Ground Depth Research Articles

Construction of large cross-section double-tier Metropolitan Inter-city Highway (Ken-O-Do) Ome Tunnel by NATM

Ome Tunnel is a double-tier highway tunnel with large cross-section of 220–260 m 2 excavated at a shallow depth in unconsolidated ground. The tunnel was excavated by NATM. Since the tunnel passes under a road in dense residential area, surface settlement due to tunneling was restricted. Therefore, various auxiliary construction method such as long span steel pipe fore-piling with injection was adopted based on monitoring and analyzing ground behavior during construction. A total of 1060 m of tunneling work was successfully completed without major interruption of work excessive damage on surface residents and other facilities.

The analysis of methods for measurement of methane oxidation in landfills

Landfills and dumps are important sources of atmospheric methane. There is no generally accepted estimate of the influence of methane oxidation on landfill methane emissions. The present work aimed to analyse different methods for the investigation of methane emission and oxidation in methane-producing environments (wetlands, landfills, sludge checks), and to develop the precise procedure for the landfills. The combination of geochemical and microbiological methods to estimate and monitor the oxidation and emission of methane in landfills during different seasons is proposed. It includes the measurements, both on the surface and at different depths (up to 1 m) of landfill ground of the following parameters: (1) concentrations of methane, carbon dioxide and oxygen; (2) quantity of 13C isotope in gas samples; (3) methane-oxidation activity of landfill grounds assayed with two different methods: (a) in conditions of no moisture or substrate limitations, and (b) in conditions with a minimal deviation to in situ conditions; (4) the density of methanotrophic microbial population.

Regional‐scale modeling of soil freeze/thaw over the Arctic drainage basin

The freezing and thawing of the active layer of soil in the Arctic terrestrial drainage basin is simulated using a one‐dimensional heat conduction model. Main forcing data are surface air temperature and snow thickness. Emphasis is placed on producing a topography‐improved temperature data set from National Centers for Environmental Prediction (NCEP) reanalysis data, and a snow height data set compiled from SSM/I satellite data and observed climatological snow density. Soil bulk density, soil type and its relative composition are derived from the SoilData System of the IGBP‐DIS. The model is run with 25 km × 25 km resolution and daily time steps for the period September 1998 through December 2000. We compare modeled thaw depths and active layer depths with those measured at Circumpolar Active Layer Monitoring (CALM) field sites. This study shows for the first time the highly variable daily thaw depth over permafrost and seasonally frozen ground depth in nonpermafrost areas, as well as freezing and thawing periods for the whole pan‐Arctic landmass.

Pressure-based in-process measurement by the null method for automatic compensation of wheel wear during surface grinding

This paper deals with automatic compensation of grinding wheel wear in wet grinding by pressure-based in-process measurement. A pressure sensor is set close to a grinding wheel with a small gap. When grinding fluid is dragged into the gap by the rotation, the wear of the grinding wheel can be predicted by using hydrodynamic pressure that has been generated, which corresponds to the gap thickness and topography of the surface. This method was applied to a numerically controlled surface grinding machine. Some characteristics of the pressure were measured. The pressure sensor was repositioned to keep the pressure constant with the null method. The spindle was also repositioned according to the sensor displacement, which was equal to the worn thickness of the grinding wheel. The error of the ground depth with compensation was less than the feeding step for the compensation. The measurement performance by the null method was compared with that obtained without compensation, with compensation by a deflection method and by the contact method.

A Classification of Subantarctic Heard Island Vegetation

The vascular and bryophyte floras of subantarctic Heard Island were classified using cluster analysis into six vegetation communities: Open Cushion Carpet, Mossy Feldmark, Wet Mixed Herbfield, Coastal Biotic Vegetation, Saltspray Vegetation, and Closed Cushion Carpet. Multidimensional scaling indicated that the vegetation communities were not well delineated but were continua. Discriminant analysis and a classification tree identified altitude, wind, peat depth, bryophyte cover and extent of bare ground, and particle size as discriminating variables. The combination of small area, glaciation, and harsh climate has resulted in reduced vegetation variety in comparison to those subantarctic islands north of the Antarctic Polar Front Zone. Some of the functional groups and vegetation communities found on warmer subantarctic islands are not present on Heard Island, notably ferns and sedges and fernbrakes and extensive mires, respectively.

Measurements of temperature distribution in ground

Temperature distributions in ground are important, for example, for calculations of heat losses of buildings to the ground, for design of thermal energy storage equipment and ground heat exchangers, and for analysis of biodegradation processes of organic substances and processes of nitrification. In this communication, the temperature distributions measured in ground since the summer of 1999 to the spring 2001 are presented. The investigation has been done in Poznan for two different ground surface covered locations (car park and lawn). Temperatures were measured with thermocouples distributed in ground at a depth from 0 to 7 m (car park) and from 0 to 17 m (lawn). It was found that the short-period temperature variations reached a depth of approximately 1 m. From July to the end of September from the surface region at ground depth (below about 1.5 m) a heat flux of density q=3.6W/m2 was transferred. The measurements show also that during the summer period the temperature of ground under the bare surface (car park) below 1 m was about 4° higher in comparison with the temperature of ground covered with short grass (lawn). However, in winter, the temperature distributions were almost the same. A comparison of the Buggs's formula for the ground temperature distribution adopted to the European region of the Poznan city shows a good agreement with the experimental data.

Illusory three-dimensional rotation of horizontal lines: a new motion-depth illusion.

A new motion--depth illusion is reported. When a curved aperture translates vertically and stationary horizontal lines can be seen through it, the line lengths on the retina change continuously because of the occlusion. Instead of seeing the aperture translate, subjects sometimes see the lines rotate in depth around a vertical axis. This is a rare kind of illusion: an ambiguous motion which can be seen as either stationary in two dimensions or rotating in three dimensions. Three-dimensional rotation was more often observed when the luminance difference between the horizontal lines and the background was larger than that between the aperture and the background. This illusion demonstrates that motion detection and the structure-from-motion process correlate with figure--ground segregation, depth stratification, and figural-completion processes based on luminance contrast.

Monitoring ground‐temperature conditions in central Sakha

Three Russian researchers report the results of 15 years of monitoring ground temperatures in central Sakha, with the objective of detecting patterns of change in permafrost conditions associated with global warming. Considerable attention is devoted to recording year‐to‐year variability in ground temperature and depths of seasonal thawing and correlating these with terrain and substrate type, type of vegetation cover, and interannual changes in meteorological conditions.

Effects of pre-rolling and metal removal on the fatigue life of lubricated rolling/sliding contact

In this experiment, after the test specimens are preloaded at different first-step rolling cycles, the surface layer of the lower speed roller is ground to different depths by a grinder along the radial direction. With a new higher speed roller, the effects of the ground depth and first-step rolling cycle on the fatigue life of lubricated rolling/sliding contact are investigated using a 0.45% carbon steel pair. Results show that the prerolling cycles with metal removal can improve the rolling fatigue life. It is found that when the surface hardness of the specimen starts to approximate the saturated value at the first-step rolling cycle with the ground depth to the position of its maximum hardness, the rolling fatigue life with this preloading operation is 3.3 times that with the normal operation for the second-step load of 588 N. This increment in the rolling fatigue life can be reasonably explained by the measured plastic flow of the surface layer and the theoretical results of the residual stress below the contact surface.

Evaluation of Seismic Settlement Potential of Saturated Sandy Ground Based On Concept of Relative Compression

ABSTRACT Mechanisms regarding the earthquake-induced settlements of saturated sandy deposits with level or nearly level ground surface are revealed based on new post-earthquake stress-strain constitutive analysis and experimental evidence. It was found that: 1) the residual volumetric strain of saturated sand evr induced by drained consolidation following cyclic undrained loading, depends on an irreversible dilatancy component evd.ir and a residual shear strain during the consolidation γr only; 2) change in evd.ir can universally be measured using an index “relative compression, Rc” for different sands over a wide range of density; and 3) a consistantly good correlation exists between Rc and maximum double amplitude shear strain induced by preceding cyclic undrained loading. From these theoretical and experimental findings, new analytical and empirical methods with a high degree of physical rationale were developed for predicting earthquake-induced maximum undrained shear strain and the resulting residual volumetric strains. As a consequence, the seismic ground surface settlement potential for level sandy deposits can be evaluated only by integrating the relative compression along ground depth. The proposed methods were confirmed to be effective by comparing the predictions with observations made during the 1995 Hyogoken-Nambu earthquake.

Impact of Clipping on Root Systems of 3 Grasses Species in Tunisia

The study concerns the impact of herbivory on the root systems of 3 perennial grasses, buffelgrass (Cenchrus ciliaris), digitgrass (Digitaria commutata) and needlegrass (Stipa lagascae), growing in the arid zones of Tunisia. The study simulated animals feeding of the grasses by affecting cuttings at various times throughout the spring growing period. The following effects on the root systems of the grasses were observed. When there is continual overgazing (simulated by cutting all sprouts down the ground level along the spring), more than 65% of the roots off all 3 species are found in the salty upper 15 cm of soil. In case of medium average grazing (simulated by 2 to 3 cuttings), the root system again remains superficial for buffelgrass (C. ciliaris), with 58 to 67% of the roots located in the upper 15 cm of soil. Digitgrass (Digitaria commutata) and needlegrass (Stipa lagascae), however, develop deeper roots with 68 to 86% in the upper 30 cm of soil. When grazing is light (just one cutting), all 3 species perform all most exactly as if there had been no grazing compared to (a control plot) with 85% of the root system located in the upper 50 cm and about 15% at 50 to 75 cm of ground depth. On the basis of this experiments, it is suggested that grazing on these grasses should be allowed just once each spring, thereby allowing: 1- To take advantage of the aboveground contained in these grasses in spring. 2- Preservation of a deep root system which will thereby have a much better chance of getting through the water stress summer season.

Bait loss from bottom-set longlines as determined by underwater observations and comparative fishing trials

Losses of herring, capelin and squid baits from bottom-set longlines for cod ( Gadus morhua) were compared using underwater observation techniques and comparative fishing methods. Underwater observations revealed that squid was better at staying on hooks than herring and capelin. The percentage of bait lost after a given soaking time and the duration a piece of bait remained on a hook at a given intensity of attack by fish were used as criteria to estimate bait tenacity. Capelin bait was lost more readily (44%) than squid (20%, P < 0.1), but herring was lost more significantly (75%) than either squid ( P < 0.001) or capelin bait ( P < 0.05). At the same intensity of attack, squid tended to stay on the hook for longer than herring or capelin. Comparative fishing trails revealed that the rate of bait loss was related to fishing ground depth, bait type and mainline type. More bait was lost in deeper waters for both squid and herring bait and on both floating polypropylene (PP) and sinking polyester (PES) mainlines. For both bait types, significantly more bait was lost in sinking PES mainlines set on the bottom than floating PP mainline set off the bottom ( P < 0.01). For both mainline types (PP and PES), significantly more herring bait was lost than squid bait ( P < 0.01).

The effect of water seepage forces on the face stability of an experimental microtunnel

The face heading stability of underground constructions remains quite difficult to assess, especially when groundwater is present. To investigate this, an experimental microtunnel was excavated at shallow depth in soft ground, below the water table. In agreement with field measurements of the piezometric level changes, a three-dimensional finite element analysis of groundwater flow shows that the head losses are concentrated in the close vicinity of the tunnel face. Both numerical equilibrium analysis and field measurements were used to show that the resulting seepage forces substantially increase the supporting pressure required to ensure face stability. Key words : microtunnel, shallow depth, soft ground, seepage forces, face stability, supporting pressure.

A parametric study on some aspects of ground-borne vibrations due to rail traffic

The results of a parametric study on a three-dimensional model of ground-borne vibrations due to rail traffic are presented. Addressed in this study are the effects of train speed, train distance and ground depth. Several conclusions are drawn regarding the significance of each of these factors.

Case history: Seismic exploration in Egypt’s Eastern Desert

Although oil exploration has been performed in the Eastern Desert of Egypt for over a century, seismic reflection techniques have only been in use for less than a fourth of that time. In an effort to improve seismic imaging of geologic targets, many styles of acquisition and processing have been tested, accepted, or discarded. Over the last twenty‐four years, seismic data acquisition has evolved from low‐channel analog to high‐channel digital recordings. The most difficult exploration problems encountered in these efforts have been the low‐frequency and high‐energy ground roll and depth of penetration when imaging the oil producing Pre‐Miocene sandy reservoirs below the highly reflective salt and evaporites. Efforts have been focused on developing seismic processing procedures to enhance the seismic data quality of recently acquired seismic data and developing new acquisition methods to improve seismic data through acquisition and processing. In older acquisition, the new processing has improved the seismic quality (vertical and lateral resolution), but it still retains a low‐frequency character. In the newly acquired seismic data, however, there is improved reflection continuity, depth of penetration, and resolution. We attribute this result to the change from low‐fold (6–24 fold), long receiver and source patterns (50 to 222 m) to high fold (96 fold) short receiver and source group (25 m), and spectral balancing in the processing. The most recent acquisition and processing have greatly improved the quality of the shallow seismic reflections and the deeper reflections that have helped unravel the structural and stratigraphic style of the deeper portions of the basin.

Magnetic Fluid Grinding for Innersurface of Pipe of Which Cross-sectional Shape is Hexagonal Circle.

In magetic fluid grinding for innersurface of pipe of which cross-sectional shape was hexagonal circle, a ratio of ground area to whole innersurface area of pipe and distribution of ground depth were studied experimentally and theoretically. Whole innersurface of pipe was ground under revolution speed of 125 rpm. But, over its speed, ground area decreased with the increase of revolution speed. The distribution of ground depth in innersurface of pipe wad changed by the change of revolution speed. Such both properties were explained by the change of grinding load which was the sum of magnetic buoyant force Fm of a float, a force Fs due to squeeze effect and a force Fd due to viscous damping effect. Therefore, if optimum grinding load was designed, the whole innersurface of pipe of which cross-sectional shape was hexagonal circle is ground sufficiently.

Radiocesium contamination in soil due to the Chernobyl accident

Three different cereal cultivated fields (rice, maize/wheat, wheat/barley) were selected and soil samples were collected in order to study the behaviour of the radiocesium deposited over the crops after the Chernobyl accident fall-out (April 1986) together with its distribution at different ground depths. For each field, soil samples were removed during the sowing (Oct–Nov '86), in Spring (Apr '87) and during the harvest time (Jun–Sept '87). The40K concentration and stable potassium content in soil was also evaluated by nuclear spectrometry and by atomic absorption spectrometry. Beside soil sample measurements, the cultivated cereals produced in the 1986 harvest (rice, maize, wheat) were analyzed to evaluate the deposited contamination, and in order to evaluate the contamination during the growth and naturation we also analyzed whole plants (roots, stalks, grains) of the cultivated cereals (rice, wheat, barley) in 1987. Results are presented and discussed.

年平均気温から地盤の最大凍結・融解深度を推定する方法

A method is described for the prediction of maximum freeze/thaw penetration depth in snow-and vegetation-free ground as a function of the mean annual air temperature. Annual variation in ground surface temperature was fitted by a sinusoidal curve with the amplitude, Tos. The meteorological data show that the value of Tos ranges from 11° to 16°C in Japan. Three sinusoidal curves with the Tos values of 11°, 13° and 15°C were used for the calculation of the freeze/thaw depth. The Aldrich equation allowed the calculation to be made. The freezing and thawing indices involved in this equation were determined for every degree of the mean annual ground surface temperature. The maximum freeze/thaw depth was calculated for four kinds of ground materials, i.e., volcanic ash, sand/silt, gravel and rock, and then plotted against the mean annual surface temperature. The diagram indicates that the freeze/thaw depth increases as mean annual surface temperature approaches 0°C and with rising both thermal conductivity and volumetric water content of the ground material. The relationship between the mean annual air temperature and the maximum freeze/thaw depth was obtained using the empirical relation between the mean ground surface and air temperatures. The predicted depths agreed fairly well with the measured depths in various cold environments where the mean annual air temperature is known.

Obsidian Hydration Dating: The Effects of Mean Exponential Ground Temperature and Depth of Artifact Recovery

Obsidian Hydration Dating: The Effects of Mean Exponential Ground Temperature and Depth of Artifact Recovery

Human impact on tundra environment at the Ny-�lesund Station, Svalbard

Studies were performed in Ny-Alesund, Spitsbergen, in June and July 1986 in order to gain an insight into the effect of activities of the polar research station on the nearby environment. It was found that chemical and mechanical factors were the most detrimental to the tundra environment. Fuel oil spills (110 m3 in 1986), which spread via surface and ground waters, were the most damaging of the chemical factors. Domestic sewage polluted the waters of Kolhamna Bay within an area of only 0.5 ha around its outlet in the sea. Vehicles and trampling caused mechanical damage inducing destruction of plant cover and changes in the ground structure; it modified ground moisture, bulk density and depth to the permafrost. The area degraded by human activity in the vicinity of the Ny-Alesund Research Station comprised 45 ha. The human impact around the polar station could be lessened by providing an alarm system to detect leaks and safety embankments around the oil tanks and pipelines, utilizing a settling tank for sewage, providing a simple incinerator for solid wastes, and instructing the inhabitants how to minimise impact on the environment.