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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.
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
2017, Vol. 54 