The temperature and pressure at the focus is different from the shallow of the crust and the ground. The higher temperature and pressures, the larger conjugate rupture angle.

The temperature and pressure at the focus are different from that of the shallow part of crust and the ground. The higher temperature and pressure,the larger conjugate rupture angles.

It quite systematically expounds the concepts of infinitesimal and finite decimal, continuity and uniformity involved in the deformatiom geometry analysing the oil geological structures, discusses Coulomb-Mohr theoretical expression, and analyses the variable range of shear angle (θ) in deformation ellipsoid. Therefore, the theoretical basis is presented to demonstrate the high angle underthrust.

(2) strong preferred orientation, augen structure, and small shear angle developed within the fault materials are the indications of creep slip along the eastern segment of Altun fault zone;

When t→∞, the static-state distortion strain energy criteria and the formula for determiming static-state fracture angle are obtained.

In addition, the relative accuracy of three current fracture theories and the new criterion in predicting static-state mixed-mode initiation fracture loading and fracture angle in rock have been evaluated experimentally.

Perimortem injuries may be distinguished from postmortem damage by examining certain attributes such as fracture angle and fracture margins.

Numerical results for the fracture angle are obtained to illustrate the application of the proposed formulation.

The results showed a reduction in the mean fracture angle from 17° preoperatively to 1° postoperatively.

In this paper, by use of focal mechanism solutions of 31 small shocks and 15 single stations(average result), the characteristics of stress fields of Yihe—Shuhe fault belt and its adjacent region are studied. The results have shown that the directions of principal stress axes, P and T, in Yihe-Shuhe fault belt are 72° and 342°, respectively, which agree with that in Jiangsud Shandong-Anhui-Henan region; the stress field difference at vertical variant segments in the fault belt is obvious. The statistical result...

In this paper, by use of focal mechanism solutions of 31 small shocks and 15 single stations(average result), the characteristics of stress fields of Yihe—Shuhe fault belt and its adjacent region are studied. The results have shown that the directions of principal stress axes, P and T, in Yihe-Shuhe fault belt are 72° and 342°, respectively, which agree with that in Jiangsud Shandong-Anhui-Henan region; the stress field difference at vertical variant segments in the fault belt is obvious. The statistical result of mechanism of earthquakes at different depth has shown that the focal mechanism of earth quakes in depth more than 17km appers to reflect crustal stress field more really. The mechanical model of Yihe-Shuhe fault belt is given. Finally, the recent characters of seismicity in this fault belt and its relation to active fault, stress state and fracture angle have been discussed.

Based on the geological characteristics of Tianfu anticlinal structure, this article puts forward the problem of deformation geometry of high angle underthrust. It quite systematically expounds the concepts of infinitesimal and finite decimal, continuity and uniformity involved in the deformatiom geometry analysing the oil geological structures, discusses Coulomb-Mohr theoretical expression, and analyses the variable range of shear angle (θ) in deformation ellipsoid. Therefore, the theoretical basis is presented...

Based on the geological characteristics of Tianfu anticlinal structure, this article puts forward the problem of deformation geometry of high angle underthrust. It quite systematically expounds the concepts of infinitesimal and finite decimal, continuity and uniformity involved in the deformatiom geometry analysing the oil geological structures, discusses Coulomb-Mohr theoretical expression, and analyses the variable range of shear angle (θ) in deformation ellipsoid. Therefore, the theoretical basis is presented to demonstrate the high angle underthrust.

A series triaxial compressional tests of a reservoir sandstone(J_2s)were made at different temperatureand pressure.The stress—induced cracks generated in the tested samples were studied both macroscopicallyand microscopically,and some geometrical parameters of those cracks such as the lenth,the direction andthe density were measured carefully.The observed data show that there is an instinct relation between thegeometrical characteristics of the cracks and the TP conditions under which the specimens were tested.When...

A series triaxial compressional tests of a reservoir sandstone(J_2s)were made at different temperatureand pressure.The stress—induced cracks generated in the tested samples were studied both macroscopicallyand microscopically,and some geometrical parameters of those cracks such as the lenth,the direction andthe density were measured carefully.The observed data show that there is an instinct relation between thegeometrical characteristics of the cracks and the TP conditions under which the specimens were tested.When the applied stress is lower then 50% of the compressional strength of the rock,almost all of thecracks in the samples are intragranular or intergranular microcracks with the same or smaller size of thegrain and the absolute number of the cracks is also small.the across—granular cracks occure only when theapplied stress is increased to 80% of the compressional strength,and the angles between the crack planeand (?) in thin sections gradually approach to the final macroscopical fracture angle when the cracks aregetting larger and larger.Antisteps were found on each of the macrocrack surfaces of the samples tested at the TP conditionsnot less than 65℃,75MPa.Based on the observed results,a mechanism is proposed for the transition from microcracks(?)roliferation to the formation of the mainfracture.