Desain Tumpukan Gelugu (Kelapa Gelondongan) sebagai Penyangga Terowongan Pertambangan dalam Format ASD dan LRFD.

Abstract

Coconut-logs will be used as coco-logs-crib material for supporting mine tunnel. Density and mechanical properties of coconut-logs must be well identified before designing coco-logs-crib. This research estimates the density and mechanical properties of coconut-logs by reconstruction methods. Coconut-logs are reconstructed by replacing each small clear speciment on its natural place, then the properties are estimated by mechanics, statistics, calculus and geometric analytic equation. This method is successful estimating density, modulus of elasticity, shear modulus, and modulus of rupture, but fail estimating Poisson’s ratio. This research is conducted to design three coco-log-cribs, namely: single crib, interspace crib, and double interspace crib. Each coco-log on on the top of singgle crib, interspace crib, and double interspace crib are capable to handle 99 N/mm, 98 N/mm, and 185 N/mm load combination based on ASD respectively, so the capacity of each structure are 396 kN, 588 kN, and 1110 kN. Based on LRFD, the load combination looks like 1,296 times greater than ASD. The difference appears because of the different load combination format, so it doesn’t mean that LRFD will save material than ASD. The material size justified by LRFD or ASD will be similar. Material efficiency of double interspace crib is the best than two others. The material efficiency of single crib, interspace crib, and double interspace crib are 5,08 kN/m (71 kN/tree); 5,76 kN/m (81 kN/tree); and 8,81 kN/m respectively. The best structure should have capacity near enough with actual demand, so it could be justified after evaluating the actual load combination