云南省寻甸县沙湾大沟泥石流地质特征与危险性评价

发布时间：2018-08-03 10:34

【摘要】：沙湾大沟泥石流地处云南省寻甸县金源乡境内,位于区域活动带小江断裂带附近,小江断裂带西支断裂东侧。该泥石流是一种泥沙、石块、水气相互混合而成的洪流且常见于山区的地质灾害之一。具有复杂性、偶然性、规律性、必然性等特点。泥石流的危险性及危害性也称之为危险度和危害度。危险度是指受损对象遭受泥石流损害的可能性大小：危害度是指泥石流对流域内被危害对象的损害程度。危险度是泥石流本身所具有的,而危害度则与被危害对象在流域内的位置和强度有关。对泥石流进行危险性评价是研究和防治泥石流的一个重要途径。层次分析法是一种数量化理论的多元统计分析方法。结合该泥石流的实际情况,本次研究分成目标层、准则层和指标层三个层次,目标层为泥石流危险度评价；准则层包括成灾因素、地形地貌、物源条件等内容；指标层包括松散物质储量、主沟平均比降、总流域面积、地形坡度、年24小时最大降雨量、最大相对高差、泥沙补给段长度比、主沟道长度、流域切割密度、主沟床弯曲系数、植被覆盖率等因子。通过前期基础工作的调查和计算,对指标层中各因子进行赋值及评分,并将所有因子评分进行加和,最终利用所得“和”对沙湾大沟泥石流危险性评价。沙湾大沟泥石流流域地质构造复杂,地层岩性复杂、破碎,地形地貌条件复杂,降雨丰沛且雨季活动性较强。该泥石流沟位于活动性断层小江断裂带之嵩明-苍溪大断层东侧约1.5km处,受活动性断层的影响和作用,研究区内岩体结构破碎,地形起伏变化较大。沙湾大沟呈“葫芦”状,上游地形平缓宽阔,沟道多呈“V”形,出露地层岩性为灰岩、白云质灰岩、泥质粉砂岩、页岩等碳酸盐岩和碎屑岩,沟岸较不稳定,多处分布有滑坡和崩塌等不良地质,为泥石流的形成提供了有利的物源条件,为泥石流的形成区；中游地形切割较深,地形较陡,沟道较窄,出露地层岩性为白云质灰岩、玄武岩等坚硬岩组,沟岸及沟床较稳定,有利于泥石流流体快速流通,为泥石流的流通区；下游地形平坦开阔,出沟口呈扇形状,堆积层较厚,沟床宽大且切割浅,泥石流流体流速急剧下降,常常于此堵塞停积,为泥石流的堆积区。通过调查分析研究和参数计算,本次论文研究主要成果和认识有以下几点：(1)沙湾大沟泥石流流域形态具有形成区、流通区、堆积区的分区段个特征,为泥石流的形成奠定基础条件和提供空间场所。(2)研究区内地层出露不完全,岩性以泥质粉砂岩、页岩等碎屑岩为主,受活动性断层的影响和破坏,岩体破碎、风化严重,节理裂隙发育,有利于物源条件的形成。(3)泥石流重要参数计算结果,容重γc=2.12t/m3,流速uc=5.05m/s,流量Qz=61.5m3/s,整体冲击力F=94.42K.Pa,单块巨石冲击力F=1600.00KPa。(4)沙湾大沟泥石流形成机制正是在物源条件、水源条件、地形条件三者有机结合的充要条件下爆发的,具有爆发规模大、频次高、流速大、冲击力大,并携带巨大的粗颗粒等运动及动力特征。(5)运用层次分析法进行泥石流危险评价结果Q=136。(6)沙湾大沟泥石流下游分布有集镇、村庄、道路交通、电力通讯和农田水利等基础设施,现状危害程度大。泥石流以掩埋(淤埋)、冲击(撞击)、冲刷与磨蚀、堵塞和挤压河道等形式对其危害对象将造成不同程度的损毁,即泥石流危害机理。(7)沙湾大沟泥石流从物源条件、水源条件、地形条件等三方面来看,其发展趋势不论是规模还是频率均将会有所增加。(8)沙湾大沟泥石流是一条沟谷型粘性高频极严重危险性泥石流。
[Abstract]:Shawan ditu debris flow is located in Jin Yuan Township, Xundian County, Yunnan Province, located in the vicinity of the Xiaojiang Fault Zone and the east side of the West Branch fault of the Xiaojiang Fault Zone. The debris flow is a kind of sediment, stone, water and gas mixed with each other and one of the geological disasters in the mountain area. It is complicated, accidental, regular and inevitable. The risk and harmfulness of debris flow is also known as the degree of danger and hazard. The degree of danger refers to the possibility of the damage of the damaged object by debris flow: the degree of damage is the degree of damage to the damaged object in the basin. The degree of the risk is the debris flow itself, and the degree of danger is in the position of the damaged object in the basin. The risk assessment of debris flow is an important way to study and prevent debris flow. The analytic hierarchy process is a multivariate statistical analysis method of quantitative theory. Combined with the actual situation of the debris flow, this study is divided into three levels, target layer, standard layer and index layer, and target layer is the evaluation of debris flow hazard degree. The standard layer includes disaster factors, terrain and geomorphology, source conditions and so on. The index layer includes the loose material reserves, the average ratio drop of the main ditch, the total basin area, the terrain slope, the maximum rainfall of 24 hours, the maximum relative height difference, the length ratio of the sediment supply section, the main channel length, the watershed cutting density, the main groove bed bending coefficient, vegetation coverage and so on. Factor. Through the investigation and calculation of the previous basic work, the factors in the index layer are assigned and scored, and all the factors are added and added. Finally, the risk assessment of the debris flow in the Shawan big gully is finally used. The geological structure of the Shai Wan ditu mudflow basin is complex, the lithology is complex, and the topography and geomorphology conditions are complex. The debris flow gully is located at the east side of the Songming Cangxi large fault of the active fault Xiaojiang Fault Zone, about 1.5km, which is affected and affected by the active fault. The rock mass structure in the study area is broken and the terrain fluctuates greatly. The Shawan big gully appears "gourd", the upstream terrain is gentle and broad, the channel is mostly "V". The lithology of form and outcropping strata is limestone, dolomitic limestone, muddy siltstone, shale and other carbonate and clastic rocks. The gully bank is not stable, and there are many bad geological conditions, such as landslides and collapses, which provide favorable source conditions for debris flow formation, the formation of debris flow, the deep cutting of the terrain, the narrow terrain and the narrow channel. The stratum lithology is dolomitic limestone, basalt and other hard rock groups, and the gully bank and trench bed are more stable. It is beneficial to the rapid circulation of debris flow and the circulation area of debris flow. The downstream terrain is flat and open, the outlet is fan shape, the accumulation layer is thicker, the groove bed is wide and the flow velocity of debris flow drops sharply, often the mud is stopped and mud is accumulated. Through investigation and analysis and parameter calculation, the main achievements and understanding of this paper are as follows: (1) the morphology of the debris flow in the Shawan ditu mudflow basin has the characteristics of the formation area, the circulation area and the accumulation area, which lays the foundation for the formation of debris flow and provides the space for the debris flow. (2) the outflow of the inland layer in the study area Not completely, lithology is dominated by muddy siltstone, shale and other clastic rocks, affected and destroyed by active faults, rock mass broken, weathering, joint fracture development, and formation of source conditions. (3) calculation results of important parameters of debris flow, bulk weight gamma c=2.12t/m3, flow velocity uc=5.05m/s, flow Qz=61.5m3/s, overall impact force F=94.42K.Pa, single block The formation mechanism of the debris flow in F=1600.00KPa. (4) Shawan big gully is just under the condition of physical source, water source and topographic conditions with the organic combination of three organic combination. It has large scale, high frequency, high velocity, great impact force, and carrying huge coarse grain. (5) using analytic hierarchy process to carry out mud The result of the rock flow hazard assessment Q=136. (6) the downstream of the Shawan ditu debris flow is distributed in towns, villages, road traffic, electric power communication and farmland water conservancy. The current situation is very harmful. The debris flow is buried (buried), impact (impact), erosion and abrasion, clogging and extrusion of river channels will cause damage to different extent, The damage mechanism of debris flow. (7) the development trend of debris flow in Shawan ditu debris flow, from three aspects of source condition, water source condition and terrain condition, will increase in both scale and frequency. (8) the debris flow of Shawan big gully is a valleys viscous high frequency extremely dangerous debris flow.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.23

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