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Abstract The Mohr-Coulomb failure criterion, which is typically used to represent soil strength, has been found to overestimate the tensile strength of most soils. Considering this fact, the concept of tensile strength cut-off was adopted to reduce or eliminate the tensile strength from the criterion. Based on that concept, this study proposes a kinematical framework for the estimation of active earth pressure on retaining structures in cohesive backfills. According to the associative flow rule, a valid rotational collapse mechanism is established. The resultant active earth pressure is determined from the work rate balance equation and is expressed as a dimensionless active earth pressure coefficient. The proposed approach is validated by a numerical simulation. Design charts are presented for a parametric study and for simple use in engineering. The results show that the presence of soil cohesion has a favorable influence on the stability of retained soil masses. Accounting for the impact of tension cut-off leads to a more conservative result, and this impact tends to be more obvious with the increase of cohesion. Finally, the assumptions that were made about the validity of the associative flow rule and the action point of the resultant earth pressure are discussed. [ABSTRACT FROM AUTHOR]

Experimental results of a series of laboratory pullout tests on a new screw soil nail are presented. A review of the literature for the screw soil nails as well as a comparison of its performance with other conventional types of soil nails is discussed. The present investigation also examines the fundamental interface mechanism and attempts to define the associated rupture zones in cohesionless material with the aid of thin vertical bands of coloured sand cast in a large distinctly fabricated pullout box. The philosophy behind the design and development of the new screw nail is briefly described first followed by presentation of the laboratory testing procedure and its instrumentation. The results of the testings indicate that the slip mechanism, which controls the pullout behaviour, is rather different to the conventional soil nails and the resultant pullout capacity is higher when compared to this type soil nails. This effect is attributed to the geometry of the screw nail and the installation processes that result in the development of different soil stresses around the soil nail. In addition, the experimental pullout results demonstrate, contrary to the conventional soil nail, that the screw nail pullout capacity is dependent on the overburden pressure and that the failure planes extends out a certain radial distance from the soil–nail interface. From the test results, it is shown that the failure of the screw nail satisfies the Mohr–Coulomb failure condition, which is similar behaviour seen in the conventional soil nail tests. [ABSTRACT FROM AUTHOR]

Abstract: Finite Element (FE) pseudo-static analysis can provide a good compromise between simplified methods of dynamic analysis and time domain analysis. The pseudo-static FE approach can accurately model the in situ, stresses prior to seismic loading (when it follows a static analysis simulating the construction sequence) is relatively simple and not as computationally expensive as the time domain approach. However this method should be used with caution as the results can be sensitive to the choice of the mesh dimensions. In this paper two simple examples of pseudo-static finite element analysis are examined parametrically, a homogeneous slope and a cantilever retaining wall, exploring the sensitivity of the pseudo-static analysis results on the adopted mesh size. The mesh dependence was found to be more pronounced for problems with high critical seismic coefficients values (e.g. gentle slopes or small walls), as in these cases a generalised layer failure mechanism is developed simultaneously with the slope or wall mechanism. In general the mesh width was found not to affect notably the predicted value of critical seismic coefficient but to have a major impact on the predicted movements. [Copyright &y& Elsevier]

Abstract: This paper examines the seismic response of a large and complex system comprising a Lock chamber and three neighbouring water saving basins (WSBs). The developed two-dimensional plane strain finite element model included the entire system in order to explore the interaction of the various structures. The first set of analyses was undertaken under static conditions to simulate the construction sequence and to establish the stress regime prior to the examined seismic event. Subsequently, dynamic time domain analyses were performed to examine the response of the system to seismic loading. The ground motion was applied into the finite element mesh employing a sub-structuring technique which enables economic modelling of large computation domains and accurate representation of the semi-infinite half-space. The paper explores some aspects of the numerical modelling of such complex systems, such as the impact on the predicted seismic response of the adopted constitutive model and the modelling of hydrodynamic effects. The discussion of the dynamic analyses results focuses on the main Lock structure, looking at the prevailing modes of deformation, the potential lift-off of the base of the Lock walls and the interaction of the main wall with the other retaining structures. [Copyright &y& Elsevier]

Abstract: A methodology for the probabilistic analysis of reinforced concrete cantilever walls is developed and described in this paper. The wall’s external stability under static conditions is addressed and modeled as a series system with correlated failure modes. Computations of reliability are performed using Monte Carlo simulations for assumed probability distributions of the backfill and foundation material engineering properties. A case example is analyzed based on the described methodology. The results indicated that risk, measured by the system probability of failure, is not a linear function of safety ratios. All three safety ratios in question were positively correlated, with bearing capacity being subjected to higher degree of uncertainty. The degree of correlation was found to have an important effect on the system probability of failure. Considering the width of the base as varying design parameter, the study also showed that first-order reliability bounds, which are often applied in practice, may lead to a noteworthy over- or under-estimation of the design. [Copyright &y& Elsevier]