01.What are the functions of a column in a building?
Answer: A column is used to support the weight of the roof and/or the upper floors. Now days, many columns are used for decorative purposes. A column along with load bearing beams can support a lot of weight.
02. What is the function of packing materials in the joint of concrete pipes in pipe jacking?
Answer: Packing materials are about 10 mm to 20 mm thick and are normally made of plywood, fibreboard or other materials. In case packing materials are absent in pipe joints for pipe jacking, then any deflection in the joints reduces the contact area of the concrete and it leads to spalling of joints due to high stresses induced. With the insertion of packing material inside the pipe joints, the allowable deflection without damaging the joint during the pipe jacking process can be increased.
03. For drained reclamation, what is the significance of smear zone induced by installation of band drains?
Answer: During installation of band drains, smear zones are created in which zones of soil surrounding the band drains are disturbed. The compressibility of surrounding soils is increased and it results in the reduction of their permeability. In fact, the surrounding soils are remoulded during the installation process and the effectiveness of band drains is reduced. In essence, for the reduced permeability of soils around band drains, it takes longer time to complete the consolidation process.
04. What are the causes of building collapse?
Answer: The Passage of time is one reason. Buildings also collapse due to weak foundations. Earthquakes, hurricanes and other natural disasters can also damage the structure of the buildings and cause it to collapse. Bombings or demolition of buildings is also other reasons.
05. In selecting screw pumps in polder scheme projects, what are the factors that affect the design capacity of screw pumps?
Answer: The commonly used angles of inclination for screw pumps are 30°, 35° and 38°. For screw pumps of relatively high lifting head, like over 6.5 m, angle of inclination of 38° is normally used. However, for relatively lower head and
high discharge requirement, angle of inclination of 30° shall be selected. In general, for a given capacity and lifting head, the screw pump diameter is smaller and its length is longer for a screw pump of 30° inclination when compared with a screw pump of 38° inclination. To increase the discharge capacity of screw pumps, a larger number of flights should be selected. In fact, screw pumps with 2 flights are more economical that that with 3 flights in terms of efficiency and manufacturing cost. Moreover, the discharge capacity is also determined by the screw pump diameter and sizes of 300 mm to 5000 mm are available in current market.