A plane strain yield design approach to stability analysis of a column‐reinforced soil foundation under inclined loading

Summary This paper presents a numerical study of high strength concrete microstructure effects on its uniaxial and biaxial compressive strengths. Concrete is first represented as a set of angular aggregates interacting within a cement paste matrix. Then, a yield design kinematic approach is conducted at the mesoscopic scale in order to determine the concrete compressive strength for a given loading path. The proposed model, having a low computational cost, is able to capture the main microstructure effects already observed in literature on concrete uniaxial compressive strength, in particular, the aggregates volume fraction and maximal size effects. Finally, the proposed model also predicts the biaxial failure envelope of high strength concrete and confirms some experimental trends observed in literature.

“…Let us assume that each one of them is animated with a virtual rigid body movement and denote respectively

{\underset{false¯}{\overset{U}{true}}}^{i} = ((),,, {\overset{U}{true}}_{x}^{i}, {\overset{U}{true}}_{y}^{i}, {\overset{U}{true}}_{z}^{i})

and

{\underset{false¯}{\overset{W}{true}}}^{i} = ((),,, {\overset{W}{true}}_{x}^{i}, {\overset{W}{true}}_{y}^{i}, {\overset{W}{true}}_{z}^{i})

the displacement and the rotation velocities of a given Voronoï particle i according to a Cartesian base

((),,, \underset{false¯}{e_{x}}, \underset{false¯}{e_{y}}, \underset{false¯}{e_{z}})

. The yield design kinematic approach states that if a macroscopic bearable loading is applied on the concrete specimen boundaries, all kinematically admissible virtual movements

\underset{\overset{false^}{U}}{true} = ((), {\underset{false¯}{\overset{U}{true}}}^{i}, {\underset{false¯}{\overset{W}{true}}}^{i})

with ( i ∈ [1, N ]) must verify the following condition:

P_{e} (\underline{\hat{U}}) \leq P_{rm} (\underline{\hat{U}})

with

P_{e} ((), \underset{false¯}{\overset{U}{true}})

and

P_{rm} ((), \underset{false¯}{\overset{U}{true}})

are respectively the external loading power and the maximum resisting power associated to

\underset{\overset{false^}{U}}{true}

.…”

Section: The Yield Design Kinematic Modelmentioning

confidence: 99%

Section: The Yield Design Kinematic Modelmentioning

confidence: 99%

Numerical study of the biaxial compressive strength of high strength concrete based on a yield design micromechanical approach

Naija

Hassen

Limam

et al. 2020

“…Most of the problems mentioned above arise from a soft subgrade. A variety of ground improvement techniques have been adopted to address soft subgrade‐related issues, among others: grouting [eg,], soil mixing [eg,], micropile [eg,], soil nail [eg,], stone column [eg,], and rigid inclusions . The last one (also known as column‐supported embankment) are gaining more attention every time in geotechnical engineering in general [eg,], and in the railroad industry in particular [eg,].…”

Section: Introductionmentioning

confidence: 99%

“…Railroads issues associated with shrink/swell soils are discussed in detail in Sanchez et al 21 Most of the problems mentioned above arise from a soft subgrade. A variety of ground improvement techniques have been adopted to address soft subgrade-related issues, among others: grouting [eg, [22][23][24][25] ], soil mixing [eg, [26][27][28][29] ], micropile [eg, [30][31][32] ], soil nail [eg, [33][34][35][36] ], stone column [eg, [37][38][39][40], and rigid inclusions. [41][42][43][44][45][46][47][48][49][50][51][52] The last one (also known as column-supported embankment) are gaining more attention every time in geotechnical engineering in general [eg, [53][54][55][56][57][58][59][60][61], and in the railroad industry in particular [eg, [62][63][64][65]…”

Section: Introductionmentioning

confidence: 99%

Numerical study on the effect of rigid inclusions on existing railroads

Wang

Sánchez

Briaud

2019

Summary Railroad track problems have been exacerbated by the continuous increase in freight loads and train traffic. The need to implement soil improvement technique in a relatively short window‐time (ie, to minimize train‐traffic disruption) is a key aspect to be considered when adopting a convenient remedial solution to control settlements in railroads constructed on problematic subgrades. Rigid inclusions are selected in this paper because they are reliable solutions relatively easy to implement. Furthermore, they can be used in different ground conditions and are suitable for short construction times (eg, do not require a curing time, as in grouting methods). Typical (analytical) methods for the design of rigid inclusions are adopted in this paper to define an optimal distribution of piles for the case of existing railroads. The selected layout is then analyzed in detail by means of a 3‐D dynamic finite element simulator using both, elastoplastic and elastic models. The performance of rigid inclusions is studied considering different operational scenarios, with dynamic and static loads, as well as involving subgrades with different plasticity index values. It is found that the predictions from the analytical design methods for rigid inclusion tend to be unconservative when compared against the finite element results. As for the numerical solutions, the most unfavorable stress condition is associated with the dynamic elastoplastic finite element solution. It is estimated that the rigid inclusions will contribute to a reduction in the ground settlements of around 15% to 20%, depending on the subgrade plasticity index.

A plane strain yield design approach to stability analysis of a column‐reinforced soil foundation under inclined loading

Arévalos

Maghous

2016

Self Cite

The ultimate bearing capacity problem of column-reinforced foundations under inclined loading is investigated within the framework of static and kinematic approaches of yield design theory. The configuration of a native soft clayey soil reinforced by either a group of purely cohesive columns (lime-column technique) or a group of purely frictional columns (stone-column technique) is analyzed under plane strain conditions. First, lower bound estimates are derived for the ultimate bearing capacity by considering statically admissible piecewise linear stress distributions that comply with the local strength conditions of the constitutive materials. The problem is then handled by means of the yield design kinematic approach of limit analysis through the implementation of several failure mechanisms, allowing the formulation of upper bound estimates for the ultimate bearing capacity. A series of finite element limit load solutions obtained from numerical elastoplastic simulations suggests that the predictions derived from the kinematic approach appear to be more accurate than the estimates obtained from the static approach. Comparison with available results obtained in the context of yield design homogenization demonstrates the accuracy of the proposed direct analysis, which may therefore be viewed as complementary approach to homogenization-based approaches when a small number of columns is involved. Figure 13. Effect of cohesion ratio m = C r /C s on the lower and upper bound estimates of the ultimate bearing capacity for 'Lime-cement columns ' configuration. [Colour figure can be viewed at wileyonlinelibrary.com]