Settlements of Rigid Rectangular Footings on Layered Soils

Solutions to calculate the settlement of footings resting on a semi-infinite or finite soil layer are readily \ud available in the literature. Whitman and Richart (1967) proposed the vertical settlement factors for rigid \ud rectangular footing resting on a semi-infinite layer of soil. The equation takes into consideration the \ud aspect ratio, defined as ratio of length to width, L/B, of the footing through a parameter ‘βz’. Sovinc (1969) proposed the settlement factors for a rectangular footing on a finite layer of homogeneous soil underlain by a rigid base. He also considered the effect of L/B on the settlement of the footing. However, Sovinc’s solution is given only for one Poisson’s ratio value equal to 0.5

Numerical analysis of MSE wall considering wall friction and reinforcement stiffness

The existing methods widely used for the design of Mechanically Stabilized Earth walls (MSE) do not consider the effects of reinforcement stiffness andwall-soil interface friction angle on the mobilized lateral earth pressures. For example, FHWA code provides the variation of the coefficient of lateral earth pressure, K, based on the type of reinforcement (extensible or inextensible reinforcement). The code recommends higher K values for MSE wall with inextensible reinforcement than that with extensible reinforcement. However, the reinforcement stiffness values corresponding to inextensible or extensible reinforcements are not defined in the code. In addition, the variation of K with depth is not available for intermediate values of reinforcement stiffness. Wall-soil interface friction angle is another important parameter that affects the mobilized lateral earth pressures. In the present study, Finite Difference Program (Fast Lagrangian Analysis of Continua FLAC) is used to study the effects of reinforcement stiffness and wall-soil interface friction angle on the lateral earth pressures for an active condition

Relationship between meaning of death and burnout among nurses caring for patients with neurologicial intractable illness

The purpose of this study was to examine on the relation ship between meaning of death and burnout among nurses caring for patients with neurological intractable illness. Questionnaire investigation was carried out to thirty-five nurses working in the wards for the patients. The results were as follow: 1) There was a positive correlation between negative meaning of death such as avoidance of thinking about death and burnout such as emotional exhaustion and depersonalization. 2) There was a positive correlation between positive meaning of death such as meaningfulness of death for life or death acceptance by belief in the afterlife and personal accomplishment. These finding were discussed from the viewpoint of nursing patients with neurological intractable illness

Environmental feasibility and implications in using recycled construction and demolition waste aggregates in road construction based on leaching and life cycle assessment – A state-of-the-art review

Environmental feasibility and implications in using recycled construction and demolition waste aggregates in road construction based on leaching and life cycle assessment – A state-of-the-art revie

笹淵友一著「北村透谷」

Mixtures of shredded tyres with sand have become accepted geo-materials in the past decade, especially for use as fill materials. Owing to the large size of tyre shreds commonly used in practice, large-scale direct shear testing equipment is specially fabricated to obtain the shear strength parameters of mixtures. The effect of tyre shred-tosand mixing ratio on the mechanical response of the mixtures is studied by performing direct shear tests on mixtures prepared at different mixing ratios. Out of the four types of samples tested, three (with mixing ratios of 20/80, 25/75 and 35/65 by weight of tyre shreds to sand) are prepared using 50 to 100 mm long tyre shreds and one (25/75 by weight of tyre chips to sand) using tyre chips with nominal size of 9.5 mm. The end-of-test friction angle of all the tyre shred-sand mixtures considered in this research is in the 30-33 degrees range. Results of direct shear testing from the present study and other studies in the literature show that the shear strength of tyre shred-sand mixtures is greater than that of tyre chip-sand mixtures because the elongated tyre shred pieces are able to provide greater reinforcement effects than are possible with equidimensional (cubical) tyre chips

Compaction Quality Control of Earth Fills Using Dynamic Cone Penetrometer

Quality control for compaction of earth fills is commonly performed by measuring the in situ density using the sand cone method. In situ density measurements from sand cone testing are highly operator-dependent; in addition, the test procedure is tedious and time-consuming. In this study, a dynamic cone penetrometer (DCP) was used to perform quality control (QC) of earthworks by measuring penetration resistance in compacted soil. DCP tests were performed on three test pads specially constructed using different soil types - clayey sand with gravel, clayey sand, and silty sand. The test results were expressed in terms of a dynamic penetration index (DPI), defined as the depth of penetration of the cone per hammer blow. Correlations are developed between DPI and compacted density for the three soil types considered. In order to meet the criterion of compacted density equal to or greater than 98% of the maximum density from a laboratory standard Proctor test, DPI values are found to range from 5 to 8 mm/blow, corresponding to 250 mm penetration of cone on tested soil types. The effect of the fall height of the hammer on the measured DPI is also studied by performing DCP tests for two fall heights, 575 and 450 mm. DPI values are found to increase by 11-26% when the height of the fall increases from 450 to 575 mm, for the highest energy level considered in the study. It is also found that DPI is very sensitive to the moisture content and in situ density of compacted layers. The DCP device provided quick test results and was simple to operate on any subgrade layer; hence, the frequency of QC tests can be increased, leading to an improvement in the overall quality of compaction of earthworks

Evaluation of Waste Foundry Sand and Blast Furnace Steel Slag as Geomaterials

Based on index properties in laboratory testing, foundry sand, and blast furnace steel slag may be considered as a construction backfill alternative. Naturally available granular materials for various fill applications are fast dwindling and sometimes not readily available near every construction site. In the current scenario, there is a substantial need to use alternative geomaterials. Many industry by-products and waste materials [fly ash, copper slag, bottom ash, construction, and demolition wastes (C&D), etc.] have been extensively studied for their suitability as a geomaterial. Steel slag generation in the world was estimated to be in the range of 170-250 MT in 2015, and considerable amounts of waste foundry sand are also generated. In the present study, waste foundry sand from Ordnance Factory, Medak, India, and blast furnace (BF) steel slag from Tata Steel, Jamshedpur, India, are tested for basic characteristics including gradation, specific gravity, morphology, chemical composition, and compaction. The engineering properties, shear strength, and permeability, are evaluated. In addition, leachate studies are conducted to assess the environmental impact of use of these materials for the proposed applications. Compaction behaviour of both the materials is found to be similar to granular soils. Foundry sand and BF steel slag exhibited an angle of shearing resistance of 31 0 and 37 0 , respectively. A comparative study on the properties of foundry sand and BF steel slag with the conventional fill material is performed, and the two waste products considered in the study are assessed for fill applications

A new mixing technique for randomly distributed fibre-reinforced expansive soil

In the state of Gujarat, India, a significant part of the area is covered by expansive soil deposits. The swelling and shrinkage characteristics of expansive soil as a result of wetting and drying cause problems for safety and/or performance of structures. The concept of reinforcing soil with fibres, resulting in a randomly distributed fibre-reinforced soil (RDFS), has been studied in significant details, especially for reinforcing granular soils. Studies on fibre-reinforced expansive soils as reported in the literature are very limited. One of the major problems in the study of fibre-reinforced expansive soils is how to mix fibres uniformly. Therefore, the main objective of this paper is to study the available mixing methods, assess their suitability and develop a new mixing technique, which will be cost-effective for mixing fibres with expansive soil, especially in developing countries. In the present study, a surface modification method with cement has been proposed, where the waste tyre fibres (WTFs) were coated with cement to improve the bonding between fibres and clay minerals. The effect of this modification on the strength property of reinforced soil has been examined with unconfined compressive strength analysis. The results show that the shear strength between cement coated fibres and soil is significantly higher than the shear strength between fibres and natural soil