Analysis of pseudocolor transformations of ERTS-1 images of Southern California area

The author has identified the following significant results. Representative faults and lineaments, natural features on the Mojave Desert, and cultural features of the southern California area were studied on ERTS-1 images. The relative appearances of the features were compared on a band 4 and 5 subtraction image, its pseudocolor transformation, and pseudocolor images of bands 4, 5, and 7. Selected features were also evaluated in a test given students at the University of California, Los Angeles. Observations and the test revealed no significant improvement in the ability to detect and locate faults and lineaments on the pseudocolor transformations. With the exception of dry lake surfaces, no enhancement of the features studied was observed on the bands 4 and 5 subtraction images. Geologic and geographic features characterized by minor tonal differences on relatively flat surfaces were enhanced on some of the pseudocolor images

Fault tectonics and earthquake hazards in parts of southern California

The author has identified the following significant results. Four previously unknown faults were discovered in basement terrane of the Peninsular Ranges. These have been named the San Ysidro Creek fault, Thing Valley fault, Canyon City fault, and Warren Canyon fault. In addition fault gouge and breccia were recognized along the San Diego River fault. Study of features on Skylab imagery and review of geologic and seismic data suggest that the risk of a damaging earthquake is greater along the northwestern portion of the Elsinore fault than along the southeastern portion. Physiographic indicators of active faulting along the Garlock fault identifiable in Skylab imagery include scarps, linear ridges, shutter ridges, faceted ridges, linear valleys, undrained depressions and offset drainage. The following previously unrecognized fault segments are postulated for the Salton Trough Area: (1) An extension of a previously known fault in the San Andreas fault set located southeast of the Salton Sea; (2) An extension of the active San Jacinto fault zone along a tonal change in cultivated fields across Mexicali Valley ( the tonal change may represent different soil conditions along opposite sides of a fault). For the Skylab and LANDSAT images studied, pseudocolor transformations offer no advantages over the original images in the recognition of faults in Skylab and LANDSAT images. Alluvial deposits of different ages, a marble unit and iron oxide gossans of the Mojave Mining District are more readily differentiated on images prepared from ratios of individual bands of the S-192 multispectral scanner data. The San Andreas fault was also made more distinct in the 8/2 and 9/2 band ratios by enhancement of vegetation differences on opposite sides of the fault. Preliminary analysis indicates a significant earth resources potential for the discrimination of soil and rock types, including mineral alteration zones. This application should be actively pursued

Undrained stability of footings on slopes

Solutions for the ultimate bearing capacity of footings on purely cohesive slopes are obtained by applying finite element upper and lower bound methods. In a footing-on-slope system, the ultimate bearing capacity of the footing may be governed by either foundation failure or global slope failure. The combination of these two factors makes the problem difficult to solve using traditional methods. The importance of a dimensionless strength ratio in determining the footing capacity is broadly discussed, and design charts are presented for a wide range of parameters. In addition, the effect of footing roughness and surface surcharge are briefly quantified

Two- and three-dimensional undrained bearing capacity of embedded footings

The ability to predict the ultimate bearing capacity of a foundation is one of the most important problems in foundation engineering. To solve this problem, geotechnical engineers rountinely use a bearing capacity equation that contains a number of empirical factors to account for foundation shape, depth and inclination. In this paper finite element analysis is used to predict the undrained bearing capacity of strip, square, rectangular and circular footings embedded in clay. From these analyses, rigorous shape and depth factors have been derived and are compared with prvious numberical and empirical solutions in the literature. The bearing capacity behaviour is discussed and the bearing capacity factors are given for various cases involving a range of embedment depths and footing shapes

The ultimate undrained resistance of partially embedded pipelines

On-bottom pipelines for transporting oil and gas in deep water undergo significant changes in temperature and pressure during operating cycles, which cause a tendency for lateral buckling. Prediction and control of this phenomenon are required for the safe design and operation of these pipelines. However, the soil response under combined vertical and lateral loading is a significant area of uncertainty, and current practice relies on empirical expressions for the estimation of lateral pipe-soil resistance. This paper reports the results of finite element (FE) analyses of shallowly embedded pipelines under vertical and horizontal load. These analyses have been compared with collapse loads calculated using the upperbound theorem of plasticity, and are used to construct yield envelopes defining the limiting combinations of vertical and horizontal load. The FE limiting loads were found to compare well with upper-bound plasticity solutions, and the internal soil displacements calculated in the FE analyses match the upper-bound and experimentally observed deformation patterns. The yield envelopes generated by the FE and upper-bound analyses have been fitted by simple solutions, which aid assessment of the ultimate resistance of shallowly embedded pipelines.</p

The ultimate uplift capacity of multi-plate strip anchors in undrained clay

Soil anchors are commonly used as foundation systems for structures requiring uplift resistance such as transmission towers, or for structures requiring lateral resistance, such as sheet pile walls. Anchors commonly have more than one plate or bearing element and therefore there is a complex interaction between adjacent plates due to overlapping stress zones. This interaction will affect the failure mode and ultimate capacity. However, no thorough numerical analyses have been performed to determine the ultimate pullout loads of multi-plate anchors. By far the majority of the research has been directed toward the tensile uplift behaviour of single anchors (only one plate). The primary aim of this research paper is to use numerical modelling techniques to better understand plane strain multi-plate anchor foundation behaviour in clay soils. A practical design framework for multi-plate anchor foundations will be established to replace existing semi-empirical design methods that are inadequate and have been found to be excessively under or over conservative. This framework can then be used by design engineers to more confidently estimate the pullout capacity of multi-plate anchors under tension loading