ABSTRACT: Soil nailing is an earth retaining technique used to stabilise existing slopes and support excavations. The stability post construction can change due to variation in groundwater, resulting in a reduction of effective stress in the soil. Nine centrifuge model experiments were performed investigating the influence of reducing the effective stress within the model by water inundation. The models tested were 1/10th scale. The full-scale prototype excavation was a three metre high cutting with a slope angle of 70°. The corresponding forces developed in the nails and displacements developed are assessed. INTRODUCTION Soil nailing is an earth retaining technique used to stabilise existing slopes and support excavations, both as temporary and permanent works. The long term stability of the excavation post construction can change due to a number of factors, i.e. nail degradation, failure of the facing. One particular aspect is changes of groundwater resulting in changes of effective stress conditions in the soil. The long-term performance of soil nailed excavations is a major unknown to those designing the soil nail systems because there are very few over 20 years old. Those observed for long-term performance have been monitored for a period typically 2–5 years after construction (FHWA, 1996). Hence, the response of the soil nailed structure to changes in ground conditions within the soil are not well established. The aim of these studies was to investigate the contribution made by soil nails to maintaining the stability of a steep sided cutting during the excavation process and a period of water inundation. The technique of centrifuge modelling was used to investigate the processes. The investigation considers the influence of changes in effective stress conditions on the stability of the slope and the increased contribution of the nails to maintain stability under these conditions.

ABSTRACT: Building a high embankment on soft alluvial deposits within the constraint of a short construction period has always posed challenges to geotechnical engineers. Other than stability, settlement of the embankment has to be controlled. In the construction of a bridge embankment project in Singapore, embankment piles were used to ensure the stability of an embankment during construction, and to reduce and control subsequent settlements of the embankment. A system of embankment piles, integrating a flat slab, capping beams and geotextile was constructed. The capping beam-pile system that was implemented differs from the conventional practice where piles with individual pile caps are used. The capping beams were constructed perpendicular to the longitudinal axis of the embankment. This paper describes the study on the load transfer of the road embankment supported on embankment piles. The loads on the capping beams and soft ground were recorded and compared with theoretical analyses, based on equilibrium of semicylindrical sand arches. The field results showed reasonable agreement with the theoretical model. The comparison between the field results is also discussed in the paper. INTRODUCTION Soft marine and peaty clays of very low shear strength and high compressibility have been posing numerous foundation problems in Singapore. Embankment fills on such clays are often associated with potentially large ground movements and stability problems. When an embankment is formed on these clays, which have very low shear strengths, the increased stresses in the soft soil strata may lead to a deep-seated slip failure, causing large ground deformations. Piles are sometimes used as a ground improvement technique, in order to support the embankment fill. With the partial weight transfer of the overburden, the stresses acting on the soft ground will be reduced, thereby leading to greater stability and less settlement of the embankment fill.

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: Many unstable slopes with active or potentially active slides are limiting factors in urban planning, and urban, traffic and other development on the Danube river bank (right) in Yugoslavia from Belgrade to the state border. Because of complex lithological structures, neotectonics, erosion and other current geodynamical processes in the area, a multidisciplinary approach to investigations is required and particularly needed for any local remedial or protection measures. Our numerous papers on engineering geological investigations on unstable slopes clearly show that we have not enough experience in the determination of groundwater table fluctuations, although its presence is one of the key active factors in slope stability. This paper puts an emphasis on the hydrogeological activities and methodology of a reliable, quality determination of the groundwater regime in the landslide body as a basis for geotechnical modelling of slope stability, all for the purpose of planning the Golden Hill farm estate development near the town of Smederevo, Yugoslavia, i.e. preparing optimum measures of protection. INTRODUCTION For the purpose of determining geotechnical parameters for local land development, vineyard raising, construction of access communications, subsidiary buildings, an optimum irrigation system and drainage systems in the overhumid zones in the area of Golden Hill farm estate near Smederevo, which is fully situated in the central part of the "Plavinac" landslide, a program of specific, dedicated, hydrogeological and engineering geological investigations, in the office and in the field, was first defined and then implemented. In the final phase the ground stability was to be modelled using different groundwater tables, and protection measures of the level of a detailed design were to be planned in order to arrange and develop the land on an area of about 31 hectares.

ABSTRACT: The paper discusses the possibility of using the principles of bionics for designing reinforced earth embankments. Practical usage and novelty of proposed approach are shown on the example of number of patented concrete constructions. The results of model tests (method of equivalent material) and computer calculations (Finite Element Method – 2D, Limit Equilibrium Method – 3D), confirm high efficiency of proposed approach. INTRODUCTION Due to wide use of reinforced soil technology in recent years the problem established of effective methods for optimization of the structures and reduction of cost of construction has become real. PRINCIPLE OF EQUALITY IN STRENGTH Stressed-strained state (SSS) of the embankment is characterized by high irregularity both in longitudinal and transversal directions. In this state the strength properties of the materials in different parts of the embankment are used to various degrees. In this case the principle of equality in strength requires to select materials (soil and reinforcement) in such a way that their spatial arrangement should provide uniform SSS and should allow full use of their strength. In general, the solution of this problem is associated with many difficulties and it should be divided into several stages. Improvement of equality of strength as far as the height of the embankment is concerned (plain task, cross section) In order to work out the recommendations as far as rational distribution of reinforcement along the height of the embankment is concerned we have carried out three series of computations using "ARMDAM" program (finite element method, plain deformed state, written by the authors). In the first series of computations the criteria of evaluation of reinforcement efficacy were determined. For this purpose the height position of one layer of reinforcement has been changed and the embankment SSS has been analysed.

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: The technique of a soil nailed wall in a soft soil area for deep excavation was developed in this paper. Soil nailed walls are generally used to reinforce clay, residual soil, sand and angular soil etc. In recent years, they have been adopted for deep excavations by reinforcing soft soil such as muck and mucky clay. The design method of a soil nailed wall on excavations in a soft soil area is presented. The mechanism of the structure and retaining effect is analyzed. A case history for a depth of excavation is 5.0m is presented. If the capacity of foundation pit basal soil is low, vertical strengthening needs to be introduced. These retaining structures can be used for the excavation in depths of 3m-7m soft soil areas. INTRODUCTION Fuzhou is a soft soil area that is located on the southeast coast of China. During this decade, many new high-rise buildings have been constructed. Generally 1 or 2 levels of basements are common for high-rise buildings, and excavation depth is 3.5m–10m. The retaining and protecting for excavations of deep foundation pit therefore becomes more important. The technique of a soil nailed wall (also named combined shotcrete-anchorage-netting reinforcement technique in local area) is the slope retaining technique that the soil nail is the main force structure and is installed across the potential failure surface. It consists of in-situ stabilized soil body, a shotcrete facing and necessary waterproof system. The retained soil mass is drilled and a steel bar or steel pipe is put into the drill hole and grouting is used 1 or 2 times. Steel mesh is then installed and concrete facing is sprayed to make the soil nail and shotcrete facing a bond. It was previously considered not suitable for use on soft soil ground.

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: Landslide in intensive seismic zone has its peculiar features. Some slope may be stable under static load (normal state). When the slope is in limit equilibrium state, even a slight earthquake may trigger it to destabilize. An intensive earthquake may directly cause a whole slope to fail. Kangding City is located in the intersection of three famous active seismic belts and thus with frequent earthquake activity. Many earthquakes occurred there in the past and the basic earthquake intensity is IX degree. Frequent earthquake activity directly influences the slope stability in the region, earthquake is the key factor inducing landslide and rockfall. In view of this, dynamic discrete element method (DDEM) is adopted in analyzing the stability of a slope in Kangding City, emphasis is laid on modeling of seismic effects on slope stability. The modeling results indicate that even an earthquake with intensity V degree is enough to cause the front slope to slide, earthquake with intensity IX degree will makes the whole slope to fail and slide. The harnessing engineering is quite effective to earthquake with intensity less than V degree. However, when earthquake with intensity IX degree occurs, the bolting engineering in the steep part will be destroyed first and then the slide-resistant piles and finally the whole slope. INTRODUCTION Baitukan landslide is situated at the east slope of Shaoxiangping, along the left bank of Zeduo river in the vicinity of Kangding City, which is located at the intersection of three active seismic belts, thus with frequent earthquake activities. The landslide is an old rockslide of tremendous dimension. Its length is about 600m and width is about 1300 m. Due to lateral erosion of the Zeduo River, the frontal part of the landslide deposits failed frequently. On 15th June 1995, Kangding City hit by a strong rainstorm.

SUMMARY: We performed a series of laboratory experiments using a large-scaled rainfall simulator and the stability analyses, in order to obtain the quantitative evaluations of the effects of vegetation on a face of slope. As the results of the experiments, we could obtain the quantitative relationship between a intensity of rainfall and a ratio of partial interception loss by vegetation, and also the evaporation and evapo-transpiration ratios could be calculated out from the observed weighing data. Based on the suctions measured during the experiments, the vertical distribution of soil-moisture could be numerically calculated, so that, the time-dependent slope model was represented by the obtained moisture distribution of each time-step, using the assumed relationship of the saturation degree and the corresponding shear strength. After the stability analyses were carried out against these slope models, the time-dependent changes of factors of safety were compared with the obtained evapo-transpiration ratios to exam the correlation of stability and water-uptake by vegetation. It was pointed out that the abilities of vegetation to intercept rainwater partially and to dry the soil as uptake can contribute stability of slope even partially depending on the meteorological situation and initial condition of soils. Finally, we could indicate the effects of vegetation on slope quantitatively as the stability of slope during/after rainfall through the experiments and analyses. INTRODUCTION Earth structures are often applied for construction works of infrastructures, and actually often constructed at the sites along railways in Japan. For these structures, the surface treatment on the face of a slope should be required to prevent surficial sloughing and erosion by surface runoff. Depending on the circumstances surrounding the interested railway sites, the aesthetic impression for the public also tends to result in giving a high advantage to the choice of the vegetation as a surface treatment.

ABSTRACT: Geotextiles have been extensively used in hydraulic structures as revetment filters subjected to wave loads. The alternating flow through the geotextile creates a flow regime very different from the unidirectional flow condition that has been extensively studied. The stability of the revetment system depends on many factors, such as the hydraulic properties of geotextile, the initial placement condition, particle size distribution of the subsoil, and the intensity of the wave loads. A new laboratory apparatus has been developed to investigate the influence of the hydraulic conditions on the behavior of soil-geotextile interaction and the stability of the revetment system. This apparatus is capable of simulating cyclic flow conditions normal to the soil-geotextile interface. Two series of tests have been conducted using this apparatus and preliminary test results are presented and discussed in this paper. INTRODUCTION The main role of the geotextile as a filter in hydraulic structures such as revetments is to prevent the erosion of the subsoil, while allowing the free drainage of water across the revetments. Hence, the pore size of geotextile should be small enough to retain the soil particles, while large enough for free passage of water. Preferably, the performance of these geotextiles under active wave action has to be evaluated instead of unidirectional flow conditions. Conventional filtration criteria for geotextiles, established for steady flow conditions, state that for a uniformly graded soil, geotextile opening size must be smaller than a characteristic diameter of base soil, say D85 (some times this criterion also involves relative density of subsoil, coefficient of uniformity, etc.). In unsteady flow conditions, the stability of the revetment system depends on many factors, such as the hydraulic properties of geotextile, the grain size distribution and the initial condition of the subsoil, as well as the intensity of the wave loads.

ABSTRACT: Citatah landslide was indicated at the section of Km 23, from Bandung Ð Jakarta main road, West Java, Indonesia. Its dimension is approximately 200 m long located at the medium to steep morphology. This present activity affects the roadway, which pass through the landslide body. The detail engineering geological and geophysical investigation have been done in order to study the behaviour of soil and rock creep at Citatah landslide. Resistivity analysis shows that the unstable soil layer has resistivity between 23 Ð 25 W m, the interlayer of clay, silt and sandstone have resistivity between 7 Ð 17 W m, claystone between 2 Ð 7 W m, and andesitic rock, as a sill, is between 40 Ð 85 W m. The rock analysis observed from shallow drilling hole shows correlation with the resistivity of the rock types. The layer of claystone found at the depth of 9 m, within bore hole 1, is indicated the value of resistivity between 3 Ð 7 W m. Within bore hole 2, claystone found at the depth of 14 m. These claystone layers are interpreted as sliding planes. This result of investigation could be considered for the mitigation of landslide around this area. So the proposed road is suggested to be placed on the andesitic rock which is situated in between the claystone layers belong to Batuasih formation. INTRODUCTION Most of Indonesian areas were covered by the youngest formation of the Quaternary deposits. Moreover, the volcanic belt passing through Sumatera and Java islands, Nusa Tenggara and Maluku archipelagos, and North Sulawesi, creates many unstable areas which may cause geological hazards including land movement. The Citatah area, in which the study was carried out, located at West Java Province, passed by road connecting Jakarta and Bandung. This area constitutes one of landslide zones in West Java.

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: 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.

ABSTRACT: Strata behavior and control in inclined coal seam face are studied with the following methods: field monitoring of strata behavior is carried out at a working face; Model test on equivalent material is made along dip direction of face and both strata movement and stress redistribution are analyzed and described; Overlying strata movement and fracture are modeled by discrete element method (DEM). The following conclusions may be drawn: Inclined dip angle of coal seam leads to asymmetry of the movement and fracture of overlying strata as well as the abutment pressure distribution; The gob is filled with caved debris differently; the lower end is fully packed, whereas the upper end is however in vacant condition. In the dip direction, the roof is supported by the caved debris quite differently, which results in differentiate roof deflection. The roof at the lower part will not break, but will certainly break at the upper face end, which leads to intensive strata movement in the upper end; Roof movement is much more remarkable in inclined coal seam than that in gently inclined seam. It is therefore strongly recommended that the supports in longwall working face be set with higher stability to keep them sound. INTRODUCTION Meanwhile the rolling blocks may have impact action to the face support; (2) Face floor may fail and shear displacement may occur along bedding plane in sip direction, which as a results has negative effects on support stability; (3) Due to uneven filling of gob by the caved debris, roof behaves quite differently in the dip direction characterized by intensive roof movement at the middle and upper section; (4) More remarkable anisotropy rockmass, which makes gateway deform and fail with distinguished direction.

ABSTRACT: Engineering geologists and geotechnical engineers often have to deal with problems of stability of natural or man-made slopes built up by jointed and weathered rock mass. This paper deals with the stability conditions of an important rhyolite cliff, the stability of which has endangered human life, a state road and a brewery below it. Several methods used for the investigation and for the stability assessment of the cliff are described which had to take into account the complex rock mass conditions. Methods of terrestrial photogrammetry have been used in the investigation. They enable monitoring of slope deformations and they have contributed to the selection of effective, economically acceptable mitigation methods. After assessing all investigation results effective and economically profitable remedial measures have been chosen. GEOLOGICAL AND GEOMORPHOLOGICAL CONDITIONS The rhyolite cliff is located in the village of Vyhne, on the boundary of Štiavnické vrchy Mountains, in Central Slovakia (Figure 1). The cliff is about 75 metres long and about 23 to 29 metres high (Figure 2). It is formed by neovolcanic rocks of Central Slovakia, originating as large rock bodies, of frequently different volcanic structure. Stratovolcanic structures typically prevail. The volcanic activity was limited to Badenian and Sarmatian periods (Tertiary-Neogene), related to dissection and disintegration of the volcanic bodies into individual structural blocks. During the end of the Sarmatian to Lower Pannonian periods (Neogene), the rhyolite volcanic activities were renewed. Channels of the rhyolite lava were formed along the well developed fault systems. The volcanic body represents an extrusion of a laccolith type penetrating the older Sarmatian rocks, characterised by a high viscosity and explosive behaviour. From the view point of lithology it is a rock type of rhyolite with secondary feldspar. The rhyolite was the subject to extensive denudation in the Pannonian period.

ABSTRACT: In this study, the stability analysis of slope failure that occasionally occurs when rain falls was carried out. This paper focuses especially on the stability of large-scale cut slope exposed to heavy rainfalls. The study was carried out on a cut slope which is 52 meters high and consists of soil and rock. Gradual landsliding is in progress due to continual heavy rainfalls. This paper describes slope stability analyses performed to assess the appropriate methods of stabilization. For the numerical analyses, the slopes were divided into several parts by soil layers, slope height, and the scale of the landslide. As a result, two different types of stabilization methods are recommended according to the condition of the cut slope and the working area. For slopes with relatively low height and enough working area, it is recommended that retaining walls are constructed at the lower end of the cut slope and soil-nailing method is applied to flatten the slope. For the other slopes, soil-nailing method is recommended. INTRODUCTION At a highway construction site in the middle west part of Korea, landslides of large-scale soil and rock slopes have occurred due to intense rainfalls. Therefore, proper stabilization methods were required to allow construction continue. The studied slopes are largely excavated ones, which consist of soil and rock layers. Landslides were gradually developing, so the exact areas of landslide and future movements were unpredictable. Based on the information gained from geologic site exploration of the failed slopes, the slopes were divided into several cross-sections (zones for analysis). For each cross section, slope stability analysis was carried out and suitable stabilization methods were proposed. SITE AND SLOPE CONDITION According to geological investigation, from the ground surface the distribution of strata is alluvial soil layer, weathered soil, weathered rock and soft rock.

ABSTRACT: The geotechnical factors controlling the design of the open pit slopes of the Pasminco Century Mine near Lawn Hill, Queensland are presented below. Pasminco Century is a stratiform shale hosted zinc deposit in the Lawn Hill Formation which is overlain in part by the Thorntonia Limestone Formation. The deposit is located in a structurally complex regime that consists of a synclinal basin truncated by easterly striking reverse faults through its centre and northern and southern limits and by an unconformity on its eastern and western margins. Deposit geometry and slope stability is further complicated by small scale folding, a pattern of northeast and southeast striking subvertical faults and northeast dipping thrust faults. Fault emplaced blocks of Lawn Hill Formation occur in the limestone overburden. A staged mining approach has been adopted with the excavation of final pit walls around the deposit margins and interim pit walls along the internal boundaries between adjacent stages. Deposit geometry, major discontinuities and groundwater pressure controls the design of the interim and final pit walls. Two and three dimensional limit equilibrium stability analyses were conducted using both deterministic and probabilistic approaches to determine appropriate pit wall design criteria and to select a suitable excavation sequence and schedule. Interim western walls in the northern ore block are extremely sensitive to wall location, inclination and excavation schedule due to deposit geometry and low residual shear strength along tuffaceous clay beds. INTRODUCTION Geotechnical assessment for design of the Pasminco Century Mine open pit slopes commenced in 1991 with the introduction of a basic geotechnical logging system and the establishment of a database for all cored boreholes drilled on the deposit. The level of geotechnical data collection and input into pit design increased as the deposit investigation advanced into detailed feasibility studies.

ABSTRACT: A series of laboratory slope failure experiments was conducted to elucidate the initiation of rainfall-induced slope failures from moisture content measurement records. The change in moisture content during the infiltration of rainwater and at initiation of slope failures was monitored by moisture sensors (Amplitude Domain Reflectrometry type). Prior to experiments, numerical unsteady seepage analyses were also conducted to identify the hydraulic response of the soil slope models to rainfall. The experiment results showed that slope failures were initiated by the increase in moisture content of the soil at the toe of the slope. Moisture content of the soil was noted to reach its saturated value at the time of failure. This indicates that rainfall-induced slope failure is a consequence of instability of the toe of the slope induced by saturation process under drained condition, and the major portion of the sliding mass may still be in an unsaturated condition. The experiments reported in this Paper also indicated that the direct measurements of change in moisture content could provide a great possibility in predicting the critical time of the initiation of rainfallinduced slope failures. Therefore, the results of applying any moisture sensors to predict and to monitor slope movements are encouraging. INTRODUCTION Rainfall-induced slope failure is one of the most destructive natural hazards, which can occur in a matter of seconds, and without warning during a prolonged heavy rain. Most slope failures always take place annually in Japan during the rainy season in the month of June when the rainfall intensity can reach up to 100 mm/hr. The disasters have claimed untold numbers of human lives and million dollars in infrastructure losses every year in many parts of the world. In Indonesia, for example, during the last eight years, there have been about 537 lives lost due to slope failures.

ABSTRACT: The stability of a talus slope along a section of an existing highway was investigated. This highway section was on routes US 22 and 322 located at the Lewistown Narrows in the state of Pennsylvania. For the investigation, subsurface explorations involving borings, seismic refraction survey, and very low frequency (VLF) radio wave measurements were conducted. Also, piezometers and inclinometers were installed to monitor groundwater level and creep, respectively. The talus slope was analyzed on a PC using Bishop's Simplified Method of analysis for both probable maximum flood and 100-year flood conditions. Results of the analysis indicated that the slope was stable even under the 100-year flood condition. However, there were concerns over water ponding and creep effects on the talus slope stability. Various remedial measures were proposed to enhance the stability of the slope. INTRODUCTION In the state of Pennsylvania, USA, routes US 22 and 322 are major highways leading to the state capital. Near the capital, these two routes merge and carry heavy traffic. A portion of the merged and heavily trafficked highway is located between the Juniata River on the south and a steep slope of Shade Mountain on the north, in what is known as the Lewistown Narrows. As the name implies, the Juniata River Valley in this section is very narrow, being confined by the steep slopes of Shade Mountain on the north and Blue Mountain on the south. The Shade Mountain slope is very steep and the lower portion of the slope is generally covered with talus. Because this section of highway (approximately 9.5 km long) has only two lanes, one in each direction, a four-lane, limited access, bifurcated roadway on the talus slope is planned to accommodate the heavy traffic and improve safety within this restricted area.