Direct shear (shear box) tests were conducted on a moist, fi ne sand with D50 = 0.2 mm. The fines content (particles less than 0.075 mm) is less than 1%. The results of the tests are:
![1810_77f1aa6c-a831-4b9d-b4dd-a34770983c4a.png](https://secure.tutorsglobe.com/CMSImages/1810_77f1aa6c-a831-4b9d-b4dd-a34770983c4a.png)
(a) Plot the vertical load versus the horizontal load.
(b) Do the data align with a straight line through the origin? If not, explain why it is not so, assuming that the data are correct.
(c) Recommend the friction angle to be used for the foundation design of a 10-story-high building. Explain your recommendation.