Valistuneita arvauksia : talousennusteiden osuvuus 1997-2001

Kirjoitus perustuu vuosikokousesitelmään Kansantaloudellisessa Yhdistyksessä 21.3.2002.

Regional Approach to Landslide Interpretation and Repair, TR-430, 2001

The objective of this report is to provide Iowa county engineers and highway maintenance personnel with procedures that will allow them to efficiently and effectively interpret and repair or avoid landslides. The research provides an overview of basic slope stability analyses that can be used to diagnose the cause and effect associated with a slope failure. Field evidence for identifying active or potential slope stability problems is outlined. A survey of county engineers provided data for presenting a slope stability risk map for the state of Iowa. Areas of high risk are along the western border and southeastern portion of the state. These regions contain deep to moderately deep loess. The central portion of the state is a low risk area where the surficial soils are glacial till or thin loess over till. In this region, the landslides appear to occur predominately in backslopes along deeply incised major rivers, such as the Des Moines River, or in foreslopes. The south-central portion of the state is an area of medium risk where failures are associated with steep backslopes and improperly compacted foreslopes. Soil shear strength data compiled from the Iowa DOT and consulting engineers files are correlated with geologic parent materials and mean values of shear strength parameters and unit weights were computed for glacial till, friable loess, plastic loess and local alluvium. Statistical tests demonstrate that friction angles and unit weights differ significantly but in some cases effective stress cohesion intercept and undrained shear strength data do not. Moreover, effective stress cohesion intercept and undrained shear strength data show a high degree of variability. The shear strength and unit weight data are used in slope stability analyses for both drained and undrained conditions to generate curves that can be used for a preliminary evaluation of the relative stability of slopes within the four materials. Reconnaissance trips to over fifty active and repaired landslides in Iowa suggest that, in general, landslides in Iowa are relatively shallow [i.e., failure surfaces less than 6 ft (2 m) deep] and are either translational or shallow rational. Two foreslope and two backslope failure case histories provide additional insights into slope stability problems and repair in Iowa. These include the observation that embankment soils compacted to less than 95% relative density show a marked strength decrease from soils at or above that density. Foreslopes constructed of soils derived from shale exhibit loss of strength as a result of weathering. In some situations, multiple causes of instability can be discerned from back analyses with the slope stability program XSTABL. In areas where the stratigraphy consists of loess over till or till over bedrock, the geologic contracts act as surfaces of groundwater accumulation that contribute to slope instability.

Yrittäminen ja sukupuolen moniulotteisuus : haaste tutkimukselle ja koulutukselle

Summary: Entrepreneurial activity and the multidimensionality of gender: a challenge to research and education

The Use of Abrasives in Winter Maintenance, TR-434, 2001

The use of abrasives in winter maintenance is a well-established practice. The sand or other abrasive is intended to increase friction between vehicles and the (often snow or ice covered) pavement. In many agencies (and in many Iowa Counties, the focus of this study) the use of sand is a standard part of winter maintenance. Yet very little information exists on the value of sanding as a winter maintenance procedure. Some studies suggest that friction gains from sanding are minimal. In addition, there are increasing environmental concerns about sanding. These concerns focus on air quality and stormwater quality issues. This report reviews the state of the practice of abrasive usage in Iowa Counties, and classifies that usage according to its effectiveness. Possible changes in practice (with respect to abrasive usage) are presented and discussed.

Acreage Answers, April-May 2001, Vol. 2, No. 2

Newsletter for those who reside on acreages in Iowa. Produced by the Iowa State University Extension Office.

Acreage Answers, February-March 2001, Vol.2, no.1

Newsletter for those who reside on acreages in Iowa. Produced by the Iowa State University Extension Office.

Acreage Answers, April-May 2001, Vol. 2, no.3

Newsletter for those who reside on acreages in Iowa. Produced by the Iowa State University Extension Office.

Acreage Answers, December 2000-January 2001, Vol. 1, no. 5

Newsletter for those who reside on acreages in Iowa. Produced by the Iowa State University Extension Office.

Acreage Answers, August-September 2001, Vol. 2, no.4

Newsletter for those who reside on acreages in Iowa. Produced by the Iowa State University Extension Office.