Search results
Results from the WOW.Com Content Network
A tunnel boring machine (TBM), also known as a "mole" or a "worm", is a machine used to excavate tunnels. Tunnels are excavated through hard rock, wet or dry soil, or sand , each of which requires specialized technology.
It is a rapidly growing sector of the construction and civil engineering industry. It can be defined as "a family of methods, materials, and equipment capable of being used for the installation of new or replacement or rehabilitation of existing underground infrastructure with minimal disruption to surface traffic, business, and other activities."
Construction site and equipment prepared for start of work in Cologne, Germany (2017) Construction is a general term meaning the art and science of forming objects, systems, or organizations. [1] It comes from the Latin word constructio (from com-"together" and struere "to pile up") and Old French construction. [2]
A rotating cutting wheel is located at the front end of the shield. Behind the cutting wheel there is a chamber where the excavated soil is either mixed with slurry (so-called slurry TBM) or left as-is (earth pressure balance or EPB shield), depending on the type of the TBM. The choice of TBM type depends on the soil conditions.
Tunnel Construction. Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management.
The new Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method [1] (SCL), is a method of modern tunnel design and construction employing sophisticated monitoring to optimize various wall reinforcement techniques based on the type of rock encountered as tunneling progresses.
Traditionally, construction has made use of manual labor such as tradesmen and subcontractors for tasks such as the installation of prefabricated elements. [6] In the industrialization phase, construction uses manufacturing processes and technology to perform off-site prefabrication, assembling building components off-site rather than at the point of installation.
Time and materials (T&M) is a standard phrase in a contract for construction, product development, or any other piece of work in which the employer agrees to pay the contractor based upon the time spent by the contractor's employees and the subcontractors' employees to perform the work, and for materials used in the construction, plus the contractor's markup on the materials used, no matter ...