Study On The Bearing Characteristics Of Reinforced Embankment With Scrap Tire Strips Embedded In TDA Composite Soil

With the increasing number of cars,scrap tires have increased dramatically.In order to reduce the land occupation and environmental hazards caused,reusing scrap tires has become a hot issue both at home and abroad nowadays.These days see the large-scale construction of transportation infrastructure in China,geogrid reinforcement is increasingly popular in a large number of high embankment,widening subgrade,weak subgrade and retaining structures.However,due to the limited resources of soils,fine-grained soils are often used as filler in the embankment,which cannot make full use of the reinforcing effect of geogrid.To solve this problem,many scholars have found scrap tire mesh strips have good interface properties and durability as reinforcing materials,and the ultimate pull-out force of mesh strips in coarse-grained soils was significantly higher than that in fine-grained soils.Therefore,this thesis proposes a method of using tire shreds from Tire-Derived Aggregate(TDA)mixed with soil as fillers and put scrap tire mesh strips inside it.This method can give full play to the shear strength of fillers and mobilize the interlocking effect of TDA and transverse members,and thus the pull-out capability of tire strips could be improved.To check the reliability of the new method and make a investigation on reinforcing effect and mechanism of composite reinforcement,this thesis conducted a systematic study on the shear behaviours of TDA-soil mixture,the pull-out characteristics of scrap tire reinforcement,the bearing capacity of the reinforced embankment and the influencing factors,by combining model tests and numerical analysis.The effect of different factors on the bearing capacity of reinforced embankment is discussed,which provides a theoretical basis and application value for the design and utilization of this method.Based on the research results,the following main conclusions are obtained:1.The TDA composite soil shear tests showed that the cohesion and internal friction angle increase with the increase of TDA content ranging from 0%to 30%.The pull-out tests showed that TDA has no significant effect on the interfacial properties of single tire strip at low TDA content.However,the peak pull-out force of the mesh tire strip is sensitive to TDA content and increase and then decrease with the increase of TDA content,with the optimal content of 20%.The end resistance of transverse members decreases nonlinearly from front to back,which leads to the establishment of the pull-out force equation for the scrap tire strips embedded in TDA composite soil.2.The bearing capacity tests show that the use of TDA,single strips and mesh strips can enlarge the bearing area and improve the bearing capacity of embankment,reduce whose vertical settlement and lateral displacement.Among them,10%content of TDA composite soil with mesh tire strips has the best reinforcing effect.Meanwhile,the external,internal and local stability of the embankment can be effectively improved by using TDA and tire strip composite reinforcement.3.Numerical analysis shows that the bearing capacity of the reinforced embankment is related to the thickness of TDA composite soil,the layers number and position of tire strips.It is found that the bearing capacity can increase more than 1.6 times by changing the thickness of TDA composite soil and the tire strips layers number.The embankment bearing capacity decreases with the increasing distance between TDA layers and slope top.Besides,the loading point location,soil strength and slope gradient also have different degrees of influence on the embankment bearing capacity,and the composite reinforcement can effectively compensate for the adverse effects of insufficient soil strength and steep slope gradient.