Reinforcing a Dangerous Rock Mass Using the Flexible Network Method

Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass （e. g. by blasting） needs to be avoided, as this new damage could cause collapse. So the self-bearing capacity of the mountain mass must be used to treat the dangerous rock mass. This article is based on a practical example of the control of a dangerous rock mass at Banyan Mountain, Huangshi, Hubei Province. On the basis of an analysis of damage mechanism and the stability of the dangerous rock mass, a flexible network reinforcement method was designed to prevent the collapse of the rock mass. The deformations of section Ⅱ w of the dangerous rock mass before and after the flexible network reinforcement were calculated using the two-dimensional finite element method. The results show that the maximum deformation reduced by 55 % after the application of the flexible network reinforcement, from 45.99 to 20.75 ram, which demonstrates that the flexible network method is effective, and can provide some scientific basis for the treatment of dangerous rock masses.     

重庆地区江北砾岩地球化学分析

通过选取砾岩填隙物、砾石局部胶结填隙物、砂岩层的鲜岩石作为分析样品,结合江北砂、砾岩碳氧同位素、化学成分和磁化率的特征,对重庆地区江北砾岩进行了地球化学分析.研究结果表明,重庆地区江北砾岩胶结时期为冷干气候占据优势,但也经历了较短的暖湿时期.砾岩的主要成分是硅质,胶结物主要为钙质.     

1-羟基-2-(3,5-二溴-2-吡啶偶氮)-8-氨基-3,6-萘二磺酸的合成及其应用研究

采用常见易得无毒的H-酸为主要原料,在H-酸分子骨架上链接分析功能团,制得了1-羟基-2-(3,5-二溴-2-吡啶偶氮)-8-氨基-3,6-萘二磺酸(3,5-diBrPAH),系统研究了3,5-diBrPAH与Cu2+的显色反应及其应用。实验表明,在pH为8． 0条件下,Cu2+与该试剂形成1:1的络合物,并且稳定时间达5 h,其最大吸收波长为λ=620 nm,表观摩尔吸光系数为3．27 ×104L·mol-1·cm-1,Cu2+浓度在0-25μg／50 mL范围内符合比耳定律。该法可用于矿石及土壤样中微量铜的测定, 简便迅速,结果较令人满意。     

北极新奥尔松地区现代污染源及其指示植物研究

分析了采自北极新奥尔松(Ny-lesund)(78°55′N,11°56′E)煤矿开采区水平剖面12个点位上的三种苔原植物Dicranumangustum(苔藓类植物)、Puccinelliaphryganodes(穗状植物)和Salixpolaris(管状植物)及土壤中10种重金属(Hg、Pb、Cd、Cu、Zn、Ni、Fe、Mn、As、Se)及S、TOC的含量。结果显示采矿过程中煤层的暴露是本地区的Hg、Cd、S污染的主要来源。三种分布最广泛、数量最多的苔原植物中苔藓植物Dicranumangustum对重金属元素具有最大的富集能力,位于矿区的Dicranumangustu体内污染元素含量显著高于非矿区部分,这也说明该水平剖面上的元素污染是由当地煤矿开采导致的。同时发现,Dicranumangustum体内元素积累和土壤中元素浓度之间沿水平剖面的变化趋势较一致,能较好地反映本地区的污染状况,可以作为污染监测和指示植物。从全球区域对比来看,北极新奥尔松苔藓体内污染水平显著低于邻近的北欧等工业区,但却是北极地区Hg、Cd和S污染最严重地区,同时也比南极地区高。     

水文变异的滑动F识别与检验方法

针对传统F检验法只能用于已知变异点的检验,而无法用于变异点的识别问题,本文提出了滑动F识别与检验法。该法首先利用传统F检验法对序列逐点进行检验,找出满足F计算值大于临界值的所有可能变异点,然后选择F计算值达到最大值的那一点作为最可能变异点。利用该法对潮白河水资源分区45年年径流量序列进行了分析,并从物理成因角度对该检验结果进行了确认。结果表明滑动F 识别与检验法具有较好的检验效果,检验结果可信度较高。     

Recent tectonic stress field zoning in Sichuan-Yunnan region and its dynamic interest

In this paper, we have carefully determined the stress zones in the Sichuan-Yunnan region with reference to the in-situ stress data of hydraulic fracturing and the inverted fault slip data by using the step-by-step convergence method for stress zoning based on focal mechanism solutions. The results indicate that the tectonic stress field in the Sichuan-Yunnan region is divided into 3 stress zones by 2 approximately parallel NNW-trending stress transition belts. The area between the 2 belts is the Sichuan-Yunnan stress zone where the maximum principal stress σ1 is just in the NNW direction. The eastern boundary of Sichuan-Yunnan stress zone （the eastern stress transition belt） is basically consistent with the eastern boundary of Sichuan-Yunnan rhombic block. The western boundary of Sichuan-Yunnan stress zone （the western stress transition belt） is not totally consistent with the western boundary of Sichuan-Yunnan rhombic block. The northern segment of the western stress transition belt extends basically along the Jinshajiang fault and accords with the western boundary of Sichuan-Yunnan rhombic block, while its southern segment does not extend along the southwestern boundary of the rhombic block, i.e., Honghe fault and converge with the eastern stress transition belt, but stretches continuously in the NNW direction and accords with the Yingpanshan fault. We therefore consider that under the combined influence from the northward motion of India Plate, the southeastward shift of east Qinghai-Xizang Plateau and the strong obstruction of South China block, the tectonic stress field in the Sichuan-Yunnan region might not be totally controlled by the previous tectonic frame and new stress transition belt may have possibly formed.     

Landslide and debris-flow hazard analysis and prediction using GIS in Minamata–Hougawachi area, Japan

On July 20, 2003, following a short duration of heavy rainfall, a debris-flow disaster occurred in the Minamata–Hougawachi area, Kumamoto Prefecture, Japan. This disaster was triggered by a landslide. In order to assess the landslide and debris-flow hazard potential of this mountainous region, the study of historic landslides is critical. The objective of the study is to couple 3D slope-stability analysis models and 2D numerical simulation of debris flow within a geographical information systems in order to identity the potential landslide-hazard area. Based on field observations, the failure mechanism of the past landslide is analyzed and the mechanical parameters for 3D slope-stability analysis are calculated from the historic landslide. Then, to locate potential new landslides, the studied area is divided into slope units. Based on 3D slope-stability analysis models and on Monte Carlo simulation, the spots of potential landslides are identified. Finally, we propose a depth-averaged 2D numerical model, in which the debris and water mixture is assumed to be a uniform continuous, incompressible, unsteady Newtonian fluid. The method accurately models the historic debris flow. According to the 2D numerical simulation, the results of the debris-flow model, including the potentially inundated areas, are analyzed, and potentially affected houses, river and road are mapped.     

Sulfur Isotope Geochemistry of the Supergiant Xikuangshan Sb Deposit, Central Hunan, China: Constraints on Sources of Ore Constituents

Abstract. The supergiant Xikuangshan Sb deposit is located in the Middle to Upper Devonian limestone of central Hunan, China. Primary ores are composed of early-stage stibnite and calcite with rare pyrite, early main-stage stibnite and quartz, and late main-stage stibnite and calcite. New sulfur isotope data reveal the clustering of δ³⁴S values (+5 ∼ +8 %) for both early and late main-stage stibnite; a single early-stage stibnite exhibits δ³⁴S value (+7.5 %) identical to its main ore-stage counterparts and the coexisting calcite has almost unmodified carbon isotope composition (-4.4 %). The data suggest a probable common source of sulfur for stibnite that was deposited at different paragenetic stages. A much wider variation in δ³⁴S values for early main-stage stibnite (+3.5 to +16.3 %, av. +7.5 %) compared to that for late main-stage stibnite (+5.3 to +8.1 %, av. +6.2 %) can be interpreted to be due to local interaction of earlier ore fluid with Devonian host rocks. The previous studies show that the Precambrian basement contains elevated Sb concentrations, and two distinctive sulfur reservoirs with δ³⁴S_pyrite values at ca. +11 ∼ +24 % and -7.0 ∼-11 %. The homogenizing effect for sulfur hydrothermally leached from the two reservoirs might have provided ore constituents for the Xikuangshan fluids.     

Nutrient fluxes induced by disturbance in Meiliang Bay of Lake Taihu

A wave flume experiment was conducted to study nutrient fluxes at water-sediment interface of Meiliang Bay under different hydrodynamic conditions. The results reveal that hydrodynamics has remarkable effects on nutrient fluxes in this area. With a bottom wave stress of 0.019 N m^?2 (equivalent to disturbance caused by wind SE 5–7 m s^?1 at the sediment sample site of Meiliang Bay), the fluxes of TN, TDN and NH₄ ⁺-N were separately 1.92 × 10^?3, ?1.81 × 10^?4 and 5.28 × 10^?4 mg m^?2 s^?1 (positive for upward and negative for downward), but for TP, TDP and SRP, the fluxes were 5.69 × 10^?4, 1.68 × 10^?4 and ?1.29 × 10^?4 mg m^?2 s^?1. In order to calculate the released amount of nutrients based on these results, statistic analysis on the long-term meteorological data was conducted. The result shows that the maximum lasting time for wind SE 5–7 m s^?1 in this area is about 15 h in summer. Further calculation shows that 111 t TN, 32 t NH₄ ⁺-N, 34 t TP and 10 t TDP can be released into water (the sediment area was 47.45% of the whole surface area), resulting in concentration increase of 0.025, 0.007, 0.007 and 0.002 mg L^?1 separately. With stronger disturbance (bottom wave stress is 0.217 N m^?2 which is equivalent to disturbance caused by wind SE 10–11 m s^?1 at the same site), there has been significant increase of nutrient fluxes (1.16 × 10^?2, 6.76 × 10^?3, 1.14 × 10^?2 and 2.14 × 10^?3 mg m^?2 s^?1 for TN, DTN and NH₄ ⁺-N and TP). The exceptions were TDP with flux having a decrease (measured to be 9.54 × 10^?5 mg m^?2 s^?1) and SRP with flux having a small increase (measured to be 5.42 × 10^?5 mg m^?2 s^?1). The same statistic analysis on meteorological data reveal that the maximum lasting time for wind SE 10–11 m s^?1 is no more than 5 h. Based on the nutrient fluxes and the wind lasting-time, similar calculations were also made suggesting that 232 t TN, 134.9 t TDN, 228 t NH₄ ⁺-N, 42.7 t TP, 2.0 t TDP and 1.1 t SRP will be released from sediment at this hydrodynamic condition resulting in the concentration increases of 0.050, 0.029, 0.049, 0.009, 0.0004 and 0.0002 mg L^?1. Therefore in shallow lakes, surface disturbance can lead to significant increase of nutrient concentrations although some components in water column had negative flux with weak disturbance (e.g. TDN and SRP in this experiment). In this case, sediment looks to be a source of nutrients. These nutrients deposited in sediment can be carried or released into water with sediment resuspension or changes of environmental conditions at water-sediment interface, which can have great effects on aquatic ecosystem and is also the characteristics of shallow lakes.     

场地地震安全性评价中确定设计地震动参数若干问题研究

本文研究确定设计地震动参数中涉及的若干问题,其中包括基岩水平加速度反应谱衰减关系的选择、震源深度对基岩水平加速度峰值及基岩反应谱曲线的影响、强度包络线函数及输入随机相位的选择、土体非线性特性参数和土层剪切波速值的选择、设计地震动反应谱的标定等问题。本文基于一个典型场地计算剖面,采用一维等效线性化模型并通过逐项变换某些研究参数的方法,研究了各种因素对设计地震动参数可能产生的影响及存在的误差和相应的规律。