Showing papers on "Standard penetration test published in 1977"

Laboratory Standard Penetration Tests on Fine Sands

Abstract: The Standard Penetration Test (STP) is critically examined with respect to its ability to estimate relative density in situ. Twenty-six test specimens, 4-ft in diameter by 6-ft high, were constructed using Reid Bedford Model sand and Ottawa sand. Using field drilling equipment, the SPT was performed at three overburden pressures on test specimens built to various densities. The results are presented as a family of curves correlating relative density with the SPT N-values at the testing pressures. It is concluded that the SPT is fairly repeatable in homogeneous deposits; however, variations in density, structure, or lateral stress within the test medium will produce widely scattered N-values. Thus, estimates of in-situ relative densities from N-values should be considered gross values or trends and should not be interpreted as accurate determinations for any specific case.

SPT and Relative Density in Coarse Sands

Abstract: The Standard Penetration Test (SPT) is critically examined with respect to its ability to estimate relative density in situ. SPT's were performed using field drilling equipment at three overburden pressures on 4-ft (1.22-m) diam by 6-ft (1.83-m) high test specimens constructed using Platte River and Standard Concrete sands at three relative densities. The results are presented as a family of curves correlating relative density with SPT N values for the three testing pressures. This research was an extension of a previous SPT test series on Reid-Bedford Model and Ottawa sands. The results of testing the four sands were compared and a statistical analysis produced an empirical equation relating relative density to effective overburden pressure, N value, and coefficient of uniformity. Comparisons are also made between this work and the previous work of Gibbs and Holtz at the Bureau of Reclamation and Bazaraa at the University of Illinois.

Estimating Foundation Settlements in Residual Soils

Abstract: Settlement of shallow foundations supported on residual soils derived from igneous and metamorphic rock may be estimated by using pressuremeter modulus, E p m data obtained from in-situ pressuremeter tests. A profile of E p m is developed when the test is performed in a continuous manner below a foundation element. The modulus data developed by this test accounts for variations in soil structure and compressibility since it is performed in situ. A linear relationship is indicated between the log of Standard Penetration Test N value and pressuremeter modulus E p m . The pressuremeter modulus, E p m , is also shown to approximate the soil modulus of deformation, E s . Pressuremeter modulus profiles developed below several proposed structures are used along with a simplified distribution of vertical strain to estimate expected building settlements. Actual settlement of foundation elements in these structures indicates good correlation. The method of settlement analysis is outlined and an illustrative example is included.

Soil liquefaction procedures--a review

Abstract: Various procedures used for evaluating soil liquefaction are reviewed and compared. Major emphasis is given to the equivalent uniform cycle procedure and the cumulative damage approach. Simplified versions of these two procedures are used to evaluate the factor of safety against liquefaction for 41 actual cases where liquefaction has or has not occurred during past earthquakes. Good agreement was obtained between the actual observed behavior and the analytical results. Empirical correlations developed on the basis of Standard Penetration Test blow count data at sites that have been subjected to previous earthquakes are also mentioned. Liquefaction analyses performed for two sites using several of the methods described are presented. The results of these analyses gave similar factor of safety values. The need for careful selection of the input parameters and use of sound engineering judgement was found to be as important in liquefaction analyses as the methods used.

Correlation of the texas cone penetrometer test n-value with soil shear strength

Abstract: Improved correlations have been developed between the Texas Cone Penetrometer Test N-value and the shear strength of both cohesive and cohesionless soils. Correlations were also developed and compared with existing correlations for several shear strength parameters and the Standard Penetration Test N-value. Both field and laboratory investigations were conducted to obtain the necessary data to develop the correlations. Penetrometer test data and undisturbed soil samples were obtained from five test sites for cohesive soils and six test sites for cohesionless soils. Reasonably good correlations were developed between the unconsolidated-undrained shear strength and the penetrometer test N-value for cohesive soils including homogeneous clays of high plasticity and silty or sandy clays of low plasticity. In addition, a reasonably good correlation was developed between the drained shear strength and the penetrometer test N-value for cohensionless soils including poorly graded sands and silty sands. The currently used relationship between the effective angle of shearing resistance of cohesionless soils and the penetrometer test N-value was found to be a lower bound for the data obtained in this study. Finally, correlations were attempted between unit skin friction and unit point bearing obtained from bored and driven pile tests and the penetrometer test N-value. These correlations are considered preliminary because only a limited amount of data was available from the instrumented pile load tests. /FHWA/

Liquefaction Potential of Dams and Foundations. Report 2. Laboratory Standard Penetration Tests on Platte River Sand and Standard Concrete Sand.

Abstract: : The Standard Penetration Test (SPT) is critically examined with respect to its ability to estimate relative density in situ. Six test specimens, 4 ft in diameter by 6 ft high, were constructed using Platte River sand and Standard Concrete sand. SPT's were performed, using field drilling equipment, on specimens under three overburden pressures and constructed to three relative densities. The results are presented as a family of curves correlating relative density with SPT N-values at the three overburden pressures. This research is an extension of a previous test series on Reid Bedford Model sand and Ottawa sand. The results from tests of the four sands are compared, and a statistical analysis is presented which produced an empirical equation relating relative density to overburden pressure, SPT N-value, and coefficient of uniformity. Comparisons are also made between this work and that of Gibbs and Holtz at the Bureau of Reclamation and Bazaraa at the University of Illinois. Conclusions are presented based on both series of tests. (Author)

Liquefaction Potential of Dams and Foundations. Report 4. Determination of 'in situ' Density of Sands.

Abstract: : The use of undisturbed samples to evaluate in situ density and Standard Penetration Test (SPT) to estimate in situ relative density is reviewed. A procedure for obtaining high quality undisturbed samples of sands and the influence of this sampling procedure on the in situ relative density are discussed. The use of radiographs to evaluate sample quality is examined. As a result of studies reviewed, it is concluded that the SPT is not sufficiently accurate to be recommended for final evaluation of the density or relative density of a site unless site-specific correlations are developed. High quality undisturbed samples of sands may be obtained using a fixed-piston sampler and drilling mud. This sampling procedure yields very good samples in deposits of medium dense sands; however, the procedure tends to densify loose sands and loosen dense sands. (Author)