Showing papers on "Soil stabilization published in 1977"

Energy Method for Soil Stability Analyses

Abstract: A method for soil stability analyses applying principles of soil mechanics to the theory of plasticity (limit analysis approach) is presented. The rigorous theoretical background and the simplicity of both the method and the calculation procedure are encouraging application of the method in engineering practice. Attention is drawn to the implication of the boundary conditions of deformations (degrees-of-freedom of the investigated structure or support) for the analysis. Different numbers of degrees-of-freedom of a system generally yield different results for safety factor, bearing capacity, etc. The method can be used for bearing capacity, earth pressure, and slope stability analyses. It is applicable for: (1)Design and failure conditions; (2)short and long-term analyses; (3)soil with pore water that is either stagnant or in seepage motion; (4)layered medium; and (5)arbitrary number of degrees-of-freedom of structure or support.

Deep stabilization of soft cohesive soils

Abstract: This report presents a new method for improving the bearing capacity and shear strength at relatively large depths of soft cohesive soils, mainly clay. A stabilizing agent, mainly unslaked lime, is forced down to the desired depth and mixed with the soil by a rotating auger or by a tool formed in the shape of a giant egg whisk. Thus relatively uniform columns of stabilized soils are formed in the ground with the same diameter as that of the auger. In this way foundations for buildings and other structures are safer and less expensive to construct in comparison with other foundation methods. The method has been tested, and results obtained so far indicate that the stabilized columns appreciably reduce the total settlements and almost entirely eliminate the differential settlements. /TRRL/

Dispersive Clay in Irrigation Dams in Thailand

Abstract: Since 1970, a number of earth dams in northeast Thailand have suffered serious tunnel and surface erosion from rainfall, and several have failed during the first reservoir filling. The behavior is typical of dams containing dispersive clay. This paper describes the testing program undertaken to evaluate the embankment and foundation materials, and discusses the results. Laboratory testing included chemical analysis of the saturation extract, the U.S. Soil Conservation Service dispersion test and X-ray diffraction. Some correlation was found between the test results and the extent of the damage to various embankments. In the search for nondispersive soil, the Emerson Crumb Test has been used for initial indications in the field, as well as being used, with modifications, in the laboratory. A description is given of measures being adopted to repair two damaged dams with dispersive soil where nondispersive soil is not available. The repairs involve the replacement of eroded material and the prevention of any serious future damage to existing and new materials by physical and chemical treatments.

Encountering Dispersive Clays on Soil Conservation Service projects in Oklahoma

Abstract: Dispersive clays occur frequently in nature, possessing properties detrimental to agronomic tillage practices and to engineering structures such as dams, terraces, channels, etc. Surface erosion occurs readily, since the fines are easily detached and suspended in runoff water. Where water can enter cracks in dispersive clays, subsurface erosion usually develops rapidly and extensively in areas of strong relief under favorable climatic conditions. For many years, the Soil Conservation Service has relied upon the Laboratory Dispersion Test as the benchmark for identification of these problem clays. Improved sampling techniques and the supplementary use of two field identification tests have been extremely helpful in recent years, particularly in embankment zoning. Liming the surface layers of dispersed clay embankments has provided a satisfactory means for stabilization. Three lime-treatment jobs have not been damaged in seven years. Aluminum sulfate is being evaluated on a field trial basis.

Tunnel-Gully erosion and urban development: A case study

Abstract: An area of tunnel gully erosion induced by the excavation of a drain through a residential subdivision in Southern New South Wales was examined. Twelve months after excavation, tunnels extend 7 m from the drain wall and threaten residential blocks only 5 m further away. A survey of a major tunnel by excavation and probing indicated tunnel formation along soil cracks around large (50 to 100 cm diameter) structural units. Soil analyses rated the soil as highly dispersible by all the routine tests used by the Soil Conservation Service (SCS) of New South Wales, namely, Emerson's Crumb Test, Ritchie's Dispersal Index, and Floyd's Sticky Point Test, and showed that this dispersibility could be attributed to a high exchangeable sodium percentage (ESP) (mean 10.5). In addition, the soil had a low volume expansion (<5 percent) and was relatively impermeable. These analyses have been compared with published criteria to show that the soil could have been identified as highly susceptible to tunnel erosion prior to excavation. This would have permitted an improved channel design, with a more gently sloping batter and stressed the need for lime stabilization, topsoiling, and immediate revegetation to minimize the possibility of tunnel development.

Performance study of asphalt road pavement with bituminous-stabilized-sand bases

Abstract: The possibility of using the windblown sands that occur in the northern areas of South West Africa for the construction of all-weather roads to carry heavy truck traffic has been investigated. Laboratory investigations and field trials in Pretoria, South Africa, showed that bituminous stabilization of these sands was promising, and a full-scale road experiment to test a limited number of bases of bituminous-stabilized sand was constructed in the homeland of Owambo, South West Africa. This paper describes the laying of the experiment and the construction techniques and control measures used. A new technique that establishes the optimum time for the compaction of a cutback bituminous-stabilized sand mixture after aeration by using a vane shear apparatus is described. The vane shear apparatus was also used to measure the in situ shear strengths of the various experimental bituminous-stabilized sand bases after compaction and during service; the results of these measurements, together with performance data after 8 years service with respect to deformation and cracking, are discussed. Laboratory and field studies are described and predictions about the performance of a bituminous-stabilized sand base under varying traffic conditions are made by using the best known techniques available at this time.

Mechanical behaviour of membranes in road foundations

Abstract: Two different situations, in which membranes can be applied in road construction, are considered. Firstly, the improvement of the stability of embankments, for instance for motorways, is dealt with. Secondly, a method to investigate membranes underneath thin road foundations, for instance for temporary roads, is developed.

Contribution to the engineering soil classification of cohesionless soils

Abstract: : This report is a state-of-the-art examination of existing soil classification systems with emphasis on classification of cohesionless soils. The purpose of the report is to note and suggest possible improvements to the Unified Soil Classification System currently used by the Corps of Engineers. Characteristics of soil types pertaining to roads and airfields and soil stabilization' are also considered. Criteria for differentiating between coarse-grained soil groups which have diverse engineering properties, but which are not fully described in other classification systems, are also proposed. Boundaries between clean gravels or sands, gravels or sands with some fines, gravels or sands with fines, and fine-grained soils are suggested as 5, 20, and 50 percent fines, respectively. Coarse-grained soils are also classified with respect to their coefficient of uniformity and coefficient of curvature as well graded and poorly graded, with the poorly graded further separated into narrow (i. e. uniform) and gap gradations. Criteria to separate each group are presented.

Pavement design for swelling soils: a review

Abstract: A literature review was conducted for the purpose of determining the most reasonable procedure for the design of airport pavements on expansive clay subgrades. Specific study areas were identification/classification systems, prediction of heave, setting acceptable levels of heave, and the design of stabilized soil layers. The effects of layer thickness, water table depth, initial load and suction, final load and suction, soil structure, seasonal variations and soil volume change behavior were considered. An attempt was made to establish tolerable levels of subgrade heave from the literature.

Crawford-south: colorado's first full length lime stabilization project

Abstract: Eleven years of evaluation since construction with lime tilled subgrade soils in place of aggregate subbase indicate that lime stabilization can be substituted for standard subbase materials. The few small failures which have occurred are attributed to poor drainage. Lime was spread on the scarified subgrade directly from the transport using a homemade spreader. Mixing was accomplished with a Bros mixer towed behind a medium size tractor. Initial mixing into the soil was done immediately after the dry lime had been spread and enough water added to bring the soil up to at least optimum. Further details of construction are described, as well as the soil conditions, cost and evaluation. The amount of the lime used for stabilizing the soil was determined by unconfined compressive strength tests. The soils tested did not show a great increase in compressive strength upon the addition of lime. Approximately 150,000 equivalent 18k axle loads have been sustained by this roadway in the last 11 years.

Chemical and vegetative stabilization of soils: laboratory and field investigations of new materials and methods for soil stabilization and erosion control

Abstract: A study was conducted on various chemical and vegetative methods of soil stabilization for possible use in the USBR's construction and O&M programs. This report summarizes three main items of work accomplished under the study: (1) Section A. Laboratory Studies. - (a) Results of screening tests conducted on 30 liquid soil stabilizing materials. Based on the results of these tests, tentative performance requirements were developed for water-based soil stabilizers. (b) Special studies conducted on materials and methods to waterproof problem soils, to arrest erosion occurring on slopes, and to bind gravel together for riprap applications. (2) Section B. Field Applications. - Discussions on where various chemical and vegetative methods have been used in new construction, rehabilitation, or O&M work. (3) Section C. State-of-the-Art Survey. - A survey on chemical stabilization of soils, and revegetation methods and materials for erosion control. Results of this study indicate that through chemical and vegetative stabilization of disturbed soils, sediment production can be reduced, fertile top soil preserved, and a more environmentally acceptable condition achieved after construction is completed.

Evaluation of sulfate-bearing waste material from fluidized bed combustion of coals for soil stabilization. Final report

Abstract: The effects of spent bed material from the fluidized bed combustion of coal in the physical and strength properties of selected fine-grained soils has been evaluated The spent bed material is a mixture of lime and calcium sulfate (together with some fly ash) obtained from a process being evaluated by the Energy Research and Development Administration in which pulverized coal is burned in a fluid bed of finely ground calcitic or dolomitic limestone Results of the study indicate that spent bed material is an excellent substitute for lime for soil stabilization The material behaves as a mixture of lime, calcium sulfate, and fly ash towards development of unconfined compression strength when mixed with soils It has been concluded that use of spent bed material for soil stabilization is a viable alternative to disposal when full-scale fluidized bed coal combustion plants become a reality

Development of soil stabilization guidelines for alabama soils

Abstract: A comprehensive sampling program of forty-seven surficial Alabama soils was conducted to develop state-wide lime stabilization guidelines. The selected soils were mixed with six percent hydrated lime, compacted into Harvard miniature-sized specimens, cured in a sealed condition for forty-eight hours at 120 deg. F, and tested to determine their unconfined compressive strength of Harvard miniature soil specimens prepared in an identical manner with the exception that hydrated lime was not added. The lime reactivity of the soil was determined using the Thompson criteria that the unconfined compressive strength difference between the lime-treated and untreated soils must be greater than or equal to fifty psi. A statistical "t" test of hypothesis was used to estimate the reliability of the results. A color-coded lime-reactivity state surficial soils map was prepared to assist civil engineers in assessing soil stabilization alternatives. /Author/