Method for positioning and laying precast floating slabs in curved sections

Abstract

This invention relates to the field of urban rail transit track construction technology, and provides a method for positioning and laying precast floating slabs in curved sections. The method includes: establishing the line benchmark and slab joint projection edge based on CPⅢ control points to determine the fan-shaped slab joint difference; determining the theoretical offset using the mid-vector method, superimposing the additional offset caused by superelevation, and incorporating the internal sliding compensation amount during slab lifting to obtain the comprehensive offset for theoretical positioning; after the slab is suspended and placed, fine-tuning it to within a threshold matching the specifications of the leveling shims in a non-lifting state; and installing lateral supports after fine-tuning to resist inward sliding during slab lifting. This invention upgrades traditional trial-and-error based experience to an active positioning control system with multi-factor coupled calculation, solving the millimeter-level positioning problem of rigid slabs under the coupled effects of curve constraints, cross slope projection, and slab lifting disturbances. It eliminates the inefficient cycle of fine-tuning, lifting, sliding, and readjustment, significantly improving construction efficiency and quality consistency.

Description

Technical Field

[0001] This invention relates to the field of urban rail transit track construction technology, and in particular to a method for positioning and laying precast floating slabs in curved sections. Background Technology

[0002] Floating slab track structures, by inserting vibration isolators between the track bed and the foundation to form a "mass-spring" vibration isolation system, are a core technology for vibration reduction and noise reduction in urban rail transit. Among them, steel spring floating slabs have become the preferred solution for special vibration reduction sections due to their low natural frequency and significant vibration reduction effect. Prefabricated assembled floating slabs adopt a standardized factory production and on-site mechanical assembly mode, which has the advantages of controllable quality, shortened construction period, and low labor intensity.

[0003] However, the precise positioning and laying of precast floating slabs on curved sections faces significant technical bottlenecks. The precast unit slabs are rectangular, while the curved sections of the track are circular, resulting in fundamental differences in geometry: the slab joints exhibit a fan-shaped variation with smaller inner joints and larger outer joints; the slab centerline deviates from the track centerline; track superelevation causes additional offsets of varying magnitudes on the upper and lower surfaces of the slab; and the lifting process introduces further horizontal displacement. These factors interact, making the positioning accuracy control on curved sections far more complex than on straight sections.

[0004] Traditional solutions have the following limitations: The bisecting mid-sagittal method, widely used in traditional railway curve laying, works well in ordinary ballasted tracks or cast-in-place ballast beds, but it cannot be directly applied to precast floating slab construction. This is because ordinary track panels are flexible structures, and cast-in-place ballast beds are continuous, allowing subsequent processes to absorb curve deviations. However, precast floating slabs are rigid rectangular plates; once their position is determined, they cannot be fine-tuned. Furthermore, a jacking process is required after laying, and the horizontal component of the force generated by the compression and rebound of the vibration isolators causes the slab to tend to slide inwards. This leads to repeated adjustments, jacking, and readjustment, severely impacting construction efficiency.

[0005] While the CPⅢ precision measurement technology for high-speed rail can achieve millimeter-level track fine-tuning, there are still compatibility issues when it is applied to the construction of floating slabs for subways: high-speed rail track slabs do not have a lifting process, and the fine-tuning results are the final results; however, subway floating slabs require lifting after fine-tuning, and the mechanical response causes the fine-tuning results to drift, forming an additional cycle.

[0006] Traditional construction specifications for the laying of floating slabs in curved sections are rather general and lack operational quantitative guidance. When faced with specific issues such as the amount of superelevation, offset, and allowance, construction workers lack clear calculation basis and rely on experience-based estimations, leading to: inconsistent control of slab joints and excessive cumulative errors; insufficient estimation of slippage within the slab in superelevation sections, resulting in slab joints being squeezed or torn after jacking; and untimely installation of lateral supports, causing slab instability during jacking. Summary of the Invention

[0007] The purpose of this invention is to solve at least one technical problem in the background art and to provide a method for positioning and laying prefabricated floating slabs in curved sections.

[0008] To achieve the above objectives, the present invention provides a method for positioning and laying precast floating slabs in curved sections, comprising the following steps: S1. Establish the line benchmark, and set up the line centerline control stakes based on the CPⅢ control points. Set up one control stake at a preset distance in the curved section and set up the five major stake points of the curve. Set up the center control stake of the slab joint and the projected edge line of the precast unit slab according to the length of the precast unit slab. The slab joint in the curved section is fan-shaped. The slab joint at the line centerline is the design value. The difference between the slab joint on the inner side and the outer side of the curve is determined by the line radius and the slab length. S2. Calculate the theoretical offset. The theoretical offset between the centerline of the precast unit slab and the centerline of the track is determined using the bisecting mid-vector method. This theoretical offset is half of the total vector of the curve. Based on this, the additional offset caused by superelevation is superimposed. The additional offset is determined by the product of the vertical distance from the track reference point to the surface of the precast unit slab and the superelevation according to a proportional coefficient. The additional offset of the upper surface of the precast unit slab is less than that of its lower surface, and both are offsets in the same direction outward from the track. At the same time, the compensation amount for the inward sliding of the precast unit slab caused by the lifting process of lifting the precast unit slab is included to obtain the comprehensive offset. S3. Theoretical positioning: Starting from the track reference point, determine the theoretical center position of the prefabricated unit plate along the direction of the comprehensive offset; hoist the prefabricated unit plate above the base, so that the center line of the plate coincides with the theoretical center position, the outline of the plate coincides with the projected edge line, and reserve lifting operation space between the plate and the base. S4. Fine-tuning positioning: With the plate not lifted, use auxiliary measuring tools to measure the lateral position deviation of the plate; based on the difference between the measured deviation and the theoretical offset, use jacks to adjust the position of the plate until the deviation between the measured position and the theoretical position is controlled within the allowable range. S5. Maintain stability. After the slab is adjusted to the correct position on curved sections, install lateral supports. For sections with a superelevation greater than the preset value, install at least one support for each slab to resist the tendency of the slab to slip along the curve during the lifting process.

[0009] According to one aspect of the present invention, the method for calculating the additional offset includes: Additional offset on the upper surface of the prefabricated unit panel: ; Additional offset on the lower surface of the prefabricated unit panel: ; In the formula, This is the vertical distance from the track reference point to the surface of the precast unit plate; This is the vertical distance from the track reference point to the lower surface of the precast unit slab; This refers to the orbital superelevation value. For track gauge; The upper surface has an additional offset. Less than the additional offset of the lower surface Both are deflected outwards from the track.

[0010] According to one aspect of the invention, the compensation amount is a reserve amount for the inward sliding of the plate during the lifting process.

[0011] According to one aspect of the present invention, the method for determining the plate joint difference is as follows: The curved section of the line is an arc, and the prefabricated unit panels are rectangular. When the rectangular panels are spliced ​​along the arc, the panel seam forms a fan shape with a smaller inner part and a larger outer part. The precast unit slab is considered as a chord on the centerline of the curved section of the railway line, and the maximum distance between the chord and the arc formed by the curved section of the railway line is the moment of inflection. Since the precast unit slabs are rectangular, the slab gap difference 'e' generated on the inner and outer sides of the line in curved sections is considered to be determined by the superposition effect of the two-end distances, i.e., twice the single-sided distance 'F'. Therefore, the slab gap difference 'e' is calculated using the following formula: ; In the formula: L is the length of the prefabricated unit panel, and R is the radius of the curved section; The inner side plate seam of the curve The outer side plate seam of the curve , where a is the design value of the plate joint at the center line of the line.

[0012] According to one aspect of the present invention, the following method is used to eliminate accumulated errors during the laying of prefabricated unit panels: Four consecutive prefabricated unit panels are used as one error elimination unit; The first precast unit panel within the unit is positioned according to the theoretical panel joint. After the second precast unit slab is laid, the actual joint between the first and second precast unit slabs is measured, and the deviation between the actual joint and the theoretical joint is recorded as follows: ; When laying the third precast unit slab, the gap between it and the second precast unit slab should be adjusted to the theoretical value minus [the value is missing from the original text]. This ensures that the cumulative length from the first prefabricated unit panel to the third prefabricated unit panel matches the theoretical cumulative length. When laying the fourth precast unit panel, the gap between it and the third precast unit panel is adjusted to the theoretical value. At the same time, the total length from the first precast unit panel to the fourth precast unit panel is measured. If there is a remaining deviation between the total length and the theoretical total length, the remaining deviation is allocated to the gap between the third and fourth precast unit panels. The next unit starts from the 5th precast unit slab, repositions itself according to the theoretical slab seam, and repeats the above operation.

[0013] According to one aspect of the invention, the lateral support is installed after the plate is finely adjusted and before the lifting process begins, so as to resist the slippage of the plate towards the inside of the curve during the lifting process.

[0014] According to one aspect of the present invention, the method for reserving the lifting operation space is as follows: a rigid square wooden board of a predetermined thickness is placed between the board and the base, so that the board is in a suspended state.

[0015] According to one aspect of the present invention, when the method is applied to a circular tunnel or a rectangular tunnel, the calculation of the additional offset is based on the vertical distance from the corresponding track reference point to the upper and lower surfaces of the precast unit plate selected according to the tunnel cross-section form. The vertical distance between the corresponding circular tunnels is greater than the vertical distance between the corresponding rectangular tunnels.

[0016] According to one aspect of the invention, the allowable range is that both longitudinal and lateral positioning errors are less than or equal to a threshold, which is matched with the specifications of the leveling shims of the vibration isolator after jacking.

[0017] According to the present invention, a method for positioning and laying precast floating slabs in curved sections is disclosed. Its core lies in constructing a three-in-one spatial attitude pre-correction construction system based on static geometric adaptation, dynamic mechanical prediction, and process boundary constraints. This method first establishes a line benchmark based on the CPⅢ precision control network, surveys the five major pile points of the curve and the projected edges of the slab joints, discretizes the continuous circular arc into independent placement domains for rectangular slabs, and determines the internal and external distribution rules of the fan-shaped slab joints based on the slab joint difference formula. On this basis, an innovative comprehensive offset calculation model is proposed: the curve geometric offset is determined using the bisecting mid-vector method, the differential additional offset of the upper and lower surfaces of the slab caused by track superelevation is superimposed, and the internal sliding compensation amount of the slab caused by the jacking process is actively included, unifying the heterogeneous displacements into the same vector coordinate system to complete the theoretical positioning calculation. After the slab is hoisted, a pre-thickness pad is placed between the base and the slab to achieve suspended coarse positioning, which eliminates the interference of nonlinear friction of the base on the fine-tuning accuracy and reserves vertical travel space for subsequent jacking. The fine-tuning process is limited to the static, suspended state before jacking. Jacks are used to correct the lateral deviation of the slab to a threshold range matching the specifications of subsequent leveling shims, thus eliminating the influence of jacking dynamics variables on measurement stability. After fine-tuning is achieved, lateral supports are installed before the jacking process begins. These passively resist the transient horizontal sliding force pointing inwards towards the curve during jacking, locking the fine-tuning results into the final supported state without damage. This invention upgrades the laying of precast floating slabs in curved sections from the traditional passive correction mode relying on trial and error to an active positioning control system based on multi-factor coupled calculations. This solves the millimeter-level positioning problem of rigid rectangular slabs under the triple coupling of curve geometric constraints, cross slope tilt projection errors, and jacking dynamic disturbances. It fundamentally eliminates the inefficient construction cycle of fine-tuning, jacking, sliding, and readjustment, significantly improving construction efficiency and overall quality consistency. Attached Figure Description

[0018] Figure 1 The flowchart schematically illustrates a method for positioning and laying precast floating slabs in curved sections according to an embodiment of the present invention. Detailed Implementation

[0019] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0020] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0021] Figure 1 This is a schematic flowchart illustrating a method for positioning and laying precast floating slabs in curved terrain according to an embodiment of the present invention. Figure 1 As shown in this embodiment, the method for positioning and laying precast floating slabs in curved sections includes the following steps: S1. Establish the line benchmark, and set up the line centerline control stakes based on the CPⅢ control points. Set up one control stake at a preset distance in the curved section and set up the five major stake points of the curve. Set up the center control stakes of the slab joints and the projected edge lines of the precast unit slabs according to the length of the precast unit slabs (precast floating slabs). The slab joints in the curved section are fan-shaped. The slab joints at the line centerline are the design values. The difference between the slab joints on the inner and outer sides of the curve is determined by the line radius and the slab length. S2. Calculate the theoretical offset. The theoretical offset between the centerline of the precast unit slab and the centerline of the track is determined using the bisecting mid-vector method. This theoretical offset is half of the total vector of the curve. On this basis, the additional offset caused by superelevation is superimposed. The additional offset is determined by the product of the vertical distance from the track reference point to the surface of the precast unit slab and the superelevation according to a proportional coefficient. The additional offset of the upper surface of the precast unit slab is less than that of its lower surface. Both are offsets in the same direction outward from the track. At the same time, the compensation amount for the inward sliding of the precast unit slab caused by the lifting process of lifting the precast unit slab is included to obtain the comprehensive offset. S3. Theoretical positioning: Starting from the track reference point, determine the theoretical center position of the prefabricated unit plate along the direction of the comprehensive offset; hoist the prefabricated unit plate above the base, so that the center line of the plate coincides with the theoretical center position, the outline of the plate coincides with the projected edge line, and reserve lifting operation space between the plate and the base. S4. Fine-tuning positioning: With the plate not lifted, use auxiliary measuring tools to measure the lateral position deviation of the plate; based on the difference between the measured deviation and the theoretical offset, use jacks to adjust the position of the plate until the deviation between the measured position and the theoretical position is controlled within the allowable range. S5. Maintain stability. After the slab is adjusted to the correct position on curved sections, install lateral supports. For sections with a superelevation greater than the preset value, install at least one support for each slab to resist the tendency of the slab to slip along the curve during the lifting process.

[0022] In this embodiment, step S1 establishes a three-level control benchmark from macroscopic alignment to microscopic slab position by introducing the CPⅢ precision control network for free station intersection measurement and densifying the five major stake points of the curve and the projected edge line of the slab joint. Its technical effect lies firstly in discretizing the continuous circular arc line into a series of rectangular slab placement domains with independent positioning boundaries: the centerline control stakes of the line measured based on the CPⅢ control points determine the absolute direction of the line; the five major stake points of the curve lock the key nodes of curvature change; and the center control stakes of the slab joint and the projected edge line of the precast unit slab, measured according to the length of the precast unit slab, fit the theoretically smooth curve into a polygon approximation, defining the independent positioning domain of each precast slab from the source. Secondly, this step clarifies the geometric determinants of the difference between the inner and outer slab joints of the curve: the line radius and the slab length. Its effect is to provide precise planar positioning boundaries and slab end attitude prediction basis for each precast slab. In curved sections, the slab joints are fan-shaped, with the joint width at the centerline of the track set at the design value. This allows construction personnel to predict the width variation trend of each joint, avoiding slab corner abutments or excessive gaps due to geometric mismatches. Control stakes, using cross-shaped stainless steel base markers, are installed on the centerline of the track, ensuring the long-term stability and repeatability of the benchmark, providing a reliable measurement basis for subsequent fine-tuning.

[0023] Step S2 defines the calculation structure of the comprehensive offset, and its core contribution lies in unifying the three heterogeneous displacements into the same spatial vector coordinate system. First, the introduction of the bisecting mid-vector method establishes the static ideal position of the rigid slab on the circular curve. This method coincides the midpoint of the curve's chord with the midpoint of the circular arc, ensuring that the laying units are evenly distributed on both sides of the curve. For precast unit slabs, the slab centerline is the chord, the track centerline is the circular arc, and the theoretical offset of the slab centerline relative to the track centerline is half of the total vector F of the curve (…). ,in This offset solves the geometric reference problem of how a rectangular slab can fit into a curve, and is the fundamental quantity for slab positioning in curved sections. Second, the superposition of the superelevation offset breaks through the limitation of traditional track laying that only considers the superelevation of the rail surface and ignores the rigid body tilt projection of the slab. The track superelevation makes the base form an inclined surface. After the slab is placed on it, the center points of the upper and lower surfaces are both horizontally offset outward from the track reference point (the center of the rail surface), but the offset amplitudes are different. The effect is to reveal the projection law of the slab "drifting up and down" under the cross slope. Since the vertical distance between the lower slab surface and the track reference point is greater than that of the upper slab surface, the additional offset of the lower surface is greater than that of the upper surface. Incorporating this difference into the calculation allows the positioning reference to accurately distinguish the projection difference between the top and bottom of the slab, and to convert the vertical projection deviation caused by the slab thickness into a calculable offset component. Third, the inclusion of the lifting compensation is the most creative effect of step S2. After the floating slab is laid, a jacking process is required: hydraulic jacks are placed at the four corners of the slab to lift it to the design elevation. The vibration isolators then compress and rebound, supporting the slab at the design height. During the jacking process, the rebound force generated by the compression of the vibration isolators decomposes into a horizontal component pointing inwards in curved sections, causing the slab to tend to slide inwards. This difference cannot be accurately determined through static geometric calculations, but this invention predicts the mechanical response of the subsequent dynamic jacking in the theoretical offset. By pre-offsetting the centerline of the slab to the outside of the curve by a certain distance (compensation amount) during the fine-tuning stage, the inward sliding of the slab after experiencing the jacking disturbance precisely offsets the pre-offset amount, automatically returning it to the design coordinates.

[0024] The above three factors are integrated into a comprehensive offset: theoretical offset ( The system includes three offsets: outward track, additional offset (outward track), and compensation (outward track, pre-offset). During actual positioning, the combined offset of the track reference point to the outward track is the center position of the slab. This step directly eliminates the inefficient cycle of fine-tuning, jacking and sliding, and readjustment, elevating empirical estimation to calculable deterministic pre-control.

[0025] Step S3 defines the initial state after hoisting. The prefabricated unit panels are hoisted above the base, ensuring the panel's centerline coincides with the theoretical center and the panel's outline coincides with the projected edge line. This achieves a smooth transition from the hoisting state to the positioning state. Based on this, a lifting operation space is reserved between the panel and the base. Pads are placed to keep the panel suspended, creating ideal boundary conditions before fine-tuning. This design achieves two key functions: First, controllable frictional resistance. After the panel separates from the base, the friction interface during lateral adjustment shifts from the irregular base surface to the controllable temporary pad contact surface. The frictional force originates only from the product of the panel's self-weight and the pad's friction coefficient, eliminating nonlinear resistance fluctuations caused by base unevenness and establishing a stable linear relationship between the jack's displacement input and the panel's response. Second, stress release. The suspended state allows the panel to freely adapt to temperature deformation or minute geometric tolerances, preventing internal locking stress caused by forced descent and ensuring the structure's initial zero-stress state before vibration isolator installation.

[0026] Step S4 emphasizes completing fine-tuning while the plate is not lifted. Its underlying technical logic lies in eliminating the interference of the nonlinear stiffness rebound of the vibration isolators during the lifting process on measurement stability. If fine-tuning is performed after lifting, the rebound force of the vibration isolators will cause the plate to be in a state of stress-induced floating, resulting in unstable measurement data. In the static, suspended state before lifting, rigid displacement correction is performed using jacks. Lateral deviations are achieved through symmetrical jacking and retraction on both sides, while angular deviations are achieved through differential jacking at the four corners to achieve minute rotations. The effect is to obtain unique, stable, and repeatable true lateral coordinates. The goal of fine-tuning is to control the deviation between the measured position and the theoretical position within the allowable range. This approach ensures that the theoretical offset calculated in step S2 is materialized without distortion, avoiding the drift of fine-tuning results due to subsequent lifting procedures, and establishing a traceable correspondence between the precision measurement results and the final stable state.

[0027] Step S5 specifies the installation logic of lateral supports: Lateral supports are installed on curved sections after the slab is adjusted to its position; on sections with superelevation exceeding a preset value, at least one support is installed for each slab. Its technical effect is to provide a directional reaction force device for the instantaneous dynamic load during the jacking process. On superelevated curved sections, the slab is placed on an inclined base. During the jacking process, the vertical upward rebound force generated by the compression of the vibration isolators forms a non-orthogonal relationship with the slab plane. This rebound force is decomposed into a horizontal component pointing towards the inside of the curve within the slab plane, causing the slab to tend to slide towards the inside of the curve. Installing lateral supports at this time does not simply block the slab, but rather passively compresses and counteracts this horizontal component, converting the horizontal movement trend during the jacking process into the elastic strain energy of the support system. The compensation amount reserved in step S2 is essentially a preset geometric tolerance for the stress deformation of the support system and the micro-contact adjustment of the slab bottom, rather than an active sliding stroke.

[0028] The supports are installed after fine-tuning and before jacking begins, ensuring that the slab can move freely during the fine-tuning phase, while the tendency to slip during jacking is restrained before it occurs. This restraint ensures that the slab can only rise vertically during the jacking instant, solving the persistent engineering problems of slab instability and slab joint jamming during jacking.

[0029] The above five steps constitute a logically closed-loop spatial attitude pre-correction construction scheme. This scheme upgrades the precast floating slab laying process in curved sections from an experience-based, trial-and-error, and passive correction mode to an active positioning control system based on multi-factor coupled calculation. This method enables the rigid rectangular slab to accurately land within the design threshold range in one go, even under the triple coupling effects of curve geometric constraints, cross slope tilt projection errors, and jacking dynamic disturbances. This significantly improves construction efficiency and quality consistency, and solves the technical challenge of millimeter-level positioning of precast slabs under complex working conditions.

[0030] Furthermore, according to one embodiment of the present invention, the method for calculating the additional offset includes: Additional offset on the upper surface of the prefabricated unit panel: ; Additional offset on the lower surface of the prefabricated unit panel: ; In the formula, This is the vertical distance from the track reference point to the surface of the precast unit plate; This is the vertical distance from the track reference point to the lower surface of the precast unit slab; This refers to the orbital superelevation value. For track gauge; Additional offset on the upper surface Less than the additional offset of the lower surface Both are deflected outwards from the track.

[0031] In this embodiment, track superelevation is the elevation of the outer rail to balance the centrifugal force of the train. In floating slab structures, this is typically achieved on the track bed base, i.e., the base surface is inclined. After the prefabricated unit slab is placed on the inclined base, the slab itself remains horizontal, but its geometric centerline is horizontally offset relative to the track reference point (usually located at the center of the rail surface). Formula and The physical nature of this offset is revealed by a simple linear relationship: the offset is proportional to the superelevation h and to the vertical distance from the track reference point to the plate surface. or It is directly proportional to the track gauge S and inversely proportional to the superelevation angle. The proportionality coefficient h / S essentially represents the tangent of the superelevation angle. Under small angle conditions (superelevation of subway lines typically does not exceed 120mm, corresponding to a superelevation angle of approximately...), it is... ), Therefore It can also approximate the sine value of the superelevation angle, giving the formula a clear geometric meaning.

[0032] The above formula directly derives a key feature: due to the vertical distance between the lower plate surface and the track reference point... It must be greater than the vertical distance from the top surface. Therefore, an additional offset is added to the lower surface. Always greater than the additional offset of the upper surface Both are offset in the same direction towards the outward track. This quantitative difference cannot be revealed by traditional "mid-vector bisecting method" or empirical estimation. Taking a typical working condition with a standard plate thickness of 340mm as an example, , When super high ,gauge hour, , The difference between the two is 27.2 mm. This magnitude of difference means that if the construction workers use the upper surface as the positioning reference for fine-tuning, while the actual support surface of the slab after jacking is near the lower surface, the final stable position will experience an uncontrollable drift of nearly 3 cm. The above formula allows the construction workers to accurately calculate the corresponding offset based on the actually selected positioning reference surface (upper or lower surface), fundamentally avoiding systematic errors caused by misalignment of the reference surface.

[0033] The above input parameters , , , All values ​​are definite and can be directly obtained from design drawings or on-site measurements, without relying on empirical coefficients or on-site calibration. This characteristic makes the calculation of additional offsets reproducible and consistent in construction. Different work teams and different sections can obtain uniform offsets by calculating using the same formula, eliminating the dispersion of manual estimation.

[0034] The additional offset is one of the core components of the composite offset. Once defined as a definite linear function, the calculation of the composite offset has a solid mathematical foundation. Additional offset on the upper surface. Additional offset to the lower surface The clear distinction also provides parameter basis for the two-stage control strategy during construction, which uses the upper surface as a reference for initial positioning and the lower surface support surface as the standard for final verification. This formula transforms the spatial tilt effect caused by superelevation from vague empirical judgment into a standard process that can be substituted into calculations, enabling the positioning of precast floating slabs in curved sections to shift from passively adapting to errors to actively calculating and compensating for them.

[0035] In this embodiment, the additional offset calculation formula reveals the asymmetric law of the offset between the upper and lower surfaces of the slab under ultra-high working conditions with a clear linear function, quantifies the positioning deviation caused by the difference in the selection of reference surfaces, upgrades the traditional experience-based fuzzy correction to a calculable pre-control based on design parameters, and provides a key theoretical calculation basis for the accurate laying of precast floating slabs in curved sections.

[0036] Furthermore, according to one embodiment of the present invention, the compensation amount is the allowance for the plate to slide inward during the lifting process.

[0037] In this embodiment, the core feature distinguishing floating slab laying from ordinary precast slabs lies in the process sequence of fine-tuning followed by jacking. During the jacking process, hydraulic jacks apply vertical forces at the four corners of the slab, causing the vibration isolators to compress and ultimately rebound to support the slab. In this process, the rebound force generated by the compression of the vibration isolators is not purely vertical; because the slab is placed on an extremely steep inclined base, the rebound force is decomposed into a horizontal component pointing inwards towards the curve within the slab plane. Furthermore, factors such as the fit clearance between the vibration isolator sleeve and the positioning pin, the micro-friction state between the slab and the temporary pads, and the squeezing effect of the slab gaps all cause the stable position of the slab after jacking to irreversibly drift inwards towards the curve relative to the fine-tuned position. This invention explicitly defines this drift as an object that needs to be reserved, incorporating the jacking dynamics effect into the explicit variables of the positioning calculation in the construction method.

[0038] The core idea behind this approach is not to eliminate lifting slippage (which is physically unavoidable), but rather to proactively pre-offset the slab's centerline outwards by a compensation amount during the fine-tuning phase. This ensures that the inward slippage of the slab after lifting precisely offsets this pre-offset value, resulting in a stable position that automatically approximates the theoretical design position. The engineering value of this strategy lies in transforming uncontrollable errors into controllable parameters. The specific value of the compensation amount is determined based on on-site lifting and commissioning estimations. The estimation method involves fine-tuning, lifting, and re-measuring the first test slab in a similar location (same radius, same superelevation), measuring the positional change before and after lifting, and using this as the basis for determining the compensation amount in subsequent similar locations. This method condenses the highly discrete and complex dynamic response into a deterministic reserved value through on-site calibration, making the positioning of subsequent slabs reproducible. Although the compensation amount itself originates from empirical calibration rather than theoretical formula derivation, once its value is determined, it is used as a fixed parameter in similar locations, thus achieving a leap in efficiency from trial and error for each slab to calibration only once and batch application.

[0039] The introduction of compensation, together with the theoretical offset determined by the bisecting mid-vector method and the additional offset calculated by the superelevation formula, constitutes the comprehensive offset. In this architecture, the compensation plays a unique role: the theoretical offset and the additional offset solve the static geometric problem: the ideal position of the slab under no external force disturbance; the compensation solves the dynamic mechanical problem: the positional drift after the intervention of the jacking force. The combination of the two upgrades the positioning calculation of the precast floating slab from a simple geometric adaptation to a coupled analysis of geometry and mechanics. As the dynamic component of the comprehensive offset, the compensation's outward pre-offset direction is set opposite to the physical direction of inward sliding. This reverse pre-offset strategy is an active control logic proposed for the first time in this field.

[0040] Without a compensation strategy, after fine-tuning, construction workers would lift the slab and find it had slipped inwards beyond the tolerance. This would necessitate depressurization, lowering, readjustment, and lifting again, creating an inefficient cycle of fine-tuning, lifting, slippage, lowering, and readjustment. The introduction of compensation allows the initial fine-tuning to include the anticipation of lifting and slippage. After lifting, the slab automatically slips to near the design position, and the remaining deviation usually falls within the lateral adjustment capability of the vibration isolator, eliminating the need for secondary hoisting or significant adjustments.

[0041] Furthermore, according to one embodiment of the present invention, the method for determining the plate seam difference is as follows: The curved section of the railway line is an arc, and the precast unit panels are rectangular. When the rectangular panels are spliced ​​along the arc, the joints form a fan shape with a smaller inner diameter and a larger outer diameter. The joint difference e is calculated using the following formula: ; In the formula: L is the length of the prefabricated unit panel, and R is the radius of the curved section; inner side panel seam of the curve Curved outer plate seam , where a is the design value of the plate joint at the center line of the line.

[0042] In this embodiment, the curved section of the railway line is an arc, while the prefabricated unit slabs are rectangular, resulting in a fundamental difference in their geometric shapes. When rectangular slabs are spliced ​​together piece by piece along the arc, the slab joints inevitably exhibit a fan-shaped variation, narrowing on the inner side of the curve and widening on the outer side. The slab joint difference formula provided in this invention reveals the quantitative law of this geometric conflict through a concise mathematical relationship. The engineering approximation derivation of this formula is based on the geometric principle of the bisecting midpoint method: the prefabricated unit slab is considered as a chord on the centerline of the railway line, and the maximum distance between the chord and the arc is the midpoint. Since the plate is rectangular, the difference in the gap between the inner and outer sides of the curve can be approximately determined by the superposition effect of the distances at both ends, which is simplified to twice the distance on one side in engineering practice. Therefore, the difference in the gap, e, is directly proportional to the square of the plate length L and inversely proportional to the curve radius R.

[0043] The engineering value of this formula lies in directly mapping two design parameters (plate length L and radius R) to an operable plate joint difference value e. Using a standard plate length... For example, when hour, ;when hour, ;when hour, In actual construction, construction workers do not need to perform on-site calculations; they can directly determine the e-value by referring to a table based on the curve radius given in the design. This characteristic makes the determination of the joint difference in reproducible and consistent in construction. Different work teams and different sections can obtain a unified joint control standard by using the same formula or the same table, thus eliminating the dispersion of manual estimation from the source.

[0044] Based on the determined plate gap difference value e, this invention further provides the rules for determining the values ​​of the inner and outer plate gaps of the curve: inner plate gap Curved outer plate seam Where 'a' represents the design value of the slab gap at the centerline of the track (typically 20-30mm). The physical meaning of this rule is: using the track centerline as a reference, the slab gap difference 'e' is symmetrically distributed to both the inner and outer sides of the curve, with the inner side receiving half and the outer side receiving half. This symmetrical distribution strategy ensures that the slab centerline always remains consistent with the track centerline, avoiding overall slab offset caused by uneven slab gap distribution.

[0045] by , For example: Then the inner side panel seam outer panel seam This allows construction workers to precisely control the width of each joint, ensuring that the splicing of panels on curved sections meets both geometric fit requirements and maintains accurate centerline positioning.

[0046] The aforementioned method for determining the gap difference between slabs involves two levels of quantification: first, calculating the total difference *e*, and then allocating it to the inner and outer sides; this upgrades gap control from empirical estimation to formula-based calculation. Before laying each slab, construction workers can accurately calculate the inner and outer widths of the gap based on the current curve radius, and adjust the longitudinal position of the slab accordingly. This method ensures that the gap width remains continuously and gradually varied throughout the entire curve segment, avoiding deviations in the installation position of vibration isolators or defects in the pouring quality of wet joints between slabs caused by abrupt changes in the gap width.

[0047] Furthermore, according to one embodiment of the present invention, the following method is used to eliminate accumulated errors during the laying process of prefabricated unit panels: Four consecutive prefabricated unit panels are used as one error elimination unit; The first precast unit panel within the unit is positioned according to the theoretical panel joint. After the second precast unit slab is laid, the actual joint between the first and second precast unit slabs is measured, and the deviation between the actual joint and the theoretical joint is recorded as follows: ; When laying the third precast unit slab, the gap between it and the second precast unit slab should be adjusted to the theoretical value minus [the value is missing from the original text]. This ensures that the cumulative length from the first prefabricated unit panel to the third prefabricated unit panel matches the theoretical cumulative length. When laying the fourth precast unit panel, the gap between it and the third precast unit panel is adjusted to the theoretical value. At the same time, the total length from the first precast unit panel to the fourth precast unit panel is measured. If there is a remaining deviation between the total length and the theoretical total length, the remaining deviation is allocated to the gap between the third and fourth precast unit panels. The next unit starts from the 5th precast unit slab, repositions itself according to the theoretical slab seam, and repeats the above operation.

[0048] In this embodiment, the precast floating slabs are installed and finely adjusted piece by piece. The laying of each slab involves multiple sources of random deviation, including measurement errors, hoisting alignment errors, and jack adjustment errors. If each slab is positioned strictly according to the theoretical slab joint without cumulative error correction, the positioning deviation of the preceding slabs will be transmitted to the following slabs in the form of joint width errors, forming a vicious transmission chain of "the first slab is off → the second slab is also off → the third slab is even more off." When the length of the curved section reaches tens of meters, the cumulative error will cause the end slab to deviate significantly from the design position, and even irreversible quality defects such as misalignment of vibration isolator installation holes and excessive joint width.

[0049] This invention defines error elimination units, using four consecutive prefabricated unit plates as one error elimination unit, and sets error-zeroing sections between units. The first plate of each unit is repositioned according to the theoretical plate seam, meaning that the residual error of the previous unit will no longer be transmitted to the next unit. This mechanism cuts the originally infinitely extending error transmission chain into several independent closed loops of four plates each, thus blocking the cross-unit accumulation of errors at the system level.

[0050] Within the unit consisting of four boards, this invention designs a set of dynamic closed-loop control logic for detection, calculation, and compensation: The first step is to position the first board in the unit according to the theoretical board joint, which serves as the positioning reference for this unit; The second step involves laying the second board, measuring the actual gap between the first and second boards, and comparing it with the theoretical gap to determine the deviation value. This completes the quantitative detection of the first segment error; The third step involves laying the third board, adjusting the gap between it and the second board to the theoretical value minus [the value is missing from the original text]. This process brings the cumulative length of the first three plates back to the theoretical value. The mathematical essence of this operation is to cancel out the positive (or negative) error generated in the first section through the negative (or positive) adjustment of the seam in the second section, so that the cumulative error returns to zero at the midpoint of the unit. In the fourth step, when laying the fourth slab, the gap between it and the third slab is set according to the theoretical value, and the total length of the entire unit is measured. If there is a residual deviation, this residual deviation is allocated to the gap between the third and fourth slabs. This step serves as the final closed loop for eliminating unit errors, ensuring that the total length of the unit is strictly consistent with the theoretical total length.

[0051] The core of this algorithm lies in absorbing unavoidable random laying errors through slight elastic adjustments to the width of the joints. The designed joint width is typically 20-30mm, reserving space for wet joint pouring, and its width itself has a certain adjustable tolerance. This invention fully utilizes this tolerance space, eliminating errors within the joints without sacrificing the positioning accuracy of the panels themselves.

[0052] The present invention limits the error elimination unit to four consecutive boards, rather than two, three or more, and its technical rationale lies in: First, if the unit is too short (e.g., 2 boards), the error elimination frequency will be too high. Each unit can only correct the error within a very short distance, resulting in low construction efficiency and frequent adjustments to the board joints, which is not conducive to on-site operation. Second, if the unit is too long (e.g., more than 6 boards), the cumulative error at the end of the unit may have exceeded the adjustable tolerance range of the board seam, resulting in the remaining deviation not being completely absorbed and the error elimination failing. Third, the four boards correspond to a unit length of approximately 18m (based on a standard board length of 4.5m), achieving a balance between the cumulative error and the ability to adjust the board joints. In the measured data of the first test board or similar projects, the laying error of a single board is typically on the order of 1-3mm, the cumulative error of the four boards is approximately 4-8mm, while the board joint adjustment margin can reach more than 10mm, ensuring that the deviation in the total unit length can be completely absorbed.

[0053] It is worth noting that the traditional approach involves positioning each slab according to the theoretical joint spacing, and only making overall adjustments when a significant deviation in the position of the end slab is discovered. This often requires re-hoisting multiple slabs, resulting in substantial rework. The method of this invention reverses this passive situation to proactive adjustment: errors are detected, calculated, and eliminated within each unit, preventing them from accumulating to an uncontrollable level before being addressed. Construction personnel can monitor the cumulative error status in real time during the laying process and eliminate it through minor adjustments to the joint spacing. This method ensures that the final positioning accuracy of the entire slab depends only on the control quality within a single unit, and is independent of the total length of the curve segment, fundamentally solving the technical problem of cumulative errors diverging with increasing laying length.

[0054] Furthermore, according to one embodiment of the present invention, the lateral support is installed after the plate is finely adjusted and before the lifting process begins, so as to resist the slippage of the plate towards the inside of the curve during the lifting process.

[0055] In this embodiment, the construction of precast floating slabs involves two stages with drastically different mechanical requirements: the fine-tuning stage requires the slab to have the ability to move freely, allowing for millimeter-level lateral translation and minor angular corrections using jacks; the jacking stage requires the slab to maintain lateral stability during vertical lifting to prevent uncontrollable slippage due to horizontal forces. If the lateral supports are installed prematurely during the fine-tuning stage, the slab will be laterally constrained and unable to be repositioned, making the fine-tuning process impossible. If the lateral supports are installed after jacking has begun, slippage has already occurred in the initial stage of jacking, and the supports can only limit subsequent displacement but cannot correct the deviations already incurred.

[0056] This invention precisely sets the installation time after fine-tuning is completed and before the lifting process begins. Its technical advantage lies in inserting a clear mechanical state switching node between the two processes: before fine-tuning is completed, the plate is in a free state without lateral constraints, and the fine-tuning operation is unimpeded; after fine-tuning is completed and before lifting begins, the lateral supports are installed in place, restricting the lateral freedom of the plate and pre-setting constraint boundaries for the upcoming lifting dynamic disturbances. This timing arrangement ensures, from a process perspective, that the two conflicting requirements of fine-tuning accuracy and lifting stability are both met.

[0057] During the jacking process, hydraulic jacks apply vertical lifting forces at the four corners of the slab, causing the vibration isolators to compress and store elastic potential energy. Because the slab is placed on an extremely high, sloping base, the rebound force of the vibration isolators is perpendicular to the slab's plane. The projection of this force onto the horizontal plane points inwards along the curve, forming a horizontal component that drives the slab to slide inwards. Simultaneously, factors such as the friction between the slab and temporary pads, and the clearance between the vibration isolator sleeves and positioning pins, further weaken the slab's self-stabilizing ability.

[0058] The role of lateral bracing is to counteract the aforementioned horizontal force through passive compression. One end of the bracing is pressed against the side of the slab, while the other end is anchored to the tunnel wall or foundation, forming a horizontal reaction boundary pointing outwards from the curve. When the slab tends to slide inwards during the jacking process, the bracing is compressed, generating an elastic restoring force inside that is opposite to the direction of sliding. This transforms the horizontal movement tendency into the elastic strain energy of the bracing system, rather than the macroscopic displacement of the slab. This constraint mechanism ensures that the slab can only be lifted vertically during the jacking instant, and its lateral position is locked at the coordinates determined by fine-tuning, thus ensuring that the fine-tuning results are transmitted without distortion to the final stable state after the jacking is completed.

[0059] After the lateral supports are installed, the lateral displacement degree of freedom of the slab during the jacking process is directly constrained, and the tendency to slip is offset before it occurs. Thus, the jacking slip problem is transformed from a dynamic problem requiring precise prediction and compensation to a static problem that can be solved by setting constraint devices. This transformation significantly reduces the dependence on the accuracy of compensation estimation, making the construction control logic simpler and more reliable.

[0060] This invention involves installing lateral supports after fine-tuning and before lifting begins, ensuring that the slab is consistently subjected to horizontal constraints pointing outwards from the curve throughout the lifting process. The support density is determined based on the superelevation value; in sections where the superelevation exceeds a preset value, at least one support is installed for each slab to ensure sufficient constraint stiffness even under conditions of maximum horizontal force.

[0061] In this embodiment, the lateral support establishes a clear mechanical state transition node between the fine-tuning stage and the jacking stage. By precisely setting the critical timing of the process, the timing conflict between constraints and adjustments is avoided. In the jacking transient, a horizontal reaction force pointing to the outside of the curve is provided in a passive compression manner, which transforms the horizontal slippage trend into the elastic strain energy of the support system, ensuring that the fine-tuning results are completely maintained under jacking disturbances. The dynamic control problem of jacking slippage is transformed into a static constraint problem, which simplifies the construction control logic and solves the engineering problems of plate instability and plate joint squeezing during the jacking process.

[0062] Furthermore, according to one embodiment of the present invention, the method for reserving lifting operation space is as follows: a rigid square wooden board of a predetermined thickness is placed between the board and the base, so that the board is in a suspended state.

[0063] In this embodiment, by placing rigid square wooden boards of a predetermined thickness at certain intervals between the board and the substrate to suspend the board, the friction interface during the fine-tuning stage is transferred from the rough substrate to the controllable contact surface of the wooden boards, eliminating the interference of nonlinear frictional resistance on the fine-tuning accuracy. The predetermined thickness simultaneously meets the vertical stroke requirements of the jacking process and the stability requirements of the fine-tuning stage, achieving a precise match between the mechanical requirements of the two stages. The suspended state allows the board to freely release its initial stress, ensuring a zero-stress state before the vibration isolator is supported. Multiple functions are achieved simultaneously with a minimalist temporary padding process, significantly improving the overall construction efficiency and quality control level.

[0064] Furthermore, according to one embodiment of the present invention, when the method is applied to a circular tunnel or a rectangular tunnel, the calculation of the additional offset is based on the vertical distance from the corresponding track reference point to the upper and lower surfaces of the precast unit plate according to the tunnel cross-section form. The vertical distance between the corresponding circular tunnels is greater than the vertical distance between the corresponding rectangular tunnels.

[0065] In this embodiment, circular tunnels and rectangular tunnels differ fundamentally in their civil engineering structure: circular tunnels are constructed using the shield tunneling method, with the inner walls of the segments being arc-shaped. The track structure requires leveling on the arc-shaped base using a relatively thick track bed, resulting in a typically larger track structure height. Rectangular tunnels, on the other hand, are mostly constructed using the cut-and-cover method or mining method, with a flat bottom slab and a relatively thin track bed. This structural difference directly leads to a significant difference in the vertical distance from the track reference point to the surface of the precast unit slab in the two cross-sections; that is, this distance is larger in circular tunnels and smaller in rectangular tunnels.

[0066] The track reference point is a key input parameter for calculating the additional offset, and its vertical distance from the slab surface directly affects the calculation result. If the construction method does not differentiate between cross-sectional forms and uses a uniform parameter, in circular tunnels, the vertical distance value will be too small, resulting in insufficient calculation of the additional offset. The actual offset of the slab will be greater than the calculated value, causing positioning deviation. In rectangular tunnels, the value will be too large, resulting in over-calculation and similarly causing positioning inaccuracies.

[0067] This invention goes beyond simply providing calculation parameters for a single cross-section. Instead, it establishes a decision chain involving cross-sectional shape, vertical distance, and offset: before construction, the tunnel cross-section type is checked against the design drawings, and the corresponding vertical distance parameter is selected accordingly, then substituted into the additional offset calculation formula. This decision chain enables the calculation method to adapt to different scenarios. The same laying method can be accurately implemented in tunnels with different cross-sectional shapes simply by switching the corresponding vertical distance parameter, without needing to re-derive the formula or rely on trial and error on site.

[0068] The vertical distance for a circular tunnel is greater than that for a rectangular tunnel; this directional constraint ensures the correctness of parameter selection. Based on this constraint, and combined with the design value of the track structure height for a specific project, the accurate vertical distance value can be determined, allowing for precise calculation of additional offsets.

[0069] This invention establishes a correspondence between cross-sectional forms and calculation parameters, enabling the overall method to be applied not only to a single cross-sectional form but also accurately implemented in both circular and rectangular tunnel sections, the two main types of subway tunnels. This universality has significant engineering value: a subway line often includes multiple cross-sectional forms such as shield tunnel sections (circular tunnels), cut-and-cover stations and sections (rectangular tunnels). If the laying method is only applicable to a single cross-section, frequent switching of processes or reliance on experience for correction is required during construction, resulting in low efficiency and large quality fluctuations. This invention covers two typical cross-sections with a unified parameter selection rule. Construction personnel only need to update the vertical distance parameters at the cross-section transition points, while keeping the remaining procedures consistent, achieving standardized and continuous operation of the laying process throughout the entire line.

[0070] In this embodiment, the tunnel cross-section parameter adaptation reveals the objective differences in track structure height between circular and rectangular tunnels and their impact on the calculation of additional offset. It establishes a mapping relationship between cross-section form and vertical distance parameters, enabling the calculation method to have cross-section adaptive capability, expanding the engineering applicability of the method, and ensuring that the precast floating slab positioning and laying method in curved sections can be accurately implemented in both mainstream tunnel cross-sections, thus solving the defect of insufficient adaptation of measurement and control technology scenarios.

[0071] Furthermore, according to one embodiment of the present invention, the allowable range is that both longitudinal and lateral positioning errors are less than or equal to a threshold, and the threshold matches the specifications of the leveling shims of the vibration isolator after jacking.

[0072] In this embodiment, after the prefabricated floating slab is lifted, the vibration isolator enters its working state. At this time, the elevation and planar position of the slab can be fine-tuned by adding or removing leveling shims between the inner and outer cylinders of the vibration isolator. The leveling shims typically have standardized thickness specifications, with a single layer thickness of 1-2 mm. By combining shims of different thicknesses, elevation and planar position fine-tuning at the 1 mm level can be achieved. This adjustment capability constitutes the upper limit of the process for correcting the slab position after lifting.

[0073] This invention matches the longitudinal and transverse positioning error thresholds during the fine-tuning stage with the specifications of the leveling shims. The technical logic is as follows: if the initial positioning error after fine-tuning exceeds the threshold, the required position correction after jacking will exceed the adjustable range of the leveling shim assembly. At this point, the transverse adjustment capability of the vibration isolator is insufficient to compensate for the initial deviation, forcing construction personnel to take two remedial measures: depressurize and lower the slab, then re-fine-tune and reposition, forming a rework cycle of fine-tuning, jacking, exceeding tolerances, lowering, and further fine-tuning; or, replace the leveling shim assembly with a non-standard specification, increasing the complexity of the process and the difficulty of material management.

[0074] After matching the threshold with the shim specifications, the fine-tuning stage can ensure that the initial positioning error falls within the range that the shim adjustment capability can cover after jacking. Taking the 5mm threshold determined in engineering practice as an example, the remaining deviation of the planar position after jacking can be corrected within the lateral adjustment stroke of the vibration isolator by the shim combination, without the need for secondary hoisting or major rework.

[0075] This invention decomposes the achievement of the final geometric accuracy of the track into two stages by setting a threshold that matches the adjustment capabilities of subsequent processes: the fine-tuning stage is responsible for positioning the plate to an initial accuracy within the threshold range; the shim adjustment stage after lifting is responsible for completing the final fine-tuning based on the initial accuracy. The technical advantage of this decomposition is that it clarifies the accuracy responsibility boundaries of each process. The fine-tuning process no longer pursues an unattainable absolute zero error, but uses the threshold as the pass / fail criterion; once the threshold is met, it can proceed to the next process. The shim adjustment stage after lifting completes the convergence of residual deviations within its designed adjustment capability range. The two processes each perform their respective duties and are interconnected, avoiding over-fine-tuning or under-tuning due to unclear responsibilities.

[0076] Without clearly defined thresholds, the stopping criteria during the fine-tuning phase often rely on the operator's experience and judgment. This subjective judgment leads to inconsistent fine-tuning quality across different work groups and sections. This invention uses a threshold matching the gasket specifications as an objective criterion, transforming the decision to stop fine-tuning from subjective experience into objective measurement. Construction personnel only need to check whether the longitudinal and transverse errors are less than or equal to the threshold; if the standard is met, the process stops; otherwise, adjustments are made. This quantitative standard ensures a high degree of consistency in fine-tuning quality across all work areas, eliminating fluctuations in construction quality caused by differences in personnel experience.

[0077] This invention controls the initial error within a threshold, allowing elevation and level adjustments after jacking to be completed using only standard-specification shims, eliminating the need for additional non-standard shims or complex shim selection calculations. This significantly simplifies the post-jacking adjustment process, reducing the skill requirements and workload for construction workers.

[0078] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0079] It should be understood that the sequence number of each step in the invention and its embodiments does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A method for positioning and laying precast floating slabs in curved sections, characterized in that, Includes the following steps: S1. Establish the line benchmark, and set up the line centerline control stakes based on the CPⅢ control points. Set up one control stake at a preset distance in the curved section and set up the five major stake points of the curve. Set up the center control stake of the slab joint and the projected edge line of the precast unit slab according to the length of the precast unit slab. The slab joint in the curved section is fan-shaped. The slab joint at the line centerline is the design value. The difference between the slab joint on the inner side and the outer side of the curve is determined by the line radius and the slab length. S2. Calculate the theoretical offset. The theoretical offset between the centerline of the precast unit slab and the centerline of the track is determined using the bisecting mid-vector method. This theoretical offset is half of the total vector of the curve. Based on this, the additional offset caused by superelevation is superimposed. The additional offset is determined by the product of the vertical distance from the track reference point to the surface of the precast unit slab and the superelevation according to a proportional coefficient. The additional offset of the upper surface of the precast unit slab is less than that of its lower surface, and both are offsets in the same direction outward from the track. At the same time, the compensation amount for the inward sliding of the precast unit slab caused by the lifting process of lifting the precast unit slab is included to obtain the comprehensive offset. S3. Theoretical positioning: Starting from the track reference point, determine the theoretical center position of the prefabricated unit plate along the direction of the comprehensive offset; hoist the prefabricated unit plate above the base, so that the center line of the plate coincides with the theoretical center position, the outline of the plate coincides with the projected edge line, and reserve lifting operation space between the plate and the base. S4. Fine-tuning positioning: With the plate not lifted, use auxiliary measuring tools to measure the lateral position deviation of the plate; based on the difference between the measured deviation and the theoretical offset, use jacks to adjust the position of the plate until the deviation between the measured position and the theoretical position is controlled within the allowable range. S5. Maintain stability. After the slab is adjusted to the correct position on curved sections, install lateral supports. For sections with a superelevation greater than the preset value, install at least one support for each slab to resist the tendency of the slab to slip along the curve during the lifting process.

2. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, The method for calculating the additional offset includes: Additional offset on the upper surface of the prefabricated unit panel: ; Additional offset on the lower surface of the prefabricated unit panel: ; In the formula, This is the vertical distance from the track reference point to the surface of the precast unit plate; This is the vertical distance from the track reference point to the lower surface of the precast unit slab; This refers to the orbital superelevation value. For track gauge; The upper surface has an additional offset. Less than the additional offset of the lower surface Both are deflected outwards from the track.

3. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, The compensation amount is the allowance for the plate to slide inward during the lifting process.

4. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, The method for determining the plate gap difference is as follows: The curved section of the line is an arc, and the prefabricated unit panels are rectangular. When the rectangular panels are spliced ​​along the arc, the panel seam forms a fan shape with a smaller inner part and a larger outer part. The precast unit slab is considered as a chord on the centerline of the curved section of the railway line, and the maximum distance between the chord and the arc formed by the curved section of the railway line is the moment of inflection. Since the precast unit slabs are rectangular, the slab gap difference 'e' generated on the inner and outer sides of the line in curved sections is considered to be determined by the superposition effect of the two-end distances, i.e., twice the single-sided distance 'F'. Therefore, the slab gap difference 'e' is calculated using the following formula: ； In the formula: L is the length of the prefabricated unit panel, and R is the radius of the curved section; The inner side plate seam of the curve The outer side plate seam of the curve , where a is the design value of the plate joint at the center line of the line.

5. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, The following methods are used to eliminate accumulated errors during the installation of precast unit panels: Four consecutive prefabricated unit panels are used as one error elimination unit; The first precast unit panel within the unit is positioned according to the theoretical panel joint. After the second precast unit slab is laid, the actual joint between the first and second precast unit slabs is measured, and the deviation between the actual joint and the theoretical joint is recorded as follows: ; When laying the third precast unit slab, the gap between it and the second precast unit slab should be adjusted to the theoretical value minus [the value is missing from the original text]. This ensures that the cumulative length from the first prefabricated unit panel to the third prefabricated unit panel matches the theoretical cumulative length. When laying the fourth precast unit panel, the gap between it and the third precast unit panel is adjusted to the theoretical value. At the same time, the total length from the first precast unit panel to the fourth precast unit panel is measured. If there is a remaining deviation between the total length and the theoretical total length, the remaining deviation is allocated to the gap between the third and fourth precast unit panels. The next unit starts from the 5th precast unit slab, repositions itself according to the theoretical slab seam, and repeats the above operation.

6. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, The lateral support is installed after the plate is finely adjusted and before the lifting process begins, to resist the slippage of the plate towards the inside of the curve during the lifting process.

7. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, The method for reserving the lifting operation space is as follows: a rigid square wooden board of a preset thickness is placed between the board and the base, so that the board is in a suspended state.

8. The method for positioning and laying precast floating slabs in curved sections according to claim 1, characterized in that, When the method is applied to a circular tunnel or a rectangular tunnel, the calculation of the additional offset is based on the vertical distance from the corresponding track reference point to the upper and lower surfaces of the precast unit plate, selected according to the tunnel cross-section form. The vertical distance between the corresponding circular tunnels is greater than the vertical distance between the corresponding rectangular tunnels.

9. The method for positioning and laying precast floating slabs in curved sections according to any one of claims 1-8, characterized in that, The allowable range is that the longitudinal and lateral positioning errors are both less than or equal to the threshold, and the threshold is matched with the specifications of the leveling shims of the vibration isolator after jacking.

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