ABSTRACT: The Morell Bridge, the first arch bridge constructed in Australia using the Monier system of construction, was completed in 1899 in Melbourne and had an estimated life of 50 years. It is of historic significance not only for the first use of the construction technique but because it was built in the dry then a new man made channel was cut under it to eliminate a sharp S bend in the Yarra River. The south abutment of the bridge is founded in weak siltstone, while the north is founded in soft alluvial deposits. The bridge consists of 3 arches. The northern most arch has exhibited some distress and movement over the life time of the structure. Originally called Anderson Street Bridge, the bridge was renamed in 1935. Construction of the Melbourne CityLink project required a major excavation close to the northern abutment where the 1.6 km Domain tunnel reaches ground level and the new Punt Road interchange is constructed. Morell Bridge became one of the most monitored structures in Melbourne during the construction of the City Link Project. Initial review and analysis placed the bridge at significant risk from lateral movements during construction. The risk was highlighted by the previous problems associated with the northern arch. A temporary works solution together with monitoring was instigated to minimise and identify movements and provide stakeholder comfort. Monitoring, primarily focused on the northern abutment, has included inclinometer readings, regular precise horizontal and vertical level surveys and crack monitoring. Detailed analysis of the bridge and its structure were carried out at various stages during the currency of the project. Movements, not surprisingly, were detected throughout the works. BACKGROUND The Morell Bridge over the Yarra River lies just to the south of the entrance portal area to the new Domain Tunnel.

ABSTRACT: A large coal stockpiling and transhipment development at Paradip, on the Bay of Bengal, involved raising of a soft soil site using hydraulically placed dredged fill. This case history describes the investigation, design, construction, and settlement performance the stockpiling area. Limited geotechnical data lead to pragmatic design with implications for reliability of settlement performance. Investigation and design included two trial embankments, drillholes, static cone penetration profiling, and laboratory tests. Design formulae for settlement magnitude and time were developed using theoretical and empirical relationships. Settlement plates and pneumatic piezometers were used to calibrate and update the design relationships during construction. Design of the fill placement scheme was based on geotechnical constraints, particularly consolidation time. Despite losing most instrumentation by the completion of preloading, performance data was sufficient to achieve preloading with an acceptable level of reliability. Application of the observational method at a difficult site in a remote location has demonstrated that reliable outcomes can be achieved provided they are based on an established conceptual framework. INTRODUCTION AND SETTING Paradip is a dredged deepwater harbour located on the Bay of Bengal approximately 400Êkm southwest of Calcutta, India (FigureÊ1). A 20ÊMt/a coal transhipment facility is being developed to service the domestic power coal market. The site lies within a large delta adjacent to the main distributary channel of the Mahanadi River. The geology of the coastline area includes dune sands, a basal marine transgressive silty sand and Recent estuarine and alluvial sedimentation. The wave-dominated delta includes abandoned channels filled with fine sands, silts, and clays. Under the site at about 15Êm depth is the Pleistocene disconformity, an oxidised and fissured stiff sandy clay and dense sand, which is underlain by a thick sequence of older deltaic and marine transgressive sediments. FigureÊ1 also shows a general view of the project site.

ABSTRACT: The main objectives of developing soil models and numerical methods are to provide tools for predicting the field behaviour. This can only be justified against carefully selected case histories. This paper presents a study on porewater pressure and deformation responses in clays at the sites of two case projects, that is, an artificial Tarsiut Island on marine clay in the Beaufort Sea and Berthierville test embankment on soft ground in Quebec, all in Canada. INTRODUCTION It has been reported that the excess porewater pressure in clay underneath Tarsiut caisson retained island increased for many months following completion of construction (with vertical load unchanged). Nobody has ever simulated successfully this phenomenon of excess porewater pressure increase under constant loading at the Tarsiut island site before. A newly developed three-dimensional (3-D) elastic viscoplastic (EVP) model (Yin and Graham 1999) is implemented in a finite element (FE) program to analyse the consolidation behaviour of the clays under Tarsiut island loading. The phenomenon of porewater pressure increase with time following the completion of the island construction has been successfully simulated. The mechanism of the porewater pressure increase due to creep is explained also in this paper. Finite element consolidation modelling of the soils underneath Berthierville test embankment is then carried out. It is found that the compression of the clay layer computed from the FE model is in good agreement with field measured values. Pore water pressures from the FE modelling are close to the measured values except for the value sat the initial loading stage. CONSOLIDATION MODELLING OF CLAYS UNDERNEATH TARSIUT ISLAND The Tarsiut island was a man-built artificial island, located approximately 60 kilometres offshore with sea water depth approximately 21m. This artificial island consisted of four independent concrete box caissons set on an underwater sand berm.

ABSTRACT: From the early days of simple slurry injection to current sophisticated techniques, grouting has played, and continues to play, an important role in remediation and new construction worldwide. As new grouting technology is developed, and existing technologies are refined, the range of applications increases. This paper presents four grouting techniques – compaction, permeation, jet and soil fracture – that have particular relevance in today's global construction marketplace. A brief introduction to each technique is followed by discussion of recent advances, illustrated by case studies of applications. COMPACTION GROUTING Compaction grouting is the strategic injection of a low-slump mortar grout under relatively high pressure to displace and compact soil in place. This technique was pioneered on the west coast of the United States in the 1950s, and is the only grouting technique to have its roots in that country. Developed to overcome the lack of control of travel and set times associated with conventional slurry grouting, compaction grouting was first used to rectify settled structures. However, in recent years its use has also been centered on new and different applications in soils previously believed to be untreatable by this method. Site Improvement For Liquefaction Mitigation Perhaps the most significant advance in the use of compaction grouting has taken place in seismic regions. Open Sites Typically, on large, relatively open sites, vibro stone column construction or dynamic compaction is used to achieve the majority of the required improvement. However, such sites may also abut, or include, surface or underground structures sensitive to the vibrations induced by these methods. Alternatively, overhead obstructions may preclude the use of large equipment. In these circumstances, compaction grouting, with its small, maneuverable and vibration-free equipment, is effective in achieving the improvement needed without adversely affecting surrounding features.

ABSTRACT: This paper reports a case study of site investigation and remediation of a soil contaminated with Trichloroethylene (TCE) at a factory site still in operation. Early investigation indicated contamination of the ground surrounding a warehouse building. This soil was excavated and treated on-site by soil vapor extraction. Meanwhile, the degree of contamination of the soil under the warehouse building was determined by several borings in horizontal direction from outside the building. The locations of the borings were designed such as to serve later as wells for the vacuum extraction. GEOLOGICAL FEATURES OF INVESTIGATION AREA The factory site is located on a terrace that is part of a fan deposit derived from colluvial volcanic deposits and debris flow. The surface has a gradient of 4/100 (Figure 1). The geology of the terrace is dominated by gravel, sand, mud and volcanic breccia (andesite). The surface stratum is loam of aeolian deposits, with a thickness of about 10 m. The factory was built on leveled ground, which had been achieved by excavating soil uphill and backfilling downhill. Groundwater level is from 12 m to 14 m below ground, and its flow direction is roughly identical to the gradient of the natural ground surface. Also flow direction of water in surface layer and groundwater are alike. INVESTIGATION OF CONTAMINATED SOILS WITH TCE The factory had been using Trichloroethylene (TCE) as a solvent for cleaning of electronic devices. But that practice was abandoned at several years ago to follow legal restrictions. The investigation pursued two goals. One was to confirm whether or not the ground underneath pipe fittings of the storage tanks had been contaminated with TCE. A second goal consisted of carrying out a general investigation for the whole factory ground according to a national guideline.

SUMMARY: The excavation of a road tunnel in a region with complex hydrogeological conditions and the presence of valuable mineral water springs is the subject of this case history paper. The tunnel comprises two sections, Frasnadello and Antea, linked by a bridge, and has a length of 2400 m. Located in the Brembana valley, near the town of San Pellegrino Terme, to the North of the city of Bergamo (Italy), the tunnel was excavated in 1996–97 through Dolomite, Limestone and Argillite Formations, by a large diameter (11.8 m) Tunnel Boring Machine (TBM). The excavation took place as the final enlargement of an exploratory pilot tunnel (3.9Êm in diameter), which was excavated again by a TBM, more than two years in advance of full size excavation. The content of the paper is considered to be well in line with the main theme of the GeoEng 2000 Conference as geo-engineering concepts and methods are applied to engineering practice, through the use of a large spectrum of the geo-engineering disciplines. The first part of the paper describes the series of investigations (including geological, geomorphological and geostructural studies, borehole logging, and geophysical surveying) undertaken in order to tie-down the geology and to increase the understanding of the hydrogeology in the area of the mineral water springs, also to derive a predictive picture of the rock mass conditions along the tunnel alignment. In addition, a numerical modelling study was performed in order to evaluate the influence of tunnel excavation on the springs discharge. Then, the attention is moved to the full-size excavation of the main tunnel. A description is given of the stress analyses carried out in order to assess the stability conditions and to evaluate the stress distribution in the primary lining, in terms of rock-structure interaction considerations.

ABSTRACT: The outward movement of a stepped brick retaining wall followed the near completion of a reinforced soil embankment in Paisley, Scotland. The wall was located at the toe of the embankment and the movement was sufficient to lead to serviceability failure of the wall. This paper reports on the investigation into the serviceability failure of this wall and its interaction with the reinforced embankment. The paper also offers general advice on the design and construction of interactive structures. INTRODUCTION As part of a new housing development in Paisley, Scotland a 6m high reinforced embankment approximately 70m long was constructed using indigenous clay fill. Prior t o this construction a 2.5m high stepped brick retaining wall was built which formed the toe of the embankment for a length of about 40m (Figure 1). On near completion of the embankment, the top of the retaining wall moved outwards a maximum horizontal distance of approximately 12cm. This movement resulted in the wall having a front face batter of 1 in 12. The purpose of this paper is to report on the investigation of this failure and to offer some general advice on the design and construction of interactive structures. The main aims of the investigation were to ascertain the reasons for failure of the wall, to establish whether or not the reinforced embankment had also failed and to determine whether any aspects of the construction of the embankment had contributed to the wall failing. INVESTIGATION Field Tests & Observations As part of the investigation a set of density field tests were conducted and bulk samples of the embankment material were obtained. All tests and samples were taken at the levels shown in Figure 2 (B1ÉB5) and span the most critical section of wall and embankment.

ABSTRACT: Two case studies of embankment failure at a reclaimed site in Singapore were carried out. Both the limit equilibrium slip surface method and the finite element method were employed in the studies. The analysis indicated that the critical fill height predicted by the limit equilibrium method was affected by the shear strength of the embankment fill, whereas that assessed from the finite element analysis was controlled by the input parameters of the foundation soil. Both the limit equilibrium method and the finite element method give reasonable prediction of the critical fill height when proper soil parameters and slope are chosen. The finite element analysis provides a better prediction of the actual slip surface than the limit equilibrium analysis. INTRODUCTION Limited land space in many countries in the East and Southeast Asian region has led to extensive foreshore land reclamation for diverse uses. In the planning and design of land reclamation, the stability of the fill resting on foundation soils is important. However, the analysis method provides no information on the change of stress and strain in the soil. For a detail understanding of the problem, the finite element method (FEM) may be useful. This paper describes two case studies involving embankment failure at a land reclamation site at Changi East in Singapore, one involving the placement of hydraulic sandfill and surcharge over a slurry-like soil mass in a silt pond and the other over a natural soft marine clay beneath the seabed. Both SSM and FEM are used in the analysis. A limit equilibrium based computer program PCSTABL developed at Purdue University is employed for the slip surface analysis. SAGE CRISP, a critical state finite element program developed by Sage Engineering and Cambridge University, is adopted for stress and deformation analyses.

ABSTRACT: In industrialized countries one of the legacies of the past is contaminated ground due to mining, industry and society disposing of waste with little regard for future consequences. Frequently contaminated ground is associated with abandoned sites which occur within urban areas and as such are not compatible with the concept of sustainable development which calls for the re-use of such sites. The key to effective re-use of such land is harmonized management of ground investigation, risk assessment and clean-up strategies. One of the case histories considered involves a site investigation for a relief sewer in Glasgow, Scotland. As the site investigation progressed it ran into made-ground which contained waste from an old chemical works. The second case history involves the site of an abandoned coal mine in the Ruhr district of Germany, which had been operative for almost 90 years. INTRODUCTION One of the legacies of the past in industrialized countries is that land has been contaminated. Contaminated land has come about because industry and society tended to dispose of their waste with little regard for future consequences. It is land which contains substances which can cause harm to living organisms, pollute water or interfere with the ecosystem. It can take many forms, and can be variable in nature across a site and each site has its own characteristics. The key to effective rehabilitation of contaminated land involves the harmonized management of ground investigation, risk assessment and clean-up strategies. However, the accumulation of large amounts of data from various sources for a major site can represent a problem of processing. Digitization of data for the production of various site plans can be accomplished by a regular CAD application or a geographical information system (GIS). In addition, data can be represented in three-dimensions with the aid of a suitable work-station.

ABSTRACT: Different types of waste waters and effluents may be produced as a result of mining. Generally, the major pollutants are suspended solids, dissolved salts or acidity. In the latter case, acid mine drainage refers to the oxidation of sulphide minerals, notably pyrite, which are exposed in a mine or are present in spoil. The primary oxidation products of pyrite are ferric and ferrous sulphates, and sulphuric acid. Two case histories are provided which deal with the problem of acid mine drainage associated with mines in South Africa. The first refers to a tin mine in the North West Province where acidic waters were produced by heaps of pyrite discard. The second refers to a mine in the Witbank Coalfield where acid groundwater emerges from the mine as springs and to has led to the decimation of vegetation, and to the eradication of aquatic flora and fauna in a nearby stream. INTRODUCTION The term acid mine drainage is used to describe natural oxidation of sulphide minerals which occur in mine rock or waste which are exposed to air and water. This is a consequence of the oxidation of sulphur in the minerals to a higher oxidation state. If acid mine drainage is not controlled it can pose a serious threat to the aquatic environment since acid generation can lead to elevated levels of heavy metals and sulphate in the water which obviously has a detrimental effect on its quality. Certain conditions including the right combination of mineralogy, water and oxygen are necessary for the development of acid mine drainage. Such conditions do not always exist. The ability of a particular mine rock or waste to generate net acidity depends on the relative content of acid generating minerals and acid consuming or neutralizing minerals.

ABSTRACT: This paper presents the results of a study on evaluation of liquefaction potential of ground along the alignment of power channel of a hydroelectric power project in the Uttar Pradesh State of India. Results of field Standard Penetration Test (SPT) and laboratory Cyclic Simple Shear Tests were used in the analysis for determining cyclic strength of the soil. SeedÕs Simplified Procedure was employed for evaluation of liquefaction potential. Based on the analysis carried out for different magnitudes of earthquake, it was concluded that the top soil is susceptible to liquefaction due to an earthquake of magnitude of 4.5 or more on Richter scale occurring at a distance of 25 km. INTRODUCTION Tanakpur Hydroelectric Project is a run-of-the-river scheme across river Sarda and is located upstream of Banbassa barrage in Uttar Pradesh State of India. The 475m long barrage is located at Tanakpur. A 6387m long power channel takes off on the right bank of Sarda River. Soil investigations carried out for the power channel indicated Standard Penetration Test (SPT) values in the range of 3 to 5 up to a depth of about 3m in a predominantly fine silty sand. This type of soil was suspected to liquefy under earthquakes. A study was, therefore, undertaken to evaluate liquefaction potential of the soil to ascertain the threshold level of earthquake that could trigger liquefaction. FIELD INVESTIGATION DATA Field test data supplied by the project was in the form of SPT values obtained by conducting standard penetration tests at six locations on the natural ground along the alignment of power channel. The tests were carried out to different depths at each location. The maximum depth of investigations was 3.7m. The topsoil was found to be weak and the thickness of weak soil varied between 2.2m to 3.7m.

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: 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: 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: This paper presents the analytical displacement of the sheet pile braced excavation system by means of the FEM technique based on case studies of deep excavation in Bangkok city with full geotechnical instrumentation. The research sites consists of 4 projects where the field measurement was recorded corresponds to the construction techniques and sequences. These four case studies had different boundary conditions with the excavation depth varied between 8–11 m. while the bracing spans and construction techniques were different. The back-figured values for soil stiffness in terms of Young's modulus are calculated as Eu/Su = 150, 250 and 1000 for soft Bangkok clay, medium clay and stiff silty clay, respectively. The results have later been confirmed with the first self-boring pressuremeter tests in Bangkok subsoils. INTRODUCTION Deep excavations in Bangkok City of Thailand are still necessary even though the country has faced an economic crisis. There are still required the necessary civil works to serve the demands and to solve the environmental problems such as our first underground MRT subway project as well as the waste water treatment schemes. Bangkok subsoil conditions consist of a very soft dark gray clay about 12–14 m. thick, underlain by stiff clay to about 23–25 m. depth then followed by the first dense silty sand layer. Excavation in such soft dark gray clay requires efficient retaining structures such as reinforce concrete diaphragm walls for deep excavation and temporary sheet piles for shallower excavations. The sheet pile work is generally applied for excavations up to about 10–11 m. depth. Use of sheet pile systems is very popular because the construction cost is cheaper, the piles are reusable and simple for the contractor. Lateral wall movement that will not induce any damage to the adjacent areas normally controls the depth of excavations.

ABSTRACT: Dewatering of soils by wells and wellpoints is a cost effective way of controlling pore water pressures and inflows into deep excavations. Traditionally installations have been carried out by drilling from the surface and installing wells with sand filters placed around a wellscreen by gravity. This has restricted their use to essentially vertical wells. The methods of overcoming the filter placement problem means that cost effective dewatering solutions can be applied in certain situations which would traditionally have been overcome by the more expensive and time consuming techniques of grouting, compressed air or freezing. The paper addresses the methods that have been developed and the practical constraints encountered by means of a series of case histories. INTRODUCTION The author became interested in alternative ways of improving drainage over twenty years ago whilst studying the oil industry technique of introducing "proppants" into hydraulically fractured wells to provide higher permeability drainage paths. Early experiments in using such techniques in soft soils by injecting sand suspended in a polymer to accelerate consolidation led to an understanding of the problems and in 1991 an opportunity arose to demonstrate that this work could be utilized in a dewatering project where conventional techniques did not apply, i.e. from a tunnel under the sea. Horizontal drains have long been used in rock and competent soils, the Qanats or Karezes of the Middle East probably represent the oldest form of horizontal drainage. In Hong Kong the techniques have been developed for draining rock slopes to improve slope stability and many of the drilling and maintenance problems addressed (Martin et al, 1994). Horizontal controlled drilling techniques have been used in recent years to install relatively simple drains in landfill sites where presumably a slotted pipe is installed within a casing string and the casing removed.

ABSTRACT: The highwall mining method was introduced in Australia in early 1991. Since then, at least 13 mines have used this method to mine coal. Abundant experience has been accumulated during the past 8 years, through some failures as well as successes. This paper presents a brief review of highwall mining experience at four Australian mines, with focus on geotechnical issues affecting mining performance. The paper also summarizes one case study, which involved major pillar/roof instabilities. The aim of the review and the case study is to assist the highwall mining industry to learn from past experience and to avoid similar instabilities in the future. INTRODUCTION Highwall mining is a remotely controlled mining method which extracts coal from the base of an exposed highwall, typically via a series of parallel entries driven to a significant depth within the seam horizon. The method allows recovery of coal from surface pits that have reached final highwall position due to uneconomic stripping ratios, or in areas where coal has become sterilized in, for example, service corridors. The current highwall mining technologies originated in the USA in the mid-1970's. Two types of highwall mining systems have been commonly used: the Auger System which creates separate or twin circular holes of various diameters, and the Continuous Highwall Mining System (CHM) which mines rectangular entries, usually 3.5m wide. These technologies were first utilized in Australia in early 1991 when Callide Mine used an Auger System to mine coal. Since then, at least 13 coal mines in Australia have applied the highwall mining technologies over more than 30 pits. The CHM has been more widely used than Augers because of its advantage in productivity and recovery rate. A typical CHM operation is illustrated in Figure 1.

ABSTRACT: Due to the increase in service loads of foundations, a worldwide trend is being followed by geotechnical engineers and designers to measure the real behaviour of the pile-soil interaction. Historically, this was defined by the Load-Displacement Curve, obtained from a Static Load Test, and the concept of bearing capacity…if those involved in the project arrived to an agreement on its definition. Technology developed and the concept of Dynamic Load Test (DLT) arrived, bringing with it an economic and faster way of measuring the response of piles to imposed loads. But is this what the geotechnical engineer requires? A comparison between DLT and SLT is analysed throughout the eyes of a geotechnical engineer and not from the perspective of a testing house. Different types of piles were tested with both methods, seeking for correlation, side effects and installation influence in results, aiming to know the real performance vs. predictions. INTRODUCTION In the first half of the '80s, it was introduced in Argentina the pile testing speciality based on the Stress Wave Theory; at the beginning through the Sonic Integrity Test (SIT), as a parameter for control quality of foundations and, afterwards, with the Dynamic Load Test (DLT) in order to measure the pile-soil behaviour. But up to then, how was determined the bearing capacity of a piled foundation? During those years, where Quality Assurance (QA) started to play an important role in the Argentinean construction market, as well as the increment in service loads, lead to an increase in the demand for verifying piling works. As well, a reactivation of the local economy, the availability of new technology in construction methods and tighter schedules for finishing site works, allowed the DLT to be introduced as an alternative to the cumbersome static test.

ABSTRACT: There are relatively few reported field studies on the behaviour of laterally loaded rock socketed piles. This paper presents case studies of piles socketed in granite and sedimentary rocks that have been laterally load tested to failure. The load-deflection response, and deflection and bending moment profiles along the pile are presented. A back analysis using a one-dimensional finite element computer program is conducted to evaluate the pile performance. In addition, the effect of top soil stratum on the pile performance is investigated. INTRODUCTION There have been considerable work reported on the behaviour of axially loaded rock socketed piles, see for example Leung (1996). On the contrary, there are relatively few case histories reported on the performance of laterally loaded socketed piles. In the course of several major construction projects in Singapore, a good number of cast-in-situ concrete bored piles were laterally load tested to failure. These piles were installed in silty clay/clayey silt/sand of various depths and subsequently socketed in granite or sedimentary rock of different socket lengths. The pile performance was evaluated using a one-dimensional finite element computer program. The Subgrade Reaction method was employed to establish the correlation between the subgrade modulus and the soil/rock parameters by back analysing the linear portion of lateral load-deflection responses of the test piles. An elasto-plastic model is then employed to predict the non-linear load-deflection behaviour of the piles. The performance of the laterally loaded socketed piles and the results of the back analysis are presented in this paper. FINITE ELEMENT ANALYSIS A one-dimensional finite-element analysis (Leung and Chow, 1987) is employed to predict the deflection of a laterally loaded pile. A computer program is written to incorporate the analysis whereby the pile is discretized into elements to take into account the different soil strata.