Arsenic-contaminated soil stratification and consolidation excavation planning system and method

Abstract

This invention discloses a stratified and merged excavation planning system and method for arsenic-contaminated soil, comprising: an acquisition module; a modeling module connected to the acquisition module; a first calculation module, wherein the constraints include a contamination concentration gradient threshold, a soil layer thickness threshold, and a remediation target concentration threshold, the first calculation module being connected to the modeling module; an update module connected to the modeling module and the first calculation module; a second calculation module connected to the modeling module; and an output module connected to the modeling module. This invention solves the problems of existing stratified excavation operations for arsenic-contaminated soil, which suffer from arbitrary merging of excavations, easily leading to excessive and uncontrolled remediation target soil excavation, and deviation from the remediation boundaries set in the risk assessment.

Description

Technical Field

[0001] This invention relates to the field of pollution remediation technology, specifically to a system and method for planning the stratified and combined excavation of arsenic-contaminated soil. Background Technology

[0002] With the acceleration of industrialization and the prominence of historical pollution problems, arsenic-contaminated soil remediation has become a crucial issue in environmental engineering. Remediation methods have evolved from simple end-of-pipe remediation technologies such as chemical stabilization and phytoremediation to a more engineering-oriented, systematic, and construction-driven comprehensive remediation model. In the remediation of large contaminated sites, excavation, as a prerequisite for the transfer and subsequent treatment of contaminated soil, directly determines the overall remediation cycle and engineering risks in terms of efficiency and safety. However, current mainstream remediation technologies still focus on the development of remediation materials and the optimization of pollutant passivation mechanisms, lacking systematic modeling and quantitative constraints on the engineering organization logic, soil layer merging strategies, and dynamic construction control during the excavation stage. This leads to frequent problems such as long-term exposure of the excavation pit, redundant monitoring frequency, and misallocation of construction resources, severely restricting the economic efficiency and safety of remediation projects.

[0003] For arsenic-contaminated soil, existing projects generally follow the traditional model of "layer-by-layer stripping, independent monitoring, and segmented transportation." While this ensures the accuracy of pollution boundary identification, the repetitive mechanical work and fixed monitoring points result in lengthy construction periods and increased costs. Especially in areas with dense structures such as elevator shafts and fire shafts, or in thin-layer contamination zones, the layered machinery struggles to operate precisely, leading to a sharp drop in construction efficiency, and the frequent excavation-backfilling cycles exacerbate the risk of slope instability.

[0004] Existing technologies suffer from three structural defects at the level of layered excavation optimization: First, the lack of a tolerance threshold for increased contaminated soil and the arbitrary nature of combined excavation can easily lead to an uncontrolled over-extraction of the target soil for remediation, deviating from the remediation boundary set in the risk assessment. Secondly, the lack of a hierarchical merging priority model and the absence of a differentiated response mechanism for differences in construction difficulty (such as thin layers and irregular areas) have led to an imbalance between mechanical efficiency and engineering risks. Third, the lack of a dynamic calculation framework for excavation volume makes it impossible to predict the quantitative impact of merging operations on the frequency of foundation pit monitoring, the amount of clean soil replacement, and the overall construction period, resulting in construction plan adjustments relying on experience-based judgment rather than data-driven approaches.

[0005] The aforementioned deficiencies are particularly prominent in complex contaminated profiles with a depth of up to 27 meters and as many as 30 layers. There is an urgent need to develop a layered and merged excavation methodology that integrates engineering constraints, risk control, and efficiency optimization to achieve the synergistic goal of precise stripping of contaminated soil, minimization of pit exposure time, and dynamic anchoring of remediation objectives. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, a layered and combined excavation planning system and method for arsenic-contaminated soil are provided to address the problems of arbitrary excavation and excessive and uncontrolled excavation of arsenic-contaminated soil in existing layered excavation operations, which may lead to deviations from the remediation boundary set by the risk assessment.

[0007] To achieve the above objectives, a stratified and combined excavation planning system for arsenic-contaminated soil is provided, comprising: Acquisition module for obtaining three-dimensional spatial pollution concentration distribution data of arsenic-contaminated sites to be remediated; A modeling module for constructing a pollution concentration gradient field model based on the pollution concentration distribution data is connected to the acquisition module; A first calculation module is used to determine adjacent soil layers one by one based on constraints using a greedy algorithm to output layered structure data. The constraints include a pollution concentration gradient threshold, a soil layer thickness threshold, and a remediation target concentration threshold. The first calculation module is connected to the modeling module. An update module for updating the hierarchical structure data of the pollution concentration gradient field model and the pollution concentration distribution data corresponding to each merged soil layer based on the merged soil layer optimization sequence is connected to the modeling module and the first calculation module. A second calculation module, connected to the modeling module, is used to calculate the excavation volume of each merged soil layer based on the updated pollution concentration gradient field model and hierarchical structure data. An output module for outputting the updated layered structure data of the pollution concentration gradient field model and the corresponding excavation volume of the merged soil layers is connected to the modeling module.

[0008] Furthermore, the pollution concentration gradient threshold is the rate of change in arsenic concentration between adjacent soil layers to be merged.

[0009] Furthermore, the target concentration threshold for remediation is the overall average arsenic concentration of the soil layers to be merged.

[0010] Furthermore, the soil layer thickness threshold is the range of soil layer thicknesses to be merged.

[0011] Furthermore, it also includes a correction module. The acquisition module includes a first acquisition unit for acquiring three-dimensional spatial pollution concentration distribution data of the arsenic contaminated site to be remediated and a second acquisition unit for acquiring the actual pollution concentration value at the bottom of each merged soil layer. The second acquisition unit is connected to the correction module, and the correction module is connected to the modeling module and the first calculation module. After a combined soil layer is excavated, the correction module compares the predicted pollution concentration value of the combined soil layer with the actual pollution concentration value, and generates a correction command when the difference between the actual pollution concentration value and the predicted pollution concentration value exceeds a preset threshold. The first calculation module receives the correction instruction and recalculates and outputs the layered structure data of the remaining soil layers.

[0012] This invention provides a method for planning the stratified excavation of arsenic-contaminated soil using a stratified and merged excavation planning system, comprising the following steps: a. The acquisition module acquires the three-dimensional spatial distribution data of the arsenic contaminated site to be remediated; b. The modeling module constructs a pollution concentration gradient field model based on the pollution concentration distribution data; c. The first calculation module, based on constraints, uses a greedy algorithm to determine adjacent soil layers one by one to output layered structure data; d. The update module updates the layered structure data of the pollution concentration gradient field model and the pollution concentration distribution data corresponding to each merged soil layer based on the optimized sequence of the merged soil layers; e. The second calculation module calculates the excavation volume of each merged soil layer based on the updated pollution concentration gradient field model and layered structure data. f. The output module outputs the updated layered structure data of the pollution concentration gradient field model and the corresponding excavation volume of the merged soil layers.

[0013] Furthermore, the arsenic-contaminated soil stratification and merging excavation planning system also includes a correction module, and the arsenic-contaminated soil stratification and merging excavation planning method also includes the following steps: g. Based on the layered structure data and the excavation volume, each merged soil layer is excavated from top to bottom. After the excavation of a merged soil layer, the second acquisition unit acquires the actual pollution concentration value at the bottom of each merged soil layer. h. The correction module compares the predicted pollution concentration value of the merged soil layer with the actual pollution concentration value, and generates a correction instruction when the difference between the actual pollution concentration value and the predicted pollution concentration value exceeds a preset threshold. i. The first calculation module receives the correction instruction and repeats steps c to f to make the output module output the corrected layered structure data and the corrected excavation volume of the corresponding merged soil layer.

[0014] The beneficial effects of this invention lie in that the arsenic-contaminated soil stratification and merging excavation planning system transforms the spatial distribution characteristics of pollution concentration into quantifiable merging decision parameters, and ensures that the merged soil layers remain within controllable limits in terms of environmental risk, remediation efficiency, and construction safety through rigid constraints. This arsenic-contaminated soil stratification and merging excavation planning system does not rely on improvements in remediation materials or chemical agents, but rather takes an engineering management approach, optimizing excavation logic to improve efficiency. It features strong universality, low implementation cost, and rapid results. This arsenic-contaminated soil stratification and merging excavation planning system is particularly suitable for large-area, deeply contaminated, and time-sensitive remediation projects, and can serve as a pre-optimization module for existing remediation technologies, significantly improving overall project benefits. Attached Figure Description

[0015] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the arsenic-contaminated soil stratification and merging excavation planning system according to an embodiment of the present invention.

[0016] Figure 2 This is a flowchart illustrating the stratified and combined excavation planning method for arsenic-contaminated soil according to an embodiment of the present invention.

[0017] Figure label: Get Module 1; Modeling Module 2; First calculation module 3; Update module 4; Second calculation module 5; Output module 6; Modify module 7. Detailed Implementation

[0018] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] Reference Figure 1 As shown, the present invention provides a stratified and merged excavation planning system for arsenic-contaminated soil, comprising: an acquisition module 1, a modeling module 2, a first calculation module 3, an update module 4, a second calculation module 5, and an output module 6.

[0021] Modeling module 2 is connected to acquisition module 1. First calculation module 3 is connected to modeling module 2. Update module 4 is connected to both modeling module 2 and first calculation module 3. Second calculation module 5 is connected to modeling module 2. Output module 6 is connected to modeling module 2.

[0022] Module 1 is used to acquire three-dimensional spatial data on the pollution concentration distribution of the arsenic-contaminated site to be remediated.

[0023] Modeling module 2 is used to construct a pollution concentration gradient field model based on pollution concentration distribution data, and is connected to acquisition module 1; The first calculation module 3 is used to determine adjacent soil layers one by one based on constraints using a greedy algorithm to output layered structure data.

[0024] The constraints include the pollution concentration gradient threshold, the soil layer thickness threshold, and the remediation target concentration threshold.

[0025] Specifically, the pollution concentration gradient threshold is the rate of change in arsenic concentration between adjacent soil layers to be merged.

[0026] The target concentration threshold for remediation is the overall average arsenic concentration of the soil layers to be merged.

[0027] The soil layer thickness threshold is the range of soil layer thicknesses to be merged.

[0028] The update module 4 is used to update the hierarchical structure data of the pollution concentration gradient field model and the pollution concentration distribution data corresponding to each merged soil layer based on the optimized sequence of merged soil layers.

[0029] The second calculation module 5 is used to calculate the excavation volume of each merged soil layer based on the updated pollution concentration gradient field model and layered structure data.

[0030] Output module 6 is used to output the layered structure data of the updated pollution concentration gradient field model and the corresponding excavation volume of the merged soil layers.

[0031] In a preferred embodiment, the arsenic-contaminated soil stratification and excavation planning system of the present invention further includes a correction module 7. The acquisition module 1 includes a first acquisition unit and a second acquisition unit.

[0032] The first acquisition unit is used to acquire three-dimensional spatial pollution concentration distribution data of the arsenic-contaminated site to be remediated.

[0033] The second acquisition unit is used to acquire the actual pollution concentration value at the bottom of each merged soil layer.

[0034] The second acquisition unit is connected to the correction module 7. The correction module 7 is connected to the modeling module 2 and the first calculation module 3.

[0035] After excavation of a merged soil layer, the correction module 7 compares the predicted and actual pollution concentration values ​​of the merged soil layer. When the difference between the actual and predicted pollution concentration values ​​exceeds a preset threshold, a correction instruction is generated. The first calculation module 3 receives the correction instruction and recalculates and outputs the layered structure data of the remaining soil layers.

[0036] Combination Figure 2 As shown, the present invention discloses a method for planning the stratified excavation of arsenic-contaminated soil using a stratified merging excavation planning system, comprising the following steps: a. Acquisition Module 1 acquires the three-dimensional spatial distribution data of the arsenic contaminated site to be remediated.

[0037] Specifically, before the acquisition module obtains pollution concentration distribution data, pollution concentration distribution data is obtained through on-site grid sampling and laboratory testing.

[0038] High-density grid sampling was used throughout the contaminated site to obtain spatial distribution data of arsenic concentration in vertical profiles. Sampling points were arranged at 20-centimeter intervals along the depth direction and at 50-square-meter intervals along the horizontal direction to ensure data coverage of the core contaminated area and transition zone. After sampling, the arsenic content at each point was determined by laboratory atomic fluorescence spectrometry.

[0039] b. Modeling module 2 constructs a pollution concentration gradient field model based on pollution concentration distribution data.

[0040] Based on the spatial distribution matrix of pollution concentration, a pollution concentration gradient field model is constructed to calculate the concentration gradient value between any two adjacent soil layers. The concentration gradient value in this invention is defined as the ratio of the difference in pollution concentration between two adjacent soil layers to the vertical distance between the layers.

[0041] The three-dimensional pollution concentration field model uses a geographic information system as a platform to bind the coordinates of each sampling point to its corresponding arsenic concentration value, forming a spatially interpolable continuous concentration field, which serves as the basic data source for subsequent hierarchical merging.

[0042] c. The first calculation module 3, based on constraints, uses a greedy algorithm to determine adjacent soil layers one by one to output layered structure data.

[0043] The constraints include a contamination concentration gradient threshold, a soil layer thickness threshold, and a remediation target concentration threshold. Specifically, the contamination concentration gradient threshold is the rate of change in arsenic concentration between adjacent soil layers to be merged. The remediation target concentration threshold is the overall average arsenic concentration of the soil layers to be merged. The soil layer thickness threshold is the range of soil layer thicknesses to be merged.

[0044] In this embodiment, multiple adjacent soil layers are combined to simultaneously satisfy the constraint conditions.

[0045] The first constraint is that the concentration gradient value of adjacent soil layers is less than or equal to the pollution concentration gradient threshold of this invention. The second constraint is that the total thickness of the merged soil layers is less than or equal to the soil layer thickness threshold of this invention. The third constraint is that the average contamination concentration of the merged soil layer is less than or equal to the remediation target concentration threshold of this invention.

[0046] The first calculation module repeatedly performs layer-by-layer scanning and merging judgment until all adjacent soil layers no longer meet the merging conditions, thus forming the final optimized layered structure data.

[0047] In this embodiment, the pollution concentration gradient threshold of the present invention is set to 0.5 mg / kg per meter, the soil layer thickness threshold of the present invention is set to 3 meters, and the remediation target concentration threshold of the present invention is set to no more than 20 mg of arsenic per kilogram of soil.

[0048] The pollution concentration gradient field model is constructed using the finite difference method. The spatial discrete grid step size is consistent with the sampling point spacing. The gradient calculation direction includes both vertical and horizontal directions, with priority given to merging judgments in the vertical direction.

[0049] The soil layer merging operation includes: merging adjacent soil layers that meet the constraints on the spatial coordinates, recalculating the weighted average pollution concentration of the merged soil layers, with the weighting coefficient being the proportion of the original soil layer volume to the total merged volume.

[0050] When calculating the average concentration of the combined soil layers, the volume-weighted average method is used, that is, the concentration of each sub-layer is multiplied by its corresponding volume, the sum is obtained, and then divided by the total volume to ensure that the calculation result reflects the true pollution load.

[0051] The three-dimensional spatial volume segmentation method of the present invention specifically includes: dividing each soil layer into several rectangular units on the horizontal projection plane, with the four corner points of each rectangular unit corresponding to different soil layer thickness values, calculating the earthwork volume of each rectangular unit using the truncated pyramid volume formula, and then summing all the rectangular units to obtain the total excavation volume of the soil layer.

[0052] Before performing soil layer merging judgment, the spatial distribution matrix of pollution concentration is smoothed, and a moving average filter is used to eliminate local sampling errors. The filter window size is a 3×3×3 cubic neighborhood.

[0053] The final optimized layered structure data of this invention includes the spatial boundary coordinates, average pollution concentration, volume parameters, and excavation priority identifier of each merged soil layer. The excavation priority identifier of this invention is generated according to the soil layer pollution concentration sorted from high to low.

[0054] In this embodiment, the first calculation module uses a dynamic excavation volume calculation model. The code for the calculation model is shown below: import numpy as np class ExcavationModel: "Dynamic Calculation Model for Excavation Volume" def __init__(self, contamination_data): """ Initialize the model parameter: contamination_data: A list of contamination data, each element containing... - depth: soil depth - thickness: Soil layer thickness - arsenic_concentration: Arsenic concentration """ self.contamination_data = sorted(contamination_data, key=lambda x: x['depth']) self.excavation_units = [] self.repair_target = None # Repair target concentration self.concentration_gradient_threshold = None # Concentration gradient threshold def set_constraints(self, repair_target, concentration_gradient_threshold): """Setting Constraints""" self.repair_target = repair_target self.concentration_gradient_threshold = concentration_gradient_threshold def _check_constraints(self, current_layer, next_layer): """ Check whether the three principles (constraints) of merging are met. parameter: current_layer: The current merged interval next_layer: The next layer to be merged return: bool: Whether all conditions are met """ if not self.repair_target or self.concentration_gradient_threshold isNone: raise ValueError("Please set constraints first") # 1. Check concentration gradient constraints gradient = abs(current_layer['avg_concentration'] - next_layer['arsenic_concentration']) if gradient>self.concentration_gradient_threshold: return False # 2. Check the constraints of the repair target (whether the repair requirements can still be met after merging). merged_concentration = (current_layer['total_concentration'] + next_layer['arsenic_concentration'] * next_layer['thickness']) / \ (current_layer['total_thickness'] + next_layer['thickness']) if merged_concentration>self.repair_target: return False # 3. Check the construction thickness constraints (the maximum thickness limit can be adjusted according to the actual situation). max_construction_thickness = 5.0 # Example value, can be adjusted according to actual needs. if current_layer['total_thickness'] + next_layer['thickness']>max_construction_thickness: return False return True def run(self): "Running the dynamic calculation model for excavation volume" if not self.contamination_data: return [] # Starting from the shallowest layer of pollution current_index = 0 total_layers = len(self.contamination_data) while current_index <total_layers: # Initialize the current merge interval start_layer = self.contamination_data[current_index] current_unit = { 'start_depth': start_layer['depth'], 'end_depth': start_layer['depth'] + start_layer['thickness'], 'total_thickness': start_layer['thickness'], 'total_concentration': start_layer['arsenic_concentration'] * start_layer['thickness'], 'avg_concentration': start_layer['arsenic_concentration'], 'layers_count': 1 } current_index += 1 # Try expanding downwards while current_index <total_layers: next_layer = self.contamination_data[current_index] # Check if all constraints are met if self._check_constraints(current_unit, next_layer): # If the conditions are met, merge the next level. current_unit['end_depth'] = next_layer['depth']+ next_layer['thickness'] current_unit['total_thickness'] += next_layer['thickness'] current_unit['total_concentration'] += next_layer['arsenic_concentration']* next_layer['thickness'] current_unit['avg_concentration'] = current_unit['total_concentration'] / current_unit['total_thickness'] current_unit['layers_count'] += 1 current_index += 1 else: # Conditions not met, terminate the extension. break # Calculate the volume (assuming the area is 1; in practical applications, it needs to be multiplied by the actual area). current_unit['volume'] = current_unit['total_thickness'] # Simplified calculation, actual value should be thickness × area # Determine if the repair objective is met current_unit['meets_repair_target'] = current_unit['avg_concentration']<= self.repair_target # Save the current excavation unit self.excavation_units.append(current_unit) return self.excavation_units # Usage Example if __name__ == "__main__": # Example contaminated data contamination_data = [ {'depth': 0.5, 'thickness': 0.3, 'arsenic_concentration': 12.5}, {'depth': 0.8, 'thickness': 0.4, 'arsenic_concentration': 13.2}, {'depth': 1.2, 'thickness': 0.3, 'arsenic_concentration': 18.7}, {'depth': 1.5, 'thickness': 0.5, 'arsenic_concentration': 22.3}, {'depth': 2.0, 'thickness': 0.4, 'arsenic_concentration': 15.6}, {'depth': 2.4, 'thickness': 0.6, 'arsenic_concentration': 14.1} ] # Create a model instance model = ExcavationModel(contamination_data) # Set constraints model.set_constraints(repair_target=20.0, concentration_gradient_threshold=5.0) # Running Model result = model.run() # Output Results print("Calculation results of excavation unit:") for i, unit in enumerate(result, 1): print(f"\nExcavation unit {i}:") print(f"Starting depth: {unit['start_depth']}m") print(f"Ending depth: {unit['end_depth']}m") print(f"Average arsenic concentration: {unit['avg_concentration']:.2f}") print(f"Volume: {unit['volume']:.2f}m³") print(f"Does the repair target meet the requirements: {'Yes' if unit['meets_repair_target'] else 'No'}") The dynamic excavation volume calculation model uses minimizing the total number of excavations as the objective function, and concentration gradient, remediation target, and construction thickness as constraints. It employs a greedy algorithm to expand the merging interval layer by layer, either upwards or downwards. During algorithm initialization, it starts from the shallowest contaminated layer and marks it as the current layer to be merged. Then, it probes the next adjacent layer downwards, checking whether all three constraints are satisfied. If satisfied, the next layer is included in the current merging interval, the average concentration and total thickness of the merged soil layer are updated, and the downward probe continues. If any constraint is not satisfied, the downward expansion terminates, the current merging interval is recorded as an independent excavation unit, and a new merging cycle begins with the next layer as the starting point. This process continues until the lowest contaminated layer is included in an excavation unit. The model output is a sequence of excavation units, each containing the starting depth, ending depth, average arsenic concentration, volumetric volume, and a determination indicator of whether the remediation target is met.

[0055] After generating the hierarchical data, the excavation units were prioritized based on site topography, transportation corridor layout, and remediation facility locations using a shortest path priority strategy. Units closest to transportation exits or remediation equipment entrances were excavated first to minimize earthwork transport distances. Units located on slopes or in high-risk areas were scheduled for construction only after weather conditions stabilized and support structures were complete, reducing safety risks. The actual construction of each excavation unit was carried out by a hydraulic backhoe excavator equipped with a BeiDou positioning system and tilt sensors to monitor excavation depth and slope angles in real time, ensuring consistency between the excavation boundaries and the model output. Excavated contaminated soil was loaded into leak-proof transport vehicles and transported to designated remediation areas according to unit labels to prevent mixing of soils with different contamination levels from affecting subsequent treatment outcomes.

[0056] d. Update module 4 updates the layered structure data of the pollution concentration gradient field model and the pollution concentration distribution data corresponding to each merged soil layer based on the merged soil layer optimization sequence.

[0057] e. The second calculation module 5 calculates the excavation volume of each merged soil layer based on the updated pollution concentration gradient field model and layered structure data.

[0058] The second calculation module uses a three-dimensional spatial volume segmentation method to calculate the excavation volume of each merged soil layer. Based on the soil layer boundary coordinates and thickness parameters, it performs accurate calculations using the polyhedral volume integral formula.

[0059] The excavation volume data is matched with the operating capacity parameters of the construction machinery to generate a phased excavation plan. The excavation volume of each phase does not exceed the maximum daily machinery processing capacity, and the excavation areas of adjacent phases maintain spatial continuity to avoid excessive local exposure of the foundation pit.

[0060] f. Output module 6 outputs the updated layered structure data of the pollution concentration gradient field model and the corresponding excavation volume of the merged soil layers.

[0061] In some embodiments, the arsenic contaminated soil stratification and merging excavation planning system further includes a correction module 7, and the arsenic contaminated soil stratification and merging excavation planning method further includes the following steps: g. Based on the layered structure data and excavation volume, each merged soil layer is excavated layer by layer from top to bottom. After the excavation of a merged soil layer, the second acquisition unit obtains the actual pollution concentration value at the bottom of each merged soil layer.

[0062] h. Correction module 7 compares the predicted and actual pollution concentration values ​​of a merged soil layer, and generates a correction instruction when the difference between the actual and predicted pollution concentration values ​​exceeds a preset threshold.

[0063] i. The first calculation module 3 receives the correction instruction and repeats steps c to f so that the output module 6 outputs the corrected layered structure data and the corrected excavation volume of the corresponding merged soil layer.

[0064] During the excavation process, the pollution concentration data of the excavation face is collected in real time and compared with the preset optimized layer structure. If the actual pollution concentration value deviates from the predicted value by more than 10%, the merging judgment and excavation volume calculation process is re-executed.

[0065] During earthwork excavation, a dynamic monitoring and correction mechanism is implemented simultaneously. After each excavation unit is completed, temporary monitoring points are immediately set up at the bottom of the merged soil layer to collect residual soil samples, measure the arsenic concentration, and compare it with the model's predicted value. If the measured concentration exceeds the model's predicted value by more than 10%, a correction procedure is triggered to recalculate the merging probability of adjacent unexcavated units, splitting the original merging interval or adjusting the remediation target parameters if necessary. If the measured concentration is lower than the predicted value and meets the remediation criteria, the merging threshold for subsequent units can be appropriately relaxed to accelerate the construction progress. This feedback mechanism ensures that the method maintains high accuracy and strong adaptability even under complex geological conditions.

[0066] To verify the effectiveness of the method, a field application was conducted at the site of a former chemical plant. The site covers approximately 8,000 square meters, with a maximum contamination depth of 6 meters and a highest arsenic concentration of 320 mg / kg soil. Traditional layered excavation methods, dividing the site into one-meter layers, would require six layers and a projected construction period of 45 days. Using this method, after concentration gradient analysis and screening based on three constraints, the excavation was ultimately consolidated into three units: Unit 1, depth 0-1.8 meters, average concentration 110 mg / kg; Unit 2, depth 1.8-4.2 meters, average concentration 320 mg / kg; and Unit 3, depth 4.2-6 meters, average concentration 290 mg / kg. All three units met the remediation target area and construction thickness constraints, reducing the total number of excavations by 50%, shortening the construction period to 28 days, reducing the pit exposure time by 40%, and achieving a 100% acceptance rate after remediation.

[0067] During the implementation of the method, special emphasis was placed on the rigor of data processing and the determinism of algorithm execution. All concentration data underwent outlier removal and spatial smoothing before being input into the model. The removal criterion was data points deviating from the local mean by more than three standard deviations. The smoothing method employed was a five-point moving average to ensure that the concentration field was free from abrupt noise interference with decision-making. When expanding and merging intervals, the greedy algorithm strictly followed an increasing depth order, without skipping or backtracking, ensuring the uniqueness and repeatability of the output sequence. Construction path planning did not introduce probabilistic selection; it relied solely on fixed geometric distances and risk levels for sorting, eliminating the influence of random factors on project progress.

[0068] The arsenic-contaminated soil stratification and merging excavation planning system of this invention transforms the spatial distribution characteristics of pollution concentration into quantifiable merging decision parameters, and ensures through rigid constraints that the merged soil layers remain within controllable ranges in terms of environmental risk, remediation efficiency, and construction safety. This system does not rely on improvements in remediation materials or chemical agents, but rather takes an engineering management approach, optimizing excavation logic to improve efficiency. It is characterized by strong applicability, low implementation cost, and rapid results. This system is particularly suitable for large-area, deeply contaminated, and time-sensitive remediation projects, and can serve as a pre-optimization module for existing remediation technologies, significantly improving overall project benefits.

[0069] Under extreme conditions, such as drastic fluctuations in concentration gradients or extremely narrow remediation target ranges, the arsenic contaminated soil stratification and excavation planning system of this invention can still maintain basic functionality by dynamically adjusting the merging threshold. When the concentration gradient in a certain area generally exceeds 0.5 mg / kg per meter, the gradient threshold can be temporarily relaxed to 80 mg / kg per meter, while the maximum thickness of a single layer can be reduced to 2 meters to balance merging efficiency and risk control. When the remediation target range narrows to below 15 mg / kg, the accuracy of the average concentration calculation is improved by re-interpolating data at 10-centimeter intervals to ensure that the weighted average result is unbiased. All such adjustments are completed within the methodological framework without changing the core algorithm structure.

[0070] The arsenic-contaminated soil stratified excavation planning system of this invention achieves scientific optimization of the stratified structure of arsenic-contaminated soil excavation by establishing a pollution concentration gradient field model and stratification merging constraints, avoiding ineffective excavation and resource waste caused by fixed thickness division in traditional stratified excavation. The system accurately calculates the excavation volume of each merged soil layer using a three-dimensional spatial volume segmentation method, providing a quantitative basis for construction machinery scheduling and foundation pit support design, significantly improving the feasibility and safety of the construction plan.

[0071] The dynamic correction mechanism proposed in the arsenic contaminated soil stratification and excavation planning system of this invention can adjust the stratification structure in real time based on on-site measured data, ensuring the accurate achievement of remediation goals and avoiding remediation deviations caused by changes in geological conditions or sampling errors.

[0072] This invention is applicable to the remediation of arsenic-contaminated sites in large-scale, complex terrains. It has high engineering adaptability and promotion value, fills the gap in the optimization of the excavation process in existing technologies, and realizes a technological leap from the research and development of remediation materials to the intelligent control of the construction process.

[0073] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A stratified and combined excavation planning system for arsenic-contaminated soil, characterized in that, include: Acquisition module for obtaining three-dimensional spatial pollution concentration distribution data of arsenic-contaminated sites to be remediated; A modeling module for constructing a pollution concentration gradient field model based on the pollution concentration distribution data is connected to the acquisition module; A first calculation module is used to determine adjacent soil layers one by one based on constraints using a greedy algorithm to output layered structure data. The constraints include a pollution concentration gradient threshold, a soil layer thickness threshold, and a remediation target concentration threshold. The first calculation module is connected to the modeling module. An update module for updating the hierarchical structure data of the pollution concentration gradient field model and the pollution concentration distribution data corresponding to each merged soil layer based on the merged soil layer optimization sequence is connected to the modeling module and the first calculation module. A second calculation module, connected to the modeling module, is used to calculate the excavation volume of each merged soil layer based on the updated pollution concentration gradient field model and hierarchical structure data. An output module for outputting the updated layered structure data of the pollution concentration gradient field model and the corresponding excavation volume of the merged soil layers is connected to the modeling module.

2. The stratified and combined excavation planning system for arsenic-contaminated soil according to claim 1, characterized in that, The pollution concentration gradient threshold is the rate of change in arsenic concentration between adjacent soil layers to be merged.

3. The stratified and combined excavation planning system for arsenic-contaminated soil according to claim 1, characterized in that, The target concentration threshold for remediation is the overall average arsenic concentration of the soil layers to be merged.

4. The stratified and combined excavation planning system for arsenic-contaminated soil according to claim 1, characterized in that, The soil layer thickness threshold is the range of soil layer thicknesses to be merged.

5. The stratified and combined excavation planning system for arsenic-contaminated soil according to claim 1, characterized in that, It also includes a correction module. The acquisition module includes a first acquisition unit for acquiring three-dimensional spatial pollution concentration distribution data of the arsenic-contaminated site to be remediated and a second acquisition unit for acquiring the actual pollution concentration value at the bottom of each merged soil layer. The second acquisition unit is connected to the correction module, and the correction module is connected to the modeling module and the first calculation module. After a combined soil layer is excavated, the correction module compares the predicted pollution concentration value of the combined soil layer with the actual pollution concentration value, and generates a correction command when the difference between the actual pollution concentration value and the predicted pollution concentration value exceeds a preset threshold. The first calculation module receives the correction instruction and recalculates and outputs the layered structure data of the remaining soil layers.

6. A method for planning the stratified excavation of arsenic-contaminated soil using the stratified excavation planning system for arsenic-contaminated soil as described in any one of claims 1 to 5, characterized in that, Includes the following steps: a. The acquisition module acquires the three-dimensional spatial distribution data of the arsenic contaminated site to be remediated; b. The modeling module constructs a pollution concentration gradient field model based on the pollution concentration distribution data; c. The first calculation module uses a greedy algorithm to determine adjacent soil layers one by one based on the constraints in order to output the layered structure data. d. The update module updates the layered structure data of the pollution concentration gradient field model and the pollution concentration distribution data corresponding to each merged soil layer based on the optimized sequence of the merged soil layers; e. The second calculation module calculates the excavation volume of each merged soil layer based on the updated pollution concentration gradient field model and layered structure data. f. The output module outputs the updated layered structure data of the pollution concentration gradient field model and the corresponding excavation volume of the merged soil layers.

7. The stratified and combined excavation planning system for arsenic-contaminated soil according to claim 6, characterized in that, The arsenic-contaminated soil stratified excavation planning system also includes a correction module, and the arsenic-contaminated soil stratified excavation planning method also includes the following steps: g. Based on the layered structure data and the excavation volume, each merged soil layer is excavated from top to bottom. After the excavation of a merged soil layer, the second acquisition unit acquires the actual pollution concentration value at the bottom of each merged soil layer. h. The correction module compares the predicted pollution concentration value of the merged soil layer with the actual pollution concentration value, and generates a correction instruction when the difference between the actual pollution concentration value and the predicted pollution concentration value exceeds a preset threshold. i. The first calculation module receives the correction instruction and repeats steps c to f to make the output module output the corrected layered structure data and the corrected excavation volume of the corresponding merged soil layer.

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