COMPARISON OF CHINESE BASIC QUALITY SYSTEM WITH Q AND RMR SYSTEM FOR THE DESIGN OF TUNNEL SUPPORT SYSTEMS

Abstract

Due to the parasitic growth in the world’s population the space left for future construction is squeezing day by day. A lot of new techniques are being used these days to consume the underground space to provide working area that can be used to build roads, shopping malls, hospitals, nuclear power plants, storage houses and sports stadiums etc. In the present time, the use of tunnels is at all-time high. The preponderance of the underground excavations puts a huge demand on civil and min-ing engineers to design an effective, durable and long lasting support systems for such excavations. A problematic design of the support systems that do not conform to the requirements presented by the overlying material has led to many fatal inci-dents. The causes of the failure of the tunnel structures is usually attributed to the unfavourable ground conditions, poor design of support systems, contractors inex-perience, inadequate and inappropriate construction method. About one third of the total tunnel failure had resulted as a resulted due to the ground conditions. (Lance et al, 2007). If the information regarding the site conditions, geotechnical conditions, and the geology of the project area is not collected properly then it might lead to under design which involves costly repair work or over design of the support systems Sometimes support systems may fulfil the present demands but the prevailing geol-ogy and geotechnical conditions might change with time. In such cases the support systems might not be able to carry out imposed load over the life of the underground excavations. It is possible that what was considered safe during the construction phase of the excavation might not meet the current safety requirements later. (Szwedzicki, 2005) xvii It is the need of the time, to put some good effort in the research of support systems that can culminate in bring new techniques and methods which would enable us to design them economically, safely and with confidence. In this research, first of all the rock type and quality using different rock clas-sifications systems like Rock quality designation (RQD), Q system, Rock Mass rat-ing (RMR) and Rock structure rating (RSR) are determined. Details about weather-ing, presence of any structural feature, water inflow inside the tunnel and uniaxial compressive strength of the rock is gathered from the tunnel site. After classifying the rock and defining its quality and RQD value the next step was to determine the rock load. Once the load has been calculated, the support systems are designed which included the thickness of shotcrete lining, length of rock bolts and spacing of rock bolts. These support systems are designed using various empirical methods, using ground reaction curve and using ROCSCIENCE software. After designing the support systems, a comparison of the support systems using different technique is made and the results of this comparison are compared with the design being implemented at the Shimla tunnel