Quality Supervision for Foundation Works

1. Quality supervision of foundation works should be provided by the RSE and his TCP T5 and T3, as well as by the AS of the RSC and his TCP T4 and T2. Depending on the nature of the various stages of foundation works, TCPs should either be full-time on site or inspect certain percentage of the works as specified in this Code.

1. The stages of the various types of foundation works are shown in Table 6.3. Actual supervision requirements will be imposed by the BA at plan approval and consent stage on a case-by-case basis depending on the scale and extent of the foundation works.

Table 6.3 Stages of Various Types of Foundation Works
Item No.	Stage	Description
F1	Driven Piles   Setting out of piles	Check that the locations of piles agree with approved plans.
F2	(ii)     Driving test	Check that design assumptions agree with actual site conditions during driving tests.
F3	(iii) Driving of piles	Check that the accepted working procedures of pile driving are followed and anomalies  rectified during pile driving.
F4	(iv)    Splicing of piles	Check the accuracy of design details during pile splicing.
F5	(v)     Final sets	Check that the required final set has been achieved and the capacity of each pile complied with approved plans.
F6	(vi) Proof test (Verification on the performance of the as-constructed piles by the imposition of test load)	Check that the testing procedures and acceptance criteria of proof tests are in accordance with PNAP APP-18 (previously PNAP 66) and measurements are properly recorded during the test.

Table 6.3 Cont’d

F7	Large Diameter Bored Piles, Barrette Piles and the like   Setting out of piles	Check that the locations of piles agree with approved plan.
F8	(ii)     Pre-drilling (To determine the proposed founding levels of piles)	Supervise the pre-drilling operation; the logging of soil/rock samples, and to measure the depth of drillholes. Ensure that the retrieved samples are not tampered.
F9	(iii) Verification of founding stratum	Measure the depth of excavation and check the quality of retrieved materials at the founding stratum.
F10	(iv) Installation of piles (Grouting operation when required)	Check that proper working procedures of pile installation are followed and anomalies rectified. Check the correct grout mix, grout pressure and grout volume are being used and the adjacent building structures are not adversely affected.
F11	(v)     Preparation of pile base	Ensure that pile base is clean.
F12	(vi) Fabrication and installation of rebar cage and placing of concrete	Check that sufficient and correct amount of rebars are provided and proper concreting method is used.
F13	(vii) Interface core-drilling	Check that the quality of concrete and foundation rock conforms with that specified in the approved plan and that concrete and rock are in good contact at the interface.
F14	(viii) Proof test (Verification on the performance of the as-constructed piles)	Supervise the core drilling operation of the proof test and the logging of concrete/rock samples and measure the depth of drillhole. Ensure that retrieved samples are securely stored and delivered to laboratory for testing.
F15	Mini-piles, Socketted H-piles and the like   Setting out of piles	Check that the locations of piles agree with approved plan.

Table 6.3 Cont’d

F16	(ii)     Pre-drilling (To determine the proposed founding levels of piles)	Supervise the pre-drilling operation; the logging of soil/rock samples, and to measure the depth of drillholes. Ensure that the retrieved samples are not tampered.
F17	(iii) Verification of founding stratum	Measure the depth of excavation and check the quality of retrieved materials at the founding stratum.
F18	(iv)         Installation of piles (Grouting operation when required)	Check that proper working procedures of pile installation are followed and anomalies rectified. Check the correct grout mix, grout pressure and grout volume are being used and the adjacent building structures are not adversely affected.
F19	(v)     Installation of rebar and grouting	Check that sufficient and correct amount of rebars are provided and proper grouting method is used.
F20	(vi) Proof test (Verification on the performance of the as-constructed piles by the imposition of test load)	Check that the testing procedure and acceptance criteria of the proof tests are in accordance with PNAP APP-18 (previously PNAP 66) and measurements are properly recorded during the test.
F21	(vii) Post-installation borehole drilling	Verify the rockhead profile and socket length of piles during post-installation borehole drilling.
F22	Rafts and Spread Footings   Setting out of rafts and spread footings	Check that the locations and sizes of rafts and spread footings agree with approved plan (or the submitted plans for minor works).
F23	(ii)     Inspection of bearing stratum	Check the compliance of ground bearing stratum with approved plans (or the submitted plans for minor works), site investigation reports and design assumptions.
F24	(iii) Fixing of rebars and checking of concrete covers	Check that sufficient amount of rebars and good workmanship are provided.
F25	(iv)    Placing, compaction and curing of concrete	Ensure the quality and workmanship of concrete works.
F26	(v)     Plate loading test (where required) (To verify the adequacy of ground bearing stratum)	Check that the accepted testing procedures of plate loading test are followed and measurements are correctly recorded.

Note : Foundation unit inspected should be shown in the checklist by each member of the supervision team.

1. The AP, RSE and RSC should jointly submit a supervision plan, specifying the name of the TCPs appointed and frequency of inspection and/or extent of supervision, and carry out inspections and supervisions in accordance with the plan. The plan should be submitted prior to or at the same time as consent application for the foundation works. However, no prior approval of the TCPs is required before commencement of the foundation works. The AP/RSE/RSC are responsible to ensure that their TCPs satisfy the qualification and experience requirements specified and should notify the BA of any subsequent changes of TCPs. The plan should be kept on site for the inspection of the BA when required.

1. The RSE should provide supervision as necessary during all stages in Table 6.3.

1. The AS of the RSC should provide supervision as necessary during all stages in Table 6.3.

1. Pre-drilling, interface core-drilling, post-installation drilling and proof test core-drilling for foundation works must be carried out by a Registered Specialist Contractor in the Ground Investigation Field Works category and be supervised by the site supervisors responsible for the quality supervision of foundation works. There is no need to submit a separate supervision plan for the pre-drilling and post-installation drilling works.