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H. W. Olsen

Publications and source records attributed to H. W. Olsen.

11 recordsLinked to original sources
USGS2024

Geologic control of severe expansive clay damage to a subdivision in the Pierre Shale, southwest Denver metropolitan area, Colorado

Shortly after construction of a subdivision in the southwest Denver metropolitan area in 1986, a portion of the subdivision built directly on steeply-dipping strata of the Pierre Shale began experiencing damaging differential movements, causing house foundations to fail and pavements to warp and crack. This formation is a Late Cretaceous marine clay-shale composed predominantly of fluvial mixed-layer illite/smectite and quartz. During deposition of the shale, periodic and explosive volcanism generated thin beds of bentonite, consisting initially of volcanic ash and subsequently altered to nearly pure smectite. Some of these bentonite beds were exposed in a trench adjacent to the subdivision and perpendicular to the strike of the steeply-dipping strata. The thickest bentonite beds correlated well with linear heave features that these beds parallel the bedrock strike throughout the subdivision were mapped via severely deformed pavements. Mineralogical data show the bentonite bed that correlates with the worst damage within the subdivision consists of about 62% smectite by weight with mixed-layer illite/smectite expandability of 92%. By comparison, a sample of the typical silty claystone, which is fluvial mixed-layer illite/smectite mixed with detrital quartz from the adjacent strata, had about 23% smectite by weight with 70% to 90% illite/smectite expandability. Geotechnical tests for swell potential show that samples of 2 bentonite beds swelled 39% to 43% compared to 2% to 8% for samples of the typical silty claystone. It is proposed that differential swell resulting from stratigraphically-controlled differences in clay mineralogy and grain-size is the primary factor controlling extreme damage for this geologic setting.

Clays and Clay Minerals↗
USGS2007

Steeply dipping heaving bedrock, Colorado: Part 1 - Heave features and physical geological framework

Differentially heaving bedrock has caused severe damage near the Denver metropolitan area. This paper describes heave-feature morphologies, the underlying bedrock framework, and their inter-relationship. The heave features are linear to curvilinear and may attain heights of 0.7 m (2.4 ft), widths of 58 m (190 ft), and lengths of 1,067 m (3,500 ft). They are nearly symmetrical to highly asymmetrical in cross section, with width-to-height ratios of 45:1 to 400:1, and most are oriented parallel with the mountain front. The bedrock consists of Mesozoic sedimentary formations having dip angles of 30 degrees to vertical to overturned. Mixed claystone-siltstone bedding sequences up to 36-m (118-ft) thick are common in the heave-prone areas, and interbeds of bentonite, limestone, or sandstone may be present. Highly fractured zones of weathered to variably weathered claystone extend to depths of 19.5 to 22.3 m (64 to 73 ft). Fracture spacings are 0.1 to 0.2 m (0.3 to 0.7 ft) in the weathered and variably weathered bedrock and up to 0.75 m (2.5 ft) in the underlying, unweathered bedrock. Curvilinear shear planes in the weathered claystone show thrust or reverse offsets up to 1.2 m (3.9 ft). Three associations between heave-feature morphologies and the geological framework are recognized: (1) Linear, symmetrical to asymmetrical heaves are associated with primary bedding composition changes. (2) Linear, highly asymmetrical heaves are associated with shear planes along bedding. (3) Curvi-linear, highly asymmetrical heaves are associated with bedding-oblique shear planes.

Environmental & Engineering Geoscience↗
USGS2007

Steeply dipping heaving bedrock, Colorado: Part 2 - Mineralogical and engineering properties

This paper describes the mineralogical and engineering properties of steeply dipping, differentially heaving bedrock, which has caused severe damage near the Denver area. Several field sites in heave-prone areas have been characterized using high sample densities, numerous testing methodologies, and thousands of sample tests. Hydrometer testing shows that the strata range from siltstone to claystone (33 to 66 percent clay) with occasional bentonite seams (53 to 98 percent clay mixed with calcite). From X-ray diffraction analyses, the claystone contains varying proportions of illite-smectite and discrete (pure) smectite, and the bentonite contains discrete smectite. Accessory minerals include pyrite, gypsum, calcite, and oxidized iron compounds. The dominant exchangeable cation is Ca2+, except where gypsum is prevalent, and Mg2+ and Na1+ are elevated. Scanning electron microscope analyses show that the clay fabric is deformed and porous and that pyrite is absent within the weathered zone. Unified Soil Classification for the claystone varies from CL to CH, and the bentonite is CH to MH. Average moisture content values are 17 percent for claystone and 32 percent for bentonite, and these are typically 0 to 5 percent lower than the plastic limit. Swell-consolidation and suction testing shows a full range of swelling potentials from low to very high. These findings confirm that type I (bed-parallel, symmetrical to asymmetrical) heave features are strongly associated with changes in bedrock composition and mineralogy. Composition changes are not necessarily a factor for type II (bed-parallel to bed-oblique, strongly asymmetrical) heave features, which are associated with movements along subsurface shear zones.

Environmental & Engineering Geoscience↗
USGS2007

Steeply dipping heaving bedrock, Colorado: Part 3 - Environmental controls and heaving processes

This paper examines the environmental processes and mechanisms that govern differential heaving in steeply dipping claystone bedrock near Denver, Colorado. Three potential heave mechanisms and causal processes were evaluated: (1) rebound expansion, from reduced overburden stress; (2) expansive gypsum-crystal precipitation, from oxidation of pyrite; and (3) swelling of clay minerals, from increased ground moisture. First, we documented the effect of short-term changes in overburden stress, atmospheric exposure, and ground moisture on bedrock at various field sites and in laboratory samples. Second, we documented differential heaving episodes in outcrops and at construction and developed sites. We found that unloading and exposure of the bedrock in construction-cut areas are essentially one-time processes that result in drying and desiccation of the near-surface bedrock, with no visible heaving response. In contrast, wetting produces a distinct swelling response in the claystone strata, and it may occur repeatedly as natural precipitation or from lawn irrigation. We documented 2.5 to 7.5 cm (1 to 3 in.) of differential heaving in 24 hours triggered by sudden infiltration of water at the exposed ground surface in outcrops and at construction sites. From these results, we interpret that rebound and pyrite weathering, both of which figure strongly into the long-term geologic evolution of the geologic framework, do not appear to be major heave mechanisms at these excavation depths. Heaving of the claystone takes two forms: (1) hydration swelling of dipping bentonitic beds or zones, and (2) hydration swelling within bedrock blocks accommodated by lateral, thrust-shear movements, along pre-existing bedding and fracture planes.

Environmental & Engineering Geoscience↗
USGS2000

Mineralogy-swelling potential relationships for expansive shales

The extent to which mineralogy and swelling potential is correlated in the expansive clays and shales is studied. Sites are selected in Cretaceous shales, including Pierre Shale, that are uplifted into steeply dipping strata near the foothills of the Rocky Mountains. Swelling potentials are obtained on limited suites of samples with conventional and labor-intensive schemes including Seed and Chen's schemes, and with swell-consolidation measurements in response to saturation, consolidation, and rebound in an oedometer. The results showing the percent total smectite provide a useful index of swelling potential concept defined by Seed and correlates well with the swelling potential indices developed by Seed, Chen, and McKeen.

Conference Paper↗
USGS1990

Matrix-controlled hydraulic properties of Mississippian and Pennsylvanian sandstones from the Michigan Basin

Hydraulic-conductivity measurements were made of 49 sandstone core plugs using a flow pump and a conventional triaxial confining apparatus. The sandstones tested are samples from the Marshall Sandstone and Grand River and Saginaw Formations, which are the principal bedrock aquifers in the Michigan basin. Sandstones ranging from poorly cemented to well cemented were selected to investigate matrix-controlled hydraulic properties as a function of degree of cementation. Hydraulic conductivities were measured for each sample over a range of effective stress (69 to 827 kilopascals); hydraulic conductivities for the sample suite range from 1.9 X 10 to 2.7 X 10 centimeters per second. This range of approximately seven orders in magnitude is indicative of local and regional differences in matrix-controlled hydraulic conductivities for Mississippian and Pennsylvanian bedrock aquifers in the Michigan basin.

Michigan↗
USGS1986

Piston core properties and disturbance effects.

Laboratory geotechnical data on piston cores for 31 sites on the mid-Atlantic Upper Continental Slope show the near-surface sediments vary from normally consolidated to somewhat overconsolidated clayey silts and silty clays of low to high plasticity. They also exhibit normalized behavior and their index property correlations with the effective-stress friction angle, the undrained strength ratio, and the compression index are reasonably consistent with existing knowledge. Because existing knowledge concerning disturbance effect suggests that in-situ preconsolidation stress values should lie between those derived from the triaxial and laboratory vane data, the preconsolidation stress values obtained from the consolidation data appear to be appreciably smaller than in-situ values. -from ASCE Publications Information

Journal of Geotechnical Engineering↗
USGS1985

Low gradient permeability measurements in a triaxial system

Permeability measurements were conducted with the flow-pump method on sand, sandy silt and silty clay specimens in a conventional triaxial system by introducing and withdrawing water at known constant flow rates into the base of a specimen with a flow-pump, and by monitoring the head difference induced across the length of the specimen with a sensitive differential pressure transducer. The results show that the previously reported advantages of the flow-pump method, compared with conventional constant head and falling head methods, were realized for permeability measurements in conventional triaxial equipment. These advantages are that direct flow rate measurements are avoided together with the associated errors that arise from the effects of contaminants on capillary menisci and the long periods of time involved in flow rate measurements; permeability measurements can be obtained much more rapidly and at substantially smaller gradients; errors from the small intercept in the otherwise linear flow rate versus hydraulic gradient relationship, and also from seepage-induced permeability changes, can easily be recognized and avoided or minimized. The results further show that the initial transient response of a specimen that precedes the steady state condition needed for a permeability measurement can require a substantial period of time. In this study the response times varied from a fraction of a minute for a sand specimen to more than 200 minutes for a silty clay specimen. Errors in permeability measurements from this transient response can easily be avoided with the flow-pump method but not with constant head and falling head methods.

Geotechnique↗
USGS1982

Geotechnical characteristics of bottom sediments in the northeastern Bering Sea.

Sediment of Holocene age derived from the Yukon River, consisting dominantly of silty fine sand and sandy silt, covers the bottom of central and western Norton Sound, which is a high energy environment involving extensive ice loading, high waves, and strong bottom currents. The sediment characteristics indicate that it is susceptible to liquefaction during major storms. Substantially finer grained, weak and highly compressible sediment of Holocene age covers eastern Norton Sound and the Port Clarence embayment, which are low energy environments. Pleistocene peaty deposits underlie the Holocene and late Pleistocene deposits in both Norton Sound and Chirikov Basin and are somewhat overconsolidated. The presence of gas indicates high in situ pore pressure and hence low material strength.-from Authors

Geologie en Mijnbouw↗