Components of Tunnel

Chainage The length along the longitudinal direction of tunnel Crown The top portion of tunnel is crown. It can be circular,semi-circular or rectangular in shape. Side/Wall The side portion of tunnel. It is generally vertical. Bench The bottom part of tunnel left after the excavation of heading is said to be bench. Excavation of face in done in multiple step for large cross sectional area. Invert The lower portion of tunnel Portal The entrance of tunnel is portal. Heavy support […]

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Difference between CPM and PERT Method in project management

CPM PERT CPM stands for critical path method PERT stands for program evaluation and review technique It is activity based method It is event based method It is used in repetitive works like construction It is used in non-repetitive works like research It is deterministic method with single time estimate It is probabilistic method with three time estimate namely optimistic, most probable and pessimistic It is concerned with control of cost and time It is only concerned with control of […]

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Snyder’s Unit Hydrograph

To Plot snyder’s unit hydrograph we need value of basin lag (tpr), time base(tb) , width of hydrograph at 50% discharge(W50) , width of hydrograph at 75% discharge(W75) The peak time is distance from centroid of effective rainfall to peak of the discharge. where, tp = Peaking time in standard condition tpr = Basin lag in general condition C1=0.75 Ct=Watershed factor where, qp is peak discharge per unit catchment area Cp=Watershed factor C2=2.75 C3=5.56 The width of hydrograph at 50% […]

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Dry weight of sand mortar

Mortar is heterogeneous mixture of cement sand and water. Water reacts chemically with cement ingredients resulting in hydration of cement and fills the voids between cement and sand. As water is added to dry cement sand mixture the volume reduced. For quantity estimate of cement sand mortar the wet mortar’s volume should be increased to account for Water required for hydration. Water required filling of voids. Dry weight of mortar = Wet weight of mortar * 1.33

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Geology of World – Continent – Africa

Africa is second largest continent. Africa covers 20.4 % of total world land area Africa is hottest continent. Africa is separated from Europe by Mediterranean sea. Africa is separated from Asia by Red Sea. Number of countries:55 Number of land-locked countries: 16 Highest mountain: Mt Kilimanjaro Biggest Country:Algeria Smallest Country: Seychelles Longest River: Nile Biggest Desert: Sahara Desert Biggest landlocked country:Chad

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Magnetic Dip and Magnetic Declination

Magnetic Dip The vertical angle between magnetic needle and earth surface is called angle of dip. Magnetic Dip at equator is 0 degree. Magnetic Dip at pole is 90 degree. Dip is positive if needle points towards the ground. Dip is negative if needle points away from the ground. Declination The horizontal angle between magnetic meridian and true meridian is called declination. Magnetic declination is positive towards east direction. Magnetic declination is negative towards west direction. Isogonic line The line […]

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Classification of Soil on the basis of mode of transportation

Soil is formed by disintegration of rocks. The disintegrated rock particles then get transported by different natural agents like wind , water, etc either to same place as origin of rock or towards new region. The transported soil then gets deposited and keeps on increasing in quantity. Natural events continue to occur , the soil deposited once again get eroded and process of erosion-transportation-deposition-upheaval keeps on repeating. Types of Soil on the basis of mode of transport Alluvial Soil Soil […]

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