小天都气垫调压室洞壁围岩原地承载力的水力劈裂测试

本文给出了该气垫调压室勘探平洞的水力劈裂测试结果。分析表明 ,随着洞深与埋深的增大 ,愈向山体内部岩体结构的完整性及其自身的承载能力愈趋增强。在 0 + 72 9m的第五测点 ,所有测段岩体抗劈裂强度的平均值为 7 4MPa。因此 ,该点具备修建气垫调压室要求的岩体力学条件 ,该点附近的洞段是布置气垫调压室较理想的位置。

测定岩体原地承载力的水力阶撑测试技术及其应用

在勘探钻孔中的各种裂隙层段上进行水力阶撑测试,能够确定岩体的原地承载力。笔者给出了某工程的应用实例,并对测试成果进行了分析。实践表明,在地质结构基本完整的情况下,岩体都具有较强的自承能力。充分利用岩体的承载能力对于科学的优化工程设计、减少投资、缩短工程建设周期,均具有重要的实际意义。

阳江抽水蓄能电站岩体水压致裂综合测试与应用研究

阳江抽水蓄能电站的输水隧洞围岩承受最大静内水压力高达7.83MPa,因此原地应力状态、围岩自身承载能力及高压透水性状等对工程的科学设计不可或缺。测量结果表明,工程区现今地壳应力场的总体特征为:水平主应力为最大主应力,最大水平主应力的优势方向为NW-NWW向;厂房和高压岔管区围岩的最大主应力值一般为14.5±0.5MPa,最小主应力值一般为9±0.5MPa;围岩自身的抗载强度一般为10~14MPa;在8~10MPa高压力作用下围岩基本不透水。洞室围岩物理力学参数的这些测试成果,为工程的科学设计提供了可靠依据。

岩石力学研究的新方向

现场岩体表征方面的研究工作是最重要的 ,从大量岩石中获得有效信息是岩石力学的有效做法。地下遥示和非破坏性评价的研究与应用 ,为从大量岩石中获得经济上可实现的信息源创造了条件 ,这应成为今后研究的一个主要目标。有关数据的不定程度 ,既与现场表征问题有关 ,又与选择的解释模型有关。因此 。

滇西一些新生代飞来峰的构造演化

在印度和欧亚大陆相互作用下,滇西三江造山带在新生代中期发生了强烈的东西向缩短,地壳物质的大规模推覆作用形成众多的飞来峰。野外调查发现:这些飞来峰中有的在就位后没有再发生过变形,如分布在兰坪—思茅盆地中段的无量山东北山麓一带的一系列上三叠统灰岩飞来峰;有的飞来峰在就位后再次遭受到强烈的变形,如分布在兰坪盆地金顶一带的上三叠统灰岩飞来峰,在渐新世时与下伏岩层一同卷入了强烈的褶皱变形;分布在大理地区鹤庆盆地西侧的中三叠统灰岩飞来峰因受到后期东西向伸展构造的破坏,已被改造成分选极差的重力滑塌沉积。这些古近纪飞来峰由于在就位后再次发生了变形,所以不应称之为飞来峰,应称为异地岩或者是外来岩块。

福建推覆构造研究

通过地表与深部地球物理资料分析,论证了福建推覆构造的存在,并根据其不同表现形式,划分为东部逆冲推覆带、中部逆冲褶皱带和西部挤压推覆带。在区域构造分析的基础上认为:福建推覆构造发育于印支期,鼎盛发展于燕山早期,定位消减于燕山晚期;推覆运动方向由北西往南东;推覆构造的形成与濒太平洋大陆边缘活动带剧烈运动有关。

四川彭县推覆构造的特征与形成

本文对前龙门山区彭县推覆构造进行了详细研究,在推覆体内部划分出若干不同的构造带,强烈压缩变形的白水河断裂带为其“根带”。它们主要是旱第三纪末的陆内俯冲挤压导致的褶皱-逆冲作用以及随后的重力滑动作用形成的。推覆体在滑移过程中发生变形,并对原地岩系的构造进行改造。

福建推覆构造研究与找矿突破

阐述了福建推覆构造的研究成果,依据福建推覆构造的不同表现形式,划分为东部逆冲推覆构造带、中部逆冲褶皱推覆构造带、西部挤压推覆构造带。讨论了其构造特征形式,将推覆(滑脱)构造形式划分为二类五型及其控岩控矿的地质特征。总结了运用推覆构造研究成果在寻找隐伏煤矿及铁多金属矿的成功实例,提出了推覆构造理论对深部找矿指导作用和找矿方向。

Mesozoic Reservoir Predictionin the Longdong Loess Plateau

This paper summarizes a set of interpretation technologies for Mesozoic sandstone reservoir prediction in the Longdong loess plateau, such as seismic sequence processing and interpretation based on generalized S transform, the eroded paleo-geomorphology interpretation of the top of the Triassic and a variety of lateral reservoir predictions. The effects of employing these technologies are compared and analyzed, as well. The research results show that seismic sequence processing interpretation technology based on generalized S transform can distinguish 3ms (about the thickness of 6 m)sequence interface. Consequently the technology can ascertain the distribution of a sand body of the formation Ch 8 and expand the exploration area of the Xifeng oil field in the Longdong area.

Discussion on origin of clay minerals in outcropped sandstone from Lower Cretaceous Chengzihe Formation and Muling Formation in Jixi Basin

Clay minerals in the outcropped sandstone from Lower Cretaceous Chengzihe Formation and Muling Formation in Jixi Basin were analyzed by X-ray diffraction. The results show that the clay minerals mainly consist of illite, kaollinite and illite/smectite, which can be divided into two types： kaolinite- and illite/smectite types. The outcropped sandstone occurred in middle diagenetic stage-A on the basis of the clay mineral composition. The development factor of the formation of kaolinite type clay mineral is caused mainly by the organic acid from the coal-bearing formation and nmdstone during the diagenesis process in Lower Cretaceous Chengzihe Formation and Muling Formation in the Jixi Basin. The weak hydrodynamic force of sedimentary facies made the sandstone leaching condition poor, which is the reason forming the aggregation of clay minerals of the illite/ smectite-and illite types.

Discussion on bearing capacity of soft rock ground based on in-situ load test

The suitability of five methods was discussed here,taking the typical results from in-situ load test of Renshou Mansion and Caifu Plaza in Yueyang City for example.It shows that bearing capacity can be obtained by the proportion load and limit load from p-s curve with the first and the second point of contraflexure easily.It is recommended that the accurate value of bearing capacity can be obtained by hyperbola fitting method and minimum curvature radius method theoretically.The rebound method is clear in principle,in which the elastoplasticity characteristic is thought about.Out of consideration for the unsteadiness and unobviousness of bearing capacity from relative settlement method,it can be only adopted as reference.So bearing capacity of soft rock ground should be determined by weathering condition of soft rock and curve type.

Prediction Research of Deformation Modulus of Weak Rock Zone under In-situ Conditions

Weak rock zone (soft interlayer, fault zone and soft rock) is the highlight of large-scale geological engineering research. It is an important boundary for analysis of rock mass stability. Weak rock zone has been formed in a long geological period, and in this period, various rocks have undergone long-term consolidation of geostatic stress and tectonic stress; therefore, under in-situ conditions, their density and modulus of deformation are relatively high. Due to its fragmentary nature, once being exposed to the earth's surface, the structure of weak rock zone will soon be loosened, its density will be reduced, and its modulus of deformation will also be reduced significantly. Generally, weak rock zone can be found in large construction projects, especially in the dam foundation rocks of hydropower stations. These rocks cannot be eliminated completely by excavation. Furthermore, all tests nowadays are carried out after the exposure of weak rock zone, modulus of deformation under in-situ conditions cannot be revealed. In this paper, a test method explored by the authors has been introduced. This method is a whole multilayered medium deformation method. It is unnecessary to eliminate the relatively complete rocks covering on weak rock zone. A theoretical formula to obtain the modulus of deformation in various mediums has also been introduced. On-site comparative trials and indoor deformation modulus tests under equivalent density conditions have been carried out. We adopted several methods for the prediction researches of the deformation modulus of weak rock zone under in-situ conditions, and revealed a fact that under in-situ conditions, the deformation modulus of weak rock zone are several times higher than the test results obtained after the exposure. In a perspective of geological engineering, the research findings have fundamentally changed peoples' concepts on the deformation modulus of weak rock zone, provided important theories and methods for precise definition of deformation modulus of deep weak rock zone under cap rock conditions, as well as for reasonable engineering applications.

Oil shale resources in China and their utilization

The unconventional oil and gas resources presented in oil shales have meant these potential sources of hydrocarbons, which has become a research focus. China contains abundant oil shale resources, ranking fourth in the world, with ca. 7 254.48 x 108 t within 24 provinces, including 48 basins and 81 oil shale deposits. A- bout 48% of the total oil shale resources are concentrated in the eastern resource region, with a further 22% in the central resource region. 65 % of the total quantity of oil shale resources is present at depths of 0-500 m, with 17% of the total resources being defined as high-quality oil shales yielding more than 10% oil by weight. Chinese oil shale resources are generally hosted by Mesozoic sediments that account for 78% of the total re- sources. In terms of the geographical distribution of these resources, some 45% are located in plain regions, and different oil shale basins have various characteristics. The oil shale resources in China represent a highly prospective future source of hydrocarbons. These resources having potential use not only in power generation and oil refining but also in agriculture, metal and chemical productions, and environmental protection.

Distinct sedimentary environments and their influences on carbonate reservoir evolution of the Lianglitag Formation in the Tarim Basin,Northwest China

The Upper Ordovician Lianglitag Formation carbonate rocks are important oil and gas reservoirs in the Tarim Basin, Northwest China, with obviously distinct reservoir properties among different oilfields. As a case area of the above carbonate reser- voirs correlation, Tahe and Tazhong oilfields are chosen for the study through an integrated analysis of biostratigraphic isoch- ronous framework, cores, thin sections, logs, and strontium isotopes. The research shows that the two areas were respectively attributed to different carbonate platforms during the Lianglitag Formation depositional phase. For the Lianglitag Formation, five fourth-order sequences may be divided in Tazhong, whereas only four fourth-order sequences are preserved in Tahe that correspond to the lower ones observed in Tazhong. The Lianglitag Formation carbonate platform in Tahe was characterized by ramp and/or weak rimmed types, with low depositional rates （37 ktm/a）, higher whole-rock clastic contents, and higher 878r/86Sr isotope ratios of carbonate matrix, showing relatively deep-water environment and evident terrigenous input for car- bonate deposition. However, a strongly rimmed carbonate platform was developed in Tazhong, with high depositional rates of 250 p.m/a and less whole-rock clastic contents, indicating a high-energy depositional environment. Because of the sedimentary environment differences mentioned above, less high-energy facies but relatively intense syndepositional （early diagenetic） sea-water cementation of carbonates were developed in Tahe, and ubiquitous high-energy reef and shoal facies, with a frequent exposure to subaerial, and weak syndepositional sea-water cementation of carbonates in Tazhong. Therefore, fewer primary pores occurred in the Lianglitag Formation carbonate rocks of Tahe, whereas more primary pores were preserved in the same lithostratigraphic unit of the Tazhong （No. 1 fault zone）. Available high-energy reef-shoal facies and early diagenesis, with more primary pores preserved, provided a key material basis for the Lianglitag Formation carbonate reservoirs that largely oc- curred in Tazhong.

Paleomagnetic results of Late Paleozoic rocks from northern Qiangtang Block in Qinghai-Tibet Plateau, China

Tectonic evolution of the Tethys and the boundary between the Gondwanaland and the Eurasia during the Carboniferous and Permian remain hotly debated. Qiangtang region in the Qinghai-Tibet Plateau may be a key place to study these problems. A paleomagnetic study was conducted on the Late Paleozoic rocks in the northern Qiangtang region （33.7°N, 86.7°W）, Tibet. Two sites （21 samples） in the Upper Carboniferous, eleven sites （101 samples） in the Permian, and two sites （16 samples） in the Lower Triassic were investigated. The rock magnetic data revealed hematite and magnetite as the main magnetic carders. In stepwise thermal demagnetization and/or combined alternating field （AC） demagnetization, two characteristic components in the majority of the samples were identified as （1） the Low-temperature Component （LTC）, characterized by northerly decli- nation and moderate to steep inclination, corresponding to a pole position overlay with the present North Pole. A minority of the samples present single component, and their directions are the same as （2） the High-temperature Component （HTC） of double components. The combined single-component and HTC data of the Permian can pass the R-test at 95% level and the F-test at 99% level, as well as the BC-test. The pole position from the Late Carboniferous is at 31.8°S, 45.7°E with dp=2.1, dm=3.9, that from the Early and Middle （Late） Permian is at 31.7°S, 46.8°E with @=9.2, dm=16.9 （34.4°N, 54.1°E with dp=6.9, dm=1 2.5） respectively, and that from the Early Triassic is at 16.9°S, 22.5°E with dp=4.9, dm=9.2. These pole positions are different from the other poles for the Qiangtang Block, which suggests the single-component and HTC directions are probably a primary magnetization and the northern Qiangtang Block was paleogeographically situated at low latitudes in the Northern Hemisphere in the Late Paleozoic.

Primary dolostone related to the Cretaceous lacustrine hydrothermal sedimentation in Qingxi sag, Jiuquan Basin on the northern Tibetan Plateau

Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1-1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values （C^ISOpDB） range from 5.89%~ to 14.15%o with an average of 9.69%0. The ratio of 87Sr/86Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca2＋, Mg2＋ and Fe2＋. Under the driving flow power of magmatic heat, gravity and compaction, the hy- drothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered ＂hydroexplosion breccias＂. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hy- drotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.

Potential petroleum sources and exploration directions around the Manjar Sag in the Tarim Basin

Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells YM 2 and TD 2 was derived from the Middle-Upper Ordovician and Cambrian source rocks, respectively. We analyzed the biomarkers of the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions from the Lunnan and Hade areas in the North Uplift of the Tarim Basin. Results show that the ratios of tricyclic terpane C2~/C23 in the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions are less than 1.0, indicating that they might be from Upper Ordovician source rocks; the ratios of C28/（C27＋C28＋C29） steranes in the saturated hydrocarbon from reservoir bitumen and bitumen inclusions are higher than 25, suggesting that they might come from the Cambrian source rocks, however, the ratios of C28/（C27＋C28＋C29） steranes in oil from the North Uplift are less than 25, suggesting that they might be sourced from the Upper Ordovician source rocks. These findings demonstrate that the sources of crude oil in the Tarim Basin are complicated. The chemical composition and carbon isotopes of Ordovician reservoired oil in the Tarim Basin indicated that the crude oil in the North Uplift （including the Tahe oilfield） and Tazhong Depression was within mixture areas of crude oil from the Wells YM 2 and TD 2 as the end members of the Cambrian and Middle-Upper Ordovician sourced oils, respectively. This observation suggests that the crude oil in the Ordovician strata is a mixture of oils from the Cambrian and Ordovician source rocks, with increasing contribution from the Cambrian source rocks from the southern slope of the North Uplift to northern slope of the Central Uplift of the Tarim Basin. Considering the lithology and sedimentary facies data, the spatial distribution of the Cambrian, Middle-Lower Ordovician and Upper Ordovician source rocks was reconstructed on the basis of seismic reflection characteristics, and high-quality source rocks were revealed to be mainly located in the slope belt of the basin and were longitudinally developed over the maximum flooding surface during the progressive-regressive cycle. Affected by the transformation of the tectonic framework in the basin, the overlays of source rocks in different regions are different and the distribution of oil and gas was determined by the initial basin sedimentary structure and later reformation process. The northern slope of the Central Uplift-Shuntuo-Gucheng areas would be a recent important target for oil and gas exploration, since they have been near the slope area for a long time.