Rankine's and coulomb earth pressure theory can not be used for the computation of the lateral earth pressure on sheetings, as those theories are applicable to rigid retaining walls rotating about the base. The sheeting and bracing system is somewhat flexible and rotation takes place at the top of the wall. Sheeting are placed against the walls of the excavation when these are shallow. The upper strut is placed when the excavation is shallow and the lateral yield of the soil has occurred. As the excavation proceeds downwards, the lower part of the face is free yield inward before the next strut is placed. The inward yield of the soil increases with an increase in the depth of excavation. Thus the sheeting tilts about its top.The method of earth pressure of calculation has been developed by Terzaghi based on the observations of actual loads in struts in full scale excavations in sand in BERLIN and in soft clay in CHICAGO. Pressure distributions against the sheeting have been approximated on the assumptions that each strut support the sheeting area. The effect of various factors is not fully understood. However, the results of the field studies can be used as a basis for developing earth pressure diagram required for the design of the bracing system. The pressure diagram recommended for design represent an envelope which encompass the actual pressure distribution diagram obtained from the field tests.These design pressure diagram are also known as apparent pressure diagram.

Fig. shows the apparent pressure diagram suggested by the Peck (1969) . Fig. Gives the pressure diagram for braced cut in dry or moist sand. The pressure diagram is uniform with a pressure ( ) equal to 1.6( /H) or (0.65. .H. ).

Where is Rankine's earth pressure coefficient, given by .

And = Total normal active pressure on a wall of height H determined by coulomb theory .

The resultant active earth pressure diagram is 28% greater than the coulomb active pressure for dense sand & 44% greater than for loose sand. Since, the sheeting can not resist, in general, the vertical shear forces, the friction and adhesion on them are assumed to be Zero.

Fig shows the pressure diagram for the clay.