3D Numerical Analysis Of A Shallow Tunnel Face Reinforced By Longitudinal Pipes

Supporting tunnel face by Fiber glass pipes technology is an effective method to maintain the stability of tunnel face, thus reducing surface settlements, face deformation and maintaining the safety of the workers and the mechanisms used in tunneling. This paper presents the results of finite-difference numerical analyses (FLAC3D program) on the behavior of a shallow tunnel face reinforced by longitudinal fiber glass pipes. A 3D numerical model has been calibrated and used to demonstrate the effectiveness of this technique, and perform a parametric study to determine the critical reinforcements parameters (the density (number of pipes)(A) and length (L)). The results indicate that the face reinforcement technique using longitudinal fiber glass pipes can significantly reduce the movements (face displacement and surface settlements), and thus improving the face stability. These movements decrease by increasing the length of the pipes and increasing the density of the pipes until reaching the critical density, and when we reach the critical length, the pipes must be renewed to maintain the stability of the tunneling process.

Comparative practical study to the effect of the industrial additives on the concrete strength

There are various types of industrial fibers such as: (polypropylene fiber, fiberglass, silica fume powder, etc..). These fibers are used widely as additives for improving concrete strength. We study in our research the effect of each of polypropylene fibers, steel fibers, and silica fume powder, on two kinds of concrete mix the first ordinary mix and the second is mix other with Mazar sand. We found after the studying of mechanical properties for those mixes that a slight improvement on tensile strength of concrete has occurred, an increasing of compression strength of concrete has happened, and the failure style has changed according to the type of additive compared with concrete without additive.

دراسة بعض الخواص الطيفية و الميكانيكية لمزيج عديدي التكاثف بولي إيبوكسي + بولي فينوكسي

اهتمت هذه الدراسة بتطوير صناعة مواد بوليميرية جديدة، و نظراً للأهمية الكبيـرة لعديـد التكـاثف البولي إيبوكسي، قمنا بدراسة قساوته عندما يكون نقياً، و من ثم شكّلنا خلائط منه مع عديد تكاثف آخـر هو البولي فينوكسي بنسب محددة مختلفة، كما قمنا بتشكيل صفائح كومبوزيت من الخلائط السابقة مـع ألياف الزجاج تارة و الألياف الصخرية تارة أخرى و حددنا قساوتها. رافقت دراسة القساوة للعينات السابقة، دراسة لأطيافها ما تحت الحمراء و ذلـك لمقارنـة التركيـب بالقساوة، هذا و نوقشت تطبيقات هذه المادة في الحياة العملية أيضاً.