تقييم الهطول لخط صرف صحي (GRP) تحت طريق رئيسي

Evaluation of Deflection for Sewage Trunk Line (GRP) Embedded in Main Roads

      Design and analysis of buried infrastructure like buried pipe need efficient methodology is applicable in practice. In this research, a buried GRP pipe was evaluated under dead and live loadings. The (IOWA) equation and three-dimensional finite element simulation were carried out to examine structural behavior of the GRP pipe. The 3D-finite element analyses were performed using a software package called Plaxis-3D, 2014. Three types of soil (clay, sand and silt) and two pipe diameter size (1 and 1.4) m with a fixed pipe stiffness of (10000) N/m2 were investigated in the analysis. Additionally, various burial depths were considered in this work. The initial depth was 2 m, and then the depth was increased at 2 m interval in each case, until maximum depth of 12 m was achieved.

     Plaxis 3D comparison done to ensure results is conformed to field test. Same properties of soil and pipe as input in plaxis program and comparing with field test done by author. The results compare well with those collected from field measurements, whereas the margin of error was approximately (0.5) % as diameter deflection percent. This comparison step can be adapted to model all cases with Plaxis software. The results of (IOWA) formula showed that maximum deflection of 1.4 m pipe placed in a clay soil is 5.343%. This deflection value is considered unsafe according to the standard limit which is equal to(5)% of the results also indicated that maximum deflections were 3.674 % and 3.495% for the pipe founded in sand and silt soils, respectively. These deflections were determined at maximum depth 12 m. The granular soils (silt, sand) show more stability than clay soil. According to plaxis analyses clay soil was weakest material reach maximum deflection of 2.06 %, where sand reach 1.256 % and silt reach 0.9737 %.one more time granular soils prove more stability against loading condition.