This　study　investigates　the　factors　affecting　crack　development　in　red　clay　roadbeds　and　slopes　through　a　combined　computational　and　experimental　approach.　A　finite-element　model　of　a　prefabricated　cracked　red　clay　fracture　was　established　using　a　cohesive　zone　model,　integrating　fracture　mechanics　theory　with　numerical　analysis.　The　model　was　based　on　an　improved　three-point　bending　test　system　to　obtain　raw　data.　The　effects　of　prefabricated　crack　depth,　width,　shape,　and　support　span　on　crack　propagation　in　red　clay　were　systematically　investigated.　The　results　indicate　that　the　reliability　of　the　model　is　confirmed　by　the　three-point　bending　test.　The　degree　of　curvature　of　the　crack　depth　on　the　Mode　I　fracture　extension　was　more　significant　compared　with　Mixed　mode　I-II　fractures.　Variations　in　prefabricated　cracks　fracture　had　minimal　impact　on　peak　load　and　the　degree　of　curvature　of　the　crack　extension　in　Mode　I.　The　maximum　crack　width　and　length　occurred　at　a　prefabricated　crack　width　of　2　mm,　with　the　lowest　curvature　observed.　Conversely,　a　crack　width　of　6.5　mm　led　to　the　highest　curvature　in　Mixed　mode　I-II　fractures.　The　alteration　of　the　prefabricated　crack　shapes　revealed　that,　for　Mode　I　fracture,　triangular　prefabricated　cracks　resulted　in　the　maximum　crack　width　and　length,　and　the　lowest　degree　of　crack　curvature.　The　shape　of　the　prefabricated　crack　had　a　minor　effect　on　peak　load,　with　triangular　tips　yielding　the　longest　crack　extension　length　and　highest　degree　of　curvature　in　Mixed　mode　I-II　fractures.　Support　span　had　a　limited　effect　on　the　crack　extension　path　of　Mode　I　fracture;　increasing　the　span　led　to　a　60.4%　reduction　in　maximum　crack　width　and　a　28.9%　reduction　in　maximum　crack　length.　In　Mixed　mode　I-II　fractures,　the　support　span　inversely　correlated　with　maximum　crack　width　and　length.