Search results for "Geotechnical engineering"
showing 10 items of 489 documents
Conflicting shear sense indicators in shear zones; the problem of non-ideal sections
1996
Abstract Deflection of pre-existing planar structures such as foliations or veins by ductile shear zones is geometrically very similar to the curvature of newly developed shear zone-restricted foliations in zones that cut a rock with a random fabric. Sense of curvature of shear zone-restricted foliations can be used to determine shear sense, but the deflection of pre-existing planar structures is less reliable. Two examples are presented of shear zones in Australia where both types of structures seem to represent conflicting shear sense. This conflict can be attributed to a geometrical effect which causes deflection of older structures in an opposite direction to shear sense on outcrop surf…
Analytical Approach Determining the Optimal Length of Paired Drip Laterals in Uniformly Sloped Fields
2015
Microirrigation plants, if properly designed, allow for water use efficiency to be optimized and high values of emission uniformity to be obtained in the field. Disposing paired laterals, for which two distribution pipes extend in opposite directions from a common manifold, can contribute to reducing the initial investment cost that represents a limiting factor for small-scale farmers of developing countries where in the last decade, the diffusion of such irrigation systems has been increasing. The objective of this paper is to propose an analytical approach to evaluate the maximum lengths of paired drip laterals for any uniform ground slope, respecting the criteria to maintain emitter flow…
Storm sewer pressurization transient – an experimental investigation
2014
Pipe pressurization is examined experimentally by 144 laboratory experiments in a circular tilting pipe between two tanks, in which the transient was triggered by sudden closing of the downstream tank outlet. The experiments cover ranges of values of slope, velocity and filling ratio of the open-channel flow not explored in previous studies. Situations involving considerable air quantity and consequent intense pressure oscillations were also reproduced. Two different pressurization patterns, defined as “smooth” and “abrupt”, were observed, but only the abrupt pattern produced intense pressure oscillations. The comparison among all the abrupt pressurization surges showed how the oscillations…
Numerical Analysis of Bearing Capacity of a Ring Footing on Geogrid Reinforced Sand
2021
A ring footing is found to be of practical importance in supporting symmetrical constructions for example silos, oil storage container etc. In the present paper, numerical analysis was carried out with explicit code FLAC3D 7.0 to investigate bearing capacity of a ring footing on geogrid reinforced sand. Effects of the ratio n of its inner/outer diameter (Di/D) of a ring footing, an optimum depth to lay the geogrid layer were examined. It was found that an intersection zone was developed in soil under inner-side (aisle) of ring footing, contributing to its bearing capacity. Substantial increase of bearing capacities could be realized if ratio n of a ring footing was around 0.6. Numerical res…
Two-Stage Origin of K-Enrichment in Ultrapotassic Magmatism Simulated by Melting of Experimentally Metasomatized Mantle
2019
The generation of strongly potassic melts in the mantle requires the presence of phlogopite in the melting assemblage, while isotopic and trace element analyses of ultrapotassic rocks frequently indicate the involvement of subducted crustal lithologies in the source. However, phlogopite-free experiments that focus on melting of sedimentary rocks and subsequent hybridization with mantle rocks at pressures of 1&ndash
Comparison of Procedures to estimate Steady Flow Rate in Field Measurement of Saturated Hydraulic Conductivity by the Guelph Permeameter Method
1999
Abstract Different procedures for estimating steady flow rate during field application of the Guelph permeameter method were compared in terms of field-saturated hydraulic conductivity K fs and equilibration time t s estimates. The steady flow rate was evaluated by the slope of the linear portion of the cumulative drop in water level in the permeameter reservoir versus time plot (reference procedure) and by approximate procedures that use the first three or four consecutive values of the rate of fall of the water level equal or differing by less than a given percentage. The influence of the selected time interval between two successive readings ( Δt =2 or 10 min) at the permeameter was also…
Can be GPR technique useful for strength characterization of concrete?
2010
The possibility of material characterization through the GPR measurements, taking into account the integration with the ultrasonic technique, has been studied and possible relationships between the permittivity of materials and their bulk density are discussed. We present here two different approaches. The first one describes an attempt to correlate the mechanical strength of concrete (as well the ultrasonic velocity) with the permittivity of the material. A series of samples of concrete, characterized by different material properties, were used for georadar and ultrasonic measures, seeking correlations among experimental data. The second approach illustrates the comparison between GPR and …
GPR multi-component data analysis
2007
In order to test the capabilities of ground-penetrating radar (GPR) detection, models were reproduced in a laboratory using both plastic and metal cylinders as well as sheets to represent anomalies buried in a plastic tank containing sand. These models, which represent pipes and dipping layers in a homogeneous medium (i.e., sand), were used to detect the object’s position and study its polarization properties based on the different dielectric contrasts between the object and the surrounding medium. We paid particular attention to the choice of medium through which the wavefield propagated, to be sure of its isotropy and homogeneity, in order for the velocity to be the same for every path tr…
Novel instruments and methods to estimate depth-specific thermal properties in borehole heat exchangers
2020
Standard thermal response tests (TRT) are typically carried out to evaluate subsurface thermal parameters for the design and performance evaluation of borehole heat exchangers (BHE). Typical interp ...
Stochastic seismic analysis of hydrodynamic pressure in dam reservoir systems
2002
Hydrodynamic seismic-induced pressure requires careful consideration in the aseismic design of dams. Effects induced by earthquake excitation may cause many-fold increments of hydrostatic pressure. In this study earthquake excitation has been modelled by means of random process theory obtaining the response statistics of a dam-reservoir dynamical system. The analysis has been conducted assuming a rigid retaining wall of the reservoir and dissipative fluid. Copyright © 2002 John Wiley & Sons, Ltd.