The TTMJ system is the new diaphragm wall joint system ensuring full width concrete to concrete contact to any depth with the facility to provide an effective water stop, a shear key and a tension connection across the joints, none of which is possible with an hydromill.
The TTMJ system offers the possibility to construct “perfect” joints to greater depth, following the profile of the primary panel with a mill (the joint trimmer) that is guided by tracks previously cast into the primary panel (after the secondary panel has been excavated and before it is concreted) ensuring the quality of the joints in the completed DW. The basic work stream is summarized in the following render video.
The key to any successful innovation is to combine a straightforward system - the guide tracks - with a standard piece of equipment - the trimmer - to deliver a significant step forward - the TTMJ System.
Guide tracks are cast in to the primary panel concrete to the required depth. When the primary panel concrete has attained sufficient strength (~20MPa), the secondary panel can be excavated to full depth. The TTMJ trimmer can then be run down the joint, removing the sacrificial section of guide track, and cutting a profile which can include a shear key.
The guide tracks are designed and tested to avoid distortion and withstand the forces trying to pull the trimmer guides away from the centre line of the joint.
With the joint profiled to required depth, concrete cuttings are removed from the trench and the secondary panel can be concreted.