General information

As with any building project, the construction of the slit wall must be preceded by careful exploration of the site. A slit wall is formed in individual sections (Fig. 1.3). Each section is lifted, reinforced and then concreted to the final depth. The length of the section depends on the ground and ground water ratios and the earth conditions. If there are, for example, adjacent to the slit building to be excavated, smaller sections which are larger in open terrain are to be selected. In general, this length is between about 2.5 m to 3.4 m (corresponding approximately to the width of the open slot wall gripper) and – for manufacturing reasons – about 7 to 10 m. In the production of a sealing wall, so-called endless lamellae are also possible under special conditions.

Fig. 1.3 Slotted wall elements and guide walls (source)

1 Slotted wall element

dn  Nominal thickness (width of the excavation tool)

da  Outburst thickness

lE  Length (center distance of the stop constructions)

t   Depth

h   Wall height

During concreting, a slit wall element is delimited by cut-off pipes or flat joints (“stop construction”) or by an adjacent, already concreted, slit wall element. According to the number of shut-off pipes, a distinction is made between:

– Beginner elements (“beginner”) with a shut-off pipe (a total of two) to the end of the element.Rotor element (“rotor”) with a shut-off pipe. The rotor element adjoins an already concreted slot wall element.

– Clamping elements (“NO”) without a shut-off pipe. The closure element closes the gap between two already concreted elements.

Depending on the local boundary conditions and constructional aspects, the slot wall elements can be arranged in chronological order:

(1, 3, 2, 5, 4, 7, 6, 9, 8, …) is the most important thing to do,

or

– Beginners, runners, runners, runners … Normally open (1, 2, 3, 4, …)

getting produced. Intermediate forms are also possible. For continuous utilization of the machines, a slit wall, e.g. For a larger excavation well also from several starting points.

Fig.1.4 Phases of diaphragm wall production (source [2])

In the case of the rotor and closure elements, the slot wall gripper finds a good guide through the semicircular joint produced by the shut-off pipe (see d) at the end of the previously concreted slotted wall element so that the risk of the louvers flapping out becomes smaller.