Posts by Kanwarjot Singh

In segmental tunneling, the jacks are installed at the shield so that it is not necessary to install thrust wall at the jacking pit. This provides the opportunity for smaller size of the pit because of the absence of thrust wall. Moreover, as the jacking operation involves the jacking of small length of segmental liner plates and hence smaller force would be required for pipe jacking when compared with traditional pipe jacking (jacks at jacking pits) where the jacking force is needed to overcome long lengths of pipe drives. On the other hand, the use of segmental tunneling offers better control in alignment because the steering operation could be performed at the shield.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

By
Kaushal kishore
Materials Engineer, Roorkee

The scarcity and availability at reasonable rates of sand and aggregate are now giving anxiety to the construction industry. Over years, deforestation and extraction of natural aggregates from river beds, lakes and other water bodies have resulted in huge environmental problems. Erosion of the existing topography usually results in flooding and landslides. Moreover, the filtration of rain water achieved by deposits of natural sand is being lost, thereby causing contamination of water reserves used for human consumption. Hence, to prevent pollution authorities are imposing more and more stringent restrictions on the extraction of natural aggregates and its crushing. The best way to overcome this problem is to find alternate aggregates for construction in place of conventional natural aggregates. Rubber aggregates from discarded tyre rubber in sizes 20-10 mm, 10-4.75 mm and 4.75 mm down can be partially replaced natural aggregates in cement concrete construction.

About one crore 10 lakhs all types of new vehicles are added each year to the Indian roads. The increase of about three crores discarded tyres each year pose a potential threat to the environment. New tyre is made of natural rubber (also called virgin rubber), styrene-Butadien Rubber (SBR), Polybutadienc Rubber (PBR), Carbon black, Nylon tyre cord, rubber chemicals, steel tyre card and Butyl rubber.
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Following are the IS codes which are used for Clay and Stabilized Soil products for Construction. It includes standardization in the field of burnt, unburnt clay and stabilized soil products for construction.

IS 654:1992 Clay roofing tiles, mangalore pattern – Specification.

IS 1077:1992 Common burnt clay building bricks – Specification

IS 1464:1992 Clay ridge and ceiling tiles – Specification

IS 1478:1992 Clay flooring tile – Specification

IS 1725:1982 Specification for soil based blocks used in general building construction

IS 2117:1991 Guide for manufacture of hand-made common burnt clay building bricks
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Following are the IS codes which are used for Construction Management including safety in construction. It also includes planning and organization at site for residential buildings, public buildings and offices, and industrial buildings, formulation of standards laying down safety requirements in the various operations involved in different types of civil engineering construction.

IS 3696(Part 1):1987 Safety code of scaffolds and ladders: Part 1

IS 3696(Part 2):1991 Safety code of scaffolds and ladders: Part 2

IS 3764:1992 Code of safety for excavation work

IS 4014(Part 2):1967 Code of practice for steel tubular scaffolding: Part 2 Safety regulations for scaffolding

IS 4081:1986 Safety code for blasting and related drilling operations
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Following are the IS codes which are used for standardization in the Public Health Engineering including standardization in the field of water supply, drainage and sanitation in buildings, including laying of pipelines, small sewage treatment plants, ancillary structures for water supply and sewerage and standardization of equipment used in public health engineering including their design, manufacture, testing, operation and maintenance

IS 1172:1993 Code of basic requirements for water supply,drainage and sanitation

IS 1742:1983 Code of practice for building drainage

IS 2064:1993 Code of practice for selection, installation and maintenance of sanitary appliances

IS 2065:1983 Code of practice for water supply in buildings

IS 2470(Part 1):1985 Code of practice for installation of septic tanks: Part I design, criteria and construction
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It is commonly recognized that ground settlement is one of the major concern in pipe jacking operation. However, engineer should also pay attention to the problem of ground heaving during grouting work of pipe-jacking. For instance, if excessive slurry or grout pressure is applied so as to exceed the overburden pressure, ground heaving would result. Alternatively, if the ground contains loose soils with high porosity, the same phenomenon also occurs. Proper control on the applied pressure and viscosity of grout/slurry is necessary to prevent such occurrence.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

It is reported by Lake (1992) that settlements are expected at the ground surface at a distance of 1-2 times of tunnel depth ahead of the tunnel face and 80% to 90% of settlement to be completed at a similar distance behind the face. However, in the paper “Monitoring of ground response associated with pipe jacking works – recent experience in Hong Kong”, the author pointed out that based on their experience, development of longitudinal settlement was observed at a distance of 3-4 times of tunnel depth behind the tunnel face and little settlements were reported immediately above the tunneling face.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

When the pipejacking machine moves from a region of soil to very hard rock, it will be subject to damage of cutting disc. To break and loosen the rock, the pipejacking machine applies a large torque on cutting wheels.

However, with the change of soft region to hard region, the pipejacking machine is still under the same jacking load. As such, this results in insufficient or little space for the movement of the machine against the rock face, leading to damage and exhaustion of the pipejacking machine.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

The rate of cutting through soils is faster than that of cutting through boulders for pipe-jacking machine. As such, when pipe-jacking machine enters a region of mixed ground with soils and boulders, the machine has the tendency to move towards the direction of soft soils because of the difference of rate of advancement of pipe-jacking machine for soils and boulders. Consequently, migration of soft soils occur which contributes to ground settlement. The degree of settlement is dependent of the depth of soil cover, soil property and the size of boulders.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

When the process of pipe jacking stops, building up of resistance is very fast in some soil. For instance, increase in jacking force of 20%-40% is required for a stoppage of pipe jacking for just several hours. Hence, it is recommended that pipe jacking should be carried out in a continuous operation.

For a long pipeline, the frictional forces established between the jacking pipes and soil is high. Sometimes, such resisting forces may be so high that they can hardly be overcome by the jacks in jacking pits. Moreover, even if the jacks can overcome the high frictional forces induced during jacking, high loads are experienced in jacking pipes during driving. Jacking pipe’s material e.g. concrete may not have sufficient strength to resist these stresses and hence pipe strength is another factor that governs the need for consideration of using intermediate jacks.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.