ADDITIONAL CONDITIONS OF CONTRACT
FOR SOIL INVESTIGATIONS AT NATIONAL PHYSICAL LABORATORY
NEW DELHI
1.0 The following Additional Conditions of Contract shall be read in conjunction with General Conditions of Contract. If there are any provisions in these Additional Conditions of Contract, which are at variance with the provisions of General Conditions of Contract, the provisions in these Additional Conditions of Contract shall take precedence.
2.0GENERAL INFORMATIONS
Contract Documents
The Conditions of Contract, the Bill of Quantities and the Drawings shall be read in conjunction with this Specification and matters referred to or shown or described in any of the former are not necessarily repeated in the latter.
3. 0 Scope of Contract
The work consists of borings, and drilling holes as shown in the drawing including laboratory testing. The work which will be carried out under the direction and supervision of the Engineer, are for the purpose of ascertaining the profiles and engineering properties of the soils and rock, if any, in the project areas.
4. 0 Drawings
Locations of Boreholes are shown in the enclosed drawings.
5.0Extent of the Investigation
(a) 5 nos. of boreholes are proposed to be carried out at locations marked in the drawing. The boreholes are to be sunk to a level as specified or into hard rock as specified and directed by the Engineer. These locations are likely to be changed during execution of field work.
(b) Standard penetration tests are to be conducted inside each borehole as specified.
(c) Laboratory tests on the soil, water and rock samples are to be carried out and a detailed report submitted as laid down in this specification.
6. Setting out of the Works
The Contractor shall be responsible for the setting out of the position of borehole, as per drawings/ instructions.
7. Particulars of the Site
The Site of Works is located at NPL Campus, New Delhi – 110012.
Information regarding the Site may be obtained by the Tenderer independently from the Engineer.
8. Access to the Site
Prior approval of the Employer/Engineer for working at the Site and using the access routes thereto shall be obtained by the Contractor before commencing work.
9. Contractor's Working Area
Contractor will be allotted a suitable, working area near the Site of works by the Employer. The Contractor shall make his own arrangements at his own cost for providing his Site office and other facilities.
10. Transport to the Site
The Contractor shall be responsible for the provision of all necessary transport, whether for personnel, plant, stores, equipment or samples.
11. Night Work
No night work is normally permitted unless otherwise approved by the Engineer. All necessary precautionary arrangements for working at night, if permitted, shall be made by the Contractor to the satisfaction of the Engineer.
12.Areas Available for the Works
All necessary arrangements shall be made by the Contractor with the Employer/Engineer with regard to entry and use of a suitable working area to accommodate the contractor's temporary site office, stores, etc. No labour will be allowed to stay within the Site and the Contractor will have to operate with his labour residing outside the Site, unless otherwise permitted in writing by the Engineer. The Contractor shall carry out all negotiations/ arrange all temporary wayleaves and deal with any claims for compensation which may arise out of the normal use of an access to the working areas by the Contractor. The limits of each working area and wayleave will be indicated to the Contractor by the Engineer and the Contractor shall confine Ills activities to the areas thus indicated.
The Contractor shall not use any portion of the Site for any purpose not connected with the Works unless prior written permission has been obtained from the Engineer.
The Contractor shall exercise every care in gaining access to the various working areas and in setting up and operating his plant so as to avoid damage to property.
If instructed by the Engineer, the contractor shall remove any plant, etc. or other obstruction within his control, promptly and at his own expense.
The Contractor shall keep all plant, equipment, materials and the areas of the site in reasonably good order and tidy to the satisfaction of the Engineer throughout the course of the Works. Upon completion of his operations in any working area, the Contractor shall fill in, plug and consolidate the boreholes, remove all arisings and make good any damage caused by his operations at his own expense and to the satisfaction of the Engineer.
13. Personnel and Supervision
The Contractor is to supply suitable personnel to conduct the subsoil investigation and such personnel are to be skilled in the work required by the Contract. The work is to be done under the proper supervision of supervisors fully qualified in their respective duties with regard to making borings, taking samples, identifying soils/rocks and carrying out tests on soils/rocks at site and in the laboratory.
In addition, the Contractor shall maintain at site a representative who will be in overall charge of the works and who shall be thoroughly versed in all aspects of boring and drilling, sampling and the field testing work specified herein. The contractor shall engage qualified experienced engineers/ geologists with relevant experience for this work at the site. Detailed bio-data of the personnel proposed to be deployed should be submitted with the tender.
14. Supply of Water and Electric Power
The Contractor shall make his own arrangements for the supply of water and electric power at his own cost.
A. BORING & SAMPLING
15. Boring
Boring shall be carried out in accordance with the provisions of 1S:1892-1979 with shell and auger equipment. The boreholes shallhave a minimum diameter of 150 mm and shall be suitably lined throughout. The toe of the lining shall at no time be more than 1.0m above the level to which the material has been removed from the borehole.
Before taking any undisturbed samples or making any in situ test, the lining shall be carried down to the bottom of the borehole.
Auger of proper size shall be used in soft. to firm clays and silts to avoid suction. The use of shell only be restricted to moderately stiff to hard clays and sandy strata below water table. The use of a chisel bit shall be permitted only in boulder or rock formation or through local obstructions, etc.
Uncased boreholes may be permitted only upto a depth where the sides of the hole can stand unsupported. In case side falls or squeezing is noticed, steps shall be taken immediately to stabilize the sides of the borehole by casing pipes as directed by the Engineer. Bentonite slurry may be permitted to stabilize the borehole as directed by the Engineer.
Wash boring or any similar methods of boring, employing a water jet and/or a percussion bit may be permitted by the Engineer in case boring and sufficient progress becomes impossible considering the sub-soil condition.
No water shall be added while boring through cohesive soils and cohesionless soils above the water table. While boring through cohesionless soil below water table, water level in the casing shall always be maintained at or above the water table.
The cutting brought up by the auger, shell or the cutting shoe of the split-spoon or undisturbed sampler shall be carefully examined and the soil description duly recorded after performing field identification tests.
After completion of the boring at any borehole, a borelog shall be prepared in an approved proforma or as per IS:1892-1979 and submitted to the Engineer in duplicate. After observing the position of the water table, backfilling of the borehole shall be carried out in an approved manner as directed by the Engineer.
16. Disturbed Samples
Disturbed samples shall be taken from borehole cuttings, split spoon sampler and cutting edge of undisturbed sampler for clarification tests at the site in duplicate. The samples should be taken at 1.0m interval or at every identifiable change of strata, whichever is met earlier to give a reliable record of the variations in the conditions of the scils. If sent to the laboratory for testing or handed over to the Engineer in airtight container for the purpose of record.
17. Undisturbed Samples
Undisturbed samples shall be taken from the boreholes at the following intervals or at every identifiable change of strata whichever is met earlier:
0 to 5m at 1.5m intervals
Below 5m at 3m intervals
(Distances being measured below the existing ground/bed level).
In case of sandy strata, the intervals of sampling shall be suitably increased. Sampling procedures and samplers for if-covering undisturbed samples shall normally conform to IS:2132 (latest edition) unless otherwise specified and directed by the Engineer.
In the case of cohesive deposits, undisturbed samples shall be taken by an open tube sampler or a piston sampler. The size of the sampler should be such that a sample having a minimum size of 100mm diameter and 300mm long can be recovered. The sampler shall be pushed strictly by hand or by jacking in soft to firm deposit and no hammering shall be allowed. Where this is not possible the sampler may be driven by the blows of a monkey having sufficient weight. Area ratio of all samplers shall be limited to 10% for soft to firm cohesive deposit and use of thick walled samplers may be permitted in case of deposits having very high consistency, subject to the approval of the Engineer. Recovery ratio shall be observed and reported in the borelogs, for every sample. The samples shall be sealed, packed and properly labelled and transported to the laboratory as laid down in IS:2132. The Cop and bottom of a sample must be indicated clearly on the sample tube to facilitate the laboratory testing in proper orientation as as specified by the Engineer.
18. Despatch of Samples
Samples shall be despatched to the laboratory as soon as possible after being obtained and shall not be allowed to accumulate on site. If it appears to the Engineer that there is a danger of samples deteriorating through further storage, the Contractor shall despatch such samples as soon as directed by the Engineer.
19. Standard Penetration Test
Standard Penetration Test (SPT) shall be conducted as per IS:2l31 at the following intervals or at every identifiable change of strata, whichever is met earlier.
0 to 20m at 1.5m intervals
Below 20m at 3m interval
(Distances being measured below the existing ground/bed level).
The driving of the split-spoon shall be terminated only when no. of blows is greater than 100 per 30 cms. of penetration. The test shall be conducted after driving the- casing to the bottom of the borehole and after cleaning it.
20. Field Dry Density Test
Field Day Density tests shall be carried out as per IS:2720 - Part XXVIII. These tests are to be conducted at selected locations after removing top 0.3m of soil. Approximately 10 kg of disturbed samples shall be collected from the test locations after conducting the tests. The disturbed samples shall be tested for natural moisture content and standard proctor density to determine maximum dry density and optimum moisture content. The disturbed soil samples shall also be tested for Liquid and Plastic limit and grain size analysis.
21. Daily Boring & Drilling Report
Complete record of boring and drilling shall be submitted along with drill observers remarks as per the proforma in Annexure 4 for all tile boreholes.
C.LABORATORY TESTS
22. General
Laboratory tests shall be carried out in consultation with the Engineer and as per IS:2720 (relevant parts). For this purpose a list of all undisturbed samples and core samples collected from each borehole/core drill shall be submitted to the Engineer with records of complete core-logging and in-situ tests in duplicate. One of the copies shall be returned to the Contractor indicating the tests to be conducted. The results of all tests shall be submitted in the proforma shown in the Annexures along with relevant graphs, etc.
23. Preparation of Test Specimens:
Preparation of test specimens for the various tests shall be carried out as per the procedures laid down in the various relevant IS Codes.
In case of soft to firm cohesive undisturbed soil samples, test samples for all types of shear tests shall be prepared strictly by hand trimming or soil lathe. Care shall be taken against bending of soil samples at the time of horizontal ejection of the samples from the sampling tubes. Samples shall be ejected' from the sampling tubes in the same direction of travel in which the samples entered the sampling tubes.
Similarly test specimens for consolidation tests shall also be prepared to the required size by hand trimming only and the ring of the consolidation apparatus shall be inserted by pressing gently with the hands and carefully removing the material around the ring. In no case shall the ring be forced into the soil. Great care shall be taken during the trimming of the sample from the top and the bottom of the ring. The Test specimen shall be prepared in the same orientation and that of the actual strata so that the laboratory test load compresses the soil in die same direction relative to the soil strata as the applied load in the field.
24.Unconfined Compression Test
Unconfined compression test shall be carried out as per 1S:2720 (Part X). The test shall be conducted both on natural and remoulded soil samples. Remoulded specimen shall be prepared by tlie dynamic method of compact ion.
Each unconfined compression test (Natural or Remoulded) shall comprise tests on a minimum of three soil specimens not less than 38mm diameter and a height to diameter ratio of 2, together with the determination of natural moisture content and density. The water content of the specimen. The test results shall be observed and reported as per the standard practice. The tenderer shall quote in the bill of quantities for each confined compression test to include for all the above mentioned items.
25.Triaxial Test
Triaxial tests shall be conducted on the undisturbed samples selected by the Engineer. These tests shall be conducted as per IS:2720 (Pt.XI,XII). Each test shall be conducted on a minimum of three specimens tested at different cell pressures (0.5, 1.0 and 1.5 kg/cm2). The moisture content before and after the test and the density of each specimen shall be determined. The rate inserted in the bill of quantities for the triaxial compression test by the tender shall include for all the above items.
The stress-strain diagrams as well as the Mohr circle envelopes shall be included in the report.
26. Consolidation Test
Consolidation tests shall be conducted on undisturbed samples selected by the Engineer. The co-efficient of consolidation (Cv), the coefficient of volume compressibility (rnv) and compression index (Cc) and the coefficient of permeability (k) shall be determined and reported.
The loading on the test specimens shall be applied in the following stages:
0, 0.1, 0.25, 0.5, 3.0, 1.0, 2.0, 4.0, 8.0 kg/cm2.
Unloading of the test specimens shall be done in suitable stages.
27. Chemical analysis
Chemical analysis of soil and water samples shall be carried out for pH value, sulphate content (SO.), calcium content (Ca) Chloride content (Cl) and total dissolved solids in water.
28. Indian Standard Light Compaction test shall be carried out on Disturbed samples as per IS:2720 (Part VII) to determine moisture density relation and maximum dry density and optimum moisture content shall be reported. The samples for compaction test shall be collected at locations directed by the Engineer and from 0.3m depth below ground level by excavating a suitable size pit.
29. Laboratory CBR Test shall be carried out as per IS:2720 (Part XVI). The sample shall be compacted at optimum moisture content and tested on 4 days soaked samples. The compaction shall be done as per IS. Light Compaction or as directed by the Engineer.
30.On completion of each borehole, three copies of a preliminary borehole log shall be submitted to file Engineer together with cine set of the disturbed samples taken in the borehole.
The preliminary report on logging shall show:
(i)Ground level referred to the available bench or reference mark at site.
(ii)The locations of holes where boring/core drilling operation carried out on a plan.
(iii)The preliminary description of each stratum, joint pattern, rock mass pattern, RQD etc.
(iv)The thickness of each stratum with the boundaries.
(v)The position, type and identification of each sample and site test.
(vi)Any site test results available.
(vii)The levels at which each separate ground water level is first encountered at which it comes to rest (standing water level).
31. Detailed Report
On completion of all field and laboratory testing, a detailed report shall be prepared and submitted to the Engineer. The report shall include (but not by way of limitation) :-
(a)A plan showing the position of all holes where boring/core drilling operation are carried out.
(b)A description of the procedures of investigation and testing employed.