Application And Research Of CFRP Prestressed Reinforced Earth Technology

Reinforced earth technology has been applied extensively to embankment design and construction at present. Considering the importance of embankment, the durability of the strip in reinforced earth has always been a crucial subject. Carbon fabrics reinforced plastics (CFRP), a new kind of material, is widely applied to civil engineering in recent years due to its characteristics such as noncorrosion, damping capacity, temperature resistance, lightweight, high strength and high modulus of elasticity. To our knowledge, no report of CFRP strip applied to reinforced earth has been found in domestic and the accounts abroad are few too till present. Based on the subject, "the new technique about restraining high embankment subside and increasing its stability ", from Traffic Bureau of Hunan Province, the adopting CFRP strip in reinforced earth, prestressing strip and anchoring to its end were proposed in this thesis in order to solve the problem. The subject was studied by experiments and theoretical analysis.The following five aspects of the new technology were studied by experimental means.1) Material experimental study. Through studying CFRP material, the CFRP strip was proposed and its mechanics parameters were measured; the physical parameters of clay and sand were measured through geotechnique test.2) Researching test piece performance. By triaxial test, the soil test piece reinforced by CFRP was studied. Through changing the quantity and number of layers of CFRP material, the strength laws of reinforced earth were studied. The concept of fictitious cohesive strength was put forward by test.3) Interaction study of strip and soil. The characteristic of strip friction in soil was acquired successfully. By direct shear test, the effect of strip direction and anchoring situation of strip end on shearing strength of the reinforced earth was carried out.4) Experimental study of the embankment model. The target of experiment is to compare the strength and deformation of three models, that is, model without strip, with strip and non-prestress, and with strip and prestress.5) The employment of the new technology to actual embankment. Actualmeasurements have illustrated that the technology could improve its modulus of elasticity and speed subside course notably.Two aspects of theoretical analysis and research were done in this work:1) Writing the program of finite element method (FEM). Three kinds of soil constitutive law, namely, Duncan-chang model, modified Cam-clay model, D-P model could be considered in this program. Boundary condition of subgrade was simulated by the infinite element. The program can imitate the constructing course. Using the program, two high embankments were analyzed and some meaningful conclusions were made.2) The slope stability of embankment employing the technology was studied. Simplifying calculation formula and a kind of accurate computing method were proposed. The accurate computing method can solve internal force of reinforced earth and tensile force of strip by FEM, then compute minimum safety coefficient and slip plane corresponding by genetic algorithm (GA). With the merit of fast speed and high efficiency, this kind of method could pioneer the way for arbitrary shape.