techazad

· What is weathering or rock? Weathering is a part of geological cycle. It consist of disintegration and decomposition of parent rock. Weathering action take place through physical and chemical agencies. Physical agencies break down the rock in to smaller particle size without chemical change. The various agencies responsible for weathering are:- 1.    Unequal expansion and contraction due to temperature change. 2.    The weeding action of growing root of trees. 3.    Abrasion of rock by flowing water, blowing wind and moving ice.

· What is CBR? The California bearing ratio (CBR) is defined as the ratio of test load to the standard load, expressed as percentage for given penetration of the plunger.                                 CBR = (test load/standard load) 100 Rough value of CBR = q/10 (Where q = bearing capacity of soil.)

·   What is undisturbed and disturbed sample of soil? 1.    Undisturbed sample:- The soil sample, in which natural structure and properties remains preserved is called undisturbed sample of soil. These are taken in soil surveying and boring operation. 2.    Disturbed sample:- The disturbed sample, in which the natural structure of soil gets partly modified and destroyed are termed as disturbed sample of soil. Such sample may be collected by auger boring.

·   What is sieve analysis? The sieve analysis mainly adopted for sand and gravel. It consist of sieving on oven dried soil, which pulverized by wooden mallet through a set of different IS sieve specialized for the purpose in I.S. 460 .

·   What is the role of water in compaction? Moisture content plays very important role in densification of soil. When the moisture content is low, the material is stiff and difficult to compress and the dry soil density is low , when the moisture content is increased, soil particles are lubricated and the soil becomes soft, plastic and easier to compaction. Thus, the dry soil density increased and reaches a maximum.

·   What is passive earth pressure? This is maximum pressure because the earth pressure does not increase beyond the passive state with further movement of the earth retaining structure.

·   What is active earth pressure? The pressure, which the soil develops in response to the movement of the earth retaining structure away from it, is called active earth pressure. This is the minimum pressure, because earth pressure does not decrease beyond the active state with further movement of the earth retaining structure.