Diaphragm walls

An apparatus comprising:

• at least one of guide tube for casting into a concrete panel of the diaphragm wall along a height of a face of the concrete panel, the guideway tube comprising:
• an elongate guideway track having an elongate internal volume for receiving a guide to travel therealong, the guideway track comprising at least one elongate side wall and an elongate slot along the at least one elongate side wall, the elongate slot having a first width;
• and a removable elongate closure panel comprising:
• a rear panel portion configured to close the elongate slot in the at least one elongate side wall and, along with the at least one elongate side wall, configured to form a ring-shaped side wall of continuous periphery enclosing the elongate internal volume;
• and a front panel portion of a second width greater than the first width, whereby the removable elongate closure panel can be pushed out from the elongate slot when a guide travels along the elongate internal volume;
• at least one water-stop locator element;
• and
• a continuous elongate water-stop for positioning near or adjacent the elongate slot along a height of the guideway track,
• wherein the guideway track comprises two elongate wings each extending externally from the at least one side wall adjacent elongate slot to form an extended elongate slot, and
• wherein the at least one water-stop locator element comprises at least one carriage member configured to engage one or more of the wing members to locate the water-stop near or adjacent the elongate slot, or the extended elongate slot, along a height of the guideway track.

A method of constructing a diaphragm wall comprising:

• a) providing at least one of guide tube for casting into a concrete panel of the diaphragm wall along a height of a face of the concrete panel, the guideway tube comprising:
• an elongate guideway track having an elongate internal volume for receiving a guide to travel therealong, the guideway track comprising at least one elongate side wall and an elongate slot along the at least one elongate side wall, the elongate slot having a first width;
• and a removable elongate closure panel comprising:
• a rear panel portion configured to close the elongate slot in the at least one elongate side wall and, along with the at least one elongate side wall, configured to form a ring-shaped side wall of continuous periphery enclosing the elongate internal volume;
• and a front panel portion of a second width greater than the first width, whereby the removable elongate closure panel can be pushed out from the elongate slot when a guide travels along the elongate internal volume;
• b) casting the guideway tube into a first concrete panel along a height of an end face of the panel;
• c) separating the closure panel from the guideway track, and breaking any frangible connections between these, where provided, so as to open one or more slots exposing an internal volume of the guideway track;
• and
• d) pouring a second concrete panel, so that concrete enters the internal volume of guideway track.