Analytical Study of a Braced Excavation in Weak Clay

Analysis of the problem of braced excavations is complicated by the large number of variables involved and by the complex interaction and behavior of the soil and the supporting materials. For this reason a parametric study was made using the finite-element method of analysis to evaluate the influences of the variables. A rather unique computer modelling technique has been used to accommodate both the large number of variables and the problem of interaction and dissimilar behavior. An example of a computer simulation of a well-instrumented braced cut in Norway is given in sufficient detail to illustrate the applicability of the program.For the parametric study a typical excavation with fully penetrating sheet-pile walls was chosen. Of the parameters concerning soil conditions, the soil deformation modulus was found to have the greatest influence. The relative influence of shear strength, of initial in situ stress, of direction of mobilization of shear stress, and of soil-to-pile adhesion is also shown. All of the parameters concerning support conditions are important but pile stiffness and effective strut stiffness are the most important. The influence of prestressing and strut spacing is also shown.

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Rock Mass Behavior under Tunnel Widening in Asymmetric and Symmetric Modes Considering Different Shapes and Parametric Conditions

Geosciences ◽

10.3390/geosciences9120518 ◽

2019 ◽

Vol 9 (12) ◽

pp. 518

Author(s):

Babar Khan ◽

Syed Muhammad Jamil ◽

Jung Joo Kim ◽

Turab H. Jafri ◽

Jonguk Kim

Keyword(s):

Rock Mass ◽

In Situ Stress ◽

Design Parameters ◽

Tunnel Widening ◽

Tunnel Support ◽

Mass Behavior ◽

Rock Types ◽

The Difference ◽

Support Conditions

To accommodate traffic volume on roads due to ever-increasing population growth, the widening of highways and motorways is in high demand. Nevertheless, the widening of tunnels on these road networks is quite complex due to the presence of numerous rock types, in situ stress, and different widening modes. To overcome these complexities, eight different tunnel shapes were simulated under varying support conditions for asymmetric and symmetric widening. It was found that the tunnels with a round shape, such as horseshoe and semicircular with flatbed, are more effective for asymmetric widening, whereas the provision of a rounded invert in these shapes can reverse the widening option to symmetric. Furthermore, an insignificant effect of the difference in asymmetric and symmetric widening of regular tunnel shapes, such as box, rectangular, and semi-elliptical, was found. A full factorial design statistical analysis confirmed the decrease in tunnel deformation by using various tunnel support systems and showed a significant deformation difference according to monitoring locations at the tunnel periphery. The deformation difference in the case of both tunnel widening modes was also analyzed according to different design parameters. This study provides a comprehensive understanding of rock mass behavior when the widening of any underground opening is carried out.

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The basis for a procedure to specify soil physical properties of a seed bed for wheat

Australian Journal of Agricultural Research ◽

10.1071/ar9790831 ◽

1979 ◽

Vol 30 (5) ◽

pp. 831 ◽

Cited By ~ 13

Author(s):

N Collis-George ◽

JE Lloyd

Keyword(s):

Shear Strength ◽

Physical Properties ◽

Temperature Regime ◽

In Situ Stress ◽

Soil Physical Properties ◽

Soil Conditions ◽

Wide Range ◽

The Mean ◽

Small Increments

The rationale of characterizing seed beds prepared for wheat by describing the environment at a distance from the plant/soil interface by a selected number of measurements on a bulk basis in the horizontal plane at small increments of depth is discussed. A field procedure is described of in situ measurements to specify the soil conditions of biological consequence to germination and emergence. Measurements at small increments of depth are made to determine: (i) moisture status by moisture content and by moisture potential; (ii) aeration status by air-filled porosity; (iii) temperature regime by monitoring the soil temperature profile with depth; (iv) soil strength by the bulk shear strength of the soil under in situ stress conditions. Field results suggest that the described field procedure is suitable for the routine study of soils involving a wide range of moisture contents, of moisture potentials and of structure. The results show that, within the top 15 cm of a prepared seed bed, soil physical properties change markedly with depth. In particular, tenfold increases of bulk shear strength were measured. Results also showed that bulk shear strength could not be predicted from penetrometer readings and that the mean aerial temperature at 1.2 m is not sufficient to define the mean temperature regime of the developing seedling. The field procedure described is recommended for the characterization of seed beds.

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Application of Symbolic Regression in Modeling Soil Deformation Modulus

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.l3686.1081219 ◽

2019 ◽

Vol 8 (12) ◽

pp. 4802-4806

Keyword(s):

Deformation Modulus ◽

Symbolic Regression ◽

Engineering Properties ◽

Soil Deformation ◽

Test Results ◽

Pressuremeter Test ◽

Geotechnical Parameters ◽

Earth Pressures ◽

And Behavior

It is not simple to determine in-situ horizontal stresses even though vertical stresses could be determined directly. Pressuremeter is not given high importance even though it is useful in illustrating various geotechnical parameters effectively. It is important to characterize geomaterials which in turn helps us to understand the properties and behavior of the materials. Symbolic Regression model has been prepared to relate pressuremeter test results with geotechnical engineering properties. Understandingthese properties help geotechnical engineers in design and analyses of foundations, earth pressures, etc.

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