8.6 Tolerances regarding plan position and verticality
8.6.1 The plan position and the verticality of the sheet piles after installation should be in accordance with the recommended values given in table 2. This table gives values for normal cases.
|Type of wall||Situation during execution||Plan position of pile top
|verticality2) measured over the top 1 m
|Sheet pile4)||on land
|Primary element of combined wall||depending on soil conditions and on length, shape, size and number of secondary elements, these values should be established in each case in order to ensure that declutching is not likely to occur|
1) Perpendicular to the wall
2) Where the design requires piles to be driven at an inclination, the tolerances specified in the table are with respect to that direction
3) May amount to 2 % in difficult soils, provided that no strict criteria regarding for example Watertightness are specified and de-clutching is not considered to become a problem after excavation.
4) Excluding straight web piles
NOTE The tolerances regarding the position and the verticality may be additive.
8.6.2 For combined walls the requirements with respect to the plan position and verticality of the primary elements are generally very strict and consequently, special measures such as rigid and stable guide frames should be applied.
8.6.3 If the toe levels of the sheet piles and of the primary and secondary elements of a combined wall after driving differ more than 250 mm from the levels specified in the design, it shall be demonstrated that the performance requirements of the design are still satisfied.
8.6.4 If the head levels of sheet piles and of primary and secondary elements after driving differ more than 50 mm from the level which is specified in the design, it should be demonstrated that the performance requirements (e.g. connections with other elements), are still satisfied. If this is not the case, the sheet piles should be made good in accordance with the execution demands.
8.7 Corrections of sheet pile position during driving
8.7.1 When driving in very hard soil layers, the stiffness and stability of the guide frame should receive special attention in order to keep transverse and longitudinal leaning and horizontal displacements of the driven sheet piles within the tolerances given in 8.6.1.
8.7.2 Chamfering or partial cutting the toe of a steel sheet pile to prevent longitudinal leaning should not be carried out, because of the risk of declutching.
8.7.3 If transverse leaning and rotation of a sheet pile occurs during driving, it should be extracted and re-driven unless other measures are sufficient.
8.7.4 If longitudinal leaning of the sheet piles occurs during driving, immediate action to counteract this should be taken, for example by pushing or pulling.
8.8 Installation of anchorages
8.8.1 The position, direction and execution of the anchorages including the connection to the walings shall correspond with the specifications in the design.
8.8.3 Ground anchorages shall be installed in accordance with the specification given in prEN 1537.
8.8.5 Consideration shall be given to sealing the anchorage holes in the sheet piles to prevent loss of soil and seepage of water.