Design Theory And Experimental Study On Reinforced Earth Retaining Wall With Double Twisted Hexagonal Wire Mesh

From 2005, as a kind of new type reinforced material, double twisted hexagonal steel wire mesh was used widely in reinforced retaining structures, including hydraulic, highway, railway and municipal engineering, obtained good effect. In the latest 30 years, scholars from the USA, Italian and Thailand made some researches about double twisted hexagonal steel wire mesh. But some key problems about this reinforcement such as its reinforcement mechanism, interface characteristics and dynamic response were studied merely, even none in China. The theoretical research lagged behind engineering practice.Supported by communicational science and technology foundation of Hunan province(200612), based on a project named west line of Xiangtan-Hengyang expressway, a series tests such as tensile test, pullout test, bearing capacity test, fatigue test, aseimatic test and field test have been done, calculation and design methods of retaining wall reinforced by double twisted hexagonal steel wire mesh have been studied systematically by combining theoretical and numerical analysis in this paper and some.innovative results have been gotten.1. Through a series of pullout tests under different normal pressures, the interface characteristic between double twisted hexagonal steel wire mesh and coarse-grained red sandstone soil has been studied. Power function model based on shear stiffness about interface relationship between reinforcement and soil has been proposed. The interface relationship between Geogrid unit and soil of FLAC3D has been modified, and provided parameters for engineering design.2. Through triaxial test of coarse-grained soil with different moisture contents(14%,17%,saturated)and different reinforcement layers(non-rein forcement, two layers, three layers), the influence of double twisted hexagonal steel wire mesh on coarse-grained red sandstone sample, moisture content on reinforcement effect and the development process of reinforcement effect have been analyzed. The reinforced mechanism of this wire mesh has been researched systematically. The elastic non-linear constitutive equation has been established. 3. Strength and stability characteristics of retaining wall reinforced by double twisted hexagonal steel wire mesh have been researched systematically. Based on prototype test, related factors about shape and position of fracture plane have been simulated by using FLAC3D, and the double broken line type internal fracture plane has been presented to suit for engineering design. The related stability computational formulas have been derived.4. Based on limit equilibrium method, general formulas have been deduced to predict the nonlinear distributed active earth pressure acting on back of reinforced retaining wall with any backfill, any inclination of back, as well as any single slope of filling surface. Calculation accuracy is improved to satisfy engineering design.5. Characteristics of earth rataining wall reinforced by double twisted hexagonal steel wire mesh under complex dynamic conditions have been studied by bearing capacity model test, fatigue model test and aseismatic model test.6. According to present situation of reinforced retaining wall in China, calculation and design method of retaining wall reinforced by double twisted hexagonal steel wire mesh have been put forward based on limit equilibrium method, reliability analysis, as well as numerical analysis. The design methods of which under aseismatic load and expesive soil filling have been put forward and used in engineering successfully.7. In order to optimize engineering design, to cut down construction cost, a compound reinforced retaining wall using both double twisted hexagonal steel wire mesh and geogrid has been designed. Its structural characteristics have been studied through model test and numerical analysis.8. Diffferent reinforcement pattens such as uniformed, grouped, alternating, mixed reinforcement have been studied thoroughly through numerical stimulation, and the optimal reinforcement manner has been proposed.9. In the section, K124+340-K124+895, of west line of Xiangtan-Hengyang highway, the first gabion reinforced retaining wall used in highway in China has been constructed. The distribution of vertical earth pressure, horizontal earth pressure, tensile strength of reinforcement, transformation of face as well as their change in the process of construction have been studied through field tests.