The exact distributions of gravity stresses are obtained within slopes of finite height inclined at various angles, −β (β = π/2, π/3, π/4, π/6, and π/8), to the horizontal. The solutions are obtained by application of the theory of a complex variable. In homogeneous, isotropic, and linearly elastic slopes under plane strain conditions, the gravity stresses are independent of Young's modulus and are a function of (a) the coordinates, (b) the height, (c) the inclination angle, (d) Poisson's ratio or the coefficient of earth pressure at rest, and (e) the volumetric weight. Conformal applications that transform the planes of the various slopes studied onto the upper half-plane are analytically obtained. These solutions are also represented graphically.
In recent years radioisotopes have been increasingly used for determining site values of the density and the water content of soils. Since field measurements obtained by neutron moisture gauges are relative, these instruments must be calibrated. Calibration is usually carried out in the laboratory by plotting neutron counting rates versus known water content values of several soil media, homogeneous as well as heterogeneous.
The accuracy of the factory calibration curve of a widely used, commercial neutron depth moisture gauge was evaluated both in the field and in the laboratory by comparing probe readings to measured volumetric water contents of several soil mixtures. The analyses of the laboratory results indicate that the factory linear calibration curve is satisfactory for volumetric water contents not exceeding 40%. However, for volumetric water contents in the range from 40 to 100%, the relationship between probe readings and volumetric water contents is nonlinear. This nonlinear curve was found to be quite different from that obtained in the field calibration campaign carried out in a deposit of sensitive Champlain clay having volumetric water contents which compare well with those of the laboratory-prepared clay mixtures.
This technical note describes the analysis of the strain field around a simple pile. The analytical solution is obtained by using a spherical coordinate system of reference. It is shown that the expressions for the various strains are very simple. Streaming motions and octahedral shear strain contours are presented in graphical forms. Key words : simple pile, streaming motion, strain field.
NOTES 369 would lead t o a n increase in the apparent cohesion in the soil mass. However, this observation cannot be directly extrapolated t o larger tunnels because of scale effects. In fact, as the dimensions increase, the volumetric forces such as seepage forces increase more quickly than the surface forces, such as the cohesion.
ConclusionThis study has led t o a precise description of the impact of an experimental microtunnel on the surrounding hydraulic conditions and has also provided valuable information o n the stability of the construction.The three-dimensional finite element analysis shows that the hydraulic head losses are concentrated close t o the tunnel face and are in agreement with field measurements of the piezometric levels. As a consequence, the generated water seepage forces increase the supporting pressure required t o ensure face stability. This was shown both by the twodimensional numerical equilibrium analysis and by the experimental measurements.These results, which cannot be directly extended t o a larger tunnel because of the scale effect, show that it is possible to quantify the effect of water seepage forces o n the tunnel face stability. The future development of numerical methods should encourage designers t o use them for better prediction of the required supporking pressure, leading t o safer design of underground constructions.
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