共查询到20条相似文献，搜索用时 73 毫秒
1.
本文我们利用钻孔岩样的力学性质,详细观察应力引起的钻孔崩落和由水压致裂实验估计的最小水平主应力值S_(kmin),构成了卡洪山口(Cajon Pass)钻孔直至3.5km深的最大水平主应力。S_(Hmax)的垂直剖面。正如基本上与所有其它的钻孔一样,卡洪山口钻孔的水压致裂应力测量得到的,最小水平主应力S_(hmin)数据比最大水平主应力S_(Hmax)的数据多得多(并且更加可靠)。为利用观察的井壁崩落约束S_(Hmax)的值,使用了由有效应变能准则得出的脆性破裂准则。这个破裂准则也允许我们考虑钻孔周围的三向应力,并考虑孔隙流体压力以不同方式对岩石强度的影响。比较从崩落估计出的S_(Hmax)剖面和从水压致裂实验得出的S_(Hmax)的估计值表明:当孔隙压力对水压致裂破裂起始的影响可以忽略时,它们相当符合。在这个钻孔中,直至3.5km深的总体应力状态相当于倾滑兼走滑断层型应力状态。最大水平主应力剖面有几个应力值显著减小的地方,它们与主要的断层带有关,这个结果和由水压致裂得出的最小水平主应力S_(kmin)剖面一致。 相似文献
2.
基于水压致裂数据估计岩体的最大应力主要取决于对破裂的确定和二次破裂压力.这种估计的误差可归结于注入系统压缩性,耦合粘性流体在水压裂隙中的流动和裂隙通过井孔周围变化的应力场的增长.这些机制的作用还没有很好的定量化.本文中的两个数值模型为评估非理想条件下与破裂压力分析有关的误差提供了一个基本工具.这两个数值模型是注入系统的... 相似文献
3.
4.
本文以笔者所了解的情况,介绍了联邦德国等国利用水压致裂和钻孔崩落研究地应力的近况。水压致裂应力测量目前值得注意的动态是:①世界上拥有小型轻便的软管水压致裂设备的研究小组愈来愈多;②联邦德国鲁尔大学地球物理研究所计划研制可用于更深的钻孔(6公里),并将井下超声电视、测震计与水压致裂封隔器装在一起的新设备;③利用一孔多段以至地点相近的多个钻孔的水压致裂数据,只用封闭压力和张开裂缝方位的观测值反推地应力大小和方向的参数;④破裂力学理论的初步应用。此外,在用钻孔崩落研究地应力方面的主要成就是,对有孔岩石标本所作的单轴压缩试验以及理论分析表明,崩落机制主要由岩壁张破裂(而不是剪切破裂)引起。 相似文献
5.
水库蓄水为什么会诱发地震,至今人们的认识不尽一致,原因是多方面而且是十分复杂。但无论哪种诱发机制理论,水的作用都被列为重要因素。从岩石力学观点看,水的作用不仅使岩体(或断裂带)的性质发生“软化”,而且随着孔隙压力的增加使基岩的应力状态发生变化,从而改变了岩石的强度和变形特性。作者1981年发表的论文中对“软化”问题已作了论述,本文主要探讨孔隙压力的影响。试验采用新丰江水库主要断裂带区的花岗岩30块试件,分成烘干和饱和两组,在不同围压和轴压力作用下,通过中间孔注液产生孔隙压力,使岩样破裂,简称为“水压致裂三轴试验法”。这种试验测量其致裂强度特性,变形特性及破裂模式等一系列参数,为水库地震诱发机制的研究提供一个方面的判据。 相似文献
6.
岩石水压致裂和诱发地震的实验研究 总被引：5，自引：0，他引：5
用7种岩石各制备了几类不同预裂纹的系列试件，并在不同围压下进行水压致裂强度实验。结合典型的水库诱发地震的实际资料和现今构造应力场的实验结果，以及应用岩石强度理论和岩石断裂力学的一些原理、方法，进行岩石孔隙水压诱发地震的探讨。初步结果为：(1)若岩体内构造应力很小，一定大小的孔隙水压力σp，可直接使岩体内的薄弱面致裂并发生小地震。(2)若构造应力较大，存在两类诱发地震的可能：①对岩体浅部一些走向与构造应力的主压应力σ1方向相近的薄弱面，σp可促使其发生张性破裂并诱发小地震。②当构造应力接近于断裂的抗剪强度时，因σp，降低了断裂面上的正应力σn，使原处于稳定状态的断裂失稳，发生滑移破裂并诱发出地震。σp导致断裂的破裂深度增大，使诱发地震的震级大于原潜在的地震震级。(3)各种岩体均存在着一个极限深度，此深度后不再有诱发地震。 相似文献
7.
8.
9.
为了研究三峡拟建水库蓄水诱发地震的可能性,1988年在三峡拟建坝址三斗坪附近的茅坪镇花岗岩体中进行了水压致裂应力测量.钻孔深度800m,在154—791m 深度中的16个深度段进行了水压致裂 相似文献
10.
11.
In this paper, the changes in sediment transport over 51 years from 1955 to 2006 in the Kuye River in the Loess Plateau in China are assessed. Key factors affecting sediment yield and sediment transport, such as precipitation depth, discharge, and human activities are studied. To investigate the changes in sediment yield in this watershed, a trend analysis on sediment concentration, precipitation depth, and discharge is conducted. Precipitation depths at 2 Climate Stations （CSs）, as well as discharge and sediment transport at 3 Gauging Stations （GSs） are used to assess the features of sediment transport in the Kuye River. The rtmoff modulus （defined as the annual average discharge per unit area, L/（s·km^2）） and the sediment transport modulus （defined as the annual suspended sediment transport per unit area, t/（yr km^2）） are introduced in this study to assess the changes in runoff and sediment yield for this watershed. The results show that the highest average monthly discharge during the study period in the Kuye River is 66.23 m^3/s in August with an average monthly sediment concentration of 88.9 kg/m^3. However, the highest average monthly sediment concentration during the study period in the Kuye River is 125.34 kg/m^3 and occurs in July, which has an average discharge of 42.6 m^3/s that is much less than the average monthly discharge in August. It is found that both the runoff modulus and sediment transport modulus at Wenjiachuan GS on the Kuye River has a clear downward trend. During the summer season from July to August, the sediment transport modulus at Wenjiachuan GS is much higher than those at Toudaoguai and Longmen GSs on the Yellow River. The easily erodible loess in the Kuye River watershed and the sparse vegetation are responsible for the extremely high sediment yield from the Kuye River watershed. The analyses of the grain size distribution of suspended load in the Kuye River are presented. The average monthly median grain size of suspended load in the Kuye River is largest in February and then decreases until June. In July, the average monthly median grain size of suspended load approaches another peak and decreases until September. Then, the median grain size of suspended load starts to increase until February of the following year. However, the average monthly median grain size of suspended load in the Yellow River at Toudaoguai and Longmen GSs is the smallest between early summer and late fall The median grain size in the Yellow River starts to increase in November and approaches the largest size in January. 相似文献
12.
3He/4He ratios up to 3.5 times the ratio of atmospheric He were found in groundwater samples. The3He enrichment can be attributed to radiogenic3He produced by in-situ beta-decay of3H. This shows that tritiogenic3He is accumulating in confined waters. From tritiogenic3He and3H concentrations, ages of groundwaters can be calculated. Detection of tritiogenic3He gives a tool to trace a tritium contamination which occurred in the past and cannot be assessed only by the3H counting method. 相似文献
13.
14.
Observations of trace gases (SO2, NH3, NO2 and O3) were made during the period 1981 to 1984 at 6 different locations representative of urban industrial, urban, nonurban, thermal power plant and marine environment. Diurnal variations of the trace gases were studied in an urban environment. Except in the urban industrial environment, the concentration of NH3 was found in the range of background values. Also, the average concentrations of NO2 and O3 at the different environments were in the order of background values. However, the concentrations of SO2 were substantially higher by about 7 times, in urban industrial and thermal power plant environments. The diurnal variations of SO2, NH3 and NO2 showed anitphase relationship with surface temperature at the urban environment station which is relatively free of industrial pollution. Discussion is centred on trace gas variations in different environments in India together with the values reported for various countries in the world. 相似文献
15.
The aim of this study is to estimate likely changes in flood indices under a future climate and to assess the uncertainty in these estimates for selected catchments in Poland. Precipitation and temperature time series from climate simulations from the EURO-CORDEX initiative for the periods 1971–2000, 2021–2050 and 2071–2100 following the RCP4.5 and RCP8.5 emission scenarios have been used to produce hydrological simulations based on the HBV hydrological model. As the climate model outputs for Poland are highly biased, post processing in the form of bias correction was first performed so that the climate time series could be applied in hydrological simulations at a catchment-scale. The results indicate that bias correction significantly improves flow simulations and estimated flood indices based on comparisons with simulations from observed climate data for the control period. The estimated changes in the mean annual flood and in flood quantiles under a future climate indicate a large spread in the estimates both within and between the catchments. An ANOVA analysis was used to assess the relative contributions of the 2 emission scenarios, the 7 climate models and the 4 bias correction methods to the total spread in the projected changes in extreme river flow indices for each catchment. The analysis indicates that the differences between climate models generally make the largest contribution to the spread in the ensemble of the three factors considered. The results for bias corrected data show small differences between the four bias correction methods considered, and, in contrast with the results for uncorrected simulations, project increases in flood indices for most catchments under a future climate. 相似文献
16.
Cu concentrations in surface (river and lake) and subsurface waters are determined. The geographic pattern of Cu distribution in natural water is identified. This pattern is controlled by the difference between its concentrations in drained rocks and soils and the geochemical redox conditions of its migration. Territories with low, medium, and elevated Cu concentrations in natural waters are identified. The concentrations of Cu in natural waters of the region are found to be generally lower than the Clarke values. 相似文献
17.
Changes in thermal extremes of the climate of Poland in 1951–2010 are examined. Warm extremes have become more frequent, while cold extremes have become less frequent. In the warming climate of Poland, the increase in the number of extremely warm days in a year and the decrease in the number of extremely cold days in a year have been observed. Also the increase of the maximum number of consecutive hot days in a year and the decrease of the maximum number of consecutive very cold and extremely cold days in a year have been observed. However, the trends are not of ubiquitous statistic significance, as the natural variability is strong. 相似文献
18.
M. MONIRUL QADER MIRZA 《水文科学杂志》2013,58(5):613-631
Abstract The basin area of the Ganges River in Bangladesh is extremely dependent on a regular water supply from upstream to meet requirements for agriculture, fisheries, navigation, salinity control, and domestic and industrial sectors. In 1975, India commissioned a barrage on the Ganges River at Farakka to divert a significant portion of the dry season flow in order to make the Calcutta Port navigable. Statistical analyses of discharge and water level data have been carried out to determine if significant changes have occurred in the hydrology of the Ganges system in Bangladesh in the post-Farakka period. Siltation of the Gorai River (an offtake of the Ganges River) has also been examined using the stage-discharge relationship and regression analysis. The analyses show that the diversion has caused considerable hydrological changes in the Ganges system in Bangladesh. The water supply in the dry season has been reduced substantially, while siltation of the Gorai River has increased significantly. 相似文献
19.
20.