Geotechnical Parameters Research Articles

Evaluation of Geotechnical Parameters and Attributes of Amassoma Soil in Bayelsa State, South-south, Nigeria, Using Seismic Refraction Analysis as an Indicator for Its Engineering Strength Determination

In this paper, we have carried out analysis of seismic refraction data obtained from two locations around Amassoma and its environs in Bayelsa State, South-South, Central Niger Delta, Nigeria. The core objective of the study was to evaluate the elastic parameters and attributes of the soil and its geotechnical conditions in order to determine its soil strength to carry load . These geophysical parameters and attributes include the p-wave and s-wave velocities, Vp /Vs ratio, dynamic Poisson ratio σ, rigidity modulus μ, bulk incompressibility K, Young’s modulus E, lamda-rho (lame’s) attribute λρ, K/μ ratio, and E/μ ratio. The layer velocities were obtained as the inverse of the slope of the travel time versus geophone distance curves plotted with the available refraction data, while the layer thicknesses were obtained from the intercepts of the plots. The p-wave and s-wave velocities were used as inputs in various mathematical relations to obtain the elastic moduli and their ratios. The results obtained depict a two-layer model, with the mean p-wave velocities of the layers generally found to lie in the 218m/s - 392m/s range and mean s-wave velocities in the 128m/s -231m/s range. The Vp/Vs ratio (the lithology discriminator) has values lying between 1.699 and 1.7 and the dynamic Poisson ratio has values between 0.235 and 0.240 . The moduli have most of their values above 3.0 x 107 N/m2 and their ratios are clearly more than unity. Overall, these results show that the topsoil and underlying sediments in the study area which are composed mainly of clay and sandy clay can be described as well consolidated and competent geomaterials that can support foundation structures and loads placed on them. In the final analysis, all the results obtained were found to be in agreement with the values reported in the literature for the Niger Delta and across the globe. The seismic refraction method has therefore been shown in this study as an effective technique for assessing the geotechnical strength of the soil.

Precipitation Amounts Triggering Landslide Processes in the Western Part of the Nałęczów Plateau (Lublin Upland, Poland)

Abstract This study covers the western part of Poland’s loess Nałęczów Plateau (Kazimierz Dolny, Zbędowice). Mass movements in the Lublin Upland occur during periods of increased precipitation or after a snowy and cold winter. To date, there are no comprehensive studies on active (precipitation, hydrology, vegetation, land use, anthropogenic factors) or passive factors (lithology, slope angle) causing such geohazards in this region. This area’s formations are characterised by high sensitivity to even small changes in moisture content; thus, their geotechnical parameters deteriorate as a result of precipitation or rising groundwater levels. The calculations in this study were chosen to determine the time necessary for ground response to external factors, in addition to determining the impact of these factors on decreases in the factor of safety (FS). Based on calculations in GeoStudio software, the impacts of rainfall totals and duration on slope failure, interpreted as an event where the FS falls below 1.0, were analysed. Accordingly, the threshold rainfall value was determined as the total rainfall at the time of slope failure. The study’s results indicate that loess covers are characterised by average water permeability, relatively high internal friction angles and low cohesion, which, combined with high slope inclination, favour landslide formation even when the slope is only partially saturated. The most unfavourable stability conditions occur at the beginning of spring, indicating that loess stability is significantly affected by snowmelt and precipitation at the beginning of the vegetation season, as well as the occurrence of episodic intense precipitation during the summer.

A Fully-Self-Adaptive Harmony Search GMDH-Type Neural Network Algorithm to Estimate Shear-Wave Velocity in Porous Media

Shear wave velocity (VS) is one of the most important parameters in deep and surface studies and the estimation of geotechnical design parameters. This parameter is widely utilized to determine permeability and porosity, lithology, rock mechanical parameters, and fracture assessment. However, measuring this important parameter is either impossible or difficult due to the challenges related to horizontal and deviation wells or the difficulty in reaching cores. Artificial Intelligence (AI) techniques, especially Machine Learning (ML), have emerged as efficient approaches for dealing with such challenges. Therefore, considering the advantage of the ML, the current research proposes a novel Fully-Self-Adaptive Harmony Search—Group Method of Data Handling (GMDH)-type neural network, named FSHS-GMDH, to estimate the VS parameter. In this way, the Harmony Memory Consideration Rate (HMCR) and Pitch Adjustment Rate (PAR) parameters are calculated automatically. A novel method is also introduced to adjust the value of the Bandwidth (BW) parameter based on the cosine wave and each decision variable values. In addition, a variable-size harmony memory is proposed to enhance both the diversification and intensification. Our proposed FSHS-GMDH algorithm quickly explores the problem space and exploits the best regions at the late iterations. This algorithm allows for the training of the prediction model based on the P-wave velocity (VP) and the bulk density of rock (RHOB). Applying the proposed algorithm to a carbonate petroleum reservoir in the Persian Gulf demonstrates that it is capable of accurately estimating the VS parameter better than state-of-the-art machine learning methods in terms of the coefficient of determination (R2), Mean Square Error (MSE), and Root Mean Square Error (RMSE).

Estimating settlements due to tunnel boring machine excavation

Soft-ground tunnel boring machines (TBMs) are the preferred solution for the construction of long tunnels and linear infrastructure assets, especially in urban areas. TBMs allow the control of tunnel-face stability, minimising the effects on surrounding ground. Unfortunately, existing methods for the assessment of ground surface movements due to TBM tunnelling either utilise complex and computationally expensive numerical analyses or rely on simplistic volume-loss theories, which do not consider the characteristics of the ground and TBM operation. This paper presents a simple formulation to estimate the immediate surface settlement due to the applied TBM support pressure, based on an analogy with the hyperbolic behaviour of stress–strain curves of soils. The variables chosen to describe the ground movement were the maximum surface settlement and volume loss, while the TBM face support pressure is used to describe the tunnel internal support pressure. Uncertainties due to the inherent variability of geotechnical parameters were also considered, resulting in the definition of lower and upper boundaries. Data from a series of centrifuge test results, with and without tunnel-face reinforcement by forepoles, and a real-scale TBM case study were used to validate the proposed model. The analyses show that the proposed model adequately represented the observed settlement data.

Artificial Intelligence Model for Prediction of Local and Main FALL in caving Panel of Bord and Pillar Method of Mining

Depillaring with caving method of mining is a common practice in Indian coalfields and so is the occurrence of fall in goaf area, which can be considered as a boon in disguise as it allows wining of coal from large reserves but this becomes a curse just because of its unpredicted occurrence. Various empirical and statistical models are developed after idealization of several complicated mechanisms but they are not able to predict roof fall accurately especially in caving panels. Therefore, a new approach based on Artificial Intelligence is used to predict the sequence of local and main fall in caving panel taking into account a host of geotechnical and mining parameters of the mine. Mathematical equations and hidden calculations of artificial neural networks are known to have the capability of learning and analyzing records endlessly. Two different models have been deployed after optimal hyper parameter optimization to predict the occurrence of fall and to characterize the nature of fall (local or main) with considerable and reliable accuracy.

Risk-based methodology to optimize geotechnical site investigations in tunnel projects

The scope of geotechnical investigations in tunnel projects is generally driven by the allocated resources rather than the expected variability in the ground conditions. Uncertainties in ground conditions may lead to poor decisions in project planning and active risk management. This paper presents a systematic and rational methodology to identify priority locations of additional geotechnical investigations for soft ground tunneling applications based on tunnel risks, site conditions, and project-related constraints. The methodology is applied to the cutter tool wear risk and quantifies the uncertainty in soil abrasivity index (SAI), the relevant geotechnical parameter. Preliminary geotechnical investigation data and site conditions from an actual tunnel project in an urban environment are used to illustrate the proposed methodology and demonstrate its effectiveness. Pluri-Gaussian simulation and sequential Gaussian simulation are used to characterize the 3D spatial variability in soil units and soil abrasivity, respectively, along the tunnel alignment. The study integrates geospatial assessments of SAI uncertainty and consequences of tool wear to develop an R index map that delineates the impact of uncertainty in tool wear rate. Project constraints of drilling accessibility and budget are incorporated in the R index map to find locations of additional geotechnical investigations. The study simulates a virtual sampling of additional boreholes and quantifies the reduction in uncertainty in tool wear rate and tunnel boring machine (TBM) intervention locations. Additional investigation at priority locations is found to reduce cutterhead intervention location uncertainty by approximately 90 rings (160 m). Further, integrating the uncertainty in tool travel distance is found to influence the cutterhead intervention location uncertainty by approximately 40 rings.

A probability-based efficient assessment of seismic wave scattering in complex topography with geo-property uncertainty

There is great randomness in determining geotechnical parameters, resulting in an uncertain local site effect caused by seismic wave scattering such as valleys, hills, basins, etc. It is significant to develop the probability-based assessment method to quantify the local site effect considering the geo-property uncertainty. The multiplicative dimensional reduction method (M-DRM) is employed to approximate statistical moments of the response of the local topography with random parameters. A multi-dimensional random problem is converted into a series of deterministic analyses, solved by the boundary element method. The probability distribution estimation can be obtained based on the maximum entropy algorithm. This approach is used to solve the seismic wave scattering of fossil river courses under P-waves, and the applicability is verified compared to the Monte Carlo simulation. The results show that M-DRM can assess the seismic wave scattering by local topography with high efficiency. The seismic wave scattering inhomogeneously magnifies the geo-property uncertainty in wave propagation. The displacement variability is primarily related to the incident frequency, and the response under high-frequency P-waves has significant variability. It is the reason that the effect of the geo-property uncertainty on the peak ground acceleration is determined by the energy distribution of the incident wave.

Large Displacement Finite Element Modelling of the Screw Driving Sounding Test in Sandy Soil Using the Coupled Eulerian-Lagrangian Method

The Screw Driving Sounding (SDS) is a recently developed in-situ testing method for soil/site characterisation. To better understand the mechanism of testing, it is essential to create a simulation model for the SDS test to assist in better understanding the response and in improving the testing process, not to mention the development of empirical correlations to estimate geotechnical parameters for use in design. Complex problems involving large deformations are usually difficult to solve with the classical finite element (FE) method because large deformations can lead to large mesh distortions and contact problems. In this paper, a computational model using the finite element method is developed to simulate the drilling process involved in SDS tests; the Coupled Eulerian-Lagrangian (CEL) approach is used to deal with large deformation problems. The SDS drilling process in a sandy deposit with defined stress states (i.e., relative density and effective confining pressure) is simulated, and the SDS-derived parameters are monitored. Based on the simulation results, a chart was established to correlate the measured SDS parameter with the internal friction angle for different vertical effective overburden stresses. The derived chart is validated with the results of laboratory tests performed on samples taken from several sites in Christchurch, NZ, adjacent to the locations of the SDS tests. The results show that the CEL FE framework can model complex physical processes encountered during the SDS drilling. Moreover, the developed chart can be used to estimate the friction angle of the sandy soil based on the SDS-measured torque at a given depth.

Multivariate interrelatedness of geotechnical and petrophysical properties towards developing near-surface lithology clusters in a sedimentary terrain

The study reports the approach of interrelating geotechnical and petrophysical parameters to develop near-surface lithology clusters in a sedimentary terrain. Field-based and laboratory-based geophysical, geotechnical, and petrophysical measurements were carried out with a view to finding correlations among related parameters, grouping the parameters into depth clusters, and determining trend correlations between field-acquired and laboratory-obtained parameters. Four agglomerate hierarchical cluster signatures were identified at depth 0–30 cm, three at 30–60 cm, and five at 0–90 cm. Principal component 1 retained 74% of data variation and differentiated the petrophysical parameters according to Poisson’s ratio (v) and velocity ratio (Vp/Vs). Principal component 2 explained another 14% of variability in the original responses and separated parameters based on elastic modulus (E) and clay fraction (C). Degree of correlation of Vp/Vs with porosity (Φ), sand fraction (S), C, unconfined compressive strength (U), and California bearing ratio (R) followed order Φ > S > C, and U > R. Trend correlation of shear velocity at 1 m showed good agreement (R2 = 0.992) between field and laboratory data with an amplification factor of 4.13 separating the corresponding values. Lithology determined from soil analysis agreed with that inferred from measured electrical resistivity while geotechnical, petrophysical, and geophysical spatial analysis supported site lithology configuration patterns. Thus, multivariate association of geotechnical and petrophysical parameters exhibited potentials for rapid and exploratory near-surface lithology mapping even at a regional scale.

Integrated Resistivity, Index, and Strength Characteristics of Subgrade Soils: Implication for Highway Pavement Failure Studies in North-Central Nigeria

Integrated geophysical and geotechnical studies have been carried out to determine the geological cause(s) of the failure of sections of Ajaokuta – Anyigba Highway, North-central Nigeria. Forty-eight (48) Vertical Electrical Soundings (VES) were conducted on failed and stable sections of the highway. Also, twenty-one (21) subgrade soil samples close to VES stations from the unstable and stable sections of the highway were subjected to laboratory geotechnical analyses which include grain size distribution, Atterberg limits, compaction (Optimum Moisture Content, OMC, and Maximum Dry Density, MDD) and California bearing ratio (CBR) at soaked and unsoaked states following American Society for Testing and Material (ASTM) standards as appropriate. The geophysical results show that low resistivity (10–100 Ohms-m) inferred as clay/silt of low competence characterizes the subgrade soils of the unstable segment. While higher resistivity (148–272 Ohms-m) interpreted as sandy-clay/silt with moderate competence was obtained for the subgrade soils of the stable segment. Results of Geotechnical tests show that the subgrade soils of the unstable segment have geotechnical properties that generally fall below required standard specifications. Strong correlations of R = 0.86, 0.9, and –0.88 were obtained between CBR and sand, resistivity, and the amounts of fines, while a fairly strong correlation of R = –0.67 was obtained for the plasticity index. The high level of correlation implies that CBR can be predicted from geophysical data and other geotechnical parameters. The study has revealed that the advanced weathering of the underlying Mica-Schist to clayey/silty subgrades with unsuitable geophysical and geotechnical properties is a major contributor to the instability of the highway. Keywords: Atterberg limit; CBR; Grain size distribution; Resistivity; Subgrade soil.

A Practical Approach To Bridge Foundation Design

This paper aims to provide guidance on a process for the design of bridge foundations. It sets out a brief explanation of bridge terminology, and afterwards discusses aspects of the geotechnical investigation, foundation design, and construction specification for bridges. It is intended to assist engineers who may not be familiar with bridge design in gaining a working knowledge of the basic design principles and requirements. It is not intended as a detailed step-by-step procedure for foundation design itself, but rather as a framework for a systematic process of design. Among the aspects that are emphasized are the process of assessment of geotechnical design parameters, and the means by which the outputs from geotechnical analyses can be most effectively communicated to others involved in the design process, especially the structural engineers.

Multivariate geophysical index-based prediction of the compression index of fine-grained soil through nonlinear regression

The determination of consolidation settlement is highly significant in fine-grained soil. However, evaluating compression index (Cc) is time-consuming and cumbersome. For the approximate estimation of Cc, several correlations based on various geotechnical properties have been established, involving boreholes and sample extraction. In such circumstances, non-invasive geophysical techniques can provide a quick and cost-effective alternative in predicting the compression index. In this study, two geophysical techniques, namely electrical resistivity tomography (ERT) and multichannel analysis of surface waves (MASW), were coupled together to predict the compression index of fine-grained soil at Silchar, Assam, India. Electrical resistivity (R) and shear wave velocity (Vs) were determined from the ERT and MASW test respectively, and a nonlinear regression technique was employed to estimate the Cc. The R2 and RMSE values observed from the regression analysis are 0.874 and 0.036, respectively with R and Vs as independent variables. The multiple-geophysical index-based technique resulted in a 20% improvement in the R2 value of the nonlinear fit compared to that obtained using individual geophysical index-based predictions. The computation of statistical indices validates the regression results. Further, the geophysical index-based predictions of Cc were compared with the conventional method of determining Cc using the geotechnical parameters including liquid limit, water content, and void ratio. The concept and the proposed empirical equation can be implemented for different locations, thereby benefiting the researchers and the construction engineers.

Modification of Quaternary Clays Using Recycled Fines from Construction and Demolition Waste

Foundation of buildings in soft soil such as quaternary clay is often associated with difficult compaction, settlement, non-uniform and/or excessive deformation, and unsatisfactory shear resistance. The present study aims to assess the possibility of using recycled fines from construction and demolition waste, such as mechanically treated gypsum and waste concrete powder (WCP), instead of ordinary binders or industrial waste, in the stabilization of quaternary clay. A detailed characterization of soil components is presented. Seven mixes with various proportions of gypsum and WCP are prepared. Main geotechnical parameters of the modified soil are studied by applying standardized methods with a few deviations. XRD analysis and pH measurements are performed. It was found that the effect of 5% to 20% recycled di-hydrate gypsum is limited to improvement in moist soil compatibility. A gypsum content of 10% positively impacts soil cohesion and the oedometer modulus. WCP is an active component, containing non-hydrated cement, portlandite, calcite and calcium silicates hydrate. As a result, by adding 5% of WCP only, significant improvement can be achieved: greater soil cohesion, reduced deformability and higher UCS. When 5% of recycled gypsum is also added, soil cohesion is further improved because of ettringite formation.

Spatial characterization of seabed environmental conditions and geotechnical properties for the development of marine renewable energy in Sweden

Although knowledge of seabed properties is of high importance in selecting sites and determining technical designs and solutions for renewable energy offshore installations, it is often overlooked in marine spatial planning, owing to the absence of appropriate spatial analysis of these conditions. Identification and quantification of seabed conditions and geotechnical properties in finding safe and environmentally sustainable areas for installations of offshore renewable energy are therefore presented, using information produced in marine geological mapping. Six seabed environmental and 13 geotechnical parameters, which can be extracted from existing marine geological information and are of importance in analysing environmental conditions and planning designs are identified and presented, in addition to the suitability of various installation techniques for different areas on the Swedish seabed. Geographical information systems (GIS) are used to geospatially evaluate the different parameters in finding suitable locations and cable routes for a wave energy plant with gravity and/or suction caisson foundations. The presented categories and ranges of the environmental and geotechnical values for the various parameters have the possibility to be improved as new data are produced from future mapping. The parameters identified and presented here are valuable as they can be incorporated into multi-parameter evaluations for optimal site selection of different offshore installations. Supplementary material: The open geological information is available at http://www.sgu.se

Intelligent identification of soil and operation parameters in mechanised tunnelling by a hybrid model of artificial neural network-genetic algorithm (case study: Tabriz Metro Line 2)

ABSTRACT In this article, the ability of the artificial neural network-genetic algorithm (ANN-GA) to perform back analysis and predict maximum surface settlement in mechanised tunnelling is investigated. The required data of the ANN meta-model was generated using 150 three-dimensional finite-difference simulations. The global sensitivity analysis was performed on 19 parameters, including 17 geotechnical parameters of soil layers and 2 operational parameters of face pressure and grouting pressure. The predicted results using ANN were in good agreement with the numerical simulations so that R = 99% and rRMSE = 1.5% are obtained. Then, back analysis was performed using the ANN-GA hybrid algorithm and the geotechnical data of the monitoring point were updated using the maximum surface settlement monitored at this point. Also, for the geotechnical parameters considered in the design phase, using the same algorithm, the number of operational parameters required for optimal settlement was predicted.

Modified Meyerhof approach for forecasting reliable ultimate capacity of the large diameter bored piles

The static loading test is undoubtedly the most reliable method for forecasting the ultimate capacity of the large diameter bored piles (LDBP). However, in-situ loading of this class of piles until reaching failure is practically seldom due to the large amount of settlement required for shaft and base mobilization. Therefore, many international design standards recommend either capacity-based or settlement-based methods to estimate the LDBP ultimate capacity in case of the impossibility of performing loading tests during the design phase. However, those methods are invariably associated with various degrees of uncertainty resulting from several factors, as evidenced in several comparative analyses available in the literature. For instance, the settlement-based method of the Egyptian code of practice (ECP 202/4) usually underestimates the ultimate capacity of LDBP. In contrast, Meyerhof's capacity-based method often overestimates the LDBP’s ultimate capacity. In this paper, a modified approach has been proposed to forecast the ultimate capacity of the LDBP. This approach was modified from Meyerhof’s classical formula (1976) through three fundamental stages. First, an assessment study was performed to evaluate the reliability of the estimated LDBP ultimate capacity using Meyerhof’s classical method. For this purpose, results of full scale loaded to failure loading LDBP test and related twenty-eight parametric numerical models with various pile geometrical and soil geotechnical parameters have been used. Based on the assessment study findings, the essential modifications were suggested in the second stage to adapt Meyerhof’s classic method. In the third stage, the results of several numerical models and in-situ loading tests were employed to assess the accuracy of the developed modified method. This study showed that Meyerhof's classical method overestimated the ultimate capacity of LDBP with an error percentage ranging from 14 to 46%. On the other side, the proposed modified approach has succeeded in estimating the ultimate capacity of loaded to failure in-situ LDBP test and twenty numerical LDBP models with error percentages ranging from 0.267 to 7.75%.

A computational approach for 3D modeling and integration of heterogeneous geo-data

This paper tackles the volumetric representation of geophysical and geotechnical data, gathered during exploration surveys of the subsoil; in particular, we focus on the modeling and analysis of underwater deposits. The creation of a 3D model as support to geological interpretation has to take into account the heterogeneity of the input data, coming from offshore acquisition campaigns. Some data are massive, but cover the domain unevenly, e.g., along dense differently spaced lines, while others are very sparse, e.g., borehole locations with soil sampling and CPTU (Piezocone Penetration Test) locations.A automatic process is presented to generate the subsurfaces and volume defining a sub-seabed deposit, starting from the identification of relevant morphological features in seismic data. In particular, simplification and refinement based on geostatistics have been applied to generate regular 2D meshes from strongly anisotropic data, in order to improve the quality of the final 3D tetrahedral mesh. Furthermore, we also use geostatistics to predict geotechnical parameters from local surveys and estimate their distribution on the whole domain: in this way the 3D model will include relevant geological features of the deposit and allow extrapolating different geotechnical information with associated uncertainty. The volume characterization and its 3D inspection will support geological analysis and planning of future engineering activities. The developed methodology has been tested on two real case studies.

Characterization of the soil and rock hosting an aquifer with possible uses for drinking water and irrigation in SE Panama City using Geotechnical, Geophysical and Geochemical parameters

The supply of water to populations is a basic need that has been threatened more frequently in recent years due to climate change, which renders seeking other sources of water essential. The hydrochemistry of the groundwater of the aquifer located in the UTP Tocumen was characterized by previous research to determine its possible use as a source of drinking water and irrigation water. The objective of this study is to characterize the soil and rock hosting the aquifer to acquire more information about them with a view to possibly exploit an alternative source of drinking water. To this end, a 10-m-depth survey was conducted to obtain soil and rock samples from the area, and to characterize geotechnical and geochemical parameters. 2D electrical resistivity tomography was used to create a lithological model of the aquifer and to correlate the data. Soil is residual of the technosol type, considered permeable with a transmissivity level that favors rainwater infiltration, followed by the soil–rock interface, where rock is weathered. It´s followed by a sedimentary rock corresponding to marly siltstones with a certain degree of tectonic fractures that allow water infiltration and its accumulation in the rocks, constituting the aquifer. The 2D electrical resistivity suggests two water accumulations: a superficial and a deep one. There was a good correlation between the aquifer water’s chemistry and the rock geochemistry.

Geotechnical evaluation of non aedificandi areas susceptible to mass movements by pressuremetric tests

The present study investigated the susceptibilities to mass movements of slopes in areas classified as having high potential for natural accidents in Viçosa-MG-Brazil. Several stability scenarios were analyzed based on the geological-geotechnical characteristics of the terrain, considering resistance parameters and geometry for a two-dimensional analysis in the Geostudio Slope/W software. The research was based on an urban susceptibility map, which allowed the selection of areas with high potential for mass movement to carry out the PMT tests. These, in turn, subsidized the followed by numerical stability simulations to identify the degree of instability and the safety factor of the area in question. The PMT test was chosen for its speed and precision in obtaining the soil parameters in depth, which, associated with stability simulations, allowed an assessment of the slopes. In addition, scenarios were evaluated with geotechnical parameters obtained and the confidence interval was varied to increase the degree of safety of the evaluation. Finally, detailed information is provided, which can support public policies appropriate to each location, considering its geological-geotechnical peculiarities.

The mechanics of iron tailings from laboratory tests on reconstituted samples collected in post-mortem Dam I in Brumadinho

Dam B1 was approximately 85 m high and 700 m long along the crown when it suddenly failed in 25th of January, after 41 years of operations and deposition of tailings at the Paraopeba mining complex (Côrrego de Feijão), in Minas Gerais, Brazil. More than 250 people died and vast economic, social and environmental damages resulted from the collapse. Given the need to geotechnically characterise the tailings within the dam for a credible computational model of the failure, an extensive sampling and laboratory testing campaign took place. The geotechnical laboratory of the Civil Engineering Department at the Faculty of Engineering of the University of Porto (Portugal) was invited by CIMNE, under a contract with VALE, with MPF agreement, to conduct this program. This paper will present a description of the sampling campaigns in the remaining post-mortem dam/reservoir tailings were the failure instability mechanics developed and the experimental program undertaken to test the tailings in advanced laboratory tests. The results that embrace evaluations of the physical, hydraulic and mechanical properties, deduced from integral samples selectively collected and prepared as described, which allowed to define the geotechnical parameters necessary for the referred analyses are here resumed.