Numerous　studies　have　shown　that　the　invasion　of　the　chemicals　plays　an　important　role　on　the　geomechanical　properties　of　the　soil.　This　article　aims　to　investigate　the　shear　behavior　of　contaminated　soil　by　laboratory　tests　and　develop　an　extended　shear　strength　model　on　the　basis　of　the　experimental　results.　In　order　to　explicitly　evaluate　the　effect　of　solution　concentration　on　the　shear　strength　behavior　of　soil,　the　remolded　samples　of　kaolinite　mixed　with　different　concentrations　of　CuCl2　solutions　were　prepared　to　carry　out　a　series　of　consolidated-undrained　triaxial　shear　strength　tests.　The　results　indicate　that　different　CuCl2　solution　concentrations　have　significant　influence　on　the　shear　strength　property　of　kaolinite.　With　the　increase　of　CuCl2　solution　concentration,　the　shear　strength　of　soil　displays　a　declining　tendency,　and　the　strength　properties　including　cohesion　and　internal　friction　angle　are　also　reduced,　which　indicates　the　Cu　(II)　that　existed　in　the　soil　samples　has　deteriorated　the　soil　strength　strongly.　Based　on　the　experimental　results,　an　extended　Mohr-Coulomb　strength　model　for　contaminated　soils　has　been　proposed　by　introducing　osmotic　suction　as　a　macro　variable　parameter.　The　conclusions　in　this　study　can　provide　reference　for　pollution　prevention　of　existing　and　future　foundations.