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ABSTRACT In order to evaluate the vibration response of the slab track with damage more efficiently in high speed railway, a periodic nonlinear dynamic model with implicit solving method for [...]

ABSTRACTThis study aims to investigate the durability and microstructure of cement-sodium silicate grouts with high water to binder ratios (w/b) of 1.1-2.5 upon exposure to sea water. Grout specimens were [...]

ABSTRACT For evaluating the vibration response of the damaged slab track efficiently, a novel explicit periodic nonlinear model for the damaged slab track in high speed railway involving material nonlinearity [...]

Excavating super-large-span tunnels in soft rock masses presents significant challenges. To ensure safety, the sequential excavation method is commonly adopted. It utilizes internal temporary supports to spatially partition the tunnel face and divide the excavation into multiple stages. However, these internal supports generally impose spatial constraints, limiting the use of large-scale excavation equipment and reducing construction efficiency. To address this constraint, this study adopts the “Shed-frame” principle to explore the feasibility of an innovative support system, which aims to replace internal supports with prestressed anchor cables and thus provide a more spacious working space with fewer internal obstructions. To evaluate its effectiveness, a field case involving the excavation of a 24-m span tunnel in soft rock is presented, and an analysis of extensive field data is conducted to study the deformation characteristics of the surrounding rock and the mechanical behavior of the support system. The results revealed that prestressed anchor cables integrated the initial support with the shed, creating an effective “shed-frame” system, which successively maintained tunnel deformation and frame stress levels within safe regulatory bounds. Moreover, the prestressed anchor cables bolstered the surrounding rock effectively and reduced the excavation-induced disturbance zone significantly. In summary, the proposed support system balances construction efficiency and safety. These field experiences may offer valuable insights into the popularization and further development of prestressed anchor cable support systems.

ABSTRACT Based on the theory of vehicle-track coupling dynamics, a plane stress finite-infinite element model of a high-speed railway subgrade-bridge transition zone is proposed. With this model, the influence of [...]

When dynamic load is applied on a granular assembly, the time-dependent dynamic load and initial static load (such as gravity stress) act together on individual particles. In order to better understand how dynamic load triggers the micro-structure's evolution and furtherly the ensemble behavior of a granular assembly, we propose a criterion to recognize the major propagation path of dynamic load in 2D granular materials, called the “dynamic force chain”. Two steps are involved in recognizing dynamic force chains: (1) pick out particles with dynamic load larger than the threshold stress, where the attenuation of dynamic stress with distance is considered; (2) among which quasi-linear arrangement of three or more particles are identified as a force chain. The spatial distribution of dynamic force chains in indentation of granular materials provides a direct measure of dynamic load diffusion. The statistical evolution of dynamic force chains shows strong correlation with the indentation behaviors.

Cyclic load is widely adopted in laboratory to simulate the effect of train load on ballast bed. The effectiveness of such load equivalence is usually testified by having similar results of key concerns of ballast bed, such as deformation or stiffness, while the consistency of particle scale characteristics under two loading patterns is rarely examined, which is insufficient to well-understand and use the load simplification. In this study, a previous laboratory model test of ballast bed under cyclic load is rebuilt using 3D discrete element method (DEM), which is validated by dynamic responses monitored by high-resolution sensors. Then, train load having the same magnitude and amplitude as the cyclic load is applied in the numerical model to obtain the statistical characteristics of inter-particle contact force and particle movements in ballast bed. The results show that particle scale responses under two loading patterns could have quite deviation, even when macro-scale responses of ballast bed under two loading patterns are very close. This inconsistency indicates that the application scale of the DEM model should not exceed the validation scale. Moreover, it is important to examine multiscale responses to validate the effectiveness of load simplification.

ABSTRACTThe discrete element method is widely adopted to investigate the micro-mechanism of degradation and reinforcement of ballast tracks. Generally, numerical parameters of ballast particles are examined by macro characteristics obtained in field or indoor tests, while particle-scale responses are rarely examined due to the difficulties in practical measurement. In this study, we demonstrate the importance of examining particle movements in modelling ballast bed via discrete element method. A previous laboratory model test is repeated via Particle Flow Code, where 25 sets of damping coefficients are assigned. The results show that the variation of damping coefficients has more significant influence on particle movements than the macroscopic behaviours of ballast and ballast beds. According to the three-dimensional motion characteristics of ballast particles obtained using a SmartRock sensor, the appropriate local damping constant and critical contact damping ratio are suggested for typical loading frequencies.

ABSTRACTBallast bed deformation is significantly influenced by its internal stress state. However, investigations concerning ballast bed deformation focus mainly on the deformation behaviour under various external loading conditions or ballast states, where the influence of load diffusion variation has rarely been considered directly. In this work, a full-scale model test was established to obtain simultaneously the external deformation and the internal stress of ballast bed, with respect to various loading conditions (equivalent axle load 14–30 t, 3–6 Hz). The results show that both average stress and stress ratio on ballast increase with loading magnitude. Meanwhile, a larger proportion of vertical load concentrates within the sleeper projection area. Accordingly, the plastic (elastic) deformation is more (less) sensitive to the load variation at larger wheel–rail load. Besides, the dynamic stiffness increases gradually with loading amplitude while showing a small drop as loading frequency increases.

Forced vibration of underground structures is a common activity during the construction or service period of rail infrastructure, such as vibro piling, the vibration of piles, and tunnel lining under moving train loads, etc. To better predict the structure’s performance under vibration, a lot of attention has been paid to investigating the behavior of interfaces between soils and structures. However, limited by the capabilities of the current test apparatus, the soil-structure interface friction is mainly determined under static and low-frequency cyclic loading conditions. While for dynamic conditions, the interface friction is generally configured as a reduction of the static friction coefficient. By now, the interface friction under vibration is not fully addressed, especially under high-frequency vibration. In this study, an apparatus is developed from a direct shear device to test the interface friction variation between soil and structure under vibration. Static and vibration forces are imposed on the structure to implement coupled monotonic shear and high-frequency vibration to the interface. The apparatus allows for the controlling of soil property, surface property of structure, normal stress, shear rate, and vibration intensity and frequency. The variation of shear stress and displacement, normal stress ,and displacement are mainly monitored. To show the capability and test procedure of the developed apparatus, dry sand and a smooth-steel plate are installed and tested on the apparatus with a vibration frequency 45 Hz and an acceleration of 0–0.15 g. The results show that the apparatus can stably obtain the friction weakening of the sand-steel interface, including the reduction of shear strength, volume change, and shear-displacement slip.

Construction issues of high-speed rail infrastructures have been increasingly concerned worldwide, of which the subgrade settlement in soft soil area becomes a particularly critical problem. Due to the high compressibility and low permeability of soft soil, the post-construction settlement of the subgrade is extremely difficult to control in these regions, which seriously threatens the operation safety of high-speed trains. In this work, the significant issues of high-speed railway subgrades in soft soil regions are discussed. The theoretical and experimental studies on foundation treatment methods for ballasted and ballastless tracks are reviewed. The settlement evolution and the settlement control effect of different treatment methods are highlighted. Control technologies of subgrade differential settlement are subsequently briefly presented. Settlement calculation algorithms of foundations reinforced by different treatment methods are discussed in detail. The defects of existing prediction methods and the challenges faced in their practical applications are analyzed. Furthermore, the guidance on future improvement in control theories and technologies of subgrade settlement for high-speed railway lines and the corresponding challenges are provided.

Jet grouting piles were widely employed for ground reinforcement in building and infrastructure engineering due to the low cost and construction convenience. However, this foundation treatment method is not allowed to be used in high-speed railway involved constructions in China because of the concerning of the negative effect on the lateral displacement of the existing high-speed railway. To find a reasonable application distance of jet grouting piles away from existing high-speed railway bridge in deep soft soils with medium sensibility, a series of laboratory and in-situ tests on the influence of the jet grouting piling on the deformation of surrounding soils and adjacent high-speed railway bridge are carried out. The geological characteristics of the construction site and the mechanical properties of the soft soil are deeply investigated by utilizing field and laboratory tests. The piling induced lateral displacement of the surrounding soils is monitored as well as the displacement of an adjacent high-speed railway bridge. The monitoring data reveal that the influence area of the jet grouting piling is approximately 1.75 ∼ 1.85 times of the pile length in deep soft soils. The critical distance of the jet grouting piles from the existing high-speed bridge should be larger than 2 times of the pile length.

A shield tunnel can be damaged by shield shell extrusions, such as shield tunnel floating, which may cause contact (even a squeezing action) between the shield tunnel and shield shell. To fully analyze this problem, a detailed 3D-finite element model (FEM) of a shield tunnel under the effect of a squeezing action in the shield tail, soil pressure, jacking force, and grouting pressure, was established by applying a plastic-damage constitutive model of concrete. A full-scale test of three segment rings was conducted, and the test results verified the feasibility of the constructed FEM. In this study, different squeezing positions and deflection angles of the shield shell were analyzed. The results indicated that the area squeezed by the shield shell experienced the most damage, and the tensile damage to a segment reduced gradually as the squeezing position approached the circumferential seam. The damage range gradually increased with the increase in deflection angle. The effect of the squeezing position of the shield shell on the bending moment was larger than the effect of the deflection angle on the bending moment. However, the effect of the squeezing position and that of the deflection angle on the shear force were the same.

This paper presents a three-dimensional model for the calculation of train-induced vibration of a floating slab track in an underground tunnel based on the integration of a semi-analytical approach and a dynamic substructure method. The methodology for the train-floating slab track–tunnel–soil coupled model is described and validated by comparing the vibration response of the system with that of the Pipe-in-Pipe model. The innovations of the proposed model include the following: (1) it considers all components of the metro train-induced vibration problem including the train, the floating slab track, the tunnel, the soil and the interactions of the subsystems; and (2) it operates in the time domain and thus is capable of modelling the highly non-linear loading behaviours (i.e. the wheel/rail contact relationship). A hypothetical example is presented to illustrate the vibration isolation effect of the floating slab track using the developed model, and the following conclusions can be drawn. Excellent vibration isolation performance is observed for the floating slab track system, especially for vibrations at a high frequency (above 12.5 Hz), whereas the vibration is amplified near the natural frequency of the floating slab (i.e. 8 Hz in this study) because of the resonance effect. The amplitudes of the soil stresses are reduced due to the floating slab track system, especially for the high-frequency soil stresses.

This study proposed an improved tunnel model for the evaluation of dynamic stress of the saturated soil subjected to vertical and horizontal moving loads. Based on this model, the response of dynamic stress of the saturated soil subjected to three typical loading scenarios is systematically analysed: (1) vertical moving loads, (2) combined vertical moving load and longitudinal horizontal load due to the braking of a train, and (3) combined vertical moving load and tangential horizontal load during the turning of a train at small curved sections. The simulated results reveal that soil permeability, load speed and load frequency have a significant influence on the dynamic stress of the saturated soil. The two types of horizontal loads have considerable effects on the shear stress but have negligible influence on the normal stress and pore-water pressure of the saturated soil.

This paper presents an efficient method for the prediction of vibrations induced by underground railways in a poroelastic half-space. The proposed method accounts for both the saturated porous characteristic of the soil and the free surface effect. An analytical tunnel model, which is coupled with a train-track system, is firstly developed to calculate the dynamic response of the tunnel–soil interface in a poroelastic full-space. By assuming that the near field response of the tunnel is not affected by the existence of the free surface, vibrations of the poroelastic half-space is then calculated by the two-and-a-half-dimensional (2.5-D) boundary integral equation for saturated porous media along with the Green's function for a poroelastic half-space. Soil vibrations generated by the quasi-static and dynamic train load are presented. It is found that an increase of the soil permeability leads to a decrease of the soil displacement. A saturated soil model may be more suitable for calculating the train-induced vibration in water-rich region. Isolation effectiveness of a float slab is also investigated. The simulation results show that floating the track slab can moderately induces the ground vibration, but also causes more transmission of vibration under certain conditions. [ABSTRACT FROM AUTHOR]

Uneven subgrade settlement associated with rail deflection occurs mainly in the bridge–embankment transition zones of high-speed railways. An iterative method of computation is proposed for studying such uneven settlement in these zones. A vehicle–track–subgrade model is used to investigate the vehicle–track interactions and the deviator stress field of the transition zone, and a soil cumulative plastic strain model is used to obtain the deterioration process of uneven settlement in the transition zone. Results indicate that uneven settlement caused by train loads in the transition zone tends to plateau at 40,000 repeated load applications. Subgrade settlement changes abruptly in the first measured 5 m, as well as from 25 to 30 m from the abutment; these two regions should be adequately strengthened and should receive more attention for track maintenance.

The complete dynamic two-and-a-half-dimensional (2.5-D) Green's function for an internal point load or fluid source buried in a layered poroelastic half-space is derived and applied to the 2.5-D boundary element method (BEM) in this paper. Based on Biot's theory, the general solutions are derived using the potential decomposition method and the Fourier transform. Utilizing the boundary conditions of the free surface, interfaces and bottom half-space, as well as the general solutions, the complete 2.5-D Green's function for a layered poroelastic half-space is obtained using the transmission and reflection matrix (TRM) method. The solutions presented in this paper are free of numerical instability for the high frequency and large layer thickness. The proposed 2.5-D Green's function is verified by comparison with the existing solutions. A case study of calculating vibrations from a semi-circular tunnel embedded in a layered poroelastic half-space is presented using the 2.5-D BEM along with the proposed 2.5-D Green's function. The layer interfaces and the surface of the poroelastic half-space no longer have to be meshed, avoiding spurious reflections at mesh truncations. The boundary element mesh can be limited to the surface of the tunnel, significantly reducing the size of the boundary element mesh. [ABSTRACT FROM AUTHOR]

The construction of non-ballasted slab railway track on existing subgrade soils, or on embankments, is at an early stage of development on Chinese railways. Developing appropriate standards for the allowable amount of subgrade differential settlement that takes into account the dynamic response of the train–track system is one of a number of issues that need to be addressed. To inform the development of such standards, a model based on the theory of vehicle–track coupling dynamics, which considers the weight of the track structure, was created to investigate how differential settlement, in terms of the amplitude, wavelength and position of the settlement along the track, can affect various railway performance-related criteria, including ride quality, stability, vehicle safety and potential damage to the wheel of the train and the rail (i.e. forces at the wheel–rail contact and in the fasteners). The performance of the model was favorably compared with other widely used models described in the literature. The analysis of the study to inform design standards using the developed model demonstrated that the magnitude of the differential settlement influences passenger comfort the most compared with other performance criteria. For the considered CRTS I track, there exists a particular wavelength (8 m for the specific conditions considered) that results in all measures of performance being at their maximum values. Furthermore, the longitudinal position of the settlement waveform in relation to the joints between two concrete slabs, a factor which is not considered in design standards, was shown to influence component deterioration, passenger comfort and safety. The greatest propensity to cause component damage occurs when the beginning or end of the differential settlement waveform corresponds with the inter-slab joint of a concrete base. Accordingly, it is recommended that current design standards should be modified to specify appropriate combinations of amplitude, wavelength and position of the differential settlement to give acceptable measures of performance.

Uneven settlement and variation in track stiffness are inherent issues of culvert–embankment transition zones. Therefore, the construction of a shield tunnel (a temporary support structure for tunnel construction) in the vicinity of a transition zone may aggravate track geometry deterioration, increase maintenance demand, and cause poor ride quality. This study investigated the influence of shield tunnel construction on the distribution of soil dynamic stress. A construction project of shield tunnels for a metro line beneath an existing railroad was employed as a case study. A plane strain model that was realized by the finite element analysis method was employed to investigate the distribution discipline of the soil dynamic stress in transition zones, which was induced by the passing train and the shield tunnel beneath the railway. The results indicate that the existence of a shield tunnel structure will increase the soil dynamic stress in the transition zone. Because of the tunnel structure, the soil dynamic stress is 38% greater than the soil dynamic stress in the case without a tunnel at a depth of 16 m. Consequently, a recommended treatment is introduced according to the properties of the surrounding soil. Numerical simulation revealed that this treatment is appropriate for reducing the soil dynamic stress in a transition zone.

The dynamic two-and-a-half-dimensional (2.5-D) Green׳s function for a poroelastic half-space subject to a point load and dilatation source is derived based on Biot׳s theory, with the consideration of both a permeable surface and an impermeable surface. The governing differential equations for the 2.5-D Green׳s function are established by applying the Fourier transform to the governing equations of the three-dimensional (3-D) Green׳s function. The dynamic 2.5-D Green׳s function is derived in a full-space using the potential decomposition and discrete wavenumber methods. The surface terms are introduced to fulfil the free-surface boundary conditions and thereby obtain the dynamic 2.5-D Green׳s function for a poroelastic half-space with the permeable and impermeable surfaces. The half-space 2.5-D Green׳s function is verified through comparison with the 2.5-D Green׳s function regarding an elastodynamic half-space and the 3-D Green׳s function for a poroelastic half-space. A numerical case is provided to compare between the full-space solutions and the half-space solutions with two different sets of free-surface boundary conditions. In addition, a case study of efficient calculation of vibration from a tunnel embedded in a poroelastic half-space is presented to show the application of the 2.5-D Green׳s function in engineering problems. [ABSTRACT FROM AUTHOR]

Due to the excellent drainage performance of the ballast, existing studies mainly focus on the dynamic response of ballast under field capacity or saturation. Attention has rarely been paid to dynamic changes in moisture content and potential influences. In this article, we firstly conduct a model test to determine the variation of ballast moisture content under artificial rainfall. After that, a full-scale model test with cyclic loading is carried out to study the effect of moisture content variation on the macro-microscopic response of the ballast bed, where several wireless particle sensors are installed to obtain ballast motion characteristics at strategic locations. The results show that the moisture content increases gradually and stabilizes at a flat peak under rainfall, despite the excellent drainage performance of ballast bed. After halting rainfall, the moisture content drops back to field capacity, which indicates dynamic flowing surface water on ballast particles under rainfall. Such flowing surface water brings changes to the original dynamic equilibrium of ballast bed: macroscopically, the deformation rate of stabilized ballast bed increases significantly, reaching a local peak under field capacity; microscopically, the x- and z-angular accelerations of the ballast show positive correlation with rainfall intensity. The multiscale responses indicate that field capacity is a critical moisture content.

Segment uplift is a frequent problem during the construction of shield tunnels. This article presents a full-scale field test to study the influence factors of segment uplift, such as chamber pressure, advance rate, vertical component force of total thrust and grouting pressure and grout composition. This paper proposes a tunnel segment uplift calculation model of earth pressure balance shield based on a series of in situ tests in the typical soft soil stratum in China. The test results show that grouting pressure and grout composition have significant impacts on the segment uplift. However, the influences of chamber pressure, advance rate and total thrust are insignificant for the uplift. The analysis data based on the calculation model correspond well with the monitoring data in the shield tunnelling construction. By comparison, the deviation rate ranges from −19% to +15%.

This paper presents a method for modeling the ground vibrations from a railway tunnel in layered unsaturated soil, considering the uncertainty and spatial variability of soil parameters. A deterministic ground vibration prediction model, which is an improved Euler beam model, is developed to evaluate the vibrations for a tunnel in layered unsaturated soil. Furthermore, the spatial variability of soil parameters is simulated by random fields using the Monte Carlo theory and the middle point method of Cholesky decomposition. By coupling the random fields of soil parameters to the deterministic vibration prediction model, the effect of uncertainty and spatial variability of soil on the ground vibrations is demonstrated through a case study. It is found that the variability of soil parameters has little influence on the spatial distribution regularities of ground vibrations, but it has a significant effect on the dynamic response amplitude and the critical velocity of the system.

Abstract: The (Ba1−xSrx)TiO3 (BST) ferroelectric thin films exhibit outstanding dielectric properties, even at high frequencies (>1 GHz), and large, electric-field dielectric tunability. This feature makes them suitable for developing a new class of tunable microwave devices. The dielectric properties and dielectric tuning property of BST thin films are closely related to the film compositions, substrate types, and post-deposition process. The successful implementation of BST films as high-frequency dielectrics in electrically tunable microwave devices requires a detailed understanding of both their processing and material properties. This paper will review the recent progress of BST thin films as active dielectrics for tunable microwave devices. The technical aspects of BST thin films, such as processing methods, post-annealing process, film compositions, film stress, oxygen defects, and interfacial structures between film and substrate, are briefly reviewed and discussed with specific samples from the recent literature. The major issues requiring additional investigations to improve the dielectric properties of BST thin films for tunable microwave applications are also discussed.

Piezoelectric ceramic actuators and materials play a key role in the development of advanced precision engineering. The breakthroughs in this field are closely related to the development of various types of piezoelectric ceramic actuators and related materials. The likelihood that the range of applications and demand for actuators will grow quickly has stimulated intensive researches on piezoelectric ceramics. Functionally gradient materials (FGMs) are new classes of composites characterized by compositional and/or microstructural gradation over macroscopic/microscopic distances. This constitutional gradation can be tailored to meet specific needs while providing the best utilization of composite components. Furthermore, FGMs technology is also a novel interfacial technology to solve the problems associated with the sharp interface between two dissimilar materials. In recent years significant advances in the development of FGMs have been achieved. In this paper, we first briefly review the recent progress of ceramic actuators and developments of piezoelectric materials, and then focus on summarizing typical applications of functional gradients in piezoelectric and ferroelectric materials.

A novel pile-plank-supported ballastless tram track is employed in southeast of China to mitigate the foundation differential settlement in soft soil regions. In this structure, the channel rails are directly combined with the plank by fasteners and pads. In situ measurement data reveal that the foundation differential settlement is well controlled by this structure and the internal forces of the plank mainly depend on temperature variation. To assess the structural safety and improve the reinforcement design for the pile-plank structure, an efficient and precise calculation algorithm for internal forces of the structure is urgently required. In this work, a one-dimensional (1D) model is proposed to evaluate the longitudinal forces of the embedded pile-plank structure due to temperature variation. The constraints of rails and surrounding concretes (i.e., overlying pavement and the supporting layer) on the embedded structure are considered. The semi-analytical solution of this model is derived and a comprehensive calculation procedure is proposed. Based on the project of Shanghai Tram Line T1, a case study is undertaken to validate the proposed model. The results indicate that the maximum longitudinal displacement of the plank increases with the temperature variation. The critical displacement appears when the temperature variation rises to 15 ℃. The calculated longitudinal forces of the plank are in accordance with the in situ measurement data. This model provides a strong base to the reinforcement design of the pile-plank-supported ballastless tram track.

With the rapid increase of urban rail transit networks, the environmental problems induced by vibrations from subway traffic become more and more prominent. Most subway tunnels are constructed by the shield machine, which are assembled by tunnel linings connected by joints. This study investigates the effect of the tunnel longitudinal joints on the train-induced vibrations from a subway shield-driven tunnel in a homogeneous half-space. The shield-driven tunnel is considered as an elastic lining ring connected by longitudinal joints, while the ground is simplified as a homogeneous elastic half-space. The general solution for the tunnel and the ground are derived by using the thin-shell theory and the elastic continuum theory, respectively. By satisfying the boundary conditions on the tunnel-ground interface, the tunnel is coupled to the ground in a half-space domain. The responses during the running of a metro train are calculated by coupling the tunnel-ground model with the vehicle-track model. The longitudinal joint has a significant impact on ground vibrations, which increases the running RMS values of the vertical velocity by 20% ∼ 70% and of the horizontal verticity by 10% ∼ 20%. As the stiffness of the longitudinal joint decreases, the ground vibrations increase.

In recent years, a large number of tram–tracks have been constructed in typical soft soil area of China. Infrastructure defects due to the differential foundation settlement are serious issues in this area. To ensure the operation safety of the tram, the influence of different infrastructure defects on the dynamic response of the tram–track system has been investigated in this paper. A dynamic model of a five-module 100% low-floor tram vehicle coupled with a slab track system is developed based on a finite element (FE) method and multibody kinematics. The articulation between different vehicle modules, the wheel–rail nonlinear contact, pad failures, and a cavity in the subgrade have been taken into account in this model. The dynamic response of the vehicle–track coupling system to different operation speeds and infrastructure defects are calculated. Results indicate that the vibration energy of the vehicle body is mainly distributed in the frequency range below 1.5 Hz. This frequency range should be paid special attention in the durability design for the vehicle structure. When the number of the failure pads is larger than 3, the pad failure in tram–track has significant influence on the system dynamic response. A cavity in subgrade has a limited effect on high frequency vibrations (above 100 Hz) of the rail, while the low frequency vibrations (below 75 Hz) of the rail can be obviously increased by cavities in subgrade. The model can be used in the optimization of suspension parameters and the tram vehicle–track coupled vibration analysis.

Experimental results are reported for the permanent photoinduced rotation of the principal axes of the birefringence in a circular-core single-mode optical fiber on exposure of the fiber to powerful argon-laser radiation at 488 nm. The linearly polarized laser beam was launched into the fiber along one of the principal axes of the initial birefringence in the fiber. After several exposures totaling 4 h, a rotation of as much as 57° was observed in the orientations of the principal axes in addition to the photoinduced birefringence.

• A TLM-CFSPML for 3D dynamic responses of a layered TI saturated half-space is proposed. • The 3D fundamental solution for dynamic sources acting on a layered TI saturated half-space is derived. • The key parameters involved in the CFSPML for an unbounded saturated TI medium are systematically analyzed. This paper establishes an efficient model for simulating wave propagation in a multi-layered transversely isotropic (TI) saturated medium. The complex frequency shifted perfectly matched layer (CFSPML) is integrated into the thin layer method (TLM) framework to address instability issues associated with the classical PML in TI media. The three-dimensional closed-form fundamental solution for dynamic sources acting on a layered TI half-space is derived in the frequency-space domain. By eliminating the necessity of double discrete Fourier transform of spatial coordinates, this approach provides an efficient and accurate tool for exploring wave propagation in saturated soils. Numerical examples are conducted to determine the parameters involved in CFSPML for an unbounded TI saturated medium across various material anisotropy ratios, including the total thickness of CFSPML domain H PML , the parameter Δ γ related to the number of CFSPML elements, and the reflection coefficient within the discrete CFSPML domain R 0. A comprehensive investigation systematically analyses the effect of material anisotropy on dynamic responses. Numerical studies highlight that the anisotropy in the shear modulus exerts the most substantial influence on the dynamic response, followed by Young's modulus and the permeability coefficient. The effect of permeability coefficient anisotropy cannot be disregarded, particularly in the context of fluid sources. [ABSTRACT FROM AUTHOR]