Performance evaluation method for partitioned water filtering channel of basement bottom plate

Abstract

The invention belongs to the technical field of constructional engineering, and particularly relates to a basement bottom plate partitioned water filtering channel performance evaluation method. The method comprises the following steps: firstly, based on geological conditions of a target project and basement structure parameters, establishing a three-dimensional seepage geometric model comprising a basement bottom plate and a surrounding soil layer; then, corresponding hydraulic parameters are given to all soil layer materials and water filtering channel materials in the model; then, setting at least two calculation working conditions and carrying out steady-state seepage calculation under different underground water level conditions; and finally, comparing and analyzing the evaluation indexes of different working conditions, evaluating the performance advantages of the partitioned water filtering channel compared with a traditional drainage mode, and carrying out parameter sensitivity analysis and parameter selection. According to the method, the drainage performance of the basement bottom plate can be remarkably improved, the maximum pore water pressure below the bottom plate is reduced, the average seepage speed is increased, the drainage efficiency is improved, and scientific basis and technical support are provided for waterproof drainage design of the basement.

Description

Technical Field

[0001] This invention belongs to the field of building engineering technology, specifically relating to a method for evaluating the performance of a partitioned water filtration channel in a basement floor slab. Background Technology

[0002] Large-scale development of underground spaces has led to increasingly massive basement projects, making the impact of groundwater on structures more prominent. Traditional basement floor drainage designs often employ perimeter blind drains, which can easily result in localized water accumulation and uneven water pressure distribution in large floor areas. This can cause localized stress concentration and even uplift damage to the floor. Zoned filtration channel technology, by setting multiple parallel or grid-like filtration channels under the floor, divides the large floor area into several drainage zones, achieving a more uniform water pressure distribution and more efficient drainage.

[0003] In the existing technology, most studies on drainage of basement floors focus on the optimization of traditional drainage methods. There are relatively few studies on the system performance evaluation of the new technology of zoned water filtration channels. The influence of design parameters such as zone spacing on system performance is still unclear, and the optimal design scheme needs to be determined through system numerical analysis. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and propose a performance evaluation method for partitioned water filtration channels in basement floor slabs. By combining numerical simulation technology, the method accurately simulates the seepage law and water pressure distribution characteristics under complex geological conditions, thereby determining the optimal design parameter range of partitioned water filtration channels and providing a new technical path and theoretical support for the waterproofing and drainage design of underground spaces.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] S1. Based on the geological conditions and basement structural parameters of the target project, establish a three-dimensional seepage geometric model including the basement floor slab and surrounding soil layers.

[0007] S2. Assign corresponding hydraulic parameters to each soil layer material and filter channel material in the geometric model described in step S1, and set the basement floor slab as an impermeable boundary to set the boundary conditions of the model.

[0008] S3. Set at least two calculation conditions, and perform steady-state seepage calculations for each condition under at least one groundwater level condition.

[0009] S4. Run numerical simulation calculations to solve the evaluation indicators under various working conditions, namely the water pressure distribution, seepage velocity and drainage efficiency under the bottom plate; by comparing and analyzing the evaluation indicators under different working conditions, evaluate the performance advantages of the zoned water filtration channel compared with the traditional drainage method.

[0010] Preferably, in the three-dimensional seepage geometry model described in step S1, a grid-like arrangement of partitioned water filtration channels is provided below the base plate.

[0011] Preferably, the boundary conditions of the model described in step S2 include an atmospheric pressure boundary on the top surface, an impermeable boundary on the bottom surface, and a constant head boundary on the side surface.

[0012] Preferably, the three-dimensional seepage geometry model described in step S1 uses structured mesh generation and local mesh refinement is performed near the water filtration channel to ensure the calculation accuracy in areas with large seepage gradients.

[0013] Preferably, the groundwater level conditions described in step S3 include three types: normal water level, design water level, and maximum water level.

[0014] Preferably, the calculation conditions in step S3 include:

[0015] Traditional perimeter drainage methods only involve setting up blind drainage ditches around the basement;

[0016] The zoned water filtration channel scheme arranges a grid-like channel according to the design plan.

[0017] Preferably, the hydraulic parameters in step S2 are determined based on the results of indoor infiltration tests and on-site pumping tests.

[0018] Preferably, the steady-state seepage calculation in step S3 is based on Darcy's law:

[0019] ;

[0020] In the formula: The seepage velocity; Permeability coefficient; For water head; The distance is in the seepage direction; the continuity equation is:

[0021] ;

[0022] In the formula: , respectively, are the permeability coefficients in the x, y, and z directions.

[0023] Preferably, the method of the present invention further includes performing parameter sensitivity analysis, setting different combinations of values ​​for the partition spacing and channel size of the partitioned water filtration channel to carry out steady-state seepage calculations, and then determining the recommended parameter value range or combination.

[0024] Finally, this invention also proposes a performance evaluation system for a partitioned water filtration channel in a basement floor slab, comprising the following modules:

[0025] The modeling module is configured to perform the following process: based on the geological conditions and basement structural parameters of the target project, establish a three-dimensional seepage geometry model including the basement floor and surrounding soil layers;

[0026] The parameter and condition setting module is configured to perform the following process: assign corresponding hydraulic parameters to the soil material and filter channel material in the geometric model, set the basement floor as an impermeable boundary, and set the boundary conditions of the model.

[0027] The steady-state seepage calculation module is configured to perform the following process: set at least two calculation cases, each of which performs steady-state seepage calculations under at least one groundwater level condition;

[0028] The evaluation module is configured to perform the following processes: run numerical simulation calculations to solve for evaluation indicators under various working conditions, namely water pressure distribution, seepage velocity and drainage efficiency under the base plate; and evaluate the performance advantages of the zoned filtration channel compared with traditional drainage methods by comparing and analyzing the evaluation indicators under different working conditions.

[0029] The method for evaluating the performance of a zoned filtration channel in a basement floor slab, as described in this invention, has the following technical advantages compared to existing technologies:

[0030] (1) Under the same geological and water level conditions, the method of the present invention establishes a three-dimensional steady-state seepage model of “basement floor slab - surrounding soil layer - zoned water filtration channel” and solves it using Darcy’s law. This can significantly reduce the maximum pore water pressure under the floor slab. Compared with the traditional scheme of only drainage around the perimeter, it can effectively alleviate the accumulation of water pressure in the middle of the floor slab and reduce the risk of floating and leakage.

[0031] (2) The evaluation method described in this invention determines the optimal design parameter range of the partitioned water filtration channel based on numerical simulation analysis. The parameter combination can control the project cost while ensuring good drainage effect, and achieve the best technical and economic balance, providing a new technical path and theoretical support for the waterproof and drainage design of underground space. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0033] Figure 1 The present invention relates to a flowchart of a method for evaluating the performance of a partitioned water filtration channel in a basement floor slab.

[0034] Figure 2 This is a comparison diagram of the water pressure distribution on the bottom plate under different drainage schemes in embodiments of the present invention.

[0035] Figure 3This is a diagram showing the seepage velocity distribution of the partitioned water filtration channel in an embodiment of the present invention.

[0036] Figure 4 This is a schematic diagram illustrating the effect of partition spacing on drainage efficiency in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] Example 1: This example uses a large underground commercial complex in a coastal city as the engineering background. The burial depth is 7.2m, the bottom slab thickness is 0.8m, the groundwater level is high, the annual water level is about 2.5m deep, and the water level can rise to 1.8m below the ground during the high-water season. The strata are mainly composed of fill soil, silty clay, fine sand layer and strongly weathered rock, among which the fine sand layer is the main aquifer with a permeability coefficient of 8.5×10⁻ 4 m / s. The site strata are divided into four layers from top to bottom: artificial fill with a thickness of 3.2m and a permeability coefficient of 5.2×10⁻ 5 m / s; silty clay thickness 2.8m, permeability coefficient 2.1×10⁻ 6 m / s; fine sand layer thickness 4.5m, permeability coefficient 8.5×10⁻ 4 m / s; the bottom is strongly weathered granite with a permeability coefficient of 1.8×10⁻ 7 The groundwater speed is m / s, mainly found in fine sand layers, with an annual water level fluctuation of approximately 1.2 m and a pH value of 7.2-7.8. (Reference) Figure 1 The specific process is as follows:

[0039] (1) Geometric model construction:

[0040] A three-dimensional numerical model was established based on the actual engineering situation. The model dimensions are 300m × 200m × 15m, covering the basement floor and a certain range of surrounding soil layers. The basement floor, located in the center of the model, measures 180m × 120m with a depth of 7.2m. The zoned filtration channels are arranged in a grid pattern with a longitudinal spacing of 10m and a transverse spacing of 12m. The channel width is 0.7m and the depth is 0.5m, with a total of 21 filtration channels. The model uses structured mesh generation, with localized mesh refinement near the filtration channels to ensure the calculation accuracy in areas with large seepage gradients. The entire model is divided into approximately 1.8 million hexahedral elements. Mesh quality checks show a skewness of less than 0.3, meeting the calculation requirements. Boundary conditions are set as follows: the top surface is an atmospheric pressure boundary, the bottom surface is an impermeable boundary, and the sides are constant head boundaries, simulating lateral groundwater recharge.

[0041] (2) Material parameter setting:

[0042] The hydraulic parameters of each soil layer in the numerical simulation were determined based on the results of indoor permeability tests and field pumping tests. The filter channel material was graded crushed stone with a permeability coefficient of 8.2 × 10⁻² m / s and a porosity of 0.45. The basement floor slab was made of C30 concrete and was set as an impermeable boundary in the model. Seepage calculations were based on Darcy's law.

[0043]

[0044] In the formula: The seepage velocity; Permeability coefficient; For water head; Let be the distance in the seepage direction. The continuity equation is:

[0045]

[0046] In the formula: , respectively, are the permeability coefficients in the x, y, and z directions.

[0047] (3) Calculation of operating conditions:

[0048] To comprehensively evaluate the performance of the zoned water filtration channel, multiple calculation scenarios were set up for comparative analysis. Scenario 1 is the traditional perimeter drainage method, with drainage blind ditches only installed around the basement; Scenario 2 is the zoned water filtration channel scheme, with a grid-like channel layout according to the design plan. Each scenario considers different groundwater levels, setting three hydrological conditions: normal water level (2.5m depth), design water level (2.0m depth), and highest water level (1.8m depth). The calculations employed steady-state seepage analysis, focusing on key indicators such as water pressure distribution below the foundation slab, seepage velocity field, and drainage efficiency. By comparing the calculation results of different schemes, the performance advantages of the zoned water filtration channel were quantitatively analyzed.

[0049] (4) Evaluation and analysis:

[0050] Numerical simulation results show that under traditional peripheral drainage methods, the water pressure in the central area of ​​the foundation slab is significantly higher than that in the surrounding areas, reaching a maximum of 78.5 kPa. The water pressure distribution shows a decreasing trend from the center to the perimeter. This uneven distribution easily leads to localized stress concentration in the central area of ​​the foundation slab. The zoned filtration channel scheme significantly improves the water pressure distribution under the foundation slab, reducing the maximum water pressure to 54.0 kPa, a reduction of 31.2%. By setting up a grid-like filtration channel, the originally continuous large-area foundation slab is divided into multiple relatively independent drainage units, resulting in a more uniform water pressure distribution. Figure 2 As shown, the distribution of isobars in the partitioned filtration channel scheme is more dense and uniform, and the water pressure value in the central area of ​​the bottom plate is reduced by 35%-40% compared with the traditional scheme.

[0051] The seepage velocity field analysis results further validated the superiority of the zoned filtration channels. Under the traditional perimeter drainage scheme, the seepage velocity is relatively small in the central area of ​​the foundation slab, only 0.8 × 10⁻⁻⁻⁶. 5 m / s - 1.2 × 10⁻ 5 The speed gradually increases towards the periphery to 2.8 × 10⁻ m / s. 5 The flow rate is m / s, which makes it difficult for groundwater in the central area of ​​the foundation to drain in a timely manner. The zoned filtration channel scheme effectively improves the overall seepage velocity by shortening the seepage path. The seepage velocity in each area below the foundation is relatively uniform, with an average value of 2.1×10⁻ 5 m / s, an improvement of approximately 40% compared to traditional methods. For example... Figure 3 As shown, the seepage direction under the zoned scheme is more orderly, and the water flow in each drainage zone can smoothly flow into the nearest filter channel, increasing the drainage volume per unit time by 24.6% compared with the traditional scheme.

[0052] Drainage efficiency, as a core indicator for evaluating the performance of a drainage system, quantifies the drainage capacity of different schemes by calculating the drainage volume per unit area of ​​the foundation slab. The drainage efficiency of traditional perimeter drainage schemes is 3.2 × 10⁻⁻⁻⁶. 6 The drainage efficiency in the central area of ​​the foundation slab is particularly low, at only 1.8 × 10⁻ m³ / (m²·s). 6 m³ / (m²·s). The drainage efficiency of the zoned filtration channel scheme reaches 4.0×10⁻ 6 The efficiency was increased by 24.6% to m³ / (m²·s). The differences in drainage efficiency between different drainage zones were significantly reduced, with the ratio of the highest efficiency zone to the lowest efficiency zone decreasing from 2.1:1 in the traditional scheme to 1.3:1, demonstrating good drainage uniformity. The drainage efficiency comparison data shown in Table 1 clearly reflects the significant advantages of the zoned filtration channel in improving drainage performance.

[0053] Table 1

[0054]

[0055] In addition, parameter sensitivity analysis was conducted on different schemes, and steady-state seepage calculations were carried out with different combinations of values ​​for the partition spacing and channel size of the partitioned water filtration channel to determine the recommended parameter value range or combination.

[0056] The spacing between zones, a key parameter in the design of zoned filtration channels, directly affects drainage efficiency and project cost. A comparative analysis was conducted using five different zone spacings: 6m, 8m, 10m, 12m, and 15m. Calculations show that as the zone spacing decreases, the maximum water pressure on the bottom slab decreases linearly, from 62.3 kPa at a 15m spacing to 48.7 kPa at a 6m spacing. This trend follows the distance effect principle in seepage theory; shortening the seepage distance directly reduces head loss, thus reducing the water pressure load on the bottom slab. The zone spacing has a more significant impact on drainage efficiency. Reducing the spacing from 15m to 6m increases drainage efficiency by 42%. Drainage efficiency is inversely proportional to the zone spacing. The most significant increase (25%) occurs when the spacing decreases from 15m to 10m; further reduction to 8m results in a 15% increase; and the marginal effect diminishes when the spacing decreases to 6m, with only a 2% increase.

[0057] like Figure 4 As shown in the figure, cost-benefit analysis reveals that a zoning spacing of 8m-12m can control project costs while ensuring good drainage performance. When the zoning spacing exceeds 15m, high water pressure concentration reappears in the central area of ​​the foundation slab; when the spacing is less than 6m, the mutual influence between adjacent filter channels increases, and the marginal drainage efficiency decreases. Considering both drainage performance and economy, a zoning spacing of 8m-12m is recommended, which can improve drainage efficiency by 30%-35% and control the increase in project cost to 20%-30%.

[0058] The width and depth of the filtration channel are important geometric parameters affecting its water-conducting capacity. By analyzing the impact of different size combinations on drainage performance, the calculation results show that the channel width has a logarithmic relationship with the drainage effect. When the width increases from 0.4m to 0.6m, the drainage efficiency improves by 18%, but the improvement decreases to 12% when the width continues to increase to 0.8m. The channel depth has a relatively smaller impact; increasing the depth from 0.3m to 0.5m improves the drainage efficiency by 15%, and the improvement is only 9% when the depth continues to increase to 0.7m. As shown in Table 2, considering construction convenience and economy, it is recommended that the channel width be controlled between 0.6m and 0.8m, and the depth around 0.5m, which can ensure good drainage effect while avoiding excessive investment. The optimization of channel size needs to be determined in conjunction with specific geological conditions and groundwater level fluctuations.

[0059] Table 2

[0060]

[0061] As demonstrated in the examples, the zoned filtration channel has significant technical advantages over traditional peripheral drainage methods. It can effectively reduce the water pressure load on the foundation slab, with a maximum water pressure reduction of 31.2%, while improving drainage efficiency by 24.6%. This significantly improves the stress state and drainage conditions of the foundation slab. The grid-like arrangement of the filtration channels allows for the discharge of groundwater nearby, shortening the seepage path, increasing the seepage velocity, and making the water pressure distribution below the foundation slab more uniform. Numerical simulation analysis determines the optimal design parameter range for the zoned filtration channel. The parameter combination can control project costs while ensuring good drainage performance, achieving an optimal balance between technology and economy, and providing a new technical path and theoretical support for the waterproofing and drainage design of underground spaces.

[0062] Example 2: This example proposes a performance evaluation system for a zoned filtration channel in a basement floor slab, characterized in that the system includes:

[0063] The modeling module is configured to perform the following process: based on the geological conditions and basement structural parameters of the target project, establish a three-dimensional seepage geometry model including the basement floor and surrounding soil layers;

[0064] The parameter and condition setting module is configured to perform the following process: assign corresponding hydraulic parameters to the soil material and filter channel material in the geometric model, set the basement floor as an impermeable boundary, and set the boundary conditions of the model.

[0065] The steady-state seepage calculation module is configured to perform the following process: set at least two calculation cases, each of which performs steady-state seepage calculations under at least one groundwater level condition;

[0066] The evaluation module is configured to perform the following processes: run numerical simulation calculations to solve for evaluation indicators under various working conditions, namely water pressure distribution, seepage velocity and drainage efficiency under the base plate; and evaluate the performance advantages of the zoned filtration channel compared with traditional drainage methods by comparing and analyzing the evaluation indicators under different working conditions.

[0067] It should be noted that the processing flow of Embodiment 2 corresponds to the specific steps of the method provided in Embodiment 1 of the present invention, and has the corresponding functional modules and beneficial effects of the method. Technical details not described in detail in this embodiment can be found in the method provided in Embodiment 1 of the present invention.

[0068] The specific implementation schemes described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific implementation schemes of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for evaluating the performance of a zoned water filtration channel in a basement floor slab, characterized in that, The method comprises the following steps: S1, based on the geological conditions of the target project and the basement structure parameters, a three-dimensional seepage geometric model containing the basement floor and the surrounding soil layers is established; S2, the corresponding hydraulic parameters are assigned to each soil layer material and filter channel material in the geometric model described in step S1, and the basement floor is set as an impermeable boundary, and the boundary conditions of the model are set; S3, at least two calculation conditions are set, and each condition is under at least one groundwater level condition for steady-state seepage calculation; S4, numerical simulation calculation is performed to solve the evaluation indexes under each condition, i.e. the water pressure distribution, seepage velocity and drainage efficiency under the floor; by comparing and analyzing the evaluation indexes of different conditions, the performance advantages of the partitioned filter channel compared with the traditional drainage method are evaluated.

2. The method of claim 1, wherein, In the three-dimensional seepage geometric model described in step S1, a partitioned filter channel arranged in a grid is provided under the floor.

3. The method of claim 2, wherein, The boundary conditions of the model described in step S2 include an atmospheric pressure boundary on the top surface, an impermeable boundary on the bottom surface, and a constant water head boundary on the side surface.

4. The method of claim 2, wherein, The three-dimensional seepage geometric model described in step S1 is divided by structured grid, and local encryption processing is performed near the filter channel to ensure the calculation accuracy of the area with large seepage gradient.

5. The method of claim 1, wherein, The groundwater level conditions described in step S3 include three conditions: constant water level, design water level and highest water level.

6. The method of claim 1, wherein, The calculation conditions described in step S3 include: Traditional peripheral drainage method, only drainage blind ditch is arranged around the basement; Partitioned filter channel scheme, grid channels are arranged according to the design scheme.

7. The method of claim 1, wherein, The hydraulic parameters described in step S2 are determined according to the results of indoor permeation test and field pumping test.

8. The method of claim 1, wherein, The steady-state seepage calculation described in step S3 is based on Darcy's law: ； wherein: is the seepage velocity; is the permeability coefficient; is the water head; is the distance in the seepage direction; and the continuity equation is: ； wherein: are the permeability coefficients in the x, y and z directions, respectively.

9. The method of claim 1, wherein, The method further comprises parameter sensitivity analysis, different value combinations of the partitioned filter channel partition distance and channel size are set to carry out steady-state seepage calculation, and then the recommended parameter value range or combination is determined.

10. A basement floor zoned underdrain performance evaluation system characterized by, The system comprises: A modeling module configured to perform the following process: based on the geological conditions of the target project and the basement structure parameters, a three-dimensional seepage geometric model containing the basement floor and the surrounding soil layers is established; A parameter and condition setting module configured to perform the following process: the corresponding hydraulic parameters are assigned to each soil layer material and filter channel material in the geometric model, and the basement floor is set as an impermeable boundary, and the boundary conditions of the model are set; A steady-state seepage calculation module configured to perform the following process: at least two calculation conditions are set, and each condition is under at least one groundwater level condition for steady-state seepage calculation; An evaluation module configured to perform the following process: numerical simulation calculation is performed to solve the evaluation indexes under each condition, i.e. the water pressure distribution, seepage velocity and drainage efficiency under the floor; by comparing and analyzing the evaluation indexes of different conditions, the performance advantages of the partitioned filter channel compared with the traditional drainage method are evaluated.

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