Conference Agenda

In a severe level of seismic design (so-called Level2 such as 1995 Kobe and 2011 Tohoku in Japan), the performance of the road that tolerates some deformation which can be re-stored easily is allowed. The authors have conducted two approaches in this paper. One is to verify the effect of the countermeasure using geosynthetics sandwiched with gravel layers beneath the embankment in Level2 event by experiment and dynamic analyses. The other is to verify the amount of deformation after a Level1 (180 gal) seismic by numerical simulations. The experiment and both Levels of seismic stage of numerical simulation results show the effectiveness of the countermeasures.

<p>Shallow foundations are sometimes built on geosynthetic mechanically stabilized earth (MSE) structures. Such structures are extensively used to support bridge loads and to form approach roads. In recent years many studies provided chart-based solutions to calculate the ultimate bearing capacity of the foundations of MSE structures. Such solutions are provided for different combinations of geotechnical and geometric input parameters. However, such design charts cannot be implemented as part of automated workflows as they contain curves that need to be used on a case-by-case basis. This paper presents a novel method to calculate the seismic bear-ing capacity of a shallow foundation positioned on the crest of a geosynthetic reinforced soil structure. Such approach is based on a predictive mathematical expression that can be readily used and implemented as part of performance-based design approaches. It relies upon a data-base of solutions obtained using the upper-bound limit analysis. The proposed expression is valid for static and seismic conditions. Examples are presented illustrating the implementation of this method as part of design procedures of selected foundation systems.</p>

<p>Large earthquakes occurring worldwide regularly renew the interest in the analysis of the post-seismic serviceability of Geosynthetic Reinforced Soil Walls (GRSWs). Specifically, several well-documented case histories show that, differently from other types of retaining wall, GRSWs have generally exhibited a satisfactory performance characterized by a ductile behavior against earthquake-induced deformations. Similarly, experimental data concerning reduced-scale physical models (shaking table and centrifuge tests) emphasize the satisfactory seismic performance of these geotechnical systems.</p>

<p>In this vein, a simplified displacement-based predictive model, aimed to the evaluation of the seismic performance of GRSWs in terms of magnitude of seismic-induced permanent displacements, was proposed in the framework of a joint research activity carried out by the Mediterranea University of Reggio Calabria and University of Messina. Using the results of large parametric analyses, the main peculiarities of the seismic performance of GRSWs are discussed in the paper focusing on the relevant role of the amplification phenomena in the reinforced soil mass, the soil-reinforcement cyclic interaction and the reinforcement ductility. Using a set of properly selected input ground motions, all these influences have been investigated and discussed focusing on the influence of the possible coupling (between the frequency content of the input motion and the vibration frequencies of GRSWs) and accounting for the crucial effect of the soil-geosynthetic cyclic interaction which significantly affect the post-seismic serviceability conditions.</p>

Retaining wall structures are widely used in different civil engineering projects including building construction, highways, railways, harbors, and many other projects in order to resist the lateral pressure of soil and water. In the last years, Expanded Polystyrene (EPS) geofoam has been used to construct earthquake resilient infrastructure in seismic areas because of its extremely low density and high compressibility when compared with the traditional backfill materials. The use of EPS geofoam backfill behind retaining and buried structures also limits the horizontal forces that can develop during earthquakes. In earthquake prone areas, retaining walls should be designed to resist the seismic increment of earth pressures in addition to static loads. The use of EPS geofoam backfill behind retaining and buried structures also limits the horizontal forces that can develop during earthquakes. In this study, the effects of using EPS geofoam backfill on the reduction of lateral earth pressure and increasing of seismic stability of retaining wall under different earthquake motions were determined by comparison of the numerical model with geofoam backfill with the model with cohesionless backfill. A series of numerical analyses were performed by a finite element analysis program, Plaxis software. A parametric analysis was performed to evaluate the effectiveness of inclusion of Geofoam backfill considering the effects of the density of Geofoam and earthquake characteristics. Numerical simulations with two different conventional backfills and Geofoam material with the different densities are compared. The results of the comparative study showed that the effectiveness of the Geofoam backfill on the seismic performance of the retaining wall is highly dependent on the density of the Geofoam and characteristics of the earthquake motions.

<p>The main objective of this paper is to study the influence of different engineering parameters on the behavior of reinforced bridge abutments subjected to seismic excitations. In this study, the Founders/Meadows reinforced bridge abutment in Denver Colorado was considered as a case study. In the previous numerical simulations and studies conducted on the same bridge, base isolator was not considered in the model between deck and the deck footing. However, the new model is comprised of two abutments, one pier in mid-span, concrete deck, and base isolators connecting deck to deck footing. Numerical modeling was carried out by using finite difference code FLAC v7.0.</p>

<p>A number of analyses with different parameters were carried out to evaluate their influences on seismic behavior of the GRS bridge abutment. The studied parameters mainly belong to base isolator, foundation soil, reinforced soil, and input ground motion. Horizontal displacement of facing as well as rotation of deck footing are selected as the main seismic excitations outputs. The overall results show that the response of the two-abutment model with the base isolator is significantly dependent on the base isolator damping, strength of foundation as well as reinforced soils, and frequency of input acceleration wave. The overall response of the GRS bridge abutment subjected to seismic excitations is evaluated and discussed.</p>

<p>Geosynthetic composite systems are extensively used in liner system which are placed beneath the landfill to isolate waste material from the surrounding environment but the geosynthetics can also be the weak interface, so analysis of seismic response and permanent deformation of landfill should be performed considering the influence of liner interface. This paper investigates the contributing role of the base liner on the seismic behavior of landfills.</p>

<p>Based on the results of the site investigation, dynamic analysis of a typical landfill in Italy was carried out with finite difference code FLAC 2D.</p>

<p>The displacement of the geosynthetics resulting from the seismic loading has estimated along with the potentially induced seismic slip surface taking place on the interfaces. Results indicate that the geosynthetic liner system affects the dynamic response of landfill and the seismic displacements on the geosynthetics should not be neglected.</p>

<p>The paper discusses the results and implications on seismic design of landfills to ensure the integrity of the lining systems as well as the stability of the waste landfill.</p>

<p>An extreme case of model geosynthetic-reinforced soil wall failure encountered during shaking table testing is described in this paper. A ¼ scale, 2 m high model wall with concrete block facing and geotextile reinforcement length of 85 cm, the wall was brought to collapse under dynamic loading in which the maximum shaking table acceleration reached almost 2g. Failure started with the upper facing blocks falling and continued with overturning of the wall face. The test was terminated before the wall fully collapsed. In this paper, the failure mechanism is investigated and the performance of the model is compared to that predicted by design recommendations. The stiffness of geotextile layers and the silt content of the fill are suggested as the reason for the good performance up to such large dynamic loads.</p>

This paper presents the assessment of the adequacy of a Mechanically-Stabilized Earth (MSE) wall, reinforced with steel geostraps, for a bridge approach within Metro Manila, located few kilometers away from the active West Valley Fault (WVF). Performance of the MSE Wall un-der static and seismic conditions were assessed using two approaches: (1) Limit Equilibrium Method (LEM) by GLE/Morgenstern-Price Method; and (2) Deformation Analysis by Finite Element Method (FEM). The study demonstrates that while inadequate factors of safety under seismic loading may be obtained using LEM, earthquake-induced deformation values are found to be within tolerable limits for lower-hazard design levels. It was also established that designing the geostrap reinforcement to fully withstand higher-hazard ground motions may be uneconomical for the available wall material. Nevertheless, cost-effectiveness of the design may also be achieved by allowing some deformation to the structure in case of higher-level earthquakes, while maintaining serviceability in keeping with current seismic design philosophy.

According to the circular economy and sustainable growth, the need for low-cost seismic isolation systems has led to proposals of new projects. The use of granular soils mixed with granulated rubber derived from scrap tires as a layer underlying the foundations of structures is emerging as a new isolation technique. It represents a solution for the mitiga-tion of seismic risk and the management of waste tires.

Only a few experimental studies on this subject are available in the literature, and they are limited to small-scale testing. In the Project SOFIA-3rd call of the SERA-H2020-INFRAIA-2016-2017/H2020-INFRAIA-2016-1 European Research Program, the first experimental campaign on a full-scale prototype structure founded on different gravel-rubber mixtures (GRM) was carried out. The GRMs had variable rubber content per weight (0%, 10%, 30%, labelled as GRM 100/0, GRM 90/10, and GRM 70/30, respectively). The experimental in-vestigation included ambient noise, free- and forced-vibration tests.

This paper shows the results achieved during the forced-vibration tests on the systems with GRM 100/0 and GRM 70/30 and the results obtained by a non-linear 3D FEM model-ling of these tests.

The comparison between the experimental and numerical results allowed us to investigate the isolation capacity provided by GRMs and the effects of the rubber content per weight.

Compared with rigid retaining systems, mechanically stabilized earth (MSE) walls offer various advantages, such as their cost competitiveness and a higher tolerance for deformations under earthquake loads. Accordingly, MSE walls have become widely popular in the last decades and a thorough understanding of their static and seismic behavior is required for advances in design. In this study, the effect of reinforcement stiffness on the static and seismic response of an MSE wall was investigated by performing two-dimensional finite element analyses. The MSE wall models were excited with a harmonic loading with a frequency content of 4 Hz. In the analysis, geogrids were modeled with two axial reinforcement stiffness values: 600 kN/m and 1200 kN/m. Relative horizontal displacements along the wall height, displacement along the reinforcements, and tensile loads in the geogrids were investigated. The results indicated that the effect of reinforcement stiffness on the MSE wall displacements was less pronounced in the static condition compared with the seismic condition. MSE wall displacements were more visible at about mid-height of the wall in the static case. In the seismic case, the increase in reinforcement stiffness caused a horizontal displacement reduction along the wall height. Doubling the axial reinforcement stiffness increase caused a visible increase in the reinforcement axial forces, in the mid to lower reinforcement levels in the seismic case.

<p>The Kretek II Bridge located in Bantul, Yogyakarta Special Region (DIY) is part of the Java Southern Cross Road (JJLS) project that connects Samas-Kretek and Kretek-Parangtritis. The location of this bridge is in an earthquake potential area and is on an active fault line that crosses the embankment wall of the bridge (abutment area). According to research by several experts, based on the direction of movement, the Opak fault is included in normal faults, namely faults that occur due to the maximum compressive force in the vertical direction, causing one of the rock planes to move downward following the fault plane. The Opak fault line is expected to cross one side of the bridge wall. GSRW (Geoforce Segmentall Retaining Wall) is an MSEW system that will be used for the construction of the bridge wall located on the fault line. Geoforce Segmental Retaining Wall is a retaining wall construction consisting of a compacted layer of an embankment and has a facing made of precast concrete and reinforced using polyester strip. In the case of this project, GSRW is installed into 3 segments which were separated by dilated concrete. The purpose of segment’s division is to reduce the damage that will occur to the abutment if there is movement due to faults. Segment 2 or middle segment is the area crossed by the fault line and spaced up to a dozen meters from the line. Although the displacement distance and the magnitude of the plane caused by the fault cannot be predicted, the GSRW construction is expected to reduce the damage that will occur, because this system can move independently (behaving like a puzzle) so that the concrete panels are more flexible against earthquakes or shocks.</p>