根据《地处规》第4.2.2条

$b=2.6m,\quad z=1.5m,\quad\frac{z}{b}=\frac{1.5}{2.6}=0.58>0.5$ ，查表4.2.2 $\theta=30^{\circ}$

$$ p _ {\mathrm{z}} = \frac {b l \left(p _ {\mathrm{k}} - p _ {\mathrm{c}}\right)}{(b + 2 z \tan \theta) (l + 2 z \tan \theta)} = \frac {2 . 6 ^ {2} \times 1 1 0}{(2 . 6 + 2 \times 1 . 5 \tan 3 0 ^ {\circ}) ^ {2}} = 3 9. 6 \mathrm{kPa} $$

$$ p _ {\mathrm{cz}} = 1. 5 \times 1 6 + 1 7 \times 1. 5 = 4 9. 5 \mathrm{kPa} $$

$$ p _ {\mathrm{z}} + p _ {\mathrm{cz}} = 3 9. 6 + 4 9. 5 = 8 9. 1 \mathrm{kPa} $$

因此选（C）