Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. इंटरनेट मानक “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “प0रा1 को छोड न’ 5 तरफ” Jawaharlal Nehru “Step Out From the Old to the New” “जान1 का अ+धकार, जी1 का अ+धकार” Mazdoor Kisan Shakti Sangathan “The Right to Information, The Right to Live” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 10386-11 (2012): Safety Code for Construction, Operation and Maintenance of River Valley Projects, Part 11: Underground Excavation [WRD 21: Safety in Construction, Operation and Maintenance of River Valley Projects]
Transcript
Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.
इंटरनेट मानक
“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru
“Step Out From the Old to the New”
“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan
“The Right to Information, The Right to Live”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
“Invent a New India Using Knowledge”
है”ह”ह
IS 10386-11 (2012): Safety Code for Construction, Operationand Maintenance of River Valley Projects, Part 11:Underground Excavation [WRD 21: Safety in Construction,Operation and Maintenance of River Valley Projects]
SAFETY CODE FOR CONSTRUCTION, OPERATIONAND MAINTENANCE OF RIVER VALLEY
PROJECTSPART 11 UNDERGROUND EXCAVATION
ICS 13.060.50
Safety in Construction, Operation and Maintenance of River Valley Projects Sectional Committee, WRD 21
FOREWORD
This Indian Standard (Part 11) was adopted by the Bureau of Indian Standards, after the draft finalized by theSafety in Construction, Operation and Maintenance of River Valley Projects Sectional Committee had been approvedby the Water Resources Division Council.
With large scale increase in construction activity of river valley projects, the number of major accidents hasincreased. Further, increased construction activity has created certain hazards for persons working on the projects.The degree of safety achieved in project constructions has a direct bearing on the amount of effort expanded toavoid accidents by those who control the conditions and practices on the project. In order to avoid accidents itshould be the overall responsibility of the project authorities to provide measures for the safety of all personsworking on the projects.
There are number of aspects that need to be kept in mind when the safety norms of an entire river valley projectare envisaged. To this end, various aspects that need consideration, from the viewpoint of safety, are dealt with invarious parts of this standard.
The safety code for construction, operation and maintenance of river valley projects is formulated in eleven parts.This part lays down requirements that should be followed with regard to safety aspects during undergroundexcavation.
The following standards may be referred in conjunction to this standard:
IS No./SP Title2379 : 1990 Pipelines — Identification — Colour code (first revision)3016 : 1982 Code of practice for fire precaution in welding and cutting operations (first revision)3696 Safety code of scaffolds and ladders:
(Part 1) : 1987 Scaffolds(Part 2) : 1991 Ladders
3764 : 1992 Code of safety for excavation work (first revision)6922 : 1973 Criteria for safety and design of structures subject to underground blasts10386 Safety code for construction, operation and maintenance of river valley projects:
(Part 2) : 1982 Amenities, protective clothing and equipment(Part 10) : 1983 Storage, handling, detection and safety measures for gases, chemicals and flammable
liquids13115 : 1991 Portable first aid kit for general use — SpecificationSP 22 : 1982 Explanatory handbook on codes for earthquake engineeringSP 70 : 2001 Handbook on construction safety practices
This safety code represents a standard of good practice and takes the form of recommendations. Compliance withit does not confer immunity from relevant legal obligations.
The composition of the Committee responsible for the formulation of this standard is given in Annex A.
For the purpose of deciding whether a particular requirement of this standard is complied with, the final value,observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2 : 1960‘Rules for rounding off numerical values (revised)’. The number of significant places retained in the rounded offvalue should be the same as that of the specified value in this standard.
1
IS 10386 (Part 11) : 2012
Indian Standard
SAFETY CODE FOR CONSTRUCTION, OPERATIONAND MAINTENANCE OF RIVER VALLEY
PROJECTSPART 11 UNDERGROUND EXCAVATION
1 SCOPE
This standard (Part 11) lays down requirements for thesafety aspects to be taken during undergroundexcavation for structures like underground powerhouse, transformer cavern, tunnels, shafts such as surgeshaft, pressure shaft and cable shaft, additionally drivenintermediate tunnels (ADITs) and such other structuresassociated with river valley projects. Safety measuresthat should be followed during their operation andmaintenance are also described.
2 REFERENCES
The standards listed below contain provisions whichthrough reference in this text constitute provisions ofthis standard. At the time of publication, the editionsindicated were valid. All standards are subject torevision and parties to agreements based on thesestandards are encouraged to investigate the possibilityof applying the most recent editions of the standardsindicated below:
1136 : 2008 Preferred sizes for wrought metalproducts (third revision)
1363 Hexagon head bolts, screws and nutsof product grade ‘C’:
(Part 1) : 2002/ Hexagon head bolts (size range M 5ISO 4016 : to M 64) (fourth revision) 1999
(Part 2) : 2002/ Hexagon head screws (size rangeISO 4018 : M 5 to M 64) (fourth revision)1999(Part 3) : 2002/ Hexagon nuts (size range M 5 toISO 4034 : M 64) (fourth revision)
19991786 : 2008 High strength deformed steel bars and
wires for concrete reinforcement —Specification (fourth revision)
IS No. Title
2062 : 2006 Hot rolled low, medium and hightensile structural steel (sixth revision)
2189 : 2008 Selection, installation andmaintenance of automatic firedetection and alarm system — Codeof practice (fourth revision)
2190 : 1992 Selection, installation andmaintenance of first-aid fireextinguishers — Code of practice(third revision)
(Part 1) : 1974 Socketing with zinc (first revision)(Part 2) : 1974 Socketing with white metal (first
revision)(Part 3) : 1994 Socketing with resins
3973 : 1984 Code of practice for the selection,installation and maintenance of wireropes (first revision)
4081 : 1986 Safety code for blasting and relateddrilling operations (first revision)
4138 : 1977 Safety code for working incompressed air (first revision)
4460 (Parts 1 to Gears — Spur and helical gears — 3) : 1995 Calculation of load capacity (first
revision)
2
IS 10386 (Part 11) : 2012
IS No. Title
4756 : 1978 Safety code for tunneling work (firstrevision)
4967 : 1968 Recommendations for seismicinstrumentation for river valleyprojects
5878 (Part 3) : Code of practice for construction of 1972 tunnels: Part 3 Underground
excavation in soft strata7293 : 1974 Safety code for working with
construction machinery10386 Safety code for construction,
operation and maintenance of rivervalley projects:
(Part 3) : 1992 Plant and machinery(Part 4) : 1992 Handling, storage and transportation
of explosives(Part 5) : 1992 Electrical aspects(Part 7) : 1993 Fire safety aspects
12633 : 1989 First filling and emptying of pressuretunnels — Guidelines
14329 : 1995 Malleable iron castings —Specification
14881 : 2001 Method for blast vibrationmonitoring — Guidelines
3 GENERAL SAFETY REQUIREMENTS
3.1 The matter of safety and accident prevention is theresponsibility of personnel on the job and of theorganizations. All persons need to be alert to dangerousconditions and to take necessary precautions for theirown safety as well as that of others working at the site.
3.2 The safety requirement during excavation for anystructure may vary according to the type of structure,type of construction methodology, type of strataencountered and number of men and type of machinerydeployed at site.
3.3 Proper education and organization is necessary forsafety requirements to be implemented in a propermanner. The workmen are required to be made awareof the importance of observing the safety rules (seealso 14).
3.4 The contractor/owner/department/organizationcarrying out the work should employ a safety engineer/manager who should be familiar with all potentialhazards on the job and whose duty would be to educatethe workmen as well as to supervise installation andmaintenance of safety equipment, first aid stations,machinery guards and other safe guards.
3.5 The hazards of going underground are the greatestthe engineer has to face. Underground excavation isalways a dangerous and unpredictable business.Hazards cannot be entirely removed, but can be greatlyreduced by adopting suitable and adequate precautions.
4 INVESTIGATION, DATA AND SURVEYING
4.1 Before proceeding with the work of undergroundexcavation, sufficient knowledge of sub-surface stratais essential. Insufficient geological data will not onlylead to delay in completion of work and increase incost, but is also of great concern to safety. Geologicalsurprises are to be anticipated and adequate measuresfor such eventualities should be made available inadvance. Planning of underground hydropower projectsand tunnels should be based on sufficient geotechnicalaspects. This will form the basis of excavation and rocksupport, etc. Latest advancements should be taken into consideration.
4.2 Details of geological strata using mapping methodssupplemented by exploratory drilling to establish fissuresystems, faults, folds, etc, are essential. The finalgeological map should provide information on theextent of soil and rock formation, zones of weakness,the dip and strike, etc, of the strata.
4.3 Adequate measures such as forepoling, pre-grouting, etc, should be taken for any geotechnicalproblems in case of blind/unexplored geologicalregions.
4.4 Latest available data from codes and outputs ofnearby seismic stations should also be considered fordesign of underground structures (see IS 4967). Actualdata obtained from a nearby strong motion network ormicro seismic telemetry network should be consideredin seismically active areas/region, if necessary.
5 DESIGN DATA
5.1 Excavation size is a key parameter in the stabilityof underground openings in rock and the larger theexcavation, the less stable the roof behaviour. Theprinciple objective in the design of a support system isto help the rock mass to support itself. The use of rockbolts helps to form homogeneity in rock mass. The useof rock bolts is a flexible method that can be combinedwith wire-mesh, shotcrete and concrete lining to copewith most situations encountered during undergroundexcavation (see 6.7).
5.2 A professional engineer should be engaged forpreparation of design and drawings. Due considerationin design process should be given for the experiencegained in underground works of nearby areas. Fielddesign and changes should be documented and vettedby a competent engineering person.
6 DRILLING AND BLASTING OPERATIONS
6.1 Handling Explosives
During blasting operation proper precautions should betaken for the protection of persons, work and property.
3
IS 10386 (Part 11) : 2012
All government laws and regulations relating to thedesign and location of the explosive magazines, thetransportation and the handling of explosives and othermeasures evolved for the prevention of accidents shouldbe strictly observed. Warning sign should be displayedon the magazines and warning signal should be givenfor each blast. Explosive should be stored in a safe placeat a sufficient distance from the work site and under thespecial care of a watchman [see IS 10386 (Part 4)].
IS 10386 (Part 4) for handling, transportation andstorage of explosives, IS 4081 for blasting and relatedoperations and IS 4138 for working in compressed air,should be strictly adhered to in this regard. Copies ofthe above standards should be widely circulated andkept available at site office.
6.1.1 Whenever blasting operation is to be conducted,workmen/supervisors should be kept at sufficientdistance in a safe shelter/pocket. Left over and un-blasted detonators should be removed safely. It is to beensured that no un-blasted detonators are left over inthe area before next operations starts. If the hole drilledfor blasting is damp, the junction of the fuse anddetonators should be made water tight by means oftough grease, white lead or tar. Proper insulated wireshould be used for blasting to be carried out by electricaldetonators. Only electric blasting should be resortedto in all underground works.
6.1.2 Precautions Against Lightning
a) Necessary safety measures should be taken inorder to provide protection from direct strokelightning and secondary action of thelightning.
b) During a thunderstorm, no blasting operationincluding charging should be carried out. If incase of electrical shot-firing, the firing circuithas to be set-up before thunderstorm appearsand the blast lines should be disconnected fromthe trunk line and thoroughly insulated withtape. At the same time, all persons must bewithdrawn from the danger zone.
6.2 Blast Vibration Monitoring
Monitoring the vibrations caused by undergroundblasting plays a vital role since they induce transient orvibratory displacements which could be permanent (seeIS 14881).
6.2.1 Preliminary and detailed surveys should be carriedout as per standard practices with modern instruments.During execution of work, accuracy should be maintainedin alignment, length and breadth, and levels, etc.
6.2.2 Tunnel excavation may generate subsidence ordeformation around the structure causing enhanced stresslevels. The safety of the existing structures may also be
endangered. Special consideration on the safety aspectsshould be taken in the design/execution. Execution ofearth tunnels/tunnels through soft strata poses a greathazard. Earth tunnels/tunnels through soft strata shouldbe executed mainly during non-rainy season. Supportsystem and drilling operation should be formulated withextra care and caution [see IS 5878 (Part 3)].
6.2.3 Tunnel face stability is a severe problem whiletunneling, especially in non-cohesive strata. Buildingsand services over the excavation and the workers insidethe tunnel are under continuous risk due to this problem.There may be sudden falls of soil, creating large cave-ins up to the surface. Falling material could endangerworkers. Such endangered areas should be supported,barricaded or effectively guarded.
6.2.4 Safety of tunnel entry near portal with less rockcover should be taken care of during the investigation/design stage itself. Normally the soil cover should betwice the diameter of the tunnel. If the overburden isless than twice the diameter, then cut and cover systemshould be adopted. Necessary concrete cover at thecrown as well as the sides with anchor rods, if necessary,should be provided at least for 30 m from the portal.
6.2.5 The arrangement of underground power houseand transformer caverns are normally planned adjacentto each other and it should be ensured that there isenough lateral rock cover in-between them for thestability of both the cavities based on the rock masscharacteristics.
6.3 Rock Bursting
The energy within the rock, as inherent stresses beginto relax on excavation, can be enormous and powerfulenough to expel large chunks of rock causing rock burst/spalling. There are various methods for determiningthe rock pressure for support design of undergroundexcavation which should be utilized.
6.4 Excavation Slope
The slopes in the underground excavation such aspressure shafts, etc, should be decided on suitableengineering practice based on the geological strata, geo-techniques and geo-physical data.
6.4.1 Sequence of Excavation
Sequence of excavation should be carefully planned,specifying the charge and strength of explosives. Wheremultiple work fronts/junctions exist involving crossingover of components, abundant care should be exercizedin blasting operation and mucking and guiding thevehicles/equipment.
6.5 Excavated Earth/Muck
6.5.1 Excavated muck should be cleared as soon as the
4
IS 10386 (Part 11) : 2012
excavation process of each cycle is completed and de-fuming has been done. The free falling muck in thepressure shafts should be removed as frequently aspossible, otherwise it may choke up the shafts. Chokingof the lower end of the shaft may cause the muckingoperations to prove hazardous to the mucking crew andthe equipment.
After the blasting and before mucking is started, thepollution should be checked on face of mucking as perrelevant Indian Standards. Radioactive pollution, if any,should be checked for permissible limits.
6.5.2 No inflammable materials or oil and grease shouldbe stored inside or near the tunnels or shafts and allcombustible rubbish from the tunnel or shaft should bepromptly removed.
6.6 Overhangs
6.6.1 Overhangs in the excavated face are hazardousas these may come down unexpectedly and result infatal accidents to persons working at lower levels.Hence, such overhangs should be removed beforecontinuation of further work in that area. Adequateprecautions should be taken while removing theoverhangs.
6.6.2 All excavated faces, on which work is in progressor work is temporarily suspended, should be maintainedor left at safe slopes, so that the danger caused by cavingor sliding is eliminated.
6.7 Rock Bolts
6.7.1 Material
Rock bolts should not be less than 25 mm diameter.Rock bolt should generally have a tensile strength inthe range of 540 N/mm2 to 590 N/mm2, a minimumyield point of 490 N/mm2, a minimum elongation of12 percent and should be threaded with rolled threadsfor at least 200 mm length at both ends. However, thesevalues should be checked with reference to the rockstrata/type of rock, which may be ascertained by fieldtests and rock property analysis.
The Indian Standards given below should be referredto:
a) High strength steel deformed : IS 1786bars
b) Black hexagonal bolts, nuts, : IS 1363lock nuts and black hexagon (Parts 1screws to 3)
c) Expansion anchors — Black : IS 14329hearth malleable iron casing
d) Washers/Bearings — Structural : IS 2062
steel
e) Plug — Carbon steel casting : IS 1030
6.7.2 Pullout Test
Rock bolts should be tested at intervals as deemed fit.They should be subjected to at least 2 percent testing,prior to grouting the bolts.
6.7.3 Rock Bolt Protection
To avoid possible corrosion the rock bolts should beprotected by means of hot dip galvanizing, zincphosphating or epoxy powder coating, for longer life.
6.8 Instrumentation
6.8.1 General
Any underground excavation for construction of powerhouses, transformer cavern, cable shaft, ventilationshaft, surge shaft, etc, is subjected to three dimensionalstress, which becomes two dimensional inside thesurface of cavity causing readjustment of stresses inand around the cavity. As stress is related to strain,release of stress results in displacements. Displacementsalso occur due to the opening of cracks on the faultzone or jointed rock. When the rock around excavatedcavity is good, then the cavity should be designed asself supporting. Otherwise suitable supports should beprovided. Instrumentation is helpful for assessing thequality of rock, monitoring the behaviour of rock massaround openings and also monitoring performance ofsupporting measures, strengthening/safetyarrangements during the life of the structures.
6.8.2 Instrumentation Programme
6.8.2.1 During construction/underground excavation
a) To verify the hypothesis and assumption ofdesign;
b) To monitor safety during construction/underground excavation;
c) To measure change in parameters duringunderground excavation/construction; and
d) To verify the performance of the undergroundexcavation/construction.
6.8.2.2 After construction
a) Performance monitoring for safety during thelife of the structure;
b) Evaluation of effect, during operationalcondition, on parameters like stress, strain,water pressure, inclination, deflection andwater seepage, etc; and
c) Comparison of observations with designassumptions.
6.8.3 Recommended Instruments
Instruments like strain gauge/meters/load cell,extensometer and piezometer conforming to relevant
5
IS 10386 (Part 11) : 2012
Indian Standards should be provided as perrecommendations of the instrumentation engineer andinstrument manufacturers. Typical instrumentationscheme is shown in Fig. 1.
6.8.4 Automatic Data Acquisition System/Station
The data acquisition station should be located in anarea near to measuring point and out of hindrance areaand should be easily accessible. Readings should be
FIG. 1 TYPICAL INSTRUMENTATION SCHEME
6
IS 10386 (Part 11) : 2012
recorded systematically in a data acquisition systemfor monitoring.
6.8.5 Data Processing
The readings should be processed, reduced, plotted andthe values obtained should be interpreted duringexcavation stage as well as after completion stage.Interpretation of values should be done to ascertain thenecessity of additional strengthening measures such asprovision of additional rock bolt, shotcreteing, etc, to actas permanent supports for the underground excavation.
6.9 Service Lines
Service lines such as power cable, water line, air line,dewatering line, etc, of the owner and contractor, shouldbe segregated and laid/run on opposite face of thetunnel/cavern.
6.9.1 Power Lines
Live wires and cables are laid in the area of excavationfor blasting operations, drilling of holes and otheroperations involving the use of electric power. Wheresuch cables are laid, care should be taken to see thatthese cables are not laid haphazardly. The supervisors,foreman and the construction staff should ensure thatworkmen or visitors are kept away from live wires.Wherever necessary, warning signals should be posted.Cables which are cut or open should be promptlyreplaced [see IS 10386 (Part 5)]. All electric wiringshould be properly insulated and of sufficient capacitysupported on insulators of approved type and notlooped on or tied to spikes, ventilating pipes, or othermakeshift supports. All switches should be of automatictrip type. Lines should be located so as not to createany electricity or tripping hazard to workers.
6.9.2 Water Lines
Water lines are laid for different purposes such asdrinking water, fire fighting, construction purpose, etc.Each line should be properly distinguished by a systemof colour coding as per the relevant Indian Standardsand should be well maintained.
6.10 Lighting, Warning Signals, etc
6.10.1 Adequate lighting arrangements should beprovided at the underground excavation worksite in theaccess tunnel, ADITs (Additionally Driven IntermediateTunnels), pathways.
6.10.2 Danger lights should be provided at machinerylocations and turning points in the access path forguidance of transport vehicles. At bend/crossings ofpathways/roadway proper indications should bedisplayed.
6.10.3 Whenever a workman is required to climb up/down on an excavation slope for working on shuttering,
reinforcement at shafts, inclined tunnels, etc, he shoulddo so with a safety rope tied securely to a safety beltand wearing safety helmet. Safety net should beprovided below the work spot.
6.10.4 Single person should not be permitted in the areaof underground excavation alone. All entry and exitsthat is, check-in and check-out times should be recorded.
6.11 Dewatering
6.11.1 During excavation work, adequate arrangementsshould be provided for dewatering and bailing out ofwater from the excavated area to prevent slipperysurfaces and sliding of slopes due to standing water.
6.11.2 Adequate measures should be taken to drainaway the water from the upper surfaces of excavatedslopes or benches. This prevents saturation of soil whichcould result in slips of the excavated slopes.
6.11.3 Temporary drainage system as well as permanentones, such as ducts, should be constructed.
6.11.4 Necessary full-proof reliable arrangementsshould be made so that the surface/storm water fromvalleys near by tunnels, shafts, additionally drivenintermediate tunnel (ADIT), etc, do not gain entry intothe work area. In pumped storage power houses thereis always a threat of flooding if there is leakage ordamage to the draft tube gate. Pumps alone may not beable to pump up the water and provision of drainagetunnels to nearby valleys should be considered.
6.11.5 Drainage holes should be provided in the crown,as well as on either side of the cavern, shafts, etc, so thatthe seepage water can be drained through these holes.
6.11.6 Following measures should be taken wheneveradverse geo-thermal conditions are encountered duringunderground excavation.
a) Monitoring of temperature inside the tunnelespecially where rock cover is very high andwhere there is history or evidence ofoccurrence of hot water springs;
b) Provision of additional ventilation includingblowing of cool air, etc, at work site;
c) Provision of ice-jackets to workers; andd) Reduced working hours inside the cavern.
6.12 Ventilating the Tunnel
a) Ventilating duct/pipe of suitable diameter asper approved norms should be provided insidethe tunnel for diffusing the fumes afterblasting.
b) In addition to the ventilating pipe, a sufficientsupply of fresh air should be provided at alltimes, in all places underground and provision
7
IS 10386 (Part 11) : 2012
should be made for quick removal of toxicgases and dust.
c) The concentration of various gases inside thetunnel should adhere to the limits givenin 7.2.2 of IS 4756.
6.13 Noise Control
The noise pollution should be controlled,
a) at the source;b) by enclosure;c) by sound absorbing materials; andd) by ear protection.
Control of noise by ear protection should be effectedby the following methods depending upon the soundintensity level of the noise:
a) Cotton;b) Impregnated cotton;c) Soft rubber;d) Muffs and helmets; ande) Any of the above combinations.
6.14 Welding
Welding equipment and the structure to be weldedshould be properly earthed. General exhaust systemshould be available to take care of the evacuation offumes. Unused gas cylinders should be kept at a safeplace.
6.15 Winch/Wire Rope
Winch is an important equipment which conveys menand material. It should be operated and maintained withextreme care and caution. Periodical checks for the wirerope, gear box, braking system etc, should be carriedout as per relevant standards.
Inspection of the wire rope system should be carriedout as frequently as possible to locate any kinking,twisting of rope, loosening of the strands and any otherdamage. Obstruction in the movement of the rope/wiresshould be eliminated to avoid accident.
Log books should be maintained properly recordinghours of operation, details of trips, number of men andload carried, problems noticed, repairs carried out,periodical inspections, mandatory checks andmaintenance works.
There should not be any overlapping of wire ropes inthe winch drums which may lead to sudden fall/jerk ofthe winch/jula in the shaft. This sudden jerk of winchmay hit the side rock in the case of small diameter shaftssuch as power cable shaft, ventilation shafts leading toserious accidents. Comparatively, confined spacecreates a hazard.
The relevant Indian Standards mentioned below shouldbe referred to:
a) Steel-wire rope : IS 2266b) Maintenance of wire rope : IS 3973
c) Preferred size for wrought : IS 1136metal products (trolley
wheels)
d) Gears : IS 2458,IS 2467,IS 2535 (Part 1),IS 2535 (Part 2)and IS 4460(Parts 1 to 3)
e) Motor : IS 325
f) Socketing of wire rope with: IS 3937 (Parts 1molten metal to 3)
6.16 Tools, Plant and Machinery
Proper care should be taken in the operation andmaintenance of transport vehicles such as loaders,dumpers, tippers and trailers, cranes/winches.
Numbers of serious accidents have been associated withtransport. The use of trucks/wagons and heavymachinery should be done under the supervision ofexperienced personnel. Care should be exercised whenguiding vehicles for loading so that they don’t collidewith side cutting and other vital installations such ascables, lights, ventilation ducts, pumps etc. Vehiclepockets should be provided at suitable intervals (sayevery 750 m) along the tunnel.
The underground excavation of inclined shaft isnormally done by raise climber or similar machine.Great care should be taken in the operation andmaintenance of such machine [see IS 10386 (Part 3)and IS 7293].
6.17 Access and Escape Ways
6.17.1 Pathways, if required, should be non-slipperyand of adequate width. They should be strong enoughto withstand the movement of workers and hand carriedtools and equipment.
6.17.2 Gangways, if required, should be strong and ofproper construction. Planks used should be of uniformand sufficient thickness and free from knots. Gangwaysshould be kept clear of excavated materials or otherobstruction.
6.17.3 Proper level steps should be provided where thegradient of roadway exceeds 15°. It is desirable thatproper steps be provided in wet and/or slipperyroadways, irrespective of the gradient of such roadways,so that the workers can conveniently use protectivefootwear even under adverse conditions.
8
IS 10386 (Part 11) : 2012
6.17.4 Escape routes from different sections or partsof underground power house, underground transformercavern, tunnels, etc, should be prominently designatedby suitable markings so that they are clearly visibleunderground. This is in addition to the usual mock drills/rehearsals once in a quarter.
7 TUNNEL WATERPROOFING
One of the most persistent problems encountered bothduring construction and the operation of any tunnel isthat of water leakage/seepage.
Primary and secondary linings are the main defenceagainst water ingress or leakage but these can beweakened by a faulty method. Grouting techniques andgrout composition have become extremelysophisticated during the past few years with thedevelopment of modern injection techniques as wellas the growing use of additives such as resins andplasticizers and these should be considered for useappropriately.
8 WATER CONDUCTOR SYSTEM — SAFEFILLING AND EMPTYING
During these operations, the stresses in surroundingrock mass of water conductor system gets increased,released or rearranged. These are critical operationsinvolving high risk and due processes. Safeguardsshould be followed as detailed in IS 12633.
9 FAILURES
In certain sections, although the supports are providedas per the rock conditions as stated by the designers,failure of roof and side walls may occur in the form offalling blocks, roof cave-in, crown settlement, bucklingof ribs, shotcrete cracking, etc. The possible causes offailure in certain sections could be due to the following:
a) Assumption of improper classification of therock by the wrong choice of support foridentified rock class;
b) Insufficient thickness of applied shotcretelayer;
c) Incorrect rock bolting pattern and/orinsufficient number of rock bolts;
d) Shotcreting applied after considerable delaythat is after loosening of surrounding rockmass, insufficient shotcrete in crown, initiallayer of shotcrete omitted;
e) Steel supports not positioned properly and nobackfilling behind the steel support;
f) Non-identification of rock blocks/wedgeswhich are free to fall or free to slide undertheir own weight;
g) Failure to insert rock bolts to stabilize the rock
blocks which are likely to fall;h) Additional layer of shotcrete omitted in weak
ground; and
j) Incorrect grouting of rock bolts and un-tensioned rock bolts.
10 EMERGENCY PLANNING
10.1 Workers at the face of a long tunnel are deprived ofquick access to a medical center. For this, each memberof the work force should be given at least some basicfirst-aid training. A special team of highly trainedadvanced first aiders is also essential. They should beprovided with first-aid kits. Presence of doctors in projectarea is also important. Safety officers, with a mines safetybackground, should inspect machinery, monitor forhazards and give regular instruction on safe methods.
When there is a fatality or serious untoward incident,each such occurrence should be thoroughly investigatedand the management should decide on how to deal withsuch situation and to avoid recurrence of a similarincident. It is essential for immediate shut down andexamination of machinery and all similar equipmentinvolved.
In case of major accidents, it is also necessary to informimmediately various levels of management, near bydisaster management agency, in addition to fire andrescue team. The respective contact numbers shouldbe readily available and displayed. Review meetingsshould be held as frequently as possible to sort out andplan for any shortcoming.
10.2 Means of Exit/Escape
During excavation work, adequate means of exit/escapefor work force from the hazardous areas/situationsshould be planned, and kept clear.
10.3 Evacuation Plan
Suitable evacuation plan, should be planned and madeknown to all the personnel involved in undergroundexcavation work.
10.4 Communication
Reliable communication system should be maintainedduring and after excavation work. It is desirable to haveloud phones or megaphones readily available forannouncement of any impending emergency like fire,collapse, etc.
11 HEALTH AND SAFETY
Supervisory health and safety course should beconducted and attended by engineers/supervisor/foremen. Written check lists should be displayed at allwork locations for compliance.
9
IS 10386 (Part 11) : 2012
The rescue team should be highly trained and wellequipped. Proper personal protective equipment shouldbe made available to operators. The level of dieselfumes within underground excavation area should beclosely monitored by gas analyzer.
12 PERIODIC INSPECTION
Periodic inspection of underground excavation areasafter commissioning of power house plays a vital roleand should be made mandatory specifying periodicity.Necessary periodic maintenance of ladders, landingplatforms, top cover grills of various shafts, lining intunnels, winches for shafts, etc, are very important inthe long run. Vegetation growth in the unlined shafts,etc, should be completely cleared. After commissioning,the tunnels, shafts, underground power house andtransformer cavern side walls, roof, etc, should beperiodically inspected and repairs attended toimmediately during shut down period, etc.
13 COMMUNICATION
Proper communication system should be establishedto facilitate communication between workplace and themanagement, worker and the safety manager andbetween various work fronts. Walky-talkie, wirelessmike system and similar equipment should be installed.Close circuit TV should also be installed to keep watchof critical components, critical locations, auxiliaries,cable routes, transformer cavern, and other vulnerableareas.
14 SAFETY OFFICER
It is essential to employ a qualified safety officer/engineer-in-charge to supervise the safety measures andto ensure the safety of personnel, employees, workersemployed at site of underground excavation,equipments, during the excavation, operation andmaintenance period also.
The duties of the safety engineer/manager/officer aregiven below:
a) To impart education and training to theworkers and employees engaged in theunderground excavation works;
b) To comply with relevant safety rules andregulations;
c) To undertake all steps to reduce risk toemployees, property, machine, andsurrounding areas;
d) To check all machine, equipment, fire fightingwater piping system, electrical appliances,first-aid station and to keep them in goodworking condition;
e) To take immediate action during anyemergency situation, floods, etc;
f) Sustaining the efforts and continualimprovements;
g) To evolve safety planning and conduct reviewmeeting with site management, contractorsand workers;
h) To arrange for displaying the warning signals/boards at vulnerable area;
j) To avoid excessively and unnecessarystrenuous work position and movement;
k) To conduct internal safety audit half yearly/annually, and to conduct external safety audittwice or thrice during the excavation process;
m) To prepare safety manuals for each specificcomponent; and
n) To ensure mandatory inspection and complianceand monitoring at higher management levels.
14.1 Accident Reporting
Any accident fatal/non-fatal (injuries) should bereported to the top management and law enforcingauthorities within a time frame as below:
Reporting time :
Fatal : Immediate (detailed report shouldfollow)
Non-fatal : within 3 daysDamage to : within 2 days (preliminary report)costly and detailed report after dueequipment inspection of experts and assessment
14.2 Cause for Accidents
Cause for accident should be reviewed/investigated andremedial measures monitored. Necessary safetymeasures should be adopted. Existing measures, iffound deficient, should be modified and corrected andsuitable guidelines should be issued, to avoidreoccurrence.
14.3 Disaster Management
Close co-ordination should be maintained with thedistrict disaster management cell at all times especiallyat the aftermath of occurrence of fatal accidents, floods,fire, epidemics and other natural calamities.
15 FIRE RISK
15.1 Smoking by workers increases the risk of fire.Smoking should be strictly prohibited in work spot.Cooking in and around the vicinity of work place shouldbe prohibited. As there is danger of fire and smokeresulting from rubbish, litter during constructionoperations, they should be removed and taken out inevery shift. Safety code for electrical aspects [IS 10386(Part 5)] and for fire safety [IS 10386 (Part 7)] shouldbe adhered to.
10
IS 10386 (Part 11) : 2012
15.2 Fire Alarm/Smoke Detection Alarm System
After excavation work, vulnerable areas in the tunnelshould be provided with automatic fire detection andalarm system (including manual fire alarm call points)conforming to IS 2189.
15.3 Extinguishers
Fire extinguishers, of various types suitable for the areasof fire risk covered should be provided in conformitywith IS 2190.
16 VISITORS
Visitors should not be permitted to enter the area ofunderground excavation. In unavoidable cases, theyshould be accompanied by a supervisor. They shouldbe kept at sufficient distance from the cutting edge,running machinery and other potentially dangerousareas. All visitors should be provided with safetygadgets, and their details noted in the entry register.
Details of all persons including workers/supervisors,their time of entry into the site and exit should berecorded.
17 BUDGET
As the safety aspects of underground structures are ofparamount concern to the nation/state/owner, the safetysystem should be kept alert and reliable and areasonable budget provision should be allocated,especially during the maintenance period.
18 DOCUMENTATION
Proper documents should be prepared indicatingproblems encountered during the excavation works,such as accidents, flooding, rock fall, if any, and otherdifficulties encountered during excavation etc. Theoutcome and action taken on periodic inspectionsshould also be documented. This document will beuseful for future underground excavation works.
11
IS 10386 (Part 11) : 2012
ANNEX A(Foreword)
COMMITTEE COMPOSITION
Safety in Construction, Operation and Maintenance of River Valley Projects Sectional Committee, WRD 21
Organization Representative(s)
NTPC Ltd, New Delhi EXECUTIVE DIRECTOR (HYDRO-ENGINEERING) (Chairman)
Bhakra Beas Management Board, Chandigarh MEMBER (IRRIGATION)DIRECTOR (DAM SAFETY) (Alternate)
Central Board of Irrigation & Power, New Delhi SHRI A. C. GUPTA
SHRI N. K. BHATIA (Alternate)
Central Electricity Authority, New Delhi SHRI R. K. RUSTAGI
Central Water Commission, New Delhi DIRECTOR (DSM)DIRECTOR (DSR) (Alternate)
Geological Survey of India, Kolkata SHRI D. N. BHATTACHARYA
SHRI C. PAUL (Alternate)
Indian Institute of Technology, Roorkee DR GOPAL CHAUHAN
Irrigation Department, Government of Kerala, Thirunvanthapuram CHIEF ENGINEER (IDRB)DIRECTOR (DESIGNS, IDRB) (Alternate)
Irrigation & CAD Department, Government of Andhra Pradesh, SHRI I. S. N. RAJU
Hyderabad SHRI S. PANDURANGA RAO (Alternate)
Irrigation Department, Government of Punjab, Chandigarh CHIEF ENGINER (RSDD)DIRECTOR DAMS (RSDD) (Alternate)
Irrigation Department, Government of Uttarakhand, Dehradun CHIEF ENGINEER (GANGA VALLEY)SUPERINTENDING ENGINEER (MB DAM) (Alternate)
Jaiprakash Industries Ltd, New Delhi SHRI D. G. KADKADE
National Projects Construction Corporation Limited, Faridabad SHRI S. BASAK
SHRI A. K. GUPTA (Alternate)
North Eastern Electric Power Corporation Ltd, Shillong SHRI S. R. NATH
SHRI A. K. DAM (Alternate)
Saradar Sarovar Narmada Nigam Ltd, Gandhi Nagar EXECUTIVE DIRECTOR (D&P)
Satluj Jal Vidyut Nigam, Shimla SHRI R. K. SHARMA
SHRI V. S. UPADHYAYA (Alternate)
Tamil Nadu Electricity Board, Chennai SHRI K. GOPAL
SHRI V. GOPALAKRISHNAN (Alternate)
Tehri Hydro Development Corporation Ltd, Rishikesh SHRI R. K. VISHNOI
SHRI MANOJ SARDANA (Alternate)
Tungabhadra Steel Products Ltd, Tungabhadra Dam SHRI HUSSAIN BIN ALI
SHRI Y. S. CHANDRA SHEKAR (Alternate)
Water Resources Department, Government of Madhya Pradesh, Bhopal SHRI K. K. TIWARI
SHRI R. K. JAIN (Alternate)
In personal capacity (Venmala Cochin-682028) SHRI G. B. MENON
BIS Directorate General SHRI J. C. ARORA, Scientist F & Head (WRD)[Representing Director General (Ex-officio)]
Member SecretarySHRI R. R. DASH
Scientist C (WRD), BIS
Bureau of Indian Standards
BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goodsand attending to connected matters in the country.
Copyright
BIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publications), BIS.
Review of Indian Standards
Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of‘BIS Catalogue’ and ‘Standards : Monthly Additions’.
This Indian Standard has been developed from Doc No.: WRD 21 (463).
Amendments Issued Since Publication
Amend No. Date of Issue Text Affected
BUREAU OF INDIAN STANDARDS
Headquarters:
Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002Telephones : 2323 0131, 2323 3375, 2323 9402 Website: www.bis.org.in
Regional Offices: Telephones
Central : Manak Bhavan, 9 Bahadur Shah Zafar Marg 2323 7617NEW DELHI 110002 2323 3841
Eastern : 1/14 C.I.T. Scheme VII M, V. I. P. Road, Kankurgachi 2337 8499, 2337 8561KOLKATA 700054 2337 8626, 2337 9120
