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Soil pressure and pore pressure for seismic design of tunnels revisited: considering water-saturated, poroelastic half-space

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Earthquake Engineering and Engineering Vibration 2020年第1期19卷 17-36页

作者： Zhu Jun Liang Jianwen State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300354China School of Civil Engineering Tianjin UniversityTianjin 300354China

This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.

关键词： seismic soil pressure seismic pore pressure dynamic soil-tunnel interaction water-saturated poroelastic

The 3-D non-axisymmetrical Lamb's problem in transversely isotropic saturated poroelastic media

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Science China(Technological Sciences) 2004年第5期47卷 526-549页

作者： HUANG Yi1 & WANG Xiaogang1,2 1. School of Civil Engineering, Xian University of Architecture & Technology, Xian 710055, China 2. Department of Civil Engineering, Qinghai University, Xining 810016, China Correspondence should be addressed to Huang Yi (email: huangyih@***) Received April 15, 2004 revised July 12, 2004 School of Civil Engineering Xi’an University of Architecture & Technology Xi’an China Department of Civil Engineering Qinghai University Xining China

Based on Biots theory on fluid-saturated porous media, the displacement functions are adopted to convert the 3-D Biots wave equations in the cylindrical coordinate for transversely isotropic saturated poroelastic media into two棗one 6-order and one 2-order棗uncoupling differential governing equations. Then, the differential equations are solved by the Fourier expanding and Hankel integral transform method. Integral solutions of soil skeleton displacements and pore pressure as well as the total stresses for poroelastic media are obtained. Furthermore, the systematic study on Lambs problems for the transversely isotropic saturated poroelastic media is performed. Integral solutions for surface radial, vertical and circumferential displacements are obtained in both cases of drained surface and undrained surface under the vertical and horizontal harmonic excitation force. In the end of this paper, the numerical examples are presented. The calculation results indicate that the difference between the model of isotropic saturated poroelastic media and that of transversely isotropic saturated poroelastic media is obvious.

关键词： transversely isotropic saturated poroelastic media, Biot's wave equations, Lamb's problems.

Wave Propagation Model in a Human Long poroelastic Bone under Effect of Magnetic Field and Rotation

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Computers, Materials & Continua 2021年第8期68卷 1485-1504页

作者： A.M.Abd-Alla Hanaa Abu-Zinadah S.M.Abo-Dahab J.Bouslimi M.Omri Department of Mathematics Sohag UniversitySohagEgypt Department of Statistics University of JeddahCollege of ScienceJeddahSaudi Arabia Department of Mathematics South Valley UniversityQena83523Egypt Department of Engineering Physics and Instrumentation National Institute of Applied Sciences and TechnologyCarthage UniversityTunisia Department of Physics Taif UniversityTaifSaudi Arabia Deanship of Scientific Research King Abdulaziz UniversityJeddahSaudi Arabia

This article is aimed at describing the way rotation and magnetic field affect the propagation of waves in an infinite poroelastic cylindrical bone.It offers a solution with an exact closed form.The authors got and examined numerically the general frequency equation for poroelastic bone.Moreover,they calculated the frequencies of poroelastic bone for different values of the magnetic field and rotation.Unlike the results of previous studies,the authors noticed little frequency dispersion in the wet bone.The proposed model will be applicable to wide-range parametric projects of bone mechanical response.Examining the vibration of surface waves in rotating cylindrical,long human bones under the magnetic field can have an impact.The findings of the study are offered in graphs.Then,a comparison with the results of the literature is conducted to show the effect of rotation and magnetic field on the wave propagation phenomenon.It is worth noting that the results of the study highly match those of the literature.

关键词： Propagation of waves rotation magnetic field poroelastic wet bone natural frequency magnetic field

Acoustic wave propagation simulation in a poroelastic medium saturated by two immiscible fluids using a staggered finite-difference with a time partition method

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Science China(Physics,Mechanics & Astronomy) 2008年第7期51卷 723-744页

作者： ZHAO HaiBo WANG XiuMing Institute of Acoustics Chinese Academy of SciencesBeijing 100080China

Based on the three-phase theory proposed by Santos, acoustic wave propagation in a poroelastic medium saturated by two immiscible fluids was simulated using a staggered high-order finite-difference algorithm with a time partition method, which is firstly applied to such a three-phase medium. The partition method was used to solve the stiffness problem of the differential equations in the three-phase theory. Considering the effects of capillary pressure, reference pressure and coupling drag of two fluids in pores, three compressional waves and one shear wave predicted by Santos have been correctly simulated. Influences of the parameters, porosity, permeability and gas saturation on the velocities and amplitude of three compressional waves were discussed in detail. Also, a perfectly matched layer (PML) absorbing boundary condition was firstly implemented in the three-phase equations with a staggered-grid high-order finite-difference. Comparisons between the proposed PML method and a commonly used damping method were made to validate the efficiency of the proposed boundary absorption scheme. It was shown that the PML works more efficiently than the damping method in this complex medium. Additionally, the three-phase theory is reduced to the Biot's theory when there is only one fluid left in the pores, which is shown in Appendix. This reduction makes clear that three-phase equation systems are identical to the typical Biot's equations if the fluid saturation for either of the two fluids in the pores approaches to zero.

关键词： acoustic waves poroelastic media immiscible fluids staggered grids perfectly matched layers

Dynamic response of a poroelastic stratum to moving oscillating load

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Science China(Physics,Mechanics & Astronomy) 2008年第7期51卷 883-893页

作者： CHEN YuanGuo JIN Bo School of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China

The dynamic response of a poroelastic stratum subjected to moving load is studied. The governing dynamic equations for poroelastic medium are solved by using Fourier transform. The general solutions for the stresses and displacements in the transformed domain are established. Based on the general solutions, with the consideration of boundary conditions, the final expressions of stresses and displacements in physical domain are put forward for the three-dimensional single-layer medium. Some numerical solutions for the stresses, displacements and pore fluid pressure are presented and reveal that the response of a poroelastic stratum varies obviously with the moving velocity.

关键词： poroelastic stratum Biot’s dynamic equation Fourier transform moving oscillating load

Effect of magnetic field on poroelastic bone model for internal remodeling

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Applied Mathematics and Mechanics(English Edition) 2013年第7期34卷 889-906页

作者： A.M.ABD-ALLA S.M.ABO-DAHAB Department of Mathematics Faculty of Sciences Taif University Department of Mathematics Faculty of Science Sohag University Department of Mathematics Faculty of Science South Valley University

This paper studies the effects of the magnetic field and the porosity on a poroelastic bone model for internal remodeling. The solution of the internal bone remodeling process induced by a magnetic field is presented. The bone is treated as a poroelastic material by Biot＇s formulation. Based on the theory of small strain adaptive elasticity, a theoretical approach for the internal remodeling is proposed. The components of the stresses, the displacements, and the rate of internal remodeling are obtained in analytical forms, and the numerical results are represented graphically. The results indicate that the effects of the magnetic field and the porosity on the rate of internal remodeling in bone are very pronounced.

关键词： wave propagation poroelastic wet bone internal remodeling magnetic field

A poroelastic numerical model for simulation of hydraulic fracture propagation:Application to Upper Safa formation-Western Desert-Egypt

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Petroleum Research 2020年第1期5卷 39-51页

作者： Reda Abdel Azim Petroleum Engineering Department American University of KurdistanDohoukIraq

The hydraulic fracturing in tight sand formations has a significant importance in improving its production potential.In this study,a poroelastic numerical model is presented in order to study the reservoirs and rock mechanical properties that affect the propagation of the hydraulic fracture.The poroelastic model simulate fully coupled fluid flow,pressures and stress changes by using finite element technique.The results show that the formation permeability and fracture toughness are key parameters in the design of hydraulic fracture treatment.A case study applied in Upper Safa formation in a well-located western desert Egypt.The formation is very tight with permeability of 0.1md and the objective here is to optimize the design procedures for hydraulic fracture treatment.The results show that the formation needs to be pumped for about 5min to produce hydraulic fracture length of 182 ft.In addition,the total pumping time(30 min)is vital to produce the desired total fracture length of 1000 ft.

关键词： Fracture propagation Finite element Upper Safa formation poroelastic Leak off model

poroelastic Modelling of Gravitational Compaction

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Open Journal of Physical Chemistry 2019年第3期9卷 126-169页

作者： Pieter Broer van der Weg Unilever R & D Vlaardingen The Netherlands

A dynamic in-silico model captures the kinetics of 1-d gravity driven instabilities, in gravity or centrifuge, of fluid-infiltrated poroelastic media in a partial differential equation (pde). The pde yields the porosity profile over height and time for the given initial and boundary conditions, during slow compaction in counter-current fluid drainage. Processes captured are amongst others sedimentation, creaming and subsidence. The most important limiting prerequisite is that the incompressible dispersed medium is sufficiently structured and/or concentrated that it compacts during slow drainage, without segregation in sizes or in components. For Unilever, modeling of gravitational instability of products is important to quantify or extrapolate long time behavior during shelf life or use centrifuge data to quickly predict long term shelf performance of products.

关键词： poroelastic Compaction Consolidation Gravity Centrifuge Sedimentation Creaming Subsidence Emulsion Dispersion

Evaluation of sample scale effect on geomechanical tests

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Petroleum Research 2022年第4期7卷 527-535页

作者： Maryam Kashfi Saeed Shad Davood Zivar Department of Chemical and Petroleum Engineering Sharif University of TechnologyTehranIran PanTerra Geoconsultants B.V LeiderdorpNetherlands

The size of the rock specimen affects the stress concentrates in the vicinity of the top/bottom of the rock specimen during the evaluation of the geomechanical parameters in the laboratory,which causes un-reliable results.However,the appropriate size for geomechanical evaluation is not well understood yet because of limitations in the sampling and analysis.In this study,a series of numerical simulations using a finite element package was conducted to investigate the effect of sample aspect ratio,fluid saturation,and porosity,on the mechanical behavior of the rock under elastic and poroelastic conditions.In addition,two concepts,stress/strain homogeneity index(SHI)and representative elementary volume(REV),were developed to find out the appropriate sample size.The results show that the presence of stiff platens,which are dissimilar to the specimen material,causes significant stress concentration in the two ends of the specimen.The concentration of stress in the specimen reduces when the aspect ratio increases.An optimum aspect ratio(length-to-diameter equal to 3)was observed by SHI analysis which after that the changes in stress concentration are insignificant.The REV size analysis confirms the obtained optimum aspect ratio by SHI analysis.The saturated specimens show a lower magnitude of stress than applied stress because of the presence of pore pressure,which can carry a portion of the stress.The higher void ratio results in lower strength of the specimen.This study could be beneficial for the better design of geomechanical tests to have reliable results.

关键词： Geomechanics Stress concentration Stress/strain homogeneity index Representative elementary volume(REV) poroelastic Scale dependency