Biaxial Response of Polymeric Structural Membranes

聚合物结构膜的双轴响应

• 批准号: 1635029
• 负责人: Steven Perkins
• 金额: $ 8.45万
• 依托单位: Montana State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635029&HistoricalAwards=false
• 关键词: Biaxial; Response; Polymeric; Structural; Membranes

Polymeric membranes, commonly referred to as geosynthetics, are used for in a number of Civil Engineering projects to reinforce soils. They are commonly used in retaining walls, constructed slopes, roadways, and reinforced granular load transfer platforms. Advanced methods for the analysis of existing and especially new applications involving reinforcement geosynthetics require information from load tests that duplicate the type of loads seen in field applications. Field applications typically involve the simultaneous application of load in two directions of the material. To date, laboratory testing techniques have not been sufficiently developed to apply these types of loads. Research performed under this project will involve the use of a biaxial loading frame to evaulate the biaxial loading response of an array of geosynthetic reinforcement materials. These data will allow for the development of advanced material models describing the mechanical response of geosynthetics subject to load in two directions. These models can be incorporated into advanced analysis methods for the types of applications noted above. This work can also lead to optimization of manufacturing techniques that lead to superior mechanical properties.Polymeric membranes or sheets, commonly referred to as geosynthetics, are used for structural reinforcement in a number of applications including retaining walls, constructed slopes, roadways, and reinforced granular load transfer platforms. In these applications, geosynthetics experience load simultaneously in each principal material direction. These types of loads influence the load-strain properties typically in beneficial ways as compared to material response observed in uniaxial loading. Load-strain properties of geosynthetics are typically determined from uniaxial tension tests on wide-width samples (ASTM, 2011 and 2015), which simulate plane strain loading. The free sides of the sample make this simulation poor, meaning the loading condition is somewhere between uniaxial loading and plane strain loading. This test is typically regarded as an index test. A more advanced test is needed to describe material behavior for loads expected in field applications. Numerical models are commonly used as research tools for the examination of new applications involving reinforcement geosynthetics and for the development of robust design methods. These models have not been calibrated against realistic field loadings. Design methods should use load-strain material properties pertinent to the type of field loading expected. An advanced test device is needed to calibrate these models. Biaxial testing devices apply loads simultaneously in each principal direction of the material and can duplicate the types of loads seen in field applications. Biaxial tests have been developed for materials used for fabric buildings and roofing systems (Beccarelli, 2015), however only limited studies have been performed on geosynthetics. Montana State University has recently built a load frame for biaxial loading of geosynthetics. This research will use this device to examine the biaxial response of an array of geosynthetics. These data are needed to examine the suitability of various numerical models for describing biaxial load response and for providing linear elastic material properties pertinent to field loading conditions. The broader impacts of this project include generating information that will impact industry, engineering practice and education by: i) promoting the use of a sustainable construction material, ii) providing a means of assessing material response leading to optimization of geosynthetic manufacturing processes, and iii) supporting a graduate student who will take ownership of the testing program. Geosynthetics are a sustainable construction material in that they reduce the use of natural resources, may be manufactured from recycled content, lend themselves to simple construction techniques, are cost effective, and offer a higher degree of and resiliency due to their compatibility with the ductile behavior of surrounding soil materials. Geosynthetics reduce the carbon footprint of construction by the reduced use of natural resources and reduced energy associated with resource extraction and transport and by increasing the life of the constructed facility, thereby reducing maintenance and replacement operations.

聚合物膜，通常被称为土工合成材料，用于许多土木工程项目，以加强土壤。 它们通常用于挡土墙、已建斜坡、道路和强化粒状荷载传递平台。 现有的，特别是新的应用，涉及加筋土工合成材料的分析的先进方法需要从负载测试，复制在现场应用中看到的负载类型的信息。 现场应用通常涉及在材料的两个方向上同时施加载荷。 到目前为止，实验室测试技术还没有得到充分发展，以应用这些类型的负载。 在本项目下进行的研究将涉及使用双轴加载框架来评估一系列土工合成加固材料的双轴加载响应。 这些数据将允许开发先进的材料模型，描述土工合成材料在两个方向上的负载的机械响应。 这些模型可以结合到上述应用类型的高级分析方法中。 这项工作也可以导致优化的制造技术，导致上级的机械性能。聚合物膜或片材，通常被称为土工合成材料，用于结构加固在许多应用，包括挡土墙，建设斜坡，道路，和加强颗粒负荷转移平台。 在这些应用中，土工合成材料在每个主要材料方向上同时承受载荷。 与单轴加载中观察到的材料响应相比，这些类型的载荷通常以有益的方式影响载荷-应变特性。 土工合成材料的载荷-应变特性通常通过对宽幅样品进行单轴拉伸试验（ASTM，2011和2015）来确定，该试验模拟平面应变载荷。 样品的自由侧使得该模拟较差，这意味着加载条件介于单轴加载和平面应变加载之间。 该测试通常被视为索引测试。需要更先进的测试来描述现场应用中预期载荷的材料行为。 数值模型通常被用作研究工具，用于检查涉及加筋土工合成材料的新应用和开发稳健的设计方法。这些模型尚未根据实际的现场载荷进行校准。 设计方法应使用与预期现场载荷类型相关的载荷-应变材料特性。 需要一种先进的测试设备来校准这些模型。 双轴测试设备在材料的每个主方向上同时施加载荷，并且可以复制现场应用中看到的载荷类型。 双轴测试已开发用于织物建筑和屋顶系统的材料（Beccarelli，2015），但对土工合成材料的研究有限。 蒙大拿州立大学最近建立了一个双向加载土工合成材料的负载框架。 本研究将使用此装置来检测一系列土工合成材料的双轴响应。需要这些数据来检查各种数值模型的适用性，以描述双轴载荷响应，并提供与现场载荷条件相关的线弹性材料特性。 该项目的更广泛影响包括产生将影响行业，工程实践和教育的信息：i）促进可持续建筑材料的使用，ii）提供评估材料响应的方法，从而优化土工合成材料制造工艺，以及iii）支持将拥有测试计划的研究生。 土工合成材料是一种可持续的建筑材料，因为它们减少了自然资源的使用，可以由回收的内容物制造，适合于简单的施工技术，具有成本效益，并且由于它们与周围土壤材料的延展性行为的相容性而提供更高程度的弹性和回弹性。 土工合成材料通过减少自然资源的使用和减少与资源开采和运输相关的能源，以及通过增加建造设施的寿命，从而减少维护和更换操作，减少建筑的碳足迹。