In this work we present a methodology to develop a surface and bulk TCAD radiation damage effects model which enables a predictive insight into the electrical behavior of novel solid-state detectors up to the particle fluences expected at the end of HL-LHC. To better understand, in a comprehensive framework, the complex and articulated phenomena related to the radiation damage mechanisms several TCAD simulations have been carried out and compared with measurements performed on test structures and sensors. Surface radiation damage effects have been deeply investigated on both p-type and n-type substrate test structures exposed to X-ray irradiation at doses in the range 0.05-100 Mrad(SiO2). The complete bulk and surface radiation damage model findings have been then compared with available measurements in terms of charge collection efficiency up to 2.0×1016 1 MeV equivalent neq/cm2.