Precast Concrete Segmental Liners for Large Diameter Road Tunnels: Laboratory Testing
-
2023-12-11
-
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Right Statement:
-
Geographical Coverage:
-
Edition:Final Report
-
Corporate Publisher:
-
Abstract:An experimental program was undertaken to examine thrust jack load, joint rotation stiffness and chloride ingress under pressure in large diameter steel fiber reinforced concrete (SFRC) and hybrid SFRC + steel rebar reinforced liner segments. Thrust jack load testing on 450 mm thick segments showed that (a) radial bursting stress governs SFRC segment failure; (b) maximum radial bursting stress occurs at a distance of 0.4-0.5 times the segment thickness from the thrust jack load pad while maximum transverse bursting stress occurs at a distance of one-half the segment width from the thrust jack load pad; and (c) the perimeter rebar improves radial bursting stress capacity and shifts the governing condition to transverse bursting stress and mid-width of the segment. A comparison shows that the use of residual tensile strength in ACI 544.7R-16 simplified equations leads to considerable underestimation of ultimate radial-based thrust jack pad load capacity. Radial joint rotation testing on the 450 mm thick segments showed linear positive moment – rotation response (constant rotation stiffness) and nonlinear negative moment – rotation response (decreasing stiffness with increasing rotation). The commonly used Janssen model was found to underestimate joint rotation stiffness for most ranges of rotation and axial (hoop) forces. Janssen’s model was also found to underestimate the observed large rotation moments by a factor of approximately two at all axial force levels. Pressurized salt ponding durability testing on SFRC specimens showed that higher hydraulic pressures induced higher chloride concentrations within uncracked SFRC specimens. The chloride ion diffusion coefficient under 500 kPa pressure was 8-10 times greater than that at atmospheric pressure. Cracks on the order of 0.1 mm thickness exhibited chloride concentrations at potentially harmful levels, 70 mm deep in SFRC specimens after 60 days of exposure. A design scheme for field monitoring of full ring behavior is provided and detailed in the report.
-
Format:
-
Funding:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type: