Engineering and soil

يمكنك مراجعة المقال الأصلي باللغة الإنجليزية هنا المهندس هاني عازر, أفريقي صاحب موهبة هندسية صلبة ومصمم واحدة من أحدث محطات القطار وأعلاها تكلفة والتي تصل ل 700 مليون يورو. وقد افتتح البناء - الذي التهم حوالي 500000 سم مكعب من الخرسانة و 58 طن من الحديد - لأول مره أمام الجمهور في السادس والعشرين من مايو 2006 هذه المحطة هي المحطة المركزية الجديدة ل برلين بداخلها: 54 سلم متحرك , 43 مصعد , مركز تسوق بمساحة أكبر من 15000 متر مربع , و42000 متر مربع من المكاتب موزعة على 3 طوابق كما توفر المحطة الآن 900 وظيفة لسكان برلين القادمين من مختلف الثقافات. سقف المحطة الجديد مصنوع من الزجاج الشفاف مانحاً منظراً رائعاً ل برلين يشمل الرايخستانغ الشهير. تستقبل المحطة بشكل يومي 164 قطار رحلات طويلة , 324 قطار إقليمي و 616 قطار محلي ومن المتوقع ان يصل عدد المستخدمين للمحطة إلى 300000 مسافر يومياً. في يوم تسليم المحطة, دُعي كبار الساسة الألمان ومجتمع المال والأعمال إلى برلين ليحضرو الافتتاح الرسمي بجانب المستشارة الألمانية أنجيلا ميركل ,وفي ظل الحماية المشددة قام المهندس هاني عازر بتس

Soils are formed by either physical disintegreation or chemical decomposition od rocks. Physical Distintegration. Physical disintegration or mechanical decomposition weatheringof rocks occurs due to the following physical processes : Temperature changes. Different minerals of a rock have different cofficint of thermal expansions. Unequal expansion and contractions of these minerals occure due to temperature changes. when the stresses induced due to such changes are repeated many times, the particles get detached from the rocks and the soils are formed. wedging action of ice. water in the pores and minute cracks of rocks gets frozen in very cold climates. As the volume of the ice formed is more than that of water, expansions occurs. Rocks get broken into pieces when large stresses develop in the cracks due to wedging action of the ice formed. spreading of roots of plants. As the roots of plants and shrubs grow in the cracks and fissures of the rocks, forces act on the rock.

A material is said to be permeable if it contains continuous voids. Since such voids are contained in all soils including the stiffest clays, and in practically all nonmetallic construction materials including sound granite and neat cement , all these materials are permeable. Furthermore, the flow of water through all of them obeys approximately the same laws. Hence the difference between the flow of the water through clean sand and through sound granite is merely one of degree. The permeability of soils has a decisive on the cost and the difficulty of many construction operations, such as the excavation of open cuts in water-bearing sand, or on the rate at which a soft clay stratum consolidates under the influence of the weight of a superimposed fill. Even the permeability of dense concrete or rock may have important practical implications, because water exerts a pressure on the porous material through which it percolates. This pressure, which is known as seepage pressure,

Darcy’s law The flow of free water through soil is governed by Darcy’s law. In 1856, Darcy demonstrated experimentally that for laminar flow in a homogeneous soil, the velocity of flow ( ) is given by, The velocity of flow is also known as the discharge velocity or the superficial velocity . Eq. 8.2 is known as Darcy’s law, which is one of the corner stones of soil engineering. The discharge is obtained by multiplying the velocity of flow ( ) by the total cross-sectional area of soil (A) normal to the direction of flow. The area A includes both the solids and the voids. The coefficient of permeability can be defined using Eq. 8.2 . If the hydraulic gradient is unity, the coefficient of permeability is equal to the velocity of flow. In other words, the coefficient of permeability is defined as the velocity of flow which would occur under unit hydraulic gradient. The coefficient of permeability has the dimensions of velocity [L/T]. it is measured i

Atterberg limit tests: they are designed to give an idea or index, how the soil will act under certain conditions. Bentonite clay has been added to increase the plasticity of the soil. LL test Liquid Limit is defined by the moisture content, in which a soil begins to act less as a viscous fluid and act more like a plastic putty. By convention: this is defined as the water content at which a groove cut into a soil pat the casagrande device requires 25 blows to close distance of 13mm PL test plastic limit is defined as the moisture content at which a material begins to act less like a plastic putty and more like a brutal solid. LL test procedure If the No. of blows falls between 15&20 : Scoop out some of the soil in place and one of the pre weight air cans and record the new weight for moisture content determination, place the can in the oven and reweight in 24 hours. If the No. of blows falls below 15 : Mix the soil to dry it out, clean &