The technique used in the case was "LOCKOUT".
In industry, a lockout is a transitory work stoppage (refusal of employing) in which the management of the company starts it while there is labor conflicts or debates. As it is described in the question, in this act, the employers decline the employee’s duty or maybe desire of working by not letting them get onto the company. It is completely different from a strike where the employees are the ones that decide not to work.
A lockout can be caused by the need of the employers to strengthen terms of employment to a group of employees.