Amplification of seismic accelerations at slope crests

2009 ◽  
Vol 46 (5) ◽  
pp. 585-594 ◽  
Author(s):  
A. J. Brennan ◽  
S. P.G. Madabhushi
Keyword(s):  
Natural Frequency ◽  
Soil Layer ◽  
Ground Surface ◽  
Surface Structures ◽  
Centrifuge Modelling ◽  
Sloping Ground ◽  
Topographic Amplification ◽  
Tensile Forces ◽  
Seismic Accelerations

Earthquake accelerations can cause many problems in sloping ground. One such problem is that accelerations are greatly amplified at the crest of slopes. This topographic amplification can lead to acceleration gradients along the ground surface, which could create tensile forces in long surface structures that extend between areas of different amplifications. This paper uses centrifuge modelling to demonstrate and quantify this as a problem for a particular slope configuration. A special brittle structure has been constructed to undergo damage in the presence of large differential accelerations. The structure is seen to connect the crest to the level ground behind the crest during an earthquake, reducing the amplitude of the crest motion at the expense of structural tension. Topographic amplification is shown to be a clear function of frequency, and is especially serious for loading frequencies above the natural frequency of the soil layer.

Centrifuge study of seismic response of soil-nailed walls supporting a footing on the ground surface

Géotechnique ◽  
2021 ◽  
pp. 1-41
Author(s):  
Mohammad Hassan Baziar ◽  
Alireza Ghadamgahi ◽  
Andrew John Brennan
Keyword(s):  
Ground Surface ◽  
Soil Surface ◽  
Seismic Stability ◽  
Soil Nails ◽  
Model Soil ◽  
Centrifuge Tests ◽  
Axial Tensile ◽  
Tensile Forces ◽  
Surcharge Load ◽  
Seismic Loadings

Seismic design of soil-nailed walls requires demonstrations of tolerable ranges of wall movements, especially when a surcharge load exists near the wall. In this study, the effect of surcharge location on seismically induced wall movements was investigated using four centrifuge tests. The axial tensile forces, developed along the soil nails during the seismic loadings, were also measured during the tests. At 50g centrifugal acceleration, model tests represented a 12-m-high prototype wall reinforced with five rows of soil nails. To apply a surcharge stress of 30 kPa at the specified location relative to the wall for each model test, a rigid footing was placed on the soil surface. The model soil-nailed walls were subjected to three successive earthquake motions. Surprisingly, it was found that the model wall with the footing located behind the soil-nailed region experienced the largest seismic movements, even more than when the footing was directly behind the wall. Further, the tests showed that the lower soil nails played a key role in the wall stability during earthquake shaking, acting as a pivot for the pre-collapse cases tested, whereas the upper soil nails needed to be sufficiently extended to properly contribute to the seismic stability of the wall.

scholarly journals Dynamics and Temperature Simulation in Multi-Axis Milling

2008 ◽  
Vol 43 ◽  
pp. 89-96 ◽  
Author(s):  
Eduard Ungemach ◽  
Tobias Surmann ◽  
Andreas Zabel
Keyword(s):  
Surface Quality ◽  
Matrix Material ◽  
Ground Surface ◽  
Milling Process ◽  
Surface Structures ◽  
Dynamic Effects ◽  
Lightweight Construction ◽  
Surrounding Matrix ◽  
Simulation Systems ◽  
Very High

Lightweight extrusion profiles with reinforcement elements are promising news in the domain of lightweight construction. The machining of them suffers from several problems: Aside from the question of choosing a suitable tool, feed rate, and milling strategy, an excessive rise in temperature could lead to stress and even a distortion due to the differing thermal expansion of the reinforcement material and the surrounding matrix material. A simulation of the milling process could, in addition to force and collision calculations, recognize this case before manufacturing. For certain milling applications like seal surfaces, a certain roughness of the manufactured surface is necessary. In many other cases, a smooth surface of very high quality is desirable. Available simulation systems usually completely lack the simulation of dynamic effects, which have a great effect on the final surface quality, and therefore are not able to predict the resulting surface quality. In this paper simulation methods are presented that are capable of simulating the dynamic behavior of the tool in the milling process and the resulting flank and ground surface structures. Additionally, a fast temperature simulation for heterogeneous workpieces with reinforcement elements, which is based on the finite difference method and cellular automata, is introduced.

Research on the Vibration Attenuation Rules and Wave Propagation Law under Impacting Drill on the Deep Soil Layer

2011 ◽  
Vol 250-253 ◽  
pp. 1971-1977
Author(s):  
Bo Zhang ◽  
Lian Jin Tao ◽  
Wen Pei Wang ◽  
Ji Dong Li
Keyword(s):  
Wave Propagation ◽  
Soil Layer ◽  
Ground Surface ◽  
Ground Vibration ◽  
Vibration Source ◽  
Vertical Acceleration ◽  
Deep Soil ◽  
Deep Soil Layer ◽  
Propagation Law ◽  
Vibration Attenuation

A field test is carried out to study the effect of vibration while treating foundation using vibroflotation method in the deep soil layer in Zhengzhou, China. The vibration attenuation rules and wave propagation rules in different formations caused by different numbers of drills are analyzed. Evaluate the influence on the adjacent buildings. The result shows that the vibration will be generated in foundation obviously in the process of construction using the method. Vibration force, impact frequency and site soil are important influence factors on ground vibration attenuation. The analysis reveals that the maximum vertical acceleration attenuation velocity was much greater in near area than that in the relative far area. The waves caused by vibration propagate in two ways: (1) surface wave is generated on the wall of drill hole and propagated to the ground surface, and attenuated in a certain distance (<8m); (2) shear wave was generated and propagated in the impacting formation and attenuated from the deep formation to the ground surface. Vibration amplitude is mainly distributed in the low frequency range in the areas which far away from vibration source and in the silt layer near the ground surface.

scholarly journals Full-depth avalanche occurrences caused by snow gliding, Coquihalla, British Columbia, Canada

1999 ◽  
Vol 45 (151) ◽  
pp. 539-546 ◽  
Author(s):  
Jennifer Clarke ◽  
David McClung
Keyword(s):  
British Columbia ◽  
Stainless Steel ◽  
Ground Surface ◽  
Free Water ◽  
Important Influence ◽  
Reliable Indicator ◽  
Climate Data ◽  
Cascade Mountains ◽  
Sloping Ground ◽  
Snow Gliding

AbstractSnow glide is the translational slip of the entire snowpack over a sloping ground surface, and it is thought that rapid rates of snow glide precede full-depth avalanches. The nature of avalanches that release at the ground makes them difficult to predict and difficult to control using explosives.On-slope instrumentation comprised of stainless-steel "glide shoes" was used to measure rates of snow glide for two winters on a bedrock slope adjacent to the Coquihalla Highway, Cascade Mountains, British Columbia, Canada. Climate data and avalanche occurrences were recorded by the British Columbia Ministry of Transportation and Highways.Our results show that the supply of free water to the snow/ground interface by rain or snowmelt is the most important influence on full-depth avalanche release. Full-depth avalanche release responds to rainfall and snowmelt events within 12-24 hours. Occasionally, full-depth avalanches occur unexpectedly during clear, cold periods. Snowmelt by radiation is thought to contribute enough meltwater during these cold periods to induce higher rates of snow glide and full-depth avalanche release. The results also indicate that snow glide alone is not a reliable indicator for full-depth avalanche release.

scholarly journals Estimating Soil Moisture Distributions across Small Farm Fields with ALOS/PALSAR

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yuki Kojima ◽  
Kazuo Oki ◽  
Kosuke Noborio ◽  
Masaru Mizoguchi
Keyword(s):  
Soil Moisture ◽  
Soil Layer ◽  
Ground Surface ◽  
Time Domain Reflectometry ◽  
Moisture Distribution ◽  
Small Scale ◽  
Alos Palsar ◽  
Coverage Ratio ◽  
Fine Resolution ◽  
Soil Moisture Distribution

The ALOS (advanced land observing satellite) has an active microwave sensor, PALSAR (phased array L-band synthetic aperture radar), which has a fine resolution of 6.5 m. Because of the fine resolution, PALSAR provides the possibility of estimating soil moisture distributions in small farmlands. Making such small-scale estimates has not been available with traditional satellite remote sensing techniques. In this study, the relationship between microwave backscattering coefficient (σ) measured with PALSAR and ground-based soil moisture was determined to investigate the performance of PALSAR for estimating soil moisture distribution in a small-scale farmland. On the ground at a cabbage field in Japan in 2008, the soil moisture distribution of multiple soil layers was measured using time domain reflectometry when the ALOS flew over the field. Soil moisture in the 0–20 cm soil layer showed the largest correlation coefficient with σ (r=0.403). The σ values also showed a strong correlation with the ground surface coverage ratio by cabbage plants. Our results suggested that PALSAR could estimate soil moisture distribution of the 0–20 cm soil layer across a bare field and a crop coverage ratio when crops were planted.

Three-dimensional numerical modelling of discrete piles used to stabilize landslides

2011 ◽  
Vol 48 (9) ◽  
pp. 1393-1411 ◽  
Author(s):  
S. Kanagasabai ◽  
J. A. Smethurst ◽  
W. Powrie
Keyword(s):  
Slip Plane ◽  
Numerical Models ◽  
Three Dimensional ◽  
Ground Surface ◽  
Lateral Force ◽  
Plane Interface ◽  
Single Pile ◽  
Sloping Ground ◽  
Stabilizing Piles ◽  
Rigid Pile

Three-dimensional finite difference analyses have been carried out to investigate the behaviour of a single pile used to stabilize a slipping mass of soil by embedment into a stable stratum. Analyses were initially carried out to determine the reduction in the limiting pile–soil lateral force per metre length, pu, close to the unconfined ground surface. The analyses then explore the failure mechanisms for landslide stabilizing piles categorized by Viggiani. The effects of varying the strength of the slip plane interface between the sliding and stable strata, and of a sloping ground surface on the behaviour of the pile are then investigated. The results from numerical models with a rigid pile, a distinct plane of sliding, and a horizontal ground surface, as assumed by Viggiani, agree well with his theoretical mechanisms. Lower values of pu close to the ground surface and adjacent to the sliding plane are found to reduce the maximum shear resistance that piles can provide to the slipping mass when compared with Viggiani’s theoretical solutions. Further analyses show that the strength of the slip plane interface has a considerable influence on pile behaviour, and that the slope of the ground surface is only significant above a certain angle.

scholarly journals Development of a Land Surface Model Including Evaporation and Adsorption Processes in the Soil for the Land–Air Exchange in Arid Regions

2007 ◽  
Vol 8 (6) ◽  
pp. 1307-1324 ◽  
Author(s):  
Genki Katata ◽  
Haruyasu Nagai ◽  
Hiromasa Ueda ◽  
Nurit Agam ◽  
Pedro R. Berliner
Keyword(s):  
Water Vapor ◽  
Soil Water ◽  
Land Surface ◽  
Soil Layer ◽  
Land Surface Model ◽  
Ground Surface ◽  
Surface Model ◽  
Water Vapor Flux ◽  
Vapor Flux ◽  
Adsorption Processes

Abstract A one-dimensional soil model has been developed to better predict heat and water exchanges in arid and semiarid regions. New schemes to calculate evaporation and adsorption in the soil were incorporated in the model. High performance of the model was confirmed by comparison of predicted surface fluxes, soil temperature, and volumetric soil water content with those measured in the Negev Desert, Israel. Evaporation and adsorption processes in the soil have a large impact on the heat and water exchange between the atmosphere and land surface and are necessary to accurately predict them. Numerical experiments concerning the drying process of soil are performed using the presented model and a commonly used land surface model. The results indicated that, when the dry soil layer (DSL) develops, water vapor flux to the atmosphere is caused by evaporation in the soil rather than evaporation at the ground surface. Moreover, the adsorption process has some impact on the water and heat balance at the ground surface. The upward water vapor flux during the daytime is due to evaporation of soil water in the DSL, which is stored during the night due to adsorption. When the DSL progresses sufficiently, almost the same amounts of water are exchanged between the air and the soil surface by daytime evaporation and nighttime adsorption. In such conditions, latent heat due to evaporation and adsorption in the soil also work to reduce the diurnal variation of surface temperature.

Effects of Slope Grade on Soil-Pipe Interaction: Full-Scale Experiments

2020 ◽  
Author(s):  
Mohammad Katebi ◽  
Dharma Wijewickreme ◽  
Pooneh Maghoul ◽  
Kshama Roy
Keyword(s):  
Practice Guidelines ◽  
Ground Surface ◽  
Full Scale ◽  
Mountainous Areas ◽  
Buried Pipelines ◽  
Sloping Ground ◽  
Physical Model Tests ◽  
Industry Practice ◽  
Surface Inclination ◽  
Soil Pipe

Abstract In the current industry practice guidelines, the soil restraints to assess the behaviour of pipelines subject to permanent ground displacements are numerically characterized using independent “soil springs”. These guidelines have been primarily generated by considering the typical configurations of buried pipelines in level ground. The assumption of level ground does not always hold true when assessing pipelines located on sloping ground in mountainous areas and riverbanks. This research presents the outcomes from a set of full-scale physical model tests conducted on a pipe buried in slopes. The results highlight the significance of the slope grade effects on soil-pipe interaction. The results are useful as input to modify soil springs accounting for the ground surface inclination.

Three Dimensional Numerical Analysis of Ground Settlement Induced by Shield Tunneling

2012 ◽  
Vol 182-183 ◽  
pp. 937-940
Author(s):  
Zhong Chang Wang
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Maximum Settlement

The fine numerical simulation is used to study the ground settlement of complex stratum owing to shield construction by ANSYS program. It is shown that the closer the distance between soil layer and the axis of tunnel is, the smaller the disturbance of construction is, the obvious the ground surface settlement is. The value of the maximum settlement at the center of the surface is 7.4mm. The maximum settlement of vault is 14mm. The ground subsidence in cross section distribution is shaped of normal distribution. The closer the distance between soil layer and ground surface is, the smaller the vertical displacement is, the bigger the width of settlement trough of soil layers is. The width of settlement trough is 25m. The volume loss rate of shield tunnel is about 0.32%. The width coefficient of ground settlement trough is 0.56. The tendency of ground settlement decrease to become gentle with the advance of shield construction. The ground settlement keeps constant after tunnel face advancing to 30m.

scholarly journals Growth and development of soybean roots according to planting management systems and irrigation in lowland areas

2016 ◽  
Vol 46 (9) ◽  
pp. 1572-1578 ◽  
Author(s):  
Gerson Meneghetti Sarzi Sartori ◽  
Enio Marchesan ◽  
Ricardo De David ◽  
Fernando Teixeira Nicoloso ◽  
Márcio Renan Weber Schorr ◽  
...  
Keyword(s):  
Growth And Development ◽  
Block Design ◽  
Soil Layer ◽  
Ground Surface ◽  
Field Capacity ◽  
Development Stage ◽  
Management Systems ◽  
Lower Growth ◽  
Deep Tillage ◽  
Soybean Roots

ABSTRACT: The presence of a compacted soil layer near the ground surface in paddy fields may limit the growth and development of soybean roots. The objective of this study was to evaluate different planting management systems and irrigation on growth and development of soybean root systems in lowland area. The experiment was carried out in 2013/14 and 2014/15 crop seasons in randomized complete block design with factorial treatment (3x2), with four replications. The treatments consisted of different planting management systems: sowing with double disc (A1); sowing with shank (A2) and deep tillage + sowing with double disc (A3), and irrigation: irrigated (D1) and non irrigated (D2). Planting management systems and irrigation influenced the growth of soybean roots. When double disc was used, roots have lower growth and increase in diameter. Use of shanks and deep tillage provide increased growth and development of soybean roots and greater depth distribution. An additional 55mm of irrigation during the V4 soybean development stage provides increased surface area and root volume in when the soil moisture reaches values below 60% of field capacity.

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