THE COMBINED EFFECTS OF SOIL, WATER AND SURCHARGE LOADS ON THE STRUCTURAL BEHAVIOURS OF CANTILEVER RETAINING WALL

Abstract

Retaining walls are engineering structures constructed to resist lateral forces imposed by soil movement and water pressure; they are used as protection against the erosive forces of water and as a method of slope stabilization along highways, railroads and construction sites. This Study modeled the combined effects of soil, Surcharge loads and Hydrostatic pressure on the structural behaviours of cantilever retaining wall under varying geometric conditions. The limit state requirements for overturning, sliding and bearing pressure were studied under different geometric properties. The use of computer programming (Java) was employed for quick analyses of the conditions. This research therefore minimized the stress associated with the iterative process of design and analyses of these structures. The deductions gave range of satisfactory dimensions with respect to the height of the wall for the preliminary dimensioning state of design. This study also answered the remained unanswered question of the effects of an increasing load being supported by retaining wall. The results revealed that Cantilever retaining wall will perform satisfactorily based on the factors of safety of and as against sliding and overturning respectively if soil is ignored in front of the wall with following values of Base width: For wall supporting full submerged soil, the Base width, ; wall supporting submerge soil up to 0.6 of its Height, Base width,   and for wall with submerge soil up to 0.2 of wall height, Base width, . Results also showed that safety factors against sliding and overturning increase at a decreasing rate with constant decrease in water level. This gives an indication that water level greatly affects the stability of the retaining wall, that is, the higher the water level the greater the sliding and overturning effects. Results also revealed that sliding safety factor increases constantly with Base width while factor of safety against overturning increases at an increasing rate. This also shows the severity of sliding as against overturning. Both safety factors also increase at a decreasing rate with Wall height giving an indication that the stability of cantilever retaining wall increases with its Height under the same load. For an increasing surcharge values, sliding safety factor decreases constantly while overturning decreases at a decreasing rate. This also explains why overturning is less critical as compared to sliding effect.