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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)

A resonant column apparatus can provide the wave velocities of geomaterials under torsional and flexural vibrations for a range of strain levels, within the elastic limit. The testing specimen is vibrated in its fundamental mode and the frequency that produces maximum strains in the sample is picked up as the resonant frequency. The wave velocities are obtained from the resonant frequencies and elastic moduli of the material can be calculated from the wave velocities. The paper presents the numerical simulation of the resonant column tests on jointed rocks by employing a distinct element method (DEM). The resonant frequency has been evaluated by monitoring the displacements at the edges of the sample during vibrations. Resonant frequencies of the testing jointed samples under long wavelength condition have been obtained under various strain levels and have been compared against that obtained from laboratory experiments. When the wavelength of propagating wave is much longer than the joint spacing, it is known as a long wavelength condition. The long wavelength propagation of waves is a general condition in earthquake engineering. The transmission of vibrations across joints has also been shown for the samples with multiple parallel joints.

Numerical Simulation of Resonant Column Tests on Jointed Rocks Using DEM

This chapter is an extension study of the previous chapter which is also categorized under air-blast loading. In the previous chapter, the air-blast effects were investigated on the sand deposits which were located at ground zero locations. This chapter deals with underground structures like pipelines and investigates the effect of air-blast loading on them. The overburden sand above the pipeline acts as sacrificial layers and attenuates the effect of blast wave before reaching the buried structures. A shock tube-based facility has been proposed to study the effects of air-blast on embedded structures like buried pipelines. Dimensional analysis procedure used to predict the real-scale damage is outlined. In addition, a numerical simulation of the air-blast impact on the buried pipeline is presented, which is also used to validate the results from prototype laboratory model tests using scaling laws.

Response of Embedded Structures in Granular Material to Air-Blast Wave Loading

In the present paper, the constitutive model is proposed for cemented soils, in which the cementation component and frictional component are treated separately and then added together to get overall response. The modified Cam clay is used to predict the frictional resistance and an elasto-plastic strain softening model is proposed for the cementation component. The rectangular isotropic yield curve proposed by Vatsala (1995) for the bond component has been modified in order to account for the anisotropy generally observed in the case of natural soft cemented soils. In this paper, the model proposed is used to predict the experimental results of extension tests on the soft cemented soils whereas compression test results are presented elsewhere. The model predictions compare quite satisfactorily with the observed response. A few input parameters are required which are well defined and easily determinable and the model uses associated flow rule.

Prediction of extension test results of soft cemented clays with a simple constitutive model

In India, presently 320 million people remain in the water-starved parts of the country, and according to the United Nations, 840 million people are expected to be water-starved in India by 2050. Although there has been no significant change in India's rainfall pattern, the number of areas under drought in India is increasing every year. Increase in population is one of the reasons for water scarcity, but inefficient management of the precipitation received stands as the major cause. Although extreme rainfall events are significantly increasing, there is a spatial nonuniformity in the rainfall events that occur. This makes it difficult to preplan large-scale water storage at different locations. Solution to India's water problem lies in conserving the abundant monsoon water bounty by storing it in coastal reservoirs for future use. This paper focuses on the challenges and opportunities in India for storing river floodwaters in coastal reservoir. The paper also presents the concept of Sarovar Mala, a chain of coastal reservoirs, an innovative concept that has the potential to ensure water availability to India throughout the year.

Challenges and opportunities for coastal reservoir development in India

In a reinforced soil bed system reinforcement layer is usually placed with or without end anchorage. Since soil is weak in tension reinforcement develop tension under the applied load or the displacement of the footing. This tensile force is distributed along the length of the reinforcement subjected to the end condition. The reinforccement tension helps in distributing the load over a wider area, and becomes more effective at large induced settlements. As a result, vertical componenent of tensile force generated becomes effective in reducing applied load. However, very few studies to quantify the tensile force along the reinforcement have been reported in the literature. In this paper an attempt has been made to obtain the true nature of tensile force distribution along the reinforcement. For a reinforced soil bed below a strip footing this paper brings out induced tensile force distribution along the reinforcement at different load levels and for different types of reinforcements.

T. G. Sitharam

Papers

Numerical Simulation of Resonant Column Tests on Jointed Rocks Using DEM

Response of Embedded Structures in Granular Material to Air-Blast Wave Loading

Prediction of extension test results of soft cemented clays with a simple constitutive model

Challenges and opportunities for coastal reservoir development in India

Tensile force distribution along the reinforcement for reinforced soil foundations