Earth Fill Research Articles

Stability Analysis and Field Behaviour of Earth Fills on an Alluvial Marine Clay

Five erth fills for preloading were constructed on an alluvial marine clay under factor of safety of about 1. 0. One erth fill failed and two must have been on the position of failure. First, undrained strength characteristics of the clay at the proposed site are described and discussed as well as the procedure for determining the undrained strength for practical use. Settlement characteristics observed in the field for each earth fill are then reported. Stability analysis for actually constructed earth fills are shown, in which anisotropy in undrained strength and effect of strain rate on undrained strength were considered. The results showed excellent agreement with the field behaviour of each fill and strongly demonstrated that the undrained strength of the clay at the proposed site should be evaluated from consolidated undrained strength tests in which the specimens from undisturbed samples are reconsolidated at the same stresses they carried in the field.

The Eskimo Point water supply program

Eskimo Point, Northwest Territories, is a predominantly Inuit community of about 900 people, located on the west shore of Hudson Bay. Formerly, its water supply was obtained from nearby small, sometimes polluted, shallow lakes, which freeze to the bottom in winter, necessitating an ice-cutting operation. In 1973, a study was undertaken to investigate alternative methods of improving Eskimo Point's water supply. The recommended solution was the construction of a 6 500 000 gal (29 548 350 L) earth fill reservoir, lined with a hypalon membrane.Further field investigations and detailed design of the facility were carried out in 1974. All long-term delivery items were pre-ordered, and a general contractor was selected through public tender. Utilization of local manpower and equipment was specified.Construction commenced in mid-June of 1975 with the contractor providing on-the-job training to local Inuit, who adapted quickly to the equipment. Within 2 weeks, an all-local labour force was working around the clock constructing the reservoir embankments. Placement of a membrane liner of approximately 3.5 acres (1.4 ha) took 1 week, and was followed by placement of a protective layer of fill over the liner. Through good cooperation among owner, supplier, contractor, and engineer, the reservoir was completed in the fall of 1975 in time to be filled with water from a lake approximately 1 mi (1.6 km) away.

Theoretical seismograms for block structures

In constructing theoretical seismograms for large models with block structures, approximate methods are particularly efficient. For example, in treating Earth's crust block models, the ray method with various modifications for including diffracted waves can be used. Smaller block structures, of dimensions comparable to a wavelength, are efficiently treated by direct numerical methods. In this way practically important problems of engineering seismology, seismic microzoning, etc., can be solved. The method of so-called conservative diference schemes combines effectively the advantageous features of both the standard finite element and finite difference methods. The basic properties of the method, as well as some features of the corresponding Fortran IV program LATER, are explained on a computational example. The example concerns a highly simplified evaluation of the seismic response of the earth fill. In the frequency range under study two resonance frequencies are identified. Moving along the surface of the fill, from the base to the peak, the predominant frequency decreases. Some prospects of direct numerical methods in seismology are briefly discussed in concluding section.

Walls of reinforced earth

A French innovation, the technique of reinforcing earth fill with steel strips and a support facing of steel or precast concrete is an economical way of building retaining walls, embankments and the like. Knowledge of their structural behaviour is, however, largely empirical. Here, the authors review international developments and describe recent Hungarian work to test newer theories of dynamic as well as static response.

Installation of Fiberglass Pipe

A comprehensive review is made of the proposed ASTM X-23-8-15 Standard Recommended Practice forUnderground Installation of Flexible Reinforced Thermosetting Resin Pipe and Reinforced Plastic Mortar Pipe currently in the approval process. An in-depth evaluation is developed showing flexible design methods that account for the pipe zone material and the in-situ soil condition working together. The structural design of a buried conduit requires detailed calculation of the probable maximum load, determination of the inherent strength of the pipe and selection of a field or bedding condition which will ensure that the supporting strength of the completed structure will be adequate. ASCE Manual of Engineering Practice No.37 states, Flexible pipes under earth fills derive their ability to support load from their inherent strength plus the passive resistance pressure of the soil as they deflect and the sides of the pipe move outward against the soil side fills. High production and quality installation is keyed to lightweight and easy to assemble joining pipe systems.

Finite element analysis of reinforced earth wall

Reinforced earth consists of a soil mass whose engineering characteristics and performance have been improved by the introduction of small quantities of frictional material that possesses a relatively high tensile strength. The analysis of a reinforced earth system which incorporate metal strips placed at known intervals in the vertical and transverse directions within the soil mass is a complex problem. The complexity arises from the fact that reinforced earth is a three-dimensional problem and cannot be solved without imposing simplification with regard to the mechanical behavior of the system as well as the constitutive relationship governing the interaction between various components of the reinforced earth mass. The investigation reported herein describes a simplified approach for analyzing the instrumented reinforced earth wall which was previously constructed and loaded to failure at the U.S. Army Engineer Waterways Experiment Station. The three-dimensional problem was approximated by a structurally equivalent two-dimensional system and a two-dimensional finite element method was used in the analysis. The nonlinear behavior of the earth fill of the reinforced earth wall was simulated by hyperbolic formulation. The behavior of the metal skin element and reinforcing strips was assumed linear elastic until the yield stress was reached; thereafter, these metal components were assumed to fail plastically. Interface elements, to accommodate slippage between components of the reinforced earth wall, were also employed in the analysis. /Author/

Hydraulic Investigation of a Unique Proposal for the Carrot River Bridge Crossing

This paper gives details of the hydraulic investigation carried out for the proposed new bridge crossing over the Carrot River on Highway No. 23, near Carrot River, Saskatchewan. Geotechnical studies indicated that due to the very low shear strength of the highly plastic clay comprising the banks of the Carrot River, the river banks would not be capable of supporting the approach fills to the bridge. Highways Department engineers came up with the rather novel idea of placing a compacted clay fill or berm across the river at the bridge site in order to stabilize the banks. This introduced the problem of passing river flows through and over the berm. It was proposed that low flows should be carried through the berm by a culvert, and high flows should be passed over the berm by a spillway. Hence, the design envisaged a bridge over an earth fill and a spillway over a culvert, all at one site. A model study was considered essential because of the uncertain hydraulics and because a hydraulic failure could result in bridge failure.

Some Construction Aspects of Tarbela Dam

Tarbela Dam (Pakistan) including upstream blanket and two auxiliary dams requires 181,500,000 cu yd of earth and rock fill obtained two-thirds from borrow and one-third from required excavation. Nearly all materials are processed to attain desirable gradation. Placing rates have reached 301,000 cu yd per day and 6,550,000 cu yd per month. Excavation is by shovels up to 15-cu yd size, using 44-cu yd scrapers and 6-cu yd and 9-cu yd draglines. Hauling involves 110-ton bottom dump and 35-ton and 70-ton rear dump trucks. Processing separates various size ranges for zone requirements, or grizzlies out oversize material. Transport of materials up to 12 in. is largely by conveyor belt, from which bottom dump trucks distribute the materials. Compaction is handled principally by 10-ton vibratory rollers. Other earth and rock work includes a 6,000-ft airstrip, 8 miles of access road, cofferdams (4,500,000 cu yd), and a large switchyard.

Repair of Earthquake Damaged Underground Reservoir

A concrete underground water storage reservoir, damaged by earthquake, was repaired with epoxy compounds and by employing some unusual construction methods. Structural redesign and permanent removal of earth fill from the roof slab made it feasible to rehabilitate and strengthen the structure sufficient to meet seismic criteria that were judged to be compatible with the site conditions. The extensive use of epoxy repair techniques was instrumental in making it possible to salvage large portions of the walls and slabs without complete demolition and replacement, which was required for the most severely damaged areas. A substantial part of one exterior wall and adjacent displaced roof slab were successfully jacked back into original positions by a construction procedure that employed the use of heavy bridge shoring together with an array of hydraulic jacks.

Water quality effects of seepage from earthen dams

Analyses of surface and seepage waters from selected floodwater retarding structures in west-central Oklahoma, U.S.A. show the salinity of seepage to be several times greater than that of the impounded waters. The increases in concentration of the several chemical components are not proportional. This phenomenon appears to be caused largely by simple solution, which is closely related to the chemical character of the geologic formation that provides the reservoir site and the earth fill of the dam. Concentration of certain chemical components in the seepage water progressively decreases as the structure ages. This is probably a function of depletion, which is related to the amounts and solubility of the parent materials subjected to solution. In contrast, the concentration of certain other components, such as iron and calcium, increases with time. The chemical activities within the accumulating mud on the bottom of the reservoir apparently cause these increases.

Reinforced Earth Retaining Walls

Reinforced earth is a man-made earth fill in which thin bars, rods, fibers, or nets have been placed to improve the overall qualities of the soil. This paper describes the results of analytical and laboratory studies on small reinforced earth retaining walls. Experimental data were compared to analytical solutions for wall failure by either pullout or breaking of the reinforcing elements, and found to be in reasonable agreement. Cost estimates for prototype structures suggest that the cost of reinforced earth could be as low as half the cost of other conventional earth retaining walls.

Geological, Physical, and Mechanical Properties of “ Shirasu ” and its Engineering Classification

Shirasu in southern Kyushu is the deposits caused by volcanic activities, and structurally unstable. It is also called “special soil”. This paper contains the descriptions on the formation and constituents of Shirasu, the engineering classification, and the physical and mechanical properties, for estimating the stability of slopes in undisturbed Shirasu and compacted earth fills. Shirasu possesses grains of peculiar shape and surface texture, and its chemical components are composed dominantly of silica and alumina. As for mineral composition volcanic glass greatly surpasses others in quantity. Shirasu deposits can be classified into five distinct groups from the standpoint of soil engineering with its geological aspects in consideration. Physical and mechanical properties are different with the kinds of Shirasu due to engineering classification. Research is needed in order to develop the specification of designs of structures in and of Shirasu and to prevent and decrease in disaster.

Centro de exposiciones en Chicago – EE.UU.

This building, the reconstruction and enlargement of the old, fire-damaged Center of Expositions, has been executed in three levels consisting of various exhibition halls, theater, and complemented by cafeterias, restaurants, meeting rooms, dignitary suites, and parking facilities. The access and unloading platforms which serve the exhibition sites are located in the intermediate level. Principal characteristics are, on the one hand, the large area for pedestrians and automobiles, which separates the exhibition area from the theater area, and on the other hand, the structure. The 150-foot square bays for the two-way steel truss roof system impart a spaciousness consonant with the prior design concept. For this enlargement it was necessary to use part of the adjoining lake to effect retaining walls and earth fill in the newly acquired zones.

A Theoretical Study of the Pressures Acting on a Rigid Wall by a Sloping Earth or Rock Fill

The pressures acting on a rigid retaining wall by a sloping backfill of an idealized, c, ø, γ, material were evaluated by the theory of plasticity for both associated and non-associated flow rule materials. Lower bound solutions for passive pressure failure states were tirst established. The velocity field was then derived from the stress field and the kinematic admissibility of the velocity field for wall translation and rotation was investigated. Unique solutions were obtained for an associated flow rule material, provided the wall was translated or rotated about the base. A comparison of the theoretical values of the components of passive thrust for a ‘rough’ interface with reliable experimental values for a granular soil showed that the theoretical values for ø=øcv, ψ=0, agreed very closely with the measured ultimate values. The non-uniform strain distribution in the soil mass does not allow the simultaneous development of the peak stress ratio at all points in the failure zones, thus the plasticity solution with ø=ød (peak) and ψ= ψp (peak), or ød, can only provide an upper bound to the maximum possible passive thrust. The results presented in the Paper are applicable to the analysis of a gravity dam stabilized by a sloping earth or rock fill placed against the down-stream face. On a évalué les pressions qui agissent sur un mur de rétention rigide sous l'influence dun remblai en pente constitué d'un mat ériau idéalisé c, ø, γ au moyen de la théorie de la plasticit é pour des mat ériaux suivant ou ne suivant pas la règle de l'écoulement associé. On a d'abord établi les limites inférieures des états de rupture par but ée. On a alors déduit le champ des vitesses du champ des contraintes et on a étudié la possibilit é cinétique du champ de vitesses pour une translation et une rotation du mur. On a obtenu des solutions uniques dans le cas des mat ériaux qui suivent la règle de l'écoulement associé, en supposant que le mur était déplacé ou tourné relativement à sa base. On a montré, en comparant les valeurs théoriques des composantes de la but ée pour une surface de contact ‘rugueuse’ aux valeurs expérimentales mesurées sur un sol grenu, que les valeurs théoriques obtenues pour ø= øcv, ψ=0, correspondaient aux valeurs limites mesurées. La non-uniformit é de la distribution des déformations dans la masse du sol ne permet pas que le développement de la valeur maximum du rapport des contraintes se produise au même moment en tous les points des zônes de rupture, ce qui entraine que la solution obtenue au moyen de la théorie de la plasticit é pour ø= ød(max) et ψ=ψp(max) ou ød ne peut que fournir une limite supérieure de la but ée maximale possible. Les résultats présent és dans la communication peuvent être appliqués à l'analyse des barrages poids stabilisés par un talus en terre ou en remblai rocheux placé sur la face aval.

Schistosomiasis in Mainland China

This article is based on a review of about 250 published reports, largely in Chinese biomedical journals, on interviews with Chinese expatriates and Japanese scientists, and on news reports from communist, noncommunist, and neutral sources. It relates the progress made toward the control of schistosomiasis in mainland China during the past 20 years. In 1949, as a result of more than a half century of neglect of the public health, central China was ravaged by schistosomiasis japonica. In 11 provinces comprising 324 districts and some of the best rice-growing lands, villages were abandoned, fields lay fallow, famine was rife, and the surviving population was ill. Surveys showed that about 10.5 million persons had schistosomiasis and another 100 million were exposed constantly to the danger of infection; also, 1.5 million cattle were infected. A national campaign against the disease utilized the abundant manpower to destroy the snail host by cleaning irrigation ditches and streams and to reclaim lands by earth fills. Preventive measures have included storage of human feces to destroy eggs. Treatment of patients has relied upon traditional galenical drugs and a 3-day treatment with tartar emetic, with a maximum dosage of 700 mg. Research has produced a series of nitrofuran compounds, some of which have given promising results. There is little doubt that great progress has been made toward the control of schistosomiasis in China. Recently, owing at least in part to the Cultural Revolution, a 7-year plan to eradicate schistosomiasis has fallen behind schedule.

Cabin Creek Pumped Storage Hydroelectric Project

The Project consists of two reservoirs with a maximum head differential of 1,226 kw pump-turbine units. The upper reservoir is formed by a 210 ft high rock fill dam with a concrete facing with crest 11,202 ft above sea level. The dam at the lower reservoir is a combination earth and rock fill dam 95 ft high with sloping impervious core and upstream blanket. Geologic foundation conditions at each dam are described along with cross sections, elevations and outlines of construction specifications. The service requirements for dams for pumped storage projects are much more severe than most dams because of rapid daily drawdown and refill. The dams were monitored during and following construction. Records of deflection, settlement and seepage measurements are presented. In addition, some of the miscellaneous project features including erosion control, icing, and some of the project problems and solutions are described.

Design, Construction and Performance of Sesquilé Dam

Sesquilé Dam is a 41.5-m earth fill rolled dam with a thin inclined core, located near Bogotá, Colombia. Two uncommon features of this dam are the underwater excavation and uncompacted fill for the foundation of the main dam, and the unusual depth (80 m maximum) of the cut-off wall. Design expectations with regard to the as-built density characteristics of the underwater fill were surpassed through the use of strict but practical specifications, and by careful inspection of the dredging and dumping operations and sequences. Provisions to minimize cracking of the concrete cut-off included construction of the wall near the upstream toe after a large part of the fill had been built. No significant cracking of the wall has been detected in the seven years since closure of the dam. Potentially dangerous uplift pressures, have been treated satisfactorily by a relief-well system. Seepage losses through this system are within economically tolerable limits. The performance of Sesquilé Dam has been satisfactory.

Model and Prototype Tests of Buoyant Spillway Gates

Design of a radial gate, modified to obtain an opening torque, and with an additional upstream projection to obtain buoyancy for fail-safe operation is presented. Operating requirements for a full reservoir during the winter storm period precluded an uncontrolled spillway or holding gates open. An earth and rock fill dam, on the contrary, required fail-safe spillway control. A difficult site added to the design and cost problems. The gate, which evolved, can open to pass in excess of the flood of record without an external power source or without float wells, tripping devices, counterweights, or other accessories. Model tests were conducted to determine downpull effects of flow under the gate and through adjacent gates. Prototype tests under actual operating conditions were also conducted. Prototype and model test results are compared. Adjustable side plates replace conventional seals to eliminate seal friction but keep leakage to a tolerable limit. Operating experiences are also considered.

New Method of Measuring In-Situ Settlements

An inexpensive settlement gage is described. With this instrument it is possible to measure, outside the construction area, the settlements which occur within or below earth dams, fills or buildings with an accuracy of about 0.2 in. Some results from a load test where the new settlement gage has been used are also presented. The measured settlements agreed well with those obtained in a conventional manner with settlement platforms.

The I. C. O. S. method applied for the construction of cut-off wall for the auxiliary earth fill of Yagisawa Dam

Recently, in Japan, “ICOS” Method is introduced in earth improvement.On the build of Yagisawa dam, “ICOS” Method was adapted for the cut-off wall construction. This wall was successfully constructed. In this report, the author writes the outline of the construction, and sums up the points for the future.