基于Hoek-Brown的岩石横观各向同性屈服准则研究     

郑艳妮  张强  张升  贾朝军  雷明锋 《岩土力学》2022,(1):139-151

为了描述岩石强度的各向异性特征,通过引入材料的微结构张量,考虑单轴抗压强度σ_cβ随层理倾角β而变化,提出了基于微结构张量的修正Hoek-Brown屈服准则。开展不同层理倾角(0°、15°、30°、45°、60°、75°和90°)的页岩试样不同围压(0、5、10、15和20 MPa)下的三轴压缩试验,结果显示,页岩峰值强度与层理倾角β呈"U"形曲线关系,在围压较低时呈"肩"形曲线关系,弹性模量E_t和泊松比ν对围压不敏感,其平均值随层理倾角β的变化关系分别呈倒"U"形、"肩"形。页岩的微观和宏观破坏图像表明,其破坏模式受围压和层理倾角双重控制。试验值与模型预测值的对比表明,修正的Hoek-Brown屈服准则可较好地对页岩强度的各向异性进行模拟。同时,采用Koteshwar千枚岩、Koteshwar板岩、绿泥石片岩等层状结构岩石的单轴和三轴压缩试验数据,进一步验证了提出的修正Hoek-Brown屈服准则对多数具有层理结构的横观各向同性岩石峰值强度模拟具有普遍适用性,并对屈服准则在试验数据较多和较少情况下的峰值强度模拟效果进行了评价。  相似文献   

纵横波源下含油气薄储层地震响应特征的对比分析     

王雨杰  贺学铭  王志恒  屈洁  杨春 《地质论评》2023,69(Z1):429-432

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From foredeep to orogenic wedge-top: The Cretaceous Songliao retroforeland basin,China     

《地学前缘(英文版)》2023,14(3):101527

Songliao Basin, the largest Mesozoic intracontinental nonmarine basin in eastern China, initiated during the latest Jurassic as a backarc extensional basin; rifting failed and thermal cooling controlled subsidence through the early Late Cretaceous. Integrating 2-D and 3D reflection seismic and borehole data with regional geological studies, we interpret sedimentary sequence and structural patterns of the Coniacian-Maastrichtian fill of Songliao Basin as defining a retroforeland basin system developed after 88 Ma (marked by the T11 unconformity in the basin), including (1) significant increase in the thickness of the Nenjiang Formation eastward towards orogenic highlands of the Zhangguangcai Range and the convergent continental margin; (2) a shift of detrital provenance in the basin from north to southeast; and (3) propagation of E-W shortened structures, increasing eastward in amplitude, frequency, and degree of inversion toward the orogen. During latest Cretaceous, foreland basin fill progressively deformed, as the foredeep evolved to a wedge-top tectonic setting, marked by the basin-wide T04 unconformity within the upper Nenjiang Formation at 81.6 Ma. Much of the basin was brought into the orogenic wedge and eroded by the end of the Cretaceous. Late Jurassic/Early Cretaceous backarc rifting of uncratonized basement comprised of accreted terranes likely facilitated and localized the foreland. Synrift normal faults reactivated and extensively inverted as thrust faults are prominent in the eastern 1/3 of the basin, whereas folds developed above detachments in shaley early post-rift strata dominate the western 2/3 of the basin. Songliao foreland development likely was driven by changing plate dynamics and collision along the Pacific margin after 88 Ma.  相似文献   

Potential seismic landslide hazard and engineering effect in the Ya’an-Linzhi section of the Sichuan-Tibet transportation corridor,China     

《China Geology》2023,6(2):228-240

The Sichuan-Tibet transportation corridor is located at the eastern margin of the Qinghai-Tibet Plateau, where the complex topography and geological conditions, developed geo-hazards have severely restricted the planning and construction of major projects. For the long-term prevention and early control of regional seismic landslides, based on analyzing seismic landslide characteristics, the Newmark model was used to carry out the potential seismic landslide hazard assessment with a 50-year beyond probability 10%. The results show that the high seismic landslide hazard is mainly distributed along large active tectonic belts and deep-cut river canyons, and are significantly affected by the active tectonics. The low seismic landslide hazard is mainly distributed in the flat terrain such as the Quaternary basins, broad river valleys, and plateau planation planes. The major east-west linear projects mainly pass through five areas with high seismic landslide hazard: Luding-Kangding section, Yajiang-Xinlong (Yalong river) section, Batang-Baiyu (Jinsha river) section, Basu (Nujiang river) section, and Bomi-Linzhi (eastern Himalaya syntaxis) section. The seismic action of the Bomi-Linzhi section can also induce high-risk geo-hazard chains such as the high-level glacial lake breaks and glacial debris flows. The early prevention of seismic landslides should be strengthened in the areas with high seismic landslide hazard.©2023 China Geology Editorial Office.  相似文献   

复数域总体最小二乘平差   总被引：1，自引：1，他引：0  

王乐洋  于冬冬  吕开云 《测绘学报》2015,44(8):866-876

在复数域最小二乘的基础上提出了复数域总体最小二乘平差方法,推导了复数域总体最小二乘和复数混合总体最小二乘的相关公式。通过算例比较分析了复数观测值的残差的模的平方和最小(平差准则1)下及残差的实部和虚部的平方和分别最小(平差准则2)下的复数最小二乘、复数观测值和系数矩阵的残差的模的平方和最小(平差准则3)下及残差的实部和虚部的平方和分别最小(平差准则4)下的复数总体最小二乘方法的优劣。试验结果表明:平差准则1下复数最小二乘较平差准则2下得到的结果更加合理,平差准则3下复数总体最小二乘较平差准则4下得到的结果更为准确;当顾及系数矩阵误差时,平差准则3下复数总体最小二乘要优于平差准则1下复数最小二乘。  相似文献   

海底爆破振动强度衰减规律及中华白海豚保护措施研究     

费鸿禄  关福晨  包士杰  肖绍青 《海洋通报》2019,38(4):405-414

为确保海底爆破施工所诱发的振动不对中华白海豚造成危害,基于量纲分析法对萨道夫斯基经验公式进行修正,建立适用于预测海底爆破质点峰值振动速度的相似准数方程。在此基础上根据现场试验数据进行非线性回归运算,得到相关参数并分析了海底爆破振动强度衰减规律。分析表明:海底爆破质点峰值振速主要由单段装药量、监测点距爆心水平距离、覆盖层厚度及海水深度等因素决定。将参数值分别代入萨氏公式及新建公式计算预测值并进行误差估计,其平均误差分别为20.3%和10.0%,新建公式提高了对质点振速预测的准确性。利用新建公式及超压内安全振速估算保护中华白海豚的安全距离并提出相应的保护措施,为同类工程施工提供理论参考依据。  相似文献   

Characteristics of the Seismic Waves from a New Active Source Based on Methane Gaseous Detonation   总被引：1，自引：0，他引：1  

WANG Weitao  WANG Xiang  MENG Chuanmin  DONG Shi  WANG Zhigang  XIE Junju  WANG Baoshan  YANG Wei  XU Shanhui  WANG Tao 《中国地震研究》2019,33(2):354-366

Active seismic sources are critical for obtaining high resolution images of the subsurface. For active imaging in urban areas, environment friendly and green seismic sources are required. In present work, we introduce a new type of green active source based on the gaseous detonation of methane and oxygen. When fired in a closed container, the chemical reaction, i.e. gaseous detonation, will produce high pressure air over 150MPa. Seismic waves are produced when high pressure air is quickly released to impact the surroundings. The first field experiment of this active source was carried out in December, 2017 in Jingdezhen, Jiangxi Province, where a series of active sources were excited to explore their potential in mine exploration. In current work, we analyzed the seismic waves recorded by near-field accelerators and a dense short-period seismic array and compared them with those from a mobile airgun source, another kind of active source by releasing high pressure air into water. The results demonstrate that it can be used for high resolution near surface imaging. Firstly, the gaseous detonation productions are harmless CO₂ and water, making it a green explosive source. Secondly, the dominant seismic frequencies are 10-80Hz and a single shot can be recorded up to 15km, making it suitable for local structure investigations. Thirdly, it can be excited in vertical wells, similar to traditional powder explosive sources. It can also act as an additional on-land active source to airgun sources, which requires a suitable water body as intermediate media to generate repeating signals. Moreover, the short duration and high frequency signature of the source signals make it safe with no damage to nearby buildings. These make it convenient to excite in urban areas. As a new explosive source, the excitation equipment and conditions, such as gas ratio, sink depth and air-releasing directions, need further investigation to improve seismic wave generation efficiency.  相似文献   

2018年9月8日云南墨江5.9级地震预测回顾与资料论证     

杨建文  赵家本  张鹏映  何应文  王军  茶文剑 《中国地震》2019,35(3):509-520

通过分析墨江5.9级地震前预测意见和预测资料，认为云南地区M≥5.5地震平静异常突出，M≥5.0地震连续间隔时间达200天以上，通海2次5.0级地震震级偏小是震前地震活动异常的显著特征；通海地震的指示意义、前兆异常M≥5.7地震中期和M≥5.0地震短临综合预测指标是判断地震短期可能性的主要依据；1900年以来，通海50km范围内M≥5.0地震后云南地区发生M≥5.0地震优势对应关系和GNSS表征的区域面应变变化特征为地点判定提供了线索。墨江5.9级地震的预测经验及资料的论证丰富了对地震孕育复杂性的认识，为震例积累了新的资料。  相似文献   

降雨对呼和浩特地震台形变观测的影响     

杨红樱  熊峰 《地震地磁观测与研究》2019,40(5):101-108

为了研究降雨对定点形变观测的影响,在了解呼和浩特地震台形变观测环境后,分析了伸缩仪、水管倾斜仪和垂直摆倾斜仪的观测数据质量,统计了降雨量和各仪器分量的变化,并进行了相关分析,得到不同形变仪器测项数据变化幅度对降雨量的响应函数,结果显示两者间呈较好的线性相关。  相似文献   

考虑劣化屈服老化裂纹后混凝土水库堤坝排水边坡抗震性研究          下载免费PDF全文

石晶  李伟 《地震工程学报》2019,41(6):1506-1513

针对在水库堤坝排水边坡混凝土裂纹的抗震性研究中,未考虑岩土体抗剪强度参数的劣化屈服效应以及混凝土裂纹的老化,存在抗震性判断结果准确率较差等问题,提出水库堤坝排水边坡混凝土考虑老化后产生裂纹的抗震性能研究方法。模拟强震下边坡混凝土的开裂破坏过程,根据D-P屈服准则,实现对闸墩混凝土材料的屈服判断。采用薄层整体单元模拟和分离式裂纹单元,实现混凝土裂纹的数值模拟,加载地震波后,获取混凝土裂纹的强震响应规律与破坏特征。实验结果可知,本文方法对坝体位移变化的研究精度高,得到的混凝土裂纹扩展范围更为准。运用本文方法对水库堤坝排水边坡混凝土的抗震性研究准确率以及可信度较高,说明本文方法具有一定的可取性。  相似文献