Abstract Considering that construction and curing measures adopted in element prefabrication are the key factors for controlling early temperature cracking of an immersed tunnel, and using the construction of the Shengjiamen immersed tunnel in Zhoushan as an example, this paper analyzes the influences of integral casting, layered casting, curtain curing and water storage curing on the temperature field and stress field of elements during prefabrication based on MIDAS FEA software. The obtained results are compared with the measured ones, showing that: 1) the maximum hydration temperature occurs at the tunnel floor during element prefabrication, with its peak value occurring within 1 or 2 days after casting; 2) the maximum temperature stress occurs at the haunch of the interface between the floor and sidewall, with the value being close to or even greater than the current age tensile strength, which easily causes cracking; 3) layered casting can accelerate heat loss inside the element and curtain curing can reduce the differences of temperature inside and outside of the element, all of which can be used to effectively reduce early temperature stress and cracking risk to the element; 4) water storage curing may cause great temperature differences and is not suitable for the early stage of construction.
Abstract：
Considering that construction and curing measures adopted in element prefabrication are the key factors for controlling early temperature cracking of an immersed tunnel, and using the construction of the Shengjiamen immersed tunnel in Zhoushan as an example, this paper analyzes the influences of integral casting, layered casting, curtain curing and water storage curing on the temperature field and stress field of elements during prefabrication based on MIDAS FEA software. The obtained results are compared with the measured ones, showing that: 1) the maximum hydration temperature occurs at the tunnel floor during element prefabrication, with its peak value occurring within 1 or 2 days after casting; 2) the maximum temperature stress occurs at the haunch of the interface between the floor and sidewall, with the value being close to or even greater than the current age tensile strength, which easily causes cracking; 3) layered casting can accelerate heat loss inside the element and curtain curing can reduce the differences of temperature inside and outside of the element, all of which can be used to effectively reduce early temperature stress and cracking risk to the element; 4) water storage curing may cause great temperature differences and is not suitable for the early stage of construction.
.Simulation Analysis of the Influences of Construction and Curing Measures on the Early Temperature and Stress of an Immersed Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2016,V53(2): 128-133
2016, Vol. 53 