BIM-based anti-floating anchor rod construction method and system

Abstract

The application discloses a BIM-based anti-floating anchor rod construction method and system, and relates to building construction: an initial waterproof joint design scheme of a prestressed anti-floating anchor rod is acquired, and a BIM model of the prestressed anti-floating anchor rod is established; the BIM model is used to simulate water seepage conditions of the prestressed anti-floating anchor rod under different groundwater pressure conditions, and potential water leakage channels are identified; different plugging treatments are carried out on the identified potential water leakage channels, including: for a first water leakage channel, an expansion waterstop is used for plugging; for a second water leakage channel, non-solidified asphalt is used for plugging; for a third water leakage channel, a waterstop wing ring is welded on the outside of a steel casing pipe for plugging; for a fourth water leakage channel, non-solidified asphalt is used for plugging; corresponding plugging measures are set in the BIM model, and a BIM model containing the plugging measures is obtained; a waterproof joint construction drawing is generated by using the BIM model containing the plugging measures, and field construction is guided. The application effectively reduces the leakage risk of underground engineering.

Description

TECHNICAL FIELD

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

[0002] The waterproof system of prestressed anti-floating anchor rods has unique complexity. Unlike ordinary waterproof engineering, anti-floating anchor rods need to penetrate the entire underground structure, forming a continuous channel from the bedrock to the top of the raft. This feature leads to four aspects of waterproofing problems:

[0003] First, the diversity and concealment of the water seepage path. Groundwater can seep through multiple paths: along the inside of the prestressed reinforcement, along the outside of the rod body, through the raft, through the flexible waterproof layer, etc. These paths are intertwined, and under different groundwater pressure conditions, the dominant seepage path may change, making it difficult for traditional single waterproof measures to fully respond.

[0004] Second, the heterogeneity of the connection interface. Anti-floating anchor rods involve multiple material interfaces: rod body and bedrock, rod body and cushion, prestressed reinforcement and grouting body, flexible waterproof layer and prestressed reinforcement, steel casing and raft, etc. The permeation characteristics of each interface differ greatly, and there are non-homogeneous features such as irregular distribution of construction gaps, local differences in grouting density, and spatial variations in interface roughness. Traditional homogeneous seepage theory cannot accurately describe this complex seepage behavior.

[0005] Third, the dynamic changes in groundwater pressure. Groundwater pressure changes dynamically with factors such as season, rainfall, and groundwater level. Under normal conditions, it can be 0.3-0.5 MPa, and under extreme conditions, it can reach 0.8-1.0 MPa. Under different pressure conditions, the dominant mechanism and path of seepage can be completely different, requiring detailed analysis under different working conditions.

[0006] Fourth, the lack of targeted waterproof measures. Existing technologies usually use uniform waterproof standards and measures, failing to take differentiated plugging strategies based on the characteristics of different leakage channels. For example, for fine gap seepage along the inside of the prestressed reinforcement, expansion joint sealant is needed; while for surface seepage on the outside of the rod body, flexible materials such as non-solidified asphalt are needed.

[0007] Existing design methods mainly rely on two-dimensional drawings and simplified calculations, which cannot accurately simulate the complex seepage process in three-dimensional space. Construction personnel have difficulty in intuitively understanding various potential leakage paths, let alone predicting seepage risks under different working conditions. This leads to a disconnect between waterproof design and actual needs, resulting in either insufficient waterproofing leading to leakage or excessive waterproofing causing waste.

[0008] Therefore, there is an urgent need for a technical method that can accurately identify various potential water leakage channels under different groundwater pressure conditions, enabling precise design and construction guidance for the prestressed anti-floating anchor rod waterproof system. SUMMARY

[0009] In view of the difficulty in accurately identifying various potential water leakage channels under different groundwater pressure conditions during the construction of the prestressed anti-floating anchor rod, the present 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 waterproof system, identifies four typical water leakage channels and takes corresponding targeted plugging measures, effectively reducing the leakage risk of underground engineering.

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

[0011] S4, according to the simulation results, different plugging treatments are carried out on the identified potential water leakage channels, including: for the first water leakage channel in which groundwater passes through the bottom of the rod body along the inside of the prestressed reinforcement to reach the anchor head, an expansion waterstop is used for plugging; for the second water leakage channel in which groundwater passes through the rod body and the cushion along the outside of the rod body to reach the anchor head, non-solidified asphalt is used for plugging; for the third water leakage channel in which groundwater penetrates the raft plate through the inner rod body to reach the anchor head, a water stop wing ring is welded outside the steel casing for plugging; for the fourth water leakage channel in which groundwater reaches the anchor head along the prestressed reinforcement at the junction of the flexible waterproof layer and the prestressed reinforcement, non-solidified asphalt is used for plugging;

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

[0013] The first water leakage channel reflects the entry of groundwater from the bottom of the anchor rod body (the bedrock anchoring segment), the upward penetration along the tiny gap between the prestressed reinforcement and the grouting body, and finally the arrival at the anchor head position at the top of the raft. During the construction of the anchor rod, it is difficult to achieve complete compaction of the combination between the surface of the prestressed reinforcement and the grouting body, especially in the case of rust, oil stains on the surface of the reinforcement, or insufficient grouting and vibration, which will form a continuous capillary channel. Although this channel is extremely tiny (usually less than 0.1mm), it can still form a stable seepage path under the action of groundwater pressure.

[0014] The second water leakage channel reflects that the underground water enters from the contact surface between the anchor rod body and the surrounding soil (or bedrock), penetrates upward along the outer surface of the rod body, passes through the contact interface between the cushion and the rod body, continues to rise along the outside of the rod body, and finally bypasses the waterproof structure to reach the anchor head position. When grouting is performed after the anchor rod is formed, irregularities such as hole collapse and overbreak may exist in the hole wall, resulting in gaps between the grouting body and the hole wall; at the same time, shrinkage of the grouting body during the solidification process also forms annular gaps on the outside of the rod body. These gaps may be further enlarged at the cushion position due to improper construction joint treatment.

[0015] The third water leakage channel reflects that the underground water penetrates through the entire raft slab thickness along the contact surface between the anchor rod body and the raft slab concrete, or through the construction gap between the steel casing and the raft slab, forms a vertical upward water penetration channel inside the raft slab, and finally seeps out on the surface of the raft slab near the anchor head. A steel casing needs to be pre-buried when the anchor rod passes through the raft slab, and the bonding surface between the steel casing and the raft slab concrete is a natural weak link. If the surface of the steel casing is not properly treated, the concrete is not vibrated densely during pouring, or the steel casing produces a slight displacement during the hardening process of the concrete, a through gap will be formed at the interface.

[0016] The fourth water leakage channel reflects that the underground water first reaches the position of the flexible waterproof layer at the bottom of the raft slab, then enters from the combination site of the flexible waterproof layer and the prestressed steel bar (i.e. the node where the waterproof layer is penetrated by the steel bar), penetrates upward along the gap between the surface of the steel bar and the waterproof layer, and finally reaches the anchor head. The flexible waterproof layer (such as waterproof roll material, paint, etc.) needs special treatment at the position where the prestressed steel bar passes through, but due to the large difference in material between the steel bar and the flexible material, the different thermal expansion and contraction coefficients, and the improper sealing treatment during construction, it is easy to form a water seepage weak point at the combination site. Especially during the slight movement of the steel bar during tensioning, the sealing property of the site is further damaged.

[0017] Further, the waterproof node at the tensioning site is treated by tensioning on the raft slab, and the waterproof node at the anchor head is treated by welding a steel plate to seal. Among them, the waterproof node at the tensioning site refers to the waterproof structure provided in the area where the prestressed anti-floating anchor rod is tensioned on the top surface of the raft slab, 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 bar penetrates out of the raft slab and is 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 point. The raft slab is poured first, then the tensioning operation is performed, and finally the waterproof sealing is performed, avoiding the difficulty of tensioning in the narrow space below the raft slab.

[0018] The anchor head waterproof joint refers to the joint between the fixed end (i.e. the bottom end anchored in the bedrock) of the prestressed anti-floating anchor rod and the grouting body and the surrounding rock, and the waterproof structure provided in this region to block the upward flow of groundwater along the anchor rod. Located at the bottom of the anchor rod, the end of the anchoring section deep into the bedrock serves as the first line of defense against groundwater infiltration into the anchor rod system and prevents groundwater from entering and permeating upward along the anchor rod.

[0019] Further, S3, simulating the water infiltration of the prestressed anti-floating anchor rod under different groundwater pressure conditions by using the BIM model, identifying potential water leakage channels, including: setting the groundwater pressure parameters in the BIM model, the groundwater pressure parameters including the normal working condition pressure and the limit working condition pressure; establishing the connecting surfaces between the components of the prestressed anti-floating anchor rod in the BIM model, the connecting surfaces including: the rod body and the bedrock contact surface, the rod body and the cushion contact surface, the prestressed steel and the grouting body contact surface, the flexible waterproof layer and the prestressed steel contact surface, and the steel sleeve and the raft contact surface; under the action of the groundwater pressure parameters, calculating the permeability coefficients of the groundwater through each connecting surface by the BIM model, when the permeability coefficient is greater than the preset threshold value, determining that the corresponding connecting surface is a potential water infiltration interface; simulating the seepage path of the groundwater according to the potential water infiltration interface by the BIM model; according to the starting position and the flow direction of the seepage path, dividing the potential water leakage channel into the first to fourth water leakage channels.

[0020] Further, the normal working condition pressure is 0.3MPa to 0.5MPa; the limit working condition pressure is 0.8MPa to 1MPa.

[0021] Further, under the action of the groundwater pressure parameters, the BIM model is used to calculate the permeability coefficients of the groundwater through each connecting surface, and when the permeability coefficient is greater than the preset threshold value, the corresponding connecting surface is determined as a potential water infiltration interface, including: according to the geometric shape and size of the connecting interface, using an adaptive mesh division algorithm to divide the interface into n x m rectangular sub-regions; for each sub-region, set the corresponding local material property parameters, including: the construction gap distribution density coefficient α, the value range is 0.1-1.0; the grouting density coefficient β, the value range is 0.7-1.0; the interface roughness coefficient γ, the value range is 1.0-3.0.

[0022] The modified Darcy's law is used to calculate the local permeability coefficient of each sub-region and the equivalent permeability coefficient of the corresponding connecting interface ; wherein, is the area of the i-th sub-region, is the weight coefficient, , is the maximum permeability coefficient in all sub-regions; in particular, the traditional Darcy's law uses a simple arithmetic mean or an area-weighted mean to calculate the equivalent permeability coefficient, and the traditional algorithm: This method has an "average value trap" - when 99% of the area on the connecting interface has a small permeability coefficient, and only 1% of the area has construction defects leading to high permeability, the average permeability coefficient calculated by the traditional method is still small, thus leading to the false conclusion that the interface has good waterproof performance. However, in actual engineering, it is precisely this 1% of the high-permeability area that forms a dominant seepage channel, leading to the failure of the entire waterproof system.

[0023] In actual seepage processes, groundwater will automatically find the path with the smallest resistance, and the actual seepage flow of the high-permeability area far exceeds its area ratio. Therefore, the present application enhances the contribution of the high-permeability sub-region in the calculation of the equivalent permeability coefficient by making the contribution of the high-permeability sub-region in the calculation of the equivalent permeability coefficient by become , which accurately reflects the physical nature of seepage.

[0024] wherein Q is the seepage flow 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's law is Based on the assumption of homogeneous medium, the entire connecting interface is regarded as an ideal state with uniform material properties. This is seriously inconsistent with the actual construction situation of the anti-floating anchor - factors such as uneven vibration during grouting, layered bleeding, and steel blockage during grouting can cause the permeability of different positions on the same interface to differ by 2-3 orders of magnitude. The traditional method cannot identify and quantify the spatial variability of construction quality, leading to missed judgment of high-risk areas. The present application introduces a non-homogeneous correction factor on the basis of the traditional formula, the construction gap density a: directly reflects the degree of construction defects of the sub-region, the grouting density β: quantitatively represents the local difference in grouting quality, and the interface roughness γ: considers the quality of the construction interface treatment.

[0025] When the local permeability coefficient is greater than , a "point-like" leakage hidden danger is identified, and even if the high-permeability area is small, it can be accurately captured; or when the equivalent permeability coefficient is greater than , the corresponding connecting interface is determined to be a potential seepage interface; the "planar" leakage risk is evaluated to prevent the overall leakage formed by the superposition of multiple moderate-permeability areas.

[0026] In summary, the connection interface of the prestressed anti-floating anchor rod (such as the rod body and the grouting body, the prestressed steel bar and the grouting body, etc.) is not a homogeneous porous medium, but there are irregular distribution of construction gaps, local differences in grouting density, and spatial changes in interface roughness. However, the Darcy law assumes that the medium is homogeneous, and cannot accurately reflect the actual seepage characteristics of such a heterogeneous interface. The present application: divides the interface into multiple sub-regions; calculates the permeability coefficient for each sub-region; considers the differences between different regions; and comprehensively evaluates the water seepage risk of the entire interface.

[0027] Further, according to the potential water seepage interface, the seepage path of groundwater is simulated through the BIM model, including: integrating a computational fluid dynamics (CFD) module in the BIM model; setting the groundwater inlet boundary condition: setting the area with local permeability coefficient greater than as the main inlet, setting the area with equivalent permeability coefficient greater than as the secondary inlet, and setting the anchor head position as the outlet boundary; according to the set groundwater pressure parameters, applying the corresponding working pressure at the inlet boundary condition.

[0028] Using the computational fluid dynamics (CFD) module, the velocity field and pressure field distribution of groundwater are solved based on the Darcy-Brinkman equation; according to the velocity field and pressure field distribution, streamline tracking is performed through the particle tracking method to obtain the seepage path of groundwater from each potential water seepage surface to the anchor head, including: setting the tracer particle release point on the determined potential water seepage interface, wherein: setting the main release point at the center position of the sub-region with local permeability coefficient greater than , with a spacing of 0.1m; setting the secondary release point on the connection interface with only equivalent permeability coefficient greater than , with a spacing of 0.2m;

[0029] Based on the velocity field calculated by the CFD module, the particle motion trajectory is solved using the Lagrangian method: ; ; ; wherein, 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 passing through; the corresponding time sequence ; the pressure value sequence and the velocity value sequence ; all particle trajectories are clustered, and trajectories with a spatial distance less than 0.05 m are classified as the same seepage channel;

[0031] According to the following characteristics of each seepage channel: the channel starting from the bottom of the rod and along the inside of the prestressed steel is classified as the first water leakage channel; the channel starting from the contact surface of the rod and the cushion and along the outside of the rod is classified as the second water leakage channel; the channel starting from the contact surface of the steel sleeve and the raft and penetrating the raft is classified as the third water leakage channel; the channel starting from the contact surface of the flexible waterproof layer and the prestressed steel is classified as the fourth water leakage channel;

[0032] Wherein, the CFD (Computational Fluid Dynamics) module is a professional fluid simulation calculation engine integrated in the BIM software, which is used to numerically solve the control equation of fluid motion and simulate the seepage behavior of groundwater in the anti-floating anchor rod waterproof system. The Darcy-Brinkman equation is an extended control equation for describing the motion of fluid in porous media, which combines the Darcy law (suitable for low-speed seepage) and the Navier-Stokes equation (considering viscous effect), and is particularly suitable for simulating the complex seepage problem in the anchor rod waterproof system. The particle tracking method is a post-processing technique, which releases virtual tracer particles in the calculated velocity field and tracks their motion trajectories, so as to visualize the actual flow path of groundwater.

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

[0034] Further, the traditional anti-floating anchor rod seepage analysis adopts the assumption of uniform permeability, that is, a single average permeability coefficient is used for CFD simulation throughout the waterproof system. This simplified treatment has a fundamental defect: it cannot identify the "short circuit effect" of local high-permeability channels. In actual engineering, groundwater will automatically find the path with the smallest resistance, and even if the high-permeability area accounts for only 5% of the total volume, it may carry more than 80% of the seepage flow. The homogeneous model calculates the "idealized" uniform seepage field, which is far from the actual "finger-shaped" or "channel-shaped" seepage mode, resulting in the lack of targeting of waterproof design.

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

[0036] Convert the local permeability coefficient of each sub-region to the permeability parameter to construct the heterogeneous seepage field: for each sub-region i, calculate the permeability: ; establish the spatial permeability distribution function , assign the permeability of each sub-region to the corresponding spatial position; where g is the acceleration of 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 heterogeneous porous medium seepage control equation set in the CFD module: momentum equation (Darcy-Brinkman equation): ; continuity equation: ; where u is the velocity vector, p is the pressure, ε is the porosity (0.3-0.5), is the spatially varying permeability; in particular, reflects the spatially varying permeability resistance, which is small in high permeability areas (large K value) and large in low permeability areas (small K value); The spatial variation of the flow automatically guides the fluid to form a dominant seepage path.

[0038] Set the boundary conditions and numerical solution parameters: main inlet ( ): apply pressure boundary ; secondary inlet (only ): apply pressure boundary ; anchor outlet: apply zero pressure boundary p=0; use finite volume method for discretization and SIMPLE algorithm for solution; convergence criterion: residual less than ;

[0039] Perform iterative solution to obtain the distribution of the heterogeneous seepage field: velocity field : reflects the flow rate difference in different permeability regions; pressure field : shows the distribution of pressure in the heterogeneous medium; extract the seepage flow of each sub-region for identifying the main water seepage path.

[0040] Another aspect of the present application also provides a BIM-based anti-floating anchor construction system, comprising: a node design module, obtaining an initial waterproof node design scheme of a prestressed anti-floating anchor, the waterproof node including a tensioning part waterproof node and an anchor head waterproof node; a BIM modeling module, establishing a BIM model of the prestressed anti-floating anchor according to the initial waterproof node design scheme; a water seepage simulation module, simulating the water seepage of the prestressed anti-floating anchor under different groundwater pressure conditions by using the BIM model, and identifying potential water leakage channels; a plugging treatment module, treating the identified potential water leakage channels by using different plugging measures according to the simulation results; a parameter updating module, setting corresponding plugging measures in the BIM model to obtain a BIM model containing the plugging measures; and a drawing generation module, generating waterproof node construction drawings by using the BIM model containing the plugging measures to guide on-site construction.

[0041] Compared with the prior art, the present application has the following advantages:

[0042] In view of the difficulty in accurately identifying various potential water leakage channels of the prestressed anti-floating anchor under different groundwater pressure conditions during construction, the prior art generally adopts a unified waterproof design based on experience and specifications, and the same waterproof measures are set at all possible water seepage parts, but there are three fundamental defects: first, it cannot identify the real high-risk water seepage channels, resulting in insufficient waterproofing of key parts; second, it ignores the spatial variability of the connection interface construction quality, and simplifies the inhomogeneous interface as homogeneous treatment; third, it lacks dynamic analysis capability of the seepage path change under different pressure conditions. The present application establishes a BIM model integrated with CFD fluid dynamics analysis, introduces construction gap distribution density coefficient α, grouting density coefficient β and interface roughness coefficient γ to correct Darcy's law, adopts a weight distribution mechanism based on seepage contribution degree (Darcy's law is modified by introducing construction gap distribution density coefficient α, grouting density coefficient β and interface roughness coefficient γ, and a weight distribution mechanism based on seepage contribution degree is adopted ), which realizes accurate simulation of the inhomogeneous seepage field in the prestressed anti-floating anchor system, thereby accurately identifying four types of typical water leakage channels under normal conditions (0.3-0.5 MPa) and extreme conditions (0.8-1.0 MPa), and formulating targeted and differentiated plugging strategies according to the seepage mechanism characteristics of each channel, thereby improving the reliability of the prestressed anti-floating anchor waterproofing. BRIEF DESCRIPTION OF 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 reference numbers represent the same structures, wherein:

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

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

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

[0047] The embodiments take a certain large commercial complex project as an example to illustrate the specific implementation process of the BIM-based anti-floating anchor construction method. The total construction land area of the project is 4197.85 square meters, the total planning construction area is 93516.47 square meters, of which the aboveground construction area is about 58632.86 square meters, and the underground construction area is about 34883.61 square meters. The building structure is a frame-shear wall structure system with 4 underground floors and 21 aboveground floors.

[0048] The project uses pressure type expansion anchor as permanent anti-floating component, the design reference period is 50 years, and a total of 1076 expansion head anti-floating anchors are arranged. The anchor arrangement parameters are: spacing 2.0 m (locally 1.8 m), effective length 11.0 m, ordinary anchoring segment hole diameter 200 mm, length 6.0 m, and spray expansion segment diameter 600 mm, length 5.0 m. The prestressed steel bar uses PSB1080 grade prestressed concrete threaded steel bar.

[0049] The engineering environment is complex, the building ±0.000 elevation corresponds to the absolute elevation of 93.00 m, the anti-floating flood control water level is the absolute elevation of 86.00 m, the underground garage foundation is buried at a depth of -18.80 m, and the base elevation is 74.20 m. The south side of the project is adjacent to Long Lake, the lake surface elevation is about 83.50 m, and the design water area normal water level is 85.50 m. The site environment type belongs to type II, and the groundwater has a slight corrosive effect on the reinforced concrete structure under dry-wet alternating conditions. Due to the abundance of groundwater, the prestressed anti-floating anchor needs to penetrate the foundation raft, and the existing waterproof measures are difficult to ensure the waterproof quality, so effective measures need to be taken to ensure the waterproof performance of the anti-floating anchor.

[0050] As shown in Figure 1 , an initial waterproof joint design scheme of the prestressed anti-floating anchor is obtained, the waterproof joint includes a tensioning part waterproof joint and an anchor head waterproof joint; a BIM model of the prestressed anti-floating anchor is established according to the initial waterproof joint design scheme; the BIM model is used to simulate the water seepage of the prestressed anti-floating anchor under different groundwater pressure conditions, and to identify potential water leakage channels.

[0051] According to the simulation results, different plugging treatments are carried out on the identified potential water leakage channels, including: for the first water leakage channel through which underground water reaches the anchor head along the inside of the prestressed steel bar through the bottom of the rod body, an expansion waterstop is used for plugging; for the second water leakage channel through which underground water reaches the anchor head along the outside of the rod body through the rod body and the cushion, non-solidified asphalt is used for plugging; for the third water leakage channel through which underground water reaches the anchor head by penetrating the raft through the rod body inside the raft, a water stop wing ring is welded outside the steel casing pipe for plugging; for the fourth water leakage channel through which underground water reaches the anchor head along the prestressed steel bar at the joint of the flexible waterproof layer and the prestressed steel bar, non-solidified asphalt is used for plugging;

[0052] Corresponding plugging measures are set 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 to guide the on-site construction.

[0053] Specifically, S1, in the initial stage of implementation, first, the waterproof node design scheme of the project is comprehensively data collected. Through design file analysis, site survey and expert consultation, the initial waterproof node design data of the prestressed anti-floating anchor rod are obtained. The data collection contents include: the construction parameters of the waterproof node at the tensioning position: including the anchor pad size, the anchor device model, the tensioning stress value, etc.; the construction parameters of the waterproof node at the anchor head: including the anchor head protection layer thickness, the sealing material type, etc.; the connection relationship data of the anchor rod and the surrounding structure: the contact area and the contact mode of the rod body and the bedrock, the cushion, the raft; the performance parameters of the waterproof material: the flexible waterproof layer thickness, the material permeability coefficient, etc.

[0054] Through the analysis of the collected data, it is found that the original design general construction node has the following problems: the water flow direction of the anti-floating anchor rod body is not effectively blocked, and there is a lack of waterproof measures at the positions where the anchor rod penetrates the cushion and the raft; underground water may penetrate the waterproof layer through the weak joint of the flexible waterproof layer and the prestressed steel bar; the construction quality control points of the waterproof layer are not clear, and it is easy to produce leakage points. Based on the analysis results, two key directions of the waterproof node optimization are determined: the waterproof node treatment scheme of tensioning on the raft is adopted at the tensioning position; the steel plate welding sealing treatment scheme is adopted for the waterproof node at the anchor head.

[0055] S2, in order to establish an accurate BIM model, first, detailed data preparation work is carried out: geometric data processing: the coordinate position data of 1076 anchor rods are imported into the BIM platform, each anchor rod contains X, Y, Z three-dimensional coordinate information; anchor rod geometric parameter standardization: the ordinary section diameter is 200mm, the length is 6000mm; the expanded section diameter is 600mm, the length is 5000mm; raft thickness data: according to different regions, the thickness changes between 800-1200mm; cushion thickness data: the standard thickness is 100mm.

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

[0057] Parameterized modeling method is adopted to realize batch modeling by compiling modeling rules: anchor parameterized modeling: define anchor family file, set variable parameters including anchor length L, ordinary segment diameter D1, expanded body segment diameter D2, inclination angle α; generate 1076 anchor instances through parameter-driven, each instance inherits the geometric rules of the family file; give each anchor a unique number and establish a corresponding relationship with the construction drawings. Waterproof node detail modeling: tensioning site node: establish a detailed model including steel casing (outer diameter 89 mm, wall thickness 4.5 mm), sealing plate (thickness 10 mm), anchor pad (200×200×20 mm); anchor head node: establish a three-dimensional model of 4 mm thick steel plate protection sleeve to ensure accurate expression of the welding relationship with the anchor pad; water stop structure: establish detailed models of water stop wing ring (50×3 mm, spacing 250 mm), expansion water stop strip (20×30 mm cross section).

[0058] S3, according to the actual situation of the project and the requirements of the specification, set the groundwater pressure parameters of two working conditions in the BIM model: normal working condition pressure setting: considering the groundwater level is 85.50 m (normal water storage level), the basement elevation is 74.20 m; the calculated hydrostatic pressure is: P1=ρgh=1000×9.81×(85.50-74.20)=0.11 MPa; considering the dynamic water pressure and safety factor, the normal working condition pressure range is set to 0.3-0.5 MPa; 0.4 MPa is used as the representative value of the normal working condition in the simulation. Limiting working condition pressure setting: considering the once-in-a-century flood level and the rapid rise of groundwater level; the limiting working condition pressure range is set to 0.8-1.0 MPa; 0.9 MPa is used as the representative value of the limiting working condition in the simulation.

[0059] The connection surface between each component is accurately established in the BIM model, which is the key to identifying potential water seepage paths: connection surface definition and mesh division:

[0060] Rod body and bedrock contact surface: expanded body segment surface area = π × 0.6 × 5.0 = 9.42 m²; divided into 942 0.01 m² sub-areas; each sub-area is assigned an independent material property parameter.

[0061] Rod body and cushion contact surface: ordinary segment through the cushion part = π × 0.2 × 0.1 = 0.063 m²; discretized into 63 sub-areas, considering the uneven distribution of construction gaps.

[0062] Prestressed steel bar and grouting body contact surface: steel bar surface area = π × 0.032 × 11.0 = 1.106 m²; divided into 1106 sub-regions, focusing on the density of steel bar threads.

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

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

[0065] Set local material property parameters for each sub-region, which are based on construction quality statistical data and engineering experience:

[0066] Construction gap 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. Assign values to each sub-region through a random distribution function to simulate the unevenness of actual construction.

[0067] Grouting density coefficient β: expanded 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. Use normal distribution 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 material combination type.

[0069] Use the modified Darcy's law to calculate the local permeability coefficient of each sub-region and the equivalent permeability coefficient of the connecting interface : foundation permeability coefficient determination: complete concrete: ; defective concrete: ; modified calculation: , where . For a sub-region of the rod body and bedrock contact surface: α = 0.5, β = 0.85, γ = 2.0; .

[0070] Equivalent permeability coefficient calculation: use the weighted average method to calculate the equivalent permeability coefficient of the entire connecting interface: . The calculation results show that the rod body and bedrock contact surface: ; rod body and cushion contact surface: ; steel casing and raft contact surface: (exceeds the threshold value).

[0071] The CFD module is integrated in the BIM platform. The finite volume method is used for discretization. A single anchor rod is taken as the center, and a cylindrical region with a radius of 2 m is used. The structured grid is used, and the local encryption is performed near the contact surface. The total grid number is about 500,000. The inlet boundary: the main inlet ( greater than ): the pressure of 0.4 MPa (normal working condition) is applied; the secondary inlet ( greater than ): the pressure of 0.32 MPa is applied. The outlet boundary: the anchor head position is set as a free outflow boundary, and the pressure is 0. The anchor rod surface and the surrounding soil are set as a non-slip wall.

[0072] The SIMPLE algorithm is used for pressure-velocity coupling solution. The time step: the initial 0.01 s; the self-adaptive adjustment is performed according to the convergence condition; the convergence criterion: all variable residuals are less than ; the total calculation time: the seepage process of 12 hours is simulated. The following data are output every time step: the velocity field distribution: ; the pressure field distribution: ; the streamline distribution, and the flow change of each monitoring point.

[0073] 2000 tracer particles are released at the main seepage interface, and 1000 tracer particles are released at the secondary seepage interface. The initial speed of the particles is 0, and the particles move with the flow field. The fourth-order Runge-Kutta method is used to solve the particle motion equation, and the time step is 0.001 s. Each particle records the following data: the position coordinate sequence: ; the velocity sequence: , the material region number passed, and the total motion time.

[0074] Through the cluster analysis of 10,000 particle trajectories, four main water leakage channels are identified:

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

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

[0077] The third water leakage channel (accounting for 40% of the total flow): the starting point is the annular gap between the steel casing and the raft, the path is through the thickness of the raft, the end point is the bottom of the anchor head, and the average seepage time is 1.8 hours.

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

[0079] Based on the simulation identification of the four types of water leakage channels, a targeted plugging scheme is developed:

[0080] The first water leakage channel plugging selects water-swelling type sealing strip, specification 20x30mm, expansion rate ≥300%. Installation position: inside the PVC sleeve at the bottom of the anchor rod, 50mm from the bottom end; installation quantity: 2 rows per anchor rod, spacing 100mm; pre-compression rate: 30%, to ensure initial sealing effect; quality control indicators: water injection test within 24 hours after installation, no leakage is required. Through the simulation test of 3 groups of test pieces, the following data is collected: initial state: gap width 2-3mm; after 24 hours of water contact: sealing strip completely fills the gap; pressure capacity: no leakage for 72 hours under 0.6MPa.

[0081] The second water leakage channel plugging uses non-curing rubber asphalt waterproof coating, which has self-healing ability. Plugging process data: coating range: 100mm below the cushion to 100mm above the cushion; coating thickness: 3mm (coated twice); material consumption: 1.5kg / m²; curing time: surface dry 2 hours, real dry 24 hours. Construction process monitoring data: environmental temperature: 15-25℃; relative humidity: ≤80%; coating thickness detection: 9 points per 10m²; continuity detection: use electric spark detection, no leakage points.

[0082] The third water leakage channel plugging, sealing wing ring design data: wing ring specification: width 50mm, thickness 3mm; setting quantity: 2 rows per steel sleeve; spacing: 250mm; welding requirements: full welding, weld height ≥3mm. Welding quality control data: preheating temperature before welding: 150℃; welding current: 120-140A; welding speed: 150-200mm / min; weld detection: 100% ultrasonic detection, 100% pass rate.

[0083] The fourth water leakage channel plugging, treatment range: overlapping parts of the flexible waterproof layer; additional layer setting: width 300mm; overlapping length: ≥100mm; bonding strength: ≥0.7MPa.

[0084] The determined plugging measures are accurately modeled in the BIM model:

[0085] Model update content: sealing strip model: create a parameterized sealing strip family, including shape changes before and after expansion; coating layer model: generate a 3mm thick coating layer through face domain offset function; sealing wing ring model: accurately model the weld shape for engineering quantity statistics; waterproof additional layer: establish a model of the overlapping relationship of multiple layers of waterproof membrane.

[0086] Re-perform CFD simulations on the BIM model that includes the blocking measures:

[0087] Simulation results: First leakage channel: flow rate reduced by 99.8%, essentially blocked; Second leakage channel: flow rate reduced by 99.5%, effectively blocked; Third leakage channel: flow rate reduced by 99.9%, completely blocked; Fourth leakage channel: flow rate reduced by 99.6%, effectively controlled.

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

[0089] Based on the optimized BIM model, such as Figure 2 As shown, construction drawings are automatically generated. During the construction of 1076 anti-buoyancy anchors, a complete data monitoring system was established: Quality inspection data summary: Waterstop ring weld inspection: 1076×2=2152 welds, 100% pass rate; Coating thickness inspection: 200 samples were inspected, average thickness 3.2mm, standard deviation 0.15mm; Waterproof membrane overlap: 500 samples were inspected, overlap length ≥100mm. On-site test data: Water injection test: All 1076 anchors were pressure-held at 0.5MPa for 24 hours; Test results: No leakage, 100% success rate; Long-term monitoring: Retesting after 6 months of operation, still maintaining a 100% waterproof rate.

[0090] The foregoing illustrative description of the present application and its embodiments is not restrictive and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. The accompanying drawings are only one embodiment of the present application, and the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present application, such designs should fall within the scope of protection of this application. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" preceding an element does not exclude the inclusion of "a plurality" of that element. Terms such as "first," "second," etc., are used to indicate names and do not indicate any specific order.

Claims

1. A BIM-based anti-floating anchor rod construction method, characterized by, The method comprises the following steps: S1, obtaining an initial waterproof joint design scheme of the prestressed anti-floating anchor rod, the waterproof joint comprising a tensioning part waterproof joint and an anchor head waterproof joint; S2, establishing a BIM model of the prestressed anti-floating anchor rod according to the initial waterproof joint design scheme; S3, simulating water seepage conditions of the prestressed anti-floating anchor rod under different groundwater pressures by using the BIM model, and identifying potential water leakage channels; S4, according to the simulation results, different sealing treatments are performed on the identified potential water leakage channels, including: for a first water leakage channel through which groundwater reaches the anchor head along the inside of the prestressed reinforcement through the bottom of the rod body, an expansion waterstop is used for sealing; for a second water leakage channel through which groundwater reaches the anchor head along the outside of the rod body through the rod body and the cushion, non-solidified asphalt is used for sealing; for a third water leakage channel through which groundwater reaches the anchor head by penetrating the raft through the rod body inside the raft, a water stop wing ring is welded outside the steel casing pipe for sealing; for a fourth water leakage channel through which groundwater reaches the anchor head along the prestressed reinforcement at the joint of the flexible waterproof layer and the prestressed reinforcement, non-solidified asphalt is used for sealing; S5, setting corresponding sealing measures in the BIM model to obtain a BIM model containing the sealing measures; S6, generating waterproof joint construction drawings by using the BIM model containing the sealing measures to guide the on-site construction; wherein the identification of the potential water leakage channels comprises: setting groundwater pressure parameters in the BIM model, the groundwater pressure parameters comprising normal working condition pressure and extreme working condition pressure; establishing connecting surfaces between components of the prestressed anti-floating anchor rod in the BIM model, the connecting surfaces comprising: a rod body and bedrock contact surface, a rod body and cushion contact surface, a prestressed reinforcement and grouting body contact surface, a flexible waterproof layer and prestressed reinforcement contact surface, and a steel casing pipe and raft contact surface; under the action of the groundwater pressure parameters, the seepage coefficients of groundwater through each connecting surface are calculated by the BIM model, when the seepage coefficient is greater than a preset threshold value, the corresponding connecting surface is determined as a potential water seepage interface, including: discretizing each connecting surface into a plurality of sub-regions in the BIM model; for each sub-region, corresponding local material attribute parameters are set, the local material attribute parameters comprising: construction gap distribution density coefficient α, grouting compactness coefficient β, and interface roughness coefficient γ; The local permeability coefficients of each sub-region are calculated using the modified Darcy's law and the equivalent permeability of the corresponding connection interface : where, A, is the area of the ith sub-region, is the weight coefficient, , Kmaxis the maximum permeability coefficient among all sub-regions; where Q is the unit time seepage flow, L is the seepage path length, and ΔP is the pressure difference. When the local permeability coefficient is greater than or the equivalent permeability coefficient is greater than , the corresponding connecting interface is determined as a potential water seepage interface. according to the potential water seepage interface, the seepage path of the groundwater is simulated by the BIM model; according to the starting position and flow direction of the seepage path, the potential water leakage channel is divided into the first to fourth water leakage channels.

2. The BIM-based anti-floating anchor rod construction method according to claim 1, wherein: the tensioning part waterproof joint is treated by a raft tensioning waterproof joint; the anchor head waterproof joint is treated by a steel plate welding sealing treatment.

3. The BIM-based anti-floating anchor rod construction method according to claim 1, wherein: the normal working condition pressure is 0.3MPa to 0.5MPa; the extreme working condition pressure is 0.8MPa to 1MPa.

4. The BIM-based anti-floating anchor rod construction method according to claim 1, wherein: according to the potential water seepage interface, the seepage path of the groundwater is simulated by the BIM model, including: integrating a computational fluid dynamics (CFD) module in the BIM model. Set groundwater inlet boundary condition: Set the area with local hydraulic conductivity greater than as the primary inlet, set the area with equivalent hydraulic conductivity greater than as the secondary inlet, and set the anchor head location as the outlet boundary; According to the set groundwater pressure parameter, a corresponding working condition pressure is applied at the inlet boundary condition; A computational fluid dynamics (CFD) module is used to solve the velocity field and pressure field distribution of the groundwater based on the Darcy-Brinkman equation; According to the velocity field and pressure field distribution, the flow line tracking is performed by the particle tracking method to obtain the seepage path of the groundwater from each potential water seepage surface to the anchor head; According to the starting position and flow direction of the seepage path, the potential water leakage channel is divided into the first to fourth water leakage channels.

5. The BIM-based anti-floating anchor construction method according to claim 4, characterized in that: According to the set groundwater pressure parameter, a corresponding working condition pressure is applied at the inlet boundary condition, including: Under normal operating conditions, a pressure of 0.3 MPa to 0.5 MPa is applied at the primary inlet A pressure is applied at the secondary inlet of 80%; Under extreme conditions, 0.8 MPa to 1.0 MPa pressure is applied at the primary inlet 80% of the pressure applied at the secondary inlet is applied at the primary inlet.

6. The BIM-based anti-floating anchor construction method according to claim 4, characterized in that: A computational fluid dynamics (CFD) module is used to solve the velocity field and pressure field distribution of the groundwater based on the Darcy-Brinkman equation, including: The local permeability coefficient Ki is converted into a corresponding permeability parameter, and a heterogeneous seepage field is established according to the permeability parameter; A computational fluid dynamics (CFD) module is used to solve the velocity field and pressure field distribution of the groundwater based on the Darcy-Brinkman equation.

7. A BIM-based anti-floating anchor rod construction system, characterized by, It includes: A node design module obtains an initial waterproof node design scheme of the prestressed anti-floating anchor, and the waterproof node includes a tension part waterproof node and an anchor head waterproof node; A BIM modeling module establishes a BIM model of the prestressed anti-floating anchor according to the initial waterproof node design scheme; A water seepage simulation module simulates the water seepage of the prestressed anti-floating anchor under different groundwater pressure conditions by using the BIM model, and identifies a potential water leakage channel; A plugging treatment module processes the identified potential water leakage channel by using different plugging measures according to the simulation result; A parameter updating module sets corresponding plugging measures in the BIM model to obtain a BIM model containing the plugging measures; A drawing generation module generates a waterproof node construction drawing by using the BIM model containing the plugging measures to guide the on-site construction; Wherein, the potential water leakage channel is identified, including: Groundwater pressure parameters are set in the BIM model, including normal working condition pressure and limit working condition pressure; Connection surfaces between components of the prestressed anti-floating anchor are established in the BIM model, including: a rod body and bedrock contact surface, a rod body and cushion contact surface, a prestressed steel and grouting body contact surface, a flexible waterproof layer and prestressed steel contact surface, and a steel casing and raft contact surface; Under the action of the groundwater pressure parameter, the BIM model is used to calculate the permeability coefficient of the groundwater through each connection surface, and when the permeability coefficient is greater than a preset threshold value, the corresponding connection surface is determined as a potential water seepage interface, including: Each connection surface is discretized into a plurality of sub-regions in the BIM model; For each sub-region, corresponding local material attribute parameters are set, including: construction gap distribution density coefficient α, grouting compactness coefficient β, and interface roughness coefficient γ; The local permeability coefficients of each sub-area are calculated using the modified Darcy's law and the equivalent permeability of the corresponding connection interface : where, A, is the area of the ith sub-area, is the weighting coefficient, , Kmaxis the maximum permeability coefficient among all sub-areas; where Q is the unit time seepage flow, L is the seepage path length, and ΔP is the pressure difference. When the local permeability coefficient is greater than or the equivalent permeability coefficient is greater than , the corresponding connecting interface is determined as a potential water seepage interface. According to the potential water seepage interface, the seepage path of the groundwater is simulated by the BIM model; The potential water leakage passage is divided into first to fourth water leakage passages according to the starting position and the flow direction of the seepage path.

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