Research On Facing Wall Dynamic Response And Reinforcement Method Of Masonry Structure Under The Action Of Debris Flow

Masonry structure has a long construction history in our country.Because of its advantages of local materials,it is still widely used in rural areas,especially in mountainous areas.But masonry structure also has the weakness of low strength and poor integrity,so in recent years,some structural forms such as reticulated reinforced masonry have been developed to improve the seismic performance of masonry structure.However,in addition to the threat of earthquake disaster,houses in mountainous areas will also be threatened by debris flow.Most of the debris flow will impact the existing houses,resulting in the destruction of the facing wall of the houses.When the debris flow is large,even the whole houses will be buried.It is found that most of the house damage under the action of debris flow firstly occurs in the facing wall,and then causes the house collapse.Therefore,this paper studies the failure process and dynamic response on the facing wall under the action of debris flow,considers the fluid pressure of debris flow and the impact effect of stone inclusion,and puts forward the reinforcement method of steel mesh cement mortar plastering to improve the impact resistance of the facing wall and reduce the damage of the house caused by debris flow.The main research contents are as follows:(1)This paper summarizes the ground source,water source and specific landform of debris flow,what's more,discusses the research progress of relevant scholars in calculating the impact force of debris flow and the case of impact failure of debris flow on masonry structure.According to the failure characteristics and the mechanical properties of masonry structure,suggestions are put forward to improve the impact resistance of the facing wall,and the formula is used to explain in detail.(2)A typical two-story masonry structure house is selected as the research object.Because there are many solid materials carried in debris flow with different sizes and shapes,some solid materials with larger particle size can even reach 11 m,so the impact of stones will have a greater destructive effect on the facing wall.In this paper,five working conditions are set up to study the effects of debris flow fluid pressure,impact of mixed stones and continuous impact of mixed stones,and discuss the overall response of masonry structure after the impact of several solid substances on the facing walls in the process of debris flow impact.Through the analysis of structural stress,displacement of 10 observation points and time history of impact force,it is found that the continuous impact of solid materials is the most unfavorable to the structure,and the time interval of continuous impact has a greater impact on the damage and failure of the wall.(3)The discrete model of a single masonry wall is established to study the impact resistance of the wall.The parameters such as wall width,wall thickness,flow depth,velocity,stone shape and impact location are compared and analyzed one by one by using the control variable method.The collapse process of the on the facing wall under the impact of debris flow is analyzed.A series of the law of single masonry wall failure under the impact of debris flow are obtained.And the method of steel mesh mortar plastering is used to protect the facing wall under the impact of debris flow.The impact resistance of walls with different aspect ratio and the reinforcement effect of reinforcement method are studied.The main conclusions are as follows:For the facing wall with wall width of 3.48 M and 4.08 m,the anti debris flow impact performance after reinforcement is 41% and 40% higher than that of the same parameter wall without reinforcement,and the anti debris flow impact performance of the facing wall wall with wall width of 2.88 m is 13% higher than that of the comparison model.It shows that this method can effectively reinforce the wall with the aspect ratio ? 1 when the width of the wall is less than 4m.By this method,the debris flow can be confined to the outside,which can avoid the indoor silting and the continuous collapse of the structure caused by the destruction of the wall with the aspect ratio ? 1,and ensure the life and property safety of the indoor residents.