Observation

            However, some of them were not able to:
           
-           state the three causes of collapse of the sides of trench;

-           sketch a cross-section through a deep strip foundation instead they sketch
wide strip.

The expected response to question 1 is as given below:

  (a) 

(i)         general shear failure of the embarkment created by the trench side;

(ii)        effect of freezing and thawing on soil particles in embarkment created by
the trench;

(iii)       failure due to heavy loads being placed near the edge of the trench;

(iv)       variation in soil strata;

(v)        instability of earth materials in a made up ground which may be hidden
just behind the sides;
(vi)       collapse due to flooding of the trench;

(vii)      failure of timbering system used to support sides of the trench excavation;

(viii)     rainfall causing land slide.

(b)       

or