No description available.

The successful application of in-situ testing of soils heavily depends on development of methods of interpretation of the tests. The purpose of this thesis is to develop a consistent theoretical basis for the interpretation of pressuremeter tests in cohesive and frictional materials. The research programme is based on cavity expansion theory with additional details provided by a large strain finite element analysis. A unified analytical solution is developed for the expansion and contraction of both cylindrical and spherical cavities in dilatant elastic-plastic soils. For the first time, explicit solutions for the pressure-expansion and pressure-contraction relationships are derived without any restriction being imposed on the magnitude of the deformation. In addition, the finite element method is adopted for solving the cavity expansion problem. This is mainly due to the fact that only in special cases when simple material models and boundary conditions are involved has it been possible to solve the problem analytically. A finite element analysis of the cone-pressuremeter test in sand is described. A series of two-dimensional finite element calculations on both the self-boring pressuremeter test and the cone-pressuremeter test is performed. In modelling the penetration process of cone-pressuremeter tests, the stresses evaluated by the cavity expansion theory are used as the starting condition for the finite element analysis. Emphasis is placed on quantifying the effects of pressuremeter geometry on derived deformation and strength parameters. In the finite element formulation, a special effort is devoted to developing a lower order finite element suitable for analysing axisymmetric elastic-plastic problems which involve incompressibility constraints. The formulation of a new six-noded isoparametric displacement finite element is presented. To account for large strain (rotation) effects, an Eulerian description of deformation is adopted and the Jaumann stress rate is used in the soil constitutive equations. The suitability of the conventional interpretation methods for pressuremeter tests is critically assessed in the light of the finite element results. Based on the numerical results, improved procedures for obtaining in-situ soil parameters from pressuremeter tests in both clay and sand have been proposed.

Increasingly, tunnels are being planned in weak rock beneath urban areas in Australia and worldwide. Designers of these projects are required to predict the tunnel induced settlement so that an assessment of the possible effects on buildings and services above can be made. However, the existing methods for making such predictions require either a database of similar projects, or a knowledge of suitable parameters for use in numerical models. Numerical models of tunnelling are sensitive to model inputs. Some of these model inputs are irrelevant to the actual physical problem. The thesis discusses two key issues in solving elastoplastic tunnel problems, one being the inertial effects in finite difference methods, and the other being the mesh discretisation error. The causes and possible remedies for these is discussed, and an a priori predictive technique for discretisation error is developed. The method of choice for selecting parameters in numerical models is to use the backanalysis of a suitable pilot activity. However, traditional backanalysis methods suffer from non-uniqueness. The results of a backanalysis is not a single combination of parameters, but a zone in parameter space within which the fit to the observations is acceptable. The shape of this zone in parameter space is affected by the degree of correlation of the parameters, and by the non-linear nature of the problem. The technique of predictive analysis solves the problem of non-uniqueness in parameter estimation by backanalysis by choosing the point in parameter space which gives the most adverse prediction for the future construction, yet which maintains a reasonable fit to the pilot activity. The thesis uses three reference projects in Australia to show the techniques of backanalysis and predictive analysis. Cross sections of the Brisbane Rail Tunnels are backanalysed, and the resulting range in parameter space is discussed. For prediction of settlement in the New Southern Railway tunnel in Sydney, and the South East Transit project in Brisbane, the weak rock pressuremeter is proposed as a suitable and inexpensive pilot activity for the future tunnel construction. The results of the predictive analysis show that the method works. Therefore an improved method of predicting tunnel induced settlement in shallow tunnels is proposed, using the combination of numerical modelling, the weak rock pressuremeter and predictive analysis.

No description available.

The thesis is divided into seven parts. The first part is theoretical and consists of description of load-transfer method and its principal, description of load-transfer curves used for following inverse analysis and method for determining shaft friction in ß method. In the second part, there is an explanation of the determination of Ménard pressuremeter modulus from pressuremeter tests. The third part consists of the pressuremeter tests analysis and description of evaluating process of the pressuremeter modulus for different types of subsoil. In the fourth part states parametric study of load-transfer curves compiled on the basis of the pressuremeter tests, where we display an impact of input parameters on a load-settlement curves. The fifth part contains inverse analysis of pile load tests, which are set in similar geological conditions. Summary of used input parameters for individual load-transfer curves states in the sixth part. These parameters are responsible of achieving the best match of predicted and measured load-settlement curves. The last part is devoted to the thesis conclusion, which is the determination of parameters as inputs to the shape of load-transfer curves for bored piles with utilization of the pressuremeter tests.

The cone-pressuremeter is a new site investigation device which incorporates a pressuremeter behind a standard cone penetrometer tip. This dissertation is concerned with an understanding of the new device, and in particular the establishment of a detailed procedure to allow the test to be used to determine the engineering properties of cohesionless soils. A series of 34 calibration tests was performed, in which three cone-pressuremeter prototypes with cross-sectional areas corresponding to 15cm², 10cm² and 5cm² were used. The tests were carried out on cylindrical samples, enclosed in a chamber 1.0 m in diameter and 1.5 m in height. Stress controlled boundaries allowed independent control of vertical and horizontal stress in the range of 50 kPa to 300 kPa. A raining deposition technique was used to produce three sand densities, corresponding to loose, medium and dense samples. A programme of calibration was designed to provide an examination of the influence of relative density, stress level and stress ratio on cone-pressuremeter test data. Soil properties were related to the values of the limit pressure obtained from the pressuremeter test and the cone resistance values from the cone test. Empirical relationships were proposed for deriving density, friction angle and horizontal stress. Cone-pressuremeter tests were used for assessing directly the shear stiffness of the soil. A series of calibrations was needed to obtain the best possible estimation of the unload-reload shear modulus. Interpretation of the measured modulus was made by examining appropriate methods of calculating the modulus from unload-reload loops. Strain arm measurements and volume change measurements were compared. A method has been presented that allows the shear modulus values to be correlated to the relevant stress level acting around the pressuremeter during the test. The values of shear modulus obtained with the cone- pressuremeter were compatible with those obtained from the self-boring pressuremeter. An assessment of chamber size effects yielded useful information regarding the applicability of test correlations derived from calibration chambers to field problems. An additional study identified experimentally the influence of length to diameter ratio on the pressuremeter pressure-expansion curve.

abstract: Laterally-loaded short rigid drilled shaft foundations are the primary foundation used within the electric power transmission line industry. Performance of these laterally loaded foundations is dependent on modulus of the subsurface, which is directly measured by the Pressuremeter (PMT). The PMT test provides the lateral shear modulus at intermediate strains, an equivalent elastic modulus for lateral loading, which mimics the reaction of transmission line foundations within the elastic range of motion. The PMT test, however, is expensive to conduct and rarely performed. Correlations of PMT to blow counts and other index properties have been developed but these correlations have high variability and may result in unconservative foundation design. Variability in correlations is due, in part, because difference of the direction of the applied load and strain level between the correlated properties and the PMT. The geophysical shear wave velocity (S-wave velocity) as measured through refraction microtremor (ReMi) methods can be used as a measure of the small strain, shear modulus in the lateral direction. In theory, the intermediate strain modulus of the PMT is proportional to the small strain modulus of S-wave velocity. A correlation between intermediate strain and low strain moduli is developed here, based on geophysical surveys conducted at fourteen previous PMT testing locations throughout the Sonoran Desert of central Arizona. Additionally, seasonal variability in S-wave velocity of unsaturated soils is explored and impacts are identified for the use of the PMT correlation in transmission line foundation design. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2018

[pt] Para compreender as inúmeras variáveis que regem o comportamento tensão-deformação-resistência dos resíduos sólidos urbanos (RSU) muito se têm feito em laboratório na tentativa de modelar o que de fato acontece dentro das células de resíduos, com vários níveis de sucessos e insucessos. Entretanto, dificuldades na obtenção de amostras indeformadas ou na fabricação de amostras representativas da real condição de campo, podem ser fatores limitantes. Por outro lado, as técnicas diretas de investigação de campo trazem consigo o potencial de obter informações reais sobre um meio que é altamente heterogêneo e de comportamento dependente do tempo. Contudo, dadas as dificuldades operacionais e de interpretação estas não têm sido empregadas em RSU de maneira freqüente. Uma destas técnicas é o pressiômetro que, apesar de já consagrada, não tem sido usada em RSU a contento, sendo no Brasil inovadora. Considerando esta lacuna, a presente pesquisa engloba todas as fases de construção de um pressiômetro de cravação (Full Displacement) e a sua aplicação na investigação de parâmetros de deformabilidade de resíduos. Um sistema diferenciado de medição de deformações radiais foi projetado para tentar compatibilizar os níveis de deformações necessários e que emprega sensores do tipo Hall. Estes sistemas são colocados ao longo do corpo da sonda em direções ortogonais para avaliar o comportamento da membrana durante a expansão e contabilizar efeitos da heterogeneidade e anisotropia dos RSU. A aplicação do pressiômetro foi realizada no aterro da Muribeca-PE, onde se realizaram ensaios pressiométricos juntamente com sondagens à percussão, ensaios de penetração de cone e análises laboratoriais, cujos resultados foram interpretados com técnicas convencionais fornecendo propriedades mecânicas dos resíduos sólidos. / [en] In order to understand the countless variables governing Municipal Solid Waste (MSW) stress-strain-strength behavior, much has been done in laboratory in the attempt of modeling what in fact happens inside the waste cells, with several levels of successes and failures. However, difficulties in obtaining undeformed samples or in preparing samples that represent real field conditions, given the high rank of heterogeneity in MSW landfills, could be limiting factors. On the other hand, direct field investigation techniques bring along great potential in obtaining in situ real information about an environment that is highly heterogeneous and time dependent. Unfortunately, operational and interpretation difficulties are limiting factors to a more common use of such techniques. One of these techniques is the Pressuremeter, which, despite of being already successfully applied in soils, has not been fairly used in MSW, particularly in Brazil which it has not been tested yet. Considering this gap, this research deals with the construction of a new full displacement pressuremeter and its application in MSW investigations. Unlike the prebored and self-boring techniques, the pressuremeter developed here can be directly pushed in the underground. During its construction and assembly stages a system to measure radial displacements was conceived, which makes use of Hall effect sensor in order to measure higher cavity strains. These systems are mounted along the probes` length in orthogonal directions in order to evaluate the membrane behavior during expansion, therefore accounting heterogeneity and anisotropy in MSW landfills. The application of such pressuremeter was carried out in the Muribeca (PE) landfill, where 16 pressuremeter tests were carried out along with standard penetration test, cone penetrometer tests and laboratory analyses, whose results were interpreted with conventional methodologies providing mechanical waste properties.

No description available.

Continental glaciers covered as much as thirty percent of the present-day inhabited earth during the Quaternary period. Traditionally, one-dimensional consolidation has been considered as the main process of formation for the soils deposited during glaciation. One of the outcomes of accepting one-dimensional consolidation as the main process of formation is that the geomechanical properties of soil in a horizontal plane are isotropic (known as cross-anisotropy). Recent measurements of subglacial pore pressure and preconsolidation pressure profile have indicated that this might not be the case. The role of subglacial shear action has probably been long neglected. The main objective of this research is to investigate the effects of subglacial shearing on the geomechanical properties of glaciated soils. <p> Recent research has found evidence of horizontal property anisotropy associated with the direction of the ice-sheet movement. A testing program was thus proposed to explore the relationship between the anisotropy of property and the direction of past glacier movement. The program involves several fundamental engineering parameters of soils. These parameters together with the corresponding test methods are as follows: (i) Conventional oedometer test yield stress anisotropy; (ii) Oedometer test with lateral stress measurement stiffness anisotropy; (iii) Load cell pressuremeter (LCPM) test in situ stress anisotropy. <p> The physical meaning of yield stress determined by conventional oedometer tests was interpreted as the critical state of structural collapse. The literature review and an experimental study on kaolin samples with a known stress history suggested that yield stress possesses certain dependency on the sampling direction. The anisotropy of yield stress for Battleford till from Birsay, Saskatchewan was also explored by testing directional oedometer samples. In addition, the anisotropy of stiffness was also investigated using a newly developed lateral stress oedometer that is capable of independent measurement of horizontal stresses at three different points with angles of 120 degrees. Preliminary evidence of a correlation between the direction of maximum stiffness in a horizontal plane and the known direction of glacial shear was observed. The correlation between the direction of maximum yield stress and known direction of glaciation was rather poor. Anisotropy of in situ stresses was investigated by conducting LCPM tests in Pot clay in the Netherlands. Based on the LCPM test results, it was concluded that the evidence of a correlation between the anisotropy of in situ stress and known direction of glacial advance is still rather obscure. <p> Although both the laboratory studies and field studies cannot sufficiently confirm the existence of lateral anisotropy of geomechanical properties and its relationship to the direction of the Quaternary ice-sheet movement, the effects of subglacial shearing should not be neglected in assessing the geotechnical properties of glaciated soils. In practice, it is usually found that the preconsolidation pressure profile does not follow the gravitational line as predicted by the one-dimensional consolidation theory and its magnitude is not compatible with the measured effective pressure values at the base of the glacier. It has been suggested that changes in seepage gradient (upward or downward) are responsible for the deviation of preconsolidation pressure profile away from the gravitational line. In this thesis, a new glacial process model consolidation coupled shearing was proposed. This model is based on the framework of traditional soil mechanics (critical state theory, Modified Cam-clay model and one-dimensional consolidation theory) and is consistent with the general geological and glaciological evidences. This model may provide an alternative explanation for the preconsolidation pressure patterns generally observed in practice. It can also be combined with groundwater flow characteristics to explain the diversity of the preconsolidation consolidation patterns. The proposed model was used successfully to obtain the preconsolidation pressure profile observed in Battleford till at Birsay and the subglacial shear-softening phenomenon.