A double under$-$reamed pile $($shaft diameter $0\mathrm{.}5$m$,$ bulb diameter Im$.$ total depth $11$m$)$ is installed in a stratum of cohesive soil. The centre of the under$-$rearms are at depths of $8\mathrm{.}5$m and $10$ m respectively from the ground level. Evaluate the ultimate vertical compressive load on the pile. The undrained shear strength along the cylindrical portion is $60$ kPa, and the same around the under$-$resam is $100$ kPa and below the pile tip is $150$ kPa. The bulb is $65$ cm thick close to the stem and $15$ cm thick at the edges. Use the IS $2911($Part $3)2021$ method.