EXAMPLE 3.5.1. ESTIMATING A GROUTED RIP-RAP

A 50m long rip-rap wall is to be estimated using Class B stone with Class C grout. List down the materials required including the weep hole drain pipe and the gravel backfill as granular soil filter.

                

Using Class B grout:

STONE CLASS	A	B	C	SAND
	40kg	40kg	40kg
Class A	2.574	1.716	1.287	0.143
Class B	2.448	1.620	1.214	0.135
Class C	2.232	1.488	1.116	0.124
Class D	1.944	1.296	0.972	0.108

Lateral distance for weep holes is standardized at 2m. At the height of 4m wall, 2 layers for weep holes are to be installed. The tapering width of the wall will require two different lengths of the drain pipes.

         

 So:
          25 pcs - 3" diameter at 1.50m long
          25 pcs - 3" diameter at 1.00m long


The granular soil filter (gravel) is computed with the length of the wall multiplied by the standard cross-section:








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