【作者】 屈战辉；

【导师】 谢永利；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2011， 博士

【摘要】 土工格室柔性挡墙是一种新型的柔性支挡结构物,其能够满足恢复生态、绿化墙面和美化沿线景观的要求,具有广阔的应用前景。但是,其力学性状耦合了墙体及填土的共同作用,受力与变形性状复杂,墙体变形与土压力分布规律不明确,相关的设计及施工工艺还不完善,这些因素严重制约了该新型支挡结构物的工程应用。因此,开展柔性挡墙力学性状与设计方法方面的研究,对土工格室柔性挡墙的推广应用具有重大现实意义。此外,柔性挡墙土压力研究还具有重要的学术价值。论文围绕土工格室柔性挡墙的力学特性,从土工格室柔性挡墙的作用机理及变形特性分析入手,采用有限元仿真分析、离心模型试验、理论推导等多种手段,对土工格室柔性挡墙的土压力与墙体变形规律、参数变化对土压力及位移影响规律、土压力与位移计算方法和设计方法等方面进行了系统深入的研究,主要取得了以下5个方面的进展。1.采用数值仿真分析的方法对土工格室柔性挡墙的变形特性及土压力分布进行了系统研究,得出了土工格室柔性挡墙的变形特性及土压力分布规律。墙背土压力呈明显的非线性分布,从墙顶至墙底,土压力逐渐增大,在接近墙体中部某处存在拐点,拐点以下部分土压力急剧增大。在墙体中部存在水平位移分界点,分界点以上部分墙体位移模式接近平移,以下部分,墙体位移模式近似绕墙底的转动。墙体竖向位移同样呈现出明显的非线性。此外,还研究了墙体的高度、厚度、坡比、弹性模量、重度、粘聚力和内摩擦角等设计参数变化对土压力及位移的影响,给出了墙体设计参数改变对土压力及位移的影响规律。2.借助离心模型试验,通过不同结构形式的6组离心模型试验,对土工格室柔性挡墙墙体的水平变形和土压力分布规律进行研究。通过对比分析不同结构形式下墙体土压力及位移变化规律,找出了墙体鼓变点变化范围,验证了数值分析的结果。同时,研究成果也为土工格室柔性挡墙墙体土压力计算及设计方法的进一步研究提供了依据。3.对土工格室柔性挡墙主动土压力计算方法进行研究。针对土工格室柔性挡墙水平变位特征,将墙体的水平位移简化为平动和绕墙底转动的组合模式,提出了对应的土压力计算方法,并进行理论推导,给出了土压力计算公式。4.对土工格室柔性挡墙墙体位移计算方法进行研究。先将挡墙简化为悬臂梁,并将挡墙所受的力及边界条件转移到悬臂梁上,再根据悬臂梁的受力及边界条件对悬臂梁的挠曲及轴向压缩变形计算公式进行理论推导,给出了墙体位移计算公式。在给定参数的情况下,对墙体位移进行计算,并将计算结果同数值分析结果进行比较,两种方法计算结果在数值和分布形态方面均非常接近,验证了本文位移计算方法可行。5.基于本文提出的土压力及位移计算方法,提出了土工格室柔性挡墙的设计方法。结合工程实际情况,给出了柔性挡墙的结构形式及简化计算模型,并对墙顶部荷载简化计算方法进行探讨。综合考虑材料相互作用、墙体的稳定性、安全储备等方面的因素,提出了墙体最大变形不超过墙高5%的变形控制标准。以变形控制标准为前提,在本文土压力及位移计算方法的基础上,给出了确定挡墙相关参数的计算及验算方法,初步提出了柔性挡墙的设计方法。在计算的基础上,综合考虑施工因素及降水等不利条件后,给出了土工格室柔性挡墙墙厚设计建议值。这些成果在土工格室柔性挡墙的设计、施工及推广应用方面具有重要意义,提出的柔性挡墙土压力计算方法还具有一定的学术价值。更多还原

【Abstract】 Geocell flexible retaining wall is a new flexible retaining structure. It can meet the requirements of ecological restoration, greening the surface of wall and beautifying the landscape along the highway, and it will have broad application prospect. However, its mechanical behavior coupled with the common role of the wall and the filling soil, so the stress and deformation is complex. In addition, the related design and construction processes were imperfect. These factors severely hamper the engineering applications of the new retaining structure. Therefore, the research on the calculation of earth pressure and displacement has great practical significance for the designing and promoting the use of geocell flexible retaining wall. Moreover, the study on the earth pressure of flexible retaining wall also has important academic value.This paper focus on the mechanical properties of geocell flexible retaining wall, begining with the action mechanism and deformation characteristics of geocell flexible retaining wall, and combining with centrifuge mode test and finite element simulation analysis, a systematic study for mechanical characteristics and design methods of geocell flexible retaining wall has been carried out. Some new progress are made in following5aspects.LA systematic study for the defomation characteristics and earth pressure of geocell flexible retaining wall is done by using the numerical simulation method, and the law for defomation characteristics and earth pressure of geocell flexible retaining wall is obtained. The earth pressure of the wall is a clear non-linear distribution, and the earth pressure gradually increases from the top to the bottom of the wall, but, there is a turning point in the middle of the wall where the earth pressure of the following part increases dramatically. There is a dividing point in the middle of the wall, above the dividing point, the horizontal displacement is near to translation, and the other part can be approximated as rotation around the foot of the wall. Similarly, the vertical displacement of the wall shows obviously non-linear. Besides, the effect laws of the earth pressure and displacement from the change of the design parameters has been studied.2. Using centrifuge model test, through six different forms of structural model test, the horizontal deformation and earth pressure distribution of the geocell flexible retaining wall are studied. By comparing and analysing the laws of earth pressure and horizontal displacement from different structural forms of geocell flexible retaining wall, the changed range of the bulging deformation point has been found, and the numerical results for the geocell flexible retaining wall are verified. Meanwhile, the research results also provide the foundation for earth pressure calculation and design methods of geocell flexible retaining wall.3. The earth pressure theoretical calculation of geocell flexible retaining wall has been studied. Based on the horizontal deformation features of geocell flexible retaining wall, the horizontal displacement of the wall is simplified the translation model and the rotating model round the bottom of the wall. The author puts forward a corresponding calculation of earth pressure, and gives the calculating formula for earth stress by theoretical derivation.4. The displacement calculation method of the geocell flexible retaining wall has been study.Firstly, the retaining wall is simplified as cantilever, and the forces and boundary conditions of retaining wall is transfered to the cantilever. Then, in accordance with the force and boundary conditions of the cantilever, the theoretical derivation of the calculation formula for the deflection and Axial compression of the cantilever is presented. Finally, in accordance with the corresponding relationship between the cantilever and the retaining wall, the wall displacement formula is given.In the case of given parameters, the wall displacement is calculated and compared with the numerical calculation results.5. Based on the calculation methods of earth pressure and displacement, the design method of the geocell flexible retaining wall is proposed. Combined with the engineering practice, the author gives the structure forms and the simplified calculation model of the flexible wall, and discuses the simplified calculation method of load at the top of the wall. Considering the interaction between materials, wall stability, security reserves, and other factors, the wall deformation control standard that the maximum deformation does not exceed5%height of the wall is proposed. Based on the deformation control standard as well as the calculation methods of earth pressure and displacement in this paper, the calculation and checking methods for related parameters of the wall is given, and the initial proposed design method of flexible retaining wall is put forward. On the basis of the calculation, considering the construction factors and the adverse conditions of precipitation, the design suggestions value of wall thickness was given.These achievements have great significance for the design, construction and applications of the wall and the earth pressure calculation method for the flexible retaining wall also has important academic value.更多还原