Bosworth Plastics Limited
The Dowelock System
The Bosworth Plastics range of Locking Dowels is specifically designed to meet the performance demanded from the tunneling industry and to meet the requirements laid down in the British Tunneling Society's Specification for Tunneling.
DOWELOCK consists of connecting dowel molded from a high-strength, high durability plastic, together with two locking assemblies; one cast into each of the adjacent tunnel lining segments. These locking assemblies incorporate patented locking collets that allow the dowel to enter with a minimum compression force and then lock, thus preventing the dowel from withdrawing.
DOWELOCK can be used with all types of lining including Trapezoidal Rings as the collets are retained in such a way as to allow the dowel to be entered off line. The tapered dowel acts finally in the alignment of the segments before locking and providing resistance to both tensile and shear forces. The full locking capacity of the DOWELOCK is maintained with up to a 15mm gap between adjacent units.
DOWELOCK is designed to operate with both hydrophilic and compression gaskets. The dowel has the performance to restrain forces generated by both types of gaskets minimizing joint gaps and offsets.
DOWELOCK (Steel Core): Where greater shear and tensile loads are required Bosworth Plastics offer a steel zinc coated plastic sleeved dowel giving tensile loads in excess of 90 Kn along with shear value in excess of 280 Kn.
Dowelock / Gasket interaction
DOWELOCK has minimal extension under load ensuring efficient sealing with EPDM compression gaskets. Tests have shown that extension equilibrium is achieved at approximately 2.0 mm for typical compression gaskets with closure forces of 25 to 30 kN/m run.
Dowelock Performance
Tested average UTS = 57 Kn
The Locking efficiency of the system is 98%
Plastic Dowel Shear strength > 120 Kn
Steel Dowel Shear strength > 280 Kn
