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Trenchless Technology in India — An Overview
Published in S.P. Kaushish, T. Ramamurthy, Tunnelling Asia’2000, 2020
The term microtunnelling is used to describe methods of Horizontal earth boring, which are highly sophisticated laser guided, and remote controlled. These methods permit accurate monitoring and adjusting of the alignment and grades as the work proceeds so that pipe can be installed on precise line and grade. Microtunnelling involves the works for less than 900 mm in diameter however, identical tunnelling equipment is used on larger pipes exceeding 2250 mm (89 inch) in dia. They are called automated tunnel boring machine (TBM). The pipes which may be used are reinforced concrete pipe, vitrified clay pipe, glass reinforcement plastic pipe, fiber glass pipe (Hobbs), ductile iron pipe, steel pipe and asbestos cement pipes. Most microtunnelling equipments are designed to operate in soft-ground soil conditions. It can be used in very difficult ground conditions without expensive de-watering systems or compressed air. Since workers are not required to enter the trenches, it enhances the job safety. The basic process involves hydraulically jacking the pipe into the place, following the microtunnel-boring machine from a bore pit. The bore pit must be structurally stable. All the systems like jacking, steering, mechanical earth pressure counter balance, slurry are controlled at the operation board, which is at the surface of the bore pit. The cutting head is designed to mix the cuttings with the slurry so that the spoil can be removed by pumping through the discharge lines into the slurry separation tank. The pumping pit bye pass unit guides flow and pressure control of the slurry system.
Trenchless Equipment
Published in John E. Schaufelberger, Giovanni C. Migliaccio, Construction Equipment Management, 2019
John E. Schaufelberger, Giovanni C. Migliaccio
Microtunneling is a process that uses a remotely controlled boring machine combined with a pipe-jacking technique to directly install pipe underground. The microtunneling process involves the construction of a launch or jacking pit or shaft and a target or receiving pit or shaft. Shaft or pit dimensions typically range from 8 to 20 feet in length or diameter. A pipe jacking frame or cradle is installed on a level surface (often a concrete slab) in the bottom of the jacking pit, and a concrete thrust block is installed at the back of the pit to provide resistance to the thrust during the pipe-jacking operation. A jacking unit pushes the MTBM forward toward the receiving pit, and the permanent pipe to be installed is jacked in, in 4 to 10-foot lengths, immediately behind the MTBM.
Tunnel construction techniques
Published in David Chapman, Nicole Metje, Alfred Stärk, Introduction to Tunnel Construction, 2017
David Chapman, Nicole Metje, Alfred Stärk
Herrenknecht have combined microtunnelling (as described in Section 5.11) and HDD technology to produce their Direct Pipe® pipe installation method. This technique can be used for installing pipelines under rivers and also for sewer outfalls. The method can install pipes ranging in diameter from 0.8 to 1.5 m and involves using a slurry-based microtunnelling machine attached to a prefabricated pipeline. The microtunnelling machine and prefabricated pipeline attached to the back of the machine are pushed into the ground using a pipe thruster, which has a 5 m stroke length (Figure 5.100). The slurry pipes used to remove the excavated spoil are located inside the prefabricated pipe. The technique only uses one shallow access pit at the start of the drive, with a small reception excavation to retrieve the microtunnelling machine at the end of the drive as the machine arrives close to the ground surface. Since the job site is only based at the starting end of the pipeline, it is a suitable technique for constructing sewer outfalls as the machine can be retrieved from the sea bed at the end of the drive. The method can cope with a range of ground conditions from soft ground to heterogeneous ground and rock.
Evaluating the environmental performance of pipeline construction using systems modelling
Published in Construction Management and Economics, 2020
Mohamed Matar, Hesham Osman, Maged Georgy, Azza Abou-Zeid, Moheeb Elsaid
Microtunneling, in particular, utilizes a miniaturized form of tunnel boring machines (TBMs) that is typically remote controlled to eliminate human work inside the machine itself. Microtunneling has witnessed increasing worldwide market demand since its introduction in Japan in the 1960s. In the US market alone, microtunneling was used to install more than 30,000 km of pipelines over the course of 27 years in sensitive areas where the use of other methods would have caused much higher social and financial costs (Tumbleson 2013, Najafi 2013).