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Large deformation is a kind of geological hazard in the construction of soft rock tunnels, which hinders construction, threatens workers' safety, and raises project costs. Accurately obtaining the large deformation characteristics and patterns of tunnels is the prerequisite for taking targeted support measures. First, a viscoelastic–plastic model that can simulate both the short-term strain-softening effect and the long-term creep effect was proposed to investigate the large deformation features of soft rock tunnels. Then, a sophisticated model for creep parameter inversion was developed using the support vector machine, genetic algorithm, and particle swarm optimization. Finally, the deformation, stress, plastic zone, and internal forces in the lining of a large deformation tunnel were determined using the proposed constitutive model and the creep parameters obtained by inversion. As the creep displacement only makes up 14.4–23.2% of the total displacement, the results demonstrate that the elastic–plastic displacement is much more than the creep displacement. Notably, the connection between the top and middle benches has the most pronounced horizontal movement, accompanied by a significant strain-softening effect, which ultimately becomes the weak point in the support system. The excavation disturbs the surrounding rock, causing a high-stress zone and a low-stress zone, with the interface located around the junction of the elastic and plastic zones. The bending moment is positive at the wall waist and negative at the vault and arch waist. In addition, there is a progressive rise in the bending moment from negative to positive at the arch foot. [ABSTRACT FROM AUTHOR]

• An orbit-attitude-structure-thermal coupled modelling method is proposed. • A unified-meshes ANCF element for temperature-displacement field is proposed. • Both axial and circumferential heat conduction are considered. • Three quasi-static models are proposed to predict the thermally induced vibration. Large space structures would exhibit orbit-attitude-structure-thermal coupled effects in complicated space environment. Thus, a new thermal-structure coupled modelling method is proposed using gradient-deficient absolute nodal coordinate formulation beam elements. Compared to the previous methods, both axial and circumferential heat conduction are considered. The cubic interpolation in temperature field instead of the linear interpolation is adopted to obtain a unified-mesh temperature-displacement description. The gravitational force and gravity gradient are modelled, and the effects of attitude motion and structural deformation on solar radiation intensity are considered. In addition, three kinds of quasi-static thermal-structure coupled models are proposed based on Euler-Bernoulli beam theory. Based on the quasi-static models, the theoretical formulas are derived to effectively predict the thermally induced vibrations of the beam in space. Four numerical examples are studied to validate the proposed models, including the heat conduction examples with three boundary conditions and a thermal-structure coupled cantilever beam example. Based on the proposed formulation, the orbit-attitude-structure-thermal coupled dynamics of a multibody system consisted of a rigid body and a large flexible appendage is investigated considering the gravity gradient, solar radiation, Earth's shadow, and self-shadow. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The auxetic structure with negative Poisson's ratio has broad application prospects in many engineering fields. Although it is often simplified as a linear elastic problem in theoretical models, the generally used slender structure, such as the reentrant honeycombs, will inevitably undergo large deformation resulting in significant non-conservative load effects in the service conditions. Therefore, a numerical framework for modeling nonlinear deformation of the auxetic structures under follower loads with the complex variable element-free Galerkin method is developed in this paper. The application of the complex variable meshfree method is to deal with the numerical difficulties caused by mesh distortion that may occur in large deformation problems, and at the same time, it can improve the construction efficiency of meshfree shape functions through the complex variable moving least-squares approximation. The Galerkin weak form of the incremental total Lagrangian formula for large deformation problems with the enforced essential boundary conditions using the penalty method is derived and then discretized in the complex variable meshless implementation. Five numerical examples are presented with detailed convergence study to demonstrate the accuracy of the proposed approach in dealing with non-conservative large deformation of the slender auxetic structures. [ABSTRACT FROM AUTHOR]

This paper aims to develop a theoretical model for a viscoelastic hard-magnetic elastomer membrane (HMEM) actuated by pressure and uniform magnetic field. The HMEM is initially a flat, circular film with a fixed boundary. The HMEM undergoes nonlinear large deformations in the transverse direction. The viscoelastic behaviors are characterized by using a rheological model composed of a spring in parallel with a Maxwell unit. The governing equations for magneto-visco-hyperelastic membrane under the axisymmetric large deformation are constructed. The Zeeman energy, which is related to the magnetization of the HMEM and the magnetic flux density, is employed. The governing equations are solved by the shooting method and the improved Euler method. Several numerical examples are implemented by varying the magnitude of the pre-stretch, pressure, and applied magnetic field. Under different magnetic fields, field variables such as latitudinal stress exhibit distinct curves in the radial direction. It is observed that these varying curves intersect at a point. The position of the intersection point is independent of the applied magnetic field and only controlled by pressure and pre-stretch. On the left side of the intersection point, the field variables increase as magnetic field strength increases. However, on the other side, this trend is reversed. During viscoelastic evolution, one can find that the magnetic field can be used to modulate the instability behaviors of the HMEM. These findings may provide valuable insights into the design of the hard-magnetic elastomer membrane structures and actuators. [ABSTRACT FROM AUTHOR]

Large deformation of sand due to soil liquefaction is a major cause for seismic damage. In this study, the mechanisms and modeling of large post-liquefaction deformation of sand considering the significant influence of water absorption in shearing and seismic wave conditions. Assessment of case histories from past earthquakes and review of existing studies highlight the importance of the two factors. Based on the micro and macro scale mechanisms for post-liquefaction shear deformation, the mechanism for water absorption in shearing after initial liquefaction is revealed. This is aided by novel designed constant water-absorption-rate shear tests. Water absorption in shearing can be classified into three types, including partial water absorption, complete water absorption, and compulsory water absorption. Under the influence of water absorption in shearing, even a strongly dilative sand under naturally drained conditions could experience instability and large shear deformation. The mechanism for amplification of post-liquefaction deformation under surface wave load is also explained via element tests and theoretical analysis. This shows that surface wave-shear wave coupling can induce asymmetrical force and resistance in sand, resulting in asymmetrical accumulation of deformation, which is amplified by liquefaction. A constitutive model, referred to as CycLiq, is formulated to capture the large deformation of sand considering water absorption in shearing and seismic wave conditions, along with its numerical implementation algorithm. The model is comprehensively calibrated based on various types of element tests and validated against centrifuge shaking table tests in the liquefaction experiments and analysis projects (LEAP). The model, along with various numerical analysis methods, is adopted in the successful simulation of water absorption in shearing and Rayleigh wave-shear wave coupling induced large liquefaction deformation. Furthermore, the model is applied to high-performance simulation for large-scale soil-structure interaction in liquefiable ground, including underground structures, dams, quay walls, and offshore wind turbines. [ABSTRACT FROM AUTHOR]

This study studies the deformation characteristics of the diversion tunnel of Jinping II Hydropower Station in order to guarantee the safety of the excavation of a large-section soft rock tunnel with a depth of 1000 m and increased ground stress. Using field data, theoretical computations, and numerical modeling, the proper reserved deformation of a deep soft rock tunnel is investigated, taking into consideration the size, in situ stress, and grade of the surrounding rock. The study reveals that (1) The diversion tunnel's incursion limit, which is typically between 20 and 60 cm, is serious; (2) The surrounding rock level > geostress > tunnel size are the influencing parameters of reserved deformation that remain unchanged while using the numerical simulation method, which is more accurate in simulating field conditions; (3) The west end of the Jinping diversion tunnel has a 30–60 cm reserved deformation range for the chlorite schist tunnel. The deformation law of a large-section, 1000 m-deep soft rock tunnel is better understood, and it also offers important references for high-stress soft rock tunnel engineering design, construction, and safety management. [ABSTRACT FROM AUTHOR]

Crawling robots have great potential in some harsh environments, but there are still some limitations, such as tiny structures that can only produce small deformation and poor load-carrying capacity. A lightweight inchworm-like crawling robot made of bistable structure driven by electrothermal actuation is proposed in this paper. The robot has the characteristics of large deformation and a certain extent of load capacity. The motion of the crawling robot was realized by the common effect of the bistable structure and the designed feet with anisotropic friction. The unstable transition process between snap-through and snap-back processes of the bistable structure was utilized to provide morphological deformation. Meanwhile the feet with anisotropic friction transformed the deformation to unidirectional movement of the crawling robot. Through electric experiments, the electrothermal driving influencing factors of bistable structure are tested, including heating time, maximum temperature and curvature change, which demonstrates the possibility of driving inchworm-like crawling robot with bistable structure and large-deformation. And the structure of the inchworm-like crawling robot assembled by a bistable shell pasted with an electric heating sheet and the designed feet with anisotropic friction. In order to evaluate the motion properties and load-carrying function of the inchworm-like crawling robot, the step length test under different voltages and the experiment of the crawling robot load-carrying capacity were completed. The results show that the crawling robot performs well in load-carrying, can achieve crawling movement under the condition of carrying 10 g and 20 g objects. The inchworm-like crawling robot provides a method to achieve large-deformation and load-carrying and demonstrates it is suitable in some extreme environments. [ABSTRACT FROM AUTHOR]

This paper aims to develop a nonrigid registration method of preoperative and intraoperative thoracoabdominal CT images in computer-assisted interventional surgeries for accurate tumor localization and tissue visualization enhancement. However, fine structure registration of complex thoracoabdominal organs and large deformation registration caused by respiratory motion is challenging. To deal with this problem, we propose a 3D multi-scale attention VoxelMorph (MA-VoxelMorph) registration network. To alleviate the large deformation problem, a multi-scale axial attention mechanism is utilized by using a residual dilated pyramid pooling for multi-scale feature extraction, and position-aware axial attention for long-distance dependencies between pixels capture. To further improve the large deformation and fine structure registration results, a multi-scale context channel attention mechanism is employed utilizing content information via adjacent encoding layers. Our method was evaluated on four public lung datasets (DIR-Lab dataset, Creatis dataset, Learn2Reg dataset, OASIS dataset) and a local dataset. Results proved that the proposed method achieved better registration performance than current state-of-the-art methods, especially in handling the registration of large deformations and fine structures. It also proved to be fast in 3D image registration, using about 1.5 s, and faster than most methods. Qualitative and quantitative assessments proved that the proposed MA-VoxelMorph has the potential to realize precise and fast tumor localization in clinical interventional surgeries. [ABSTRACT FROM AUTHOR]

The paper develops a systematic procedure for formulating finite elements on manifolds. The theoretical developments give rise to a modular computational framework for composing coordinate transformations and manifold parameterizations. The procedure is demonstrated with the Cosserat rod model furnishing a novel finite element formulation that rectifies the lack of objectivity of existing finite elements without violating the director constraints or compromising the symmetry of the tangent stiffness at equilibrium. The framework is element‐independent, allowing its implementation as a wrapper to existing element libraries without modification of the element state determination procedures. [ABSTRACT FROM AUTHOR]

This paper presents a modified relationship between small and large strain convergence by applying a small (residual) dilation angle, which behaves accurately for rock mass with the strain-softening behavior and complex dilatancy model. The modified relationship extends its applicability to a more general two- and three-dimensional excavation problems than previous study, irrespective of the constitutive behavior and rock dilatancy. On this basis, the longitudinal displacement profile (LDP) considering finite-strain is proposed, which can be corrected simply from the small strain analysis or obtained according to the actual parameters related to large deformation. The capability of the finite-strain LDP for estimating large convergences during tunnel advancement is verified by several comparisons with the existing numerical simulation and theoretical analysis results. The developed finite-strain LDP is promising to improve the convergence − confinement method when it applied to the rock-support interaction analysis in problems involving large deformation. The applicability of the displacement-release coefficient obtained from the small strain analysis for quantifying the stress relief to squeezing ground conditions is also investigated. Highlights: A relationship between small and large strain convergence is modified to accurately calculate large convergences from small strain analysis. Two equivalent formulas for the longitudinal displacement profile in squeezing ground considering finite strain are proposed. The applicability of displacement-release coefficient by small strain analysis for quantifying the stress relief to squeezing ground is obtained. [ABSTRACT FROM AUTHOR]

In this paper large deformation of the skew microplate made of laminated composite enhanced with graphene nanosheets is investigated using first shear deformation theory (FSDT) when the plate undergoes combination of mechanical and thermal loads. Halpin-Tsai model is utilised to model mechanical properties while for thermal properties Schapery model is considered. First, shear deformation of the plate was obtained while using Green-Lagrange tensor the non-linear strain of the microplate is extracted using the von-Karman assumptions. Then, by Modified Coupled Stress Theory (MCSD), the components of Cauchy and Couple stress tensors are specified. Finally, using Hamilton Principle the governing equation of the microplate and boundary conditions are computed. After deriving analytical governmental equation results are presented for the simple support boundary condition and the proposed model is validated by previously reported data and it proves to be promising. Primary results showed that with raising skew angle deflection and bending moment decreases which means microplate becomes more rigid in higher skew angles. Higher mechanical loads lead to higher deflections and bending moments. Four different configurations of the layers were analysed from which angle-ply configuration possessed highest deflection and bending while UD configuration revealed the lowest values of deflection and bending moment. [ABSTRACT FROM AUTHOR]

Climate warming accelerates permafrost thawing, causing warming‐driven disasters like ground collapse and retrogressive thaw slump (RTS). These phenomena, involving intricate multiphysics interactions, phase transitions, nonlinear mechanical responses, and fluid‐like deformations, and pose increasing risks to geo‐infrastructures in cold regions. This study develops a thermo‐hydro‐mechanical (THM) coupled single‐point three‐phase material point method (MPM) to simulate the time‐dependent phase transition and large deformation behavior arising from the thawing or freezing of ice/water in porous media. The mathematical framework is established based on the multiphase mixture theory in which the ice phase is treated as a solid constituent playing the role of skeleton together with soil grains. The additional strength due to ice cementation is characterized via an ice saturation‐dependent Mohr–Coulomb model. The coupled formulations are solved using a fractional‐step‐based semi‐implicit integration algorithm, which can offer both satisfactory numerical stability and computational efficiency when dealing with nearly incompressible fluids and extremely low permeability conditions in frozen porous media. Two hydro‐thermal coupling cases, that is, frozen inclusion thaw and Talik closure/opening, are first benchmarked to show the method can correctly simulate both conduction‐ and convection‐dominated thermal regimes in frozen porous systems. The fully THM responses are further validated by simulating a 1D thaw consolidation and a 2D rock freezing example. Good agreements with experimental results are achieved, and the impact of hydro‐thermal variations on the mechanical responses, including thaw settlement and frost heave, are successfully captured. Finally, the predictive capability of the multiphysics MPM framework in simulating thawing‐triggered large deformation and failure is demonstrated by modeling an RTS and the settlement of a strip footing on thawing ground. [ABSTRACT FROM AUTHOR]

Copyright of Southern Energy Construction is the property of Southern Energy Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Introduction] The construction process of pile insertion and removal for installing offshore wind turbines on mobile platforms is risky, which can easily affect the working performance of adjacent infrastructure, and even lead to its instability and failure. [Method] In order to clarify the mechanism of the influence of pile shoe insertion and removal on adjacent foundation, this paper used CEL large deformation method to simulate the insertion and removal process of similar rectangular pile shoe in homogeneous and heterogeneous clay, and focused on the analysis of the evolution mechanism of additional overturning angle caused by pile insertion process on adjacent jacket foundation; based on the simulation results of large deformation, the influence of soil softening effect on the ultimate bearing capacity of adjacent buckets after pile shoe removal was further studied by using small deformation. [Result] The results show that under the action of pile shoe compaction, the rotational displacement of the three-cylinder jacket foundation will take place, and it will decrease gradually with the increase of net spacing. At the same time, the soil softening caused by compaction will reduce the bearing capacity of adjacent cylinder. [Conclusion] The overturning angle of three-cylinder jacket in heterogeneous soil is larger and the corresponding penetration depth is deeper due to the influence of pile shoe insertion and removal. The affected area of softening area caused by pile shoe insertion and removal is larger in horizontal direction and smaller in depth direction in homogeneous clay. In homogeneous clay, the average strength loss is small, and the horizontal and angular bearing capacity loss of the three-cylinder jacket is small. In homogeneous and heterogeneous clays, the vertical bearing capacity is reduced obviously, and the maximum reduction factor can reach 0.72.

Ultra-long thin-walled deployable composite structures with high-strain ability are of considerable interest and increasingly used in large-size deployable spacecraft structures due to their high folding-storage ratio function. This paper seeks to investigate continuous curing technology of an ultra-long thin-walled Lenticular Deployable Composite Boom (LDCB) made of high strain carbon-fiber-reinforced-plastics. The equipment for continuous curing of thin-walled boom is designed. The continuous forming process including flattening, traction and coiling are simulated by explicit finite element method for determining the length of the transition zone of the equipment, the gap of the flattening roll, and the radius of the reeling roller. [ABSTRACT FROM AUTHOR]

Due to geological processes such as sedimentation, tectonic movement, and backfilling, natural soil often exhibits characteristics of rotated anisotropy. Recent studies have shown the significant impact of rotated anisotropy on slope stability. However, little research has explored how this rotated anisotropy affects the large deformations occurring after slope failure. Therefore, this study integrates rotated random field theory with smoothed particle hydrodynamics (SPH) to investigate its influence on post‐failure slope behavior. Focusing on a typical slope scenario, this research utilizes graphics processing unit (GPU)–accelerated covariance matrix decomposition (CMD) method to create rotated anisotropy random fields and applies the SPH framework for analysis. It examines the influence of rotated anisotropy angles and the cross‐correlation between cohesion and internal friction angle on landslides. The results indicate that the rotational anisotropy of the slope significantly influences post‐failure behavior. When the rotation angle is close to the slope surface, it tends to amplify both the magnitude and variability of slope failure. Furthermore, the study evaluates the efficiency of generating these random fields and emphasizes the substantial computational speed improvements achieved with GPU acceleration. These findings offer a robust approach for probabilistic analysis of slope large deformations considering rotated anisotropy. They provide a theoretical foundation for accurately assessing the risk of slope collapse, holding significant practical implications for geotechnical engineering. [ABSTRACT FROM AUTHOR]

Seepage‐induced backward erosion is a complex and significant issue in geotechnical engineering that threatens the stability of infrastructure. Numerical prediction of the full development of backward erosion, pipe formation and induced failure remains challenging. For the first time, this study addresses this issue by modifying a recently developed five‐phase smoothed particle hydrodynamics (SPH) erosion framework. Full development of backward erosion was subsequently analysed in a rigid flume test and a field‐scale backward erosion‐induced levee failure test. The seepage and erosion analysis provided results consistent with experimental data, including pore water pressure evolution, pipe length and water flux at the exit, demonstrating the good performance of the proposed numerical approach. Key factors influencing backward erosion, such as anisotropic flow and critical hydraulic gradient, are also investigated through a parametric study conducted with the rigid flume test. The results provide a better understanding of the mechanism of backward erosion, pipe formation and the induced post‐failure process. [ABSTRACT FROM AUTHOR]

The applications of piezoelectric materials in the field of smart structures have received significant attention from both the communities of science and engineering. Numerous experimental studies have been carried out to endow smart structures with good flexibility. The flexible/stretchable piezoelectric materials are developed to fit this emerging trend. Generally, these materials undergo significant deformation before reaching fracture failure, and they often exhibit a stress-softening phenomenon during the deformation process. However, the traditional linear constitutive model, typically used for rigid piezoelectric ceramics, continues to dominate theoretical and modeling processes in many scenarios. Existing nonlinear constitutive models usually introduce additional coefficients besides elastic, piezoelectric, and dielectric coefficients. Determining these coefficients requires a substantial number of experiments. In this work, based on a Neo-Hookean material model and electromechanical theory, a novel model for flexible piezoelectric material considering large deformation has been established. In contrast with existing models, the present model describes the nonlinear behavior of flexible piezoelectric material without the need for introducing additional parameters. Furthermore, this model exhibits a quadratic dependence of stress on the electric field. To facilitate practical applications, the constitutive model has been implemented using the commercial simulation software ABAQUS through a user subroutine. The accuracy of the subroutine is validated by comparing simulations with analytical solutions for uniaxial stretching of a flexible piezoelectric ribbon. Several numerical examples are followed to demonstrate the robustness of the elements. The proposed model offers a valuable tool for the analysis and design of flexible piezoelectric material. [ABSTRACT FROM AUTHOR]

The traditional viscoelastic-plastic constitutive model of asphalt mixture is mostly suitable for the case of small deformation at room temperature, which may have difficulties in the evaluation of the large plastic deformation during the compaction process. In order to evaluate the viscoelastic-plastic rheological characteristics of hot-mix asphalt (HMA) during construction compaction, in this research, the Bodner–Partom (BP) model was revised by considering the strain after the total strain minus the instantaneous elastic strain, and the viscoelastic rheological parameters of the revised BP model were obtained through uniaxial compression creep tests. Also, the creep behavior of the BP model was verified through numerical simulation of the finite-element method. The results found that in the initial creep stage, with the increase of initial compaction density, the instantaneous deformation decreased, and the deformation recovery rate increased after unloading. Correspondingly, the pure viscosity parameter (η) increased, the hardening constant of the load (Z) increased, and the limit value (D0) decreased, indicating that the viscous properties of HMA were enhanced, and the plastic and viscoplastic strain rates decreased. In the stable creep stage, the strain value was the largest under the initial loading. As the number of cycles increased, the HMA strain rate decreased and tended to be stable, and the compaction was basically formed. Correspondingly, η gradually increased, Z increased, and the plastic and viscoplastic strain rates decreased. D0 decreased first and then tended to be stable, indicating that the proportion of plastic deformation of single cycle load to total deformation gradually decreased and tended to be stable. With the increase of initial compaction density, the plastic strain of the same loading cycle decreased first and then tended to be consistent. Finally, it was found that the simulated calculation curve further verified the rationality of the BP model. The relevant results can lay a theoretical foundation for analyzing the rheological mechanical properties of HMA in the construction stage. [ABSTRACT FROM AUTHOR]

A new elasto-plastic thin shell finite element of the absolute nodal coordinate formulation is proposed to improve the computation efficiency for the shell structure undergoing both large deformations and finite rotations based on the Kirchhoff–Love theory and stress resultant method. The Ilyushin–Shapiro plastic model with linear isotropic hardening is adopted to develop the plastic formulation of a shell element. The model is formulated directly in terms of stress resultants, and thus the through-thickness integration associated with the classical method is entirely removed. In particular, a modified approach is proposed to solve the problem associated with inaccurate hardening modulus. The corresponding return-mapping algorithm is shown to update the values of stress, and a strategy is introduced to choose the active yielding surfaces in the algorithm. Furthermore, the Jacobian of internal forces is deduced via deriving the consistent elasto-plastic tangent moduli. The arc-length method is used to accurately track the load–displacement equilibrium path in the buckling analysis of an elasto-plastic thin shell. The dynamics of the thin shell is also studied by using the generalized-alpha algorithm. Several numerical examples are presented to verify the accuracy and efficiency of the proposed formulation. [ABSTRACT FROM AUTHOR]

Abstract NPR anchor cable is a new type of support material with negative Poisson's ratio effect, which is widely used in mine support because of its superb compensating mechanical effect. In order to study more deeply the support effect of NPR anchor cable in soft rock large deformation tunnel, indoor test, numerical simulation and field monitoring were used to study the strong weathering carbonaceous slate tunnel in Min County. The study shows that NPR anchor cable has extraordinary compensating mechanical behavior for soft rock large deformation tunnel, which can control the deformation of tunnel surrounding rock below 300 mm and keep the constant resistance value around 350 kN, which has obvious effect on the control of broken rock. To provide a basis for other research on support for large deformation tunnels in soft rock.

The material point method (MPM) has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation. In this paper, we survey the current state-of-the-art in the MPM simulation of hydro-mechanical behaviour in two-phase porous geomaterials. The review covers the recent advances and developments in the MPM and their extensions to capture the coupled hydro-mechanical problems involving large deformations. The focus of this review is aiming at providing a clear picture of what has or has not been developed or implemented for simulating two-phase coupled large deformation problems, which will provide some direct reference for both practitioners and researchers.

The collapse of the tunnel face is a prevalent geological disaster in tunnelling. This study employs a three-dimensional (3D) material point method (MPM) to simulate the dynamic collapse process and post-failure mechanisms of the tunnel face. The specific focus is on the scenario where the auxiliary air pressure balanced shield with a partially filled chamber is shut down. To assess the suitability of the 3D MPM, numerical solutions are compared with the results from small-scale experimental tests. Subsequently, a series of large-scale numerical simulations is conducted to explore the dynamic collapse characteristics of the tunnel face induced by the shutdown of the EPB shield under various support air pressures and cutter head conditions. The temporal evolution of the accumulated soil masses in the soil chamber and ground responses under different support air pressures, cutter head types and opening ratios are discussed. In particular, the associated surface subsidence due to the tunnel face collapse is determined and compared with empirical solutions. Numerical results confirm the applicability of the 3D MPM for simulating the large-scale tunnel face collapse scenarios, spanning from small to large deformation analysis.

Accurately simulating the deployment process of coupled systems in deep-sea environments remains a significant challenge. This study employs the Absolute Nodal Coordinate Formulation (ANCF) to dynamically model and analyze multi-body systems based on the Pendant Installation Method (PIM). Utilizing the principle of energy conversion, this study calculates the stiffness, generalized elastic forces, mass matrices, and Morison equation, formulating a motion equation for the dynamic coupling of nonlinear time-domain forces in cables during pendulum deployment, which is numerically solved using the implicit generalized-α method. By comparing the simulation results of this model with those from the catenary theory model, the advanced modeling capabilities of this model are validated. Lastly, the sensitivity of the multi-body system under various boundary conditions is analyzed. The results indicate that deployment operations are more effective in environments with strong ocean currents. Furthermore, upon comparing the impacts of structural mass and deployment depth on the system, it was found that deployment depth has a more significant effect. Consequently, the findings of this study provide a scientific basis for formulating subsequent optimization strategies. [ABSTRACT FROM AUTHOR]

NPR anchor cable is a new type of support material with negative Poisson's ratio effect, which is widely used in mine support because of its superb compensating mechanical effect. In order to study more deeply the support effect of NPR anchor cable in soft rock large deformation tunnel, indoor test, numerical simulation and field monitoring were used to study the strong weathering carbonaceous slate tunnel in Min County. The study shows that NPR anchor cable has extraordinary compensating mechanical behavior for soft rock large deformation tunnel, which can control the deformation of tunnel surrounding rock below 300 mm and keep the constant resistance value around 350 kN, which has obvious effect on the control of broken rock. To provide a basis for other research on support for large deformation tunnels in soft rock. Highlights: The large deformation tunnel in soft rock was studied by laboratory experiment, numerical simulation and field monitoring. The NPR anchor cable with negative Poisson's ratio effect is used to support the soft rock tunnel with large deformation in the western transverse mountain area, and the compensating mechanical properties of the NPR anchor cable are verified. [ABSTRACT FROM AUTHOR]

The Smoothed Particle Finite Element Method (SPFEM) has gained popularity as an effective numerical method for modelling geotechnical problems involving large deformations. To promote the research and application of SPFEM in geotechnical engineering, we present ESPFEM2D, an open-source two-dimensional SPFEM solver developed using MATLAB. ESPFEM2D discretizes the problem domain into computable particle clouds and generates the finite element mesh using Delaunay triangulation and the α -shape technique to resolve mesh distortion issues. Additionally, it incorporates a nodal integration technique based on strain smoothing, effectively eliminating defects associated with the state variable mapping after remeshing. Furthermore, the solver adopts a simple yet robust approach to prevent the rank-deficiency problem due to under-integration by using only nodes as integration points. The Drucker-Prager model is adopted to describe the soil's constitutive behavior as a demonstration. Implemented in MATLAB, this open-source solver ensures easy accessibility and readability for researchers interested in utilizing SPFEM. ESPFEM2D can be easily extended and effectively coupled with other existing codes, enabling its application to simulate a wide range of large geomechanical deformation problems. Through rigorous validation using four numerical examples, namely the oscillation of an elastic cantilever beam, non-cohesive soil collapse, cohesive soil collapse, and slope stability analysis, the accuracy, effectiveness and stability of this open-source solver have been thoroughly confirmed. [ABSTRACT FROM AUTHOR]

Energy drives the large deformation of soft rock tunnels, which is a nonlinear mechanical behavior of surrounding rock. This study aims to develop an analytical model for analyzing the energy conversion and absorption processes involved in tunneling. First, an analytical approach is presented for analyzing the energy conversion of the surrounding rock and energy absorption properties of the yielding support system during tunnel excavation. Subsequently, a comprehensive parametric investigation is conducted using the analytical model to investigate the impact of support pressure, tunnel radius, and initial stress on the energy conversion and dissipation of the surrounding rock. Similarly, the effect of support installation time, tunnel radius, and initial stress on the energy absorption properties of the yielding support system is explored. The results reveal that energy is input into the surrounding rock at the outer boundary through radial stress work. A portion of the energy is converted into elastic strain energy of the surrounding rock. Simultaneously, the plastic deformation of the surrounding rock consumes some of the input energy. Subsequently, the remaining energy flows from the excavation boundary as rock pressure work. Installing yielding components in the support system significantly enhances its maximum energy absorption capacity, which may be raised by up to 30 times. Moreover, the earlier the support installation time, the larger the tunnel radius, and the higher the initial stress, the more energy the yielding elements of the support system absorb. Highlights: Proposed an analytical model to characterize energy conversion in large deformation tunnels with yielding support. Quantitatively analyzed the energy conversion and dissipation properties in the surrounding rock. Explored the energy absorption characteristics of yielding support in large deformation tunnels. [ABSTRACT FROM AUTHOR]

To address the large deformation of a layered soft rock tunnel, the Muzhailing Tunnel was selected as the research subject, and an anchor cable made of Negative Poisson's ratio steel (NPR anchor cable) was used for the tunnel support. A combined approach of laboratory experiments, numerical simulations, and field tests was utilized to analyze the deformation mechanisms of layered carbonaceous shale under high ground stress, and a support scheme with an NPR steel anchor cable was proposed. The mechanical properties of the NPR anchor cable were studied using laboratory static tensile tests. The results indicated that NPR anchor cables exhibit constant tension and uniform stretching during the stretching process, with no apparent necking phenomenon upon fracture. By establishing a DFN-DEM tunnel numerical model and simulating the deformation progression of surrounding rocks with varying joint dip angles, the large deformation mechanism of rock bending and shear slip in the Muzhailing Tunnel was elucidated. The field application tests of the NPR anchor cable validated its efficacy in controlling large deformations of the rock mass, providing new support materials and methods for large deformation support in soft rock tunnels. [ABSTRACT FROM AUTHOR]

Shape sensing refers to the deformation reconstruction of structures using measured surface strain. However, there is currently a lack of research on the shape sensing of large deformations, especially for beam structures. To address this issue, this paper proposes a new method called the rotation angle approximation (RAA) for reconstructing large deformations of beam structures. This method utilizes theoretical and actual curvatures to create a least-squares error functional. By minimizing this functional, the rotation angles of the corresponding beam can be obtained, avoiding the accumulation of errors that occurs when using traditional computation methods. The deformed shapes can be predicted utilizing the boundary conditions and the rotation angles along the beam. This method can reconstruct the large deformation of a beam without requiring prior knowledge about the material properties or external loads. The accuracy and effectiveness of this method were validated through numerical simulations and experiments. The results indicate that this method can accurately predict the different deformations of a beam induced by various loading conditions. [ABSTRACT FROM AUTHOR]

In this study, we propose an explicit topology optimization approach for multi-material composite structures that considers both geometric and material nonlinearities. Our method identifies each material using moving morphable components, resulting in explicit geometric descriptions and fewer design variables. In finite-element analysis, redundant degrees of freedom are removed to prevent highly distorted elements and improve computational efficiency. A numerical example demonstrated the methodology’s validity and the importance of accounting for geometric and material nonlinearities when designing a multi-material structure. We also show that, even with the same objective function and structural volume, the optimal usage ratio of the constituent materials varies depending on the problem. Using the proposed method, optimized structures with superior performance that cannot be achieved with a single material can be obtained. [ABSTRACT FROM AUTHOR]

Image registration is a fundamental task in various applications of medical image analysis and plays a crucial role in auxiliary diagnosis, treatment, and surgical navigation. However, cardiac image registration is challenging due to the large non-rigid deformation of the heart and the complex anatomical structure. To address this challenge, this paper proposes an independently trained multi-scale registration network based on an image pyramid. By down-sampling the original input image multiple times, we can construct image pyramid pairs, and design a multi-scale registration network using image pyramid pairs of different resolutions as the training set. Using image pairs of different resolutions, train each registration network independently to extract image features from the image pairs at different resolutions. During the testing stage, the large deformation registration is decomposed into a multi-scale registration process. The deformation fields of different resolutions are fused by a step-by-step deformation method, thereby addressing the challenge of directly handling large deformations. Experiments were conducted on the open cardiac dataset ACDC (Automated Cardiac Diagnosis Challenge); the proposed method achieved an average Dice score of 0.828 in the experimental results. Through comparative experiments, it has been demonstrated that the proposed method effectively addressed the challenge of heart image registration and achieved superior registration results for cardiac images. [ABSTRACT FROM AUTHOR]

The objective of this classroom note is to propose a generalized model for a compressible elastically isotropic material with elastic-inelastic response. The model is generalized for an exponential Fung-type strain energy with a sum of new higher order elastic distortional deformation invariants that can model elastic-inelastic distortional deformation. In contrast with an Ogden-type model, the coefficients of the proposed higher order invariants do not affect the small deformation response. Moreover, there is no need to determine eigenvalues and eigenvectors of the elastic distortional deformation tensor. Examples show that the equations can model preconditioning of biological tissues as well as elastic instability. [ABSTRACT FROM AUTHOR]

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Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research is concerned with the thermal bending and stability of temperature-dependent nanocomposite curved pipes strengthened with carbon nanotubes (CNTs) subjected to uniform temperature rise. Thermo-mechanical characteristics of the polymer composite pipe are assumed to vary entirely in the thickness by a non-uniform function of the radius. Five different patterns are selected to model the propagation profile of CNTs amongst the pipe thickness. Based on the shear deformation and von-Karman kinematic hypothesis, nonlinear balance equations of the polymer curved pipe are determined via varying the total potential energy of the system. Governing equations as a set of coupled nonlinear differential equations are analytically solved using a perturbation-based technique. Closed-form solutions are derived to estimate large-amplitude deflection of nanocomposite curved pipes with pinned and clamped boundaries under uniform thermal loading. The obtained results show the influences of important parameters such as material/geometrical characteristics and foundation stiffness on the thermally induced nonlinear response of polymer nanocomposite curved pipes. [ABSTRACT FROM AUTHOR]

This study presents a semi‐implicit MPM to adequately characterize the mechanical behavior of unsaturated soil based on Biot's mixture theory. To represent the dependency of the degree of saturation on the suction, we employ the VG model along with a soil‐water characteristic curve, which determines a functional form of permeability called the Mualem model. Hencky's hyperelastic model and the Drucker‐Prager model assuming nonassociativity are adopted for elastic and plastic deformations, respectively. The novelty of this study is the incorporation of the fractional‐step method into the MPM framework so that the pore water pressure is obtained by implicitly solving the pressure Poisson's equation, which reduces numerical instability and improves computational efficiency. Also, because the drag force between solid and liquid phases is evaluated using the intermediate velocity of pore water relative to the intermediate velocity of solid skeleton, the time increment can be chosen without considering the magnitude of water permeability. In addition, to suppress "odd‐even" oscillation, we employ a sub‐grid method in which two grids with different spatial resolutions are used for the velocities and pore water pressure. Furthermore, considering the advantages and disadvantages of two different interpolation schemes for pore water pressure, we suggest switching the schemes depending on the model conditions. Several numerical examples are presented to demonstrate the performance of the proposed method. Specifically, unidirectional consolidation and leak flow analyses are performed for verification purposes, followed by validation analysis of a model experiment of infiltration‐induced landslides. [ABSTRACT FROM AUTHOR]

The first and fully validated smoothed particle hydrodynamics (SPH) model is presented to tackle coupled flow–deformation problems in unsaturated porous media that undergo large deformation and post-failure behaviour. Unlike the commonly adopted double-layer SPH framework for saturated soils, this paper presents a three-phase single-layer SPH model capable of predicting anisotropic seepage flows through porous media and their complete time-dependent transition from unsaturated to saturated states, as well as their influence on the mechanical behaviour of the porous media and vice versa. The mathematical framework is developed based on Biot's mixture theory and discretised using the authors' recently developed novel SPH approximation scheme for the second derivatives of a field quantity. The soil is modelled using a suction-dependent elastoplastic constitutive model, expressed in terms of effective stress and suction. In addition, an adaptive two-timescale scheme is proposed for the first time to address existing challenges in solving coupled-flow large-deformation problems that involve a significant difference in the timescale required for the solid and fluid phases. The capability of the proposed SPH model was demonstrated through fundamental consolidation tests and a large-scale rainfall-induced slope failure experiment. Very good agreements with theoretical solutions and experimental results are achieved, suggesting that the proposed SPH model can be readily extended to solve a wide range of large-scale geotechnical applications involving coupled unsaturated seepage–deformation problems. [ABSTRACT FROM AUTHOR]

Soft actuators with embedded fluidic channels are promising for soft robotics, but their continuous nature presents challenges in accurate and efficient modeling. Existing studies on dynamic behavior have shown that both approximate and exact methods have limitations in accurately predicting the deflection of soft actuators. Additionally, conventional methods require experimental parameter extraction for each individual actuator. To address these challenges, we propose a modified analytical method and use finite element analysis as the defined correction functions to improve accuracy and computational efficiency, providing a promising tool for the design and control of soft robotic systems. In this work, we propose a solution methodology for simulating the dynamic behavior of fluidic soft actuators, which are widely used in soft robotics applications. Our approach takes into account the cross-sectional geometry and the number of channels in the actuator's configuration. By scrutinizing various fluidic actuation designs, we can deduce the most suitable cross-sectional configuration for optimal performance. Compared to existing analytical methods, our approach is more accurate and does not require additional calculation time. As the method is adaptable with experimental models, it can be used to design and optimize soft actuators while can be refined and improved through experimental model updating. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The material point method (MPM) is often applied to large deformation problems that involve sharp gradients in the solution field. Representative examples in geomechanics are interactions between soils and various "structures" such as foundations, penetrometers, and machines, where the displacement fields exhibit sharp gradients around the soil‐structure interfaces. Such sharp gradients should be captured properly in the MPM discretization to ensure that the numerical solution is sufficiently accurate. In the MPM literature, several types of locally refined discretizations have been developed and used for this purpose. However, these local refinement schemes are not only quite complicated but also restricted to certain types of basis functions or update schemes. In this work, we propose a new MPM formulation, called the mapped MPM, that can efficiently capture sharp gradients with a uniform background grid compatible with every standard MPM basis function and scheme. The mapped MPM is built on the method of auxiliary mapping that reparameterizes the given problem in a different domain whereby sharp gradients become much smoother. Because the reparameterized problem is free of undesirably sharp gradients, it can be well solved with the standard MPM ingredients including a uniform background grid. We verify and demonstrate the mapped MPM through several numerical examples, with particular attention to soil‐structure interaction problems. [ABSTRACT FROM AUTHOR]

Characteristics of stress‐dependent properties of rocks are commonly described by empirical laws. It is crucial to establish a universal law that connects rock properties with stress. The present study focuses on exploring the correlations among permeability, porosity, and compressibility observed in experiments. To achieve this, we propose a novel finite strain‐based dual‐component (FS‐DC) model, grounded in the finite strain theory within the framework of continuum mechanics. The FS‐DC model decomposes the original problem into the rock matrix and micro‐pores/cracks components. The deformation gradient tensor is utilized to derive the constitutive relations. One of the novelties is that the stress‐dependent variables are calculated in the current configuration, in contrast to the reference configuration used in small deformation theory. The model has only a few number of parameters, each with specific physical interpretations. It can be reduced to existing models with appropriate simplifications. Then, model performance is examined against experimental data, including permeability, porosity, compressibility, volumetric strain and specific storage. It proves that the variations of these properties are effectively described by the proposed model. Further analysis reveals the effect of pores/cracks parameters. The validity of the FS‐DC model is examined across a broad range of pressures. The results show that rock properties at high confining pressures (>$>$300 MPa) differ from those observed under relatively low pressures (<$<$200 MPa). This disparity can be attributed to inelastic behaviors of micro‐structure, wherein the rock skeleton undergoes permanent deformation and breakage. [ABSTRACT FROM AUTHOR]

Landslides represent one of the most frequent and destructive natural hazards in recent years. In highly seismic countries, the occurrence of large earthquakes is a significant triggering factor in the generation of these landslides. Therefore, it is of interest to various disciplines within civil engineering to study these phenomena through empirical analysis, analytical methods, and numerical modelling, aiming to provide a more accurate representation of these complex phenomena. For this purpose, a computational modelling approach is developed to describe the dynamics of a landslide or rockslide induced by seismic loading, using the Material Point Method (MPM). Presently, the utilization of MPM holds considerable significance because it is a numerical method engineered to simulate large deformations. This stands in contrast to conventional methods like the Finite Element Method (FEM), which struggles to precisely deal with this type of problems due to the generation of errors related to mesh distortion. In this study, it is performed a modelling process involving a real and documented scenario--a massive landslide occurrence in the vicinity of Daguangbao, China, triggered by the 2008 Wenchuan Earthquake. The obtained results successfully capture the landslide dynamics in terms of velocities, deformations, and travel distances in accordance with existing reports and other research endeavours. The maximum attained velocities of the landslide are approximately 100 km/h, affirming the catastrophic nature of this event. [ABSTRACT FROM AUTHOR]

Torpedo anchor is one offshore anchoring which has been gaining popularity recently for floating structures. The torpedo anchor was expected to resist the environmental loading transferred from the floating platform. Thus, the understanding of the holding capacity of torpedo anchors under vertical and horizontal combined loading is the key concern of its design. Nonetheless, most of the previous studies are deterministic without considering the common existing random heterogeneity nature of marine soil. In light of this situation, this paper reports a large deformation random finite element study under the framework of the Monte Carlo method. VH failure envelopes of torpedo anchors in heterogeneous soil were obtained by conducting simulations of continuous extraction procedures along different directions. Furthermore, the strain-softening behaviour of the soil was also accounted for considering the server deformation of the soil. The results show that both the size and shape of the VH failure envelope are significantly affected by random heterogeneity of soil. A series of VH failure envelopes of various probabilities of failure was thus given to guide the design. Results in this paper may be constructive for the safety design of the torpedo anchor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The prevention and control of deformation and instability in high-stress soft rock roadways hold significant value for ensuring normal mine production and the safety of personnel and equipment. This study focuses on the pedestrian descent from the 11th mining area of the Yindonggou Mine, providing a thorough elucidation of the internal mechanisms leading to large deformation and instability in the roadway. It accounts for the influences of surrounding rock lithology, geological structure, and support measures. Consequently, based on the theory of rock instability, corresponding tunnel repair measures and control strategies were proposed and verified through field application. The results indicate that: (1) High strength dispersion and insufficient support resistance of the expansive weak and fractured surrounding rock sections are critical factors inducing significant deformation in the soft rock roadway of Yindonggou Mine. (2) The primary factor contributing to the large deformation disaster in the Yindonggou Mine roadway is the disturbance caused by proximate coal seam mining, which exacerbates the conflict between the high structural stress in the strata and the low strength of the surrounding rock. High-level stress initially leads to deformation in the weakly supported floor, followed by deformation and instability of the surrounding rock, ultimately culminating in the collapse of the entire roadway section. (3) Soft rock support should be designed with varying schemes tailored to the rock type and structural stress of the surrounding rock in the tunnel. For tunnels with carbon mudstone and expansive soft rock as the main roof and floor components, the support plan should primarily focus on enhancing the support stiffness of the tunnel wall. Conversely, for tunnels where sandstone predominates as the roof and floor material, the support plan should aim to restore the three-dimensional stress state of the surrounding rock and fully utilize its self-supporting capacity. (4) Based on the engineering conditions of pedestrian downhill in No.11 mining area of Yindonggou Mine, a differentiated support scheme is proposed. The feasibility and effectiveness of each support scheme are verified by numerical simulation, so as to provide valuable reference and enlightenment for similar projects.