Feet Of Sand Research Articles

Closure to “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Closure to “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Discussion of “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Discussion of “Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand”

Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand

Effect of Relative Density and Particle Morphology on the Bearing Capacity and Collapse Mechanism of Strip Footings in Sand

Experimental Study of Shape and Depth Factors and Deformations of Footings in Sand

Bearing capacity calculation is an important part of shallow foundation design. The expressions for the shape and depth factors available in the literature for bearing capacity calculation are mostly empirical and are based on results obtained using limit analysis or the method of characteristics assuming a soil that is perfectly plastic following an associated flow rule. This paper presents the results of an experimental program in which load tests were performed on model strip and square footings in silica sand prepared inside a half-cylindrical calibration chamber with a transparent visualization window. The results obtained from the model footing load tests show a significant dependence of footing penetration resistance on embedment depth. The load test results were subsequently used to determine experimentally the shape and depth factors for model strip and square footings in sand. To obtain the displacement and strain fields in the sand domain, the digital image correlation (DIC) technique was used to analyze the digital images collected at different stages during loading of the model footing. The DIC results provide insights into the magnitude and extent of the vertical and horizontal displacement and maximum shear strain contours below and around the footing base during penetration.

Comparison of a modified and traditional rapid infiltration basin for treatment of nutrients in wastewater effluent.

A traditional rapid infiltration basin (RIB) has been compared to a modified RIB constructed with manufactured biosorption-activated media (BAM) to evaluate nitrate removal from wastewater effluent. The RIBs are used for reclaimed and excess stormwater disposal. In this work, a mixture of clay, tire crumb, and sand (CTS) was selected to serve as the BAM material (Bold and Gold™ CTS media). Each RIB was constructed with two feet of either sand or BAM, covering more than 43,600 square feet of surface area. Over an eight-month period, loadings to the BAM RIB and traditional RIB each approximated 5.4 million gallons (MG) per acre. Water samples collected from lysimeters installed below the 2 foot of sand or BAM materials were analyzed for nutrients. Results suggest that under the conditions of the study BAM removed approximately 31% more nitrate-nitrites and total phosphorus than the traditional RIB. Additionally, BAM removed approximately 18% more total nitrogen than the traditional. PRACTITIONER POINTS: Biosorption-activated media (BAM) removed nitrate-nitrites from reclaimed water more effectively than sand in rapid infiltration basins. BAM could serve as an alternative media for nutrient removal from water prior to release to the environment. Total nitrogen removal was most influenced by NOx removal, with a few removals influenced by TKN. Nutrients could not be effectively removed using BAM or sand from reclaimed water at threshold concentrations below two parts per million.

The use of skirts to improve the performance of a footing in sand

This paper investigates the use of skirts to improve the bearing capacity and to reduce the settlement of a circular footing resting on dune sand. The skirts are fixed to the perimeter of the footings. A series of tests were conducted on model footings in a large tank and the footings were instrumented to measure normal stresses and settlement. The test results indicate that the skirts increase the bearing capacity and reduce the settlement of the footing. The improvement in the bearing capacity is up to about 470% for a surface footing with skirt of a depth of 1.25B. The skirts also reduced the settlement of the footings to as small as 17% of the original settlement of a surface footing without skirts. A modified bearing equation was proposed for circular footings with skirts. The proposed equation agrees quite well with published experimental results.

What are the Welfare Costs of Shoreline Loss? Housing Market Evidence from a Discontinuity Matching Design

This paper uses housing market data to estimate the welfare costs of shoreline loss along coastal beaches in Florida. I develop a forward-looking structural model of a housing market in which a time-variant housing characteristic (beach width) follows a Markov process. I use this model to provide an exact welfare interpretation for the coefficients from three empirical research designs: (1) a repeat-sales panel regression of housing prices on beach width; (2) a differences-in-differences approach based on sharp changes in beach width caused by beach nourishment projects; and (3) a new discontinuity matching research design that exploits capitalized housing price differentials created by predictable changes in future beach width. Using a unique panel dataset on housing sales, beach width survey measurements, and the timing of 204 beach nourishment projects along 300 miles of Florida's coastline, I then use each of these research designs to estimate homeowners' willingness to pay for an extra foot of sand. In contrast to previous work, I find that changes in beach width have little impact on housing prices, except possibly at very eroded beaches. The results imply that the welfare costs of sea level rise may be low up to a threshold, and then increase sharply.

An investigation of correlation factors linking footing resistance on sand with cone penetration test results

Significant research effort has led to improvements in our ability to estimate the ultimate bearing resistance of footings in sand. These techniques often estimate the footing resistance at relatively large displacements, typically 10% of the footing width, qb0.1. Cone Penetration Test (CPT) design methods typically link qb0.1 and qc through a constant reduction factor, α. A range of α factors for shallow footings have been proposed, some methods suggest that α is constant and while others that it varies with footing width and depth (or stress level). There is a dearth of field data with which to compare these correlation factors, in particular where foundation width and depth have been varied in the same ground conditions. For this reason finite element analyses have proven to be a useful tool for performing the parametric studies required to asses factors controlling α. This paper describes the results of numerical analyses performed to investigate α factors for soil profiles which were calibrated using the results of the CPT tests performed at a dense sand test-bed site. The numerical model was first used to perform parametric analyses to consider the effect of footing width, B and footing depth, D on the α factor mobilised in dense Blessington sand. In order to assess the effects of relative density, footing tests in a range of natural sands with variable in situ densities were modeled. The results of the finite element analyses suggest that a direct correlation between qb0.1 and qc can be established at a given test site which is independent of footing width and depth and is relatively weakly dependent on the sands relative density if the zone of influence of the foundation considered is large enough.

The Bearing Capacity of Circular Footings in Sand: Comparison between Model Tests and Numerical Simulations Based on a Nonlinear Mohr Failure Envelope

This paper presents the results of a series of triaxial tests with dry sand at confining pressures varying from 1.5 kPa to 100 kPa at relative densities of 0.20, 0.59, and 0.84. The results, which are in reasonable accordance with an equation given by Bolton, show that the friction angle is strongly dependent on the stress level and on the basis of the test results, a nonlinear Mohr failure criterion has been proposed. This yield criterion has been implemented in a finite element program and an analysis of the bearing capacity of a circular shaped model foundation, diameter 100 mm, has been conducted. Comparisons have been made with results from 1g model scale tests with a foundation of similar size and a good agreement between numerical results and test results has been found.

The Characteristics of the Snow-cover and Snowmelt Water Storage in Gurbantunggut Desert

Based on the field experiment and observation in the southern margin of the Gurbantunggut Desert,the characteristics of the snow distribution and snowmelt water storage in the sand soil,the efficiency of the snowfall water translated to soil water are analyzed and calculated.The main results including:(1) the snow in Gurbantonggut Desert belongs to Dry-cold type snow with low density.Based on snow depth,snow density and snow water equivalent,3 different periods of snow season are divided.There are snow accumulation period,snow maintenance period and snow melt period.The average snow density is changed between 0.14 to 0.27 g/cm3 in different period,and the average snow depth is 20 cm to 30 cm in general.(2) Spatial differences are existed for the snow-cover distribution.There are no regularity for the snow depths variation in the top,hill and foot of sand dunes.Compared with the topography,the main desert shrub—Haloxylon ammodendron with sparseness distribution has more evident effect for the snow-cover depth variation.(3) Vertical infiltration is the mainly hydrological process of the snowmelt water.There are no surface water delay and confluence process in the desert regions.The depth of wetted soil of the snowmelt water is about 40 cm to 80 cm.the wetted layer in top is deeper than flat land between sand dunes.(4) there is high water transfer and storage efficiency for the snowfall.78.8% to 92.0% of the snowfall water is transferred to the soil water.It is considered that the cold climate,sand dune topography,limited snowfall,low soil water content before the snowmelt and the high infiltration capacity are the main reason for the vertical infiltration and the high water transferred efficiency of the snowmelt water.

A field investigation of vertical footing response on sand

This paper presents the results from an experimental programme that studied the factors affecting the bearing resistance of shallow footings in sand. In particular, the tests considered the effects of the footing width and embedment depth on the pressure–settlement response. By comparing the results with field tests on full-scale footings, simple correlations between the bearing pressure mobilised at normalised settlement levels of 5% and 10% of the footing width and the cone penetration test qc value were studied. These correlations were found to be independent of footing size, embedment depth and sand state, although they were affected by creep. The rate of mobilisation of the footing resistance at low settlements was found to be strongly dependent on the initial soil state and the previous loading history. A simple non-linear elastic soil model was found to adequately predict this response.

Estimation of bearing capacity for multiple footings in sand

In the present study, the effects of multiple-footing configurations in sand on bearing capacity were investigated using field plate load tests and finite element analyses. Both strip and spread footings were considered in the finite element analyses. In each case, different footing distances were applied for the purposes of comparison among all of the results. From these results, it was observed that the load responses of multiple footings are similar to those of the single footing at distances greater than three times the footing width. Design equation and correlation parameters, necessary for quantifying the values of the bearing capacity ratio for the different multiple-footing configuration, were derived. Experimental test results from the literature were selected and used in verifying the proposed method.

Bearing capacity of strip and circular footings in sand using finite elements

Design of shallow foundations relies on bearing capacity values calculated using procedures that are based in part on solutions obtained using the method of characteristics, which assumes a soil following an associated flow rule. In this paper, we use the finite element method to determine the vertical bearing capacity of strip and circular footings resting on a sand layer. Analyses were performed using an elastic–perfectly plastic Mohr–Coulomb constitutive model. To investigate the effect of dilatancy angle on the footing bearing capacity, two series of analyses were performed, one using an associated flow rule and one using a non-associated flow rule. The study focuses on the values of the bearing capacity factors N q and N γ and of the shape factors s q and s γ for circular footings. Relationships for these factors that are valid for realistic pairs of friction angle and dilatancy angle values are also proposed.

Discussion: Two- and three-dimensional bearing capacity of footings in sand

Discussion: Two- and three-dimensional bearing capacity of footings in sand

Strain Influence Diagrams for Settlement Estimation of Both Isolated and Multiple Footings in Sand

Most of the existing methods for estimating settlements of footings in sand have been developed for either isolated square footings or for strip footings. The literature contains limited information on settlement analysis of rectangular footings, and, as a result, there is no way to accurately account for the effect of the footing length-to-width ratio on settlement. Additionally, no practical method exists for considering the interaction between neighboring footings in settlement estimates. In this paper, we use Schmertmann's frame- work to propose a method of settlement estimation that takes full account of both the footing length-to-width ratio and the proximity of neighboring footings. Three-dimensional nonlinear finite element analyses were performed for various multiple footing configurations. Plate load tests were performed in sands using both a single plate and two plates separated by various distances. The numerical and experimental results indicate that the shape of the footing expressed through its length-to-width ratio and the proximity of neighboring footings affect two parameters of the strain influence diagram which is the basis for the settlement estimation method: the depth to the peak influence factor Izp and the depth of the strain influence zone. We propose new strain influence diagrams for estimation of settlement under these more general conditions.

Two- and three-dimensional bearing capacity of footings in sand

Bearing capacity calculations are an important part of the design of foundations. Many of the terms in the bearing capacity equation, as it is used today in practice, are empirical. Shape factors could not be derived in the past because three-dimensional bearing capacity computations could not be performed with any degree of accuracy. Likewise, depth factors could not be determined because rigorous analyses of foundations embedded in the ground were not possible. In this paper, the bearing capacity of strip, square, circular and rectangular foundations in sand are determined for frictional soils following an associated flow rule using finite-element limit analysis. The results of the analyses are used to propose values of the shape and depth factors for calculation of the bearing capacity of foundations in sands using the traditional bearing capacity equation. The traditional bearing capacity equation is based on the assumption that effects of shape and depth can be considered separately for soil self-weight and surcharge (embedment) terms. This assumption is not realistic, so a different form of the bearing capacity equation is also proposed that does not rely on it.

Spread Footings in Sand: Load Settlement Curve Approach

A study of the assumptions involved in the ultimate bearing capacity equation indicates the shortcomings of that equation and load test data confirm these shortcomings. A new approach using a normalized load settlement curve is proposed to alleviate these shortcomings and to obtain the complete load settlement curve for a footing in sand. The normalization consists of plotting the mean footing pressure divided by a measure of the soil strength within the depth of influence of the footing versus the settlement divided by the footing width. It is shown that the normalized load settlement curve for a footing is independent of footing size and embedment. It is proposed to obtain the normalized curve point-by-point from a soil test. Because the deformation of the soil observed under full-scale footings during loading indicates a barreling effect similar to the soil deformation around a pressuremeter probe, the preboring pressuremeter curve is used to obtain the footing curve. The new method consists of transforming the preboring pressuremeter curve point-by-point into the footing load settlement curve. Load tests and numerical simulations are used to propose a method for a rectangular footing near a slope subjected to an eccentric and inclined load. The new method gives the complete load settlement curve for the footing and alleviates the problems identified with the bearing capacity equation.

Overview: EOR/IOR (January 2007)

Reserves are a key factor for any oil company. This year's EOR issue highlights field projects that increased reserves by use of enhanced oil recovery. Economic incremental-oil production from field projects that used three different technologies [CO2 huff ‘n’ puff, mobility-control polymer, and steam-assisted gravity-drainage (SAGD)] is discussed. Daqing Oilfield Co. Ltd., People's Republic of China, has several papers discussing its commercial polymer flood. An SPE Advanced Technology Workshop on chemical flooding in Daqing concluded with Daqing stating that 25% of its production results from polymer injection—250,000 B/D. One paper stated, "Unquestionably, the application is successful, and the accumulated output has exceeded 70 million tonnes" (more than 500 million bbl of oil). Of interest is a closely spaced pilot to expand the polymer flood to marginal reservoirs. The strategy was injection of different-molecular-weight polymers in a staged manner, from low to high molecular weight, into zones with permeabilities appropriate for the injected polymer. Reported oil rates increased 1.8 times in confined production wells. Ultimate oil recovery beyond waterflood was 11.7%, of which 5.2% resulted from polymer flooding. Sixteen CO2 huff ‘n’ puff projects were conducted on different wells in the Forest Reserve oil field in Trinidad and Tobago over the last 20 years. CO2 from an ammonia plant was injected into either inactive or poor oil producers. Average slug size was 1 MMscf of CO2 per foot of sand, with a 3- to 5-day soak period. Multiple huff ‘n’ puff cycles were effective in more than half the wells, with the second to fourth cycle being the most productive for the majority of wells. Oil-rate improvements from nothing to up to 60 times pre-CO2-injection values were observed. During the startup and early operation of horizontal SAGD wells, it is important to understand the flow distribution of bitumen and water along the horizontal reservoir interval. If this distribution is understood, the distribution of steam, injected either at the heel or toe of the steam injector, can be adjusted to optimize the startup and early operation of the SAGD pair. Total E&P Canada permanently installed optical fiber along its first Joslyn SAGD production well to monitor the temperature profile continuously during startup and production. Thus, good engineering, technology, and a willingness to try different approaches can increase reserves in very large as well as smaller applications. EOR/IOR additional reading available at the SPE eLibrary: www.spe.org SPE 101202 "Study of High-Concentration Polymer Flooding To Further Enhance Oil Recovery" by Yang Fulin, Daqing Oilfield Co. Ltd., et al. SPE 100117 "Application of Smart-Well Technology to the SACROC CO2 EOR Project: A Case Study" by J. Brnak, Kinder Morgan Production Co. LP, et al. SPE 100346 "Suplacu de Barcau Field—A Case History of a Successful In-Situ Combustion Exploitation" by A. Panait-Patica, Petrom S.A., et al.

Moisture (Phase 2): Site #1

October 01 2004 Moisture (Phase 2): Site #1 Bernard Perroud, Bernard Perroud 1000 Doreen Place #1, Venice, CA 90291, U.S.A. E-mail: perroudburns@earthlink.net. Project web site: www.moisture.greenmuseum.org. Search for other works by this author on: This Site Google Scholar Claude Willey, Claude Willey 2624 Highview Avenue, Altadena, CA 91001, U.S.A. E-mail: claudewilley@sbcglobal.net. Search for other works by this author on: This Site Google Scholar Deena Capparelli Deena Capparelli 2624 Highview Avenue, Altadena, CA 91001, U.S.A. E-mail: deenalisa@sbcglobal.net. Search for other works by this author on: This Site Google Scholar Author and Article Information Bernard Perroud 1000 Doreen Place #1, Venice, CA 90291, U.S.A. E-mail: perroudburns@earthlink.net. Project web site: www.moisture.greenmuseum.org. Claude Willey 2624 Highview Avenue, Altadena, CA 91001, U.S.A. E-mail: claudewilley@sbcglobal.net. Deena Capparelli 2624 Highview Avenue, Altadena, CA 91001, U.S.A. E-mail: deenalisa@sbcglobal.net. Online Issn: 1530-9282 Print Issn: 0024-094X © 2004 ISAST2004 Leonardo (2004) 37 (5): 369–371. https://doi.org/10.1162/leon.2004.37.5.369 Cite Icon Cite Permissions Share Icon Share Twitter LinkedIn Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Search Site Citation Bernard Perroud, Claude Willey, Deena Capparelli; Moisture (Phase 2): Site #1. Leonardo 2004; 37 (5): 369–371. doi: https://doi.org/10.1162/leon.2004.37.5.369 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsLeonardo Search Advanced Search This content is only available as a PDF. © 2004 ISAST2004 Article PDF first page preview Close Modal You do not currently have access to this content.

Estimation of Footing Settlement in Sand

The settlement of foundations under working load conditions is an important design consideration. Well‐designed foundations induce stress‐strain states in the soil that are neither in the linear elastic range nor in the range usually associated with perfect plasticity. Thus, in order to accurately predict working settlements, analyses that are more realistic than simple elastic analyses are required. The settlements of footings in sand are often estimated based on the results of in situ tests, particularly the standard penetration test (SPT) and the cone penetration test (CPT). In this article, we analyze the load‐settlement response of vertically loaded footings placed in sands using both the finite element method with a nonlinear stress‐strain model and the conventional elastic approach. Calculations are made for both normally consolidated and heavily overconsolidated sands with various relative densities. For each case, the cone penetration resistance qc is calculated using CONPOINT, a widely tested program that allows computation of qc based on cavity expansion analysis. Based on these analyses, we propose a procedure for the estimation of footing settlement in sands based on CPT results.