Precast Concrete Tunnel Lining Bolt and Shear Pockets Hydraulic Review

Abstract

With the increasing necessity and demand for trenchless construction in urban environments, the use of precast concrete tunnel lining (PCTL) for tunnel boring excavations in select ground conditions has grown due to its ease of installation and increased quality control. For wastewater applications where the PCTL is designed to function as the host pipe, the typical assumed condition for optimal hydraulic performance is to fill all bolt and shear pockets. However, this activity can result in considerable schedule and cost impacts and requires the need to quantify the benefits. A literature review was completed to substantiate roughness coefficients applicable to PCTL acting as a primary liner, and a comparison of common hydraulic equations was performed to provide a sensitivity analysis.

This paper quantifies the benefit of filling versus not filling bolt and shear pockets on the hydraulic performance of the tunnel to determine whether this activity is warranted.