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| 1 | In Situ Stress Measurements in the Lhasa Terrane,Tibetan Plateau,China显示文摘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. | MENG Wen GUO Changbao ZHANG Yongshuang DU Yuben ZHANG Min BAO Linhai ZHANG Peng | 2016 | Acta Geologica Sinica(English Edition)2016，90，6： | 5 |
| 2 | Wear Properties of Plasma Nitrided H13 Steel at Room and Elevated Temperature显示文摘H13 steel was nitrided using a plasma surface alloying technique at the temperature of 570℃.The nitrided layers with different thicknesses and components were obtained by changing nitriding pressure.The microstructure and composition of the nitrided layers were evaluated by optical microscopy(OM)and X-ray diffraction(XRD).The wear properties of the nitrided layer against Al2O3 ball at room temperature using a ball-on-disc tribometer and against Si3N4 ball at elevated temperature using a HT-2001 abrasive wear test machine were investigated.The results show that the nitrided layers are composed of compound layer and diffusion layer at the pressure of 100 and 450 Pa.No obvious compound layer appears at pressure of 200 and 300 Pa.XRD analysis shows the nitrided layers are mainly composed ofε-Fe2-3N,γ'-Fe4N,α-Fe,Fe2O3 and Fe3O4 phases.The surface hardness of plasma nitrided H13 steel is about 1100HV0.050 doubled that of substrate.The room temperature friction coefficient of H13 steel is reduced and wear rate is decreased by nitriding at 200 and 300 Pa.Elevated temperature wear test indicates the nitrided H13 steel at the pressure of 100 Pa shows lower friction coefficient and wear rate which are reduced more than 6 times compared with that of H13 substrate. | Zhu Ruihua Tian Linhai Bao Mingdong Yong, Ma Bin, Tang | 2012 | 稀有金属材料与工程2012，41，S1： | 1 |
| 3 | Predictive analysis of stress regime and possible squeezing deformation for super-long water conveyance tunnels in Pakistan显示文摘The prediction of the stress field of deep-buried tunnels is a fundamental problem for scientists and engineers. In this study, the authors put forward a systematic solution for this problem. Databases from the World Stress Map and the Crustal Stress of China, and previous research findings can offer prediction of stress orientations in an engineering area. At the same time, the Andersonian theory can be used to analyze the possible stress orientation of a region. With limited in-situ stress measurements, the Hoek–Brown Criterion can be used to estimate the strength of rock mass in an area of interest by utilizing the geotechnical investigation data, and the modified Sheorey's model can subsequently be employed to predict the areas' stress profile, without stress data, by taking the existing in-situ stress measurements as input parameters. In this paper, a case study was used to demonstrate the application of this systematic solution. The planned Kohala hydropower plant is located on the western edge of Qinghai–Tibet Plateau.Three hydro-fracturing stress measurement campaigns indicated that the stress state of the area is SH>-Sh> SVor SH> SV> Sh. The measured orientation of SHis NEE(N70.3°–89°E), and the regional orientation of SHfrom WSM is NE, which implies that the stress orientation of shallow crust may be affected by landforms. The modified Sheorey model was utilized to predict the stress profile along the water sewage tunnel for the plant. Prediction results show that the maximum and minimum horizontal principal stresses of the points with the greatest burial depth were up to 56.70 and 40.14 MPa, respectively, and the stresses of areas with a burial depth of greater than 500 m were higher. Based on the predicted stress data, large deformations of the rock mass surrounding water conveyance tunnels were analyzed. Results showed that the large deformations will occur when the burial depth exceeds 300 m. When the burial depth is beyond 800 m, serious squeezing deformations will occur in the surrounding rock masses, thus requiring more attention in the design and construction. Based on the application efficiency in this case study, this prediction method proposed in this paper functions accurately. | Wang Chenghu Bao Linhai | 2014 | International Journal of Mining Science and Technology2014，24，6： | 0 |
| 4 | Research Progress in Surface and Marine Gravimetry显示文摘Gravity field is the most basic physical field generated by the material properties of the Earth system.It reflects the spatial distribution,movement and change of materials determined by the interaction and dynamic process inside the Earth.Over the years,a variety of technical means have been used to detect the Earth’s gravity field and supported numerous studies on the global change,resource detection,geological structure movement,water resources change and other related fields of research.Here is part of the progress in surface and marine gravimetry obtained by Chinese geodesy scientists from 2019 to 2023 from the following aspects,including:①Continuous gravity network in Chinese mainland;②Application of superconducting gravity measurement;③Network adjustment for continental-scale gravity survey campaign and data quality control;④Regional time-variable gravity field and its application;⑤Research progress on novel technologies for gravity inversion;⑥Research progress on marine gravity field determination;⑦Application research on marine gravity field. | Heping SUN Lifeng BAO Shi CHEN Xiaoming CUI Qianqian LI Lulu JIA Jianqiao XU Jiangcun ZHOU Minzhang HU Yiqing ZHU Xiaodong CHEN Lin WU Jiancheng HAN Honglei LI Miaomiao ZHANG Linhai WANG | 2023 | Journal of Geodesy and Geoinformation Science2023，6，3： | 0 |
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