【作者】 黄向京；

【导师】 杨果林；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2010， 博士

【摘要】 双绞合六边形钢丝网作为一种新型加筋材料,2005年以来广泛应用于国内水利、公路、铁路、市政等行业的各类加筋支挡结构中,取得了良好的经济、社会和环境效益。近30年来美国、意大利、泰国等学者开展了一系列研究工作,但双绞合六边形钢丝网作为加筋材料的加筋机理、筋土界面特性、动力响应等关键问题的研究较少或尚未涉及,国内的研究更是空白。双绞合六边形钢丝网加筋土挡墙的理论研究远滞后于工程实践。本文在湖南省交通科技项目“高速公路新型加筋土结构技术研究与示范工程”(200612)的资助下,以湖南省湘潭至衡阳西线高速公路加筋土挡墙工程为依托,对双绞合六边形钢丝网进行了筋材拉伸试验、拉拔试验、加筋红砂岩粗粒土挡墙的承载力模型试验、疲劳特性模型试验、水平抗震性能模型试验以及大量现场试验,采用理论分析、室内外试验和数值分析相结合的方法,对双绞合六边形钢丝网加筋土挡墙的计算理论和设计方法进行了系统研究,取得了如下创新性成果：1.通过不同法向压力作用下的拉拔试验,研究了双绞合六边形钢丝网与红砂岩粗粒土的界面特性,提出了基于剪切刚度的筋—土界面关系幂函数模型,修正了FLAC3D中Geogrid单元的界面关系,为工程设计提供了相关参数。2.通过不同含水量(14%、17%、饱和)和不同加筋层数(不加筋、加筋2层、加筋3层)的粗粒土三轴试验,分析了加筋双绞合六边形钢丝网对红砂岩粗粒土抗剪强度的影响、含水量对加筋效果的影响,系统研究了双绞合六边形钢丝网的加筋机理,建立了加筋土弹性非线性本构方程。3.系统研究了双绞合六边形钢丝网加筋土挡墙稳定特性。在原型试验基础上,采用FLAC3D对影响潜在破裂面形状和位置的相关因素进行了模拟分析,提出了适用于工程设计的双绞合六边形钢丝网加筋挡墙的改进双折线内部破裂面,推导了相应的稳定计算公式。4.提出了适合任意土质、任意墙背倾角、任意填料倾斜面的加筋土挡墙墙背主动土压力非线性分布的通用公式,提高了计算精度,满足了工程设计需要。5.通过双绞合六边形钢丝网加筋红砂岩粗粒土挡墙的承载力模型试验、疲劳特性模型试验和水平抗震性能模型试验,研究了双绞合六边形钢丝网加筋土挡墙在复杂动力作用下的结构特性。6.针对国内加筋土挡墙工程设计的现状,提出了基于极限平衡理论、可靠性分析和数值分析的双绞合六边形钢丝网加筋土挡墙的计算与设计方法,研究了地震荷载作用、膨胀土填料的加筋土挡墙设计方法,并成功应用于实际工程。7.为优化工程设计,降低工程造价,提出了双绞合六边形钢丝网+土工格栅复合加筋挡墙的结构模式。通过模型试验和数值分析,研究了复合加筋挡墙的结构特性。8.通过数值模拟对均匀加筋、分组加筋、交替加筋、混合加筋等多种复合加筋方式进行了深入的研究,提出了最优加筋方式。9.在湖南省湘潭至衡阳西线高速公路第12合同段K124+340-K124+895成功修建了我国第一座高速公路加筋格宾挡土墙,并进行了双绞合六边形钢丝网加筋土挡墙的现场试验,研究了挡墙内竖向土压力、水平土压力、筋材拉力及墙面变形随施工过程的变化及分布特征。更多还原

【Abstract】 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.更多还原