We will discussed main points about the pre constructions planning and programming of earthworks in hilly areas in here. There is an additional steps to carry out in special area such as hill country or hilly areas, steep slopes areas. In steep country an inspection should be made for unstable areas likely to slip. These may be indicated by :-
• seepage and springs;
• lush growth of vegetation in local areas (indicating ground water);
• trees and bushes leaning downhill (indicating slippage of the surface material);
• bent trees or lack of vegetation in an otherwise timbered area (indicating large slides).
(i) Cuttings Drainage works. Culverts and other drainage works must be planned in conjunction with the earthworks construction. There must be sufficient lead time (float) provided in the program between these two operations on any section of the works to allow for possible delay in supply of pipes, delay due to wet conditions, and the time required to cure cast-in- place culverts etc. The timely construction of drains diversion banks, culvert inlets and
outlets etc., must be taken into account in this planning of earthworks construction.
(j) Assessment of Likely Material. An assessment must be made of the material likely to be found in the cuttings and of foundations for embankments so that the correct plant and methods of working can be selected for earthworks construction.
It is a sound precautionary measure that all large cuttings should be test drilled prior to excavation. The cost of drilling is small compared with the cost of wrong decisions as a result of lack of information. Test drilling should be done prior to designing of the earthwork construction job.
Before commencing earthworks construction the report on the material, the drill logs and any cores recovered should be carefully examined. The cores are retained by laboratories and the engineer should make arrangements to inspect them at the laboratory or have them transferred to the site office. The geologist and engineer who prepared the report will normally be available for discussions.
The test drilling mat be supplemented by a seismic survey. In such a survey, an idea of the hardness of rock strata is obtained from the velocity with which a shock wave is transmitted through the rock. The steel plate with a hammer. The velocity is determined by the time the shock wave takes to travel from the source to a series of recording stations laid out in a straight line.
Various tables are available for interpreting the hardness of rock from seismic velocities. Caution is required in accepting such interpretations as the degree and orientation of the jointing of the rock and size and type of machines to be used for ripping and hauling are significant factors in determining whether a particular interpretation can be economically applied.
Any existing cutting should be inspected. Where possible, trial excavation and ripping of accessible material should be carried out.
There is some points to discuss further regarding the subject of earthworks construction and how to start constructions and estimate time, machinery and manpower requirement etc.. and hope to discuss in next post.