On Frost-Heave Calculation Model Based on a Broken Freeze-Thaw Circle and Its Influential Factors
(1 School of Highway, Chang′an University, Xi′an 710064; 2 Shanxi Provincial Major Laboratory for Highway Bridge & Tunnel,Chang′an University, Xi′an 710064; 3 China Gezhouba Dam Group Investment Holding Co. Ltd., Wuhan 430000)
Abstract:
The force created by frost heaves is one of the major influential factors for tunnels in cold regions, and it is very important to study this frost-heave force. Several kinds of calculation models and mechanisms for this frost-heave force are analyzed and summarized, and a model of frost heaving in a broken freeze-thaw circle is established based on a frost-heaving model for a weathered layer. A frost-heave force calculation formula is deduced according to displacement continuity conditions, the relation of frost-heave force and influential factors are analyzed by the control variable method, and the influence of different factors on the frost-heave force are analyzed by the partial correlation method. The results show that: 1) the frost-heave force value is related to the frozen depth, the frostheave ratio of the freeze-thaw circle, the lining and the resistance coefficient of the original rock mass; 2) the frostheave ratio of the freeze-thaw circle has a close relationship to the degree of breakage, moisture content and water supply conditions; 3) the orders of effects of various factors on the frost-heave force are: the frozen depth > the frostheave ratio of the freeze- thaw circle > the elastic equivalent resistance coefficient of lining. A case calculation shows that the frost-heave force scope is 7.43~11.05 MPa when the frozen depth is 2~3 m, and the calculated frostheave force is larger than that of the measured values. Countermeasures to mitigate the frost-heave force are discussed based on influential factors.
.On Frost-Heave Calculation Model Based on a Broken Freeze-Thaw Circle and Its Influential Factors[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(6): 93-102