ALBERT

Description / Table of Contents: Geochemistry is a science that is based on an understanding of chemical processes in the earth. One of the principal tools available to the chemist for understanding systems at equilibrium is thermodynamics. The awareness and application of thermodynamic techniques has increased at a very fast pace in geosciences; in fact, one may be so bold as to say that thermodynamics in geology has reached the "mature" stage, although much future thermodynamic research is certainly needed. However, the natural processes in the earth are often sluggish enough that a particular system may not reach equilibrium. This observation is being supported constantly by new experimental and field data available to the geochemist e.g. the non-applicability of the phase rule in some assemblages, the compositional inhomogeneities of mineral grains, the partial reaction rims surrounding original minerals, the lack of isotopic equilibration or the absence of minerals (e.g. dolomite), which should be present according to thermodynamics. The need to apply kinetics has produced a large number of papers dealing with kinetics in geochemistry. As an initial response to this growing field, a conference on geochemical transport and kinetics was conducted at Airlie House, VA, in 1973, sponsored by the Carnegie Institution of Washington. The papers there dealt with several kinetic topics including diffusion, exsolution, metasomatism and metamorphic layering. Since 1973 the number of kinetic papers has continued to increase greatly. Therefore, the time is ripe for a Short Course in Kinetics, which brings together the fundamentals needed to explain field observations using kinetic data. It is hoped that this book may serve, not only as a reference for researchers dealing with the rates of geochemical processes, but also as a text in courses on geochemical kinetics. One of us has found this need of a text in teaching a graduate course on geochemical kinetics at Harvard and at Penn State during the past several years. Finally, it is our hope that the book may itself further even more research into the rates of geochemical processes and into the quantification of geochemical observations. The book is organized with a rough temperature gradient in mind, i.e. low temperature kinetics at the beginning and igneous kinetics at the end (no prejudices are intended with this scheme!). However, the topics in each chapter are general enough that they can be applied often to any geochemical domain: sedimentary, metamorphic or igneous. The theory of kinetics operates at two complementary levels: the phenomenological and the atomistic. The former relies on macroscopic variables (e.g. temperature or concentrations) to describe the rates of reactions or the rates of transport; the latter relates the rates to the basic forces operating between the particular atomic or molecular species of any system. This book deals with both descriptions of the kinetics of geochemical processes. Chapter one sets the framework for the phenomenological theory of reaction rates. If any geochemical reaction is to be described quantitatively, the rate law must be experimentally obtained in a kinetically sound manner and the reaction mechanism must be understood. This applies to heterogeneous fluid-rock reactions such as those occurring during metamorphism, hydrothermal alteration or weathering as well as to homogeneous reactions. Chapter 2 extends the theory to the global kinetics of geochemical cycles. This enables the kinetic concepts of stability and feedback to be applied to the cycling of elements in the many reservoirs of the earth. Chapter 3 applies the phenomenological treatment of chapter 1 to diagenesis and weathering. The rate of dissolution of minerals as well as the chemical evolution of pore waters are discussed. The atomistic basis of rates of reaction, transition state theory, is introduced in Chapter 4. Transition state theory can be applied to relate the rate constants of geochemical reactions to the atomic processes taking place. This includes not only homogeneous reactions but also reactions that occur at the surface of minerals. Chapter 5 discusses the theory of irreversible thermodynamics and its application to petrology. The use of the second law of thermodynamics along with the expressions for the rate of entropy production in a system have been used successfully since 1935 to describe kinetic phenomena. The chapter applies the concepts to the growth of minerals during metamorphism as well as to the formation of differentiated layers (banding) in petrology. Chapter 6 describes the phenomenological theory of diffusion both in aqueous solutions and in minerals. In particular, the multicomponent nature of diffusion and its consequence in natural systems is elaborated. Chapter 7 provides the atomistic basis for the rates of reactions in minerals. Understanding of the rates of diffusion, conduction, order-disorder reactions or exsolution in minerals depends on proper description of the defects in the various mineral structures. Chapter 8 provides the kinetic theory of crystal nucleation and growth. While many of the concepts in the chapter can be applied to aqueous systems, the emphasis is on igneous processes occurring during crystallization of a melt. To fully understand both the mineral composition as well as the texture of igneous rocks, the processes whereby new crystals form and grow must be quantified by using kinetic theory. Due to space and time limitations (kinetics!) some topics have not been covered in detail. In particular, the mathematical solution of diffusion or conduction equations is discussed very well by Crank in his book, Mathematics of Diffusion, and so is not covered to a great extent here. The treatment of fluid flow (e.g. convection) is also not covered in the text.

Description / Table of Contents: During the austral summers of 1976-77 and 1978-79, several ice cores were taken from the McMurdo Ice Shelf brine zone to investigate its thermal, physical and chemical properties. This brine zone consists of a series of super-imposed brine layers (waves) that originate at the seaward edge of the ice shelf and migrate at various rates, depending upon their age and position in the ice shelf. The brine in these layers becomes increasingly concentrated as the waves migrate inland through the permeable ice shelf firn. Chemical analyses of brine samples from the youngest (uppermost) brine wave show that it contains sea salts in normal seawater proportions. Further inland, deeper and older brine layers, though highly saline (S 〉 200 ‰), are severely depleted in SO2-4 with the SO2-4/Na+ ratio being an order of magnitude less than that of normal seawater. Analyses of Na+, K+, Ca2+, Mg2+, SO2-4 and CI-, together with solubility and temperature considerations, show that the sulfate depletion is due to selective precipitation of mirabilite, Na2SO4*10H2O. The location of the inland boundary of brine penetration is closely related to the depth at which the brine en-counters the firn/ice transition. However, a small but measurable migration of brine is still occurring in otherwise impermeable ice; this is attributed to eutectic dissolution of the ice by concentrated brine as it moves into deeper and warmer parts of the McMurdo Ice Shelf.

Description / Table of Contents: Measurements and analysis of seasonal ice growth and decay on Post Pond, New Hampshire, for the period 1973-1982 are presented. Observations included ice thickness measurements, examination of the various ice types contributing to the ice cover, and measurements of meteorological parameters for correlation with and modeling of the ice growth process. The overall nature of ice growth and decay (ice loss) on the Post Pond has been ascertained, the seasonal variability in the timing of freeze-up and ice-out and the duration of the ice cover have been determined, and the relationship of ice growth to freezing-degree-day (deg C) records evaluated on the basis of a Stefan conduction equation modified to deal with ice sheets covered with or free of snow. Ice growth occurs predominantly by the direct freezing of lake water, but snow ice may compose as much as 50% of the ice cover in winters with higher than average snowfall. Freeze-up leading to the establishment of a stable ice cover occurs during the 4-week period from the end of November to the end of December. Maximum seasonal ice thicknesses were from 45 to 67 cm and are generally attained during the first two weeks of March; ice-out, marking the final disappearance of ice from Post Pond, usually occurs by the third week of April. The overall rate of the ice loss is three to four times that of ice growth, and is dominated initially by melting from the top. As much as 50% of the ice may be lost in this way before the onset of any bottom melting. Final dissipation of the ice cover is usually expedited by candling resulting from preferential melting and disintegration of the ice at crystal boundaries.

Description / Table of Contents: Peak power generation with hydropower creates tailwater flow conditions characterized by high and low flows with abrupt transitions between these states. Flows occurring in tailwaters typically form sharp-fronted, large-amplitude waves of relatively short period. An understanding of the mechanics of downstream propagation of these waves is important both for direct application in studies of the tailwater and because of the similarity of these waves to those following a dam break. An analysis of the dynamic equations of open channel flow is used to quantify the relative importance of flow wave convection, diffusion and dispersion in rivers. The relative importance of each process is re­lated to the relative magnitude of terms in the dynamic equations, providing a physical basis for model formulation. A one-dimensional diffusion wave flow routing model, modified for tailwaters, simulates the important physical pro­cesses affecting the flow and is straightforward to apply. The model is based upon a numerical solution of the kine­matic wave equation. The “modified equation,” Hirt, and von Neumann analyses are used to gain insight into the stability and dissipative and dispersive behavior of the numerical solution, and results of these analyses are compared. A set of linear routings is used to demonstrate the dissipative and dispersive behavior predicted by the analyses and to verify the accuracy of an expression that quantifies the numerical diffusion of the model. The analyses provide a basis for selection of numerical parameters for model applications. The capability and accuracy of the model are enhanced when physical wave diffusion is balanced by numerical diffusion in the model. Maintaining the diffusion balance re­quires that the time derivative weighting parameter 0 be variable and in some instances negative. Though some amount of phase error is introduced, negative 0 values have no adverse effect upon model stability. Field studies were con­ducted to demonstrate the benefits of careful model development and analysis, and to verify the diffusion wave model for rapidly varying tailwater flow. The bed slope and roughness characteristics of the field study reaches (below Apalachia and Norris Dams) differ greatly, spanning those of a large number of rivers of practical interest. The accurate simulation of flow in both of these tailwaters attests to the soundness of both the physical basis of the model and the numerical solution technique. The field studies confirm, for the extreme case of rapidly varying flow in a mildly sloped river, that inertia has a negligible effect upon unsteady flow waves at low Froude numbers. Additionally, these studies verify that diffusion of short-period waves in rivers is generally significant.

Description / Table of Contents: This report presents the results of dynamic ice-structure interaction model tests conducted at the CRREL Ice Engineering Facility. A flexible, single-pile, bottom-founded offshore structure was simulated by a test pile with about a one-to-ten scale ratio. Urea (instead of sodium chloride) was used as dopant to scale down the ice properties, resulting in good model ice properties. Six ice fields were frozen and 18 tests carried out. In all cases distinctive dynamic ice structure interaction vibrations appeared, from which abundant data were collected. In tests with linear ice velocity sweep, sawtooth-shaped ice force fluctuations occurred first. With increasing velocity the natural modes of the test pile were excited, and shifts from one mode to another occurred. The maximum ice force values appeared mostly with low loading rates, but high forces appeared random'y at high ice velocities. As a general trend, ice force maximums, averages and standard deviations decreased with increasing ice velocities. The aspect ratio effect of the ice force in continuous crushing follows the same dependence as in static loadings. The frequency of observed ice forces is strongly dominated by the natural modes of the structure. Dynamically unstable natural modes tend to make the developing ice force frequencies the same as the natural frequencies. Otherwise the resulting frequency depends directly on structural stiffness and ice velocity and inversely on the ice force range. During vibrations the displacement rates of the structure overcome the velocity of ice, making low loading rates and hence high ice forces possible. During crushing, ice induces both positive and negative damping.

Description / Table of Contents: A numerical model of rime ice accretion on an arbitrary two-dimensional airfoil is presented. The physics of the model are described and results are presented that demonstrate, by comparison with other theoretical data and experimental data, that the model predictions are believable. Results are also presented that illustrate the capability of the model to handle time-dependent rime ice accretion, taking into account the feedback between the ice accretion and the airflow and droplet trajectory fields.

Description / Table of Contents: Roof snow load case studies gathered throughout the United States over a three-year period are analyzed. The objective of the analysis is to determine a relationship between the snow load on the ground and the corresponding uniform snow load on flat and sloped roofs. The main parameters considered are the thermal characteristics of the roof, the roof slope and the exposure of the structure. Exposure has the strongest effect on the ratio of ground to roof snow loads. Comparisons are made with existing and proposed building codes and standards.

Description / Table of Contents: VHF-band radiowave short pulses were transmitted within the permafrost tunnel at Fox, Alaska, over distances between 2.2 and 10.5 m. The propagation medium was a frozen silt containing both disseminated and massive ice with temperatures varying from -7°C near the transmitter to probably -2 C near the center of the tunnel overburden. The short pulses underwent practically no dispersion in the coldest zones but did disperse and refract through the warmer overburden, as suggested by calculations of the effective dielectric constant. Most significantly the measured frequency content decreased as the effective dielectric constant increased. The results indicate that deep, cross-borehole pulse transmissions over distances greater than 10 m might be possible, especially when the ground is no warmer than -4°C. The information thus pined could be used for identifying major subsurface variations, including ground ice features.

Description / Table of Contents: This report investigates the influences of turbulence and water temperature on frazil ice formation. The rate and thequantity of frazil ice formed in a specified volume of supercooled water increase with both increasing turbulence inten-sitv and decreasing water temperature. The influence of turbulence intensity on the rate of frazil ice formation, how-ever. is more pronounced for larger initial supercooling. The turbulence characteristics of a flow affect the rate offrazil ice formation by governing the temperature to which the flow can be supercooled, by influencing heat transferfrom the frazil ice to surrounding water, and by promoting collision nucleation, particle and floc rupture and increasingthe number of nucleation sites. larger frazil ice particles formed in water supercooled to lower temperatures. The par-ticles usually were disks, with diameters several orders greater than their thickness. Particle size generally decreased with increasing turbulence intensity. This report develops an analytical model, in which the rate of frazil ice formation isrelated to temperature rise of a turbulent volume of water from the release of latent heat of fusion of liquid water toice. Experiments conducted in a turbulence jar with a heated, vertically oscillating grid served both to guide and tocalibrate thanalytical'model as well as to afford insights into frazil ice formation. The formation of frazil ice wasstudied for Vemperatures of supercooled water ranging from -0.9° to -0.050°C.

Description / Table of Contents: Measurements of meltwater pH from annual layers of South Pole firn and ice samples ranging in age from 40 to 2000 years B.P. show that precipitation at this remote site has a higher natural acidity than that expected from atmospheric equilibrium with CO2. The average pH of deaerated (CO2-free) samples was 5.64 + or - 0.08, while air-equilibrated samples averaged 5.37 + or - 0.008, a pH that is about a factor of two more acidic than the expected background pH of 5.65. The observed 'excess' acidity can be accounted for by natural SO4(2)- and NO(3)- levels in the samples probably originating from non-anthropogenic H2SO4 and HNO3. Because of the presence of these naturally occurring acids in South Pole precipitation, a pH of 5.4 is considered a more representative baseline reference pH for acid precipitation studies.

Description / Table of Contents: A mathematical model is described that is used to determine the maximum ice conveyance capacity of a river channel. Based upon this model, computer programs were developed that enable the ice discharge to be calculated for steady-state flow conditions. For rivers that have uniform flow, the maximum ice-conveying capacity can be described with a simple function expressed in terms of the size of the ice fragments, channel geometry, and the flow of water in the river. For nonuniform flows, the computer program determines the elevation profile of the surface layer in addition to other flow characteristics, such as the velocity and surface concentration of the ice fragments. The location along this surface profile where the ice conveyance capacity becomes less than the upstream supply is determined and is considered to be the position where a surface ice jam or ice bridge will be formed.

Description / Table of Contents: Ice forces on a bridge pier in the Ottauquechee River, in Quechee, Vermont, were measured by installing fourpanels-each capable of measuring forces in the normal and tangential direction - on both sides of a vertical V-shaped pier nose. The measured forces are presented for a short period during an ice run. After the ice run, the thickness and sizes of the ice floes were measured and the compressive strength of the ice was determined in the laboratory from the ice samples collected along the river banks. The water level measurements made at several locations along theriver are also presented for the period of the ice run.

Description / Table of Contents: A thermodynamic model has been developed that for the first time describes the entire creep process, including primary, secondary, and tertiary creep, and failure for both constant stress (CSR) tests (σ= const.) and constant strain rate (CSR) tests (ϵ = const.), in the form of a unified constitutive equation and unified failure criteria. Deformation and failure areconsidered as a single thermoactivated process in which the dominant role belongs to the change of entropy. Failure occurs when the entropy change is zero. At that moment the strain rates in CS tests reach the minima and stress in CSR tests reaches the maximum (peak) values. Families of creep (ϵ vs τ) and stress-strain (σ vs ϵ) curves, obtained from uni-axial compression CS and CSR tests of frozen soil, respectively (both presented in dimensionless coordinates), are plotted as straight lines and are superposed, confirming the unity of the deformation and failure process and the validity of the model. A method is developed for determining the parameters of the model, so that creep deformation and the stress-strain relationship of ductile materials such as soils can be predicted based upon information obtained from either type of test.

Description / Table of Contents: The results of resistance tests in level ice and broken ice channels are presented for two models of the WTGB 140-fticebreaker at scales of 1:10 and 1:24, respectively. No scale effect on the resistance in level ice could be detected between the two models. From the test results an empirical predictor equation for the full scale ice resistance is derived. Predicted resistance is compared against, and found to be 25 to 40% larger than, available full-scale values estimated from thrust measurements during full-scale trials of the Great Lakes icebreaker Katmai Bay.

Description / Table of Contents: Ice problems developed in the Sault Ste. Marie, Michigan, portion of the St. Marys River because of winter navigation. Passing ships and natural influences moved ice from Soo Harbor into Little Rapids Cut in sufficient quantities to jam, cause high water in the harbor, and prevent further ship passage. After physical model and engineering studies, two ice booms with a total span of 1375 ft (419 m) with a 250-ft (76-m) navigation opening between were installed at the head of Little Rapids Cut in 1975. A modest field study program on the booms was conducted for the ensuring four winters to determine ice and boom interaction and the effects of ship passages on the system. Forces on some anchors were recorded and supplemental data were taken by local personnel. Several reports have been written about the booms' early operations. This paper presents four-year summary of the main effects of the booms on ice and ship interaction and vice versa. Throughout the four winter seasons, the small quantities of ice lost over and between the booms were manageable. Ships usually passed through the boom without influencing the boom force levels, but at time they brought about large changes. One boom needed strengthening, and artificial islands were added for upstream ice stability. Coast Guard icebreakers were also a necessary part of winter navigation in this area.

Description / Table of Contents: Diatom species composition and relative abundances were determined for ice cores obtained from Weddell Sea pack ice during the October-November 1981 Weddell Polynya Expedition (WEPOLEX). Ice thickness and salinity indicate that the ice was less than one year old. The predominant ice type (70%) was frazil, which has the capacity to mechanically incorporate biological material through nucleation and scavenging. Diatoms were found throughout the length of the cores. Species showed down-core fluctuations in abundance that appeared to be correlated with changes in ice type. Pennate forms were more abundant than centrics, the average ratio being 16:1. Diatom frustules with intact organic material were more abundant (5 billion cells/liter). Differences in species abundances are attributed initially to incorporation of algal cells from a temporally changing water column and subsequently to diatom reproduction within the ice. Scanning electron micrographs illustrating the morphologic characteristics of the predominant species are included.

Description / Table of Contents: Experiments were conducted in CRREL's refrigerated flume facility to examine the two-dimensional force distribution of a floating, fragmented ice cover restrained by a boom in a simulated river channel. To determine the force distribution, a vertically walled channel, instrumented for measuring normal and tangential forces, and an instrumented restraining boom were installed in a 40.0- by 1.3-m flume. Two sizes of polyethylene blocks and two similar sizes of fresh-water ice blocks were tested using water velocities ranging from 10 to 30 cm/s. The forces measured at the instrumented boom leveled off with increasing cover length. The contribution of the increasing shear forces developed along theshorelines to this leveling off in the data was clearly evident. The shear coefficients of the polyethylene blocks averaged 0.43, and the freshwater ice averaged 0.044. The normal force measured along the instrumented shoreline could not be related simply by a K coefficient to the longitudinal force; another expression was required, with a term being a function of the cover thickness and independent of the undercover shear stress or cover length. By adding this term, good agreement was then found between the measured and predicted values of the boom forces and the shoreline normal and shear forces

Description / Table of Contents: An expression relating aerosol growth to cold environmental conditions was developed. This was accomplished by solving the diffusion equation with the method of Laplace transformation. The series solution was expressed in terms of the dimensionless parameters K (ratio of vapor density over droplet surface to droplet density), ω (ratio of environmental vapor density at time zero to vapor density over droplet surface), and dimensionless time τ (ratio of product of diffusion coefficient D and time t to square of initial radius of condensation nucleus). To take into account the variation of the vapor density over the surface of an acidic condensation nucleus due to the continuous dilution of the droplet, the solution was obtained by assuming various levels of constant vapor concentration. The final expression [R/R sub o - 1 = 2.4917 x 10 to the minus 18th power) exp(0.0737 θ) (P sub RHS/25) x (100-P sub RHS) τ to the 0.9890 powder] can be used to compute the value of R once the values of initial radius R sub o, relative humidity P sub RH, percent of relative humidity at the droplet surface P sub RHS, and environmental temperature θ are given.

Description / Table of Contents: Seismic P and SH wave refraction experiments at the NATO RSG-11 test site in Munster Nord, Federal Republic of Germany, reveal the presence of a nearly horizontal, three-layer velocity structure. The upper layer, composed of un­consolidated glacial till, is 1 m thick and has P (compressional) and SH (shear-horizontal) wave velocities of 240 and 165 m s-1. The second layer, made up of similar, more compacted material, is 9.5 m thick, with a P wave velocity of 470 m s-1 and an SH wave velocity of 275 m s-1. The third layer, interpreted as the groundwater table, is located at a depth of 10.5 m and has a P wave velocity of 1590 m s-1. The SH wave velocity of this layer is controlled by the matrix material and is the same as that of the second layer. A single, unreversed observation indicated a fourth layer at a depth of about 20 m, but the existence of this layer remains unconfirmed. The observed fundamental mode Love wave dispersion is in agreement with the theoretical dispersion predicted by the refraction velocities. Computed partial derivatives of phase velocity with respect to shear wave velocity show, for the frequencies observed, that the dispersion confirms the thicknesses and velocities of the two upper layers and is not affected by the deeper structure.

Description / Table of Contents: Snow and ice control on highways has come to rely heavily on the use of sodium chloride to maintain a trafficable surface for unimpeded movement. Empirical approaches have led to a wide range of application rates, some clearly excessive, but justified on the ground of safety and expediency. The combination of environmental degradation from the huge quantities of salt entering the environment, along with the increased cost of salt itself and the cost of its application have spurred the search for more precise knowledge of the proper amount of salt to apply to a pavement, considering a range of environmental, traffic and chemical parameters. Since controlled tests in the field are extremely difficult to make, a circular test track of three test pavements, dense-graded asphaltic concrete (DGA), open-graded asphaltic concrete (DGA) and portland cement concrete (PCC), was constructed in a coldroom. Natural snow and ice were applied to the pavements and an instrumented slipping wheel was driven over the surfaces to generate frictional forces. These forces were measured and then used to evaluate the response to salt application with time for three test temperatures. OGA had the lowest friction values at a temperature near the freezing point, but higher initial values or more rapidly increasing values than DGA and PCC following salt application at the two lower temperatures. Optimum application rate of salt on PCC and DGA lies between 100 and 300 lb/lane mile (LM), and a higher rate resulted in slight or no improvement in friction. DGA showed anomalous results: lower friction for 300 Ib/LM and higher friction for both 100 and 500 Ib/LM.

Description / Table of Contents: Investigations of the in situ complex dielectric constant of sea ice were made using time-domain spectroscopy. It was found that (1) for sea ice with a preferred horizontal crystal c-axis alignment, the anisotropy of polarizing properties of the ice increased with depth, (2) brine inclusion conductivity increased with decreasing temperature down to about -8 C, at which point the conductivity decreased with decreasing temperature, (3) the DC conductivity of sea ice increased with increasing brine volume, (4) the real part of the complex dielectric constant is strongly dependent upon brine volume but less dependent upon the brine inclusion orientation, (5) the imaginary part of the complex dielectric constant was strongly dependent upon brine inclusion orientation but much less dependent upon brine volume. Because the electromagnetic (EM) properties of sea ice are dependent upon the physical state of the ice, which is continually changing, it appears that only trends in the relationships between the EM properties of natural sea ice and its brine volume and brine inclusion microstructure can be established.

Description / Table of Contents: This report investigates the feasibility of clearing ice from the shipping channel of the St. Marys River. Four basic concepts are investigated: disposal under the ice, disposal on top of the ice, slurrying, and rafting. Each technique was found to have application in limited portions of the river with the exception of disposal on top of the adjacent ice sheet which is deemed feasible throughout the river system. Disposal onto the adjacent ice sheet will increase the free stream velocity less than 1.0 ft/s (30.5 cm/s) and raise the water level less than 1.0 ft (0.30 m). Further model and field tests are recommended to validate the findings of this report.

Description / Table of Contents: Explosive cratering tests were conducted in seasonally frozen and thawed gravel at Ft. Richardson near Anchorage, Alaska, and in seasonallly frozen and thawed silt overlying permafrost and in silt permafrost at Ft. Wainwright near Fairbanks, Alaska. Explosive charge weights ranged from 26 to 3120 lb and charge burial depths ranged from about 3 to 40 ft. The cube root of the charge weight scaling was used to determine maximum scaled crater dimensions and optimum scaled depth of burial of the charge. Test results for frozen and thawed gravel were essentially the same because of the low moisture content and the relatively shallow depth of freezing (5 to 6 ft). The optimum depth of burial of the charge for maximizing the apparent radius and depth and the true radius was about 1.8 times the cube root of the charge weight for both the frozen and thawed conditions. In seasonally frozen silt overlying a talik and silt permafrost the maximum scaled crater dimensions and optimum scaled burial depths of the charge were smaller than for the thawed condition except for the true crater dimensions. The channeling of energy in the talik produces maximum crater dimensions and an optimum burial depth for the true crater that is larger than for the thawed condition. The results for the homogeneous silt permafrost were very similar to the frozen gravel results with much smaller maximum crater dimensions and smaller optimum charge burial depths than for the thawed silt overlying permafrost.

Description / Table of Contents: Low-frequency (10 Hz) volcanic earthquakes originate at a wide range of depths and occur before, during, and after magmatic eruptions. The characteristics of these earthquakes suggest that they are not typical tectonic events. Physically analogous processes occur in hydraulic fracturing of rock formations, low-frequency icequakes in temperate glaciers, and autoresonance in hydroelectric power stations. We propose that unsteady fluid flow in volcanic conduits is the common source mechanism of low-frequency volcanic earthquakes (tremor). The fluid dynamic source mechanism explains low-frequency earthquakes of arbitrary duration, magnitude, and depth of origin, as unsteady flow is independent of physical properties of the fluid and conduit. Fluid transients occur in both low-viscosity gases and high-viscosity liquids. A fluid transient analysis can be formulated as generally as is warranted by knowledge of the composition and physical properties of the fluid, material properties, geometry and roughness of the conduit, and boundary conditions. To demonstrate the analytical potential of the fluid dynamic theory, we consider a single-phase fluid, a melt of Mount Hood andeside at 1250 deg C, in which significant pressure and velocity variations occur only in the longitudinal direction.

Description / Table of Contents: Two new types of load cells for attachment to bridge piers and direct measurement of ice forces were developed and tested with one type being installed on a pier of the Yukon River Bridge northwest of Fairbanks, Alaska. Both types of load cells used beams supported by base plates and carried nose plates that were loaded by the ice. The loads were imposed at the beams at locations differing from the support reactions so that the loads developed moments in the beams. By instrumenting them with strain gauges, the loads could be measured. Details of the design of the load cells, the means of calculating the loads and experience obtained with load cells are discussed.

Description / Table of Contents: The contribution of brine layers to observed reflective anisotropy of sea ice at 100 MHz is quantitatively assessed. The sea ice is considered to be a stratified, inhomogeneous, anisotropic dielectric consisting of pure ice containing ordered arrays of conducting inclusions (brine layers). Below the transition zone, the ice is assumed to have constant azimuthal c-axis orientation within the horizontal plane, so that the orientation of brine layers is uniform. The brine layers are also assumed to become increasingly well-defined with depth, since adjacent brine inclusions tend to fuse together with increasing temperature. A theoretical explanation for observed reflective anisotropy is proposed in terms of an isotropic electric flux penetration into the brine layers. Penetration anisotropy and brine layer geometry are linked to anisotropy in the complex dielectric constant of sea ice. In order to illustrate the above effects we present a numerical method of approximating the reflected power of a plane wave pulse incident on a slab of sea ice. Mixture dielectric constants are calculated for two polarizations of the incident wave: 1) the electric field parallel to the c-axis direction, and 2) the electric field perpendicular to the c-axis direction. These dielectric constants are then used to calculate power reflection coefficients for the two polarizations. Significant bottom reflection (R ~ 0.08) occurs when the polariza-tion is parallel to the c-axis. However, when the polarization is perpendicular to the c-axis, the return may be almost completely extinguished (R 〈 0.001). This extinction is due primarily to absorptive loss associated with the conduct-ing inclusions and secondarily to an impedance match at the ice/water interface that results in transmission of the wave to the water without reflection.

Description / Table of Contents: Results of impulse radar studies of sea ice give support to the concept of a sea ice model in which the ice bottom is composed of an array of lossy parallel plate waveguides. The fundametal relation between the average bulk brine volume of sea ice and its electrical and strength properties is discussed as is the remote detection of under-ice current alignment. It was found that 1) the average effective bulk dielectric constant is dependent upon the average bulk brine volume of the sea ice; 2) sea ice anisotropy, arising from a bottom structure of crystal platelets with a preferred c-axis horizontal alignment, can be detected by radio echo sounding measurements made not only on the ice surface but also from an airborne platform; 3) the effective coefficient of reflection from the seaiIce bottom decreases with increasing average effective bulk dielectric constant of the ice, decreases with increasing bulk brine volume, and is typically one to two orders of magnitude lower dhan the coefficient of reflection from the ice surface; and 4) the losses In sea ice increase with increasing average bulk brine volume.

Description / Table of Contents: Construction pads made of snow were used to build two sections of the Trans Alaska Pipeline and a small gas pipeline during the winter of 1975-76. Construction during the winter has become increasingly common in the Arctic. Surface travel and the use of heavy construction equipment on the unprotected tundra have been severely restricted, even during the winter, so the use of temporary winter roads and construction pads built of snow and ice has been advocated and is being adopted. The three snow construction pads mentioned above were the first snow roads and construction pads used on a large scale in Alaska. Snow roads and construction pads have two objectives: to protect the underlying vegetation and upper layers of the ground, and to provide a hard, smooth surface for travel and the operation of equipment. Several types have been built, and a brief discussion is given of their history and classification systems. The three snow construction pads used in construction of the Trans-Alaska Pipeline and the small gas pipeline in 1975-76 were visited and observed while in use. The Globe Creek snow pad, about 50 miles north of Fairbanks, was built primarily of manufactured snow hauled to the site and watered. With very high densities this pad withstood heavy traffic and use by heavy construction equipment except on one steep slope. There, the use of tracked vehicles and vehicles without front wheel drive disaggregated the snow on and near the surface so that vehicles without front wheel drive were unable to climb the hill. The Toolik snow pad, just north of the Brooks Range, was built of compacted snow and proved capable of supporting the heaviest traffic and construction equipment. The fuel gasline snow pad ran from the northern Brooks Range to the Arctic Coast and also proved capable of supporting the necessary traffic. Both the Toolik snow pad and the fuel gasline snow pad failed in very early May because of unseasonably warm and clear weather before the associated construction projects were completed. However, the three snow pads must be considered successful. Common problems were the lack of snow, slopes, unseasonably warm spring weather, and inexperience on the part of contractors and construction personnel.

Description / Table of Contents: Specimens prepared from various types of ice without introducing excessive defects were tested at temperatures ranging from -2° to -190°C. These tests indicated slightly higher Charpy values at lower temperatures and in more highly dispersed material concentrations. Three modes of fracture occurred during testing. Depending on the temperature and the material composition, either of the first two modes, normal fracture or multiple fracture, will appear and will show a normal frequency distribution of Charpy values in each type of ice. The third mode, fracture from both ends,which frequently occurred in the NH4F doped ice, gave Charpy values two to five times higher than the mean value for normal fracture. It can, therefore, be concluded that certain types of doping can alter the mode of fracture, through which drastic modifications of impact resistance my be possible.

Description / Table of Contents: Ice accretion on structures built on the earth’s surface is discussed. Sources of water are the atmosphere or water bodies near or surrounding the structure. Ice types include frost, rime, glaze, and spray; properties and conditions governing their formation are presented. Methods of estimating accretion rates and total accretion on structures are given, and extracts from U.S. and Canadian codes for ice and wind loads on structures are included. Techniques for preventing or removing ice accretion are presented.

Description / Table of Contents: The acoustic emission response from fine-grained polycrystalline ice subjected to constant compressive loads was examined. A number of tests were conducted with the nominal stress ranging from 0.8 to 3.67 MPa at a temperature of -5 C. The acoustic emission response was recorded and the data are presented with respect to time and strain. The source of acoustic emissions in ice is considered in terms of the formation of both microfractures and visible fractures that develop without catastrophic failure of the ice. A model to describe the acoustic emission response is developed.

Description / Table of Contents: A historical review of research is presented to establish the state- of-the-art for analyzing the behavior of vehicles in shallow snow. From this review, the most comprehensive and promising model is put together to establish a first-cut performance prediction model for vehicles operating in shallow snow, slush, ice and thawing soils.

Description / Table of Contents: Field observations support the interpretation that differences in the strength of radar returns from the ice covers of lakes on the North Slope of Alaska can be used to determine where the lake is frozen completely to the bottom. An ice/frozen soil interface is indicated by a weak return and an ice/ water interface by a strong return. The immediate value of this result is that SLAR (side-looking airborne radar) imagery can now be used to prepare maps of large areas of the North Slope showing where the lakes are shallower or deeper than 1.7m (the approximate draft of the lake ice at the time of the SLAR flights). The bathymetry of these shallow lakes is largely unknown and is not obvious from their sizes or outlines. Such information could be very useful, for example in finding suitable year-round water supplies.

Description / Table of Contents: The reflection of solar radiation by a snow cover in situ and the apparent influence of selected substrates were examined in wavelength bands centered at 0.81, 1.04, 1.10, 1.30, 1.50 and 1.80 micrometers. Substrates included winter wheat, timothy, corn, alfalfa, grass, concrete and subsurface layers of 'crusty' snow and ice. Reasonable qualitative agreement between measurements and theoretical predictions was demonstrated, with indications of quantitative agreement in the definition of a 'semi-infinite depth' of snow cover. It was concluded that ultimate quantitative agreement between theory and measurement will require that an 'optically effective grain size' be defined in terms of physically measuarable dimensions or meteorologically predictable characteristics of the ice crystals composing the snowpack.

Description / Table of Contents: During the growing seasons of 1977, 1978, and 1979, revegetation techniques were studied on the Chena River Lakes Project, a flood control dam and levee near Fairbanks, Alaska, to find an optimal treatment for establishing permanent vegetation cover on the gravel structures. The treatments tested on plots at the dam andor levee involved three main variables 1 vegetation grass and clover seed andor willow cuttings, 2 mulch, mulch blanket, andor sludge, and 3 substrate gravel or fine-grained soil over the gravel base. The mulches were hay, wood-cellulose-fiber, peat moss, and Conwed Hydro Mulch 2000, which is a wood-cellulose-fiber mulch with a polysaccharide tackifier. A constant rate of fertilizer was applied to all plots except the control. A section of each plot was refertilized again in their third growing season to compare annual and biannual fertilization. The high fertilization rate produced above-average growth. Fescue, brome, and foxtail were the most productive species on the dam, while alsike cover was the most productive on the wetter levee site. When grass seed and willow cuttings were planted at the same time, willow survival and growth were reduced. Fertilization is required for at least two years to produce an acceptable permanent vegetation cover, although fine- grained soil or sludge reduces the amount of fertilizer needed in the second year. Third-year fertilization may not be necessary since the benefits of the second fertilization continue for at least two years. A sludge treatment refertilized during its second growing season produces the highest biomass recorded in this study.

Description / Table of Contents: This report develops a method of analysis for heat transmission systems operating under district heating load conditions. The method accounts for the effects of heat source and load characteristics. The use of thermal energy storage systems is outlined and advantages are given. The transmission model itself considers the following technical aspects: (1) frictional pressure losses in piping system, (2) pump characteristics, (3) pump driver characteristics, and (4) heat losses from the buried piping. The capital costs considered are the piping system and necessary pumps. Operation and maintenance costs include cost of heat loss and cost of pumping energy input. Allowances are also made for system maintenance and repair over the assumed lifetime.