1887

oa Civil Engineer in South Africa - Prediction of collapse settlement of a high embankment : technical paper

 

Abstract

The prediction of collapse settlement of soil masses has long been a problematic subject, especially in Southern Africa where the engineer often has to contend with compaction of soil structures in large tracts of semi-arid and arid land and where transported and residual soils with a collapsing grain structure are commonly encountered. The behaviour of soil structures, such as embankment dams or high fills, may be extremely complex to analyse when undergoing collapse settlement. In recent years computational methods for calculating the stresses and strains have improved markedly. This paper serves to illustrate a method for calculating collapse settlement of soil masses with arbitrary geometrical configuration and boundary conditions and where the stress is not constant during strain. An example is discussed of a high road embankment that is currently manifesting collapse settlement in the form of vertical and horizontal displacements. The fill was constructed during a dry period and since completion has been periodically inundated by heavy rains. The method of calculation involves nonlinear stress-strain and volume change parameters determined from conventional triaxial tests. The test methods and analyses are shown to be simple and inexpensive and applicable to most geotechnical structures.

Die voorspelling van swigversakking van grondmassas is lank reeds 'n problematiese onderwerp, veral in Suider-Afrika waar die ingenieur dikwels te doene kry met verdigting van grondstrukture in groot dele van die land wat semi-dor en dor is en ook waar vewoerde en residuele gronde met 'n swigstruktuur algemeen voorkom. Die gedrag van 'n grondstruktuur, soos byvoorbeeld 'n damwal of 'n hoë opvulling, kan besonder ingewikkeld wees om te analiseer wanneer dit swigversakking ondergaan. In die onlangse verlede het analitiese metodes om spannings en verplasings te bereken, aanmerklik verbeter. Hierdie referaat illustreer 'n metode om swigversakking te bereken van grondstrukture met arbitrêre geometriese vorms en randvoorwaardes en waarin die spannings nie konstant bly gedurende vervorming nie. 'n Voorbeeld word beskryf van 'n hoë padopvulling wet tans swigversakking manifesteer in die vorm van vertikale en horisontale verplasings. Die opvullings is tydens 'n droë periode gebou en is sedertdien periodiek deur swaar reënbuie deurweek. Die metode van berekening behels nie-liniêre spanningvervorming- en volumeveranderingparameters afgelei van konvensionele drie-assige toetse. In die referaat word getoon dat die toets- en analitiese metodes eenvoudig en goedkoop en toepasbaar op byna alle geotegniese strukture is.

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/content/civeng1/29/2/EJC25020
1987-02-01
2016-12-06
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