In this paper, we address the problem of routing, space and spectrum assignment (RSSA) in survivable flex-grid networks that implement spatial division multiplexing (SDM). In our consideration, we focus on two switching policies for the SDM (namely, independent and joint) while the network survivability is provided by dedicated path protection (DPP). We formulate the problem (RSSA-DPP) as an integer linear programming (ILP) and we provide two solution algorithms including column generation (CG)-based method. Then, we perform simulations focused on the evaluation of the CG performance and analysis of the spectrum usage in survivable and flex-grid SDM networks. The results show that the proposed CG is a promising approach that outperforms reference heuristic. The CG method works especially efficiently for joint switching policy (average gap to optimal result was at most 2.2%). Moreover, the results show that SDM architecture can provide significant spectrum savings whose amount depends mostly on the applied switching policy.