Study On Impact Response Characteristics Of Polyurea-coated Masonry Walls

Brick masonry wall has good performance of bearing,heat preservation and sound insulation,which is widely used in industrial and civil buildings.Typically,it is a kind of brittle structure.Under the explosion load,the wall is broken and forms a large number of flying debris,which poses a huge threat to the indoor personnel and property.In order to solve this problem,researchers in the field of safety protection put forward a method of adding new materials on the surface of the brick masonry wall to improve the anti explosion performance of the structure.The spray polyurea elastomer(SPUA)is favored by researchers because of its good mechanical properties and mature spraying technology.In order to study the anti explosion performance of brick masonry walls strengthened by polyurea elastomer,the common brick masonry walls with thickness of 365mm(wall 37)and 240mm(wall 24)are taken as the base in this paper.By the combination of theoretical calculation,numerical simulation and experimental verification,the failure phenomenon and response parameters of the unreinforced and reinforced brick masonry wall are studied.(1)According to the theoretical calculation method of wall structure response under the action of contact explosion,the critical penetration charges of wall 37 and wall 24 under the action of contact explosion are calculated to be 1.19 kg and 0.19 kg respectively.At the same time,the diameter of the explosion crater of the wall structure under different intensity contact explosion is analyzed.(2)By the combination of theoretical calculation,numerical simulation and experimental verification,the failure phenomenon and failure response parameters of brick masonry wall under contact explosion are analyzed.The failure limit,failure mode and failure mechanism of unreinforced walls under different intensity loads are studied.When the amount of contact explosive is small,the failure mode of the brick masonry wall is mainly reflected in the formation of the central explosion pit,the through hole and the horizontal and vertical cross cracks.When the amount of contact explosive is large,the damage to the masonry wall gradually spreads to the surrounding mortar joints,especially the surrounding mortar joints.At the same time,the spallation and collapse of the back blasting surface also increase significantly.The energy of the explosion load is released by splashing the wall fragments,deflection and moving the wall.(3)Using the method of numerical simulation and experimental verification,the failure phenomenon and failure response parameters of brick masonry walls strengthened by spray polyurea under contact explosion were analyzed.The failure mode and mechanism of the wall strengthened by different polyurea spraying methods under the contact explosion are studied.The results show that the reinforcement of brick masonry wall with double-sided SPUA can improve the support and integrity of the wall effectively,thus to a certain extent,it can resist the damage caused by contact explosion load,and can inhibit the damage of flying debris to the surrounding personnel and equipment.But simply increasing the thickness of the polyurea layer on the back surface cannot achieve a significant increase in the anti explosion effect.For wall 37,when the thickness of the polyurea layer on the front surface is 6mm,the thickness of the reinforcement on the back surface is 2mm;for wall 24,when the thickness of the polyurea layer on the front surface is 6mm,the thickness of the reinforcement on the back surface is4 mm.