Permafrost

64
Model of Horisontally Layered Cryolithozone
Vill S. Yakupov
(Institute of space physic and aeronomy SD RAS, Yakutsk, Russia)
Abstract: Cryolithozone boundaries, formed in rocks, saturated by fresh water, by freezing
coinside with temperature (t=0 0 C) and petrophysical ones if relating physical properties
change owing to freezing-thawing. Other boundaries in a cryolithozone are formed on
lithological and cryolithological ones in syngenetically frozen part of deposits. Degradation of
frozen strata from the beneath is followed, after levelling its temperature to t=0 0 C, by forming a
few new boundaries relating frost boundaries on, from below: 1) temperature t=0 0 C; 2)
seismic velocity, sometimes; 3) rocks constant electrical conductivity and close to it by position
dielectric permeability; 4) rocks high-frequency conductivity. They move up with different
velocities increasing in enumerated order and in time they diverge more and more- on tens and
hundreds meters. Knowing their mutual disposition it is possible to find all base parameters of a
degradation process: a time of its beginning, a thickness of its thawed part, velocities of frost
boundaries owing to different physical mechanisms of their formation.
Freezing of rocks strata, saturated by saline water, from above, is followed by freshening
porous water in the rear of the frost boundary. Cryolithozone boundaries can be determined
only by temperature measurments. Boundaries of frozen part of cryolithozone and boundaries
in it, as in p.1, responce to frozen-thawed and lithological ones. Over solt-watertight layers
taliks are forming. Their thickness depends from temperature, porosity of rocks and a quantity
of solts, brought to them by a frost boundary. During a degradation of such frozen strata from
below in the base of it new boundaries appear in a mentioned above order and of the same
origin. In solts-watertight layers they disappear and in taliks over them they start again,
simultaneously, but with different velocities.
Formation of permafrost is often accompanied by appearing under it of a fractured zone,
always water bearing, and therefore deserves to be mentioned. It is natural to suppose that
formation of these zones is a result of many times repeated processes of underlaying rocks
freezing-thawing as a responce to long-period changes of climate.
Key words: Model, horisontally Layered Cryolithozone
The research on computing method of frozen-heave force existed in
frozen ground tunnel
Wenge Qiu, Yuchao Zheng, Huijian Zhang, Dongmei Li
(school of civil engineering, southwest jiaotong university, chengdu, sichuan, China, 610031)
Abstract:The research on computing method of frozen-heave force existed in frozen ground
tunnel has been carried out by two different methods of model test and numerical analysis used
the same scale of model. The results indicate that the semi-empirical and semi-theoretical
computing method of frozen-heave force, with low temperature test determining surrounding
rock freezing circle area, original sample mechanical test defining surrounding rock physics and