Browsing by Subject "Sandy soils"
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Item An investigation of the thermal conductivity of a sandy soil as a function of soil moisture content(Texas Tech University, 1986-05) Gupta, SunilEnergy consumption for heating and cooling of residential and non-residential buildings is a significant portion of the total amount of energy used in the United States. Space heating and cooling accounts for almost 25 percent of the total U.S. consumption (as much as is consumed by all of transportation) and the potential for savings is very large indeed (5). For the residential sector alone, space heating accounts for 65 percent of all residential energy with a further 5 percent for space cooling (5). Space heating and cooling is by far the largest component of energy use in this sector, and this alone accounts for almost 16 percent of the nation's total raw energy use and is supplied primarily by natural gas and petroleum products (5).Item Construction and monitoring of an experimental highway pavement section for a long-term study on the effectiveness of cement as a subgrade stabilizer in fine-grained soils(Texas Tech University, 1996-12) Seal, Ronald C.A field and laboratory study was begun in 1995 to evaluate the engineering behavior of a stabilized soil from two test sections beneath a reconstructed roadway. This roadway is designated FM 1343 and is located in Medina County, south of SH 90, approximately 20 miles west of San Antonio, Texas. One test section was stabilized using portland cement, the other with lime. This work was sponsored by the Texas Department of Transportation (TxDOT) to make comparisons of the two stabilization methods under similar conditions. Soil samples were obtained from both test sites. For comparison, similar tests were performed on the soil samples obtained from each site. Initial testing indicates that both stabilization methods are comparable in plasticity reduction, strength increase and durability. However, it is the intent of this research to also establish long term monitoring so that TxDOT can continue to collect data to evaluate fiiture performance. In establishing long term monitoring, instrumentation was installed at both test sites, and initial data collected. It is intended that TxDOT personnel will continue this data collection over the next 5 years. Additional long term monitoring will also be performed by TxDOT personnel over this 5 year period. Any valid conclusions from the initial long term monitoring data cannot be made at this time.Item Dynamic properties of sandy and gravelly soils(2003) Menq, Farn-yuh; Stokoe, Kenneth H.A two-part study was undertaken to evaluate the dynamic properties of nonplastic sandy and gravelly soils. The first part involved the development of a large-scale, multi-mode, free-free resonant column. This device is called the multi-mode device, MMD. Key benefits of this device are: (1) “relatively” large specimens (15 cm in diameter) can be tested, (2) background noise is greatly minimized, and (3) the point of “fixity” in resonance testing is conveniently positioned at the specimen mid-height during the first-mode resonance. With the MMD, three different measurements can be performed. These measurements are: (1) torsional resonance measurements, (2) longitudinal resonance measurements, and (3) direct-arrival, constrained compression wave measurements. These measurements allow linear and nonlinear measurements of shear modulus, G, and material damping ratio in shear, Ds, in addition to measurements of small-strain Young’s modulus, Emax, small-strain material-damping ratio in unconstrained compression, Dc,min, and small-strain constrained modulus, Mmax. These measurements can all be performed sequentially on the same specimen. The second part of the study involved using the MMD to evaluate the dynamic properties of sandy and gravelly soils. A total of 59 reconstituted specimens were tested to systematically investigate the effects of void ratio, e, effective confining pressure, σo', median grain size, D50, and uniformity coefficient, Cu, on modulus and material damping in shear as well as the effects of these parameters on Emax, Dc,min, and Mmax. Some findings are: (1) the large-scale, free-free device works well and is adaptable to construct larger devices, (2) the primary effect of increasing D50 is to increase small-strain shear modulus, Gmax, and decrease small-strain material damping ratio, Ds,min, (3) D50 has a similar effect on Emax and Mmax as on Gmax, (4) Ds,min and Dc,min of dry granular soils are generally lower than 1.0%, (5) σo' has a slightly larger effect on Gmax, Emax, and Mmax of loose, well graded granular materials than dense, uniform materials, and (6) reference strain, γr, (a shearing strain at which G/Gmax = 0.5) is mainly a function of σo' and Cu, while γr increases as σo' increases and Cu decreases.Item Laterally loaded rigid piers in sand and sandy soils(Texas Tech University, 1984-08) Tseng, Tong-jongIn this research a model has been described to analyze and design rigid piers in sand and sandy soils. This model utilizes several soil spring constants to analyze the resistance-displacement relationship of the pier in sand and sandy soils. The soil spring constants used are lateral spring constants, bottom vertical spring constant, bottom friction spring constant, bottom moment spring constant, and friction spring constants on the periphery of the pier. The most important aspect of obtaining the resistance-displacement relationship between the pier and the soils is to calculate the ultimate resistance capacity of each layer of soil, and the slope of the initial part of the resistance-displacement curve. These have been done efficiently and the results are promising that are described and discussed here. The minimum potential energy theorem is used to develop the system equations.Item