【法规名称】
【法规编号】 79807 什么是编号？
【正 文】
第7页 CAP 123B BUILDING (CONSTRUCTION) REGULATIONS
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[接上页] (a) acceptable foundation engineering principles; or (b) tests on the foundations on site,with an adequate factor of safety appropriate to the type of pile, taking into account ground conditions, the method of installation and group effects. (3) Where pile foundations are installed through a stratum which is likely to undergo consolidation after the foundations are in place- (a) the frictional resistance of the consolidating stratum and the overlying soil shall not be taken into account in the determination of the load carrying capacity; and (b) the downward frictional force exerted from the consolidating strata and the overlying soil shall be considered as imposed load.(4) Subject to the provisions of subregulation (5), the spacing of piles shall be determined with due regard to the nature of the ground, the method of construction and the group effects and shall be sufficient to prevent damage to the piles or any adjacent construction. (5) The centres of all piles deriving their resistance mainly from friction and of all driven piles shall be placed- (a) not less than the length of the perimeter of the pile or 1 m, whichever is the greater, from the centres of adjacent piles; and (b) not less than half the length of the perimeter of the pile or 500 mm, whichever is the greater, from the site boundary.(6) Where piles are placed in such proximity that the load carrying capacity of the piles may be affected by other piles a pile group shall be deemed to exist and the allowable load on any group of piles shall not exceed the sum of the load carrying capacities of the piles in the group multiplied by a group reduction factor determined in accordance with subregulation (7). (7) The group reduction factor shall be determined by recognized foundation engineering principles with respect to the bearing capacity and settlement of the pile group taking into account all the circumstances including the nature of the ground, the length and spacings of the piles, the size of the group and the method of construction. (8) The driving of piles shall take into account the properties and deformation characteristics of the pile, hammer and cap-block in order that the driving energy will be applied in such a manner so as not to damage the material of the pile. (9) Subject to the provisions of subregulation (8), all driven steel and precast reinforced concrete piles shall be designed with an average compressive stress on the nominal cross sectional area at working load not exceeding- (a) 0.4 uw/F, in the case of precast reinforced concrete piles; and (b) 0.6 fy/F, in the case of steel piles,where fy is the yield stress of the steel, uw is the specified grade strength of the concrete, and F is the design safety factor on driving, with a minimum value of 2 for dead and imposed loads and 1.6 for combined dead, imposed and wind loads. (Enacted 1990) Cap 123B reg 27 Cast-in-place concrete foundations (1) The concrete stresses in cast-in-place concrete foundations at working load shall not exceed- (a) the appropriate limitations of design stresses of the concrete, in the case of concreting in dry conditions; (b) 80% of the appropriate limitations of design stresses of the concrete, in the case where groundwater is likely to be encountered during concreting.(2) Subject to the provisions of subregulation (1) the average compressive stress on the nominal cross sectional area of cast-in-place concrete piles of least lateral dimension not exceeding 750 mm shall not exceed 5 MPa under working load due to dead and imposed loads and shall not exceed 6.25 MPa under working load due to combined dead, imposed and wind loads. (3) In-situ concrete linings in all cast-in-place concrete piles shall not be considered as contributing to the structural strength of the foundation. (Enacted 1990) Cap 123B reg 28 Horizontal restraints to piles and pile caps Adequate horizontal restraints in at least 2 directions shall be provided to individual piles or pile caps. (Enacted 1990) Cap 123B reg 29 On site tests to be made where doubt exists Where the Building Authority has any doubt as to the design assumption or load carrying capacity of any foundation, he may require tests to be made on site on the foundation or on the ground in which the foundation is placed by the imposition of a test load or any other suitable method. (Enacted 1990) Cap 123B reg 30 Proof tests on foundation units A sufficient number of proof tests are to be carried out on representative foundation units to ascertain the performance of the foundation under load by means of- (a) the imposition of test loads; or (b) core drilling of the completed cast-in-place concrete foundation; or (c) any other suitable method,as appropriate to the type of foundation. (Enacted 1990) Cap 123B reg 31 Ground treatment (1) Where improvement of the load carrying capacity of the ground is to be achieved by ground treatment, adequate proof of the suitability of the method and materials to be used shall be given. |
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