A Study on Water Retention Characteristics of Fly Ash

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Evaluating the Utility of Fly Ash for Waste Containment Application

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Growth dynamics of deciduous species during their life period: A case study of urban green space in India

It is evident that grass density (GD) and shoot growth rate (SGR) governs the differential settlement of substructure, groundwater recharge, and stability of green infrastructure. GD and SGR are usually assumed to be constant during the entire life period of vegetation. However, spatial and temporal dynamics of GD and SGR in urban green space were rarely explored previously. The main objective of this study is to explore the spatial and temporal dynamics of GD and SGR in urban space vegetated with deciduous species (mix grass i.e., Poaceae and Bauhinia purpurea). Field monitoring was conducted in the urban green space for one year (i.e., life period of selected species). The monitoring period includes the growth period and gradual wilting period. Substantial spatial variation of GD was found during the first six months. GD away from the tree trunk was found to be 1.02–56.3 times higher than that near the tree trunk during the first six months. Thereafter, any spatial variation of GD was not found in the next six months. Unlike the GD, SGR was found to vary during the entire life period of mix grass. In addition, SGR away from the tree trunk was found to be 1.1–4.6 times higher than that near the tree trunk. Any relationship between GD and rainfall depth was not found. Whereas, SGR mainly depends on rainfall depth. The hypothesis of uniformity in GD and SGR during the life period of deciduous species was not found to be true

A study to investigate the influence of soil properties on suction

Various models that incorporate the influence of soil suction on different engineering properties of unsaturated soils have been developed. However, a systematic study of various physical parameters of the soil mass such as type of soil. particle size distribution. and the state of compaction (i.e., water content, dry unit weight, and saturation) is required to understand the influence of these parameters on soil;suction. directly or indirectly. This would be of great help in understanding the unsaturated properties of the soil mass. With this in view, an effort has been made in this technical note to measure the suction of locally available silty soil and commercially available white clay, compacted at different water contents and dry unit weights, using an insertion tensiometer. Efforts have been made to determine the influence of various parameters. as stated earlier, on the soil suction. Details of the test setup used for these studies are also presented

A critical review of the methodologies employed for suction measurement for developing the SWCC

Several methodologies have been developed and used by researchers for measuring either total suction ψ (sum of matric suction ψm and osmotic suction ψo), or only ψm. While employing different methodologies for establishing the soil-water characteristic curve, SWCC, there is a possibility that the factors such as the type of the soil suction measured, measurement range, equilibration time, presence of salts or contaminants in the soil etc., may influence it. Thus there is a need to understand the uniqueness of SWCC determined by using some of the commonly adopted methodologies such as insertion tensiometer, a pressure membrane extractor for measuring ψm, and a dew point potentiameter for measuring ψ. For this purpose, two locally available uncontaminated fine grained soils, of entirely different characteristics were considered in this study. In addition, to understand the influence of salt content on the SWCC, another chloride rich soil of marine origin was also considered. The study indicates that the SWCC established by using different methodologies may not be unique and hence due care should be taken while reporting the SWCC of a soil.© IACMA

Nonlinear curve-fitting procedures for developing soil-water characteristic curves

Measurement of soil suction for developing soil-water characteristic curve, SWCC, is a laborious and time-consuming task. On the other hand, commercially available databases that employ empirical fitting functions or the estimation algorithms for establishing the SWCC are quite costly and hence, beyond the reach of many. In such a situation, application of two simple nonlinear curve-fitting procedures (viz., a spreadsheet based program, SBP, and Levenberg-Marquardt Algorithm, LMA) for developing the drying SWCC was investigated. The utility and efficiency of these fitting procedures have been demonstrated by comparing the results vis-A-vis those obtained from a dewpoint potentiameter, WP4, and a knowledge-based database, KBD. In addition to this, efforts were made to develop correlations between the parameters used in the SWCC fitting functions and the physical properties of the soil, which can be determined quite easily by conducting routine laboratory tests. It has been demonstrated that these correlations can be used very efficiently for indirect estimation of the SWCC of the fine-grained soil

Generalized relationship for determining soil electrical resistivity from its thermal resistivity

The knowledge of soil electrical and thermal resistivity finds its application in many of the real life engineering projects like laying of high voltage buried power cables, ground modification techniques etc. This necessitates determination of soil electrical resistivity and thermal resistivity and development of a relationship between them. However, as these resistivities mainly depend on the type of the soil (i.e. its physical composition) and its saturation, efforts have been made in this paper, to develop a generalized relationship to relate them. Validation of the relationship has been conducted vis-a-vis the results obtained from the laboratory experiments and those reported in literature. (C) 200

Evaluation of various pedo-transfer functions for developing soil-water characteristic curve of a silty soil

This paper describes development of the soil-water characteristic curve (SWCC) of a silty soil by measuring its matric suction Psi(m), corresponding to different gravimetric water contents w. To achieve this, a field tensiometer and a dew point potentiameter (WP4) were employed. For this soil, the SWCC was determined indirectly using the estimation algorithms known as pedo-transfer functions (PTFs), which are based on volume-mass properties and the grain-size distribution characteristics, and are available in a commercial database SoilVision. In addition to this, experimental results were used for developing the SWCC of the soil, using various fitting functions cited in the literature and available in the database. An attempt has been made in this technical note to demonstrate the usefulness of these three methods for obtaining the SWCC of the silty soil. The study reveals that the PTFs developed previously to estimate SWCCs match very well with the experimental results

Bending behavior of hybrid-actuated piezoelectric sandwich beams

The finite element analysis is presented for hybrid-actuated piezoelectric sandwich beam structures. The hybrid actuation is modelled by incorporating a transversely polarized, d31-based extension actuation lamina and an axially polarized, d15-based shear actuation lamina. Further the bending behavior of sandwich beams are evaluated for various boundary conditions with segmented actuators. The active stiffening effect is assessed through bending deflection behavior. The extension and shear actuators are collocated as well as non-collocated along the length of beam to see the combined actuation effort. It is observed that for the clamped-free case, the actuation effect is augmented with collocated actuators; however this trend is not followed in the other cases. Interestingly, the non-collocated actuators show better cumulative actuation effort for different boundary conditions except in the hinged-hinged case, where shear actuation appears to be predominant. As extension and shear actuations have distinctive features, both can be employed in a non-collocated fashion for better control action