2. The maximal principal compressive stress nearby Beijing and Tianjin is towards NE60~70, while that around Tangshan and its eastern side is close to the EW direction.
The paper made use of the earthquake records before and afper 2 Datong-Yanggao earthquakes and ana-lyzed the change of its focal stress field,the result showed that two prhcipal stress axis orientations of the fo-cal stress field before M6.1 earthquake had reversed,the reversed time of the principal compressive stress ax-is was for 10 months,and the extensional stress for 2 months.
most of the strong earthquakes occurred in the most dangerous ranges with angles of 30°-60° between the principal compressive stress and fault surface;
It is different from the result of Jiashi large earthquake swarms in 1997-1998, its main compressive stress field is NNE - SSW direction, seismic rupture is NNE direction.
There are two preferred polarization directions from the fast shear wave,N32°E and N94°E respectively. Both deviate much from the direction of the principal compression stress axis,N140°E,of the source stress field. They were not resulted from the anisotropy of the stress-induced cracks(EDA).
The faults and seismicity in Bohai and its adjacent regions are controlled by the NEE regional compression stress produced by plate movement and tectonic stress produced by uplift of upper mantle in Bohai.
The apparent resistivity data of 11 stations observed in or near the epicentral regions of 6 strong earthquakes are processed by the normalized monthly rate method. The results show that in the medium short and short imminent terms of earthquake preparation the variation rate perpendicular (or near perpendicular) to the direction of maximum principal compression stress is greater than that parallel (or near parallel) to the direction.
The result shows that the present tectonic stress field results from 140°～320°trending tensile stress in addition to 55°～235°_trending pressure stress which is twice as large as the former.
反演结果表明，华北地区现今构造应力场除受55°～235°方向的压应力外，同时还受到140°～320°方向的拉应力，其中 N E－ S W 向的压应力最大，约为 S E－ N W 向的2 倍。
And the NE polarization direction is closed to N70° E which is the principal pressure stress direction in this focal stress field. So,it is deduced that the S-wave fission of Xiuyan Ms5.4 earthquake in 1999 is the result of medium anisotropy caused by the focal stress field.
The studies in this paper have. showed that before and after several moderately strong shocks in Ningxia, the strikes of P (main pressure stress) axes have changed distinctly, deviating from the strikes of P axes in normal structural stress field or drawing no conclusions.
Combined the results for these two events with the mechanisms of others in this area, it was shown that the source stress field is characterized by a pressure stress of NNE or NE, and a tension stress of NWW or NW.
The seismic area of the M 7.0 Lijiang earthquaeke is located in the present tectonic stress field region with complex space distribution in southwestern China and lies in specific tectonic environment acted probably by multiple tectonic dynamic sources with the SSE dominant direction of principal pressure stress in regional stress field.
The analysis shows that the principal compressional stress axes P are mostly in the northeast east direction and the extensional axes T in the north northwest direction, both P and T dip angles less than 30° are nearly horizontal.
The result indicates that the principal compressional stress axes are NE～NEE direction and the principal extensional stress axes are NW～NNW in direction in every station area.
According to the Guangdong Digital Seismic Network records, the focal mechanism is obtained from the earthquake (M_S4.9) in Yangjiang on September 17, 2004. The strike is 57, the dip angle is 47 and the rake is 69 of the nodal plane, the azimuth and the dip angle of principal compressional stress axes P is 342 and 0, respectively; the azimuth and the dip angle of principal extensional stress axes T is 252 and 75, respectively, the type is reverse faulting.
The NE-SW compressive stress from the Qinling orogenic belt and detachment layers in the covering strata are the two most important determinants of deformation style.
Their Raman spectra indicate good phase purity and a compressive stress as high as about 4 GPa due to the thermal-expansion mismatch between the diamond and the ceramic.
Algorithms for estimating elastic stress in ferromagnetic steel structures are based on measurements of the residual magnetization Mr as a function of tensile and compressive stress σ0 after quenching and tempering at different temperatures Ttem.
Experimental and theoretical data on the magnetoelastic increments of magnetization induced under tensile and compressive stress are used to find the magnetization distributions.
The compressive stress-strain diagrams are obtained for layered single crystals of the LiF-LiF:Mg type with different orientations of the reinforcing layers at T = 4.2 and 300 K.
By using this model, the ceramics piezoelectric coefficient d33, its dependence on the longitudinal compression stress σ, and the relative numbers of 90° and 180° domain switches induced by the action of the stress σ were determined.
Failure forms caused by axial ultimate compression stress in three softwood and nine hardwood species and in model specimens made of wood, paper and plastics are described.
Forty-five women with low urethral pressure stress incontinence were retrospectively reviewed: 21 underwent colposuspension and 24 a pubovaginal sling.
The interaction problem among fractures under the action of compressional stress is studied in this paper by using the finite element method and boundary element method respectively.
The direction of maximum principal compressional stress rotated clockwise with respect to the previous tectonic stress field, the stress field was mainly of strike-slip type.
From the west of Zhenyuan-Yingpanshan fault to the south of Longling fault zone, the maximum compressional stress is in NNE direction and the stress regime is mainly of strike-slip type.
In Longling fault zone and the area north to it, the direction of maximum compressional stress is near-NS or NNW, the stress regime is of strike-slip type.
Based on focal mechanism solutions done before in Liaoning region, and by using of the P wave onset data, the fault plane solutions of 13 stronger carthquakes in this region are obtained. After that the stress field characteristic are studied. The result of 23 earthquakes (3.5) statistics shows that the principal compressional stress axles P is concentrated in the NEE direction while the tensile axies T in the NNE direction; the null axies N are mostly rather steep; the fault activities appear to be of stri...
In this paper,we discuss the characteristics and application of rock triaxial strength test with the laboratorial examples.The experimental results are shown as follows.①The rock triaxial compression and shearing strengths are shown increment with the confining pressure(depth).Under the low confining pressure,the strengths increase linearly.But when the confining pressure is over the limit,the strengths increase nonlinearly with the accretion rate gradually going down.Under the higher confining pressure,the...
压应力
compressive stress 
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