Multifield coupling model and its applications for pile foundation in permafrost   总被引：2，自引：0，他引：2  

WU Yaping    ZHU Yuanlin  GUO Chunxiang  SU Qiang & MA Wei . School of Civil Engineering  Lanzhou Jiaotong University  Lanzhou  China  . State Key Laboratory of Frozen Soil Engineering  Cold  Arid Regions Environmental  Engineering Research Institute  Chinese Academy of Sciences  Lanzhou  China 《中国科学D辑(英文版)》2005,48(7)

In the construction of Qinghai-Tibet railway,to avoid diseases caused by frost heave and thaw col-lapse of frozen ground,besides the normal bridges over the rivers,a lot of dry bridge structures have been built to replace subgrade in the regions of high tem-perature and high ice content frozen soil.So,the problems on forming mechanism of bearing capacity of pile foundation in cold regions already become one of hot spot problems in frozen soil engineering.Freezing force and frost heave force ar…  相似文献   

The coupling instability of Rossby and topographic Rossby waves in the equatorial area     

CHAO Jiping    LIU Lin  & YU Weidong . Laboratory of Marine Science  Numerical Modeling  State Oceanic Administration  Qingdao  China  . National Research Center for Marine Environmental Forecasts  State Oceanic Administration  Beijing  China  . Ocean University of China  Qingdao  China 《中国科学D辑(英文版)》2005,48(10)

Before the 1980s, El Ni?o was believed as the sea surface warming along the coast of Peru in South America. As the positive anomaly strengths, the warm water expands westward along the equator to form large area of anomalous high sea surface temperature. Rasmusson and Carpenter (1982) summarized the de-velopment process of the sea surface warm water and the corresponding wind field[1] during ENSO cylce. However, this canonical El Ni?o was questioned by 1982-1983 warm episode and later dat…  相似文献   

An attempt to estimate isotropic and anisotropic lateral structure of the Earth by spectral inversion incorporating mixed coupling   总被引：2，自引：0，他引：2  

Hitoshi Oda 《Geophysical Journal International》2005,160(2):667-682

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Hydromechanical coupling in response to earthquakes: on the possible consequences for aftershocks   总被引：1，自引：0，他引：1  

Pierre Gavrilenko 《Geophysical Journal International》2005,161(1):113-129

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Geographic Information Analysis     

《The Professional geographer》2005,57(4):624-626

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Curved structures and interference fold patterns associated with lateral ramps in the Eastern Cordillera, Central Andes of Argentina     

Ricardo Mon  Csar Rubn Monaldi  Jos Antonio Salfity 《Tectonophysics》2005,399(1-4):173

The conspicuous curved structures located at the eastern front of the Eastern Cordillera between 25° and 26° south latitude is coincident with the salient recognized as the El Crestón arc. Major oblique strike-slip faults associated with these strongly curved structures were interpreted as lateral ramps of an eastward displaced thrust sheet. The displacement along these oblique lateral ramps generated the local N–S stress components responsible for the complex hanging wall deformation. Accompanying each lateral ramp, there are two belts of strong oblique fault and folding: the upper Juramento River valley area and El Brete area.On both margins of the Juramento River upper valley, there is extensive map-scale evidence of complex deformation above an oblique ramp. The N–S striking folds originated during Pliocene Andean orogeny were subsequently or simultaneously folded by E–W oriented folds. The lateral ramps delimiting the thrust sheet coincident with the El Crestón arc salient are strike-slip faults emplaced in the abrupt transitions between thick strata forming the salient and thin strata outside of it. El Crestón arc is a salient related to the pre-deformational Cretaceous rift geometry, which developed over a portion of this basin (Metán depocenter) that was initially thicker. The displacement along the northern lateral ramp is sinistral, whereas it is dextral in the southern ramp. The southern end of the Eastern Cordillera of Argentina shows a particular structure reflecting a pronounced along strike variations related to the pre-deformational sedimentary thickness of the Cretaceous basin.  相似文献   

Influence of transducer-ground coupling on vibration measurements   总被引：1，自引：0，他引：1  

G. R. Adhikari  A. I. Theresraj  R. N. Gupta 《Fragblast: International Journal for Blasting and Fragmentation》2005,9(2):79-92

Various methods of transducer mounting provide varying degrees of coupling between the transducer and the measurement surface. The influence of four of these methods on vibration measurements was studied. For this purpose, the first transducer was placed freely on a horizontal surface, the second one was 'sandbagged', the third one was 'spiked' and the fourth one was completely buried in soil. These transducers were mounted side by side and ground vibrations were monitored for 14 blasts at an opencast coal mine.

Ground vibrations in terms of peak particle velocity, peak vector sum and frequency with different mounting methods were analysed. Assuming the data of the buried transducer as the most acceptable one, relative values of other transducers were determined and plotted. For the given tolerance for instrumental and human errors, anomalous readings were found in some cases. The waveforms of the buried transducer were then compared with those of others. Clear distortion in the waveforms or a very low correlation coefficient between two waveforms was suspected poor coupling.

The results indicate that decoupling is most likely with the surface transducer. However, the sandbagged and spiked transducers are also prone to decoupling. Decoupling can result in higher or lower ground vibration. Therefore, burial should be the preferred method for mounting of transducers in soil.  相似文献   

Discrete element method modeling of inherently anisotropic rocks under uniaxial compression loading          下载免费PDF全文

K. Duan  C.Y. Kwok  M. Pierce 《国际地质力学数值与分析法杂志》2016,40(8):1150-1183

A new numerical approach is proposed in this study to model the mechanical behaviors of inherently anisotropic rocks in which the rock matrix is represented as bonded particle model, and the intrinsic anisotropy is imposed by replacing any parallel bonds dipping within a certain angle range with smooth‐joint contacts. A series of numerical models with β = 0°, 15°, 30°, 45°, 60°, 75°, and 90° are constructed and tested (β is defined as the angle between the normal of weak layers and the maximum principal stress direction). The effect of smooth‐joint parameters on the uniaxial compression strength and Young's modulus is investigated systematically. The simulation results reveal that the normal strength of smooth‐joint mainly affects the behaviors at high anisotropy angles (β > 45°), while the shear strength plays an important role at medium anisotropy angles (30°–75°). The normal stiffness controls the mechanical behaviors at low anisotropy angles. The angle range of parallel bonds being replaced plays an important role on defining the degree of anisotropy. Step‐by‐step procedures for the calibration of micro parameters are recommended. The numerical model is calibrated to reproduce the behaviors of different anisotropic rocks. Detailed analyses are conducted to investigate the brittle failure process by looking at stress‐strain behaviors, increment of micro cracks, initiation and propagation of fractures. Most of these responses agree well with previous experimental findings and can provide new insights into the micro mechanisms related to the anisotropic deformation and failure behaviors. The numerical approach is then applied to simulate the stress‐induced borehole breakouts in anisotropic rock formations at reduced scale. The effect of rock anisotropy and stress anisotropy can be captured. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Implicit integration under mixed controls of a breakage model for unsaturated crushable soils          下载免费PDF全文

Yida Zhang  Giuseppe Buscarnera 《国际地质力学数值与分析法杂志》2016,40(6):887-918

This paper discusses a series of stress point algorithms for a breakage model for unsaturated granular soils. Such model is characterized by highly nonlinear coupling terms introduced by breakage‐dependent hydro‐mechanical energy potentials. To integrate accurately and efficiently its constitutive equations, specific algorithms have been formulated using a backward Euler scheme. In particular, because implementation and verification of unsaturated soil models often require the use of mixed controls, the incorporation of various hydro‐mechanical conditions has been tackled. First, it is shown that the degree of saturation can be replaced with suction in the constitutive equations through a partial Legendre transformation of the energy potentials, thus changing the thermomechanical state variables and enabling a straightforward implementation of a different control mode. Then, to accommodate more complex control scenarios without redefining the energy potentials, a hybrid strategy has been used, combining the return mapping scheme with linearized constraints. It is shown that this linearization strategy guarantees similar levels of accuracy compared with a conventional strain–suction‐controlled implicit integration. In addition, it is shown that the use of linearized constraints offers the possibility to use the same framework to integrate a variety of control conditions (e.g., net stress and/or water‐content control). The convergence profiles indicate that both schemes preserve the advantages of implicit integration, that is, asymptotic quadratic convergence and unconditional stability. Finally, the performance of the two implicit schemes has been compared with that of an explicit algorithm with automatic sub‐stepping and error control, showing that for the selected breakage model, implicit integration leads to a significant reduction of the computational cost. Such features support the use of the proposed hybrid scheme also in other modeling contexts, especially when strongly nonlinear models have to be implemented and/or validated by using non‐standard hydro‐mechanical control conditions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

The influence of coupled physical swelling and chemical reactions on deformable geomaterials     

Yue Ma  Xiao‐Hui Chen  Lee J. Hosking  Hai‐Sui Yu  Hywel R. Thomas  Simon Norris 《国际地质力学数值与分析法杂志》2021,45(1):64-82

Coupled thermo‐hydro‐mechanical‐chemical modelling has attracted attention in past decades due to many contemporary geotechnical engineering applications (e.g., waste disposal, carbon capture and storage). However, molecular‐scale interactions within geomaterials (e.g., swelling and dissolution/precipitation) have a significant influence on the mechanical behaviour, yet are rarely incorporated into existing Thermal‐Hydro‐Mechanical‐Chemical (THMC) frameworks. This paper presents a new coupled hydro‐mechanical‐chemical constitutive model to bridge molecular‐scale interactions with macro‐physical deformation by combining the swelling and dissolution/precipitation through an extension of the new mixture‐coupling theory. Entropy analysis of the geomaterial system provides dissipation energy, and Helmholtz free energy gives the relationship between solids and fluids. Numerical simulation is used to compare with the selected recognized models, which demonstrates that the swelling and dissolution/precipitation processes may have a significant influence on the mechanical deformation of the geomaterials.  相似文献