Hydraulic Characteristics Of Building Solid Waste And Its Affect In Rainfall Induced Landslide

With the increasing scale of cities,how to deal with the consequent explosion of building solid waste has become the focus of attention.In order to save resources and reduce the burden of landfills,resource reuse has become a feasible means.At present,the disposal of building solid waste,especially concrete solid waste,mainly uses its strength as recycled aggregate.However,due to the structural damage in the process of disassembly,the strength of concrete using building solid waste as raw material is obviously lower,leading to the limitation in use.The hydraulic characteristics of the material are mainly determined by the internal pores.The hydraulic characteristics that meet the demand can be obtained by controlling the parameters such as particle size gradation and dry density,which are less affected by structural damage.However,there are few studies on the hydraulic characteristics of building solid waste,and the law of hydraulic characteristics has not been revealed.Rainfall is the most common cause of slope instability.How to prevent rainwater infiltration into the slope becomes the key to prevent and control rainfall-induced landslides.Previous studies have proved that capillary barrier system has anti-seepage performance.The application of building solid waste as cover material on slope can not only prevent rainwater infiltration,but also realize the reuse of building solid waste resources and achieve the purpose of waste treatment.However,there is no research on building solid waste as capillary barrier system material,and the effect of the cover on slope stability under rainfall conditions is not clear.In this paper,the recycled concrete aggregate(RCA)is divided into fine and coarse particles with the particle size of 2mm as the boundary.In order to study the influence of fine particle content on the hydraulic characteristics,the soil-water characteristic curve and the unsaturated permeability function of the concrete solid waste with different fine-grain content are measured by the pressure plate method combined with the simple evaporation method.A flume test is used to study the water migration of the capillary barrier system with construction solid waste as the material under rainfall conditions.In addition,the Seep/W and Slope/W modules of Geo-Studio software are used to study thestability of slope under continuous rainfall.It is found that the air entry value of RCA shows a typical growth curve with the increase of fine particle content.And when the content of fine particles is between 20% and 30%,the soil-water characteristic curve of RCA will have obvious bimodal phenomenon.In the slope covered by the capillary barrier system with building solid waste as material,when rainwater reaches the interface between the coarse-grained layer and the fine-grained layer,lateral diversion begins to appear,which can effectively prevent rainwater infiltration.The length of side guide row is linear with time.When RCA with 20% fine grains is used as coarse grained material,the infiltration on the surface of the slope decreases by about 80% compared with the original slope,and the safety factor is 0.17 larger.When the thickness of fine-grained layer is between 30 cm and 90 cm,the influence of overburden on slope safety factor is small,the maximum difference is 0.017.When the coarse-grained material is RCA with a fine particle content of 20% and the thickness of fine-grained layer is 30 cm,the critical rainfall time increases from4 days to 7 days compared with the original slope,and the maximum increase of safety factor is about 0.12 when the rainfall duration is 24 hours.