A hydraulic fracturing system that includes a fixed-speed gas turbine assembly having a gas generator and power turbine, both mounted to a semi-trailer. The system further includes a hydraulic pump mounted to the semi-trailer and connected to an output shaft of the power turbine and a hydraulically-driven fracturing fluid pump mounted to the semi-trailer and being in fluid communication with the hydraulic pump, the hydraulic pump supplying fluid pressure to the hydraulically-driven fracturing fluid pump. The system is configured such that the hydraulically-driven fracturing fluid pump receives fracturing fluid containing chemicals and proppants and pressurizes the fracturing fluid to a pressure sufficient for injection into a wellbore to support a hydraulic fracturing operation.