In Situ Stress Measurements in the Lhasa Terrane, Tibetan Plateau, China

来源 :Acta Geologica Sinica(English Edition) | 被引量 : 0次 | 上传用户:wangcn426
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
Tectonic activities are frequent in the Lhasa terrane because of the ongoing collision between the India and Eurasia plates. Knowledge of the stress state is critical to evaluate the crustal stability and the design of underground excavations. Because of the limitations imposed by natural conditions,little research has been performed on the present crustal in situ stress in the Tibetan Plateau,and further study is imperative. In this study,hydraulic fracturing measurements were conducted in Nyching County(LZX) and Lang County(LX),Lhasa terrane to characterize the shallow crustal stress state. The results indicate that the stress state in the LZX borehole is markedly different from that in the LX borehole,in both magnitude and orientation. At the same measurement depths,the magnitudes of horizontal principal stresses in the LX borehole are 1.5–3.0 times larger than those in the LZX borehole. The stress regime in the LX borehole favors reverse faulting characterized by SH>Sh>Sv,where SH,Sh,and Sv are maximum horizontal,minimum horizontal,and vertical principal stresses,respectively. The SH and Sh values are approximately three and two times greater than Sv. Fracture impression results reveal that SH in the LX borehole are predominantly N–S,while in the LZX borehole the maximum horizontal principal stress is mainly in the NNE-direction. The heterogeneity of the regional stress state might be a result of the population and distribution of local structures and seismic activities. The stress state in the LX borehole has exceeded the critical state of failure equilibrium,and there is an optimally orientated pre-existing fault near the borehole. It can be concluded that the optimally orientated fault is likely to be active when the stress has built up sufficiently to destroy the frictional equilibrium; it is suggested that research focus should be placed on this in future. The stress states in boreholes LZX and LX indicate uniformity of the regional stress field and diversity of the local stress fields resulting from the interactions among regional dynamic forces,tectonic stress field,and geological structures. Tectonic activities are frequent in the Lhasa terrane because of the ongoing collision between the India and Eurasia plates. Knowledge of the stress state is critical to evaluate the crustal stability and the design of underground excavations. Because of the limitations imposed by natural conditions, little research has been performed on the present crustal in situ stress in the Tibetan Plateau, and further study is imperative. In this study, hydraulic fracturing measurements were conducted in Nyching County (LZX) and Lang County (LX), Lhasa terrane to characterize the shallow crustal stress state. The results indicate that the stress state in the LZ bore bore is markedly different from that from the in LX borehole, in both magnitude and orientation. At the same measurement depths, the magnitudes of the principal principal stresses in the LX bore holes are 1.5-3.0 times larger than those in the LZX borehole. The stress regime in the LX borehole favors reverse faulting characterized by SH> Sh> Sv, where S H, Sh, and Sv are maximum horizontal, minimum horizontal, and vertical punctuations, respectively. The SH and Sh values ​​are approximately three and two times greater than Sv. Fracture impression results reveal that SH in the LX borehole are predominantly N-S , while in the LZX borehole the maximum horizontal principal stress is mainly in the NNE-direction. The heterogeneity of the regional stress state might be a result of the population and distribution of local structures and seismic activities. The stress state in the LX borehole has exceeded the critical state of failure equilibrium, and there is an optimally orientated pre-existing fault near the borehole. it can be concluded that the optimally orientated fault is likely to be active when the stress has built up adequ to destroy the frictional equilibrium; it is suggested that research focus should be placed on this in future. The stress states in boreholes LZX and LX indicate uniformity of the regional stress field and div ersity of the local stress fields resulting from the interactions among regional dynamic forces, tectonic stress fields, and geological structures.
其他文献
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
世界上有延续了数千万年的原始森林,这并不奇怪,但能够屹立几千年的长寿树则令人叹为观止。这些千年古树在地球气候大起大落的变化中幸存了下来,它们见证了人类文明的兴衰,甚至在人类工业发展的浓烟毒雾中坚持到了今天。以下是如今世界上还活着的最长寿的十大树木。  1 美国加州4841岁的狐尾松“玛士撒拉”  这棵古老的狐尾松已经活了4841年,是地球上最古老的非克隆植物(不具有克隆性的植物为非克隆植物)。它生
如何让小学数学小组合作学习不流于形式,而是更有效呢?首先应建立合理的教师指导小组;其次、熟练掌握合作技能;再其次、正确把握合作契机;第四、充分发挥教师作用,使小组合作可以实
高中阶段的学生已经积累了一定的生活经验,同时已形成初步的人生观和价值观,政治教师可以利用这一优势,将生活化教学融入到政治课堂教学之中.本文介绍了生活化教学的重大意义
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
期刊
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7
The subsidence history of the Soutpansberg Basin was reconstructed by a tectonic subsidence analysis coupled with backstripping calculations based on data of ne
开栏语:过去的两年,本刊在曾以大篇幅连载著名发明家张开逊教授的文章《回望人类发明之路》。我们看到,古代的中国曾经有过非常璀璨的文明。但是,“尽管中国古代对人类科技发展做出了很多重要贡献,但为什么科学和工业革命没有在近代的中国发生?”这是著名的“李约瑟难题”。  诺贝尔科学奖是全球的科技界最高奖项。从1901年设立至今已经有113年的历史。迄今为止,已经有8位华裔科学家获得诺贝尔奖,但是,还没有一位
Three identical model boxes were made from transparent plexiglass and angle iron. Using the method of sinking water and according to the sedimentary rhythm of s
为探究吕家坨井田地质构造格局,根据钻孔勘探资料,采用分形理论和趋势面分析方法,研究了井田7