$2.$As shown in Figure $2,$ the lateral force V $=312$ kN is acting on the upper part of the reinforced concrete wall, and an additional compressive force P $=6,000$ kN is acting. As the compressive force P acts, the length of the non$-$cracking area at the bottom of the wall increased to $=1,665$ mm$.$ The average vertical force and average shear force acting on the stress element indicated in the non$-$cracking area of the bottom of the wall can be calculated as follows. $1)$ Use this to cut the mother circle $($STEP$1$ to draw with the mother circle$),2)$ Find the main field stress $,$ main compression stress $,$ and maximum shear force $.3)$ When the tensile strength of concrete is $1\mathrm{.}09$ MPa and the compressive strength is $30$ MPa, no failure will occur under the main stress state. If destruction is to occur, should the lateral force V be increased or decreased?