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1.
This paper deals with numerical modelling of anisotropic damage induced by desaturation and resaturation processes in a brittle rock. This study is conducted in the framework of geological barrier safety analysis for deep disposal of nuclear waste. A non-linear poroelastic model coupled with anisotropic damage is proposed for constitutive modelling of unsaturated rock. A fully coupled FEM method is used for modelling of hydromechanical coupling problems. Instantaneous phase change without dissipation between water liquid phase and vapour is included. Parametric studies are performed to investigate influences of main factors involved in such processes. Rock damage induced by excavation, desaturation and resaturation is evaluated. Finally, we analyse the importance of taking into account the correlation between induced damage and rock permeability. 相似文献
2.
A coupled two‐phase fluid flow and elastoplastic deformation model for unsaturated soils: theory,implementation, and application 
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下载免费PDF全文 Although numerous numerical models have been proposed for simulating the coupled hydromechanical behaviors in unsaturated soils, few studies satisfactorily reproduced the soil–water–air three‐phase coupling processes. Particularly, the impacts of deformation dependence of water retention curve, bonding stress, and gas flow on the coupled processes were less examined within a coupled soil–water–air model. Based on our newly developed constitutive models (Hu et al., 2013, 2014, 2015) in which the soil–water–air couplings have been appropriately captured, this study develops a computer code named F2Mus3D to investigate the coupled processes with a focus on the above impacts. In the numerical implementation, the generalized‐α time integration scheme was adopted to solve the equations, and a return‐mapping implicit stress integration scheme was used to update the state variables. The numerical model was verified by two well‐designed laboratory tests and was applied for modeling the coupled elastoplastic deformation and two‐phase fluid flow processes in a homogenous soil slope induced by rainfall infiltration. The simulation results demonstrated that the numerical model well reproduces the initiation of a sheared zone at the toe of the slope and its propagation toward the crest as the rain infiltration proceeds, which manifests a typical mechanism for rainfall‐induced shallow landslides. The simulated plastic strain and deformation would be remarkably underestimated when the bonding stress and/or the deformation‐dependent nature of hydraulic properties are ignored in the coupled model. But on the contrary, the negligence of gas flow in the slope soil results in an overestimation of the rainfall‐induced deformation. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
3.
The interparticle bonding effect due to water menisci plays an important role in the hydromechanical coupling properties of unsaturated soils. This paper presents an unsaturated hydromechanical coupling model that considers the influence of matric suction, degree of saturation, and microscopic pore structure on the interparticle bonding effect. The enhanced effective stress and bonding variable are selected as constitutive variables. The bonding variable is correlated with the ratio between unsaturated void ratio and saturated void ratio. The deformation characteristics of unsaturated soils are described based on the bounding surface plasticity theory. A soil–water characteristic model that considers deformation and hydraulic hysteresis is integrated into the constitutive model to achieve hydromechanical coupling. The proposed model can effectively describe the hydromechanical coupling characteristics and the meniscus bonding force of unsaturated bimodal structure soils; the model parameters can be easily obtained through routine experiments. The experimental results of unsaturated isotropic compression, the wetting/drying cycle, and unsaturated triaxial shear tests are used to validate the capability of the proposed model.
相似文献4.
Prediction of unsaturated soil behavior during earthquake loading has received increasing attention in geotechnical engineering research and practice in recent years. Development of a fully coupled analysis procedure incorporating a coupled hydromechanical elastoplastic constitutive model for dynamic analysis of unsaturated soils has, however, been limited. This paper presents the implementation of a coupled hydromechanical elastoplastic constitutive model into a fully coupled dynamic analysis procedure and its validation using a centrifuge test. First, the fully coupled finite element equations governing the dynamic behavior of unsaturated soils with the solid skeleton displacement, pore water pressure, and pore air pressure as nodal unknowns are briefly presented. The closest point projection method is then utilized to implement the coupled hydromechanical elastoplastic constitutive model into the finite element equations. The constitutive model includes hysteresis in soil–water characteristic curves, cyclic elastoplasticity of the solid skeleton, and the coupling mechanisms between the SWCCs and the solid skeleton. Finally, the analysis procedure is validated using the results from a dynamic centrifuge test on an embankment constructed of compacted unsaturated silt subjected to base shaking. Reasonable comparisons between the predicted and measured accelerations, settlements, and deformed shapes are obtained.
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《Computers and Geotechnics》2006,33(6-7):316-329
The aim of the paper is to provide new elements concerning the constitutive behavior of sedimentary rocks and the numerical aspects for basin simulators. A comprehensive model for mechanical compaction of sedimentary basins is developed within finite poroplasticity setting. Particular concern is paid to the effects of large porosity changes on the poromechanical properties of the sediment material. A simplified micromechanics-based approach is used to account for the stiffness increase and hardening induced by large plastic strains.A key challenge for numerical assessment of sedimentary basin evolution is to integrate multiple coupled processes in the context of open material systems. To this end, a numerical approach inspired from the ‘deactivation/reactivation’ method used for the simulation of excavation process and lining placement in tunnel engineering, has been developed. Periods of sediments accretion are simulated by progressive activation of the gravity forces within a fictitious closed system. Fundamental components of the constitutive model developed before (hydromechanical coupling, dependence of poroelastic properties on large plasticity, impact of irreversible porosity changes on the hardening rule, evolution of permeability with porosity) are included into our finite element code.Illustrative examples of basin simulation are performed in the one-dimensional case. Various aspects of the constitutive model are investigated. Their influence on the corresponding basin response is analyzed in terms of compaction law, porosity and fluid pressure profiles. 相似文献
7.
在实际隧道施工过程中,隧道开挖引起地下岩体应力重分布使得围岩的微裂纹扩展损伤,并伴随有塑性流动变形。在地下水环境中对于孔隙和微裂隙围岩介质受到应力作用时,在内部将产生高孔隙水压力影响岩石的力学性质,也改变了围岩的破坏模式。为了研究损伤引起的刚度退化和塑性导致的流动两种破坏机制的耦合作用,从弹塑性力学和损伤理论的角度出发,同时引入修正有效应力原理来考虑孔隙水压力的作用,建立基于Drucker-Prager屈服准则的弹塑性损伤本构模型;针对该本构模型推导了孔隙水压力作用下弹塑性损伤本构模型的数值积分算法-隐式返回映射算法,分别对预测应力返回到屈服面的光滑圆锥面或尖点奇异处两种可能的情况给出了详细的描述,隐式返回映射算法具有稳定性和准确性的特点;大多数弹塑性损伤模型中涉及参数多且不易确定的问题,采用反分析方法获得损伤参数,解决了损伤参数不易确定的难题;采用面向对象的编程方法,使用C++语言编制了弹塑性损伤本构求解程序,并对所建立的弹塑性损伤模型和所编程序进行了试验和数值两个方面的验证;最后将其在吉林抚松隧道工程中进行应用,模拟了塑性区和损伤区的发展变化。研究结果表明：所建立的弹塑性损伤本构模型能够较好地描述岩石的力学性能、塑性和损伤变化趋势,所编程序能够进行实际工程问题的模拟,对现场施工给予一定的指导。 相似文献
8.
Hydromechanical coupling in geologic processes 总被引：6，自引：2，他引：4
Earth's porous crust and the fluids within it are intimately linked through their mechanical effects on each other. This paper
presents an overview of such "hydromechanical" coupling and examines current understanding of its role in geologic processes.
An outline of the theory of hydromechanics and rheological models for geologic deformation is included to place various analytical
approaches in proper context and to provide an introduction to this broad topic for nonspecialists.
Effects of hydromechanical coupling are ubiquitous in geology, and can be local and short-lived or regional and very long-lived.
Phenomena such as deposition and erosion, tectonism, seismicity, earth tides, and barometric loading produce strains that
tend to alter fluid pressure. Resulting pressure perturbations can be dramatic, and many so-called "anomalous" pressures appear
to have been created in this manner. The effects of fluid pressure on crustal mechanics are also profound. Geologic media
deform and fail largely in response to effective stress, or total stress minus fluid pressure. As a result, fluid pressures
control compaction, decompaction, and other types of deformation, as well as jointing, shear failure, and shear slippage,
including events that generate earthquakes. By controlling deformation and failure, fluid pressures also regulate states of
stress in the upper crust.
Advances in the last 80 years, including theories of consolidation, transient groundwater flow, and poroelasticity, have been
synthesized into a reasonably complete conceptual framework for understanding and describing hydromechanical coupling. Full
coupling in two or three dimensions is described using force balance equations for deformation coupled with a mass conservation
equation for fluid flow. Fully coupled analyses allow hypothesis testing and conceptual model development. However, rigorous
application of full coupling is often difficult because (1) the rheological behavior of geologic media is complex and poorly
understood and (2) the architecture, mechanical properties and boundary conditions, and deformation history of most geologic
systems are not well known. Much of what is known about hydromechanical processes in geologic systems is derived from simpler
analyses that ignore certain aspects of solid-fluid coupling. The simplifications introduce error, but more complete analyses
usually are not warranted. Hydromechanical analyses should thus be interpreted judiciously, with an appreciation for their
limitations. Innovative approaches to hydromechanical modeling and obtaining critical data may circumvent some current limitations
and provide answers to remaining questions about crustal processes and fluid behavior in the crust.
Electronic Publication 相似文献
9.
裂隙的剪胀特性及扩展演化规律对岩体的渗流特性具有重要影响。为揭示裂隙剪胀及扩展演化对岩体渗流的影响,基于残余强度提出了一种能较好描述岩石硬化-软化特性的全剪切本构关系;结合剪切变形与裂隙开度的关系,利用最小势能原理和立方定律,建立了压剪作用下考虑裂隙剪胀特性的渗流应力耦合模型;假定压剪作用下裂隙发生Ⅰ型扩展,提出了伴有翼型裂纹的渗流模型,该模型不仅考虑了岩石的剪胀特性,更反映了裂隙扩展过程渗流的演化规律。对不同裂隙粗糙度的剪切应力-位移曲线进行分析,全剪切本构模型表现出较高的拟合精度。在剪切应力-位移关系基础上,通过剪切渗流试验数据对压剪作用下渗流模型进行验证,结果表明,该模型能较好地描述岩体剪胀阶段渗透性演化规律。利用等效裂隙简化裂隙网络,并通过试验数据进行验证,证实了裂隙扩展过程渗流-应力耦合模型的准确性与适用性。 相似文献
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This paper presents a computational homogenization approach in the framework of poromechanics. A fully coupled hydromechanics problem is formulated at the macroscopic scale. The constitutive equations are replaced by results of numerical computations on a Representative Elementary Volume in order to obtain the overall stress of the mixture as well as its transmissivity properties. At the microscale, the material is assumed to be composed of an assembly of hyperelastic grains connected by cohesive interfaces. These interfaces are also channels of a network where the fluid can percolate. The fluid acts on the boundaries of the grains and influences the behavior of the cohesive interfaces. Conversely, the opening of the interfaces induces changes in the transmissivity properties of the corresponding channels. This yields a fully coupled hydromechanical problem at the microscopic scale. The finite element method is considered for the numerical solutions at both scales, the present approach extending the purely mechanical FE2 scheme to the coupled hydromechanical framework. The local macroscopic behavior resulting from the homogenization scheme is illustrated on different numerical tests. The results clearly show the coupling between damage and fluid permeability in the overall response, as a consequence of the small-scale interaction between the action of the percolating fluid, the deformation of the solid skeleton, and the failure of the cohesive interfaces. 相似文献
12.
Akira Murakami Takayuki Shuku Shin‐ichi Nishimura Kazunori Fujisawa Kazuyuki Nakamura 《国际地质力学数值与分析法杂志》2013,37(11):1642-1669
A computational method, incorporating the finite element model (FEM) into data assimilation using the particle filter, is presented for identifying elasto‐plastic material properties based on sequential measurements under the known changing traction boundary conditions to overcome some difficulties in identifying the parameters for elasto‐plastic problems from which the existing inverse analysis strategies have suffered. A soil–water coupled problem, which uses the elasto‐plastic constitutive model, is dealt with as the geotechnical application. Measured data on the settlement and the pore pressure are obtained from a synthetic FEM computation as the forward problem under the known parameters to be identified for both the element tests and the ground behavior during the embankment construction sequence. Parameter identification for elasto‐plastic problems, such as soil behavior, should be made by considering the measurements of deformation and/or pore pressure step by step from the initial stage of construction and throughout the deformation history under the changing traction boundary conditions because of the embankment or the excavation because the ground behavior is highly dependent on the loading history. Thus, it appears that sequential data assimilation techniques, such as the particle filter, are the preferable tools that can provide estimates of the state variables, that is, deformation, pore pressure, and unknown parameters, for the constitutive model in geotechnical practice. The present paper discusses the priority of the particle filter in its application to initial/boundary value problems for elasto‐plastic materials and demonstrates a couple of numerical examples. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
Analytical solution to 1D coupled water infiltration and deformation in unsaturated soils 总被引：1，自引：0，他引：1
An analytical solution to 1D coupled water infiltration and deformation is derived using a Fourier integral transform. Exponential functional forms are used to represent the hydraulic conductivity–pore‐water pressure relationship and the soil‐water characteristic curve. Fredlund's incremental‐linear constitutive model for unsaturated soils is adopted. The analytical solution considers arbitrary initial pore‐water pressure distributions and flux and pressure boundary conditions. The corresponding analytical solutions to coupled steady‐state problems are also obtained. The analytical solutions demonstrate that the coupling of seepage and deformation plays an important role in water infiltration in unsaturated soils. In the early stages of infiltration, the difference between uncoupled and coupled conditions becomes marked over time, and in late stages, the difference caused by the coupling effects diminishes toward the steady state. The difference between the uncoupled and coupled conditions increases with decreasing desaturation coefficient (α). Pore‐water pressure or deformation changes caused by the coupling effects are mainly controlled by the degree of soil volume change due to a change in soil suction (H). The smaller the absolute value of H, the greater the effect of coupling on the infiltration and deformation. The ratio of rainfall intensity to saturated permeability (q/ks) also has a strong influence on the coupled seepage and deformation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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The paper deals with the modeling of some aspects, such as the formulation of constitutive equations for sediment material or finite element approach for basin analysis, related to mechanical compaction in sedimentary basins. In addition to compaction due to gravity forces and pore‐pressure dissipation, particular emphasis is given to the study of deformation induced by tectonic sequences. The numerical model relies upon the implementation of a comprehensive constitutive model for the sediment material formulated within the framework of finite poroplasticity. The theoretical model accounts for both hydromechanical and elasticity–plasticity coupling due to the effects of irreversible large strains. From the numerical viewpoint, a finite element procedure specifically devised for dealing with sedimentary basins as open systems allows to simulate within a two‐dimensional setting the process of sediment accretion or erosion. Several basin simulations are presented. The main objective is to analyze the behavior of a sedimentary basin during the different phases of its life cycle: accretion phase, pore‐pressure dissipation phase and compressive/extensional tectonic motions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
16.
Xiong Yong-lin Ye Guan-lin Xie Yi Ye Bin Zhang Sheng Zhang Feng 《Acta Geotechnica》2019,14(2):313-328
This study presents a sophisticated elastoplastic constitutive model for unsaturated soil using Bishop-type skeleton stress and degree of saturation as state variables in the framework of critical state soil mechanism. The model is proposed in order to describe the coupled hydromechanical behavior of unsaturated soil irrespective of what kind of the loadings or the drainage conditions may be. At the same time, a water retention characteristic curve considering the influence of deformation on degree of saturation is also proposed. In the model, the superloading and subloading concepts are introduced to consider the influences of overconsolidation and structure on deformation and strength of soils. The proposed model only employs nine parameters, among which five parameters are the same as those used in Cam-Clay model. The other four parameters have the clear physical meanings and can be easily determined by conventional soil tests. The capability and accuracy of the proposed model have been validated carefully through a series of laboratory tests such as isotropic loading tests and triaxial monotonic and cyclic compression tests under different mechanical and hydraulic conditions.
相似文献17.
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岩盐弹塑性损伤耦合模型研究 总被引：5，自引：1，他引：4
岩盐力学模型是进行能源岩盐储存工程稳定性分析的基础,而损伤和塑性机制并存且相互耦合是岩盐力学行为的基本特点。采用云应岩盐,进行了多组围压条件下的三轴压缩试验,分析了不同围压下岩盐的变形特征。在试验分析的基础上,提出了一种能够描述岩盐特性的弹塑性损伤耦合的模型,该模型描述了岩盐损伤的演化和塑性变形的耦合关系,并引入了一种非关联的塑性流动法则来描述岩盐从塑性体积压缩到膨胀的转化。采用该模型对在三轴压缩下的岩盐应力-应变关系进行了模拟分析,并与试验数据进行了对比,结果表明该模型能够较好地描述岩盐的主要力学和变形特性。 相似文献
19.
目前国内关于CO2咸水层封存尚处于先导性和试验性研究阶段,对超临界CO2注入过程中岩层力学响应和流体运移的理论与技术方面的认识还不完善。为研究CO2注入下岩层变形和流体运移,基于两相流动数学模型,给出了超临界CO2和咸水质量守恒方程;采用毛细压力和有效饱和度的关系式,将质量守恒方程变换成以毛细压力为变量的表达式,以便于考虑流体压力对岩层的影响。提出了无流体压力影响下的岩层力学本构模型,该模型能够同时考虑岩层的塑性变形和损伤。分析了两相流体-岩层相互作用机制:一方面,采用有效应力原理,考虑流体压力对岩层的力学影响;另一方面,通过岩层固有渗透率变化考虑岩层变形对流体运移的影响。 相似文献
20.
A coupled poroplastic damage model accounting for cracking effects on both hydraulic and mechanical properties of unsaturated media 下载免费PDF全文
下载免费PDF全文 Tuan Anh Bui Henry Wong Frederic Deleruyelle Annan Zhou Xiaoqin Lei 《国际地质力学数值与分析法杂志》2016,40(5):625-650
Damage induced by microcracking affects not only the mechanical behaviour of geomaterials but also their hydraulic properties. Evaluating these impacts is important for many engineering applications, such as the safety assessment of radioactive waste disposal facilities. This paper presents a new constitutive model accounting simultaneously for the impact of damage on hydraulic and mechanical properties of unsaturated poroplastic geomaterials. The hydro‐mechanical coupling is formulated by means of the thermodynamic framework for partially saturated media, extended by taking into account isotropic damage and plasticity. State and complementary laws are governed by the so‐called plastic effective stress and equivalent pore pressure. Assuming a bimodal pore size distribution for cracked porous media, the hydraulic part (water retention curve and hydraulic conductivity) is modelled using phenomenological functions of damage variable. The participation of damage on both mechanical and hydraulic part enables this model to describe bilateral couplings between them. This coupled model is then validated against a number of experimental data obtained from Callovo‐Oxfordian argillite, which is the possible host rock for a radioactive waste disposal in France. Parametric studies are also carried out to check the consistency and to better demonstrate the bilateral couplings in the model. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献