Performance of Earth Retention System, St. Louis Data Center

The design and performance of the earth retention system for a 35 ft deep excavation in medium clay is described. The earth retention system consisted of soldier piles and lagging with tieback anchors. One level of tiebacks included helical anchors installed in loose to medium dense sand. Behavior of the helical anchors in contrast to conventional drilled-in anchors is discussed

Soil Property Determination for a Seismic Study

Static and dynamic soil property data were needed for input into the seismic retrofit design for the I-155 Mississippi River crossing located near the center of the New Madrid Seismic Zone. Soils consisted of recent river alluvium underlain by very dense soils of the Mississippi embayment. The field investigation consisted of conventional borings, downhole geophysical tests to measure shear wave velocity, and seismic piezo-cone soundings. SPT energy measurements were made at one boring to confirm hammer energy for liquefaction evaluation. This paper summarizes the data and provides site specific correlation of shear wave velocity vs. N-value from the seismic cone and downhole geophysical tests; measured SPT energy value; and estimates of static and dynamic soil properties

Geotechnical Earthquake Engineering for the Great River Bridge

The proposed Great River Bridge is a 1400-foot long cable-stay structure that will be constructed over the Mississippi River between Desha County, Arkansas and Bolivar County, Mississippi. Including the bridge approach structures and approach embankments, the total structure length is approximately 23,500 feet. Seismic issues have controlled most of the structural design. Design ground motions for three typical subsurface profiles were developed and resulted in near-surface peak accelerations between 0.23 and 0.26g. Level ground liquefaction analyses indicated widespread liquefaction in an abandoned channel of the river and sporadic liquefaction elsewhere. Seismic slope stability and lateral spreading analyses indicated minor displacements at the approach embankments, the Arkansas levee, and the Mississippi riverbank; moderate displacements at the Mississippi levee; and major displacements at a 25-foot high natural terrace and the Arkansas riverbank. Conceptual liquefaction mitigation/soil improvement options were investigated

The Earth: Plasma Sources, Losses, and Transport Processes

This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed

Landslides on Shale in Southern Illinois

This paper presents the case histories of two landslides in southern Illinois. The first landslide presented occurred along a highway cut at Ford\u27s Hill on Illinois Route 3 near Chester, Illinois. The second landslide occurred in the embankment of a large retention pond in southern Illinois. Both failure planes were along the surface of the weathered shale bedrock in response to excess pore pressures. Backfigured strength at the time of failure was low and at the residual strength of the weathered shale