Experimental Research of Reinforced Concrete Buildings Struck by Debris Flow in Mountain Areas of Western China

It＇s very important to simulate impact load of debris flow effectively and to investigate dynamic response of architectures under dynamic impact of debris flow, which are necessary to design disaster mitigation construction. Firstly, reinforced concrete domestic architectures in mountain areas of western China had been chosen as main architecture style. The bearing load style and the destructed shape of reinforced flamed construction impacted by discontinuous viscous debris flow were studied systematically. Secondly, Jiangjia Ravine debris flow valley in Yunnan Province, China had been chosen as research region. Utilizing based data from fieldwork and practical survey, the authors simulated and calculated theoretically impact force of discontinuous viscous debris flow. Thirdly, an impact data collecting system （IMHE IDCS） was designed and developed to fulfill designed simulation experiments. Finally, a series of impact test of researched structure models had been fulfilled. During experiment, the destructed shape and course of models were observed and the dynamic displacement data and main natural frequency data of models were collected and analyzed.     

Self－organization criticality of debris flow rheology

Based on the viewpoint of stress and strain serf-organization criticality of debris flow mass, this paper probes into inter-nonlinear action between different factors in the thixotropic liquefaction system of loose clastic soil on slope to make clastic soil in slope develop naturally towards critical stress status, and slope debris flow finally occurs under trigging by rainstorm. Also according to observation and analysis of self-organization criticality of sediment runoff system of viscous debris flow surges in ravines and power relation between magnitude and frequency of debris flows,this paper expounds similarity of the self-organized structure of debris flow mass. The self-organized critical system is a weak chaotic system. Debris flow occurrences can be predicted accordingly by means of observation at certain time scale and analysis of self-organization criticality of magnitude, frequency and time interval of debris flows.     

Using Fuzzy Relations and GIS Method to Evaluate Debris Flow Hazard

The study area, located in the southeast of Tibet along the Sichuan-Tibet highway, is a part of Palongzangbu River basin where mountain hazards take place frequently. On the ground of field surveying, historical data and previous research, a total of 31 debris flow gullies are identified in the study area and 5 factors are chosen as main parameters for evaluating the hazard of debris flows in this study. Spatial analyst functions of geographic information system （GIS） are utilized to produce debris flow inventory and parameter maps. All data are built into a spatial database for evaluating debris flow hazard. Integrated with GIS techniques,the fuzzy relation method is used to calculate the strength of relationship between debris flow inventory and parameters of the database. With this methodology,a hazard map of debris flows is produced. According to this map,6.6% of the study area is classified as very high hazard, 7.3% as high hazard,8.4% as moderate hazard,32. 1% as low hazard and 45.6% as very low hazard or non-hazard areas. After validating the results, this methodology is ultimately confirmed to be available.     

Regional Prediction of Impending Debris Flow Based on Doppler Weather Radar

Debris flow prediction is one of the important means to reduce the loss caused by debris flow. This paper built a regional prediction model of impending debris flow based on regional environmental background （including topography, geology, land use, and etc.）, rainfall and debris flow data. A system of regional prediction of impending debris flow was set up on ArcGIS 9.0 platform according to the model. The system used forecast precipitation data of Doppler weather radar and observational precipitation data as its input data. It could provide a prediction about the possibility of debris flow one to three hours before it happened, and was put into use in Liangshan Meteorological Observatory in Sichuan province in the monsoon of 2006.     

Debris Flow Hazard Assessment Based on Support Vector Machine

Seven factors, including the maximum volume of once flow , occurrence frequency of debris flow , watershed area , main channel length , watershed relative height difference , valley incision density and the length ratio of sediment supplement are chosen as evaluation factors of debris flow hazard degree. Using support vector machine （SVM） theory, we selected 259 basic data of 37 debris flow channels in Yunnan Province as learning samples in this study. We create a debris flow hazard assessment model based on SVM. The model was validated though instance applications and showed encouraging results.     

A mathematical model and numerical simulation of pressure wave in horizontal gas-liquid bubbly flow

By using an ensemble-averaged two-fluid model,with valid closure conditions of interfacial momentum exchange due to virtual mass force,viscous shear stress and drag force,a model for pressure wave propagation in a horizontal gas-liquid bubbly flow is proposed.According to the small perturbation theory and solvable condition of one-order linear uniform equations,a dispersion equation of pressure wave is induced.The pressure wave speed calculated from the model is compared and in good agreement with existing data.According to the dispersion equation,the propagation and attenuation of pressure wave are investigated systemically.The factors affecting pressure wave,such as void fraction,pressure,wall shear stress,perturbation frequency,virtual mass force and drag force,are analyzed.The result shows that the decrease in system pressure,the increase in void fraction and the existence of wall shear stress,will cause a decrease in pressure wave speed and an increase in the attenuation coefficient in the horizontal gas-liquid bubbly flow.The effects of perturbation frequency,virtual mass and drag force on pressure wave in the horizontal gas-liquid bubbly flow at low perturbation frequency are different from that at high perturbation frequency.     

A non-commutative time-frequency tomography

The characterization of non-stationary signal requires joint time and frequency information. However, time and frequency are a pair of non-commuting variables that cannot constitute a joint probability density in the time-frequency plane. The time-frequency distributions have difficult interpretation problems arising from negative and complex values or spurious components. In this paper, we get time-frequency information from the marginal distributions in rotated directions in the time-frequency plane. The rigorous probability interpretation of the marginal distributions is without any ambiguities. This time-frequency transformation is similar to the computerized axial tomography (CT or CAT) and is applied to signal analysis and signal detection and reveals a lot of advantages especially in the signal detection of the low signal/noise (S/N).     

综合利用水电站水库■流调节的数值解法(英文)

The Numerical Solution of the Flow Regulation of theWater Power Station of Multipurpose Utilization ReservoirChen ShouyuStream flow regulation is one of the most important technical measures indeveloping water resources and in controlling river system. To constructreservoirs on a river to regulate the runoff is an active way to reconstructthe natural water resources. In order to realize such an engineering measure,one must investigate the theory and method of flow regulation, so as to get…     

Method and its application of the momentum model for debris flow risk zoning

In order to ascertain the distribution of flow depth and veloctiy of debris flow,the the combination of numerical modeling and the GIS technology has been used to simulate the movement process of debris flow out of the outlet .The main model of momentum classification of risk zoning of debris flow is Z=Khv,Based on the distribution of the veloctiy and depth of debris flow ,the ditribution of momentum can be ascertained.Thereby the classification of risk zoning of debris flow can be worked out ,A case study of Chacatio Valley in Caracas,Venezuela,is presented to illus-trate the application of the method.     

Response of water budget to recent climatic changes in the source region of the Yellow River

Discharge in the source region of the Yellow River significantly declined after 1990.China Meteorological Administration(CMA) data show that precipitation in this region was low in the 1990s but returned to above normal after 2002;in recent decades there has been rapid warming of surface air,moistening and wind speed decrease.To investigate the influences of recent climatic changes on the water budget,this study simulates the surface water budget at CMA stations within and surrounding the source region during 1960-2006,using an improved land surface model.Results indicate that the spatial pattern of precipitation change is an important factor(except for precipitation amount and intensity) in determining the response of runoff to precipitation changes.Low runoff in the 1990s was consistent with precipitation amount and intensity.The recovery of precipitation after 2002 is mainly from increased precipitation in the dry area of the source region.Evaporation was mainly limited by water availability in this dry area,and thus most of the precipitation increase was evaporated.By contrast,energy availability was a more important influence on evaporation in the wet area.There was more evaporation in the wet area because of rapid warming,although precipitation amount partly decreased and partly increased,contributing to the reduction of runoff after 2002.This control on evaporation and its response,together with the modified spatial pattern of precipitation,produced a water budget unfavorable for runoff generation in the source region during recent years.     

基于树木年代学的冰川型泥石流灾害历史重建方法-以西藏天摩沟为例

藏东南帕隆藏布流域冰川型泥石流规模大、数量多。天摩沟是帕隆藏布左岸一级支流,最近20年多次爆发冰川型泥石流,重复堵江并形成长1.5 km左右的堰塞湖。冰川型泥石流事件爆发时间和规模的确定对山区泥石流防灾减灾意义重大。本文基于树木年代学方法,通过分析树木年轮损伤组织、生长抑制和释放动态,重建天摩沟60年来的泥石流事件的时空分布;从树木生长扰动强度等方面探讨泥石流的流动范围和沟道溯源侵蚀过程;并通过Wit指数进一步分析泥石流发生时间和日降雨及气温之间的关系。结果表明天摩沟在1965、1970、1976、2007、2010和2018年爆发过泥石流,与2007年以来的有记录的泥石流事件吻合,印证了通过年轮损伤组织、生长抑制和释放等参数重建泥石流事件的可行性;Wit指数的变化表明树木年轮的生长释放和抑制滞后于泥石流事件1-3年,并与泥石流规模成正相关。     

四川省山区城镇山洪灾害特征分析

四川省山区城镇山洪灾害分为溪河洪水、泥石流、溪河洪水 泥石流与溪河洪水 泥石流 滑坡四种类型.通过对近50年四川省受山洪灾害危害的典型山区城镇进行调查,从灾害的爆发频率、威胁人口、死亡人口及财产损失四个方面进行相关性分析得出:总体上山洪灾害爆发频率越低,造成的威胁区内人员死亡概率和人均财产损失越大.各类山洪灾害的特征不同:溪河洪水爆发频率高,造成人员伤亡较小,财产损失较大;泥石流的爆发频率低,人员伤亡大,财产损失较大;泥石流 溪河洪水的综合灾害爆发频次低,人员伤亡和财产损失相对较大;泥石流 滑坡 溪河洪水的综合灾害爆发频次最低,威胁人口最多,造成人员伤亡和财产损失都很大.     

“8·3”鲁甸地震小震大灾背景下次生泥石流的易发性分析

2014年8月3日云南鲁甸地震诱发了大量次生地质灾害,研究表明此次地震“小震大灾”的原因是前期干旱导致土体强度降低,在暴雨作用下引发大量次生灾害。在小震大灾的岩土性质基础上,通过分析地形地貌、地质条件、地震活动和极端干湿气候对地质灾害发育的影响,建立地质灾害易发性评价指标,利用 GIS 空间分析技术对震后灾区泥石流易发性进行了快速定量评价。结果显示,地震灾区地质灾害高、中、低易发区面积分别为6865．87 km2、15102．72 km2、9869．06 km2。其中高易发区主要集中于金沙江与牛栏江沿线,呈带状分布,以及受地层岩性的影响呈岛状等不均匀分布,今后在进一步的极端气候影响下,区域泥石流灾害有可能进一步发展。     

Prediction of Debris Flow Runoff Process Based on Hydrological Model: a Case Study at Shenxi Gully,Regarding a Long-Term Impact by Wenchuan Earthquake

Debris flow runoff process is one of key parameters for the design of emergency measures and control engineering. The Shenxi gully in Dujiangyan region,located in the meizoseismal areas of Wenchuan earthquake,was selected as the study area. Based on the research of hazard inducing environment,a soil conservation service( SCS) hydrological model was used to simulate the process of water flow,and then the debris flow runoff process was calculated using the empirical formula combining the results from the SCS hydrological model. Taking the debris flow event occurred on July 9th,2013 as an example,the peak discharges of water flow and debris flow were calculated as 162. 12 and 689. 22 m3/s,with error of 6. 03% compared to the measured values. The debris flow confluence process lasted 1. 8h, which was similar with the actual result. The proposed methodology can be applied to predict the debris flow runoff process in quake-hit areas of the Wenchuan earthquake and is of great importance for debris flow mitigation.     

基于模糊概率方法的泥石流危险性评价

为客观合理评价泥石流危险性,选取泥石流(可能)规模、泥石流发生频率、流域面积、主沟长度、流域最大相对高差、流域切割密度、主沟床弯曲系数、泥砂补给段长度比、24 h最大降雨量、人口密度等10个因子作为泥石流危险性评价指标,运用模糊概率方法建立了泥石流危险性评价模型,并对8条典型泥石流沟的危险性进行了评价.研究表明,模糊概率方法在继承模糊综合评判法的思想和优点的同时,克服了在实际应用中其评价因子权重取值的不确定性,从而为进行有效的泥石流灾害防治提供了可靠的科学依据.     

泥石流启动的临界地表径流深度研究

暴雨过程形成的地表径流导致坡体表面和前缘松散物质向下输移,汇入沟道,演变成危害性较大的泥石流,因此,对于泥石流的启动机理和启动临界条件的研究十分必要.根据下渗曲线法,得出了地表径流深度、入渗率以及降雨强度的关系,并运用牛顿定律、水文学以及土力学等理论,建立了泥石流单颗粒启动、局部启动和整体启动的临界地表径流深度的求解模型,从而可推得临界降雨强度,此可为泥石流的泥石流预警提供了有用的理论基础.     

有限物源流域不同规模的泥石流频率分析--以川西黑水河罗家坝泥石流沟为例

以黑水罗家坝沟1933年、1983年、1984年和1997年泥石流为研究对象,对其流量进行测量和分析计算。从降雨频率与泥石流频率的巨大差异,可知此类泥石流的暴发频率与泥石流的频率差别极大。从历史调查法、地震与土源和产流关系分析法和推理公式与水科院公式的计算模拟推算出罗家坝沟1933年的泥石流远大于百年一遇,1983年的泥石流为百年一遇,1984年的泥石流为50年一遇,1997年泥石流为10年一遇。从一系列的分析计算可知,有限物源流域不同规模的泥石流频率的确定需要考虑多种因素,并进行综合分析。     

中国南方岩溶水化学的某些特征

我国南方碳酸盐岩地区,岩溶水的化学类型和矿化度,从广西经贵州到滇东,在区域上有明显的差异。重碳酸钙型水比例减少,重碳酸钙镁型水呈现递增的趋势。宏观上看,乌江和红水河上游地下水化学径流模数大于下游,各省区平均值,滇东大于贵州又大于广西,即从西向东表现出由大变小的趋势。碳酸盐岩的溶蚀速率也显示这一特点,从而推断:现代岩溶发育强度,总的来看,云贵高原胜过广西地区。