ABSTRACT: Soil nailing is an in-situ reinforcement technique that has been widely used in the stabilisation of slopes and excavations by retaining in-situ soils with metallic bars or relatively small fully bonded inclusions. Soil nails are normally subjected to tension, shear forces and bending moments across the potential soil slip planes, between the active and stable zones. Field measurements were made on the lateral deflection of the wall supported by driven steel tubes and soil deformation parameters were back analysed. This paper is an attempt to investigate the possible working mechanism using finite element analyses and the significance of bending stiffness of soil nails in an excavation in soft residual soils. Finite element analysis and measured field data indicated that bending moment has a significant role in restraining the lateral displacement of the wall during the excavation process and possibly at its ultimate limit state as well. The outcome of this investigation is that lateral bending has significant effects as the reinforced soil approaches failure and analytical procedures developed should accurately mimic the progressive change in the working mechanisms. INTRODUCTION The use of soil nailing in excavations and slope stabilisation has gained wide acceptance in Southeast Asia, specifically in Malaysia and Singapore due to its effectiveness and huge economic savings. With various development schemes on-going in this region, this method has been extensively used in areas where the soil type is compatible with soil nailing such as residual soils and stiff cohesive soils of low plasticity. Recommendations Clouterre (1993) cautioned the use of soil nailing in soils containing high quantities of clay where moisture content might increase after construction. These restraints is based on the thinking that soft soils will creep significantly over long term and decreased in pullout resistance.

ABSTRACT: This study aims at making the reference table of the mix design in accordance with the required design specifications for the soilcrete made of FGC stabilizing agent by using the statistical experiment method. FGC stabilizing agent is the optimized mixtures of F ly ash, G ypsum and C ement for the ettringite hydrates which is effective for early stabilization of unconsolidated soil. The treated soil is the clay which are widely found here and there in Korea. As the results of this study we could derive the practical reference mix design table for the clay soil treated by the FGC stabilizing agent in accordance with the compressive strength of 50• 200kg/cm2 soilcrete with respect to the contents of soil stabilizer, fine sand, superplasticizer. And we could also find so much fibrous ettringite hydrates at the treated clay by FGC stabilizing agent through SEM photographs. In general fibrous ettringite hydrates are very effective for stabilization of the high water or organic soil. INTRODUCTION Soil-cement is a mixture of pulverized soil material and measured amounts of portland cement based soil stabilizer and water, compacted to high density. As the cement hydrates, the soil-cement mixture becomes a hard, durable paving material. Soil-cement is sometimes called cement-treated base or cement-stabilized-aggregate base. Regardless of what it is called, the principal governing its composition and construction are the same. Like in this study, engineering properties of FGC-treated base is similar to that of the ordinary lean concrete, so we will intend to call the FGC-soil mixture as soilcrete from now. In Korea with the stress of nature conservation, the application cases of soilcrete are rapidly increased at the light traffic road for park, farm, forest, golf course etc.. Because the leavings of weathered soilcrete are able to be returned to the surround nature without pollutions in short period.

ABSTRACT: This paper outlines the mitigation measures performed to address the liquefaction concerns of the foundation ground underneath a manufacturing plant site in Nagoya, Japan. Initially, a detailed soil investigation was performed and the liquefaction potential for the specified ground motion was evaluated. Considering the various site restrictions, compaction grouting was chosen as the most practical method to strengthen the foundation ground. Test acceptance criteria based on the relation between target N-values and fines content were established. In addition, dynamic soil-structure interaction analysis was performed to confirm the adequacy of soil improvement. This paper discusses the design and lessons learned from the grouting process and highlights the merits of compaction grouting as a practical method of ground improvement for seismic risk mitigation under existing structures. INTRODUCTION Buildings and other civil engineering structures constructed over loose saturated sandy deposits are highly susceptible to liquefaction-induced damage during major earthquakes. To mitigate such damage, remedial measures should be implemented around or under existing structures without adversely affecting them. In selecting the appropriate remedial measures for constrained and/or developed sites, various factors should be considered. These include effectiveness of improvement, required areas and depth of improvement, effects on surrounding environment, cost and ease of execution, and level of desired improvement, among others. In some instances, two or more remedial measures are combined t o produce the desired results. Because of its versatility and economy in improving ground beneath and around existing facilities, compaction grouting is gaining interest among engineers. Originating in the U.S., compaction grouting technology has been implemented in Japan only in the last ten years. Although initially developed for settle-ment control and re-leveling, the technology has been used to solve a number of geotechnical problems, among them the treatment of liquefiable soils.

ABSTRACT: Shear strength of clays will generally increase with consolidation under load. Large embankments on soft clays can be constructed by adopting a staged construction approach utilising the strength increase associated with consolidation. This paper presents a case history of a staged embankment construction carried out for the approach embankments of the My Thuan Bridge over the Mekong River, in Vietnam. The site of the My Thuan Bridge is underlain by soft clay deposits about 14 m to 18 m thick on the north and south sides of the river, respectively. Approach embankments about 7.4 m high with a 1.5 m surcharge were constructed at the site. The embankments were instrumented with inclinometers, piezometers, extensometers and survey monuments to assess the performance of the embankment during staged construction. Cone penetrometer tests and field vane shear tests were carried out after Stage 1 consolidation to assess the increase in shear strength and the stability under Stage 2 fill placement. T The increase in shear strength was also assessed in terms the measured settlement and applying soil mechanics theories. BACKGROUND The My Thuan Bridge site is located along the northern arm (Tien Giang branch) of the Mekong River, about 125 km south-west of Ho Chi Minh City. The bridge is a cable stayed bridge with a 350 m main span, 150 m side spans and 11 viaduct spans of 40 m on each side. The design road level at the middle of the main span is about 40 m above the high water level in the river. Approach embankments about 7.4 m high with a 1.5 m surcharge were constructed on each side. The bridge site is located on the Mekong River flood plains and comprises recent Quaternary age deposits to considerable depth.

ABSTRACT: Rapid urban development in the hilly terrain of Hong Kong involves the construction of high-rise buildings, many of which are supported on large diameter bored piles. These piles may sometimes have to be founded in slopes and have to resist severe wind loads during typhoon season. In order to minimise the transfer of lateral load from the buildings to the shallow depths of the slopes, an annulus of compressible material (referred to as sleeving) has sometimes been incorporated between the piles and the adjacent soils. In this paper, three-dimensional (3D) numerical analyses were carried out to examine the interactive effects of sleeved piles on slope stability. In the case of a single pile in a slope with a respectable safety margin, the sleeving technique is shown to be capable of minimising the adverse impact of lateral pile loading on local slope instability compared to an unsleeved pile, particularly under high lateral loading. In the case of a marginally stable slope which is vulnerable to external loading, whether the single pile is sleeved or not would make little difference to the global factor of safety. INTRODUCTION Rapid urban development in the hilly terrain of Hong Kong involves the construction of high-rise buildings, many of which are supported on large diameter bored piles. These tall buildings have to resist severe wind loads during the typhoon season each year. Local instability may be associated with the initiation of plastic deformation at the shallow ground in front of the laterally loaded pile, with development of successive cracks being likely to occur in sand (Uto et al., 1985), and large plastic deformation being likely to occur in clay. Global failure may occur if the soil mass supporting the pile develops a slip surface, accompanied by uncontrolled large displacements.

ABSTRACT: Geotextiles are currently specified in many different ways. Engineers specify geotextiles by brand name, mass, type, and/or any mix of properties including strength, puncture resistance, "G" Rating, EOS, and hydraulic properties. However, in Australia, no unified method exists of specifying geotextiles in a simple manner. Some specifications are unnecessarily biased against certain types of geotextiles, particularly wovens. Each State road authority has its' own method. This causes unnecessary confusion and complexity to engineers, manufacturers and contractors alike. This paper presents a case for adopting a simple, unified method of specifying geotextiles. Current Australian specifications are reviewed against worlds best practice. BACKGROUND Geotextiles have been used in Australia for over 30 years, beginning with the introduction of Terram, or "Terra-Firma" as it was widely known, imported by ICI many years ago. The key development in the local industry throughout the 1980"s was the setting up of a local Bidim non-woven manufacturing facility at Albury by Geofabrics Australasia in July 1987. Standards Developments In the late 1980's Standards Australia Committee CE/20 Geotextiles released the Draft Australian Standards for Geotextiles - series AS3706 which addressed general requirements, strength tests, hydraulic tests and durability tests. In 1990 Austroads published its' Guide to Geotextiles (Austroads 1990) which covered topics including Geotextiles Properties and Functions, Applications and Design, Durability, Construction and Testing. Due to lack of interest and funding there has been little further development work by Standards Australia or Austroads to standardize specifications for geotextiles. In Australia only the NSW RTA (Roads & Traffic Authority) has continued work in this area (RTA 1998 R63 Geotextiles, Separation and Filtration). In America AASHTO (the American Association of State Highway Transport Organisations) released its Standard Specification for Geotextiles M 288–96 (Ref.4) recently, which is widely recognised as worlds best practice.

ABSTRACT: In many countries in the world, especially Egypt, the possibility of damage to structures by soft ground constitutes a severe problem. Several methods are now available to overcome the problem of large settlement by improving the engineering properties of soft ground. One of the widely used techniques in improving the soft soil properties is preloading, in which the ground is loaded with uniformly distributed surface load prior to construction of the intended structure for a certain period of time. As large and powerful computing facilities become available, the need grows for numerical techniques that efficiently and accurately model the complex behavior of soft soil due to preloading. The target of the present paper is to present an appropriate numerical model that explains the preloading technique based on the results of an experimental study. A numerical procedure is proposed to predict the response of soft ground under preloading. Biot theory of consolidation with critical state soil model is used in solving the preloading problem. The model is then incorporated into a finite element program to solve the preloading problem. The applicability of the computational procedure is checked by comparing the numerical results with the experimental ones. The comparison indicates good agreement. INTRODUCTION In the last few decades there has been growing demand for construction of civil engineering projects on sites underlain by thick strata of soft cohesive soils. The geological and previous loading history of the site and details regarding subsoil types, stratification, strength, and compressibility characteristics are of relatively greater importance for successful use of preloading techniques than they are for other alternatives. The decision as to whether or not preloading is to be employed depends on a number of main factors. These factors are; compression characteristics of soil, pore water pressure, soil permeability, and secondary consolidation.

ABSTRACT: The reinforced soil retaining walls have become very common because of their versatility as compared to the conventional concrete retaining walls. Although these walls are in existence for about 40 years, their design is based on many conservative assumptions. In the absence of much prior experience, these empirical procedures were developed with sufficiently large factors of safety. A rational understanding of the behavior of these walls will lead to better designs and more reliability. In this regard, this paper first highlights the assumptions made in the current design procedures of reinforced soil retaining walls. A 6 m high retaining wall is designed using the current design procedures to determine the length and vertical spacing of reinforcement layers. The behavior of such wall is analyzed using the finite element method to assess the validity of the assumptions made in the design of these walls. The finite element analyses have been performed using a program developed by the authors. The elastic-plastic nature of the soil and the limited strength of the reinforcement materials are simulated during the analyses. The results from these analyses are discussed in the light of many assumptions made during the design of these walls. INTRODUCTION The reinforced soil retaining walls have been in existence for over 30 years. Their performance has been studied in detail by many researchers in the past to understand their behavior and develop appropriate design methods. These studies have included laboratory studies (Bathurst et al 1987, Wu et al 1992), field monitoring (Won et al 1994, Snowdon et al 1998) and finite element based simulations (Rajagopal and Bathurst 1992, 94 and 95, Ho and Rowe 1996 etc). For the design purposes, the reinforced soil retaining walls are into two parts i.e backfill and infill soils.

ABSTRACT: This paper discusses experiences in geotechnical investigation and design of several large container terminal facilities located throughout western Asia (including Sri Lanka, India and Turkey), in deep soft ground environments, with significant land reclamation components. Site investigation techniques and laboratory testing programs adopted are discussed generally, including comments on using often limited and basic services provided by local geotechnical contractors. The importance of providing experienced personnel on-site during site investigation work to ensure Òbest practicesÓ are followed is also discussed. The paper outlines geotechnical design recommendations made for three sites based on the results of site investigations. Recommendations relate to foundation (pile) design of wharf structures, land reclamation materials and techniques, settlement and stability of reclamation embankments and settlement monitoring equipment, pavement design and construction, and design for earthquake forces. INTRODUCTION In western Asia, industrial growth requires improved methods of cargo handling, which leads to expansions of existing port facilities and the construction of new ports. These port facilities need to be located along coastal zones with easy access to seas and oceans, and are nearly always located in areas underlain by deep soft marine deposits and include significant amounts of land reclamation. From a geotechnical design perspective, this results in challenging projects. Projects that Golder has been involved in over the past few years include expansions to the Colombo wharf, Sri Lanka; and the construction of new facilities at Mumbai, India and Derince, Turkey. These container terminals are being privatised by P&O Ports Pty Ltd in conjunction with various local and International partner companies. The structural design for the projects is being carried out by the Brisbane Office of Cullen Grummitt & Roe (International) Pty Ltd (CGR). Discussed below are some experiences gained through the geotechnical design of each of these port facilities.

ABSTRACT: In this study, we at tempted to develop methods of evaluating and predicting the risk of failure of rock beds and slopes facing roads in order to improve the efficiency of road disaster management under the limited funds and man power. INTRODUCTION Some areas of Japan face severe topographical and climatic conditions. Therefore, counter measures against natural disasters to ensure safe and reliable conditions throughout the country are indispensable for providing stability to people–s lives and ensuring the sustainable growth of the economy. Roads are a basic social infrastructure, however due to topographical reasons, are often constructed in close proximity to unstable rock beds and slopes that are vulnerable to collapses and failures. Road administrators have implemented disaster prevention measures against failures of rocks and slopes, but more than 100,000 sites still require such disaster prevention measures or management system based on daily inspection. There had been a resistance to active implementation of the concept of risk management in the field of disaster prevention managed by public sector. The reason for this was that administrators were apprehensive about being held responsible for any risk in the facilities controlled by the government, such as roads an driver levees, by disc losing the risk to the public. There is a possibility that the occurrence of negative events is has tally connected to administration errors, as is pointed out by Okada and Kobayashi (1993). However, in order to undertake more effective and efficient road disaster management under the limited funds and manpower, it is necessary to develop the risk evaluation and management technologies that can clarify the effects of disaster prevention investment and improve public accountability. This study therefore attempts to develop methods of evaluating and quantifying the risk of failure of rock beds and slopes in road disaster management.

ABSTRACT: This paper investigates the mechanism of slope displacement using the results of long-term monitoring of the unstable behavior and failure of a large excavated rock slope with an elevation difference about 300 m. The study also evaluates the influence of joint sets on slope behavior through numerical analysis. Then fundamental points regarding the stability of large excavated rock slopes are introduced as follows. The stability of a large excavated rock slope is greatly influenced by the joints and weak layers in the rock, and the relationship between their positions and the positions of the excavated surface. It is important not to fail to notice signs of instability caused by the influences of them early through long-term monitoring started in the early stages of excavation. Based on such monitoring, the need of actions should be determined such as additional investigations, stability analysis, and design modifications and changes. INTRODUCTION This paper focuses on a case of failure of a large excavated rock slope with a height (an elevation difference) about 300 m. First, the behavior of each part of the slope is analyzed based on the displacement measurements obtained during a period of about 10 years before the failure. Next, each cross section of the slope is modeled by elasto-plastic equivalent continuum analysis to illustrate that the measurements are explainable. And how the unstable behavior of the slope occurred according to the topographical and geological conditions of the respective cross sections is examined. SLOPE DEFORMATION BEHAVIOR BASED ON LONG-TERM MEASUREMENT Geological structure The slope involved in this case study consists of late Paleozoic to early Mesozoic olistostrome: limestone, shale, tuff, and sandstone. The alterations of shale and tuff include lenses of sandstone, and these layers are overlain by olistoliths of limestone.

ABSTRACT: The paper summarizes work by the writers that is focussed on a program of full scale model tests of geosynthetic reinforced soil walls carried out by the Geotechnical Research Group at the Royal Military College of Canada (RMCC). Over a period of 13 years, a total of 13 significant full scale walls have been constructed. All of the structures were surcharge loaded to stress levels well in excess of working load conditions and in several cases were taken to collapse. The data gathered from this program has been useful to identify important performance features of the reinforced soil structures and to identify sources of conservatism in current methods of analysis for geosynthetic reinforced soil wall structures in North America. The high quality data has also proved useful for calibration of numerical models. INTRODUCTION The Geotechnical Research Group of the Civil Engineering Department at the Royal Military College of Canada (RMCC) is engaged in a long-term research project related to design and performance evaluation of geosynthetic reinforced soil structures. A major component of this research has been the construction, surcharge loading and monitoring of instrumented full scale geosynthetic reinforced soil retaining walls. In total, 16 full scale test structures have been built over a period of 13 years of which 13 have been significant wall models. RMCC RETAINING WALL TEST FACILITY Test models have been constructed in the RMCC Retaining Wall Test Facility located within the Civil Engineering Department structures laboratory at RMCC (Figure 1). The test facility in its current configuration allows walls to be constructed that are 3.6 m high by 3.4 m wide and extending up to 6 m from the front edge of the facility. Some early models were constructed when the inside dimension of the facility was 2.4 m wide.

ABSTRACT: The aim of this paper is to present the main design and construction criteria considered on some vertical jet-grouting solutions adopted by Tecnasol FGE. On these solutions ground improvement by vertical columns was successfully used as an alternative to traditional solutions, such as concrete cast in-situ pile foundations, earth retaining sheet pile walls and micro-piles for underpinning. On each case history, the following topics are presented: main scenario, geotechnical conditions, initial solution, main design criteria and construction issues. INTRODUCTION Jet grouting methods have initially been developed in Japan, the UK and Italy. For about 20 years it has been applied world-wide. In Portugal the technology has been adopted in the last 5 years, mainly on Lisbon underground extension works. Recently, vertical jet grouting solutions have also become competitive and advisable in several and more usual geotechnical scenarios. CASE HISTORY 1 - SANTA LUZIA BRIDGE DEEP FOUNDATIONS Main design and construction criteria Main scenario: Santa Luzia is a 17+27×3+17m twin span concrete bridge on Madeira island, founded on an alluvium zone, filled with boulders. Each one of the 2×2 central piers carries an axial, permanent and live, service load of about 15000kN. Geotechnical conditions: the bridge is founded on an heterogeneous alluvium, filled with weathered basalt boulders. At the surface the alluvium is softer and involved on a sandy matrix, becoming with deep consolidated and involved on a clay matrix. The basalt bed rock is located at a variable deep ranging from 12 to 24m. Initial solution: traditional f1000mm cast in-situ concrete piles foundation, resting on the basalt bed rock. This solution was changed due to technical difficult on drilling basalt boulders. Main design criteria: a vertical jet grouting solution was designed in order to improve the alluvium behaviour.

ABSTRACT: A novel plane strain approach is introduced to model the behaviour of embankment foundations on soft clay stabilised with vertical drains, where the classical axisymmetric solutions are converted to an equivalent plane strain model, incorporating the effects of smear and well resistance. This paper describes the behaviour of an embankment stabilised with vertical drains, where a specific case history is selected from Malaysia. The consolidation of soft clay is modelled on the basis of the modified Cam-clay. The settlement behaviour at various stages of embankment loading is analysed using the finite element technique, and the numerical results are compared with field measurements. The behaviour of drains with and without smear is also compared. Inclusion of smear effect in the mathematical model improves the prediction of settlements. INTRODUCTION The deformations of soft clay foundations stabilised with vertical band drains has remained difficult to predict accurately, although a significant progress has been made in the past few years through rigorous numerical modeling. Attributed to the rapid development in computer technology and the increasing versatility of the finite element method, a thorough numerical analysis of the settlement of the soft soil stabilised with multiple vertical drains can now be conducted. Following previous developments (e.g. Cheung et al., 1991; Hird et al., 1992), Indraratna and Redana (1997) extended the analysis based on the plane strain solution to include explicitly the effects of smear and well resistance. Although a single-drain analysis is often performed to model the soil behaviour along the embankment centerline (symmetric geometry), multi-drain analysis is essential to study the overall behaviour of a soft clay foundation underneath the embankment. This paper presents a plane strain, multi-drain analysis for a selected case history from Malaysia, along the North-South Expressway built on the Muar coastal plain.

ABSTRACT: The geomechanical models for slope design, which was mainly based on shear strength parameters estimated by using RMR classification system, are compared with the real post Ð construction conditions of cuts. The results of this study show that RMR classification system generally leads in a rock mass quality underestimation, which mainly due to the rating adjustment for discontinuity orientations as especially proposed for rock slopes. The case records evaluation indicate that the rock mass rating without taking into account the discontinuities adjustment give a more realistic rate of rock mass shear strength characteristics for preliminary slope stability analysis. Also, the shear strength parameters, as determined by the use of GSI, seems to lead in an overestimation of slope stability of these limestone cuts. INTRODUCTION The determination of representative shear strength parameters of a rock mass is often a time consuming, costly and difficult process. Large-scale in situ shear tests are desirable but very expensive. It is known that there are the following lines of approach that can be used to obtain information on in situ behaviour of the rock mass for slope design: direct measurements by means of field and laboratory tests, evaluation by means of mathematical simulations, evaluation of stable and unstable natural and excavated slopes and, empirical methods using rock mass classification systems. The last approach is often applied in many cases for the preliminary design of high rock slopes in Greece and mainly for heavily jointed rock masses assuming isotropic rock mass behaviour. The Geomechanics Classification Rating (RMR) system developed by Beniawski (1976, 1979, 1989) is the common way to obtain the range of shear strength parameters and then to estimate the safety factors by using slope design charts for circular failure surface or other calculation methods (Hoek and Bray, 1974).

ABSTRACT: In this paper, a new approach using genetic-based evolution algorithm without gradient requirement is proposed for the optimum design of piled raft foundations. An objective function considered is differential settlements based on a serviceability of structures and total weights of raft and piles based on a cost of structures. Genetic-based evolution algorithm is a search or an optimization technique based on nature selection. Successive generation evolves more fit individuals on the basis of the Darwinian survival of the fittest. In the process of formulating genetic algorithm (GA) - based optimum design procedure, the analysis of piled raft foundations is performed based on the "hybrid" approach developed by Clancy (1993), and also simple genetic algorithm by Goldberg (1989) is used. To verify the efficiency of the proposed GA-based optimum design procedure, two design examples of the piled raft foundations (5 × 5 and 3 × 3 group piles) are analyzed. In addition using the proposed optimum design procedure, parametric studies are performed with an aim of examining the effects of relevant variables on the optimum design of piled raft foundations. INTRODUCTION Civil engineers frequently work with optimization problems, such as structural design, resource allocation, transportation routing, and so forth. Traditionally, most optimization problems have been solved using operations research (OR) techniques, such as mathematical programming that a lot of gradient information is required. While the traditional OR approach requires different algorithms in solving different mathematical programming problems, genetic algorithm (GA) - based method can be solved to different optimization problems using the same genetic algorithm. Only the fitness and constraint functions are modified for different mathematical programming problems. In this paper, a new approach using genetic-based evolution algorithm without gradient requirement is proposed for the optimum design of piled raft foundations.

ABSTRACT: This paper focuses on the selection of soil slope stabilisation techniques. It considers the factors which influence the choice of technique through the development and use of a webbased decision support system and the examination of a landslide in Edinburgh, Scotland. The paper highlights the potential benefits of the integrated use of bio-engineering techniques and conventional stabilising methods INTRODUCTION The number of alternatives for soil slope stabilisation is large; ranging from simple drainage measures, through the use of bio-engineering techniques to the more traditional use of gravity and embedded retaining structures. The analysis of these alternative remedial measures for soil slope problems requires experience and sound judgement on the part of the engineer. In evaluating the alternatives, the engineer will be influenced by factors such as: nature of failure; ground & groundwater conditions; ground topography; environmental impact; availability of materials, labour and equipment; design life and maintenance requirements; adjacent and underground structures; confidence in design and construction; time constraints; and costs. The final decision will not normally be straightforward as it will be based on a number of these and other inter-related factors and will often have considerable cost implications and degree of success in terms of obtaining a practical and meaningful result. The purpose of this paper is to outline the selection of soil slope stabilisation methods and to discuss the recent developments of a web-based decision support system. Also presented is the integrated use of geotechnical and bio-engineering techniques which allow cost-effective and environmentally acceptable solutions without recourse to large and expensive geotechnical measures alone. Finally, an examination is carried out on a number of different methods for stabilising a landslide in Edinburgh, Scotland. Here, four proposals are described and examined to highlight the factors which influenced the choice of the adopted approach.

ABSTRACT: A "step-path" method for determining the statistical shear strength along critical failure paths through jointed rock slopes is reviewed. The computed shear strength is a function of both sliding and "stepping-up" along sets of suitably orientated geological discontinuities within slopes and of shearing through either the intact rock or rock mass substance where such critically orientated discontinuities are absent. Details of STEPSIM4 (Monte-Carlo based software developed for this analysis), input rock mechanics parameters, ensuing strength outputs and several illustrative examples are presented. STEPSIM4 facilitates a more realistic assessment of slope stability risks. It is a software tool that provides an avenue for combining hard factual data with data that may be only approximate or judgmental. Some inputs may be the user''s best estimates, provided that the outputs are then viewed accordingly. STEPSIM4 complements the existing geotechnical approaches. It does not replace commonsense, site-specific experience and good engineering judgment. INTRODUCTION Background Rock masses are systems comprising intact rock and geological discontinuities. As conceptually shown in Figure 1, high rock slope failures may involve several mechanisms. Many landslides exhibit composite failure modes. Sliding may occur along large numbers of "relatively" short, adversely dipping, geological discontinuities within the rock mass. This process is often accompanied by dilation of the mass as the failure path "steps up" on other subvertical discontinuity sets within the mass and by shearing through and/or tensile failure of the intact rock and/or rock mass "bridges" between the discontinuities. Geotechnical assessment of the mean and the likely statistical variability in the shear strength parameters for composite failure paths such as the conceptual one shown in Figure 1 is not always a straightforward task. The STEPSIM4 "step-path" method provides an avenue for assessing the statistical shear strength along potential two-dimensional failure paths through rock masses.

ABSTRACT: In this paper a numerical analysis of slope stability problems in blocky rock is presented with emphasis given to the various possible failure modes (block sliding and/or block tilting). The discontinuous structure of the rock mass is approximated by an equivalent Cosserat continuum. This implies the introduction of couple stresses and internal rotations which model the relative rotations between blocks and the bending stiffness of the blocks. The model is implemented into a large strain finite element program. INTRODUCTION It is quite common to observe a rock mass which was broken by tectonic stress in such a way that from the macroscopic point of view it gives the impression of a regular bock structure. The response of such structured systems can be dealt with either by using a discrete (explicit) approach if the rock mass contain a relatively small number of major discontinuities or by using an homogenised model if on the contrary the characteristic size of the individual blocks is very small as compared to the characteristic size of the problem (height of a slope, diameter of an excavation). For intermediate situations, in order to overcome the limitations of classical homogenisation and to expand the domain of validity of the continuum approach one has to consider the salient features of the discontinuum within the frame of generalised continuum theories (Vardoulakis and Sulem 1995). Consequently the framework of a Cosserat continuum theory is used here to model the behaviour of blocky rock (Mühlhaus 1993). In Cosserat''s theory a material point of the continuum has three additional rotational degrees of freedom as well as the three translations of a classical continuum. In a regular block structure, one can consider the influence of relative rotations between blocks by means of additional Cosserat rotations.

ABSTRACT: This paper presents the measured behavior of an anchored segmental retaining wall. A segmental retaining wall reinforced with steel bar-anchor block systems has been recently developed and implemented in Korea. In an attempt to understand the overall mechanical behavior of the anchored segmental retaining wall and to confirm the applicability of the current design approaches, an extensive monitoring program has been implemented to a 7.0 m high anchored segmental retaining wall. The measured results are then carefully analyzed to identify fundamental features of the behavior of the wall, including lateral wall displacement, earth pressure distributions acting on the wall facing units as well as anchor blocks, strains in steel bars, and lateral movement of reinforced zone. Based on the results, the validity of the current design method is evaluated. The implications and findings from this study are discussed. INTRODUCTION Soil-reinforced segmental retaining wall(SRW) systems have become popular in Korea since their first appearance in the early 1990's for reasons of performance, aesthetics, cost and expediency of construction. Especially at sites with poor foundation conditions, the SRW systems offer significant technical and cost advantages over conventional concrete retaining walls. Most of the SRW systems introduced in Korea have adopted extensible reinforcements such as polymeric geogrids. Recently, steel bar-anchor block systems have been put into practical use instead of geogrids, as illustrated in Figure 1, showing a schematic view of segmental block-steel bar system. The steel bar-anchor block system offers several advantages over polymeric extensible reinforcements, such as greater reinforcing effect due to its high stiffness, less susceptibility of installation damage and less or no time dependent deformation. Anchored earth systems have developed from a combination of the techniques used in reinforced soil as well as soil anchoring, and are being widely used in various countries.