Análisis Comparativo De Sistemas De Contención Con El Uso De Modelos A Escala Reducida

EVALUATION OF THREE RETAINING SYSTEMS IN A MODEL TO REDUCED SCALE AS SOLUTIONS TO AN UNSTEADY SLOPE



Benarroch B., Abraham. MD


Professor of the Metropolitan University.Caracas, Venezuela.


Professor of the National University of the Armed Forces.Caracas, Venezuela.



Gioia V., Carmelo


Professor of the Technological University Institute.Capital Region, Venezuela.ABSTRACT : The work summarized in this article shows the influence that stabilizing solutions, well-known as Earth Reinforced, Discontinuous Sheet Piling and Nailing techniques, have on the safety factor, assuming invariable geometrical and geotechnical conditions.




INTRODUCTION


There are several techniques applied as corrective measures for controlling inestability of slopes.These are not always selected through a rigorous feasibility study in order to apply them, considering particular conditions of every work and in terms of the economic resources of the project in hand.
The full knowledge on the magnitude of the influence that these correctives (Earth Reinforced, Sheet Piling and Nailing) have on the stability condition of a particular slope, is the suitable way tomeet the best solution to a relationship cost-benefit.
In the case of Sheet Piling, an interesting relationship was observed from the tests, indicating the increment of the safety factor of a slope in direct relation to the fraction of the not retained pressure in the screen.


DESCRIPTION OF THE MODEL




An earth bank, fifteen (15) meters high and 90° degrees slope, with controlled andpreviously established variables was carried out experimentally as shown in Table 1. The Objective: To evaluate in a quantitative way, controlling deformations in the face of the bank and leveling in control points, the effect that three retaining and inclusion systems have on the initial safety factor of a bank of an unsteady condition.


To carry out the experimental tests, a rectangularmetallic box was used (high: 1.50 m.; wide: 0.75 m.; depth: 1.20 m.), which was built according to the result of the deformation analysis that set thickness and type of appropriate steel to be used. As structural part of the box, a frame gantry was annexed to measure reaction of loads to which terrain would be subjected during the tests. The walls were design flat and of minimum friction to avoidrestriction to slip because of existing confining.
Two soils were used. A Clayey sand (SC), half density, 60 cm. thick and a low consistency, Silty sand (SM) 90 cm. thick as a superior stratum. The characteristics of the soils and results of the tests (unitary weigh, grain, humidity percentage, compacting and direct-shear) are shown in the Table 1.
The instrumentation of the model was designedto measure pressures on the bank, deformations in the front face and physical variations of model during the tests. For that, six fleximeters of appropriate characteristics were used and placed in two lines. A first line was located 60 cm. below the crown of the bank and identified as A, B and C from left to right. And a second line located to a third of the height of the bank, it is 50 cm. fromthe bottom and identified as D, E and F from left to right. Also, a glycerin precision gauge and leveling devices were used.
Application of load on the crown of the bank was carried out using a square area plate (30 cm x 30 cm) on which a calibrated hydraulic jack was placed to perform gradual measuring of preset pressure with controlled increments on the frame gantry. The separation between theplate and the crown of the bank was set up after analyzing the effect of the lateral pressure that load would produce on the face of the bank in its vertical development.





Slope Without Corrective To Reduced Scale


Once the two soils were place with a standard compacting for the tests to be carried out, the load plate was placed at the appropriate position and leveling. The...