BIM-based anti-floating anchor construction method and system

Abstract

The invention discloses an anti-floating anchor rod construction method and system based on BIM, and relates to building construction. The method comprises the steps that an initial waterproof node design scheme of a prestressed anti-floating anchor rod is obtained, and a BIM model of the prestressed anti-floating anchor rod is established; simulating water seepage conditions of the prestressed anti-floating anchor rod under different underground water pressure conditions by using a BIM model, and identifying a potential water leakage channel; carrying out different blocking treatments on the identified potential water leakage channel, including blocking the first water leakage channel by adopting an expansion water stop strip; the second water leakage channel is blocked through non-cured asphalt; for the third water leakage channel, a water stop wing ring is welded to the outer side of the steel sleeve for blocking; the fourth water leakage channel is blocked through non-cured asphalt; setting corresponding plugging measures in the BIM model to obtain a BIM model containing the plugging measures; and a waterproof node construction drawing is generated by using the BIM model containing the plugging measures, and field construction is guided. The underground engineering leakage risk is effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of building construction, and in particular to a BIM-based anti-floating anchor construction method and system. Background Art

[0002] The waterproofing system of prestressed anti-floating anchors is uniquely complex. Unlike conventional waterproofing projects, the anchors must penetrate the entire underground structure, forming a continuous channel from the bedrock to the top of the raft. This characteristic leads to four waterproofing challenges:

[0003] First, the diversity and concealment of seepage paths. Groundwater can infiltrate through a variety of pathways: along the inside of prestressed steel bars, along the outside of the bars, through the raft slab, and through the flexible waterproofing layer. These pathways are intertwined, and under varying groundwater pressures, the dominant seepage path may shift, making traditional single-step waterproofing measures inadequate for a comprehensive response.

[0004] Second, the heterogeneity of the connection interface. Anti-floating anchors involve multiple material interfaces: the rod body and bedrock, the rod body and cushion layer, the prestressed steel bar and grouting, the flexible waterproofing layer and prestressed steel bar, and the steel casing and raft slab. The permeability characteristics of each interface vary significantly, and heterogeneous features such as irregular distribution of construction joints, local variations in grouting density, and spatial variations in interface roughness can be observed. Traditional homogeneous seepage theory cannot accurately describe this complex seepage behavior.

[0005] Third, the dynamics of groundwater pressure. Groundwater pressure varies dynamically with factors such as season, rainfall, and groundwater level. Under normal operating conditions, it may be 0.3-0.5 MPa, while under extreme conditions, it can reach 0.8-1.0 MPa. Under different pressure conditions, the dominant mechanisms and paths of seepage can be completely different, necessitating detailed analysis based on different operating conditions.

[0006] Fourth, waterproofing measures lack specificity. Existing technologies typically employ uniform waterproofing standards and measures, failing to adopt differentiated sealing strategies tailored to the characteristics of different leakage paths. For example, for water seepage along minute cracks inside prestressed steel bars, expansion waterstops are required; for surface water seepage outside the bars, flexible materials such as non-solidified asphalt are required.

[0007] Existing design methods primarily rely on two-dimensional drawings and simplified calculations, failing to accurately simulate the complex seepage processes in three-dimensional space. Construction personnel struggle to intuitively understand potential leakage paths, let alone predict the risk of seepage under different working conditions. This results in waterproofing designs being out of sync with actual needs, leading to either inadequate waterproofing leading to leakage or excessive waterproofing resulting in waste.

[0008] Therefore, there is an urgent need for a technical method that can accurately identify multiple potential leakage channels under different groundwater pressure conditions to achieve precise design and construction guidance of prestressed anti-floating anchor waterproofing systems. Summary of the Invention

[0009] In view of the difficulty in accurately identifying various potential leakage channels under different groundwater pressure conditions during the construction of prestressed anti-floating anchor rods, this application provides a BIM-based anti-floating anchor rod construction method and system, establishes a BIM model and integrates CFD fluid dynamics analysis, accurately simulates the seepage path of groundwater in the anchor rod waterproofing system, identifies four typical leakage channels and takes corresponding targeted blocking measures, effectively reducing the leakage risk of underground projects.

[0010] One aspect of the present application provides a BIM-based anti-floating anchor construction method, including: S1, obtaining an initial waterproof node design scheme for prestressed anti-floating anchors, the waterproof nodes including tensioning part waterproof nodes and anchor head waterproof nodes; S2, establishing a BIM model of the prestressed anti-floating anchor according to the initial waterproof node design scheme; S3, using the BIM model to simulate the seepage of the prestressed anti-floating anchor under different groundwater pressure conditions, and identifying potential leakage channels.

[0011] S4. Based on the simulation results, different plugging treatments are applied to the identified potential leakage channels, including: the first leakage channel, where groundwater passes through the bottom of the rod along the inner side of the prestressed steel bar to reach the anchor head, is plugged with an expansion waterstop strip; the second leakage channel, where groundwater passes through the rod and cushion along the outer side of the rod to reach the anchor head, is plugged with non-solidifying asphalt; the third leakage channel, where groundwater passes through the rod inside the raft slab and penetrates the raft slab to reach the anchor head, is plugged by welding a waterstop ring on the outer side of the steel casing; the fourth leakage channel, where groundwater passes through the junction of the flexible waterproof layer and the prestressed steel bar along the prestressed steel bar to reach the anchor head, is plugged with non-solidifying asphalt;

[0012] S5, setting corresponding blocking measures in the BIM model to obtain a BIM model including the blocking measures; S6, using the BIM model including the blocking measures to generate waterproof node construction drawings to guide on-site construction.

[0013] The first leakage channel reflects groundwater entering from the base of the anchor bolt (the bedrock anchorage), seeping upward along the tiny gap between the prestressed steel and the grouting, and ultimately reaching the anchor head at the top of the raft. During anchor bolt construction, achieving a completely tight bond between the prestressed steel and the grouting is difficult. This is especially true when the steel is rusted, oily, or the grouting is insufficiently vibrated, resulting in the formation of continuous capillary channels. Although these channels are extremely fine (typically less than 0.1 mm), they can still form stable seepage pathways under the influence of groundwater pressure.

[0014] The second leakage path reflects groundwater entering through the interface between the anchor rod and the surrounding soil (or bedrock), percolating upward along the rod's outer surface, passing through the contact interface between the cushion layer and the rod, and continuing to rise along the outside of the rod, ultimately bypassing the waterproofing structure and reaching the anchor head. During grouting after the anchor hole is drilled, irregularities such as collapse and overexcavation may occur in the hole wall, resulting in gaps between the grout and the hole wall. Furthermore, shrinkage of the grout during solidification can also form annular gaps on the outside of the rod. These gaps can further widen in the cushion layer due to improper joint management during construction.

[0015] The third leakage channel reflects groundwater flowing directly through the entire thickness of the raft slab, either along the contact surface between the anchor rod and the raft concrete or through the construction gap between the steel casing and the raft slab. This creates a vertical, upward seepage channel within the raft slab, ultimately seeping out onto the raft surface near the anchor head. Steel casing is embedded where the anchor rod passes through the raft slab, and the interface between the steel casing and the raft concrete is a natural weak link. Improper surface treatment of the steel casing, insufficient vibration during concrete pouring, or slight displacement of the steel casing during the concrete hardening process can all lead to the formation of a continuous crack at this interface.

[0016] The fourth leakage path reflects groundwater first reaching the flexible waterproof layer at the bottom of the raft slab. It then enters through the junction between the flexible waterproof layer and the prestressed steel bars (i.e., the point where the waterproof layer is penetrated by the steel bars), seeping upward along the gap between the steel bars and the waterproof layer, ultimately reaching the anchor head. Flexible waterproof layers (such as waterproof membranes or coatings) require special treatment at locations where prestressed steel bars pass through. However, due to the significant material differences between the steel bars and the flexible material, resulting in different coefficients of thermal expansion and contraction, coupled with improper sealing during construction, this junction is prone to forming a weak point for water seepage. In particular, slight movement during the steel bar tensioning process can further compromise the seal at this location.

[0017] Furthermore, the waterproof nodes of the tensioning part are treated with the waterproof nodes tensioned on the raft slab; the waterproof nodes of the anchor heads are treated with steel plate welding and sealing. Among them, the waterproof nodes of the tensioning part refer to the waterproof structure set up in the area where the prestressed anti-floating anchor rods are prestressed on the top surface of the raft slab for tensioning operations, mainly including the tensioning end anchor, the pressure plate, the tensioning operation space and the waterproof treatment measures around it. Located on the upper surface of the raft slab, it is the working area where the prestressed steel bars pass through the raft slab and are tensioned and locked. After the tensioning operation is completed, the area needs to be reliably waterproofed and sealed to prevent surface water, rainwater or construction water from seeping into the anchor rod system from this weak part. The raft slab is cast first, then the tensioning operation is carried out, and finally the waterproof closure is carried out, which avoids the difficulty of tensioning in the narrow space under the raft slab.

[0018] The anchor head waterproofing joint refers to the junction between the fixed end of the prestressed anti-floating anchor (i.e., the bottom end anchored in the bedrock), the grouting body, and the surrounding rock. It also includes a waterproofing structure installed in this area to prevent groundwater from migrating up the anchor. Located at the bottom of the anchor, at the end of the anchoring section deep into the bedrock, it serves as the first line of defense against groundwater infiltration into the anchor system, preventing groundwater from entering from the bottom of the anchor and seeping upward along the anchor.

[0019] Furthermore, S3 uses the BIM model to simulate the seepage of prestressed anti-floating anchor rods under different groundwater pressure conditions and identify potential leakage channels, including: setting groundwater pressure parameters in the BIM model, the groundwater pressure parameters include normal working pressure and extreme working pressure; establishing connection surfaces between the components of the prestressed anti-floating anchor rods in the BIM model, the connection surfaces include: the contact surface between the rod body and the bedrock, the contact surface between the rod body and the cushion layer, the contact surface between the prestressed steel bar and the grouting body, the contact surface between the flexible waterproof layer and the prestressed steel bar, and the contact surface between the steel casing and the raft slab; under the action of the groundwater pressure parameters, the permeability coefficient of groundwater through each connection surface is calculated through the BIM model, and when the permeability coefficient is greater than the preset threshold, the corresponding connection surface is determined to be a potential seepage interface; based on the potential seepage interface, the seepage path of groundwater is simulated through the BIM model; according to the starting position and flow direction of the seepage path, the potential leakage channels are divided into the first to fourth leakage channels.

[0020] Furthermore, the normal operating pressure is 0.3MPa to 0.5MPa; the extreme operating pressure is 0.8MPa to 1MPa.

[0021] Furthermore, under the action of groundwater pressure parameters, the permeability coefficient of groundwater through each connection surface is calculated through the BIM model. When the permeability coefficient is greater than the preset threshold, the corresponding connection surface is determined to be a potential seepage interface, including: according to the geometric shape and size of the connection interface, an adaptive grid division algorithm is used to divide the interface into n×m rectangular sub-areas; for each sub-area, corresponding local material property parameters are set respectively, and the local material property parameters include: construction gap distribution density coefficient α, with a value range of 0.1-1.0; grouting density coefficient β, with a value range of 0.7-1.0; interface roughness coefficient γ, with a value range of 1.0-3.0.

[0022] The local permeability coefficient of each sub-area is calculated using the modified Darcy's law and the equivalent permeability coefficient of the corresponding connection interface ; ,in, is the area of ​​the ith subregion, is the weight coefficient, , is the maximum permeability coefficient in all sub-areas; in particular, the traditional Darcy law uses a simple arithmetic average or area-weighted average to calculate the equivalent permeability coefficient. The traditional algorithm is: This method suffers from the "average value trap"—when 99% of the interface has a low permeability coefficient and only 1% has high permeability due to construction defects, the average permeability calculated by the traditional method is still low, leading to the erroneous conclusion that the interface waterproofing performance is good. However, in actual projects, it is precisely this 1% of high permeability area that creates a dominant seepage channel, causing the entire waterproofing system to fail.

[0023] In the actual seepage process, groundwater will automatically seek the path with the least resistance, and the actual seepage volume in the high permeability area far exceeds its area ratio. This makes the contribution of the high permeability sub-region in the calculation of the equivalent permeability coefficient increase quadratically ( becomes ), which accurately reflects the physical nature of seepage.

[0024] , where Q is the seepage rate per unit time, L is the seepage path length, and ΔP is the pressure difference; in particular, the permeability coefficient calculation formula of the traditional Darcy law is Based on the assumption of homogeneous medium, the entire connection interface is regarded as an ideal state with uniform material properties. This is seriously out of touch with the actual construction situation of anti-floating anchor rods - factors such as uneven vibration during grouting, water stratification, and steel bar obstruction may cause the permeability of different positions on the same interface to differ by 2 to 3 orders of magnitude. Traditional methods are unable to identify and quantify this spatial variability in construction quality, resulting in missed judgments in high-risk areas. This application introduces a heterogeneous correction factor based on the traditional formula. , construction gap density α: directly reflects the degree of construction defects in the sub-area, grouting density β: quantitatively characterizes the local differences in grouting quality, and interface roughness γ: considers the quality of construction interface treatment.

[0025] When the local permeability Greater than , identify "point-like" leakage hazards, even if the high permeability area is small, it can be accurately captured; or equivalent permeability coefficient Greater than When the water level reaches 0.05, the corresponding connection interface is determined to be a potential water seepage interface; the "surface" leakage risk is assessed to prevent overall leakage caused by the superposition of multiple medium permeability areas.

[0026] In summary, the interface between prestressed anti-floating anchors (such as the anchor body and grouting, or between prestressed steel and grouting) is not a homogeneous porous medium. Instead, it exhibits irregular distribution of construction joints, local variations in grouting density, and spatial variations in interface roughness. However, Darcy's law assumes a homogeneous medium and cannot accurately reflect the actual seepage characteristics of such a heterogeneous interface. This application divides the interface into multiple subregions; calculates the permeability coefficient for each subregion; considers the differences between different regions; and comprehensively assesses the seepage risk of the entire interface.

[0027] Furthermore, based on the potential seepage interface, the groundwater seepage path is simulated through the BIM model, including: integrating the computational fluid dynamics (CFD) module into the BIM model; setting the groundwater inlet boundary conditions: combining the local permeability coefficient with the groundwater inlet boundary conditions; Greater than The area is set as the main inlet, and the equivalent permeability coefficient Greater than A secondary inlet is set in the area and the anchor head position is set as the outlet boundary. According to the set groundwater pressure parameters, the corresponding working pressure is applied at the inlet boundary condition.

[0028] The computational fluid dynamics (CFD) module is used to solve the groundwater velocity field and pressure field distribution based on the Darcy-Brinkman equation. According to the velocity field and pressure field distribution, the particle tracking method is used to track the streamlines and obtain the seepage path of groundwater from each potential seepage surface to the anchor head. The method includes: setting the tracer particle release point on the determined potential seepage interface, where: the local permeability coefficient is 0. Greater than The main release points are set at the center of the sub-area with a spacing of 0.1m; Greater than Secondary release points are set on the connection interface with a spacing of 0.2m;

[0029] Velocity field calculated based on CFD module , use the Lagrangian method to solve the particle motion trajectory: ; ; ;in, is the particle position coordinate, t is the time, and the fourth-order Runge-Kutta method is used for numerical integration;

[0030] Record the complete trajectory data of each tracer particle from the release point to the anchor head outlet, including: the spatial coordinate sequence of the particle ; The corresponding time series ;Sequence of pressure values ​​at the passing position and velocity value sequence ; Cluster analysis was performed on all particle trajectories, and trajectories with a spatial distance less than 0.05m were classified as the same seepage channel;

[0031] The seepage channels are classified according to the following characteristics: the channel starting from the bottom of the rod and along the inner side of the prestressed steel bar is classified as the first leakage channel; the channel starting from the contact surface between the rod and the cushion and along the outer side of the rod is classified as the second leakage channel; the channel starting from the contact surface between the steel casing and the raft and penetrating the raft is classified as the third leakage channel; the channel starting from the contact surface between the flexible waterproof layer and the prestressed steel bar is classified as the fourth leakage channel;

[0032] The Computational Fluid Dynamics (CFD) module is a specialized fluid simulation engine integrated into BIM software. It numerically solves the governing equations for fluid motion and simulates groundwater seepage behavior in anti-floating anchor waterproofing systems. The Darcy-Brinkman equation is an extended governing equation for fluid motion in porous media. It combines Darcy's law (for low-velocity seepage) with the Navier-Stokes equation (accounting for viscous effects), making it particularly well-suited for simulating complex seepage problems in anchor waterproofing systems. Particle tracking is a post-processing technique that releases virtual tracer particles in a calculated velocity field and tracks their motion, thereby visualizing the actual groundwater flow path.

[0033] Furthermore, according to the set groundwater pressure parameters, the corresponding working pressure is applied at the inlet boundary conditions, including: Under normal working conditions, a pressure of 0.3MPa to 0.5MPa is applied at the main inlet , apply pressure at the secondary inlet 80%; Under extreme working conditions, apply a pressure of 0.8MPa to 1.0MPa at the main inlet , apply pressure at the secondary inlet 80%;

[0034] Furthermore, traditional anti-floating anchor seepage analysis assumes uniform permeability, meaning that a single average permeability coefficient is used for CFD simulations of the entire waterproofing system. This simplification has a fundamental flaw: it fails to identify the "short-circuiting effect" of localized high-permeability channels. In actual projects, groundwater automatically seeks the path of least resistance. Even if the high-permeability area accounts for only 5% of the total volume, it may carry more than 80% of the seepage volume. The homogenized model calculates an "idealized" uniform seepage field, which is far from the actual "finger-like" or "channel-like" seepage pattern, resulting in a lack of targeted waterproofing design.

[0035] Therefore, in this application, by constructing a continuously changing spatial permeability distribution function Simulate heterogeneous flow fields. Specifically, the computational fluid dynamics (CFD) module is used to solve the groundwater velocity and pressure field distribution based on the Darcy-Brinkman equation, including:

[0036] The local permeability coefficient of each sub-region Convert to permeability parameters and construct a heterogeneous seepage field: For each sub-region i, calculate the permeability: ; Establish spatial permeability distribution function , the sub-regions Assign values ​​to the corresponding spatial positions; where g is the acceleration due to gravity (9.81 m / s²), ρ is the density of water (1000 kg / m³), and μ is the dynamic viscosity of water (0.001 Pa·s);

[0037] Construct the governing equations for seepage in heterogeneous porous media in the CFD module: momentum equation (Darcy-Brinkman equation): ; Continuity equation: ; where u is the velocity vector, p is the pressure, and ε is the porosity (taken as 0.3-0.5). is the spatially varying permeability; in particular, It reflects the spatial variation of the permeability resistance. In the high permeability area (large K value), the resistance term is small and the flow rate is large; in the low permeability area (small K value), the resistance term is large and the flow rate is small. The spatial changes in the flow automatically guide the fluid to form a dominant seepage path.

[0038] Set boundary conditions and numerical solution parameters: Main entrance ( ): Apply pressure to the boundary ; Secondary entrance (only ): Apply pressure to the boundary ; Anchor head outlet: apply zero pressure boundary p=0; use finite volume method for discretization and SIMPLE algorithm for solution; Convergence criterion: residual error is less than ;

[0039] Perform iterative solution to obtain the heterogeneous seepage field distribution: velocity field : reflects the difference in flow velocity in different permeability areas; pressure field : Display the pressure distribution in heterogeneous media; extract the seepage volume of each sub-area , used to identify the main seepage paths.

[0040] Another aspect of the present application also provides a BIM-based anti-floating anchor construction system, including: a node design module, which obtains the initial waterproof node design scheme of the prestressed anti-floating anchor, and the waterproof nodes include the tensioning part waterproof node and the anchor head waterproof node; a BIM modeling module, which establishes a BIM model of the prestressed anti-floating anchor according to the initial waterproof node design scheme; a seepage simulation module, which uses the BIM model to simulate the seepage of the prestressed anti-floating anchor under different groundwater pressure conditions and identifies potential leakage channels; a blocking treatment module, which adopts different blocking measures to treat the identified potential leakage channels according to the simulation results; a parameter update module, which sets corresponding blocking measures in the BIM model to obtain a BIM model containing blocking measures; a drawing generation module, which uses the BIM model containing blocking measures to generate waterproof node construction drawings to guide on-site construction.

[0041] Compared with the existing technology, the advantages of this application are:

[0042] In view of the difficulty in accurately identifying various potential leakage channels under different groundwater pressure conditions during the construction of prestressed anti-floating anchor rods, the existing technology generally adopts a unified waterproof design based on experience and specifications, and sets the same waterproof measures at all possible seepage locations. However, there are three fundamental defects: First, it is unable to identify the real high-risk seepage channels, resulting in insufficient waterproofing of key locations; second, it ignores the spatial variability of the construction quality of the connection interface and simplifies the non-homogeneous interface into a homogeneous treatment; third, it lacks the ability to dynamically analyze the changes in the seepage path under different pressure conditions. This application establishes a BIM model that integrates CFD fluid dynamics analysis, introduces the construction gap distribution density coefficient α, the grouting density coefficient β and the interface roughness coefficient γ to modify Darcy's law, and adopts a weight distribution mechanism based on the seepage contribution ( ), achieved accurate simulation of the heterogeneous seepage field in the prestressed anti-floating anchor system, thereby accurately identifying four typical leakage channels under normal working conditions (0.3-0.5MPa) and extreme working conditions (0.8-1.0MPa), and formulated targeted differentiated plugging strategies based on the seepage mechanism characteristics of each channel, thereby improving the reliability of the prestressed anti-floating anchor waterproofing. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present application will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, the same numbers represent the same structures, wherein:

[0044] Figure 1 is a schematic diagram of an exemplary application scenario of a BIM-based anti-floating anchor construction method according to some embodiments of the present application;

[0045] Figure 2This is a BIM three-dimensional model diagram of a prestressed anchor node according to some embodiments of the present application. DETAILED DESCRIPTION

[0046] The method and system provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0047] This example uses a large commercial complex project as an example to illustrate the specific implementation process of a BIM-based anti-floating anchor construction method. The project has a total construction land area of ​​4,197.85 square meters and a planned total building area of ​​93,516.47 square meters, including approximately 58,632.86 square meters of above-ground floor area and approximately 34,883.61 square meters of underground floor area. The building structure consists of a frame shear wall system with four underground floors and 21 above-ground floors.

[0048] The project uses pressure-bearing, expanded-body anchors as permanent anti-floating components with a design life of 50 years. A total of 1,076 expanded-head anti-floating anchors were deployed. Anchor layout parameters include: 2.0m spacing (1.8m in some locations), effective length of 11.0m, standard anchor section with a 200mm diameter and 6.0m length, and spray-expanded section with a 600mm diameter and 5.0m length. PSB1080 grade prestressed concrete threaded steel bars were used as prestressed reinforcement.

[0049] The project site is located in a complex environment. The building elevation of ±0.000 is equivalent to an absolute elevation of 93.00m, the anti-floating water level is an absolute elevation of 86.00m, and the underground garage foundation is buried at a depth of -18.80m, with a base elevation of 74.20m. The project's south side abuts Long Lake, with a lake surface elevation of approximately 83.50m and a designed normal water level of 85.50m. The site is classified as a Class II environmental type, and groundwater exhibits mild corrosion to reinforced concrete structures under alternating dry and wet conditions. Due to the abundant groundwater, prestressed anti-floating anchors must penetrate the foundation raft slab. Existing waterproofing measures are insufficient to ensure waterproofing quality, necessitating effective measures to ensure the waterproofing performance of the anti-floating anchors.

[0050] like Figure 1 As shown in the figure, the initial waterproof node design scheme of the prestressed anti-floating anchor rod is obtained, and the waterproof nodes include the waterproof nodes of the tensioning part and the waterproof nodes of the anchor head. According to the initial waterproof node design scheme, the BIM model of the prestressed anti-floating anchor rod is established. The BIM model is used to simulate the seepage of the prestressed anti-floating anchor rod under different groundwater pressure conditions to identify potential leakage channels.

[0051] Based on the simulation results, different plugging treatments were applied to the identified potential leakage channels. These included: the first leakage channel, where groundwater passes through the bottom of the rod along the inner side of the prestressed steel bars to the anchor head, was plugged with an expansion waterstop strip; the second leakage channel, where groundwater passes through the rod and cushion along the outer side of the rod to the anchor head, was plugged with non-solidifying asphalt; the third leakage channel, where groundwater passes through the raft slab and penetrates the raft slab to reach the anchor head, was plugged by welding a waterstop ring on the outer side of the steel casing; and the fourth leakage channel, where groundwater passes through the junction of the flexible waterproof layer and the prestressed steel bars along the prestressed steel bars to reach the anchor head, was plugged with non-solidifying asphalt.

[0052] Corresponding blocking measures are set in the BIM model to obtain a BIM model including blocking measures; the BIM model including blocking measures is used to generate waterproof node construction drawings to guide on-site construction.

[0053] Specifically, during the initial implementation phase of S1, comprehensive data collection was conducted on the project's waterproofing node design. Initial design data for the prestressed anti-floating anchor bolts was obtained through design document analysis, on-site inspections, and expert consultation. This data collection included: structural parameters for the waterproofing nodes in the tensioning area, including anchor pad dimensions, anchor model, and tensioning stress; structural parameters for the anchor head waterproofing nodes, including anchor head protective layer thickness and sealing material type; data on the connection between the anchor bolt and the surrounding structure, including the contact area and contact pattern between the bolt body and the bedrock, cushion layer, and raft; and performance parameters for the waterproofing material, including flexible waterproofing layer thickness and material permeability coefficient.

[0054] Analysis of the collected data revealed the following issues with the original design's common construction nodes: The anti-floating anchor rods failed to effectively block water flow, lacking waterproofing measures at locations where the anchor rods penetrated the cushion and raft slabs; groundwater could penetrate the waterproof layer through weak junctions between the flexible waterproof layer and the prestressed steel bars; and the waterproof layer's construction quality control points were unclear, making it prone to leaks. Based on these analysis results, two key areas for optimizing waterproofing nodes were identified: a waterproofing node solution tensioned on the raft slab was adopted for tensioning locations; and a sealed anchor head waterproofing node solution using welded steel plates.

[0055] S2, to establish an accurate BIM model, first carried out detailed data preparation work: geometric data processing: the coordinate position data of 1076 anchor rods were imported into the BIM platform, and each anchor rod contained X, Y, and Z three-dimensional coordinate information; anchor rod geometric parameter standardization: the ordinary section has a diameter of 200mm and a length of 6000mm; the expanded section has a diameter of 600mm and a length of 5000mm; raft slab thickness data: the thickness varies between 800 and 1200mm depending on the area; cushion layer thickness data: the standard thickness is 100mm.

[0056] Material attribute data: Concrete strength grade: C35 (raft slab), C30 (cushion), C25 (anchor grouting); steel bar material parameters: PSB1080 grade, yield strength 1080 MPa; waterproofing material parameters: flexible waterproofing membrane thickness 4 mm, permeability coefficient ≤ 1×10⁻¹²cm / s.

[0057] Parametric modeling was employed, enabling batch modeling through the compilation of modeling rules. Parametric anchor modeling: Anchor family files were defined, with variable parameters set, including anchor length L, standard section diameter D1, expanded section diameter D2, and inclination angle α. 1076 anchor instances were generated through parameter-driven methods, each inheriting the geometric rules of the family file. Each anchor was assigned a unique number, establishing a correspondence with the construction drawings. Detailed waterproofing node modeling: Tensioning node: A detailed model was created, including the steel casing (89mm outer diameter, 4.5mm wall thickness), cover plate (10mm thickness), and anchor pad (200×200×20mm). Anchor head node: A 3D model of the 4mm-thick steel plate protective sleeve was created, ensuring accurate representation of the weld relationship with the anchor pad. The waterstop structure: A detailed model of the waterstop wing ring (50×3mm, 250mm spacing) and expansion waterstop strip (20×30mm cross-section) was created.

[0058] S3. Based on the actual project conditions and regulatory requirements, groundwater pressure parameters for two operating conditions were set in the BIM model: Normal operating pressure setting: Considering a groundwater level of 85.50 m (normal storage level) and a base elevation of 74.20 m; the calculated hydrostatic pressure is: P1 = ρgh = 1000 × 9.81 × (85.50 - 74.20) = 0.11 MPa. Considering dynamic water pressure and a safety factor, the normal operating pressure range is set to 0.3-0.5 MPa; 0.4 MPa is used as the representative value for normal operating conditions in the simulation. Extreme operating pressure setting: Considering a 100-year flood level and a sharp rise in groundwater levels, the extreme operating pressure range is set to 0.8-1.0 MPa; 0.9 MPa is used as the representative value for the extreme operating condition in the simulation.

[0059] Accurately establishing the connection surfaces between components in the BIM model is the key to identifying potential water seepage paths: Connection surface definition and meshing:

[0060] Contact surface between the rod and the bedrock: the surface area of ​​the expanded section = π × 0.6 × 5.0 = 9.42 m²; divided into 942 sub-areas of 0.01 m²; each sub-area is assigned independent material property parameters.

[0061] Contact surface between the rod and the cushion: the portion of the ordinary section passing through the cushion = π × 0.2 × 0.1 = 0.063 m²; discretized into 63 sub-areas, taking into account the uneven distribution of construction gaps.

[0062] Contact surface between prestressed steel bars and grouting body: Steel bar surface area = π × 0.032 × 11.0 = 1.106 m²; divided into 1106 sub-areas, focusing on the density of the steel bar threads.

[0063] The contact surface between the flexible waterproof layer and the prestressed steel bar: contact perimeter: π×0.032=0.1m; a monitoring point is set every 10mm along the height direction.

[0064] Contact surface between steel casing and raft: annular contact area: π×(0.089²-0.080²)×0.8=0.021m²; finely divided into 210 sub-areas.

[0065] Set local material property parameters for each sub-area based on construction quality statistics and engineering experience:

[0066] Construction joint distribution density coefficient α: High-quality construction area: α = 0.1-0.3; General construction area: α = 0.4-0.6; Difficult construction area: α = 0.7-1.0. A random distribution function is used to assign values ​​to each sub-area to simulate the unevenness of actual construction.

[0067] Grouting density coefficient β: expansion section (high-pressure grouting): β = 0.9-1.0; ordinary section (normal pressure grouting): β = 0.8-0.9; near the contact surface: β = 0.7-0.8; normal distribution is used to simulate the spatial variation of density.

[0068] Interface roughness coefficient γ: concrete-concrete interface: γ = 2.0-3.0; concrete-rock interface: γ = 1.5-2.5; steel-concrete interface: γ = 1.0-1.5; automatically assigned according to the material combination type.

[0069] The local permeability coefficient of each sub-area is calculated using the modified Darcy's law and the equivalent permeability coefficient of the connection interface : Determination of foundation permeability coefficient: Complete concrete: ; Concrete containing defects: ; Corrected calculation: ,in, For a sub-region of the contact surface between the rod and the bedrock: α = 0.5, β = 0.85, γ = 2.0; .

[0070] Calculation of equivalent permeability coefficient: The weighted average method is used to calculate the equivalent permeability coefficient of the entire connection interface: The calculation results show that the contact surface between the rod and the bedrock is: ;Contact surface between rod and cushion: ;Contact surface between steel casing and raft: (exceeds the threshold).

[0071] The CFD calculation module is integrated into the BIM platform, and the finite volume method is used for discretization. A cylindrical area with a radius of 2m and a single anchor rod as the center is used. A structured grid is used, and local encryption is performed near the contact surface. The total number of grids is about 500,000. Entrance boundary: Main entrance ( Greater than ): Apply pressure 0.4MPa (normal working condition); Secondary inlet ( Greater than ): Apply a pressure of 0.32 MPa. Outlet boundary: The anchor head position is set as a free outflow boundary with a pressure of 0. The anchor surface and surrounding soil are set as no-slip walls.

[0072] The SIMPLE algorithm is used to solve the pressure-velocity coupling, with a time step of 0.01s at the initial stage and adaptive adjustment based on the convergence situation. The convergence criterion is that the residuals of all variables are less than Total calculation time: 12 hours of simulation of the seepage process. The following data are output at each time step: Velocity field distribution: ; Pressure field distribution: ; Streamline distribution and flow changes at each monitoring point.

[0073] 2000 tracer particles were released at the primary seepage interface and 1000 tracer particles were released at the secondary seepage interface. The particles had an initial velocity of 0 and moved with the flow field. The particle motion equations were solved using the fourth-order Runge-Kutta method with a time step of 0.001 s. The following data was recorded for each particle: Position coordinate sequence: ; Speed ​​sequence: , material area number passed, total movement time.

[0074] Through cluster analysis of 10,000 particle trajectories, four main types of leakage channels were identified:

[0075] The first leakage channel (accounting for 15% of the total flow): starting point: the expanded section at the bottom of the rod body, path: upward along the interface between the prestressed steel bar and the grouting body, end point: inside the anchor head, average seepage time: 4.5 hours.

[0076] The second leakage channel (accounting for 25% of the total flow): starting point: the contact surface between the rod and the cushion layer, path: upward along the outer surface of the rod; end point: outside the anchor head; average seepage time: 3.2 hours.

[0077] The third leakage channel (accounting for 40% of the total flow): starting point: the annular gap where the steel casing contacts the raft slab; path: penetrating the thickness of the raft slab; end point: the bottom of the anchor head; average seepage time: 1.8 hours.

[0078] The fourth leakage channel (accounting for 20% of the total flow): starting point: edge of the flexible waterproof layer; path: along the surface of the prestressed steel bar; end point: top of the anchor head; average seepage time: 2.5 hours.

[0079] Based on the four types of leakage channels identified through simulation, a targeted blocking plan was developed:

[0080] To seal the first leak, a water-expanding waterstop strip with a size of 20 x 30 mm and an expansion rate of 300% or higher was used. Installation location: Inside the PVC sleeve at the base of the anchor rod, 50 mm from the bottom. Number of installations: Two strips per anchor rod, spaced 100 mm apart. Pre-compression ratio: 30% to ensure an initial seal. Quality control criteria: A water injection test within 24 hours of installation, ensuring no leakage. Simulation tests on three sets of specimens collected the following data: Initial state: Gap width 2-3 mm; After 24 hours of exposure to water: The waterstop strip completely fills the gap; Pressure bearing capacity: No leakage for 72 hours at 0.6 MPa.

[0081] The second leak channel was sealed using a self-healing, non-curing rubberized asphalt waterproof coating. Sealing process data: Coating range: 100mm below the cushion layer to 100mm above the cushion layer; Coating thickness: 3mm (applied in two applications); Material usage: 1.5kg / m²; Curing time: Surface dry in 2 hours, full dry in 24 hours. Construction process monitoring data: Ambient temperature: 15-25°C; Relative humidity: ≤80%; Coating thickness testing: 9 points per 10m²; Continuity testing: Spark testing was used to confirm no leaks.

[0082] Third, to seal the leaking channel, water-stop wing ring design data: Wing ring specifications: 50mm width, 3mm thickness; quantity: 2 per steel casing; spacing: 250mm; welding requirements: full weld, weld height ≥ 3mm. Welding quality control data: preheat temperature before welding: 150°C; welding current: 120-140A; welding speed: 150-200mm / min; weld flaw detection: 100% ultrasonic testing, 100% pass rate.

[0083] The fourth leakage channel is sealed, and the treatment scope is: the overlapping part of the flexible waterproof layer; the additional layer is set: width 300mm; overlapping length: ≥100mm; bonding strength: ≥0.7MPa.

[0084] Accurately model the determined blocking measures in the BIM model:

[0085] Model updates include: Waterstop model: Create a parametric waterstop family, including morphological changes before and after expansion; Paint layer model: Generate a 3mm thick paint layer through the surface offset function; Waterstop wing ring model: Accurately model the weld morphology for engineering quantity statistics; Waterproof additional layer: Establish a model for the overlap relationship of multiple layers of waterproof membranes.

[0086] Re-run the CFD simulation on the BIM model including the containment measures:

[0087] Simulation results data: First leaking channel: flow reduced by 99.8%, basically blocked; second leaking channel: flow reduced by 99.5%, effectively blocked; third leaking channel: flow reduced by 99.9%, completely blocked; fourth leaking channel: flow reduced by 99.6%, effectively controlled.

[0088] Comprehensive waterproofing effect evaluation: Normal working conditions (0.4MPa): water seepage <0.1L / d·root; extreme working conditions (0.9MPa): water seepage <0.5L / d·root; waterproofing level that meets the requirements of the specifications.

[0089] Based on the optimized BIM model, such as Figure 2 As shown, construction drawings were automatically generated. During the construction of the 1,076 anti-floating anchors, a comprehensive data monitoring system was established. Quality inspection data summary: Waterstop wing ring weld inspection: 1,076 x 2 = 2,152 inspections, 100% pass rate; Paint thickness inspection: 200 random inspections, average thickness 3.2 mm, standard deviation 0.15 mm; Waterproofing membrane overlap: 500 random inspections, overlap length ≥ 100 mm. Field test data: Water injection test: All 1,076 anchors were maintained at a pressure of 0.5 MPa for 24 hours; Test results: No leakage, 100% success rate; Long-term monitoring: Retest after 6 months of operation, still maintained 100% waterproofing.

[0090] The invention of the present application and its implementation methods are described schematically above. This description is not restrictive. Without departing from the spirit or basic features of the present application, the present application can be implemented in other specific forms. What is shown in the accompanying drawings is only one of the implementation methods of the invention of the present application, and the actual structure is not limited to this. Therefore, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the invention, a structural method and embodiment similar to the technical solution are designed without creativity, which should all fall within the scope of protection of the present application. In addition, the word "including" does not exclude other elements or steps, and the word "one" before an element does not exclude the inclusion of "multiple" elements. Words such as first and second are used to indicate names and do not indicate any specific order.

Claims

1. A BIM-based anti-floating anchor construction method, characterized in that: include: S1, obtain the initial waterproof node design scheme of the prestressed anti-floating anchor rod, the waterproof nodes include the tensioning part waterproof nodes and the anchor head waterproof nodes; S2: Based on the initial waterproof node design, a BIM model of the prestressed anti-floating anchor was established; S3, using the BIM model to simulate the water seepage of prestressed anti-floating anchors under different groundwater pressure conditions and identify potential leakage channels; S4, based on the simulation results, performs different blocking treatments on the identified potential leakage channels, including: The first leakage channel where groundwater passes through the bottom of the rod along the inner side of the prestressed steel bar and reaches the anchor head is blocked with an expansion water stop strip; The second leakage channel where groundwater passes through the rod and cushion along the outside of the rod to the anchor head is blocked with non-solidified asphalt; The third leakage channel where groundwater penetrates the raft through the rod inside the raft and reaches the anchor head is blocked by welding a water stop ring on the outside of the steel casing; For the fourth leakage channel where groundwater passes through the junction of the flexible waterproof layer and the prestressed steel bars and reaches the anchor head along the prestressed steel bars, non-solidified asphalt is used for blocking; S5, setting corresponding blocking measures in the BIM model to obtain a BIM model including the blocking measures; S6, use the BIM model including sealing measures to generate waterproof node construction drawings to guide on-site construction.

2. The BIM-based anti-floating anchor construction method according to claim 1, characterized in that: The waterproof nodes of the tensioning parts are treated with the waterproof nodes tensioned on the raft slabs; The anchor head waterproof node is sealed by steel plate welding.

3. The BIM-based anti-floating anchor construction method according to claim 1, characterized in that: S3, using the BIM model to simulate the seepage of prestressed anti-floating anchors under different groundwater pressure conditions and identify potential leakage channels, including: Set groundwater pressure parameters in the BIM model. Groundwater pressure parameters include normal working pressure and extreme working pressure; Establish the connection surfaces between the various components of the prestressed anti-floating anchor in the BIM model. The connection surfaces include: the contact surface between the rod body and the bedrock, the contact surface between the rod body and the cushion layer, the contact surface between the prestressed steel bar and the grouting body, the contact surface between the flexible waterproof layer and the prestressed steel bar, and the contact surface between the steel casing and the raft slab. Under the influence of groundwater pressure parameters, the permeability coefficient of groundwater passing through each connection surface is calculated through the BIM model. When the permeability coefficient is greater than the preset threshold, the corresponding connection surface is determined to be a potential seepage interface; Based on the potential seepage interface, simulate the groundwater seepage path through the BIM model; According to the starting position and flow direction of the seepage path, the potential leakage channels are divided into the first to fourth leakage channels.

4. The BIM-based anti-floating anchor construction method according to claim 3, characterized in that: Normal operating pressure is 0.3MPa to 0.5MPa; The ultimate working pressure is 0.8MPa to 1MPa.

5. The BIM-based anti-floating anchor construction method according to claim 3, characterized in that: Under the influence of groundwater pressure parameters, the BIM model is used to calculate the permeability coefficient of groundwater passing through each connection surface. When the permeability coefficient is greater than the preset threshold, the corresponding connection surface is determined to be a potential seepage interface, including: Discretize each connection surface into multiple sub-areas in the BIM model; For each sub-area, the corresponding local material attribute parameters are set respectively. The local material attribute parameters include: construction gap distribution density coefficient α; grouting density coefficient β; interface roughness coefficient γ; The local permeability coefficient of each sub-area is calculated using the modified Darcy's law and the equivalent permeability coefficient of the corresponding connection interface ; When the local permeability Greater than , or equivalent permeability coefficient Greater than When , the corresponding connection interface is determined to be a potential water seepage interface.

6. The BIM-based anti-floating anchor construction method according to claim 5, characterized in that: The local permeability coefficient of each sub-area is calculated using the modified Darcy's law and the equivalent permeability coefficient of the corresponding connection interface ,include: ,in, is the area of ​​the ith subregion, is the weight coefficient, , is the maximum permeability coefficient of all sub-areas; , where Q is the seepage rate per unit time, L is the length of the seepage path, and ΔP is the pressure difference.

7. The BIM-based anti-floating anchor construction method according to claim 5, characterized in that: Based on the potential seepage interface, the BIM model is used to simulate the groundwater seepage path, including: Integrate computational fluid dynamics (CFD) modules into BIM models; Set the groundwater inlet boundary condition: Set the local permeability coefficient Greater than The area is set as the main inlet, and the equivalent permeability coefficient Greater than Set the secondary entrance in the area and set the anchor head position to the exit boundary; According to the set groundwater pressure parameters, the corresponding working pressure is applied at the inlet boundary condition; Computational fluid dynamics (CFD) module is used to solve the groundwater velocity and pressure field distribution based on the Darcy-Brinkman equation. According to the distribution of velocity field and pressure field, streamline tracing is performed by particle tracing method to obtain the seepage path of groundwater from each potential seepage surface to the anchor head. According to the starting position and flow direction of the seepage path, the potential leakage channels are divided into the first to fourth leakage channels.

8. The BIM-based anti-floating anchor construction method according to claim 7, characterized in that: According to the set groundwater pressure parameters, the corresponding working pressure is applied at the inlet boundary conditions, including: Under normal working conditions, a pressure of 0.3MPa to 0.5MPa is applied at the main inlet. , apply pressure at the secondary inlet 80%; Under extreme working conditions, a pressure of 0.8MPa to 1.0MPa is applied at the main inlet. , apply pressure at the secondary inlet 80% of.

9. The BIM-based anti-floating anchor construction method according to claim 7, characterized in that: The computational fluid dynamics (CFD) module is used to solve the groundwater velocity and pressure field distribution based on the Darcy-Brinkman equation, including: The local permeability coefficient Ki is converted into the corresponding permeability parameter, and the heterogeneous seepage field is established according to the permeability parameter; The computational fluid dynamics (CFD) module is used to solve the heterogeneous seepage field based on the Darcy-Brinkman equation to obtain the velocity field and pressure field distribution of groundwater.

10. A BIM-based anti-floating anchor construction system, characterized in that: include: The node design module obtains the initial waterproof node design scheme of the prestressed anti-floating anchor rod. The waterproof nodes include the waterproof nodes at the tensioning part and the waterproof nodes at the anchor head. BIM modeling module, based on the initial waterproof node design plan, establishes the BIM model of the prestressed anti-floating anchor rod; The water seepage simulation module uses the BIM model to simulate the water seepage of prestressed anti-floating anchors under different groundwater pressure conditions and identify potential leakage channels; The plugging treatment module adopts different plugging measures to treat the identified potential leakage channels according to the simulation results; A parameter updating module sets corresponding blocking measures in the BIM model to obtain a BIM model including the blocking measures; The drawing generation module uses the BIM model including sealing measures to generate waterproof node construction drawings to guide on-site construction.

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