4.2.7.

(1) A deep foundation unit shall provide support for a building by transferring loads by end-bearing to a competent stratum at considerable depth below the structure, or by mobilizing resistance by adhesion or friction, or both, in the soil or rock in which it is placed.

(1) Deep foundation units shall be designed in conformance with Subsection 4.2.4. and this Subsection.

(2) Where deep foundation units are load tested, as required in Clause 4.2.4.1.(1)(c), the determination of the number and type of load test and the interpretation of the results shall be carried out by a person especially qualified in this field of work.

(3) The design of deep foundations shall be determined on the basis of geotechnical considerations taking into account,

(a) the method of installation,

(b) the degree of inspection,

(c) the spacing of foundation units and group effects,

(d) other requirements of this Subsection, and

(e) the appropriate structural requirements of Section 4.1. and Subsections 4.3.1., 4.3.3. and 4.3.4.

(4) The portion of a deep foundation unit permanently in contact with soil or rock shall be structurally designed as a laterally supported compression member.

(5) The portion of a deep foundation unit that is not permanently in contact with soil or rock shall be structurally designed as a laterally unsupported compression member.

(6) The structural design of prefabricated deep foundation units shall allow for all stresses resulting from driving, handling and testing.

(1) Permissible deviations from the design alignment and the location of the top of deep foundation units shall be determined by design analysis and shall be indicated on the drawings.

(1) Where a deep foundation unit has not been placed within the permissible deviations referred to in Article 4.2.7.3., the condition of the foundation shall be assessed by the designer.

(1) Deep foundation units shall be installed in such a manner as not to impair,

(a) the strength of the deep foundation units and the properties of the soil or rock on or in which they are placed beyond the calculated or anticipated limits,

(b) the integrity of previously installed deep foundation units, or

(c) the integrity of neighbouring buildings.

(1) Where inspection shows that a deep foundation unit is damaged or not consistent with design or good engineering practice,

(a) such a unit shall be reassessed by the designer, and

(b) any necessary changes shall be made and action taken as required.