垫层底面自重应力p_cz=1.5×17+2.2×20=25.5+44=69.5kPa。条形基础：基底压力p_k=500/2.5=200kPa，基底附加压力p0=200-1.5×17=174.5kPa，扩散后附加应力p_z1=b(p0)/(b+2z tanθ)=2.5×174.5/(2.5+2×2.2×tan30°)=436.25/(2.5+2.54)=436.25/5.04=86.6kPa。圆形基础：面积A=π×1.5²=7.07m²，基底压力p_k=1400/7.07=198kPa，p0=198-25.5=172.5kPa，扩散后面积A'=π(d+2z tanθ)²/4=3.14×(3+2×2.2×0.577)²/4=3.14×(3+2.54)²/4=3.14×5.54²/4=3.14×30.69/4=24.1m²，p_z2=p0·A/A'=172.5×7.07/24.1=1219/24.1=50.6kPa。考虑应力叠加，条形基础与圆形基础扩散范围重叠，附加应力之和约86.6+50.6=137.2kPa，加自重69.5得206.7kPa，取205kPa。