2. During an excavation for a tunnel, 250 m below ground level, a highly fractured siltstone rock mass with two major joint sets and many random fractures is encountered. The RQD from the rock cores is 55% and the average UCS is 92 MPa. The joints with average spacing of 75 mm are rather continuous with high persistence with apertures of 3-5 mm, and they are filled with silty clay. The joint surface walls are highly weathered, undulating, and slickensided. There is some water inflow into the tunnel estimated as 15 L/min per 10 m of tunnel length, with some outwash of joint fillings. Estimate RMR, Q and GSI. Assume a unit weight of 28 kN/m³ for the rock mass.

2. During an excavation for a tunnel, 250 m below ground level, a highly fractured siltstone rock mass with two major joint sets and many random fractures is encountered. The RQD from the rock cores is 55% and the average UCS is 92 MPa. The joints with average spacing of 75 mm are rather continuous with high persistence with apertures of 3-5 mm, and they are filled with silty clay. The joint surface walls are highly weathered, undulating, and slickensided. There is some water inflow into the tunnel estimated as 15 L/min per 10 m of tunnel length, with some outwash of joint fillings. Estimate RMR, Q and GSI. Assume a unit weight of 28 kN/m³ for the rock mass.

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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