Conference Agenda

This paper presents a case study of the use of piled embankment system with geosynthetic as reinforcement for soft soil subgrade at the Kadusirung Flyover's approach slabs, Banten, Indonesia. The total length of the approach slabs reaches 185 meters with a height of up to 9 meters. The approach slabs’ reinforcement uses a Mechanically Stabilized Earth Wall technology called GSRW (Geoforce Segmental Retaining Wall) system. Geoforce Segmental Retaining Wall is a retaining wall construction that consists of a compacted layer of backfill and has a facing made of precast concrete and reinforced using polyester strip. Geotechnical investigations showed that the area will be constructed upon soft soil subgrade up to a depth of 11 meters. Due to the low bearing capacity and massive settlement the soft soil possesses, the subgrade needs reinforcement. The project with tight schedule requires a subgrade reinforcement that can be installed quickly. Piled embankment with geosynthetic system was then chosen for those reasons. From the results of the design process, the piles underneath the embankment are required to reach a depth of 12 meters with a square mini pile type measuring 25x 25 cm and contiguous bored pile with a diameter of 60 cm under the leveling pad structure. To help transfer the total embankment load to the pile and to consider the soil arching ratio, a combination of small pile cap and high tensile strength geogrid of 175 kN/m was used. From design perspective, the piled embankment system improves the embankment safety factor above the criteria stated in Indonesian National Standard for Geotechnical Design Requirements which is above 1.50 and design with pseudo-static earthquake load which is above 1.10. The system has proven to be easy to implement in the field, fast and can be carried out with good quality control.

<p>The Paper presents a case study demonstrating use of geocells to replace concrete approach slabs and reinforce transition of railway bridge approaches. A bridge across Mindhola River, Surat, India was taken up as a trial. The objective is to gauge the effect of the geocell system to enhance train speeds on the trunk Bombay - Delhi route to 160 kmph.</p>

<p>Presently, issues include frequently damaged concrete approach slabs and differential settlements between the earth embankment and structural bridge with piers often supported on piles or wells. There is a sudden change in stiffness between approach and bridge, and the train speed has to be reduced to avoid unpleasant jerks that cause wear and tear of the rolling stock. Conventionally, concrete approach slabs are provided at transitions which frequently get damaged within maintenance periods and time-consuming to replace. To ensure smooth running of the train at high speeds and with the proposed increase in axle loads, a transition geocell system has been devised which brings about gradual increase in stiffness of the blanket approaching the rigid bridge structure and fosters higher speeds. </p>

<p>Geocells were installed within the blanket layer for the existing track to ensure a smooth transition on either side of the bridge for the same track. Field observations confirmed that the geocells were successful in ensuring a smooth transition of bridge approaches.</p>

<p>Further, geocells proved that by avoiding the conventional concrete slab, there is considerable savings in capital costs and construction time (5 hours of downtime for installation at each side). With this system, the maintenance cycle is extended which not only reduces downtime, but also life cycle costs.</p>

<p>New Zealand experienced a number of large damaging residential and commercial properties. As part of the post disaster recovery, solutions were sought to rebuild on land prone seismically induced liquefaction and associated lateral spreading. NZ is forecast to continue to be subjected to strong seismic shaking. The South Island features a major fault line on its West Coast that has a very high probability of rupture in the next 25 years generating a M8+ event. The North Island features on its entire East Cost a subduction line between the Pacific and Australian Plates that has triggered Mega Thrust Events in the past, with shaking in excess of M9+. </p>

<p>Engineering guidance in NZ, prepared after the Canterbury Earthquake Series, introduced geogrid reinforced gravel crust concept to allow construction of lightweight timber framed buildings. The crust is made by replacing the in-situ soils with high quality geotechnically materials reinforced with multiple layers of geogrids, all wrapped in a geotextile separator to facilitate construction and prevent liquefaction ejecta from penetrating into the reinforced soil body.</p>

<p>This paper will provide the detailed concepts behind the reinforced crust approach, including detailing case studies of structures surviving past repeated severe seismic shaking without major damage. The paper will then extend the concept from residential structures to light commercial and industrial structures; and describe several case studies of completed projects. The paper will describe in detail the design approaches used. It will focus on construction details that are considered essential for successful application of a reinforced crust subject to strong seismic shaking and discuss likely post earthquake performance of buildings on a reinforced crust. Lastly, the paper will provide design details that are provided to ensure that buildings can be returned to full functionality after a major event, including releveling and repairability.</p>

In 1999, the Chelungpu fault in central Taiwan triggered the deadly 921 Chi-chi earthquake, which measured 7.3 on the Richter scale. However, because of specific technical influences, the project reported herein has to pass through the Chelungpu active fault through a high-fill embankment. Due to the fault-induced movement bound to produce severe differential defor-mation and surface rupture, the structure must be earthquake-resistant to ensure its safety. Con-sidering the particular requirements of this section, after exploring several probable solutions, the designers finally determined to apply geosynthetics reinforced soil structure (GRS) to build the reinforced foundation and the reinforced embankment to restrain the differential movement caused by active faults to the greatest extent. The adjacent slopes have also been stabilized carefully. The analysis results show that the safety factors of the GRS embankment and its ad-jacent slopes all meet the requirements of safety and service functions.

<p>The Oosterweel Link project is a new 15km-long motorway connection developed by Lantis for completing the Antwerp ring road R1 (Belgium). It is a major project in Belgium and its design started in the 1990’s to find a solution to the congestion problems in and around Antwerp. The total estimated cost of the project is approximately €4.5bn. The Antwerp ring road is a key part of the Trans-European Transport (TEN-T) Core Network.</p>

<p>Maccaferri collaborated with the design and building of the Mechanically Stabilized Earth (MSE) walls with its main product family „Terramesh“. This is a well-known system used in Europe and in the rest of the world to support or enable the construction of infrastructures in tight urban corridors, forming retaining walls, road embankments, wing walls and bridge abutments known as Geosynthetic Reinforced Soil-Integrated Bridge Systems (GRS-IBS). „Terramesh“ double twist steel wire mesh reinforcements have been used in combination with ParaLink^® and Paragrid^® geogrids representing an evolution and a significant advantage for both cost-effectiveness and performance. The project includes 15.000 facing sqm of „Terramesh Green^®“, 14.000 facing sqm of „Terramesh Mineral^® and System^® and 5.000 facing sqm of gabion cladding. During 2020, 6.000 sqm of MSE walls have been already installed with a maximum height of 6.5m for the structures erected so far. The Terramesh products can be either with a stone mineral facing or a green facing, according to the architectural plan: in Oosterweel for architectural reasons, most of the structures present a stone facia.</p>

<p>The MSE walls have been designed according to Eurocodes and NBN EN 1997-1 ANB (National Annex for Belgium). The MSE wall facings present a tilt from 5 up to 10 degrees from the vertical. The next years will face new challenges with MSE walls up to 17m in height and 85° of facing inclination.</p>

<p>Due to the restriction of the perimeters with good foundation lands in Bucharest, which are also very expensive, a need arose to base on fillings, especially for residential complexes and some low-rise buildings. Although these houses transmit lower pressures to the foundation lands, due to the inhomogeneity of the fillings, differentiated settlements appear, which in the end can destroy the building. Consequently, in addition to the well-known solution to completely remove fillers - a solution that involves excavation work, transportation, storage in specially designed spaces, activities that require approvals, environmental protection work, high costs - Geostud specialists have found alternative technologies consolidation and stabilization of these fillers, based on the use of geosynthetics.</p>

<p>The article presents the technologies, including the theoretical basis and examples of works where they have been used.</p>

<p>Geogrid reinforced mechanically stabilised earth (MSE) structures have been applied extensively worldwide, and the advantages in both technical and economical feasibility have been documented and demonstrated in numerous projects. This project case study describes the design and construction the 23 MSE walls at the Pokuase Interchange Project in the Accra region (Ghana). The wall heights varied up to approximately 10m. The walls are supporting the approach embankments of various fly-over bridge structures at the Interchange. It concerned a first application of this technology in Ghana, and it was executed successfully within 2 years time. The vertical MSE structures were finished with prefabricated concrete panels as a protective facing, which were placed after construction of the wrap-around geogrid reinforced walls. Local granular fill could be used in the structures. The design and construction was performed in accordance with international standards (BS8006, EBGEO, EN 14475). The design included a stability anaysis, consolidation and settlement analysis, and a detailed Method Statement. Intensive training of the contractor and regular expert supervision supported the proper execution of the works by the contractor.</p>

<p>The construction of geosynthetic-reinforced soil retaining walls with a staged-constructed full-height rigid facing for railways, including high-speed train lines, roads and other retaining walls began to be used in Japan in the late 1980s. After the wrap-around type geosynthetic reinforced soil wall is constructed, the front face is covered by a cast-in-situ reinforced concrete wall. The earthquake performance of these walls is extremely high and is economical compared to classical retaining structures. This system was used in a slightly different way on the reinforced concrete wall of an industrial building in Bursa, a city located in the first degree seismic zone of Turkey. The 10m high reinforced concrete wall was staged-constructed in three parts using the prefabricated modular double-wall system, while the backfill was reinforced with geogrids. In this paper, the effect of using a geogrid-reinforced fill and unreinforced fill on the calculation of the reinforced concrete wall section is compared, and the details of the system and its construction are discussed.</p>

The Duqm area in the Central Eastern Oman is located 600km southwest of Muscat, the capi-tal city of Sultanate of Oman. Extensive developmental projects like seaport, airport, dry dock, oil refinery, crude oil storage terminals, infrastructure like roads, railway, bridges, factories, buildings, and residential villas etc. are under construction or on the anvil. The Duqm area is marked by the significant presence of ‘soft sabkha’ soil which drastically influences the con-struction of foundations for civil engineering structures in that area. Generally, soil having low undrained shear strength is often referred to as ‘soft soil’. Construction of embankments on soft soil can be critical because they have low strength and high compressibility. Since such soils have low permeability, the failure happens at an undrained condition within a short period after the embankment construction. ‘Sabkha’ is an Arabic expression to describe a type of soft soil with high salt content and are characterized by low bearing capacity and low SPT values. Sabkha soils are widely distributed in the Arabian Peninsula. Generally, for sabkha soil having SPT value less than 5 in muddy conditions, the first and foremost conventional solu-tion of ground improvement adopted by designers for road projects in the Middle East region is provision of stone columns below the road embankment for total depth of soft soil. High strength geosynthetic layers can be used as basal reinforcement for the construction of em-bankments over soft soils, satisfying the stability criteria laid by the international standards like BS 8006: 2016. Unidirectional high tensile strength geogrids like Paralink is well suited for basal reinforcement applications in Sabkha soil. Depending on the type and magnitude of expected settlement of foundation sabkha soil, this technique can be adopted replacing the conventional deep ground improvement solutions, for most of the cases. Through the case reference of basal reinforcement technique application for Duqm roads project in Oman, this paper briefly outlines the problems associated with the design and construction of embankments over soft sabkha soil commonly found in the Arabian Peninsula and the application of geosynthetic materials as basal reinforcement for stabilizing such embankments, avoiding time consuming and expensive deep ground improvement techniques generally adopted by the road designers.

Globally temporary working platforms are an underrated element of almost every con-struction site. Geogrids have been installed in the temporary working platforms for dec-ades now, as they offer contractors large cost, time and carbon savings compared to alter-native solutions. The use of hexagonal, multiaxial stabilisation geogrids and square, biaxial geogrids is by far the most common method for the cost-effective solutions. However, de-signing temporary working platforms using geogrids constitutes a challenge, as broadly available methods (e.g. BR470) present a conservative approach for incorporating ge-ogrids in the designs that results in non cost effective solutions. Moreover, geosynthetics manufacturers methods are validated only for specific manufacturers products (e.g. 45° load spread or T-value method). This paper discusses the importance of temporary work-ing platforms design methods full scale validation and lists ideal site conditions for full scale validation tests. Also, it reviews recently undertaken site tests that aimed at testing temporary working platforms full bearing capacity and examining the design methods.