H B Seed

Bio: H B Seed is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Soil liquefaction & Liquefaction. The author has an hindex of 9, co-authored 9 publications receiving 1521 citations.

Simplified procedure for estimating dam and embankment earthquake-induced deformations

Abstract: The method uses the concept of yield acceleration but is based on the evaluation of the dynamic response of the embankment rather than a rigid body behavior. The yield accelerations, for a potential sliding mass, is estimated on the basis of the static undrained shear strength (with some reduction due to effects of cycling) using pseudostatic methods of stability analysis. The permanent deformations are estimated by numerical double integration of the time history of induced accelerations for various depths of the potential sliding mass. Design curves are presented that were developed on the basis of finite element response computations of embankments subjected to base accelerations representing earthquakes of magnitudes ranging between 6-4 and 8-2. The simplified procedure is illustrated by an example computation. The permanent deformations are estimated for a 135-ft (40-m) high sandy clay embankment that was shaken by a magnitude 8-2 earthquake and the results are compared with the observed field behavior.

Simplified procedure for estimating dam and embankment earthquake-induced deformations

Abstract: The method uses the concept of yield acceleration but is based on the evaluation of the dynamic response of the embankment rather than a rigid body behavior. The yield accelerations, for a potential sliding mass, is estimated on the basis of the static undrained shear strength (with some reduction due to effects of cycling) using pseudostatic methods of stability analysis. The permanent deformations are estimated by numerical double integration of the time history of induced accelerations for various depths of the potential sliding mass. Design curves are presented that were developed on the basis of finite element response computations of embankments subjected to base accelerations representing earthquakes of magnitudes ranging between 6-½ and 8-¼. The simplified procedure is illustrated by an example computation. The permanent deformations are estimated for a 135-ft (40-m) high sandy clay embankment that was shaken by a magnitude 8-¼ earthquake and the results are compared with the observed field behavior.

Stabilization of potentially liquefiable sand deposits using gravel drains

Abstract: The installation of a drainage system offers an attractive and economical procedure for stabilizing an otherwise potentially liquefiable sand deposit. Such a procedure has already been used in one case involving the construction of stone columns in a relatively loose sand deposit, and it is being proposed for stabilization of a medium dense sand layer. The paper presents a simplified theory that provides a convenient basis for evaluating the possible effectiveness of a grain drain system in such cases. Where appropriate, additional analyses may readily be made using a computer program (LARF) based on the theory presented, but for most practical cases, it is believed that the charts presented in the paper will provide for effective stabilization of potentially liquefiable sand deposits.

The slides in the San Fernando Dams during the earthquake of February 9, 1971

Abstract: The February 9, 1971 earthquake in San Fernando Valley, California, caused slides in the embankments of two old adjacent hydraulic fill dams. At the 140-ft high Lower dam, the entire upstream face slid into the reservoir leaving only 5 ft of freeboard. At the 65-ft high Upper dam, the entire embankment from the waterline to the downstream toe moved downstream 6 ft, leaving a scarp just below the reservoir level on the upstream face. It is concluded that the slide in the Lower dam resulted from the development of an extensive zone of liquefaction near the base of the embankment. Some liquefaction is also believed to have occurred in the Upper dam; however, since a significant body of the sand in the upstream and downstream shells of this dam retained considerable strength, complete failure could not occur and the movements were limited in extent. Conclusions are presented concerning the applicability of analytical procedures for predicting the failure and movements that occurred.

Influence of Seismic History on Liquefaction of Sands

Abstract: It is shown both analytically and experimentally that deposits of sand subjected to low magnitude earthquakes that are not sufficiently strong to cause liquefaction will develop an increased resistance to liquefaction in subsequent earthquakes even though they may undergo no significant change in density. Accordingly, in order to determine the liquefaction characteristics of a sand it is necessary to perform tests on samples having the same density and structure as the in-situ material and conduct the tests, whenever possible, with the correct in-situ value of K sub 0. The study also indicates that the standard penetration resistance (or any in-situ measure of penetration resistance) is likely to provide a reasonable index of the liquefaction characteristics of a saturated sand deposit. Available data on field performance have been summarized to develop a correlation between penetration resistance and the cyclic stress ratio at which liquefaction has been found to occur in the field. /ASCE/

Liquefaction and flow failure during earthquakes.

Abstract: Two aspects of seismically-induced liquefaction are discussed which are of vital engineering significance: the triggering condition and the consequences of liquefaction. The triggering condition is examined with respect to liquefaction analysis, note being taken of the onset condition which is governed by cyclic strength. Consequences of liquefaction are discussed with respect to post-seismic stability analysis, in which the residual strength plays a major role. Procedures used for liquefaction analysis based on the results of in situ sounding tests are introduced, and the applicability of this method for estimating associated ground settlements is discussed. The evaluation of residual strength requires a better understanding of undrained sand behaviour. Results of extensive laboratory rests on Japanese standard sand are examined and new index parameters are proposed to quantify undrained sand behaviour better. The results of laboratory tests on silty sands are examined in the same way. AH the results are...

Evaluation of Liquefaction Potential Using Field Performance Data

Abstract: The evolution of a simplified procedure for evaluating the liquefaction potential of sand deposits using data obtained from standard penetration tests is reviewed. Field data for sites which are known to have liquefied or not liquefied during earthquakes in the United States, Japan, China, Guatemala, Argentina, and other countries are presented to establish a criterion for evaluating the liquefaction potential of sands in Magnitude 7‐1/2 earthquakes. The results of this study are then extended to other magnitude earthquakes using a combination of laboratory and field data. Available information on the liquefaction resistance of silty sands is also reviewed and a simple procedure for considering the influence of silt content is proposed. A method is presented for using the field data to evaluate the possible magnitude of pore water pressure generation in sands and silty sands which remain stable during earthquake shaking. Finally, the applicability of other in situ field tests, such as the static cone pene...

Standard penetration test-based probabilistic and deterministic assessment of seismic soil liquefaction potential

Abstract: This paper presents new correlations for assessment of the likelihood of initiation (or “triggering”) of soil liquefaction. These new correlations eliminate several sources of bias intrinsic to previous, similar correlations, and provide greatly reduced overall uncertainty and variance. Key elements in the development of these new correlations are (1) accumulation of a significantly expanded database of field performance case histories; (2) use of improved knowledge and understanding of factors affecting interpretation of standard penetration test data; (3) incorporation of improved understanding of factors affecting site-specific earthquake ground motions (including directivity effects, site-specific response, etc.); (4) use of improved methods for assessment of in situ cyclic shear stress ratio; (5) screening of field data case histories on a quality/uncertainty basis; and (6) use of high-order probabilistic tools (Bayesian updating). The resulting relationships not only provide greatly reduced uncertai...

Simplified Procedure for Estimating Earthquake-Induced Deviatoric Slope Displacements

Abstract: A simplified semiempirical predictive relationship for estimating permanent displacements due to earthquake-induced deviatoric deformations is presented. It utilizes a nonlinear fully coupled stick-slip sliding block model to capture the dynamic performance of an earth dam, natural slope, compacted earth fill, or municipal solid-waste landfill. The primary source of uncertainty in assessing the likely performance of an earth/waste system during an earthquake is the input ground motion. Hence, a comprehensive database containing 688 recorded ground motions is used to compute seismic displacements. A seismic displacement model is developed that captures the primary influence of the system’s yield coefficient ( ky ) , its initial fundamental period ( Ts ) , and the ground motion’s spectral acceleration at a degraded period equal to 1.5 Ts . The model separates the probability of “zero” displacement (i.e., ⩽1 cm ) occurring from the distribution of “nonzero” displacement, so that very low values of calculated...