Soil mechanics fact finding survey, progress report. Cooperative triaxial shear research program of the Corps of Engineers,

At head of title: War Department, Corps of Engineers, Mississippi River Commission.

Bibliography on soil mechanics 1940-1944,

Cover title.

Proposta de consolidació d'un talús a l'estadi municipal de futbol de Montilivi (Girona)

L’estudi pretén comprovar que el talús adjacent a la grada est de l’Estadimunicipal de Montilivi no és estable i posteriorment proposar una mesura correctora, dimensionar-la i comprovar-la amb un programa d’ordinador específic Els antecedents al problema són els següents: A la ciutat de Girona, concretament al barri de Montilivi existeix un problemàtica que es va reiterant any rere any. Degut a les característiques geomecàniques del seu subsòl, argiles expansives, quan s’augmenta les condicions d’humitat del terreny, es produeix una solifluxió del terreny i desencadena en esllavissades. S’hi ha intentat posar solució però el fet és que només s’ha apedaçat el problema. A l’any 1996 es produeix la primera esllavissada del talús. S’ensorra la grada preferent del camp del Girona. El 7 de maig de 2004. Un nou esfondrament a la grada est de l’estadi que afecta al nou vial d’accés a la Universitat de Girona. Finalment, i després de la gran nevada del 2010, es produeix una nova esllavissada en elrecinte de l’obra d’ampliació de l’estadi de Montilivi

Armourstone revetments : will standard design criteria prevent failure? /

Bank stabilization structures are used to prevent the loss of valuable land within the urban environment and the decision for the type of structure used depends on the properties of the stream. In the urban areas of Southern Ontario there is a preference for the use of armourstone blocks as bank stabilization. The armourstone revetment is a free standing stone structure with large blocks of stone layered vertically and offset from one another. During fieldwork at Forty Mile Creek in Grimsby, Ontario armourstone failure was identified by the removal of two stones within one column from the wall. Since the footer stones were still in place, toe scour was eliminated as a cause of failure. Through theoretical, field, and experimental work the process of suction has been identified as a mode of failure for the armourstone wall and the process of suction works similarly to quarrying large blocks of rock off bedrock streambeds. The theory of lateral suction has previously not been taken into consideration for the design of these walls. The physical and hydraulic evidence found in the field and studied during experimental work indicate that the armourstone wall is vulnerable to the process of suction. The forces exerted by the flow and the resistance of the block determine the stability of the armourstone block within the wall. The design of the armourstone wall, high surface velocities, and short pulses of faster flowing water within the profile could contribute to armourstone failure by providing the forces needed for suction to occur, therefore adjustments to the design of the wall should be made in order to limit the effect.

Centrifuge Modeling of Sandy Slopes

Slope failure occurs in many areas throughout the world and it becomes an important problem when it interferes with human activity, in which disasters provoke loss of life and property damage. In this research we investigate the slope failure through the centrifuge modeling, where a reduced-scale model, N times smaller than the full-scale (prototype), is used whereas the acceleration is increased by N times (compared with the gravity acceleration) to preserve the stress and the strain behavior. The aims of this research “Centrifuge modeling of sandy slopes” are in extreme synthesis: 1) test the reliability of the centrifuge modeling as a tool to investigate the behavior of a sandy slope failure; 2) understand how the failure mechanism is affected by changing the slope angle and obtain useful information for the design. In order to achieve this scope we arranged the work as follows: Chapter one: centrifuge modeling of slope failure. In this chapter we provide a general view about the context in which we are working on. Basically we explain what is a slope failure, how it happens and which are the tools available to investigate this phenomenon. Afterwards we introduce the technology used to study this topic, that is the geotechnical centrifuge. Chapter two: testing apparatus. In the first section of this chapter we describe all the procedures and facilities used to perform a test in the centrifuge. Then we explain the characteristics of the soil (Nevada sand), like the dry unit weight, water content, relative density, and its strength parameters (c,φ), which have been calculated in laboratory through the triaxial test. Chapter three: centrifuge tests. In this part of the document are presented all the results from the tests done in centrifuge. When we talk about results we refer to the acceleration at failure for each model tested and its failure surface. In our case study we tested models with the same soil and geometric characteristics but different angles. The angles tested in this research were: 60°, 75° and 90°. Chapter four: slope stability analysis. We introduce the features and the concept of the software: ReSSA (2.0). This software allows us to calculate the theoretical failure surfaces of the prototypes. Then we show in this section the comparisons between the experimental failure surfaces of the prototype, traced in the laboratory, and the one calculated by the software. Chapter five: conclusion. The conclusion of the research presents the results obtained in relation to the two main aims, mentioned above.

Behaviour of displacement, cast-in-place piles on collapsible soil

The paper presents the results of instrumented compression load tests carried out in three uncased cast-in-place piles (pounded piles, called apiloadas in Brazil) which is largely used in interior part of the state of São Paulo. The tests were conducted with the soil in the natural condition and after soaking with water, before loading, in order to evaluate the influence of the soil collapsibility in the results. The values of the ultimate loads (total, point and lateral loads) obtained in the tests are presented and compared with the values predicted by empirical methods that utilize SPT and CPT results.

Specific depth cone resistivity measurements to determine soil engineering properties

The University of British Columbia (UBC) began performing piezocone penetration tests (CPTU) with electrical resistivity measurements (RCPTU) in 1989. Since then, RCPTU research at UBC has focused on obtaining geo-environmental parameters such as fluid resistivity and soil engineering properties such as porosity and degree of saturation from measurements of bulk soil electrical resistivity using the empirical relationship proposed by Archie (1942). Within this framework, the paper illustrates and discusses important design and calibration issues for resistivity modules such as the use of isolated circuitry to achieve linear calibrations over large ranges of resistivity. The suitability of RCPTU measurements for determination of geo-environmental and geotechnical parameters are assessed using typical ranges of soil and groundwater properties and methods of isolating individual factors for study are discussed. Illustrative examples of RCPTU research efforts including the environmental characterization of mine tailings, delineation of saline water intrusions in fresh water aquifers and the quality control of geotechnical ground densification are presented throughout the text. It is shown that groundwater temperature and hence ion mobility is not significantly altered by frictional heat generated during piezocone penetration and that ratio-based approaches to monitoring soil porosity can be used to eliminate the requirement for extensive groundwater sampling programs. Lastly, it is shown that RCPTU measurements above the water table can only be made using resistivity modules that are stable over a large range of resistivities and that such measurements are the most difficult to interpret because of grain surface conduction effects and generally unknown fluid resistivities.

Aspects of Mechanical Behavior and Modeling of a Tropical Unsaturated Soil

The research studies the applicability of two elastoplastic models for the collapse prediction of the lateritic soil profile from Southeastern Brazil. These tropical soils have peculiar geotechnical behavior, due to their mineralogical composition and porous structure coming from intense process of formation. Two elastoplastic models were analyzed: the Barcelona Basic Model (BBM) and another one based on BBM, however developed for tropical soils. Oedometric tests with suction control were performed at three distinct depths of the soil profile. The BBM was not suitable for the upper layer of the soil profile, because BBM considers the compressible behavior of the soil in function of the reduction of the elastoplastic compressibility index with the increase of the matric suction. The model developed for tropical soils showed better suited to the compressible behavior of the soil profile, resulting in good prediction of the collapse potential, mainly by accepting increasing values of the elastoplastic compressibility index of the soil profile with the matric suction rise. © 2013 Springer Science+Business Media Dordrecht.

Evaluation of Electrical Resistivity in a Tropical Sandy Soil Compacted

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identification of pore spaces in 3D CT soil images using a PFCM partitional clustering

Recent advances in non-destructive imaging techniques, such as X-ray computed tomography (CT), make it possible to analyse pore space features from the direct visualisation from soil structures. A quantitative characterisation of the three-dimensional solid-pore architecture is important to understand soil mechanics, as they relate to the control of biological, chemical, and physical processes across scales. This analysis technique therefore offers an opportunity to better interpret soil strata, as new and relevant information can be obtained. In this work, we propose an approach to automatically identify the pore structure of a set of 200-2D images that represent slices of an original 3D CT image of a soil sample, which can be accomplished through non-linear enhancement of the pixel grey levels and an image segmentation based on a PFCM (Possibilistic Fuzzy C-Means) algorithm. Once the solids and pore spaces have been identified, the set of 200-2D images is then used to reconstruct an approximation of the soil sample by projecting only the pore spaces. This reconstruction shows the structure of the soil and its pores, which become more bounded, less bounded, or unbounded with changes in depth. If the soil sample image quality is sufficiently favourable in terms of contrast, noise and sharpness, the pore identification is less complicated, and the PFCM clustering algorithm can be used without additional processing; otherwise, images require pre-processing before using this algorithm. Promising results were obtained with four soil samples, the first of which was used to show the algorithm validity and the additional three were used to demonstrate the robustness of our proposal. The methodology we present here can better detect the solid soil and pore spaces on CT images, enabling the generation of better 2D?3D representations of pore structures from segmented 2D images.

Values of the deformation modulus of soil at different ways of determining this amount

In accordance with Russian, Kazakh and European building regulations, the deformation modulus of soil should be determined in the laboratory and also apply in situ soil tests on the stages of engineering geology prospecting. In this paper we present data on the determination and adjustment of the deformation characteristics at different stages of construction

Durability/corrosion of soil reinforced structures /

"December 1990."

The use of agricultural soil maps and the status of agricultural soil mapping in the United States. Presented at the Twenty-Eighth annual meeting, 1948.

Cover title: Engineering use of agricultural soil maps.