Accumulative Deformation Research Articles

Effect of reinforcement layer on dynamic wetting behavior and accumulative deformation of granite residual soil subgrade

This paper contributes to investigate the impact of reinforcement layer on the dynamic wetting behavior and accumulative deformation of granite residual soil subgrade of expressways in southern China. The wetting test combined with vehicle test and vibration test were conducted in two selected test sections with a reinforcement layer (WRL) and without a reinforcement layer (NRL), respectively. The influence of vehicle speed, moving load, repeated loading, and loading number on the dynamic stress, dynamic acceleration, and dynamic displacement of both the NRL and WRL subgrades was explored under different wetting conditions. The impact of the wetting number and traffic loading on the time-domain characteristics of the dynamic response and the accumulative deformation were revealed. The results indicate that the WRL subgrade can effectively reduce the dynamic response compared to the NRL subgrade. The influence depth of the WRL subgrades is 1.3 m, while the influence depth of the NRL subgrades is 3.3 m. Dynamic stress, dynamic acceleration, and dynamic displacement increase with increasing the wetting number, moving load, and repeated loading. The peak values of the dynamic stress and dynamic acceleration time-domain curves for the NRL subgrade are 27 % and 24 % higher than those of the WRL subgrade, respectively. At 3 million loading numbers, the accumulative deformation of the NRL subgrades is 53.7 % higher than that of the WRL subgrade. The dynamic stress, dynamic acceleration, and dynamic displacement of the NRL subgrade are generally higher than those of the WRL subgrade. The predictive models are established to correlate the wetting, dynamic load, and the dynamic response for both NRL and WRL subgrades. The dynamic stress, dynamic acceleration, and dynamic displacement measured in the vibration test are generally higher than those measured in the vehicle test. The research results provide a reference for the design of durability subgrade in granite residual soil regions.

Investigation of Soil Arching Effect and Accumulative Deformation in Pile-Supported Embankments Subjected to Traffic Loading Using Numerical Modeling

Investigation of Soil Arching Effect and Accumulative Deformation in Pile-Supported Embankments Subjected to Traffic Loading Using Numerical Modeling

Coupling effect of freezing-thawing cycles and dynamic loading on the accumulative deformation and microstructure of foam concrete

Coupling effect of freezing-thawing cycles and dynamic loading on the accumulative deformation and microstructure of foam concrete

Modeling of fatigue behaviors of rock materials subjected to cyclic loads with fractional-order plastic flow rule

Compressive cyclic loads induce a progressive failure in rock materials, and the long-term stability can not be guaranteed by the strength under monotonic load. To this end, the present study aims at establishing an elastoplastic fractional fatigue damage model for predicting the accumulative deformation of rock materials in a unified framework. A fractional-order plastic flow rule is introduced to describe volume transformation of rock sample from compression to expansion, eliminating the need for plastic potential functions. And a hardening function with an equivalent plastic shear strain is adopted. Concerning the fatigue effects, the progressive deterioration of material due to cyclic loads is intricately linked to microstructural degradation, depicted by a convolution law. In the context of creep deformation, loading cycle serves as an equivalent time measure, connecting the plastic deformation with the fatigue damage. In order to verify the accuracy, the proposed model is numerically implemented by a returning mapping procedure simulate the mechanical responses of three types of rocks in both uniaxial and triaxial cyclic tests. Comparative analysis with associated fatigue model is also provided to evaluate the accumulative deformation and damage evolution of concerned rocks.

Deformation Characteristics and Activation Dynamics of the Xiaomojiu Landslide in the Upper Jinsha River Basin Revealed by Multi-Track InSAR Analysis

The upper Jinsha River, located in a high-mountain gorge with complex geological features, is highly prone to large-scale landslides, which could result in the formation of dammed lakes. Analyzing the movement characteristics of the typical Xiaomojiu landslide in this area contributes to a better understanding of the dynamics of landslides in the region, which is of great significance for landslide risk prediction and analysis. True displacement data on the surface of landslides are crucial for understanding the morphological changes in landslides, providing fundamental parameters for dynamic analysis and risk assessment. This study proposes a method for calculating the actual deformation of landslide bodies based on multi-track Interferometric Synthetic Aperture Radar (InSAR) deformation data. It iteratively solves for the optimal true deformation vector of the landslide on a per-pixel basis under a least-squares constraint based on the assumption of consistent displacement direction among adjacent points on the landslide surface. Using multi-track Sentinel data from 2017 to 2023, the line of sight (LOS) accumulative de-formation of the Xiaomojiu landslide was obtained, with a maximum LOS deformation of −126 mm/year. The true surface displacement of the Xiaomojiu landslide after activation was calculated using LOS deformation. The development of two rotational sub-slipping zones on the landslide body is inferred based on the distribution of actual displacements along the central profile line. Analysis of temporal changes in water body area data revealed that the Xiaomojiu landslide was activated after a barrier lake event and continuously moved due to the influence of higher water levels’ in the river channel. In conclusion, the proposed method can be applied to calculate the true surface displacement of landslides with complex mechanisms for analyzing the movement status of landslide bodies. Furthermore, the spatiotemporal analysis of the Xiaomojiu landslide characteristics can support analyzing the mechanisms of similar landslides in the Jinsha River Basin.

Behaviours of geogrid-reinforced asphalt pavement over a localized void under cyclic loading

A set of large-scale physical model tests were performed to investigate the performance of unreinforced and glass fibre geogrid-reinforced asphalt pavement under the development of a void in the subgrade. Traffic loadings were simulated with repeated sinusoidal loadings of different amplitudes. The formation of the void was simulated using a novel displacement control device between loading cycles. The accumulative permanent deformation of the asphalt pavement, the composite resilient modulus and dissipated energy were presented and analysed. It was found that the inclusion of geogrid greatly improved the fatigue life of asphalt pavement, and the stronger the geogrid, the greater the improvement if a void was formed below the asphalt layer. After forming the void, the composite moduli of the pavements increased compared with that during the first cyclic loading stage (without the void) and seemed to be not much affected by the geogrid type. The effect of cyclic loading level on the composite modulus was not significant. The inclusion of geogrid in asphalt had a limited effect on the dissipated energy in the pavements with and without voids. The dissipated energy increased with the cyclic loading amplitude.

Effect of accumulative hot rolling on the microstructure and mechanical properties of dual-phase titanium alloy consolidated via SPS sintering

The improvement of microstructure and mechanical properties of Ti alloys is of great significance for their industrial application. In this study, a developed multi-step hot deformation process was employed to regulate the grain boundaries (GBs), hetero-phase boundaries (PBs) and dislocation structure for dual-phase titanium alloy. The effects of accumulative thermal deformation ratios from 33% to 75% (2–8 cycles) on the microstructure and mechanical properties have been investigated. It is found that the sintered sample shows a typical Widmanstätten structure without obvious pores and micro-cracks. However, with the increase of the deformation ratio, for the hexagonal close packed (HCP) Ti, the crystal orientations of {011‾0} and {1‾21‾0} were gradually transformed into {0001}, with the change of high-angle grain boundaries (HAGBs) to low-angle grain boundaries (LAGBs). The density of stored geometrically necessary dislocations (GNDs) density raised dramatically from 1.95 × 1014 m−2 to 6.5 × 1014 m−2, and various types of dislocations have been characterized. For the β phase, in the thermal deformation process, high density α-precipitates with an average thickness below 20 nm had formed with Burgers relationship of {110}BCC//{0001}HCP and <1‾11 >BCC//<21‾1‾0 >HCP. Finally, the yield strength of the dual-phase titanium alloy increased dramatically from 881 MPa to 1178 MPa, and the ductility can still maintain at above 8.5%. The enhanced strength was mainly contributed by the increase of geometrically necessary boundaries (GNBs) and nano-lamellae boundaries (NLBs). Therefore, this strategy of combining hetero-phase boundaries (PBs) and dislocation engineering could open up new avenues to designing strong and ductile titanium matrix materials.

Modelling principal stress orientations in the Arabian Plate using plate velocities

Abstract We model maximum principal horizontal stress orientations in the Arabian Plate using a 3D finite element approach in conjunction with plate velocities. To capture the impact of geometry and tectonics, the model considers an accurate plate boundary shape and associated deformations. Three primary geological units represent plate architecture: sedimentary cover, crust and upper mantle. The mesh resolution varies to capture important geometrical features. Subsequently, we calculate the stress field using the force balance equation. Displacement boundary conditions are evaluated as accumulative deformation. NE–SW maximum principal horizontal stress (S Hmax ) azimuths dominate in northeastern Saudi Arabia and Kuwait, whilst NW–SE to NNW–SSE define the Dead Sea area. The Red Sea Basin and Saudi Arabia's interior is characterized by north–south S Hmax azimuths. Iraq's western area shows azimuths from NNW–SSE to NW–SE due to the collision at the Zagros Mountain Range, but changes to NE–SW in the east at the Zagros fold-and-thrust belt. An extensive literature review reveals publicly available S Hmax azimuth data which augment the sparse records compiled in the World Stress Map database. Our simulated S Hmax azimuths are consistent with these data. The results further corroborate ongoing tectonic processes, deepen our understanding of in situ stress variation drivers and inform current elastic deformation mechanisms in the Arabian Plate.

High-Cycle Computational Model for Accumulative Deformation of Granular Material under Repeated Traffic Loading

High-Cycle Computational Model for Accumulative Deformation of Granular Material under Repeated Traffic Loading

Dynamic response of OWTs under wind-wave loads considering 3D water-pile-soil interactions

A new three-dimensional (3D) integrated model of offshore wind turbine (OWT) is proposed, which considers the soil-monopile-water interactions and the accumulative deformation of foundations under cyclic loads. The effects of three different modelling methods on the dynamic response of wind turbine are discussed, where three modelling methods are the new WOT model, OWT model with a 3D soil-pile medium without a seawater domain and OWT model with API's spring-type foundation. The numerical results show that the use of API's soil spring may overestimate the fundamental frequency of OWT by up to 32.2%. This leads to inaccurate structural resonance. Meanwhile, a significant displacement drift of the tower top of the new model is observed due to the ratcheting effect, and the OWT with API's spring cannot correct this phenomenon. Consequently, the API method should be used with care in assessing dynamic performance under wind-wave loads. The added mass method considers only the water-structure interaction and excludes the soil-water interaction, and it may underestimate the responses of the tower, blades and monopile, which can render the design of wind turbines unsafe. Additionally, assumption of the parked condition underestimates the structural response, and the frequency of the blades may change during operation.

An empirical formula for the accumulative deformation of saturated clay under different cyclic loading frequencies

Road and subway tunnels in soft clay soils subjected to traffic loading often cause lager settlement. It can pose danger to the surrounding buildings and structures. Hence, it is necessary for engineers to correctly predict the long-term deformation of saturated clay foundations under cyclic loading. In this paper, a series of dynamic triaxial tests were carried out on Nanning clay to investigate the effect of loading frequency and cyclic stress on axial strain accumulation of clay under undrained condition. Results show that loading frequency has a great effect on the axial strain accumulation of clay. Based on the experimental results, an empirical formula for calculating the accumulated deformation of saturated clay under cyclic loading was presented.

The effects of changing the deviatoric and spherical stresses during cyclic loading on the drained response of a sand

Changing the deviatoric and spherical stresses could affect the accumulative deformation behaviour of soils under cyclic loading. Drained cyclic triaxial loading tests were performed on saturated sand to study the dependence of cyclic loading-induced axial and volumetric strain accumulations on changing the deviatoric and spherical stresses in between loading cycles. The change in the stresses was simulated by changing cell pressure and axial load along different stress paths. The variation of axial and volumetric strain accumulations before and after changing the stresses is compared and discussed. It is found that changing the stresses could have different impacts on the axial and volumetric strain accumulations, as the accumulations are affected by different mechanisms. The axial strain accumulation after changing the stresses is affected by the average stress ratio and precedent stress history. The volumetric strain accumulation is hardly affected by changing the stresses unless an increase in the average stress ratio is caused. Both axial and volumetric strain accumulations show independence on the stress path of the disturbance. For the samples with decreasing average stress ratio, the strain accumulation direction after changing the stresses cannot be fully described using Modified Cam Clay flow rule.

Field monitoring and analysis of soil deformation of curved steel pipe jacking in Gongbei tunnel

To ascertain the soil deformation law in the construction of curved pipe jacking, ground deformation, layered settlement and lateral deformation of deep soil have been analyzed by field monitoring of soil deformation data in different types of soil in the curved pipe jacking roof of Gongbei tunnel. The results show that the curved pipe jacking induced ground settlement groove curve shows asymmetry. The variation law of ground settlement and deep soil deformation in different soil is consistent, and the mud pressure, excavation face support force and friction resistance have great influence on the deep soil deformation, but the maximum deformation is related to the soil type. Adjacent curved pipe jacking construction will cause the accumulative deformation of surrounding soil, due to the supporting effect of the completed pipe jacking on surrounding soil, the accumulated value of this part of soil is small. The maximum settlement values of single curved pipe jacking are artificially fill > sand layer > mucky soil. during construction of adjacent jacking pipes, the cumulative deformation values are as follows: mucky soil > artificial fill > sand layer, indicating that the deformation of mucky soil is more significant under multiple disturbances. The soil loss caused by relative position of curved pipe jacking and tunnel is the main reason for the ground settlement deviation. The calculated result of modified Peck formula is accordance with measured values, which can be used to predicate the surface deformation caused by curved pipe jacking.

Geomorphological transformations and future deformation estimations of a large potential landslide in the high-order position area of Diexi, China

Landslides in high-order position areas pose a serious threat to residents located below such areas. Therefore, research on the evolution process and underlying dynamic mechanisms is crucial. The majority of relevant studies are based on landslides that have already occurred; however, the investigation of potential landslides is of higher value. In this study, a progressive potential landslide identification method is proposed with the application of SBAS-InSAR (Small Baseline Subset Interferometric Synthetic Aperture Radar) and subsequently combined with Google Earth, GF-1 (Gaofen-1), GF-2 (Gaofen-2), ZY-3 (Ziyuan-3) and UAV (Unmanned Aerial Vehicle) imagery, and DEM (Digital Elevation Model) for further validation. The proposed method is employed to determine the potential landslide in Tuanjiecun by integrating the multi-period data to simultaneously analyze the evolution and mechanism of the potential landslide. The long short-term memory method is then adopted to predict the evolution trend based on accumulative deformation from SBAS-InSAR. The results suggest that the deformation of Tuanjiecun potential landslide will increase to −238.57 mm. This article provides a new approach for disaster prevention and mitigation by determining a potential landslide using composite remote sensing and predicting the development of the potential landslide on indirect contact monitoring.

Numerical analysis of dynamic behavior of piled embankment under train loading

Piled embankments, which have many advantages, have been widely employed in the construction of railways over soft soil. However, the load transfer mechanism and deformation characteristic induced by train loading, which has great importance for piled embankment design, are not well known and deserve more research attention. In this paper, a three-dimensional numerical model of a piled embankment subjected to train loading is proposed and calibrated by test results, which considers the dynamic behavior of soft clays by a simplified dynamic constitutive model based on bounding surface theory that has been successfully encoded into the ABAQUS. Based on the proposed numerical model, the development of soil arching and accumulative deformation in a piled embankment subjected to train loading is investigated. The load transfer mechanism and deformation characteristics of a piled embankment in terms of the embankment height, velocity of the train, pile spacing and wheel static load are analyzed. The research results can provide some reference for the design of piled embankments under train loading.

Accumulative deformation-based design method for special concentrically braced frames with H-section braces

Accumulative deformation-based fracture models of braces have been developed by researchers for nearly 30 years. These models are used to predict the fracture of braces in a specific time-history analysis of SCBF. However, no attempt has been made to explore statistical accumulative deformation demands of braces under severe earthquakes. Eight SCBF models are designed in this paper for nonlinear time-history analysis to summarize the accumulative deformation demands of SCBF braces. Meanwhile, accumulative deformation-based fracture models of SCBF braces with H-section are proposed by experimental data. Accumulative deformation demands of braces are in good correlation with hysteretic energy demands according to the results of time-history analysis. Hysteretic energy spectrum, energy demands, and accumulative deformation demands of braces are set up in this paper. The method is proposed by balancing the accumulative deformation demands and accumulative deformation limit index of braces. Finally, an example designed by the proposed method is given. Configuration detailing parameters of braces is not only determined by expected ductility but also the strength of SCBF according to the result of the example. The proposed design method can help designers to determine the configuration detailing parameters of braces complied with the strength of SCBF.

Theoretical investigation on characteristics of field reactions of saturated ground subjected to vibrations of inclined pile groups

Inclined pile groups have been adopted in engineering practice (e.g. offshore wind turbines) to withstand strong horizontal environmental loads that are repetitive in nature. Field reactions including the additional stresses and excess pore water pressures are responsible for the cyclic degradation of foundation soil, which may induce the accumulative deformation and fundamental frequency shifting of the marine structure. In this study, a theoretical model incorporating an inclined pile group and a saturated half-space was established, wherein the pile and saturated soil were described by the E–B beam and Biot poroelasticity theories, respectively. The pile and soil were coupled through the receptance matrix, which was established at the pile–soil interaction points in the transform domain. The dynamic impedances of the inclined pile group are first obtained, and then the field responses, including stresses and excess pore water pressure in the saturated ground, are evaluated for different types of loads applied to the pile cap. The frequency response function and spatial distributions of the field responses were obtained for varying rake angle of pile and permeability of soil. It was found that the horizontal force induces the largest responses in the ground when compared to the vertical force and the overturning moment applied to the inclined pile group. It is beneficial to employ an inclined pile group to withstand the horizontal force and overturning moment because the foundation stiffness increases, and the additional stresses in the ground decrease with increasing rake angle.

Hypoplastic model with fabric change effect and semifluidized state for post‐liquefaction cyclic behavior of sand

AbstractThis paper presented the formulation of a novel hypoplastic model for sand considering both the cyclic mobility and large accumulative shear deformation in the post‐liquefaction stage. Based on experimental observations and existing modeling response, two constitutive ingredients were incorporated into the hypoplastic model to improve its prediction accuracy. First, the fabric change effect was considered, enabling a satisfactory simulation of effective stress reduction under undrained cyclic loading. The second component was the introduction of the semifluidized state concept to reflect the modulus degradation and deviatoric strain development of sand at low‐stress state. The capability of the proposed model is demonstrated by the comparisons between the model responses and experimental results of the cyclic behavior of sand under different test conditions. Remarkably, the liquefaction phenomenon and increasing deviatoric strain amplitude during the post‐liquefaction stage were reproduced well by the model.

Quantifying lamellar microstructural effect on the fatigue performance of bimodal Ti-6Al-4V with microdefect

Fatigue performance of metal alloys is inseparably associated with heterogenous microstructure and existing microdefects. The coordinated effects of lamellar microstructure (LM) and microdefect on fatigue performance of bimodal Ti-6Al-4V is studied within the framework of CPFEM. We propose an intragrain weight integration approach able to account for intragranular accumulative deformation. Parametric accumulative difference indicator (ADI) for stress is defined to relatively quantify the lamellar microstructural effect, overcoming the limitations of experimental procedures. The results demonstrate that the increase of β lath and synchronized refinement of LM appreciably improve lamellar microstructural effect. These attributes can be applied to the material design and manufacturing of advanced metal alloys.

Critical dynamic stress for the frozen subgrade soil

Triaxial dynamic tests at the temperature −6 °C were performed on frozen subgrade soil to study accumulative deformation and resilient deformation properties. Based on the shakedown theory, a reliable evaluation for the long-term serviceability of the frozen subgrade was further presented. The influences of confining pressure, dynamic stress amplitude, initial stress path and initial stress ratio on dynamic properties of frozen subgrade soil were analysed. The evolution features of accumulative permanent strain under cyclic loading were experimentally determinated. The boundary functions for plastic shakedown area and plastic creep area were further established. Critical dynamic stresses for the different deformation areas can be calculated by the experimental data and the proposal formula. The influences of consolidation pressure and initial stress ratio on critical dynamic stress were discussed in detail. The distribution characteristics (envelope line loci) of the critical dynamic stress were investigated in the mean stress-the shear stress space.