An exploratory drill hole was made in a stiff saturated clay having a moisture content of 38.9% and Gs = 2.34 as shown in the figure. The sand layer underlying the clay was observed to be under artesian pressure. Water in the drill hole rose to a height of 13.8 ft above the top of sand layer. If an open excavation is to be made in the clay, determine the (a) unit weight of the clay, and the (b) maximum cut before the bottom heaves

It is known that a particular deposit of clay has the following shear strength parameters: c' = 15 kPa, o' = 23°; Cu = 10 kPa, cu = 13° A sample of this clay is consolidated in a triaxial cell to an all-round pressure (03) of 250 kPa. The sample is then sheared by increasing 0₁, keeping 3 constant and the drainage valve closed. What is: i) ₁ at failure? ii) Pore water pressure inside the sample at failure? iii) Final values of 0₁' and 03'? iv) Value at failure of Skempton's pore pressure coefficient A?