Application of RMR, Q, and Japanese Rock Mass Classification Systems for Design of Support Systems of the Narogong Weir Diversion Tunnel, West Java, Indonesia

Abstract

This study aimed to propose alternative support systems for a diversion tunnel at the Narogong Weir, West Java, based on the Rock Mass Rating (RMR), Tunnelling Quality Index (Q), and Japanese Rock Mass Classification systems. Surface geological mapping, drill core evaluation, and laboratory testing were conducted to characterize the engineering geological conditions of the tunnel construction site. The results showed that the study area consisted of alternating layers of siltstone and marlstone of the Jatiluhur Formation. Joints and an anticline are the main geological structures observed in the study area. The uniaxial compressive strength (UCS) values of the intact rocks ranged from 4 to 25 MPa. The rock masses were classified into poor to fair classes. The diversion tunnel was divided into two segments of tunnel support systems. Although the support system characteristics are slightly varied, in general, the rock mass classifications recommended rock bolts and shotcrete as the primary tunnel support systems.

Multi-Rock Mass Classification Systems for the Assessment of Excavation Method and Support Design of Spillway Tunnel, Sidan Dam, Bali, Indonesia

“…On the other hand, one or more rock mass categorization methods may be used to develop an understanding of the composition and features of a rock mass to offer early estimates of support needs and estimations of the rock mass's strength and deformation properties [4]. Several tunnel constructions, including roads [5], railways [6], and dam tunnels [7], have already benefited from the application of multiple evaluation systems. Furthermore, this research could suggest the required type and the quantity of tunnel support.…”

Rock mass classification in highway tunnel engineering during exploration phase and case study

“…Furthermore, groundwater, squeezing and swelling or stability conditions of rock mass, and filling materials in joints will scale their effects. Dozens of approaches, qualitatively or quantitatively, were developed to evaluate rock mass quality of underground or slope engineering or worldwide in recent decades [3,4]. Surrounding rock classification is carried out by means of field or laboratory tests during the investigation phase of a tunnel, and provides the essential foundation for subsequent tunnel design and construction.…”