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1.
We present the results of tectonophysical reconstruction of natural stresses of the Earth's crust in the Altai–Sayan mountain region using cataclastic analysis of fault slips and seismic data on the focal mechanisms of earthquakes. This method allows one to obtain the parameters of the total stress tensor by invoking additional data: generalized experimental data on the brittle fracture of rocks, seismic data on the released stress of strong earthquakes, and data on the topography and density of rocks. Results of the tectonophysical reconstruction of stresses showed significant inhomogeneity of the stress state, which is manifested not only in the variation of the strike and dip of the principal axes of the stress tensor, determining changes in the geodynamic regime of the Earth's crust, but also in the close location of the regions of high and low isotropic tectonic pressure in relation to the lithostatic pressure. The variance of the ratio of tectonic pressure to lithostatic pressure is in the range of 0.59–1.31, with an average value for the region close to unity. This paper discusses internal or external mechanisms capable of generating the stress field obtained by the tectonophysical reconstruction. 相似文献
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<正>supported by the Science and Technology Project of China(grant no.WFSD-00003),focuses on the in-situ stress measurements in the WFSD-1 borehole Stress is defined as the natural stress existing between 相似文献
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The Stress–Strain State of Recent Structures in the Northeastern Sector of the Russian Arctic Region
Doklady Earth Sciences - Complex research to determine the stress–strain state of the Earth’s crust and the types of seismotectonic destruction for the northeastern sector of the... 相似文献
5.
《《地质学报》英文版》1989,63(3)
The Cretaceous-early Eocene tectonic stress field in China was reconstructed using the data of 369 largeand medium-scale flexural folds and 157 joint sets. It was found that the maximum compressive principal stress axis in eastern China dips 32° NE (nearly horizontal), and strikes SW 212°, whereas that in western China dips 15° NE (also nearly horizontal) and trends SW 195°. The estimation of the dip angles of fold limbs and the palaeotectonic stress values indicates that there was a tendency of gradual weakening of tectonism from southwestern to northeastern China in the Cretaceous-early Eocene. At the depth of 2-3 km, the differential stress value changes from 183 MPa in Tibet to 100 MPa in North and East China.The authors consider that the tectonic stress of this period was related to the north-northeastward movement and push of the Indian-Australian plate. 相似文献
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Geotechnical and Geological Engineering - In order to present an elastic solution for twin circular tunnels’ stress distribution in hydrostatic stress field, based on the complex variable... 相似文献
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Tensile Fractures and in situ Stress Measurement Data Constraints on Cretaceous–Present Tectonic Stress Field Evolution of the Tanlu Fault Zone in Shandong Province, North China Craton 
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下载免费PDF全文 Tectonic stress fields are the key drivers of tectonic events and the evolution of regional structures. The tectonic stress field evolution of the Tanlu fault zone in Shandong Province, located in the east of the North China Craton (NCC), may have preserved records of the NCC’s tectonic history. Borehole television survey and hydraulic fracturing were conducted to analyze the paleo and present tectonic stress fields. Three groups of tensile fractures were identified via borehole television, their azimuths being NNW–SSE, NW–SE and NE–SW, representing multiple stages of tectonic events. Hydraulic fracturing data indicates that the study region is experiencing NEE–SWW-oriented compression and nearly-N–S-oriented extension, in accordance with strike-slip and compression. Since the Cretaceous, the orientation of the extensional stress has evolved counterclockwise and sequentially from nearly-NW–SE-oriented to NE–SW-oriented and even nearly N–S-oriented, the stress state having transitioned from strike-slip-extension to strike-slip-compression, in association with the rotating and oblique subduction of the Pacific Plate beneath the NCC, with the participation of the Indian Plate. 相似文献
8.
WU Weiwei LONG Feng LIANG Mingjian WEI Yaling SUN Wei CHEN Xuefen ZHAO Jing 《《地质学报》英文版》2020,94(5):1635-1650
As a case study of spatial and temporal variations in earthquake stress drops between the 2008 Ms 8.0 Wenchuan and 2013 Ms 7.0 Lushan earthquakes, we computed 1828 stress-drop values for earthquakes with magnitudes 1.7 ≤ ML ≤ 5.0 during an eight-year time span before and after major earthquakes. We divide the study area into three subregions (the southern segment of the Longmen Shan fault zone; the southwestern junction of the Longmen Shan and Sichuan Basin; and the southwestern margin of the Sichuan Basin) and calculate individual event stress drops in each. The results show that regions of alternating high and low stress drop are found on either side of the southwestern segment of the Longmen Shan fault zone. During the two-year period after the 2008 Ms 8.0 Wenchuan earthquake, the stress state of the southern Longmen Shan fault shows no significant change. A marked increase in stress level appears about 18 months before the 2013 Ms 7.0 Lushan earthquake near the Lushan hypocenter zone. Two months after the Ms 7.0 event, the stress drops suddenly attenuate, with significantly less seismic energy release per event. We find that changes in the patterns of high and low stress drop values are consistent with the process of stress accumulation or transfer from the pre-mainshock to post-mainshock periods. The results indicate that major earthquakes are the dominant cause of temporal and spatial evolution in stress levels. Stress drop variations show obvious temporal and spatial patterns that may suggests subtle changes in the character of stress fields on faults and spatial variations related to local intense compression and tectonic effects. 相似文献
9.
The formation and distribution of fractures are controlled by paleotectonic stress field,and their preservative status and effects on development are dominated by the modern stress field. Since Triassic,it has experienced four tectonic movements and developed four sets of tectonic fractures in the extra low-permeability sandstone reservoir at the south of western Sichuan depression. The strikes of fractures are in the S-N,NE-SW,E-W,and NW-SE directions respectively. At the end of Triassic,under the horizontal compression tectonic stress field,for which the maximum principal stress direction was NW-SE,the fractures were well developed near the S-N faults and at the end of NE-SW faults,because of their stress concentration. At the end of Cretaceous,in the horizontal compression stress fields of the NE-SW direction,the stress was obviously lower near the NE-SW faults,thus,fractures mainly developed near the S-N faults. At the end of Neogene-Early Pleistocene,under the horizontal compression tectonic stress fields of E-W direction,stress concentrated near the NE-SW faults and fractures developed at these places,especially at the end of the NE-SE faults,the cross positions of NE-SW,and S-N faults. Therefore,fractures developed mostly near S-N faults and NE-SW faults. At the cross positions of the above two sets of faults,the degree of development of the fractures was the highest. Under the modern stress field of the NW-SE direction,the NW-SE fractures were mainly the seepage ones with tensional state,the best connectivity,the widest aperture,the highest permeability,and the minimum opening pressure. 相似文献
10.
Buckling failure occurs in the open pit mines in the Quadrilátero Ferrífero of the State of Minas Gerais, Brazil. In this study, this failure mechanism is evaluated through stress–strain analysis, using the finite element software named Phase2. Many representative hypothetical models of the slopes were created in order to reproduce the conditions in open pit mines, like their geometry and foliated joints with kinematic conditions for buckling failure. Elastic and plastic simulations have been done. Strength and deformability parameters, such as discontinuity stiffness and cohesion, as well as the in situ stress field, are analyzed in order to understand their influence in the buckling failure mechanism in the global open pit mine slopes excavated in phyllites. As studies about this problem are extremely rare, the present research brings important contributions to establish the basic conditions for this kind of failure. 相似文献
11.
Yu. L. Rebetsky 《Russian Journal of Pacific Geology》2009,3(5):477-490
The field of modern tectonic stresses was reconstructed for the Earth’s crust of the northwestern segment of the Pacific subduction
zones. For this purpose, we used the method of cataclastic analysis and data on the magnitude of the stresses released at
the source of the Simushir earthquake of 2006, which allowed us to determine both the orientation of the principal stress
axes and the magnitude of the stresses and to estimate the effective strength of rock masses. The effective cohesion was estimated
for this region of the Earth’s crust as 12 bar, and the maximum shear stresses are no higher than 300 bar. The analysis of
the reconstructed stress field in the zone of the preparation of the Simushir earthquake showed that this region was almost
free of domains with high stresses where brittle failure requires considerable energy inputs. The medium level of effective
pressure indicates that this region is most favorable for the development of a large-scale brittle failure. 相似文献
12.
Characteristics of the Mesozoic and Cenozoic Tectonic Stress Fields of the Urumqi-Usu Region, Xinjiang 总被引：1，自引：0，他引：1
Tao Mingxin Lanzhou Institute of Geology Academia Sinic Beijing Jiang Minxi 《《地质学报》英文版》1993,67(1):17-31
Based on the study of folds and related conjugate shear joints, the tectonic stress fields of the Urumqi-Usu region to the north of the North Tianshan Mountains have been reconstructed. Furthermore the author discussed the tectonic movements and their dynamic features. The early tectonic movement in the investigated region occurred from the end of the Late Jurassic to the initial stage of the Early Cretaceous, with the maximum (tensile) and minimum (compressional) principal stress trajectories in the tectonic stress field being in E-W and S-N directions respectively; the late tectogenesis took place from the end of the Early Pleistocene to the initial Middle Pleistocene, with the maximum and minimum principal stress trajectories in the late stress field striking in WNW and NE-NNE directions respectively. Through computer-aided simulated calculation by the finite element method and analysis of geological structure, it has been ascertained that the early tectogenesis is a nearly N-S compressive movement and the late one a NE to nearly N-S compressive movement with reverse shear. The dynamic force which caused the tectogeneses came from the movement of the southern major fault, i.e. the North Tianshan Mountains. 相似文献
13.
A vertical profile of maximum horizontal principal stress, SHmax, orientation to 5 km depth was obtained beneath the Swiss
city of Basel from observations of wellbore failure derived from ultrasonic televiewer images obtained in two 1 km distant
near-vertical boreholes: a 2755 m exploration well (OT2) imaged from 2550 m to 2753 m across the granitic basement-sediment
interface at 2649 m; and a 5 km deep borehole (BS1) imaged entirely within the granite from 2569 m to 4992 m. Stress-related
wellbore failure in the form of breakouts or drilling-induced tension fractures (DITFs) occurs throughout the depth range
of the logs with breakouts predominant. Within the granite, DITFs are intermittently present, and breakouts more or less continuously
present over all but the uppermost 100 m where they are sparse. The mean SHmax orientations from DITFs is 151 ± 13° whereas
breakouts yield 143 ± 14°, the combined value weighted for frequency of occurrence being N144°E ± 14°. No marked depth dependence
in mean SHmax orientation averaged over several hundred meters depth intervals is evident. This mean SHmax orientation for
the granite is consistent with the results of the inversion of populations of focal mechanism solutions of earthquakes occurring
between depths of 10–15 km within regions immediately to the north and south of Basel, and with the T-axis of events occurring
within the reservoir (Deichmann and Ernst, this volume). DITFs and breakouts identified in OT2 above and below the sediment-basement
interface suggest that a change in SHmax orientation to N115°E ± 12° within the Rotliegendes sandstone occurs near its interface
with the basement. The origin of the 20–30° change is uncertain, as is its lateral extent. The logs do not extend higher than
80 m above the interface, and so the data do not define whether a further change in stress orientation occurs at the evaporites.
Near-surface measurements taken within 50 km of Basel suggest a mean orientation of N–S, albeit with large variability, as
do the orientation of hydrofractures at depths up to 850 m within and above the evaporite layers and an active salt diapir,
also within 50 km of Basel. Thus, the available evidence supports the notion that the orientation of SHmax above the evaporites
is on average more N–S oriented and thus differs from the NW–SE inferred for the basement from the BS1/OS2 wellbore failure
data and the earthquake data. Changes in stress orientation with depth can have significant practical consequences for the
development of an EGS reservoir, and serve to emphasise the importance of obtaining estimates from within the target rock
mass. 相似文献
14.
SHEN Junfeng LI Shengrong HE Shaohui ZHANG Guangshan TONG Jinggui YAN Bokun State Key Laboratory of Geological Processes Mineral Resources China University of Geosciences Beijing Key Laboratory of Lithospheric Tectonics and 《《地质学报》英文版》2006,80(5):763-769
1 Introduction Bentonite is a valuable industrial material, which is composed mainly of montmorillonite. Due to many particular characteristics such as strong water sorbility, dilatability, stickiness, high ion-exchangeable capacity, Bentonite has been used widely in many fields of application, including petroleum, metallurgy and chemical industry, textile industry, medical application, construction, mining, agriculture, environment (Koch, 2002; Wang and Wu, 2002; Wagner and Schnatmeyer, 20… 相似文献
15.
This study focuses on the stress and displacement of a circular opening that is excavated in a strain-softening rock mass incorporating the effects of hydraulic–mechanical coupling and rockbolts effectiveness. It follows the generalized Hoek–Brown failure criterion. Moreover, an improved numerical approach and stepwise procedure are proposed. This approach considers the deterioration of the strength, deformation, and dilation angle and the variation of elastic strain in the plastic region considering the effect of the hydraulic–mechanical coupling and the rockbolts effectiveness. The presented solutions were validated by FLAC results. Several examples are conducted to demonstrate the validity and accuracy of the proposed solution through MATLAB programming. Parametric studies are also conducted to highlight the influences of hydraulic–mechanical coupling and rockbolts effectiveness on stress and displacement. Results show that stress and displacement, incorporating the effects of hydraulic–mechanical coupling and rockbolts effectiveness, are between those when hydraulic–mechanical coupling or rockbolts effectiveness is considered separately. However, this theory needs more verification from practical engineering. 相似文献
16.
This article formulates the experimentally substantiated physical principle that the natural stress condition of the Earth’s crust is formed due to the superposition of stress fields, which is caused by the gravitational forces of the Earth and by tectonic and astrophysical forces that are produced by physical processes in space. The natural stress field is represented by the stress tensor regulatory components: \(\sigma _{z}^{{\text{N}}}\) = \( - \gamma H + {{\sigma }_{{zT}}} + {{\sigma }_{{z{\text{AF}}}}}\), \(\sigma _{x}^{{\text{N}}}\) = \( - \lambda \gamma H + {{\sigma }_{{xT}}} + {{\sigma }_{{x{\text{AF}}}}}\), \(\sigma _{y}^{{\text{N}}}\) = \( - \lambda \gamma H + {{\sigma }_{{yT}}} + {{\sigma }_{{y{\text{AF}}}}}\). 相似文献
17.
INTRODUCTIONThe stability of underground structures duringand after excavation is the most i mportant factor fordesigners because any kind of collapse may destroylarge parts of a finished tunnel,thereby causing ma-jor repairs and ti me loss.To avoid this problem,rock bolts are widely used as ani mportant support el-ement.These are economical,have a short installa-tion ti me,and provide reinforcement to maintain theintegrity of the stressed rock.The effect of the bearing capacity of rock b… 相似文献
18.
Yu Haizhen Zhao Wenguang Wang Ren Li Jianguo He Yang 《中国地质大学学报(英文版)》2005,16(4):340-344
INTRODUCTION Theexploitationofoffshorenaturalresourcesin thetropichaspresentedgeotechnicalengineerswith theproblemofdealingwithinsitucarbonatesedi mentsinharshconditionsforwhichfewengineering dataareavailable.Thecarbonatesedimentsaresub jectedtolargestaticstressesduetotheweightof foundationstructuresaswellascyclicstressesdueto waveaction,andinsomecases,earthquakeloading.Ithasbeenprovedthatthenatureofcyclicstresschangesoccurringintheseabeddepositduetowave loadinginvolvesacontinuousrotationo… 相似文献
19.
Numerical Method for Modeling the Constitutive Relationship of Sand under Different Stress Paths 总被引：1，自引：0，他引：1
Ren Qingyang Wang Jingtao 《中国地质大学学报(英文版)》2005,16(3):268-270
Overonehundredconstitutivemodelsforsand havebeenproposed,howeveronlyafewmodelsare widelyappliedinengineering.Therearetwochief reasonsforthis.(1)Sandiscomposedofgeological materialsandsituatedinaneutralenvironmentthat hassufferedvariousactions.Therefore,itisdifficult todescribethecomplexbehaviorofsoilsbyusinga simplemathematicalmodelwithonlyafewparame ters.(2)Therealsoexistsabasicparadoxintradi tionalmodelingmethods.Oneaspectofthemodelsis neededtodescribetheconstitutiverelationofsoilac curatel… 相似文献
20.
The results of synchronous measurements of temperature variations in a near-bottom thermocline, as well as microdeformations
of the Earth’s crust and atmospheric pressure pulsing, recorded on-shore with the help of a laser strainmeter and laser nanobarograph,
are presented. A string containing 20 thermosensors spaced at 0.5 m was used; it was placed by an anchored buoy in a place
with 21-m depth and 500 m away from the shore. A good correlation between microdeformations and atmospheric pressure variations
was observed for periods longer than 6 h. Quantitative estimates and spectral analysis via the Gilbert-Huang method for investigation
of nonstationary and nonlinear processes lead to the conclusion that, on temporal scales from tidal to several minutes, the
predominant way of formation of microdeformations in the Earth’s crust can be breaking of internal waves in a thermocline
that leads to shallow water (i.e., in the zone of “internal breakers”). 相似文献