Not when the valve box is bottomless and all of the weight will be concentrated around the perimeter of this box. It would also be advisable to place a double layer of geotextile underlayment both directly under the liner and between the liner and the valve box. With a one piece basin, such as that earlier recommended, the weight is distributed over a large area, so the resulting psi is manageable. With what you are proposing the weight will be concentrated into an area that is actually smaller than the base of the water feature. Asking for problems.
"Everybody is ignorant, only on different subjects." - Will Rogers