塔里木盆地中—下奥陶统层序地层研究

运用地震、测井等手段,结合岩石学、生物地层学地层对比方法,将塔里木盆地中—下奥陶统层序划分为1个二级层序(SSQ6),4个三级层序:SQ1、SQ2、SQ3、SQ4。对层序地层、沉积相特征研究发现,构造运动、海平面升降和古气候变化为塔里木盆地中—下奥陶统层序发育主要控制因素。     

甘肃龙首山地区芨岭铀矿床隐爆角砾岩发现及成因探讨

钠交代岩型铀矿是甘肃龙首山地区主要的铀成矿类型之一,研究表明该类型铀矿的含矿主岩为热液隐爆钠交代角砾岩,其分布总体上受近东西向断裂及其分支断裂控制,呈带状分布,构成不规则状的隐爆钠交代角砾岩带。在剖面上,隐爆钠交代角砾岩呈筒状或漏斗状,其控制了钠交代岩型铀矿体的分布。文章认为它是由花岗质岩浆房产生的富气富钠热液运移至压力骤减部位时,发生爆腾形成隐爆钠交代角砾岩,碳酸铀酰络合物([UO2(CO3)]4-)分解卸载成矿物质成矿,同时对围岩产生了钠长石化、绿泥石化、碳酸盐化、赤铁矿化、泥化和硅化。指出按隐爆钠交代角砾岩型找矿模式对该区下一步找矿工作具有较大的指导意义。     

2000年苏门答腊M_S8.0地震对缅甸M_S6.5地震动态应力触发作用及影响因素

根据地震动态触发理论,计算了2000年苏门答腊MS8.0,地震在缅甸MS6.5地震破裂面上产生的动态库仑应力:正峰值为1.357 5 MPa,负峰值为-1.113 5 MPa。峰值大于地震触发阈值0.01 MPa,苏门答腊地震的发生对缅甸地震具有一定的触发作用。在计算过程中发现,主震基本参数、传播过程中介质参数和被触发地震断层参数的准确性对计算结果有较大影响。     

基于ARCGIS的土地开发潜力测算与分级——以宝鸡市陇县为例

土地开发潜力评价是科学开展土地开发工作的基础,影响土地开发潜力的因素众多,目前还没有公认比较成熟的评价理论与方法。结合陇县的实际情况,提出以增加耕地系数、增加耕地面积和未利用地区位指数三个指标结合评价土地开发潜力测算,以乡镇为分级单元在科学地定量评价土地开发潜力的基础上,对陇县的土地开发潜力进行分级,为土地开发整理工作提供判断依据。     

Study on rain-runoff process in the peripheral mountainous area of the Sichuan Basin

Studies on rain-runoff process in the peripheral mountainous area of the Sichuan Basin, which is regarded as a key ecological shelter, will contribute to flood control and environmental protection for the Upper Yangtze River Basin. In two typical catchments--the Fujiang River Catchment and the Wujiang River Catchment, rainfall simulations have been conducted to study the rain-runoff processes of yellow soil and limestone soil in three types of land use--forestland, farmland and grassland. Results showed that （1） within the same rainfall process, overland flow occurs first on farmland, then on grassland, and finally on forestland; （2） soil surface coverage has a great impact on the occurrence and amount of overland flow. The runoff amount can increase 2-4 times after the coverage is removed; （3） the infiltration before the occurrence of overland flow will decrease because of higher gravel contents of soil, but it takes no effect on infiltration once overland flow becomes stable; （4） the runoff coefficient of the limestone soil forestland is greater than that of the yellow soil forest land, but less than that of the farmland; （5） three empirical infiltration models, including Horton＇ model, Kostiakov＇ model, and modified Kostiakov＇ model, were compared by using the observed results under rainfall simulation. The results showed that the Kostiakov＇ model performed better than both the Horton＇ model and modified Kostiakov model. According to the results of this research, the Kostiakov＇s model can be used to simulate rainfall infiltration when water erosion is modeled in the peripheral mountainous area of the Sichuan Basin.     

Wenchuan Earthquake： Way of thinking is changed

On 12 May, 2008, at 14：28：04 local time, an Ms 8.0 earthquake struck the Wenchuan County, Sichuan Province, in southwest China （Figure 1）. This quake left about 70,000 people dead, 18,000 missing and over 370,000 injured. In the 75 days after the main shock, 20,000 aftershocks were recorded, which included 241 with Ms≥4.0, 205 with 4.0≤M≤4.9, 30 with 5.0≤Ms≤5.9, and 6 with Ms≥6.0. The largest aftershock took place 13 days after the main shock, in Qingchuan County, 110 km northeast of the epicenter of the quake （Chen, 2008）. The losses from the quaketriggered geological disasters accounted for over a third of the total quake losses, which is extremely rare in the history of earthquake disasters. Secondary disasters, such as landslides, rockslides, landfalls, debris flows, etc., were widely distributed. Large numbers of buildings collapsed, including ones with steel reinforcing in the area of the epicenter. Infrastructure was badly damaged. In many areas, communications, and power and water supplies were cut off. The earthquake left over 35 large quake-dammed lakes, which threatened further disasters in the catchment areas.     

改进BP神经网络在岩质边坡稳定性分析中的应用

使用MATLAB软件中的NNtool工具箱建立了一个通过添加动量改进的BP神经网络模型,用以分析岩质边坡的稳定性。通过对天津某工程的边坡进行分析来检验这个模型的可靠度。根据现场调查的实际情况分析,该边坡岩体比较破碎,因此文中选择了几个有代表性的岩石完整性参数作为输入层参数,通过收集的一些类似边坡的参数对所建立的神经网络模型进行训练,以保证此模型适合被用来分析该工程。结果证明,所建立的模型是可靠的,此种方法在分析岩质边坡稳定性的的实践中具有广泛的使用性。     

Case study of a giant debris flow in the Wenjia Gully, Sichuan Province, China

The debris flow, which was triggered in the Wenjia Gully on August 13, 2010, is an extreme example of mass movement events, which occurred after the Wenchuan earthquake of May 12, 2008. This Earthquake triggered in the Wenjia Gully the second largest co-seismic landslide, which can be classified as a rockslide-debris avalanche. A lot of loose sediments was deposited in the basin. In the main so called Deposition Area II of this landslide, with a volume of 30?×?10⁶?m³, flash floods can easily trigger debris flows because of the steep bottom slope and the relative small grain sizes of the sediments. The largest debris flow of August 13, 2010 destroyed the most downstream dam in the catchment during a heavy rain storm. The debris flow with a peak discharge of 1,530?m³/s and a total volume of 3.1?×?10⁶?m³ caused the death of 7 persons, 5 persons were missing, 39 persons were injured and 479 houses buried. After three rainy seasons, only 16?% of the landslide-debris deposition was taken away by 5 large-scale debris flow events. Since the threshold for rainfall triggered debris flows in the Wenjia Gully and other catchments drastically decreased after the Wenchuan Earthquake, new catastrophic events are expected in the future during the rainy season.     

川西龙泉山西坡更新世泥石流的发现及其意义

在川西地区龙泉山西坡首次发现了第四纪泥石流沉积。泥石流沉积相组合为AA1B、AA1C、AA1,反映泥石流为洪积扇扇中沉积组合,具有粘性泥石流的沉积特征。ESR测年及孢粉化石组合特征表明泥石流沉积于早-中更新世温暖湿润的气候环境下。龙泉山泥石流的形成反映了龙泉山早-中更新世之交的构造隆升,以及四川盆地盆地期夷平面的解体,是对早-中更新世之交青藏高原的隆起、季风的加强、暴雨式降水出现的沉积响应,对于研究四川盆地西部及青藏高原东缘第四纪构造运动及古气候特征具有重要的意义。     

A formation model for debris flows in the Chenyulan River Watershed, Taiwan

Many debris flows were triggered in the Chenyulan River Watershed in Taiwan in a rainstorm caused by the Typhoon Toraji. There are 117 gullies with a significant steep topography in the catchment. During this Typhoon, debris flows were initiated in 43 of these gullies, while in 34 gullies, it was not certain whether they have occurred. High-intensity short-duration rainfall was the main triggering factor for these gully type debris flows which are probably entrained by a “fire hose” mechanism. Previous research identified 47 factors related to topography, geology, and hydrology, which may play a role in the formation of gully type debris flows. For a better understanding of the probability of the formation of debris flows, it is proposed to represent the factors related to topography, geology, and hydrology by one single factor. In addition to the existing topographic and geological factor, a normalized critical rainfall factor is suggested with an effective cumulative precipitation and a maximum hourly rainfall intensity. In this paper, a formation model for debris flows is proposed, which combines these topographic, geological, and hydraulic factors. A relationship of these factors with a triggering threshold is proposed. The model produces a good assessment of the probability of occurrence of debris flows in the study area. The model may be used for the prediction of debris flows in other areas because it is mostly based on the initiation mechanisms and not only on the statistical analyses of a unique variety of local factors. The research provides a new and exciting way to study the occurrence of debris flows initiated by a “fire hose” mechanism.