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American Society for Testing and Materials

Statistics and Data Analysis in Geology

Discrete particle simulation of particulate systems: A review of major applications and findings


 The spectral ratio between horizontal and vertical components (H/V ratio) of microtremors measured at the ground surface has been used to estimate fundamental periods and amplification factors of a site, although this technique lacks theoretical background. The aim of this article is to formulate the H/V technique in terms of the characteristics of Rayleigh and Love waves, and to contribute to improve the technique. The improvement includes use of not only peaks but also troughs in the H/V ratio for reliable estimation of the period and use of a newly proposed smoothing function for better estimation of the amplification factor. The formulation leads to a simple formula for the amplification factor expressed with the H/V ratio. With microtremor data measured at 546 junior high schools in 23 wards of Tokyo, the improved technique is applied to mapping site periods and amplification factors in the area.

Ground Motion Characteristics Estimated from Spectral Ratio between Horizontal and Verticcl Components of Mietremors.

A review of the recent advances on the treatment of industrial wastewaters by Sulfate Radical-based Advanced Oxidation Processes (SR-AOPs)

The extent of damage and affected areas in Bhuj earthquake (26th January 2001) has provided a unique opportunity to evaluate a wide range of geotechnical issues. A large area in the Rann of Kutch experienced massive liquefaction resulting in ground subsidence and lateral flow. A large number of dams in the Kutch district suffered moderate to severe damages. Many buildings were damaged and collapsed in the city of Ahmedabad situated on the bank of the Sabarmati River. In this paper, the ground response studies at a site in Ahmedabad City along with observations of geotechnical aspects such as ground cracking, sand volcanoes and liquefaction of soils associated with the Bhuj earthquake are discussed. The ground response studies indicate that the varying degree of damage to multistorey buildings in Ahmedabad in the close proximity of Sabarmati river area was essentially due to the collapse and undesirable settlement of partly saturated silty sand deposits. Large settlements are attributed to amplification of the ground and the near resonance condition.

Geotechnical aspects and ground response studies in Bhuj earthquake, India

Northeast India and its adjoining areas are characterized by very high seismic activity. According to the Indian seismic code, the region falls under seismic zone V, which represents the highest seismic-hazard level in the country. This region has experienced a number of great earthquakes, such as the Assam (1950) and Shillong (1897) earthquakes, that caused huge devastation in the entire northeast and adjacent areas by flooding, landslides, liquefaction, and damage to roads and buildings. In this study, an attempt has been made to find the probability of occurrence of a major earthquake (M-w > 6) in this region using an updated earthquake catalog collected from different sources. Thereafter, dividing the catalog into six different seismic regions based on different tectonic features and seismogenic factors, the probability of occurrences was estimated using three models: the lognormal, Weibull, and gamma distributions. We calculated the logarithmic probability of the likelihood function (ln L) for all six regions and the entire northeast for all three stochastic models. A higher value of ln L suggests a better model, and a lower value shows a worse model. The results show different model suits for different seismic zones, but the majority follows lognormal, which is better for forecasting magnitude size. According to the results, Weibull shows the highest conditional probabilities among the three models for small as well as large elapsed time T and time intervals t, whereas the lognormal model shows the lowest and the gamma model shows intermediate probabilities. Only for elapsed time T = 0, the lognormal model shows the highest conditional probabilities among the three models at a smaller time interval (t = 3-15 yrs). The opposite result is observed at larger time intervals (t = 15-25 yrs), which show the highest probabilities for the Weibull model. However, based on this study, the IndoBurma Range and Eastern Himalaya show a high probability of occurrence in the 5 yr period 2012-2017 with >90% probability.

Probabilistic Models for Forecasting Earthquakes in the Northeast Region of India

This paper presents the comprehensive stability analysis of the rock-fill tailing dam constructed at Rampura Agucha zinc mine in Rajasthan, India. The results of the feasibility study carried out prior to the expansion of the dam height from existing 27 to 51 m have been presented. The final cross-section of the tailing dam was arrived based on the extensive stability analysis considering both the upstream and downstream methods of embankment rising. The factor of safety values was calculated from Bishop’s simplified method, Janbu’s method and Spencer’s method by considering the circular failure surfaces. Further, the dynamic stability analyses were also carried out using the pseudostatic approach. The results from the limit equilibrium approaches were validated with the shear strength reduction technique using finite difference-based Fast Lagrangian Analysis of Continua in 2D analysis. The factor of safety values calculated from the different approaches was found to be in good agreement with each other. ...

Stability analysis of rock-fill tailing dam: an Indian case study

There have been significant advances in the application of critical state, CS, in liquefaction potential assessment. This was done by comparing state parameter, ψ with estimated characteristic cyclic stress ratio, CSR due to an earthquake. A cyclic resistance ratio, CRR curve, which can be determined from cyclic liquefaction tests, separates historical liquefied and non-liquefied data points ( ψ , CSR). On the other hand, the concepts of equivalent granular state parameter, ψ *, which was developed for sands with fines, can be used in lieu ψ to provide a unifying framework for characterizing the undrained response of sands with non/low plasticity fines, irrespective of fines content ( f c ). The present work combines these two propositions, and by merely substituting ψ * for ψ into the aforementioned CS approach to capture the influence of f c . A series of static and cyclic triaxial tests were conducted, separately and independently of the concept of ψ *, for sand with up to f c of 30%. The clean sand was collected from Sabarmati river belt at Ahmedabad city in India which was severely affected during the Bhuj earthquake, 2001. The experimental data gave a single relation for CRR and ψ * which was then used to assess liquefaction potential for a SPT based case study, where f c varies along the depth. The prediction matched with the field observation.

Cyclic liquefaction screening of sand with non-plastic fines: Critical state approach

Pile foundations are often subject to lateral loading due to various forces on a variety of structures like high rise buildings, transmission towers, power stations, offshore structures and highway and railway structures. The present investigation is to study the effect of slopes on p-y curves (where p is the static soil reaction and y is the pile deflection) due to static lateral loading in soft clay (Consistency index Ic = 0.42). A series of laboratory model tests were carried out on the instrumented model pile on sloping ground (slopes of 1V:1H, 1V:1.5H, 1V:2H, 1V:3H and 1V:5H) and with varying embedment length to diameter ratio (L/D) of 20, 25 and 30. From the experimental results, the bending moment curves along the pile shaft are double differentiated to obtain the soil resistance (p) and double integrated to obtain the deflection (y) using curve fitting method. New p-y curves for piles located on crest of soft clay with different sloping ground surface under static lateral loading are developed. Moreover, the effect of sloping angles on proposed p-y curves was studied.

T. G. Sitharam

Papers

Geotechnical aspects and ground response studies in Bhuj earthquake, India

Probabilistic Models for Forecasting Earthquakes in the Northeast Region of India

Stability analysis of rock-fill tailing dam: an Indian case study

Cyclic liquefaction screening of sand with non-plastic fines: Critical state approach

Effect of Slope on p - y Curves for Laterally Loaded Piles in Soft Clay