Mountainous region electric transportation track laying method

Abstract

The invention belongs to the technical field of rail traffic engineering and mountainous region transportation equipment installation, and relates to a construction method of a mountainous region electric transportation rail laying method. The method solves the technical problems that in traditional mountain track laying, disturbance to a mountain is large, a supporting structure and the geological environment are not coordinated, and geological disasters are likely to be induced. Comprising the following steps: constructing a four-dimensional high-fidelity geological information model along a track through multi-source sensor fusion; designing a non-uniformly distributed self-adaptive anchoring point array by adopting finite element analysis and topological optimization based on the model; performing minimally invasive drilling and two-stage pressure grouting by using an automatic drilling and grouting integrated platform to form a distributed micro pile anchoring unit; the gridding connecting tie bars and the adjustable track supporting bases are assembled to form an integral bearing structure; and a long-term health monitoring system is integrated.

Description

Technical Field

[0001] This invention belongs to the technical field of rail transit engineering and mountain transportation equipment installation, specifically, it relates to a method for laying mountain electric rail tracks. Background Technology

[0002] Mountain rail transit, as a highly efficient and environmentally friendly modern transportation system, plays an increasingly important role in mineral resource development, passenger transport in tourist areas, transportation of large engineering materials, and timber collection and transportation in forest areas. Compared with traditional road transportation, rail transit systems offer a crucial solution for mountain transportation under complex geological conditions due to their significant advantages, such as large carrying capacity, low energy consumption, strong adaptability to terrain, and relatively small impact on the ecological environment.

[0003] In existing technological practices, the common approach for laying mountain electric rail tracks is a segmented construction method based on discrete load-bearing foundations. The core logic of this method lies in first selecting a series of key load-bearing points along the predetermined track route through geological surveys and engineering measurements. Then, independent, localized foundation construction is carried out at these points, typically involving excavation of the mountain, pouring of reinforced concrete piers, or construction of foundations. After these load-bearing foundations, serving as independent support units, reach their predetermined strength, prefabricated standardized track segments are placed on the piers using hoisting or other methods, and then connected and adjusted segment by segment to ultimately form a complete track line. This method decomposes the complex problem of continuous track laying into a series of relatively independent "pier-beam erection" work units. Technically, it offers a clear path, is easy to standardize and manage, and can adapt to varying terrain to a certain extent. Under specific historical periods and technological conditions, it effectively solved the fundamental construction problem of building mountain rail tracks from scratch.

[0004] While existing laying methods address the immediate issue of track structure support, they inadvertently create a more complex and hidden deep-seated technical contradiction regarding the long-term stability of the track-mountain system. The core of this contradiction lies in the inherent conflict between the localized, invasive construction methods and the holistic and systematic requirements of the mountain environment. Therefore, how to transcend the limitations of traditional "point support" thinking and innovate a method for laying mountain electric rails that integrates the track-bearing structure with the mountain's geological environment, minimizing disturbance to the original mountain structure during construction while meeting track stiffness and precision requirements, thus achieving a coordinated and stable engineering structure and natural environment, has become a key challenge and an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for laying mountain electric rail tracks. This method aims to surpass the traditional construction paradigm of discrete load-bearing foundations. By constructing a distributed, gridded load-bearing system that is deeply integrated with the shallow geological structure of the mountain, it achieves high-precision and high-stability track laying while minimizing disturbance to the original mountain environment and actively improving the geological stability along the track. This fundamentally solves the technical contradiction between track structure support and the integrity of the mountain environment.

[0006] To achieve the aforementioned objectives, this invention provides a method for laying mountain electric rail tracks. Its core technical solution lies in abandoning the traditional construction logic of deep excavation and pouring of independent piers, and instead employing an adaptive, minimally invasive, sequential integrated anchoring grid construction technology based on a high-fidelity geological model. This method first establishes a four-dimensional high-precision geological information model of the mountain along the track through multi-source sensor fusion detection. Second, based on this model, a non-uniformly distributed anchoring point array layout scheme, precisely matched to local geomechanical properties, is generated through finite element analysis and topology optimization algorithms. Subsequently, an automated, lightweight construction platform is used to perform minimally invasive drilling and pressure grouting according to this scheme, constructing a series of interconnected micro-pillar anchoring units in the shallow surface layer of the mountain. Finally, prefabricated gridded connecting rods and track support bases are installed on these anchoring units, forming an integral load-bearing structure system that uniformly distributes the track load to a large area of ​​shallow soil and rock, while simultaneously reinforcing the slope.

[0007] Specifically, the method for laying mountain electric rail tracks provided by the present invention includes the following steps:

[0008] The first step is the construction of a high-fidelity four-dimensional geological information model along the railway line. This step aims to acquire precise three-dimensional geometric information of the mountains beneath and around the railway line, as well as information on their internal geological structure, soil and rock mechanical parameters, and hydrological conditions, forming a four-dimensional dataset containing spatial geometric coordinates (X, Y, Z) and geological attributes (P). This step is accomplished using an integrated, self-propelled geological survey data acquisition system. This system comprises a high-precision Global Navigation Satellite System (GNSS) receiver, a fiber optic gyroscope inertial measurement unit (IMU), a ground-penetrating radar (GPR) array, and a central data fusion and processing unit.

[0009] The GNSS receiver is a dual-frequency receiver supporting real-time kinematic (RTK) differential technology, with a three-dimensional spatial positioning accuracy set to be better than 2 centimeters. The IMU is used to capture the attitude angles (roll, pitch, and yaw) of the acquisition system in real time, with a static angle measurement accuracy set to be better than 0.01 degrees and a dynamic accuracy better than 0.05 degrees, and a data update frequency of 200 Hz. The GNSS and IMU data are tightly coupled using a Kalman filter algorithm, providing centimeter-level spatial position and attitude information for each detection data point of the ground-penetrating radar array.

[0010] The ground-penetrating radar array employs a stepped-frequency continuous wave (SFCW) system, consisting of one transmitting antenna and eight receiving antennas. Its central operating frequency is set at 400 MHz, with an effective detection depth ranging from 0.5 meters to 15 meters and a vertical resolution of 5 centimeters. During data acquisition, the ground-penetrating radar array continuously transmits electromagnetic waves along a predetermined track centerline and receives reflected signals. The central unit for data fusion and processing incorporates a dedicated algorithm. This algorithm, based on the two-way travel time, amplitude attenuation, and phase change information of electromagnetic waves, inversely determines the dielectric constant distribution of the subsurface medium. Furthermore, based on a pre-defined empirical relationship model between the dielectric constant of soil and rock and physical and mechanical parameters (such as density, water content, compactness, and fracture development), the algorithm transforms the dielectric constant distribution map into a detailed and visualized three-dimensional geological structure profile of the subsurface.

[0011] By registering and fusing high-precision 3D topographic data acquired by the GNSS-IMU system with 3D geological structure data acquired by the GPR system, a high-fidelity 4D geological information model is generated. This model not only accurately depicts the undulating morphology of the mountain surface but also reveals key geological information such as soil layer boundaries, bedrock depth, fault and fracture zone distribution, location of weak interlayers, and groundwater-rich areas within a specific depth range below the surface. This provides a unique and deterministic data foundation for subsequent anchoring grid design.

[0012] The second step involves the optimization design of the adaptive anchoring mesh layout. This step aims to use the aforementioned four-dimensional geological information model as input and numerical simulation technology to design an optimized construction blueprint for the geological engineering sequential integrated anchoring mesh. This blueprint precisely defines the spatial coordinates, drilling angle, drilling depth, grouting pressure, and grouting volume of each anchoring unit. The optimization design process is executed on a dedicated engineering computing workstation running software that integrates a finite element analysis (FEA) module and a topology optimization algorithm.

[0013] In this step, firstly, the four-dimensional geological information model is imported into finite element analysis software to establish a refined three-dimensional solid model that accurately reflects the geological conditions along the track. In the model, the material properties (elastic modulus, Poisson's ratio, cohesion, and internal friction angle) of different soil and rock masses are assigned values ​​based on the geological properties (P) in the four-dimensional model. Secondly, preset track loads are applied to the model. These loads include the track structure's self-weight, train dynamic loads, and environmental loads such as wind, snow, and earthquakes. The loads are applied as moving line loads distributed along the track line.

[0014] Subsequently, a topology optimization algorithm was initiated. The objective function of this algorithm was set to minimize the overall material usage of the anchoring grid system, provided that the deformation (settlement, torsion) of the track structure is less than the design specification limits and the stress levels within the grid structure system and the soil mass are both below their respective material strength safety thresholds. The algorithm's constraints included the minimum spacing of anchoring units, the maximum drilling depth, and avoidance of specific geologically vulnerable areas (such as fault fracture zones). The algorithm's iterative process continuously adjusts the material distribution throughout the design domain, automatically identifying the optimal force transmission path, ultimately generating a non-uniform, well-spaced array of anchoring points. In areas with excellent geological conditions and intact rock masses, the anchoring point spacing is larger; while in areas with poor geological conditions and weak interlayers, the anchoring points are automatically densified, and their depth and angle are optimized to penetrate the weak layers and anchor in the stable bedrock below.

[0015] The final output of the optimized design is a digital construction instruction set containing a unique ID for each anchoring unit, three-dimensional coordinates (x, y, z), borehole azimuth angle, borehole inclination angle, design borehole depth, and pressure-time curves and grouting volume parameters for staged grouting. This instruction set will serve as the direct input for the next step of automated construction.

[0016] The third step involves the sequential construction of minimally invasive automated anchoring units. This step utilizes a multi-functional, tracked, electrically driven automated drilling and grouting integrated platform to precisely construct each anchoring unit on-site, based on the digital construction instruction set generated in the second step.

[0017] The core components of the automated drilling and grouting integrated platform include: a tracked chassis with autonomous navigation and precise positioning capabilities; a six-axis articulated robotic arm with an integrated high-frequency hydraulic rotary impact drill bit as its end effector; a vehicle-mounted dual-tank automatic grouting system; a high-pressure plunger-type grouting pump; and a central controller equipped with a real-time motion control (RMC) system.

[0018] During construction, the platform autonomously navigates to the first anchoring point using its own GNSS-RTK receiver and IMU, based on the target coordinates set in the digital construction instruction set. Its positioning error is controlled within 3 centimeters. Upon arrival, the platform's hydraulic outriggers automatically level and lock. Subsequently, the central controller drives the six-axis robotic arm to precisely adjust the drill bit's spatial attitude, ensuring its axis perfectly aligns with the drilling azimuth and inclination angles set in the instruction set, with an angle adjustment accuracy of 0.1 degrees.

[0019] The drilling process employs a micro-disturbance drilling technique. The drill bit is a 90mm diameter casing drill bit. Simultaneously, a high-strength hollow seamless steel pipe (the micro-pile body) with an outer diameter of 73mm, a wall thickness of 8mm, and a yield strength of not less than 550 MPa is inserted into the hole. High-pressure air is used for slag removal during drilling to prevent mud contamination of the borehole wall. The drilling depth is monitored in real-time by the encoder of the robotic arm, and drilling automatically stops when the designed depth is reached.

[0020] After drilling is completed, the pressure grouting stage begins. The grouting process is designed as a two-stage grouting procedure. The first stage is consolidation grouting, where an onboard automatic grout mixing system prepares 42.5R grade silicate cement grout with a water-cement ratio of 0.5. This grout is injected into the bottom of the hole through the grouting hole at the bottom of the hollow pile body at a relatively low pressure of 0.5 to 1.0 MPa, filling the annular gap between the pile body and the hole wall from bottom to top. The grouting volume in this stage is precisely measured by a flow meter and stops when the preset value is reached. The second stage is splitting expansion grouting. After the initial setting of the grout in the first stage, the grout mixing system prepares a special cement grout with a water-cement ratio of 0.45, and contains 0.5% by weight of polycarboxylate superplasticizer and 3% by weight of micro-expansion agent. The grouting pump, operating at a high pressure of 2.5 to 4.0 MPa, injects grout through a pre-embedded grouting pipe into the pile body. This process splits, compacts, and permeates the soil and rock mass at a specific depth around the pile, forming an enlarged head and several grout veins penetrating deep into the soil and rock fissures. This creates a composite anchor body that is interlocked and tightly bonded to the surrounding soil and rock mass. The pressure and flow rate during the grouting process are monitored throughout by sensors and compared in real time with design parameters to ensure effective grouting.

[0021] Following the digital construction instruction set, the platform sequentially completes the construction of all anchoring units, thereby forming an "artificial root system" deeply embedded in the ground, composed of numerous composite anchoring bodies, on the shallow surface of the mountain.

[0022] The fourth step is the assembly of the grid-connected tie rods and the track support base. After the cement grout of all anchoring units has reached its design strength, the load-bearing structure above ground is installed.

[0023] First, a prefabricated steel anchor head connector is installed on the exposed portion of the top of each micropile. This connector is connected to the pile body via high-strength threads. Then, using lightweight hoisting equipment, the prefabricated longitudinal connecting beams and transverse connecting rods are hoisted into place. The longitudinal connecting beams are H-beams, their specifications determined according to the design load, made of Q355B high-strength low-alloy structural steel, and hot-dip galvanized for corrosion protection. The longitudinal connecting beams are placed on top of the same row of anchor head connectors. The transverse connecting rods are circular steel pipes used to connect adjacent rows of longitudinal connecting beams to enhance the lateral stiffness and integrity of the entire grid. All connections between the longitudinal connecting beams, transverse connecting rods, and anchor head connectors are made using M24, 10.9 grade torsion-shear type high-strength bolts, ensuring the rigidity and reliability of the connections. Through this step, a complete, horizontal, spatially gridded steel structure load-bearing platform is constructed.

[0024] Finally, a track support base is installed at a predetermined position on the upper flange of the longitudinal connecting beam. This track support base is a modular component with three-dimensional precision adjustment capabilities. Its structure consists of a base plate, a spherical adjusting seat, a trapezoidal threaded lifting sleeve, and a top fixed saddle. The base plate is bolted to the longitudinal connecting beam. By rotating the lifting sleeve, millimeter-level adjustments to the vertical position of the track support point can be achieved; by adjusting the spherical adjusting seat, precise setting of the track's lateral slope (superelevation) can be achieved.

[0025] The fifth step involves the integration of track laying with the long-term system status monitoring network. After all track support bases are installed and initially adjusted, the standard track sections are laid, connected, and final fine-tuned. Using a total station or laser collimator as the measurement benchmark, the geometric state of the track (gauge, level, elevation, and orientation) at each point is precisely measured. Through fine-tuning of the track support bases, the final accuracy of the track line fully meets the design requirements.

[0026] As a further embodiment of the invention, a long-term health monitoring system is integrated during the construction of the anchoring grid. This system consists of embedded sensors, a data acquisition unit, and a wireless transmission module. Distributed fiber optic grating (FBG) strain sensors are attached or welded to key micropiles and longitudinal connecting beams to monitor stress distribution and changes in the structure during operation. Pore water pressure gauges and microelectromechanical systems (MEMS) accelerometers are embedded in the soil and rock around specific anchoring points to monitor the internal hydrological conditions and minute vibrations of the slope. Data from all sensors is collected by the data acquisition unit and periodically transmitted to a remote monitoring center via a wireless network based on low-power wide-area Internet of Things (LoRaWAN) technology. This monitoring system provides objective data for the full lifecycle safety assessment and predictive maintenance of the track system.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. By using a serialized integrated anchoring grid from geological engineering to replace the discrete load-bearing base, the load is distributed in a large area of ​​shallow rock and soil, avoiding large-scale concentrated excavation for the construction of a single foundation. The disturbance to the original structure and vegetation of the mountain during construction is minimized, thus protecting the integrity of the ecological environment.

[0029] 2. The two-stage pressure grouting process in the method is not only used to anchor micropiles, but also to compact and reinforce the soil and rock around the anchoring point, which actively improves the overall stability of the slope along the track and realizes the integration of track support and slope protection, fundamentally eliminating the risk of geological disasters induced by construction.

[0030] 3. The adaptive anchoring point layout optimization based on a high-fidelity four-dimensional geological model enables the parameters of each anchoring unit to be precisely designed for local geological conditions, achieving the best match between structural bearing capacity and geological conditions. This avoids material waste or insufficient safety redundancy caused by the "one-size-fits-all" design in traditional methods, and improves resource utilization efficiency and long-term system safety.

[0031] 4. The digital design and automation of the entire process, along with minimally invasive construction, eliminates the reliance on large heavy machinery, greatly improves construction accuracy and project quality, reduces the intensity and safety risks of manual labor in complex mountainous environments, and shortens the construction cycle.

[0032] 5. The constructed grid-based load-bearing system has good integrity and redundancy. Even if a single anchor point fails, the load can be quickly redistributed through the grid, ensuring the robustness of the system. The integrated long-term health monitoring system transforms the operation and maintenance of the track system from passive repair to proactive early warning and maintenance, ensuring long-term operational safety. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the mountain electric rail track laying method of the present invention.

[0034] Figure 2 This is a schematic diagram of the overall structure of the track-bearing structure system after the completion of the track laying of this invention on the mountain.

[0035] Figure 3 This is a schematic cross-sectional view of a single composite anchor body in this invention.

[0036] Figure 4 This is a schematic diagram of the track support base in this invention.

[0037] The attached figures are named as follows: 1. Miniature pile body; 2. Composite anchor body; 3. Anchor head connector; 4. Longitudinal connecting beam; 5. Transverse connecting tie rod; 6. Track support base; 7. Track row; 8. Base plate; 9. Spherical adjustment seat; 10. Trapezoidal threaded lifting sleeve; 11. Top fixed saddle; 12. Enlarged head; 13. Grout vein. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the following will provide a more detailed description of a mountain electric rail track laying method provided by this invention, in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit its scope of protection. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0039] Reference Figures 1 to 4 This invention discloses a method for laying electric rail tracks in mountainous areas. The core of this method lies in constructing a distributed, grid-based, integrated load-bearing structure system deeply integrated with the shallow geological structure of the mountain, replacing the traditional discrete, large-scale excavation of independent load-bearing foundations. Through a series of highly integrated, digitalized, and automated engineering sequences, this method achieves minimally invasive and adaptive track laying in complex mountainous environments, ensuring high precision, high stability, and long-term operational safety of the track system.

[0040] In one specific embodiment, the laying method of the present invention is applied to the construction of a mountain electric rail line located in a subtropical humid climate zone with a slope of 25 to 40 degrees and lithology mainly composed of moderately weathered granite. The specific implementation process of the method includes the following interconnected steps.

[0041] The first step is to construct a high-fidelity four-dimensional geological information model along the track. The goal of this step is to acquire precise geological information within a 20-meter radius on either side of the track centerline, extending to a depth of 15 meters below the surface. This provides a unique and deterministic data foundation for subsequent anchoring grid optimization design. This step is accomplished using an integrated, tracked, self-propelled geological survey data acquisition system. This system autonomously travels at a constant speed of 0.5 meters per second along the pre-set track centerline and multiple parallel survey lines spaced 2 meters apart.

[0042] The core components of the geological survey data acquisition system include a Trimble R12i GNSS receiver, which supports all current satellite systems and enables RTK differential service. By receiving differential correction signals from ground base stations, it achieves real-time calculation of the three-dimensional spatial coordinates of the survey points, with a planar accuracy better than 8 mm and an elevation accuracy better than 15 mm. Rigidly connected to the GNSS receiver is an Xsens MTi-670 fiber optic gyroscope inertial measurement unit (IMU), which outputs the three-dimensional attitude angles (roll, pitch, and yaw) of the acquisition system at a frequency of 200 Hz. Its static angle measurement accuracy is 0.01 degrees, and its dynamic accuracy is 0.05 degrees. The GNSS position data and the IMU attitude data are fed into a central data fusion and processing unit. This unit runs an extended Kalman filter (EKF) algorithm to perform tightly coupled calculations on the two data points, providing each data sample from the ground-penetrating radar array with a high-precision timestamp, centimeter-level three-dimensional spatial coordinate and attitude label.

[0043] The system is equipped with a ground-penetrating radar (GPR) of the Swiss company Screening Eagle, specifically the Proceq GP8000 model. It employs a stepped-frequency continuous wave (SFCW) system, operating in the range of 200 MHz to 800 MHz, with a center frequency set at 400 MHz to balance detection depth and resolution. The radar consists of one transmitting antenna and eight linearly arranged receiving antennas, with an antenna array width of 0.8 meters. During its movement, the radar acquires data every 5 centimeters along the survey line, forming a high-density two-dimensional detection profile. The central data fusion and processing unit incorporates an electromagnetic wave propagation forward model based on the FDTD (Finite-Difference Time-Domain) method and a reverse-time algorithm based on full-waveform inversion. This algorithm first constructs an image of the subsurface reflection interface based on the two-way travel time information of the received signal. Then, by analyzing the amplitude attenuation rate and phase distortion of electromagnetic waves propagating in the medium, it inverts the dielectric constant distribution of the subsurface medium. Furthermore, this unit incorporates a localized database linking soil dielectric constants to physical and mechanical parameters. This database was established based on laboratory tests of soil and rock core samples taken from the project site. It precisely defines the nonlinear mapping relationship between the dielectric constant and key mechanical parameters such as elastic modulus, cohesion, and internal friction angle of weathered granite, residual soil, and completely weathered layers with different saturation and density. By calling this database, the system converts the inverted three-dimensional dielectric constant volume data into a refined three-dimensional geological structure model in real time. This model uses 10 cm x 10 cm x 5 cm voxels as the basic unit, and each voxel is assigned specific geological properties and mechanical parameters.

[0044] Finally, by precisely registering and seamlessly integrating the high-precision 3D terrain model with a point cloud density of 400 points per square meter acquired by the GNSS-IMU system and the underground 3D geological structure model acquired by the GPR system in a unified coordinate system, a high-fidelity 4D geological information model covering the entire construction area was generated. This model not only depicts the real landforms of the mountain with centimeter-level precision, but also clearly reveals the following layers: a 0.5-meter-thick humus layer, 0.5 to 6-meter-thick layers of completely and strongly weathered rock, a moderately weathered bedrock surface below 6 meters, and several densely jointed fracture zones ranging from 0.3 to 1.2 meters in width, as well as two groundwater-rich areas. This 4D model provides a digital twin of the physical world for the second-step optimization design.

[0045] The second step involves the optimization design of the adaptive anchoring mesh layout. This step is completed on an engineering workstation equipped with dual Intel Xeon Platinum 8380H processors and 512GB of memory, running ANSYS Mechanical finite element analysis software and its built-in topology optimization module. First, the high-fidelity four-dimensional geological information model generated in the previous step is imported into ANSYS software. Using a custom material library, the geomechanical parameters of each voxel are precisely assigned to the model, establishing a three-dimensional solid finite element model containing tens of millions of elements that highly matches the actual geological conditions.

[0046] Secondly, track design loads were applied to the model. The track structure's self-weight was calculated at 250 kg per meter and applied to the track as a uniformly distributed line load. The train dynamic load was converted into an equivalent static load using the impact coefficient method based on the axle load and operating speed of the design vehicle (an 8-ton electric transport vehicle). The most unfavorable loading condition, namely the load combination when two trains intersect on a curve, was considered and simulated in the model as a moving concentrated force. In addition, based on local meteorological and seismic data, a 50-year return period basic wind pressure (0.45 kN / m²) and horizontal seismic forces under intensity VII were superimposed.

[0047] Subsequently, a topology optimization algorithm based on the Variable Density Method (SIMP) was initiated. The design domain of the algorithm was set as a 100-meter-long, 10-meter-wide, and 12-meter-deep space of rock and soil beneath the track. The objective function of the algorithm was set to minimize the total volume of steel and cement grout used in the anchoring grid system under a series of constraints. The core constraints included: the maximum vertical settlement of the track under any load combination should not exceed 5 mm; the track torsion angle should not exceed 1 / 1000; the Mises equivalent stress of all anchoring units (micropiles) should not exceed 70% of their material yield strength, i.e., 385 MPa; the shear stress on the contact surface between the anchor body and the rock and soil should not exceed the shear strength of the rock and soil; the maximum principal stress inside the rock and soil must be less than its compressive strength; the minimum center-to-center spacing of the anchoring units was set to 1.5 meters to avoid mutual interference and stress superposition effects during construction; the maximum drilling depth was limited to 12 meters; and the algorithm was required to avoid fracture zones wider than 1 meter detected by GPR.

[0048] The optimization algorithm, through thousands of iterations, automatically adds and removes materials within the design domain, simulating the stress transmission path in the soil and rock mass. The calculation results clearly show that in sections with favorable geological conditions and shallow (less than 5 meters) weathered bedrock, the optimal force transmission path exhibits a sparse distribution, with anchor point spacing optimized to 4-5 meters, requiring only a 1.5-meter penetration through the weathered layer into the stable bedrock. In sections with poor geological conditions, weak interlayers, or areas rich in groundwater, the algorithm automatically densifies the anchor point arrangement, reducing the spacing to 2-2.5 meters, and precisely adjusting the drilling angle and depth to bypass or penetrate weak areas, reliably transferring the load to deeper, stable rock layers.

[0049] The final result of the optimized design is a digital construction instruction set, stored in XML format, containing all construction parameters for a total of 88 anchoring units deployed along a 100-meter test section. Each anchoring unit has a unique ID and details its three-dimensional spatial coordinates (x, y, z) in the project coordinate system, borehole azimuth (relative to true north), borehole inclination (relative to the horizontal plane), design borehole depth (accurate to 0.1 meters), as well as the grout mix ratio, target grouting pressure-time curve, and estimated grouting volume for each stage of the two-stage grouting process. This instruction set serves as a precise blueprint for subsequent automated construction.

[0050] The third step involves the sequential construction of minimally invasive automated anchoring units. The construction site utilizes an XE35U-E electric-driven multi-functional drilling and grouting integrated platform, custom-developed by XCMG (China's largest machinery manufacturer). Based on a 3.5-ton tracked excavator chassis, the platform is powered by a large-capacity lithium iron phosphate battery pack, achieving zero emissions and low noise operation. Its core operating device is a KUKA KR 120 R3200 PA six-axis industrial robot, with an integrated drilling tool at the end of its robotic arm, incorporating a high-frequency hydraulic rotary impact drill bit and a casing system. The platform also carries a dual-tank automatic grout mixing system, capable of precisely mixing cement grout with different water-cement ratios according to instructions, and a high-pressure plunger-type grouting pump with a maximum pressure of 8 MPa. The platform's central controller is equipped with a self-developed real-time motion control (RMC) system.

[0051] During construction, the platform first uses its integrated GNSS-RTK receiver (the same model as the survey system) and IMU to read the target coordinates of the first anchoring unit in the construction instruction set, and then autonomously navigates to the construction point. Its final positioning error is precisely controlled within 2 centimeters using laser target-assisted fine-tuning. Upon arrival, the four hydraulic outriggers automatically extend and adjust according to the terrain, accurately leveling and securely locking the platform. Subsequently, the central controller drives the six-axis robotic arm to perform precise attitude adjustments based on the drilling azimuth and inclination angles set in the instruction set, with the deviation of the drill bit's axis from the design parameters controlled within 0.1 degrees.

[0052] The drilling process employs a micro-disturbance casing drilling technique. The drill bit is a 90mm diameter eccentric casing drill bit manufactured by Sandvik. Simultaneously, as the drill bit rotates and impacts the rock and soil, a 73mm outer diameter, 8mm wall thickness seamless steel pipe (S550 grade high-strength geological drilling material manufactured by Baosteel Group) is inserted into the borehole as the pile body (i.e., miniature pile body 1 in the attached diagram). During drilling, a separate air compressor provides high-pressure air, which blows drill cuttings out of the annulus between the drill pipe and the borehole wall through the center hole of the drill pipe. This dry cuttings removal method avoids the pollution of the mountain's soil and water environment caused by traditional mud wall protection processes. The encoder on the robotic arm base monitors the drilling depth in real time. When the designed depth in the instruction set is reached (e.g., 8.5 meters at a certain point), the drilling operation automatically stops.

[0053] After drilling is completed, a two-stage pressure grouting procedure is seamlessly initiated. The first stage is consolidation grouting. The vehicle-mounted automatic grout mixing system automatically measures and mixes PO 42.5R grade ordinary Portland cement and water at a water-cement ratio of 0.5, generating approximately 0.5 cubic meters of homogeneous grout. The grouting pump injects the cement grout from the bottom of the pile through a grouting pipeline pre-connected to the top of the hollow pile body 1 at a constant pressure of 0.8 MPa. The grout fills the annular gap between the pile body and the borehole wall from bottom to top, expelling residual air and rock cuttings. An ultrasonic flow meter installed on the pipeline monitors the grouting volume in real time, and grouting automatically stops when a preset value is reached. The purpose of this stage is to form a preliminary bond between the pile body and the borehole wall. After waiting 6 to 8 hours for the first stage grout to initially set, the second stage, fracturing and expansion grouting, begins. The grouting system then prepares a special grout with a water-cement ratio adjusted to 0.45. A polycarboxylate-based high-efficiency water-reducing agent is added at 0.5% of the cement weight to improve fluidity, and a UEA-type micro-expansion agent is added at 3% by weight. The grouting pump raises the pressure to a high range, typically fluctuating between 2.5 and 4.0 MPa. The high-pressure grout, through a separate grouting pipe pre-embedded in the pile body, performs high-pressure fracturing, penetration, and compaction of the soil and rock mass at a specific depth around the pile. (See attached...) Figure 3 As shown, the high-pressure grout forms a bulbous enlarged head 12 around the pile and penetrates along the natural fissures or weak surfaces of the soil and rock mass, forming several root-like grout veins 13. This process greatly increases the anchoring force of the anchor body and significantly reinforces the surrounding soil and rock mass. The pressure and flow rate curves throughout the grouting process are recorded in real time and compared with the design curves in the instruction set. If a significant deviation occurs, the system will issue an alarm to prompt the operator to check.

[0054] Following the construction instruction set, the automated platform, much like a printer performing a printing task, completed the construction of all 88 anchoring units one by one, precisely and efficiently. Ultimately, a distributed anchoring grid foundation, resembling an "artificial root system," was formed on the shallow surface of the mountain, consisting of numerous composite anchor bodies deeply embedded in the ground and tightly integrated with the rock and soil.

[0055] The fourth step is the assembly of the grid-connected tie rods and the track support base. After the grout of all anchoring units has cured to 90% of its design strength (usually requiring 7 days), the installation of the ground bearing structure begins. First, a prefabricated anchor head connector 3, integrally forged from 42CrMo alloy steel, is screwed into and locked onto the exposed portion at the top of each micropile 1 using high-strength precision-rolled threads. Subsequently, a small spider crane is used to hoist the prefabricated longitudinal connecting beam 4 and transverse connecting tie rod 5 into place. The longitudinal connecting beam 4 is an H-beam of HN300x150x6.5x9 manufactured by Laiwu Steel, made of Q355B high-strength low-alloy structural steel, with all surfaces hot-dip galvanized to a zinc layer thickness of not less than 85 micrometers to ensure long-term corrosion resistance. The longitudinal connecting beam 4 is precisely placed on top of the anchor head connectors 3 in the same row. The transverse connecting rod 5 is a seamless steel pipe with an outer diameter of 114 mm and a wall thickness of 6 mm, used to connect two adjacent longitudinal connecting beams 4, thus forming a rigid spatial grid. All connections between structural components use M24 grade 10.9 torque-shear type high-strength bolts conforming to GB / T 3632 standard, and are tightened using an electric torque-shear wrench to ensure that each bolt reaches a preload of 285 kN·m, guaranteeing the rigidity and reliability of the connection nodes.

[0056] After the gridded steel structure load-bearing platform is constructed, the track support base 6 is installed on it. (See attached diagram) Figure 4 The track support base 6 is a modular, three-dimensionally adjustable component. Its structure consists of a 20mm thick base plate 8, a spherical adjustment seat 9 capable of omnidirectional rotation within a concave base, a lifting sleeve 10 with a Tr40x7 trapezoidal thread, and a top fixing saddle 11 for securing the track. The base plate 8 is fixed to the upper flange of the longitudinal connecting beam 4 by four M20 bolts. By rotating the trapezoidal thread lifting sleeve 10 with a special wrench, continuous fine-tuning of the vertical position of the track support point within a range of ±50mm can be achieved, with an adjustment accuracy of up to 0.1mm. By loosening the locking bolts and adjusting the position of the spherical adjustment seat 9, the lateral slope of the track can be precisely set within a range of ±5 degrees to meet the ultra-high requirements of curved sections.

[0057] The fifth step involves the integration of track laying with the long-term monitoring network for system status. After all track support bases 6 are installed and preliminary elevation correction is completed, standard 30 kg / m lightweight track sections 7 are hoisted onto the top fixed saddles 11 and connected and secured. Subsequently, using a Leica TS60 total station and a digital level, based on the project control network, comprehensive and precise measurements are taken of the track's horizontal position, elevation, gauge, level, and superelevation, among other geometric parameters. The measurement results are compared with the design drawings, and through meticulous fine-tuning of each track support base 6, the geometric accuracy indicators of the entire track section are ultimately superior to the design specifications. For example, the gauge error is controlled within ±1 mm, and the height difference between the two rails is less than 1 mm.

[0058] In a preferred embodiment of the present invention, a long-term health monitoring system based on distributed fiber optic sensing technology was integrated during the aforementioned construction. Distributed fiber optic grating (FBG) strain sensors were attached along the length of the micropillars 1 at selected 10% of critical locations and along the upper and lower flanges of the longitudinal connecting beams 4. These sensors can monitor the stress distribution and dynamic response of the structure in real time under train loads and environmental changes. Simultaneously, pore water pressure gauges and high-precision MEMS accelerometers were embedded in the soil and rock surrounding several anchoring points with poor geological conditions to monitor the hydrological dynamics and potential minute displacements within the slope. All sensors are connected to a solar-powered data acquisition unit installed beside the track via armored optical cables or shielded cables. This unit, through a built-in LoRaWAN wireless transmission module, packages and transmits the collected data to a remote monitoring center several kilometers away at a frequency of once per hour. This system enables 24 / 7, unattended real-time monitoring of the track-bearing structure and the stability of the surrounding slope, providing strong data support for predictive track maintenance and disaster early warning.

[0059] Example

[0060] To verify the practical effect of the method described in this invention, a typical mountainous terrain with a length of 100 meters and an average slope of 30 degrees was selected for construction. The surface of this section consists of 1.0 meter thick residual soil, below which is 6.0 meter thick strongly weathered granite, and below that is stable moderately weathered granite bedrock.

[0061] Using the method of this invention, a high-fidelity four-dimensional geological model of the section was first established through a geological survey system. Subsequently, through topology optimization design, a non-uniform layout scheme for 88 anchoring points was determined, with anchoring point depths ranging from 7.5 meters to 9.2 meters and spacing ranging from 2.2 meters to 4.8 meters. Construction was carried out using the aforementioned automated drilling and grouting integrated platform, and the installation of all 88 anchoring units and the upper grid steel structure was completed in a total of 25 working days. During construction, the total excavation volume was only about 15 cubic meters, which was only required for the platform's walking path and surface clearing of the work points. Vegetation disturbance was mainly limited to the strip area for platform walking and work, with a total area of ​​approximately 220 square meters. After the structure was installed, a loading test was conducted on the track, applying 1.5 times the design live load. Displacement gauges measured the maximum vertical settlement at the mid-span of the track to be 3.2 millimeters, far less than the design limit of 5 millimeters.

[0062] Comparative Example

[0063] For comparison, a traditional independent reinforced concrete abutment foundation scheme was used for construction on another 100-meter section of the line adjacent to it, with geological conditions basically the same as the section in the example.

[0064] According to the design, the plan involves setting up an independent foundation every 10 meters along the route, requiring a total of 11 foundations. The excavation dimensions for each foundation are 4.0 meters x 4.0 meters, with a depth of 5.0 meters, to ensure the foundation rests on stable rock strata. During construction, a 20-ton excavator will be used for extended excavation work, and temporary access roads will need to be constructed for the excavator and concrete mixer trucks. The total excavated earth and rock volume is 11 x (4.0 x 4.0 x 5.0) = 880 cubic meters. Each foundation requires approximately 20 cubic meters of C30 concrete, for a total concrete usage of 220 cubic meters. The entire construction process (including excavation, rebar tying, formwork erection, concrete pouring, and curing) will take a total of 55 working days. The construction has caused significant damage to the native vegetation of the mountain, including the excavation area and the temporary access roads, with a total disturbed area exceeding 1200 square meters. In the same loading test after completion, the maximum vertical settlement at the mid-span of the track was measured to be 4.5 mm.

[0065] Effect Comparison

[0066] To more intuitively demonstrate the superiority of the method of the present invention, the key performance indicators of the embodiments and comparative examples are quantitatively compared, and the specific data are shown in the table below:

[0067] Comparison Projects Example (Method of the Invention) Comparative Example (Traditional Independent Basis Approach) Effect Analysis Total construction period (working days) 25 55 The construction period was shortened by 54.5%. Total excavated earth and rock volume (cubic meters) 15 880 The amount of excavation was reduced by 98.3%, resulting in minimal disturbance to the mountain. Concrete usage (cubic meters) 0 220 No concrete is needed, reducing material transportation and on-site mixing pollution. Total consumption of slurry and steel (tons) 28.5 45.2 (Reinforcing steel only) The amount of main materials used has been significantly reduced. Area of ​​vegetation disturbance (square meters) 220 1200 Significant results in ecological and environmental protection Maximum settlement (mm) during loading test 3.2 4.5 Higher structural stiffness and stability Construction worker requirements (persons) 4 (Platform Operation and Assistance) 15 (Multi-task collaboration) High degree of automation reduces labor costs and safety risks. Slope reinforcement effect Active reinforcement None, or even weaken. Integrating slope protection functions enhances the long-term safety of the line.

[0068] In summary, the mountain electric rail track laying method provided by this invention fundamentally changes the traditional mountain rail construction model through a series of innovative technological integrations. It solves the design and construction challenges of track load-bearing structures under complex geological conditions in a minimally invasive, precise, efficient, and eco-friendly manner. Its comprehensive advantages in construction efficiency, environmental protection, structural performance, and long-term safety are obvious, demonstrating extremely high engineering application value and promising prospects for widespread adoption.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for laying electric rail tracks in mountainous areas, characterized in that, Includes the following steps: The first step is to construct a high-fidelity four-dimensional geological information model along the track. The four-dimensional geological information model includes the three-dimensional geometric information of the mountain, the internal geological structure information, the mechanical parameters of the rock and soil, and the hydrological status information. The second step: Based on the high-fidelity four-dimensional geological information model, an adaptive anchoring grid layout optimization design is carried out, and a digital construction instruction set that defines the spatial position, drilling attitude and grouting process parameters of each anchoring unit is generated through numerical simulation. The third step: Based on the digital construction instruction set, the automated construction platform is used to carry out the serial construction of the micro-invasive anchoring unit, and a distributed anchoring grid foundation composed of multiple composite anchor bodies (2) deeply embedded in the rock and soil is constructed in the shallow surface of the mountain. Fourth step: On the basis of the distributed anchoring grid, assemble the gridded connecting rods and the track support base (6) with three-dimensional precision adjustment function to form an integral load-bearing structure system; Fifth step: Lay the track row (7) on the track support base (6), and make precise adjustments to the track support base (6) so that the geometric accuracy of the track line meets the design requirements.

2. The method for laying mountain electric rail tracks according to claim 1, characterized in that, The steps in the first step of constructing a high-fidelity four-dimensional geological information model specifically include: An integrated geological survey data acquisition system is used to collect data along a predetermined route. The geological survey data acquisition system integrates a high-precision Global Navigation Satellite System (GNSS) receiver, a fiber optic gyroscope inertial measurement unit (IMU), and a ground-penetrating radar (GPR) array. By tightly coupling the data from the GNSS receiver and the IMU, high-precision three-dimensional terrain data of the earth's surface is obtained, and centimeter-level spatial position and attitude information is provided for each detection data point of the ground-penetrating radar (GPR) array. The ground-penetrating radar (GPR) array is used to collect electromagnetic wave reflection signals from underground, and the electromagnetic wave reflection signals are converted into dielectric constant distribution data of the underground medium through an inversion algorithm. Based on a pre-defined empirical relationship model between the dielectric constant of soil and physical and mechanical parameters, the dielectric constant distribution data is transformed into three-dimensional geological structure data containing information on soil stratification, fracture distribution, and mechanical parameters. The high-precision three-dimensional topographic data of the surface is registered and fused with the three-dimensional geological structure data of the underground to generate the high-fidelity four-dimensional geological information model.

3. The method for laying mountain electric rail tracks according to claim 1, characterized in that, The specific steps in the second step of adaptive anchoring mesh layout optimization design include: The high-fidelity four-dimensional geological information model is imported into finite element analysis software to establish a refined three-dimensional solid model that can reflect the real geological conditions along the track, and different rock and soil masses in the model are assigned corresponding material properties. A preset track load is applied to the three-dimensional solid model. The track load includes the track structure's self-weight, the train's dynamic load, and the environmental load. The topology optimization algorithm is initiated, and the optimization objective function is set to minimize the total material consumption of the anchoring grid system under the premise of satisfying the deformation limit of the track structure and the stress safety threshold of the structural system and the soil and rock mass. The constraints of the topology optimization algorithm are set, including the minimum spacing of anchoring units, the maximum drilling depth, and the avoidance of specific geologically vulnerable areas. Through algorithm iteration, the optimal force transmission path is automatically identified, a non-uniformly distributed array of anchoring points is generated, and the final output is the digital construction instruction set containing the unique ID, three-dimensional coordinates, borehole azimuth angle, borehole inclination angle, design hole depth and grouting parameters of each anchoring unit.

4. The method for laying mountain electric rail tracks according to claim 1, characterized in that, The specific steps for sequential construction of the minimally invasive anchoring units in the third step include: It adopts an automated drilling and grouting integrated platform that integrates an autonomous navigation and positioning system, a six-axis articulated robotic arm, integrated drilling tools, an automatic grouting system and a high-pressure grouting pump; The platform autonomously navigates to the predetermined construction location and automatically levels and locks it based on the coordinate data in the digital construction instruction set. The central controller of the platform drives the six-axis articulated robotic arm to precisely adjust the spatial attitude of the integrated drill bit so that its axis coincides with the drilling azimuth and inclination angle set in the instruction set. The drilling process is carried out by micro-disturbance casing drilling. At the same time as drilling, the hollow steel pipe (1) serving as the micro pile rod is simultaneously placed into the hole and the slag is discharged by high-pressure air. After the borehole reaches the designed depth, a preset two-stage pressure grouting process is performed to form the composite anchor body (2) that is tightly bonded to the surrounding rock and soil.

5. The method for laying mountain electric rail tracks according to claim 4, characterized in that, The two-stage pressure grouting process specifically includes: The first stage is consolidation grouting: using a lower grouting pressure, ordinary cement grout with a predetermined water-cement ratio is injected through the bottom of the hollow micro pile body (1) to fill the annular gap between the micro pile body (1) and the hole wall from bottom to top, forming a preliminary bond; The second stage is splitting and expansion grouting: After the initial setting of the grout in the first stage, a high grouting pressure is used to inject special cement grout mixed with high-efficiency water-reducing agent and micro-expansion agent through the pre-embedded grouting pipe to split, compact and penetrate the rock and soil around the micro pile body (1), thereby forming a bulb-shaped enlarged head (12) and several grout veins (13) that penetrate into the cracks of the rock and soil around the micro pile body (1), so as to significantly improve the anchoring force and reinforce the rock and soil around the pile.

6. The method for laying mountain electric rail tracks according to claim 1, characterized in that, The fourth step, assembling the gridded connecting rods and track support base (6), specifically includes: A prefabricated anchor head connector (3) is installed on the exposed portion of the top of the micropile body (1) of each of the composite anchor bodies (2). The prefabricated longitudinal connecting beam (4) is placed on the anchor head connector (3) in the same column and connected by high-strength bolts; Prefabricated transverse connecting rods (5) are used to connect adjacent longitudinal connecting beams (4) and are connected by high-strength bolts to form a spatial gridded steel structure load-bearing platform; The track support base (6) is installed at a predetermined position on the upper flange plate of the longitudinal connecting beam (4).

7. The method for laying mountain electric rail tracks according to claim 6, characterized in that, The track support base (6) is a modular component, and its structure includes: A base plate (8) for fixing to the longitudinal connecting beam (4); A spherical adjustment seat (9) is set on the base plate (8) and can rotate omnidirectionally in the concave base, for the precise setting of the transverse slope of the track; A trapezoidal threaded lifting sleeve (10) that is connected to the spherical adjusting seat (9) allows for millimeter-level adjustment of the vertical position of the track support point by rotating the lifting sleeve (10); A top fixing saddle (11) is provided on the top of the trapezoidal threaded lifting sleeve (10) for fixing the track row (7).

8. The method for laying mountain electric rail tracks according to any one of claims 1 to 7, characterized in that, It also includes the step of integrating a long-term health monitoring system during the construction process, the steps of which specifically include: Distributed fiber optic grating (FBG) strain sensors are deployed on the micropillars (1) and longitudinal connecting beams (4) at selected key locations to monitor the stress distribution and changes of the structure during operation. A pore water pressure gauge and a microelectromechanical system (MEMS) accelerometer are installed in the soil and rock surrounding a specific composite anchor body (2) to monitor the internal hydrological state and minute vibrations of the slope. All sensors are connected to the data acquisition unit, and the collected data is periodically sent to the remote monitoring center via a wireless transmission module based on low-power wide-area IoT technology, so as to realize real-time monitoring and predictive maintenance of the track bearing structure system and the stability of the surrounding slope throughout the entire life cycle.

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