054] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments 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 these drawings without creative effort.

[0056] Figure 1 This is a flowchart of an in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to the present invention. Detailed Implementation

[0057] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figure 1 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0060] Please see Figure 1 As shown, this invention provides an in-situ treatment technology and stability assessment method for expansive soil foundation slopes, comprising the following steps:

[0061] Step S1: Select the area to be treated on the expansive soil foundation slope, and install an electroosmosis device and an alkali residue supply device; wherein, the electroosmosis device includes multiple anode electrodes and cathode electrodes, which are alternately arranged at a preset interval at the boundary of the area to be treated; the alkali residue supply device includes a storage tank and a conveying pipeline, with the pipeline outlet located at the surface or shallow layer of the area to be treated, for providing a solution containing... Alkali residue slurry;

[0062] Specifically, the process involves precise site selection for the treatment area and standardized deployment of electroosmosis and alkali residue supply devices, which is divided into four stages:

[0063] Phase 1: Survey and Selection of Areas to be Treated

[0064] Conduct geological surveys to determine core indicators such as slope gradient, height, and soil composition, and clarify the montmorillonite content, initial cation type, moisture content, and swelling characteristic parameters of the expansive soil; delineate the boundaries of the area to be treated, avoiding obstacles such as underground pipelines and structures, and ensure that the uniformity of the soil in the area meets the treatment requirements; mark the boundary lines and key control points of the area to provide positioning benchmarks for the deployment of equipment.

[0065] Phase Two: Electroosmosis Device Installation Phase

[0066] Determine the electrode specifications, select the electrode length according to the slope height, and use metal material with an electrode diameter of 20mm-30mm; mark the boundary of the area to be treated according to the preset spacing, and arrange the anode and cathode electrodes alternately; use drilling equipment to vertically insert the electrodes into the soil, control the insertion depth, and ensure that the part of the electrode exposed above the ground is used for wiring; connect the electrodes to the DC power supply control cabinet, use a multimeter to test the conductivity and initial resistance value between the electrodes, and record the data.

[0067] Phase Three: Layout of Alkali Sludge Supply Unit

[0068] Determine the location of the storage tank; the site should be close to the area to be treated and on flat terrain to facilitate slurry transportation. Lay the delivery pipeline, using polyethylene pipes with a diameter of 20mm-30mm. The pipeline outlet should be located at the surface of the area to be treated or at a depth of 0.2m-0.5m. Install pipeline valves and flow controllers, connect the storage tank and the delivery pump, and check the pipeline's sealing performance. Configure [equipment / facilities]. The alkaline slurry ensures The concentration meets the design requirements, and the slurry is injected into the storage tank.

[0069] Phase Three: Equipment Commissioning and Acceptance

[0070] Trial run the DC power supply control cabinet to confirm that the electric field strength adjustment function is normal, start the delivery pump, and test the slurry supply rate and pipeline unobstructedness. If there is no leakage, the installation is complete.

[0071] In practice, a 50m long and 10m wide area on the lower part of the slope to be treated was selected as the treatment area. This area avoided the drainage ditch at the toe of the slope and underground communication pipelines. The boundaries of the area were marked using a total station, and 10 control points were set to ensure accurate area measurement. Galvanized steel pipes with a diameter of 25mm and a length of 7m were used as anode and cathode electrodes for the electroosmosis device. Lines were laid out at a preset interval of 1.0m along the boundary of the treatment area, with anode and cathode electrodes arranged alternately, for a total of 60 electrodes. Holes were drilled using a drilling machine, and the electrodes were vertically inserted into the soil for 5m, with 2m protruding above the ground for connecting the lines. All electrodes were connected to the DC power supply control cabinet, and the initial resistance between the electrodes was measured using a multimeter. The measured resistance range was 8Ω-15Ω, which meets the normal standard of 5Ω-20Ω.

[0072] When supplying alkali residue, a 150L corrosion-resistant storage tank is placed at a level location on the top of the slope, 3m away from the boundary of the area to be treated; a 25mm diameter polyethylene delivery pipeline is laid, with the pipeline outlet buried 0.3m below the surface of the area to be treated, with a total of 5 outlets evenly distributed within the area; an electromagnetic flow controller and ball valve are installed, connecting the storage tank and the variable frequency delivery pump; and a configuration is made. A 0.6 mol / L alkaline residue slurry is prepared by mixing 1000 kg of alkaline residue with water and stirring until homogeneous, then injecting the mixture into a storage tank.

[0073] During device commissioning, the DC power supply control cabinet was turned on, and the electric field strength was adjusted to 2.5V / cm. The current between the electrodes stabilized at around 10A, with no short circuit. The delivery pump was started, and the slurry supply rate was set to 1.0L / min. After running for 30 minutes, there was no slurry leakage at the pipe connections, and the slurry output from each outlet was uniform.

[0074] Step S2: Start the electroosmosis device and apply a DC electric field to the area to be treated, using the electric field force to drive the alkaline residue slurry... Migrate to expansive soil; at the same time, control the supply rate of alkaline slurry to form a slurry covering layer on the surface of the area to be treated, and stop the operation after a preset time.

[0075] Specifically, after setting the parameters according to the device deployed in step S1, the device is started: based on the characteristic of the expansive soil in this area having a moisture content of 30%, the initial intensity of the DC electric field is set to 2.5V / cm, and the current is controlled within the range of 8A-12A through the DC power supply control cabinet to avoid excessive current causing electrode overheating; combined with the area to be treated The area is set, and the alkali residue slurry supply rate is set to 1.0L / min to ensure that the slurry can form a uniform covering layer with a thickness of more than 10cm on the soil surface to prevent external water from seeping in; the electric field strength and slurry supply rate parameters are input into the control terminal, and a start command is sent to simultaneously start the electro-osmosis device and the alkali residue supply device.

[0076] The coordinated treatment was set to last 48 hours. During the operation, data on electric field strength and slurry supply rate were collected every hour via the control terminal to ensure that the electric field strength remained stable at 2.5V / cm ± 0.5V / cm and the supply rate remained stable at 1.0L / min ± 0.1L / min. A designated person inspected the surface of the area to be treated every 2 hours to observe for any abnormalities such as bulging or cracks. During the inspection, a minor crack measuring 2cm in length and 0.5mm in width was found in a localized area of ​​the slope. This crack did not exceed the warning threshold of 5cm in length and 2mm in width. The coordinates and crack size were recorded, and the operation continued. After 48 hours, the delivery pump of the alkali residue supply device was shut off to stop the slurry supply. After the residual slurry in the pipeline flowed back to the storage tank, the DC power supply to the electroosmosis device was cut off, completing this round of coordinated treatment and proceeding to the subsequent displacement measurement and sample collection phase.

[0077] Step S3: Use an optical measuring device to perform linear dimension measurement of the area to be treated, obtain the lateral displacement and longitudinal compression of the expansive soil at different depths, and collect expansive soil samples at different locations within the area to be treated.

[0078] Specifically, taking the subsequent testing phase of a highway expansive soil foundation slope project as an example, 48 hours after step S2 (electro-osmosis-alkali slag synergistic treatment), displacement measurement and sample collection were carried out on the slope, covering an area of ​​200 square meters. The slope height is 10m and the slope ratio is 1:2. The specific implementation process is as follows:

[0079] The measurement area was divided into 50 measurement sub-areas with a grid spacing of 2m×2m. One optical measurement marker was set at the center and four corners of each sub-area. The markers were made of circular reflective metal sheets with a diameter of 15mm, which were pasted on flat and crack-free areas of the slope surface. A total of 250 markers were set up. A laser displacement sensor with an accuracy of 0.01mm was selected as the optical measurement device. The sensor was installed at a height of 3m, with the emission angle perpendicular to the slope surface and the focal length adjusted to 1m to ensure that all markers were within the sensor's field of view and that the images were clear.

[0080] Surface displacement data acquisition and calculation: The laser displacement sensor was activated, and the shooting interval was set to 15 minutes. Image data of each marker point was continuously acquired over 4 hours, resulting in 17 sets of time-series images. Image analysis software was used to extract the three-dimensional coordinate information of each marker point, and the coordinate changes of the marker points at adjacent time points were calculated. Data processing showed that the lateral displacement of the slope surface soil ranged from 0.2mm to 0.8mm, and the longitudinal compression ranged from 0.1mm to 0.4mm. The area with the largest displacement was concentrated in the middle and lower part of the slope (at a depth of 2m-3m).

[0081] Displacement measurements at different depths were performed using a geological drilling machine with an 80mm borehole diameter. Ten typical locations in the area to be treated were selected using a grid method to drill test holes, with a drilling depth of 3m, covering the top, middle, lower and toe areas of the slope.

[0082] A portable optical measuring probe with a diameter of 20mm was inserted into the test hole, and the lateral and longitudinal dimensional changes of the soil at depths of 0.5m, 1m, 1.5m, 2m, 2.5m, and 3m were measured at 0.5m depth intervals. The measurement records showed that at depths of 0.5m-1m, the lateral displacement was 0.5mm-1.0mm, and the longitudinal compression was 0.2mm-0.5mm; at depths of 2.5m-3m, the lateral displacement decreased to 0.1mm-0.3mm, and the longitudinal compression decreased to 0.05mm-0.2mm, indicating that the displacement of the deeper soil layers was significantly less than that of the surface layer.

[0083] Using a ring cutter with an inner diameter of 100 mm and a height of 150 mm, three parallel sampling points were selected around each of the 10 test holes. The sampling depth corresponded one-to-one with the displacement measurement depth (0.5 m, 1 m, 1.5 m, 2 m, 2.5 m, 3 m), and a total of 180 expansive soil samples were collected.

[0084] Avoid disturbing the soil during the collection process. After each sample is collected, it should be immediately placed in a sealed plastic bag, and the sampling location coordinates, depth and collection time should be marked. The sample should be sent to the laboratory for storage in a constant temperature and humidity environment (23℃±2℃, relative humidity 50%±5%) within 2 hours, awaiting subsequent physical and mechanical property testing.

[0085] Step S4: Perform physical and mechanical property tests on the collected expansive soil samples to obtain parameters such as moisture content, dry density, cohesion, and internal friction angle; test the expansive soil's swelling characteristics, including swelling force and swelling rate; test the expansive soil's swelling deformation and swelling force parameters under different cation types and concentrations; and construct a multi-field correlation database of expansive soil deformation and seepage field, mechanical field, and chemical field by combining displacement data obtained from optical measurements.

[0086] Specifically, taking the laboratory testing phase of an expansive soil foundation slope project for a highway as an example, this phase, based on 180 expansive soil samples collected in step S3 (covering six depths: 0.5m, 1m, 1.5m, 2m, 2.5m, and 3m, with 30 samples at each depth), conducts tests on physical and mechanical properties, expansive characteristics, and the influence of cations. Finally, a multi-field correlation database is constructed. The specific implementation process is as follows:

[0087] 1. Moisture content test: The collected expansive soil samples were placed in a constant temperature and humidity chamber, with the temperature set at 23℃±2℃ and the relative humidity at 50%±5%, and left to stand for 24 hours until the state stabilized. The wet mass of the sample was measured using an electronic balance with an accuracy of 0.001g. Then, the sample was dried in an oven at 105℃±5℃ for 24 hours until constant weight was achieved. After cooling, the dry mass was measured. The calculation showed that the soil moisture content after treatment ranged from 18% to 22%, which was significantly lower than the 30% before treatment. The moisture content in the deeper layers (2.5m-3m) was slightly lower than that in the surface layer (0.5m-1m).

[0088] 2. Dry density test: Take the dried sample and measure the relative density of solid particles using the specific gravity bottle method. The average relative density of the expansive soil particles is measured to be [value missing]. Use a volume analyzer to measure the total volume of the sample inside the ring cutter (ring cutter volume). Based on the dry mass data, the dry density was calculated, and the results showed that the dry density of the treated soil ranged from [value missing]. Meeting the engineering requirements The standard is met, and the dry density increases slightly with depth.

[0089] 3. Cohesion and internal friction angle tests: Representative samples from each depth were selected and standard triaxial specimens with a diameter of 39.1 mm and a height of 80 mm were prepared. The specimens were placed in a triaxial shear apparatus, and confining pressures of 50 kPa, 100 kPa, and 150 kPa were applied respectively. Shear tests were conducted at a strain rate of 0.02 mm / min, and stress-strain data were recorded. Through Mohr-Coulomb strength curve fitting, it was found that the cohesion of the treated soil ranged from 20 kPa to 30 kPa, and the internal friction angle ranged from 18° to 22°. Compared with before treatment, the cohesion increased by about 40%, and the internal friction angle increased by about 25%.

[0090] 4. Expansion Characteristic Parameter Testing: A consolidation dilatometer was used to test the free expansion rate and expansion force of samples at various depths. Test conditions: The samples were dried, crushed, and passed through a 0.5mm sieve. Water was added to saturate the samples under a pressure of 50 kPa. The height change and pressure value were recorded after the expansion stabilized. Results: After treatment, the free expansion rate of the soil decreased to 25%-35%, and the expansion force decreased to 30 kPa-50 kPa, a reduction of more than 50% compared to before treatment. The higher the concentration of the sample, the lower the expansion characteristic parameter.

[0091] 5. Test on the Influence of Cation Type and Concentration: The ion-selective electrode method was used to test the cation exchange capacity (CEC) of the soil. This test was used to determine the degree of ion exchange between Ca and expansive soil. The results showed that the soil after treatment... The concentration was increased to 0.4 mol / L-0.6 mol / L, achieving effective replacement of low-valent cations. Samples with different cation concentrations were selected ( Indoor expansion and deformation comparison tests were conducted at concentrations of 0.2 mol / L, 0.4 mol / L, and 0.6 mol / L.

[0092] Experiments show that: For every 0.2 mol / L increase in concentration, the soil swelling rate decreased by about 12% and the swelling force decreased by about 15%, verifying the decisive influence of cation type and concentration on the properties of expansive soil.

[0093] 6. Construction of multi-field relational databases

[0094] A database index structure was established: using sampling location coordinates-depth as the primary index, and linking seepage field parameters (water content), mechanical field parameters (dry density, cohesion, internal friction angle), and chemical field parameters (cation type and concentration, expansion characteristic parameters). The displacement data (lateral displacement, longitudinal compression) obtained in step S3 was imported and bound to the corresponding multi-field parameters to clarify the correlation between "increased cation concentration → decreased expansion characteristics → decreased soil displacement." The database uses both Excel and SQL formats for storage, supporting rapid retrieval by depth and parameter type, providing complete data support for the subsequent multi-field coupled stability analysis in step S5.

[0095] Through system testing and database construction, the mechanism by which electro-osmosis-alkali slag synergistic treatment improves the performance of expansive soil was clarified, and the role of chemical field (cations) as a core influencing factor was verified, providing a precise data foundation for slope stability assessment.

[0096] Step S5: Based on a multi-field correlation database, a preset algorithm is used to analyze the stability of the expansive soil foundation slope after electro-osmosis-alkali slag co-treatment and calculate the safety factor of the slope. The algorithm establishes a slope stability assessment model coupled with seepage field, mechanical field and chemical field by calling displacement, mechanical field and chemical field parameters at different depths and locations in the database and performs inversion calculation.

[0097] Specifically, taking the stability analysis stage of a highway expansive soil foundation slope project as an example, after step S2 collaborative treatment, step S3 displacement measurement, and step S4 multi-field parameter testing, stability analysis was carried out based on the constructed multi-field correlation database. The slope height is 10m, the slope ratio is 1:2, and the area to be treated is [area missing]. The specific implementation process is as follows:

[0098] Core data was extracted from a multi-field correlation database: soil moisture content (18%-22%) and dry density ( ) at six depths: 0.5m, 1m, 1.5m, 2m, 2.5m, and 3m. ), cohesion ( ), internal friction angle ( ), cation concentration ( 0.4 mol / L-0.6 mol / L) and displacement data (lateral displacement of the surface layer 0.2 mm-0.8 mm, and the deep layer 0.1 mm-0.3 mm).

[0099] The entire slope was divided into 15 calculation units using a 2m × 2m spatial grid. Each unit corresponds to the average parameter values ​​for a specific depth range. For example, the average parameters for the lower part of the slope (depth 2m-3m) are: moisture content 19%, dry density 1.82g / cm³, cohesion 28kPa, and internal friction angle 21°. Concentration 0.55 mol / L.

[0100] When calculating stress and strain and identifying potential sliding surfaces, the corrected parameters of each calculation unit are input into the model, and the algorithm is run to perform inversion calculations to obtain the stress and strain distribution data of each unit in the slope.

[0101] Calculation results show that the shear stress is highest in the lower part of the slope element, reaching a maximum of 42 kPa, but this does not exceed the corrected shear strength of the soil. The stress concentration area is mainly distributed at a depth of 1.5 m to 2.5 m, consistent with the displacement-sensitive area measured in step S3. Five potential sliding surfaces were identified through stress abrupt change characteristics, with sliding surface dip angles α ranging from [value missing]. Length of sliding surface The range is 8m-12m.

[0102] The safety factor for each potential sliding surface is calculated using the safety factor formula:

[0103] ;

[0104] Calculations showed that the safety factors for the five potential sliding surfaces were 1.32, 1.35, 1.28, 1.30, and 1.29, respectively. The minimum value of 1.28 was taken as the final safety factor for the slope. Visualization results were generated: a slope stress distribution cloud map, a strain distribution cloud map, and a schematic diagram of the potential sliding surfaces were output. The cloud maps used different color gradients to indicate the magnitude of stress / strain, and the sliding surface schematic diagram clearly marked the location, inclination angle, and length of each sliding surface. All data was stored in a multi-layered relational database.

[0105] Step S6: Based on a multi-field correlation database, combined with real-time monitoring data of deformation, water content, stress, and ion concentration of expansive soil at different depths and directions, the modification effect of the shallow expansive soil in the area to be treated is verified through inversion calculation, and the determination is made. Check whether the migration depth, ion exchange degree, and reduction in expansibility meet the preset technical requirements; if not, adjust the electric field strength of the electroosmosis device, the alkaline slurry supply rate, or the slurry concentration, and repeat S2 to S5 until the shallow expansive soil modification effect meets the standard.

[0106] If the modification effect of shallow expansive soil meets the preset technical requirements, the overall stability of the expansive soil foundation slope after electroosmosis-alkali slag co-treatment is determined based on the inversion calculation results of the multi-field correlation database. The slope safety factor is calculated and it is determined whether the preset stability standard is met. If the stability standard is not met, the treatment parameters are finely adjusted and S2 to S5 are repeated until the slope meets the preset stability standard.

[0107] Specifically, the first round of stability assessment is as follows:

[0108] Preset stability standard: slope safety factor Furthermore, the maximum displacement change of the soil within 24 hours is ≤0.1mm.

[0109] The analysis results of step S5 were retrieved: After the first round of treatment, the minimum safety factor of the five potential sliding surfaces of the slope was 1.15, which was lower than the preset standard; 24-hour displacement monitoring showed that the displacement of the surface soil in the middle and lower part of the slope was 0.15 mm, which exceeded the threshold.

[0110] Conclusion: The stable standard has not been reached; parameters need to be adjusted and the treatment process repeated. Analysis of the first round of data for the treatment parameter adjustment plan shows that the reason for the substandard safety factor is... Insufficient migration into deeper soil layers results in a low cation exchange rate in deeper soil layers. Based on this, the following adjustment plan is formulated:

[0111] The parameters of the electroosmosis device were adjusted by increasing the DC electric field strength from 2.5 V / cm in the first round to 2.4 V / cm, thereby enhancing the driving force of the electric field to promote... Deep migration is achieved while controlling the current to not exceed 15 A to avoid electrode overheating.

[0112] The parameters of the alkali residue supply device were adjusted as follows: First, the slurry supply rate was increased by 20% from the initial 1.2 L / min to 1.44 L / min, ensuring that the slurry cover layer thickness on the soil surface remained stable at 1.2 cm; second, the alkali residue slurry... The concentration was increased by 0.2 mol / L from 0.6 mol / L to 0.8 mol / L to improve the cation exchange efficiency.

[0113] Repeat step S2 according to the adjusted parameters: adjust the duration of the collaborative treatment to 85% of the duration of the first round, i.e., 40.8 h. During the operation, monitor the electric field strength and supply rate in real time to ensure that the parameters are stable and without abnormalities.

[0114] Repeat steps S3-S4: Perform optical displacement measurement and sample testing again. The results show that the deep soil layer (2.5 m−3 m) The concentration was increased to 0.65 mol / L, a 30% increase compared to the first round; the moisture content decreased to 17%–20%, and the dry density increased to [missing value]. .

[0115] Repeat step S5: Based on the new multi-field parameters, establish a coupled model and calculate that the minimum safety factor of the five potential sliding surfaces is 1.31; the displacement change over 24 hours is reduced to 0.08 mm.

[0116] The final stability assessment determines the safety factor after secondary treatment. and displacement change Once the preset stability standard is met, the treatment operation will be stopped.

[0117] In step S2, the following model formula is used to control the injection flow rate of the alkaline residue slurry: ;in, Indicates the injection flow rate of alkaline residue slurry. This represents the permeability coefficient of expansive soil. This represents the total cross-sectional area of ​​the injection hole. This represents the difference between the injection pressure and the internal pressure of the area to be treated. Indicates the dynamic viscosity of the alkaline residue slurry. This represents the average distance from the injection hole to the boundary of the area to be treated. Indicates the flow attenuation coefficient. Indicates the injection time.

[0118] Specifically, the area of ​​a certain expansive soil foundation slope awaiting treatment. The slope height is 10m, and the slope ratio is 1:2. When installing the alkali residue supply device, a 25mm diameter polyethylene pipe is selected, with a single pipe outlet cross-sectional area of... Operational objective: To control the grout supply rate using a formula, forming a 1cm thick uniform cover layer on the soil surface, driving... Directional migration, while avoiding soil surface heave due to excessive speed.

[0119] Substituting into the formula, we get: Unit conversion: ;

[0120] ;

[0121] Converted to: ;

[0122] Calculate the final supply rate: Based on the actual engineering requirements, it is necessary to ensure a uniform surface coating and adjust accordingly. Up to 1.2, the final Q = 1.2 × 0.000463 ≈ 0.000556 L / min.

[0123] Step S2 includes the following steps:

[0124] Step S21: Check the connection status of the anode and cathode electrodes of the electroosmosis device to ensure that the circuit between the electrodes and the DC power supply is conductive. Use a multimeter to measure the initial resistance value between the electrodes and record the measurement data.

[0125] Step S22: Check the sealing of the storage tank and conveying pipeline of the alkali residue supply device. Pour the alkali residue slurry into the storage tank, start the conveying pump, and let the slurry circulate in the pipeline for a preset time. Observe whether there is any slurry leakage at the pipeline connection. At the same time, confirm that the slurry concentration is uniform and there is no obvious sedimentation.

[0126] Step S23: Based on the characteristics of the expansive soil in the area to be treated, set the initial intensity of the DC electric field and the initial supply rate of the alkali slag slurry; input the set parameters into the control terminal, and send the start command to the electroosmosis device and the alkali slag supply device to ensure that the slurry forms a uniform covering layer on the surface of the area to be treated.

[0127] Step S24: During the electroosmosis and alkali slag supply process, at preset time intervals, the electric field strength and slurry supply rate data are collected through the control terminal; at the same time, observe whether there are any abnormal phenomena such as bulging or cracks on the surface of the area to be treated, and record the abnormal data.

[0128] Specifically, step S21, checking the connection status of the electroosmosis device: Select metal anode / cathode electrodes with a diameter of 25mm and a length of 6m, and arrange them alternately at 1m intervals along the boundary of the slope to be treated area. The electrodes should be inserted into the soil to a depth of 4m, with 0.4m protruding above the ground for wiring. Connect the electrodes to the DC regulated power supply via copper core cables. Use a digital multimeter with a range of 0-100Ω to measure the initial resistance value between adjacent anode and cathode electrodes. The measurement results show that the resistance value between the electrodes is within the range of 8-15Ω, which is within the normal range of 5-20Ω. This indicates that the circuit is conductive and there are no poor contacts or short circuits. Record the resistance data for each group of electrodes and archive them.

[0129] Step S22: Check the sealing performance and slurry condition of the alkali slag supply device: The alkali slag supply device is equipped with a 150L corrosion-resistant storage tank, an adjustable flow pump, and a 25mm diameter polyethylene delivery pipe. The pipe outlet is buried 0.3m below the slope surface, with a total of 25 outlet points. Prepare a solution containing... A 0.6 mol / L alkaline residue slurry was poured into a storage tank, and the transfer pump was started to circulate the slurry in the pipeline for 45 minutes. All pipe joints, valves, and seals of the storage tank were inspected, and no slurry leakage was observed. The slurry in the tank was observed to have no obvious particle sedimentation, and the concentration was uniform after stirring. The sealing performance of the device and the state of the slurry were determined to be up to standard.

[0130] Step S23: Set initial operating parameters and start the device: Based on the soil moisture content of 30%, set the initial DC electric field strength to 2.5V / cm, corresponding to a power supply output current controlled within the 8-12A range. Considering the area to be treated is 200... The goal was to form a 1cm thick uniform cover layer on the soil surface, and the initial supply rate of the alkaline slurry was calculated to be 1.0L / min. The electric field strength and slurry supply rate parameters were input into the PLC control terminal, and the start command was clicked. The electroosmosis device and the supply device operated synchronously. On-site observation showed that the slurry output from all 25 pipe outlets was uniform, and a continuous slurry cover layer formed on the soil surface after 30 minutes.

[0131] Step S24: Real-time monitoring of the operation process and parameters: Set the monitoring interval to 30 minutes, and automatically collect data on electric field strength and slurry supply rate through the control terminal, recording the average data once per hour. During the operation, arrange for dedicated personnel to inspect the slope surface, focusing on whether there are any abnormalities such as bulging or cracks; when the collaborative operation reaches the 24th hour, a fine crack with a length of 3cm and a width of 1mm is found in a local area of ​​the slope. Immediately record the location and size of the crack, as well as the electric field strength (1.95V / cm) and supply rate (0.95L / min) data at the corresponding time. Adjust the electric field strength to 2.5V / cm and increase the supply rate to 1.1L / min. In subsequent inspections, the crack did not continue to expand. After the operation continues for 48 hours, the operation is suspended in the order of stopping the supply pump first and then cutting off the power supply.

[0132] Step S3 includes the following sub-steps:

[0133] Step S31: Divide the surface of the area to be treated into multiple measurement sub-regions. Set no less than three optical measurement markers in each sub-region to ensure that the markers are within the field of view of the optical measurement device. Adjust the focal length and angle of the measurement device to make the markers clear.

[0134] Step S32: Start the optical measurement device to continuously photograph the marker points in each sub-region, acquire image data at different time points, use image analysis software to extract the coordinate information of the marker points, and calculate the coordinate changes of the marker points at adjacent time points.

[0135] Step S33: Use drilling equipment to drill test holes at different locations in the area to be treated, insert optical measuring probes into the test holes at different depths, measure the changes in the transverse and longitudinal dimensions of the expansive soil at each depth, and record the measurement data at each depth.

[0136] Step S34: Collect expansive soil samples at different locations in the area to be treated using the ring cutter method. Collect at least three parallel samples at each collection location. Place the samples in a sealed container, label the collection location and depth information, and send them to the laboratory for subsequent testing.

[0137] Specifically, step S31, dividing the measurement sub-region and arranging optical markers: according to the specification of 5m×5m, 200 The area to be treated is divided into 8 measurement sub-regions, each with an area of ​​25. Five optical measurement markers were placed at the four corners and center of each sub-region. 15mm diameter reflective metal dots were used as markers and affixed to a flat, debris-free area on the slope surface, ensuring no obstruction of the markers within each sub-region. A laser displacement sensor with an accuracy of 0.01mm was used as the optical measurement device. The sensor was mounted on stable platforms on both sides of the slope, and its focal length was adjusted to 0.8m, with the emission angle perpendicular to the plane of the marker. After calibration, all markers were clearly imaged without any ghosting.

[0138] Step S32: Acquire image data of marker points and calculate coordinate changes: Activate the laser displacement sensor, set a shooting interval of 15 minutes, and continuously capture images of 40 marker points in 8 sub-regions, obtaining 25 sets of image data within 6 hours after the work was paused. Import the image data into image analysis software, extract the coordinate information of each marker point on the x-axis (lateral) and y-axis (vertical), and calculate the coordinate difference between adjacent time points. Data analysis shows that the maximum lateral displacement of the surface soil marker points is 0.32 mm, and the maximum longitudinal compression is 0.18 mm. The displacement changes are stable without abrupt changes, consistent with the deformation law of the soil after treatment.

[0139] Step S33: Drilling to measure soil deformation data at different depths: Using a geological drilling machine with a 70mm diameter, test holes were drilled at the center of the four diagonal sub-areas of the area to be treated, to a depth of 3m underground to ensure penetration of the treatment layer. A 20mm diameter miniature optical measuring probe was inserted into the test hole, and soil deformation data were measured at 0.5m intervals: 0.5m, 1.0m, 1.5m, 2.0m, 2.5m, and 3.0m underground. The recorded data showed that at a depth of 0.5m-1.5m, the lateral displacement of the soil was 0.21mm-0.32mm, and the longitudinal compression was 0.12mm-0.18mm; at a depth of 2.0m-3.0m, the displacement decreased significantly, with lateral displacement ≤0.10mm and longitudinal compression ≤0.05mm, indicating that the deeper soil layers were more stable.

[0140] Step S34: Standardize the collection of expansive soil samples and label relevant information: Using a ring cutter with an inner diameter of 100mm and a height of 200mm, select 6 sampling locations around the 4 test wells and 2 central sub-regions. Each sampling location corresponds to 3 depths: 0.5m, 1.5m, and 2.5m underground. Collect 3 parallel samples at each depth to avoid disturbing the soil structure during sampling, obtaining a total of 6×3×3=54 expansive soil samples. Place the samples in sealed plastic bags and label them with the following information: Project Name - Sampling Location Number - Depth. Transport them to the laboratory for constant temperature and humidity storage within 2 hours, awaiting subsequent physical and mechanical property testing.

[0141] In step S3, the following model formula is used to calculate the lateral displacement of the expansive soil: ,in, This indicates the lateral displacement of expansive soil. Indicates the magnification factor of the optical measuring device. This represents the change in length of a reference line segment in optical measurements. This indicates the vertical distance from the measurement point to the baseline. This represents the strain of expansive soil in the x-direction. This represents the strain of expansive soil in the y-direction.

[0142] Step S4 includes the following sub-steps:

[0143] Step S41: Place the collected expansive soil sample in a constant temperature and humidity environment. After the sample condition stabilizes, use a balance to measure the wet mass of the sample. Then put the sample into an oven and dry it at a preset temperature until constant weight. Measure the dry mass of the sample and calculate the sample moisture content.

[0144] Step S42: Take the dried sample, measure the relative density of the solid particles using the specific gravity bottle method, measure the total volume of the sample using a volume analyzer, and calculate the dry density of the sample by combining the dry mass data.

[0145] Step S43: Prepare standard specimens from some expansive soil samples, place them in a triaxial shear apparatus, apply different confining pressures to conduct shear tests, record the stress and strain data during the test, and obtain the cohesion and internal friction angle of the specimens through data fitting.

[0146] Step S44: Use a dilatometer to test the expansion force and expansion rate of the sample, obtain expansion characteristic parameters, and use an ion electrode to detect the cation type and concentration of different samples to test the expansion deformation data under different cation conditions.

[0147] Step S45: Associate all the moisture content, dry density, cohesion, internal friction angle, expansion characteristics, and cation parameters obtained from the tests with the corresponding collection location, depth information, and displacement data, and enter them into the computer database to establish a multi-field association database indexed by "location-depth-multi-field parameters".

[0148] In step S44, the following model formula is used to obtain the dry density of expansive soil: ,in, This indicates the dry density of expansive soil. This indicates the mass of solid particles in the expansive soil sample. This represents the total volume of the expansive soil sample. This indicates the moisture content of the expansive soil sample.

[0149] Specifically, this embodiment is based on 54 expansive soil samples from an expansive soil foundation slope project of a highway. The samples cover 6 sampling locations and 3 depth gradients (0.5m, 1.5m, 2.5m). Three parallel samples are set at each depth. The test objective is to obtain soil seepage field, mechanical field, and chemical field parameters and construct a multi-field correlation database.

[0150] Step S41, Moisture Content Test: Remove 54 expansive soil samples from the sealed bag and place them in a constant temperature and humidity chamber at 23℃ and 50% relative humidity for 24 hours to allow the samples to reach equilibrium with the environment. Using an electronic balance with an accuracy of 0.001g, measure the wet mass of each sample sequentially and record the data (e.g., the wet masses of a parallel sample at a depth of 0.5m are 128.542g, 129.105g, and 128.871g, respectively). Place the samples in an oven at 105℃ and dry them for 24 hours until constant weight. After cooling to room temperature, measure the dry mass (corresponding to dry masses of 106.215g, 106.732g, and 106.508g).

[0151] According to the formula The moisture content was calculated based on wet and dry conditions. The moisture content of this group of samples was 21.02%, 21.00%, and 21.00%, with a mean of 21.01%, which is within the treatment target range of 15%-25%.

[0152] Step S42, Dry Density Test: Take the dried sample and measure the relative density of the solid particles using the specific gravity bottle method. The average relative density of the particles in this group of samples is measured to be [value missing]. The total volume of the sample inside the ring cutter was measured using a volumetric analyzer. The ring cutter had an inner diameter of 100 mm and a height of 200 mm, and the volume was 1570.8 g. The calculated mean volume of a single sample is 125.6. .

[0153] According to the formula Calculate the dry density, and substituting the data, the mean dry density of this sample group is 1.76 g / cm³, which satisfies 1.6. -1.9 The treatment requirements.

[0154] Step S43, Cohesion and Internal Friction Angle Test: A representative soil sample was selected from the 0.5m depth sample and prepared into a standard triaxial shear specimen with a diameter of 39.1mm and a height of 80mm. The specimen was placed in the pressure chamber of a triaxial shear apparatus, and three confining pressures of 50kPa, 100kPa, and 150kPa were applied respectively. The strain rate was set to 0.025mm / min for shear tests. The axial stress-strain curves under different confining pressures were recorded. By fitting the curves using the Mohr-Coulomb strength theory, the average cohesion of the soil at this depth was found to be 26kPa, and the average internal friction angle was 21°, both within the acceptable ranges of 15kPa-35kPa and 15°-25°, respectively.

[0155] Step S44, Expansion Characteristics and Cation Test: Samples of the same depth were prepared into ring-shaped specimens with a diameter of 50 mm and a height of 20 mm. These specimens were placed in a dilatometer and saturated with water under no-load conditions. The average expansion force was measured to be 18 kPa, and the average expansion rate was 1.2%, significantly lower than before treatment (expansion force 45 kPa, expansion rate 3.5%). The ion-selective electrode method was used to detect the type and concentration of cations in the samples. The results showed: The concentration increased from 0.05 mol / L before treatment to 0.48 mol / L. The concentration decreased from 0.52 mol / L to 0.09 mol / L, proving... It effectively replaced low-valent cations in the soil.

[0156] Step S45: Database Construction: Establish a database with "sampling location-depth-parameter type" as the core index. The fields include: project number, sampling location coordinates, depth, moisture content, dry density, cohesion, internal friction angle, expansion force, expansion rate, cation concentration, etc.

[0157] Step S5 includes the following sub-steps:

[0158] Step S51: Extract displacement data, mechanical parameters and chemical field parameters of expansive soil at different depths and locations in the area to be treated from the associated database, divide the data into multiple calculation units according to spatial coordinates, and determine the boundary range and average value of each parameter of each calculation unit.

[0159] Step S52: Input the parameters of each calculation unit into the preset algorithm to construct the geometric model of the slope and the mechanical model coupled with the seepage field-mechanical field-chemical field. Set the boundary conditions and load conditions of the model. The boundary conditions include the constraints of the top, bottom and sides of the slope, and the load conditions include the self-weight of the expansive soil and the external additional load.

[0160] Specifically, from a multi-field correlation database, all parameters were extracted from six sampling locations and three depth gradients (0.5m, 1.5m, and 2.5m) within the area to be treated. These parameters included lateral displacement (0.10mm-0.32mm), longitudinal compression (0.05mm-0.18mm), moisture content (18%-22%), dry density (1.70g / cm³-1.85g / cm³), cohesion (20kPa-30kPa), and internal friction angle (18°-22°). Concentration (0.40 mol / L - 0.48 mol / L); the 200㎡ treatment area was divided into 50 calculation units using a 2m × 2m spatial coordinate grid, with each unit corresponding to one grid node. Parameter mean determination: the sampled data within the coverage area of ​​each calculation unit were arithmetically averaged to determine the unit parameter values. For example, the parameter mean values ​​for calculation unit C08 (corresponding to a depth of 0.5m) are: moisture content 20.5%, dry density 1.78 g / cm³, cohesion 27 kPa, internal friction angle 20°. Concentration 0.46 mol / L.

[0161] Step S53: Run the algorithm to calculate the model, obtain the stress distribution and strain distribution data of each calculation unit in the slope, combine the influence of cation concentration change on expansibility, determine the location and shape of the potential sliding surface, and calculate the anti-sliding force and sliding force on the sliding surface.

[0162] Specifically, based on the actual dimensions of the slope, a two-dimensional geometric model was established in the finite element analysis software. The model height was 10m, the horizontal length at the slope toe was 20m, and the slope ratio was 1:2. The computational cells corresponded one-to-one with the 50 grids previously divided. The seepage field-mechanical field-chemical field coupling algorithm was selected, and the cation concentration was used as the core parameter of the chemical field. The correlation function between concentration and soil cohesion and internal friction angle; the higher the concentration, the higher the mechanical parameter correction factor. The larger.

[0163] Step S54: Based on the calculation results of anti-sliding force and sliding force, determine the safety factor of the slope, and at the same time generate stress and strain distribution cloud maps and sliding surface schematic diagrams, and store the calculation results and graphic data in the database.

[0164] In step S54, the safety factor of the slope is calculated using the following model formula: ;in, Indicates the slope safety factor. Indicates the first The cohesion of expansive soil in each calculation unit. Indicates the first The normal stress on the expansive soil in each calculation unit Indicates the first The internal friction angle of expansive soil in each calculation unit. Indicates the first The length of the sliding surface of each computational unit. This indicates the unit weight of expansive soil. Indicates the first The slope height corresponding to each calculation unit Indicates the dip angle of the slope sliding surface. This indicates the total number of computing units.

[0165] The specific implementation process of step S6 is as follows:

[0166] Step S61: Real-time monitoring data and multi-field database data linkage retrieval: Extract full-dimensional real-time monitoring data of the area to be treated from the engineering monitoring terminal, and stratify it by depth ( , , , A data index was established for the shallow core area and spatial locations, and the basic calibration data of the expansive soil was retrieved from a multi-field correlation database. The real-time monitoring data and the basic calibration data in the database were matched one by one according to depth, location, and index to form a dedicated dataset for verifying the modification effect. Abnormal data (such as extreme values ​​caused by monitoring equipment failure or local soil disturbance) were removed to ensure data validity. The extracted indicators include: transverse / longitudinal deformation of soil at different depths / directions, water content distribution, soil stress (normal / shear stress) data, and pore solution data. The cation concentration values ​​are equal, and the data sampling frequency is consistent with the test frequency of the preceding S3 / S4 (e.g., every 0.5h / 1h).

[0167] Specifically, basic calibration data for the expansive soil was retrieved from a multi-field correlation database, including: initial expansive force / expansion rate, original cation concentration, and different... The correlation fitting curves between concentration-corresponding swelling attenuation coefficients, electroosmotic parameters (electric field strength / slurry rate) and ion migration depth, and the quantitative correspondence between ion exchange degree and soil swelling.

[0168] Step S62: Quantitative analysis of core indicators of modification effect based on inversion calculation: The modification effect is fitted through inversion calculation. The concentration variation curve with soil depth is used as the design critical concentration for modification to determine the soil depth corresponding to the threshold in the curve. Based on the cationic composition of each depth layer obtained by inversion calculation, and combined with the correlation model of cationic composition and expansibility parameters in the database, the expansibility force and free expansibility of each depth layer after treatment are calculated. Then, compared with the initial value before treatment, the reduction rate of expansibility force and the reduction rate of expansibility are obtained.

[0169] Specifically as follows:

[0170] Transfer depth quantization determination: fitted by inversion calculation The concentration versus soil depth curve is used to design the critical concentration for modification (e.g., after treatment). Using a concentration increase of ≥50% from the initial value as a threshold, the soil depth corresponding to this threshold in the curve is determined, which is the actual depth. Effective migration depth; simultaneously calculates the depth of each layer. The uniformity of concentration helps determine whether there are areas of insufficient local migration.

[0171] Quantitative calculation of ion exchange level: based on (after treatment at a certain depth layer) Adsorption capacity - initial The ion exchange rate of each depth layer is calculated based on the ratio of the initial adsorption amount of low-valent cations to the total initial adsorption amount of low-valent cations.

[0172] Quantitative solution for the reduction in expansibility: based on the cation composition of each depth layer obtained from inversion calculation ( (Proportion), combined with the correlation model in the database, calculate the expansion force and free expansion rate of each depth layer after treatment, and then compare it with the initial value before treatment to obtain the reduction rate of expansion force and the reduction rate of expansion rate, which is the actual reduction of expansion.

[0173] Step S63: Benchmarking the Modification Effect against the Preset Technical Requirements: The actual values ​​of the indicators obtained from the inversion calculation are compared with the preset technical requirements for the modification of shallow expansive soil in the project. Only when all depth layers meet the preset requirements can the modification effect be judged to be up to standard. If any layer or a core indicator is not met, the modification effect is judged to be down to standard, and the parameter adjustment stage is entered.

[0174] Step S64, Targeted adjustment of treatment parameters in case of non-compliance: Based on the type and degree of deviation of the non-compliance indicators, the three core parameters of the electroosmosis device, the electric field strength, the alkaline slurry supply rate, and the alkaline slurry concentration are adjusted in a targeted manner, and the adjustment range is set according to the degree of deviation.

[0175] Step S65, Secondary Verification of Treatment and Modification Effects: Restart the electroosmosis unit and alkali residue supply unit according to the adjusted parameters, and repeat steps S2, S3, S4, and S5. Adjust the operation time appropriately according to the degree of deviation. After completing the repeated operation, follow this process again. The steps involve a second verification of the modification effect of shallow expansive soil. If the second verification meets the standards, the modification effect verification stage ends and the overall slope stability assessment stage begins. If the standards are still not met, the parameters are optimized again according to the principle of step S64 until the modification effect fully meets the preset technical requirements.

[0176] It is worth noting that the various units included in the above system embodiments are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0177] Furthermore, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware, and the corresponding program can be stored in a computer-readable storage medium.

[0178] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An in-situ treatment technology for expansive soil foundation slopes and a stability assessment method thereof, characterized in that, Includes the following steps: Step S1: Select the area to be treated on the expansive soil foundation slope, and install an electroosmosis device and an alkali residue supply device; wherein, the electroosmosis device includes multiple anode electrodes and cathode electrodes, which are alternately arranged at a preset interval at the boundary of the area to be treated; the alkali residue supply device includes a storage tank and a conveying pipeline, with the pipeline outlet located at the surface or shallow layer of the area to be treated, for providing a solution containing... Alkali residue slurry; Step S2: Start the electroosmosis device and apply a DC electric field to the area to be treated, using the electric field force to drive the alkaline residue slurry... The process involves migrating the slurry towards the expansive soil to replace the low-valence cations adsorbed in the soil; simultaneously, the supply rate of the alkaline slurry is controlled to form a slurry covering layer on the surface of the area to be treated, and the operation is suspended after a preset duration. Step S3: Use an optical measuring device to perform linear dimension measurement of the area to be treated, obtain the lateral displacement and longitudinal compression of the expansive soil at different depths, and collect expansive soil samples at different locations within the area to be treated. Step S4: Perform physical and mechanical property tests on the collected expansive soil samples to obtain parameters such as moisture content, dry density, cohesion, and internal friction angle; test the expansive soil's swelling characteristics, including swelling force and swelling rate; test the expansive soil's swelling deformation and swelling force parameters under different cation types and concentrations; and construct a multi-field correlation database of expansive soil deformation and seepage field, mechanical field, and chemical field by combining displacement data obtained from optical measurements. Step S5: Based on a multi-field correlation database, a preset algorithm is used to analyze the stability of the expansive soil foundation slope after electro-osmosis-alkali slag co-treatment and calculate the safety factor of the slope. The algorithm establishes a slope stability assessment model coupled with seepage field, mechanical field and chemical field by calling displacement, mechanical field and chemical field parameters at different depths and locations in the database and performs inversion calculation. Step S6: Based on a multi-field correlation database, combined with real-time monitoring data of deformation, water content, stress, and ion concentration of expansive soil at different depths and directions, the modification effect of the shallow expansive soil in the area to be treated is verified through inversion calculation, and the determination is made. Check whether the migration depth, ion exchange degree, and reduction in expansibility meet the preset technical requirements; if not, adjust the electric field strength of the electroosmosis device, the alkaline slurry supply rate, or the slurry concentration, and repeat S2 to S5 until the shallow expansive soil modification effect meets the standard.

2. The in-situ treatment technology and stability assessment method for expansive soil foundation slopes according to claim 1, characterized in that, Step S2 includes the following steps: Step S21: Check the connection status of the anode and cathode electrodes of the electroosmosis device to ensure that the circuit between the electrodes and the DC power supply is conductive. Use a multimeter to measure the initial resistance value between the electrodes and record the measurement data. Step S22: Check the sealing of the storage tank and conveying pipeline of the alkali residue supply device. Pour the alkali residue slurry into the storage tank, start the conveying pump, and let the slurry circulate in the pipeline for a preset time. Observe whether there is any slurry leakage at the pipeline connection. At the same time, confirm that the slurry concentration is uniform and there is no obvious sedimentation. Step S23: Based on the characteristics of the expansive soil in the area to be treated, set the initial intensity of the DC electric field and the initial supply rate of the alkali slag slurry; input the set parameters into the control terminal, and send the start command to the electroosmosis device and the alkali slag supply device to ensure that the slurry forms a uniform covering layer on the surface of the area to be treated. Step S24: During the electroosmosis and alkali slag supply process, at preset time intervals, the electric field strength and slurry supply rate data are collected through the control terminal; at the same time, observe whether there are any abnormal phenomena such as bulging or cracks on the surface of the area to be treated, and record the abnormal data.

3. The in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to claim 1, characterized in that, Step S3 includes the following sub-steps: Step S31: Divide the surface of the area to be treated into multiple measurement sub-regions. Set no less than three optical measurement markers in each sub-region to ensure that the markers are within the field of view of the optical measurement device. Adjust the focal length and angle of the measurement device to make the markers clear. Step S32: Start the optical measurement device to continuously photograph the marker points in each sub-region, acquire image data at different time points, use image analysis software to extract the coordinate information of the marker points, and calculate the coordinate changes of the marker points at adjacent time points. Step S33: Use drilling equipment to drill test holes at different locations in the area to be treated, insert optical measuring probes into the test holes at different depths, measure the changes in the transverse and longitudinal dimensions of the expansive soil at each depth, and record the measurement data at each depth. Step S34: Collect expansive soil samples at different locations in the area to be treated using the ring cutter method. Collect at least three parallel samples at each collection location. Place the samples in a sealed container, label the collection location and depth information, and send them to the laboratory for subsequent testing.

4. The in-situ treatment technology and stability assessment method for expansive soil foundation slopes according to claim 1, characterized in that, In step S3, the following model formula is used to calculate the lateral displacement of the expansive soil: ,in, This indicates the lateral displacement of expansive soil. Indicates the magnification factor of the optical measuring device. This represents the change in length of a reference line segment in optical measurements. This indicates the vertical distance from the measurement point to the baseline. This represents the strain of expansive soil in the x-direction. This represents the strain of expansive soil in the y-direction.

5. The in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to claim 1, characterized in that, Step S4 includes the following sub-steps: Step S41: Place the collected expansive soil sample in a constant temperature and humidity environment. After the sample condition stabilizes, use a balance to measure the wet mass of the sample. Then put the sample into an oven and dry it at a preset temperature until constant weight. Measure the dry mass of the sample and calculate the sample moisture content. Step S42: Take the dried sample, measure the relative density of the solid particles using the specific gravity bottle method, measure the total volume of the sample using a volume analyzer, and calculate the dry density of the sample by combining the dry mass data. Step S43: Prepare standard specimens from some expansive soil samples, place them in a triaxial shear apparatus, apply different confining pressures to conduct shear tests, record the stress and strain data during the test, and obtain the cohesion and internal friction angle of the specimens through data fitting. Step S44: Use a dilatometer to test the expansion force and expansion rate of the sample, obtain expansion characteristic parameters, and use an ion electrode to detect the cation type and concentration of different samples to test the expansion deformation data under different cation conditions. Step S45: Associate all the moisture content, dry density, cohesion, internal friction angle, expansion characteristics, and cation parameters obtained from the tests with the corresponding collection location, depth information, and displacement data, and enter them into the computer database to establish a multi-field association database indexed by "location-depth-multi-field parameters".

6. The in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to claim 5, characterized in that, In step S44, the following model formula is used to obtain the dry density of expansive soil: ,in, This indicates the dry density of expansive soil. This indicates the mass of solid particles in the expansive soil sample. This represents the total volume of the expansive soil sample. This indicates the moisture content of the expansive soil sample.

7. The in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to claim 1, characterized in that, Step S5 It includes the following steps: Step S51: Extract displacement data, mechanical parameters and chemical field parameters of expansive soil at different depths and locations in the area to be treated from the associated database, divide the data into multiple calculation units according to spatial coordinates, and determine the boundary range and average value of each parameter of each calculation unit. Step S52: Input the parameters of each calculation unit into the preset algorithm to construct the geometric model of the slope and the mechanical model coupled with the seepage field-mechanical field-chemical field. Set the boundary conditions and load conditions of the model. The boundary conditions include the constraints of the top, bottom and sides of the slope, and the load conditions include the self-weight of the expansive soil and the external additional load. Step S53: Run the algorithm to calculate the model, obtain the stress distribution and strain distribution data of each calculation unit in the slope, combine the influence of cation concentration change on expansibility, determine the location and shape of the potential sliding surface, and calculate the anti-sliding force and sliding force on the sliding surface. Step S54: Based on the calculation results of anti-sliding force and sliding force, determine the safety factor of the slope, and at the same time generate stress and strain distribution cloud maps and sliding surface schematic diagrams, and store the calculation results and graphic data in the database.

8. The in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to claim 1, characterized in that, In step S53, based on the actual dimensions of the slope, a two-dimensional geometric model is established in the finite element analysis software. The model height is 10m, the horizontal length at the slope toe is 20m, and the slope ratio is 1:

2. The calculation units correspond one-to-one with the 50 grids previously divided. The seepage field-mechanical field-chemical field coupling algorithm is selected, and the cation concentration is used as the core parameter of the chemical field. The correlation function between concentration and soil cohesion and internal friction angle.

9. The in-situ treatment technology for expansive soil foundation slopes and its stability assessment method according to claim 1, characterized in that, In step S54, the safety factor of the slope is calculated using the following model formula: ;in, Indicates the slope safety factor. Indicates the first The cohesion of expansive soil in each calculation unit. Indicates the first The normal stress on the expansive soil in each calculation unit Indicates the first The internal friction angle of expansive soil in each calculation unit. Indicates the first The length of the sliding surface of each computational unit. This indicates the unit weight of expansive soil. Indicates the first The slope height corresponding to each calculation unit Indicates the dip angle of the slope sliding surface. This indicates the total number of computing units.

10. An in-situ treatment technique for expansive soil foundation slopes and a stability assessment method thereof according to claim 1, characterized in that, The specific implementation process of step S6 is as follows: Step S61: Real-time monitoring data and multi-site database data linkage retrieval: Extract real-time monitoring data of the area to be treated from the engineering monitoring terminal, establish data index according to depth layering and spatial location, and retrieve the basic calibration data of the expansive soil from the multi-site related database. Match the real-time monitoring data with the basic calibration data of the database according to depth, location and index. Step S62: Quantitative analysis of core indicators of modification effect based on inversion calculation: The modification effect is fitted through inversion calculation. The concentration variation curve with soil depth is used as the design critical concentration for modification to determine the soil depth corresponding to the threshold in the curve. Based on the cationic composition of each depth layer obtained by inversion calculation, and combined with the correlation model of cationic composition and expansibility parameters in the database, the expansibility force and free expansibility of each depth layer after treatment are calculated. Then, compared with the initial value before treatment, the reduction rate of expansibility force and the reduction rate of expansibility are obtained. Step S63: Benchmarking the Modification Effect against the Preset Technical Requirements: The actual values ​​of the indicators obtained from the inversion calculation are compared with the preset technical requirements for the modification of shallow expansive soil in the project. Only when all depth layers meet the preset requirements can the modification effect be judged to be up to standard. If any layer or a core indicator is not met, the modification effect is judged to be down to standard, and the parameter adjustment stage is entered. Step S64, Targeted adjustment of treatment parameters in case of non-compliance: Based on the type and degree of deviation of the non-compliance indicators, the three core parameters of the electroosmosis device, the electric field strength, the alkaline slurry supply rate, and the alkaline slurry concentration are adjusted in a targeted manner, and the adjustment range is set according to the degree of deviation. Step S65, Secondary Verification of Treatment and Modification Effects: Restart the electroosmosis unit and alkali residue supply unit according to the adjusted parameters, and repeat steps S2, S3, S4, and S5. Adjust the operation time appropriately according to the degree of deviation. After completing the repeated operation, follow this process again. The steps involve a second verification of the modification effect of shallow expansive soil. If the second verification meets the standards, the modification effect verification stage ends and the overall slope stability assessment stage begins. If the standards are still not met, the parameters are optimized again according to the principle of step S64 until the modification effect fully meets the preset technical requirements.

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