Modeling and Accelerated Testing of Cured-In-Place Plastic Sewer Rehabilitation Liners

就地固化塑料（CIPP）管道内衬最近被用于修复恶化的下水道管道。这种尾管通常安装在地下水位以下，因此受到外部压力的影响，这可能导致主管内的尾管发生蠕变引起的屈曲。对这种屈曲现象的理解不足被认为是技术的限制和更经济有效的下水道修复的障碍。为了解决这个问题，将进行实验和分析相结合的研究计划。实验项目将包括衬垫材料的室温和高温材料特性测试，以及衬垫在相同温度下的蠕变屈曲测试。随着温度的升高，这种材料的软化将被用来建立时间和温度之间的关系，以便在方便的时间尺度上进行的测试可以延长到几十年。分析程序将检查屈曲问题的封闭形式解，并将涉及大量的有限元素和尾管屈曲的统计建模。将评估尾管屈曲时间随外部压力和尾管/主管几何参数的统计变化，以确定尾管系统在预期设计寿命内存活的概率。该研究项目将为塑料下水道修复衬垫的长期测试建立一种新的方法，并将强调必须考虑的因素，以开发一个基于物理的模型来预测在50年以上的服务期内CIPP衬垫的弯曲

Cured-In-Place Plastic (CIPP) pipe liners have recently been employed to rehabilitate deteriorated sewer lines. Such liners are often installed below the water table and are consequently subjected to external pressure which may lead to creep-induced buckling of the liner within the host pipe. Insufficient understanding of this buckling phenomenon is regarded as a limitation of the technology and a barrier to more cost effective sewer rehabilitation. To address this problem, coupled experimental and analytical research programs will be undertaken. The experimental program will involve room temperature and elevated temperature material characterization tests of liner materials as well as creep-buckling tests of liners at these same temperatures. The softening of this material with increasing temperature will be used to establish a relationship between time and temperature such that tests performed on convenient time scales can be extended to decades. The analytical program will examine closed form solutions to the buckling problem and will involve an extensive amount of finite element and statistical modeling of liner buckling. The statistical variation of liner buckling times as a function of the external pressure and liner/host pipe geometry parameters will be assessed to determine the probability that a liner system will survive for the desired design life. This research program will establish a new methodology for the long-term testing of plastic sewer rehabilitation liners and will highlight the factors which must be considered to develop a physically based model to predict buckling of CIPP liners over a 50+ year service period.***