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  • 14C dating of Holocene volcanic rocks of the Jingpohu Region, Heilongjiang Province, and characteristics of their source regions

    • 摘要:

      Holocene volcanoes of the Jingpohu region, Heilongjiang Province, are situated i Three gagatite samples from the strata of the first and second sub-cycles of Nos. I and V (Daganpao) craters of the 'Crater Forest' and the first sub-cycle of No. XII crater of the 'Frog Pool' respectively were used for 14C dating. The dating results are 3430±60, 2470±120, 2470 ±110 and 3490±140 years respectively (the gagatite sample collected from No. V crater was measured twice). Based on the existence of three volcanic sub-cycles in the study area, as well as the geological characteristics and the oldest age of the trees in the study area, it is inferred that the last volcanic eruption happened about 2000 years to 1000 years ago. The interval of two eruptions is about 1000 years. It shows that the Jingpohu volcano is one of the most dangerous volcanoes in Northeast China. Great differences in petrological and geochemical characteristics of the basaltic rocks and mantle inclusions between the 'Crater Forest' and the 'Frog Pool' show the extreme heterogeneity of the mantle source beneath the Jingpohu region 3490 years ago. It was probably related to the third-class activity of the mantle plume beneath the area.

    • 作者:

      Zhang Z.;Li Z.;Li S.;Xin Y.;Wang X.;Yin J.

    • 刊名:

      Acta Geologica Sinica

    • 在线出版时间:

      2000

  • Discovery of a special type of leucite tephrite in Jingpohu region of Heilongjiang Province and its significance

    • 摘要:

      A special type of leucite tephrite is discovered in the "Frog Pool" area northwest Jingpohu region of Heilongjiang Province. Their petrochemistry indicates a weak agpaitic rock, containing the megacrysts of kaersutite, phlogopite and anorthoclase. Compared with alkali olivine basalts from the "Crater Forest" area 15 km away from "Frog Pool", it is totally characterized by higher contents of Al 2 O 3 (16.73%∼18.09%), Na 2 O (5.15%∼6.36%), K 2 O(4.24%∼4.92%) and stronger enrichment in LREE and LILE, and lower contents of MgO(4.19%∼4.59%), CaO(5.66%∼5.85%), Mg # value (0.43-e10.50). The leucite tephrite is formed by the fractional crystallization in deep depth of the primitive magma which is lowly melted from the lithosphere mantle strongly metasomatized by mantle plume materials enriching in H 2 O, F and other volatile components based on its geological settings and Sr, Nd Pb isotopic compositions.

    • 作者:

      Zhang Z.;Li Z.;Li S.;Xin Y.;Wang X.

    • 刊名:

      Scientia Geologica Sinica

    • 在线出版时间:

      2001

  • Petrochemical study of the Jingpohu Holocene alkali basaltic rocks, northeastern China

    • 摘要:

      Holocene volcanoes in the Jingpohu region are situated in the "Crater Forest" and "Frog Pool" areas along the northwest side of Jingpohu Lake, northeastern China. Dating of three charcoal samples from the first and second volcanic cycles shows that the ages of the first and second cycles are 3430~3490 and 2470 years respectively. The lavas from the Jingpohu area consist of basanites (BSN), alkali olivine basalts (AOB) and tephrites (TP). Crystal fractionation models are consistent with the generation of AOB and TP from a basanitic parent. Minor fractionation of olivine, augite, magnetite and Cr-spinel is required to produce AOB compositions whereas the generation of TP requires extensive fractionation of kaersutite. phlogopite and anorthoclase with minor olivine, augite, magnetite and leucite. The presence of kaersutite, phlogopite and anorthoclase megacrysts and mantle xenoliths suggest a fractionation history occurring at high pressure in the mantle. Although all basaltic rocks contain many granitic xenoliths, their geochemical characteristics show that they have not undergone any contamination of upper crust en route to the surface, but some alkali basalts were suffered from the contamination of lower crust. Relatively unradiogenic isotope ratio (compared with Bulk Earth), steep chondrite-normalized REE patterns and strong incompatible element enriched patterns suggest that the magmas are derived from a mixture of an incompatible element depleted anhydrous Iherzolite asthenospheric mantle source and an enriched, amphibole-phologite-(apatite-) bearing Iherzolite continental lithospheric mantle source. We propose that the basanites are the products of very low degree partial melts (<1%) of this source under high extension strength.

    • 作者:

      Zhang Zhaochong;Feng Chengyou;Li Zhaonai;Li Shucai;Xin Ying;Li Zhaomu;Wang Xianzheng

    • 刊名:

      Geochemical Journal

    • 在线出版时间:

      2002

  • Brittle elastoplastic damage constitutive model for jointed rockmasses and computation concerning bolt-reinforcement

    • 摘要:

      The present paper puts forward a 3D brittle elastoplastic damage fracture constitutive model (BEPDFC model) for jointed rockmass, which is established according to the evolution equation for energy damage of rock fissures, the generalized orthogonal flow rule and the conformability conditions of plastic damage. On the basis of this constitutive model, a cylindrical damage rock-bolt element model (CDRBE model) is proposed to simulate the reinforcing effect of bolts. Finally, the proposed models are applied to the stability analysis of the high slopes of ship lock of Three Gorges Project being under construction. The 3D nonlinear FEM analysis on the jointed rockmass of high slopes gives satisfactory results.

    • 作者:

      Zhu Weishen;Zhang Qiangyong;Li Shucai;Lee C. F.

    • 刊名:

      International Journal of Damage Mechanics

    • 在线出版时间:

      2003

  • Analysis of fluid-solid coupling for slope stability of cofferdam in water

    • 摘要:

      The paper chiefly deals with the given method of the characteristic time and fluid boundary condition in the analysis course of the fluid-solid couple, which is applied to analyze the couple of fluid-solid of the cofferdam of Tai'an Pumped Storage Power Station. At the same time, it studies the influence of the foundation excavation on the stability of the cofferdam and the slope of the foundation. For the sake of giving the fluid-flow boundary and the proper characteristic time in the excavating process, the last result makes clear the distinct drop of the pore pressure in the cofferdam and foundation. The reason is, firstly, the enlargement of fluid-flow boundary after the excavation and, secondly, the lengthenment of the fluid-flow time in the computation. Those indicate the importance of the characteristic time and fluid boundary in the course of the fluid-solid couple analysis.

    • 作者:

      Li Shu-Chen;Li Shu-Cai;Zou Shu-Ping

    • 刊名:

      Yantu Lixue Rock and Soil Mechanics

    • 在线出版时间:

      2004

  • Brittle damage and coalescence model of jointed rock mass

    • 摘要:

      Based on equivalent energy theory, the anisotropy damage constitutive model of jointed rock mass is set up with joint surface closing and friction considered. The flexibility tensor and its increments are deduced. The FEM with the new constitutive model has been applied to analyze the stability of a planed two-lane subsea road tunnel between the mainland and island in Xiamen city, China. Damage evolution zone of fractures, plastic zone and deformation of rock mass due to excavation are obtained from numerical results.

    • 作者:

      Chen W. Z.;Li S. C.;Qiu X. B.;Yang C. H.;Wang G. G.

    • 刊名:

      Key Engineering Materials

    • 在线出版时间:

      2004

  • Displacement back analysis research on bolt-grouting supporting parameter of rock mass in jointed rock roadway

    • 摘要:

      The method of bolt-grouting supporting, grouting into surrounding rock mass by bolts in jointed rock mass roadway, is obtained wide application. However, it is difficult to determine rock mass parameter of bolt-grouting supporting. This paper begins with the displacement, which is measured easily in practice. The method of back analysis is adopted to calculate the equivalent mechanics parameters of bolt-grouting rock mass. In process of back analysis three mechanics models is supposed which are homogeneous elastic model, inhomogeneous elastic model and elastic-plastic model and corresponding algorithm is established. What's more, this paper discusses the stability of inverse algorithm and copes the problem of back analysis parameter probably instable with QR decomposed algorithm and singular value decomposed algorithm, which will be a theoretical base to determine the mechanics parameter of bolt-grouting supporting rock mass and to estimate the surrounding rock stability. In a word, the method is established to estimate mechanics parameters of bolt-grouting jointed surrounding rock mass, and some significant results are obtained, which are of reference for actual project.

    • 作者:

      Zhang Lewen;Li Shucai;Li Shuchen

    • 刊名:

      Key Engineering Materials

    • 在线出版时间:

      2004

  • Application of energy damage reinforcement model in landslide treatment

    • 摘要:

      According to energy damage anchoring mechanism, an energy damage reinforcement model is proposed to simulate reinforcing effect of bolts in jointed rock masses. After carefully analyzing causes of landslide, the model is applied to Dananshan Landslide which is the largest geological hazard so far in Shenzhen and remarkable economic effect is obtained.

    • 作者:

      Zhang Qiangyong;Xiang Wen;Li Shucai;Zhu Weishen

    • 刊名:

      Yanshilixue Yu Gongcheng Xuebao Chinese Journal of Rock Mechanics and Engineering

    • 在线出版时间:

      2004

  • Application of fracture failure strength model to support for large scale oil-depot rock slope

    • 摘要:

      There are lots of pore spaces, joint planes and cracks, and they are a kind of initial damage in rock mass. It is the initial damage, damage evolution and propagation fracture that result in various failure of jointed rock mass. The influence of crack propagation process and interaction of cracks on rock mass strength is systematically studied according to propagating-fracture mechanism of jointed cracks. A fracture failure strength model for jointed rock mass is established, and applied to guide reinforcement design for a high rock mass slope at Dawan oil depot in Guangdong Province. Some satisfactory computational results are obtained and remarkable economic benefits are achieved from the model.

    • 作者:

      Zhang Qiangyong;Li Shucai;Chen Weizhong

    • 刊名:

      Yanshilixue Yu Gongcheng Xuebao Chinese Journal of Rock Mechanics and Engineering

    • 在线出版时间:

      2004

  • Research on saturated and unsaturated flow mechanism of claystone

    • 摘要:

      Coupled unsaturated flow in claystone has high effect on strength and stability of underground engineering. Based on experimental results of unsaturated flow in claystone, mechanical and unsaturated flow coupled constitutive model is applied to simulate the shrinkage and swelling phenomena in claystone tunnel during excavation, concrete support and ventilation processes. The whole flow process in claystone from state of saturated to desaturated state and then to resaturated state is obtained from the numerical results. The achievements are quite useful to explain the argillization and collapse mechanism in practice, and have great theoretical and practical significance.

    • 作者:

      Chen Weizhong;Yang Chunhe;Li Fei;Li Shucai;Shao Jianfu;Su Kun

    • 刊名:

      Yanshilixue Yu Gongcheng Xuebao Chinese Journal of Rock Mechanics and Engineering

    • 在线出版时间:

      2004

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