Ka1=tan2(45-30/2)=0.333,√Ka1=0.5774
Ka2=tan2(45-20/2)=0.49,√Ka2=0.7
0~3m水土分算:
z01=2c/(γ√Ka1)=2*5.8/(10*0.5774)=2
e1=10*3*0.333-2*5.8*0.5774=3.3
pw1=10*3=30
3~6m水土合算:
e2=10*3*0.49-2*20*0.7=-13.3,小于零,需判断z02(从3m位置算起)
(10*3+20 *z02)*0.49-2*20*0.7=0,解得z02=1.357
即0~2m、3~4.357m主动土压力为零
e2=(20*3+20*3)*0.49-2*20*0.7=30.8
Ea=0.5*3.3*(3-2)+0.5*30*3+0.5*30.8*(3-1.357)=71.96