A Numerical Study of the Installation-Induced Stresses and Excess Pore-Water Pressures around Rigid Inclusions Using a Linear-Elastic Perfectly-Plastic Soil

IFCEE 2015 ◽  
2015 ◽  
Author(s):  
Alfonso J. Rivera ◽  
C. Guney Olgun ◽  
Thomas L. Brandon ◽  
Frederic Masse
Keyword(s):  
Pore Water ◽  
Numerical Study ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Pore Water Pressures ◽  
Induced Stresses ◽  
Elastic Perfectly Plastic ◽  
Excess Pore

Effect of drainage and sequential filling on the behavior of backfill in mine stopes

2014 ◽  
Vol 51 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Nawfal El Mkadmi ◽  
Michel Aubertin ◽  
Li Li
Keyword(s):  
Pore Water ◽  
Numerical Study ◽  
Water Drainage ◽  
Filling Rate ◽  
Mining Operations ◽  
Overburden Pressure ◽  
Filling Sequence ◽  
Pore Water Pressures ◽  
Backfilled Stopes ◽  
Excess Pore

Underground backfilling offers significant economic and environmental advantages to mining operations. There is however a limited knowledge and understanding of how the backfill behaves within mine stopes, which creates some concern regarding the risk of accidents with potentially serious consequences. It is thus important to investigate further the response of backfill to ensure safe working conditions and optimize the filling sequence. This paper presents key results from a numerical study aimed at analyzing the hydrogeotechnical response of backfill in a narrow vertical stope. The simulations illustrate how stresses are influenced by stope geometry, water drainage, and filling rate. Three main cases are presented here to illustrate these effects; namely, (i) simulation of dry (or drained) backfill, (ii) a rapidly filled stope with progressive drainage and consolidation, and (iii) sequential backfill placement with different filling rates. The third case includes a simulation with evolving properties due to the binder added to the backfill. The results from the numerical analyses show that arching effects develop within narrow backfilled stopes because of the stiffness contrast between the rock and the fill material. This can produce a significant reduction of the stresses (horizontal and vertical) in comparison with the overburden pressure. The simulation results also show the development of excess pore-water pressures after the placement of the saturated backfill within the stope. Drainage tends to reduce these pressures and increase the frictional stresses along the rock walls. The sequentially filled stope simulations show that a rapid filling rate produces much higher total stresses and excess pore-water pressures, compared to slower rates. The simulation of the cemented backfill, with evolving properties, indicates that the progressive changes can have a significant effect on the total and effective stresses in the stope. A discussion follows on the implications of these results.

scholarly journals A FEM analysis of the settlement of a tall building situated on loess subsoil

2020 ◽  
Vol 10 (1) ◽  
pp. 519-526
Author(s):  
Krzysztof Nepelski
Keyword(s):  
Fem Analysis ◽  
Actual Process ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Modified Cam Clay ◽  
Linear Behaviour ◽  
Subsequent Calculation ◽  
Elastic Perfectly Plastic ◽  
Subsoil Model ◽  
Storey Building

AbstractIn order to correctly model the behaviour of a building under load, it is necessary to take into account the displacement of the subsoil under the foundations. The subsoil is a material with typically non-linear behaviour. This paper presents an example of the modelling of a tall, 14-storey, building located in Lublin. The building was constructed on loess subsoil, with the use of a base slab. The subsoil lying directly beneath the foundations was described using the Modified Cam-Clay model, while the linear elastic perfectly plastic model with the Coulomb-Mohr failure criterion was used for the deeper subsoil. The parameters of the subsoil model were derived on the basis of the results of CPT soundings and laboratory oedometer tests. In numerical FEM analyses, the floors of the building were added in subsequent calculation steps, simulating the actual process of building construction. The results of the calculations involved the displacements taken in the subsequent calculation steps, which were compared with the displacements of 14 geodetic benchmarks placed in the slab.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

A new approach to the stability analysis of thawing slopes

1980 ◽  
Vol 17 (4) ◽  
pp. 607-612 ◽  
Author(s):  
Luis E. Vallejo
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water ◽  
Active Layer ◽  
Necessary Conditions ◽  
Mass Movements ◽  
New Approach ◽  
Pore Water Pressures ◽  
The Stability ◽  
Excess Pore

A new approach to the stability analysis of thawing slopes at shallow depths, taking into consideration their structure (this being a mixture of hard crumbs of soil and a fluid matrix), is presented. The new approach explains shallow mass movements such as skin flows and tongues of bimodal flows, which usually take place on very low slope inclinations independently of excess pore water pressures or increased water content in the active layer, which are necessary conditions in the methods available to date to explain these movements.

Analytical Solutions of Crack Tip Plasticity Zone Shape for a Semi-Infinite Crack

2003 ◽  
Author(s):  
Peihua Jing ◽  
Tariq Khraishi ◽  
Larissa Gorbatikh
Keyword(s):  
Plane Strain ◽  
Plane Stress ◽  
Analytical Solutions ◽  
Yield Criterion ◽  
Plasticity Zone ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Classical Plasticity ◽  
Elastic Perfectly Plastic ◽  
Von Mises

In this work, closed-form analytical solutions for the plasticity zone shape at the lip of a semi-infinite crack are developed. The material is assumed isotropic with a linear elastic-perfectly plastic constitution. The solutions have been developed for the cases of plane stress and plane strain. The three crack modes, mode I, II and III have been considered. Finally, prediction of the plasticity zone extent has been performed for both the Von Mises and Tresca yield criterion. Significant differences have been found between the plane stress and plane strain conditions, as well as between the three crack modes’ solutions. Also, significant differences have been found when compared to classical plasticity zone calculations using the Irwin approach.

scholarly journals Experiment Study of Lateral Unloading Stress Path and Excess Pore Water Pressure on Creep Behavior of Soft Soil

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Wei Huang ◽  
Kejun Wen ◽  
Dongsheng Li ◽  
Xiaojia Deng ◽  
Lin Li ◽  
...  
Keyword(s):  
Pore Water ◽  
Creep Behavior ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Stress Path ◽  
Deviatoric Stress ◽  
Excess Pore Water Pressure ◽  
Pore Water Pressures ◽  
Excess Pore

The unloading creep behavior of soft soil under lateral unloading stress path and excess pore water pressure is the core problem of time-dependent analysis of surrounding rock deformation under excavation of soft soil. The soft soil in Shenzhen, China, was selected in this study. The triaxial unloading creep tests of soft soil under different initial excess pore water pressures (0, 20, 40, and 60 kPa) were conducted with the K0 consolidation and lateral unloading stress paths. The results show that the unloading creep of soft soil was divided into three stages: attenuation creep, constant velocity creep, and accelerated creep. The duration of creep failure is approximately 5 to 30 mins. The unloading creep behavior of soft soil is significantly affected by the deviatoric stress and time. The nonlinearity of unloading creep of soft soil is gradually enhanced with the increase of the deviatoric stress and time. The initial excess pore water pressure has an obvious weakening effect on the unloading creep of soft soil. Under the same deviatoric stress, the unloading creep of soft soil is more significant with the increase of initial excess pore water pressure. Under undrained conditions, the excess pore water pressure generally decreases during the lateral unloading process and drops sharply at the moment of unloading creep damage. The pore water pressure coefficients during the unloading process were 0.73–1.16, 0.26–1.08, and 0.35–0.96, respectively, corresponding to the initial excess pore water pressures of 20, 40, and 60 kPa.

scholarly journals A SEMI-ANALYTICAL SOLUTION FOR CONSOLIDATION AROUND A SPHERICAL CAVITY IN AN ELASTO-PLASTIC MEDIUM AND ITS POTENTIAL APPLICATION FOR TUNNELING

2014 ◽  
Vol 11 (02) ◽  
pp. 1342010 ◽  
Author(s):  
A. S. OSMAN ◽  
M. ROUAINIA
Keyword(s):  
Analytical Solution ◽  
Pore Water ◽  
Spherical Cavity ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Contraction Theory

An analytical solution for consolidation around spherical cavity contraction is developed. This solution has the potential to evaluate consolidation around tunnel heads. The initial excess pore water pressure immediately after the creation of the cavity is estimated from the cavity expansion/contraction theory using a linear-elastic-perfectly-plastic soil model. Expressions for the decay of pore water pressure with time are obtained using elasticity. Curves showing the variation of pore water pressure with time are plotted in nondimensional form. Comparison with two-dimensional coupled stress-pore pressure finite element analysis shows that the proposed semi-analytical solution can successfully predict the poro-elasto-plastic behavior around spherical cavity.

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