HR: 1330h
AN: T52C-0284    [PDF]
TI: Control Factor Of K$_{0}$-value, Which Indicates Initial Stress Conditions and Physical Properties Of Sediments
AU: * Suzuki, K
EM: tade-ks@arsia.geo.tsukuba.ac.jp
AF: Kiyofumi SUZUKI, Tsukuba Univ. 1-1-1 Tennodai, Tsukuba-city, 305-8571 Japan
AB: Experimental study had been done to confirm fundamental difference of physical properties between sand and mud, and to grasp influence of physical property on K $_{0}$-values. One series of compaction experiment had been done to vary their clay content and another series had been done under abnormal stress ratio. The results of experiments during compaction showed that (1) clear relationship between K $_{0}$-values and porosity and (2) rather indistinct relationship between K $_{0}$-values and clay contents. The results of abnormal stress ratio, they were no longer K0-compaction. K $_{0}$-value that is known as stress ratio under K0-condition connotes information of ductility. When sediments exhibit deviator stress, stress condition of each sediment can be expressed by a stress circle that center is placed on stress axis. On this condition, half of central angle, which is set between stress axis and tangent line of stress circle, indicate the limit angle to keep K $_{0}$-value fixing. It is known that K $_{0}$-values for sandy sediments are 0.3-0.4, though those for muddy sediments are higher than 0.7, i.e., diameter of stress circle for sandy sediments are almost twice larger than those for muddy sediments, even if they are under same compressive stress (maximum stress). It means that difference of limit angles between muddy sediments and sandy sediments could be a reason of K $_{0}$-value difference. Both of lithological effects and porosity effects on K $_{0}$-value can be explained by introducing theory of granular material for estimating contact area among grain boundaries. Equation for function of K $_{0}$-value can be described by number of grain contact, friction among grains and porosity. The function implies that magnitude of K $_{0}$-value difference between sandy sediments and muddy sediments should become smaller when they are compacted, because elements are controlled not only by lithology of each layers but also by compressive stress. Thus, when sediments undergo lateral compaction, permissible stresses are seriously different especially in case of soft sediments. Such difference may be quite important for decollement propagation.
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 3210 Modeling
DE: 5114 Permeability and porosity
DE: 8030 Microstructures
SC: Tectonophysics [T]
MN: 2003 Fall Meeting