The external tube design concerning wave loads and currents has been discussed in great detail for coastal protection tubes during the last years. A lot of research dealing with this topic has been carried out. The additional external design aspect, the geotechnical stability of the tube installation area, can be managed by conventional geotechnical analysis. Also the performance of dewatering tubes has been analyzed extensively. Yet, not covered in detail has been the internal tube design concerning two dominating aspects: The filling degree with a proper definition and the seam orientation. Especially the seam orientation and as a consequence the acting loads on the seams substantially influence the integral tube stability. In addition the type of seam being used affects the tube integrity. Based on seam type and the current tube fabrication methods a general design guidance for the tube seaming pattern has been derived. In combination with the filling degree a tube design factor called the Tube Performance Factor (TPF) has been developed in accordance with the “overall” strength-reduction material factor of the CUR guideline “Geosystems. Design Rules and Applications”.
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