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涌浪条件下冰湖溃坝的模拟实验研究
Alternative TitleLaboratory test of the mechanics on Glacier lake outburst caused by waves
Language中文
刘建康
Thesis Advisor程尊兰
2013
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword涌浪 冰湖溃决 模拟实验 溃坝机制 溃决峰值流量
Abstract通过室内模拟实验,论文主要探讨了冰湖涌浪溢流溃坝类型的发展过程与溃决流量特征,分析了涌浪条件、湖区特征和坝体特征对溃坝形成机制的影响,对比研究了涌浪溢流溃坝与普通溢流溃坝模型形成机制的差异,建立了基于影响因子的峰值流量计算预测公式,得出以下结论: (1)有别于普通溢流溃坝,涌浪条件是冰湖涌浪溢流溃坝类型的核心因素,是溃口形成的直接原因。涌浪条件是否充分,影响溃口雏形的形成和溃口发展的速率,从而导致不同涌浪条件下的溃决流量特征各存差异。 (2)表征库容的湖区长度与湖区水深对溃坝形成过程的影响机制不同:同等条件下,不同湖区长度的库容与溃口发展速率呈反比,不同湖区水深的库容与溃口发展速率呈正比,故两个特征参数与溃决产生的峰值流量之间的响应关系各存差异:湖区长度对峰值流量的影响程度低于湖区水深。 (3)坝体组成通过影响含水率变化和基质吸力强弱构建不同等级的抗冲刷能力,其中坝体组成越均匀,坝体抗冲刷能力越强,反之抗冲刷能力越弱;坝体鞍部横断面面积则通过影响溃口形成和发展过程中侵蚀方量的不同,导致溃决过程的差异,其中坝体鞍部横截面面积越大,坝体抗冲刷能力越强,反之抗冲刷能力越弱。 (4)当涌浪条件充分时,冰湖涌浪溢流溃坝类型的发展过程相对普通溢流溃坝来讲,具有发展迅速和尖瘦峰形流量过程的特点;当涌浪条件不充分时,涌浪溢流溃坝的发展过程相对普通溢流溃坝来讲,具有发展缓慢、峰值流量偏小和平缓峰形流量过程的特点。 (5)通过实验对对涌浪溢流溃坝的各特征参数进行了分析,确定影响溃决峰值流量的主要因子,分别是:表征涌浪条件的初始涌浪波幅,湖区水深,湖区长度、坝体鞍部横截面面积和坝体组成的挑选系数。通过量纲分析和回归分析得到涌浪溢流溃坝的无量纲峰值流量预测公式: Q_m^*=583A_0^0.244 〖L_d^(-0.244) H〗_0^1.307 L^0.538 E^(-0.923) C_u^0.592 (6)通过实验数据的分析,初步建立了涌浪溢流溃坝的临界条件判别式,并确定发生溃决的临界阈值为0.1。 I_b^*=1.78A_0^0.665 〖L_d^(-0.665) H〗_0^2.229 E^(-1.115) C_u^0.658 (7)通过藏东南帕隆藏布流域光谢错溃决案例的检验,预测公式和临界判别式接近实测值;应用于莫如弄巴流域的错下湖溃决危险评估,认为预测公式和溃决临界条件的判别式计算结果具有一定的参考价值。
Other AbstractUnder laboratory conditions, this paper mainly focused on: the development and characteristics of dam failure caused by waves; influence of wave conditions, lake and dam features on the mechanism of dam break; difference of the mechanism of dam failure caused by waves and overtopping; a formula to predict peak discharge based on the influenced factors. Conclusions as followed: (1) Different from dam failure caused by overtopping, wave condition is the Key influenced factor which does most impact on the mechanism of dam failure. The wave condition is sufficient or not, it influences the rate of breach formation and development, which induce different characteristics of outflow under different wave conditions. (2) Lake features are main factors which influence the erosion capacity of outflow, but the lake length and the lake depth, which decide the lake volume, make different influences on the mechanism of dam failure: the lake length is inversely proportional to the development of dam failure, but the lake length is proportional to the development of dam failure. Therefore, relationship between this two lake- feature parameters and the peak discharge of outflow are different, which is that the length of lake is less influence on the peak discharge of outflow than the depth. (3) Dam features are main factors which influence the anti-erosion ability of dam. Different dam composed make difference in moisture content and matric suction, which build different anti-erosion ability: the smaller particle size and more uniform build stronger anti-erosion ability, and vice versa; Different cross-section of dam induces different amount for the erosion in the breach formation and development: the greater cross-section of dam builds stronger anti-erosion ability, and vice versa. (4) When wave condition is sufficient, compared to dam failure caused by overtopping, dam failure caused by waves is a relatively rapid development with sharp shape of outflow process. When wave condition is insufficient, compared to dam failure caused by overtopping, dam failure caused by waves is a relatively slow development and a smaller peak discharge with gentle shape of outflow process. (5) Influence of characteristic parameters on the mechanism of dam failure is analyzed and 5 main factors which affect the peak discharge are determined, including the initial wave amplitude, lake depth, lake length, cross-section and coefficient of uniformity of the dam. By the analysis of dimensionless and regression, a formula to predict the peak discharge of outflow is obtained as followed: Q_m^*=583A_0^0.244 〖L_d^(-0.244) H〗_0^1.307 L^0.538 E^(-0.923) C_u^0.592 (6) By the analysis of the influence of characteristic parameters on the mechanism of dam failure, a formula to predict the threthold of dambreak is obtained as followed, and the value of threthold is ablout 0.1: I_b^*=1.78A_0^0.665 〖L_d^(-0.665) H〗_0^2.229 E^(-1.115) C_u^0.658 (7) Tested by the GLOF case of Guangxiecuo occurred in 1988, Tibet, it is acceptable to find that the predicted result computed by the above formula is closer to the measured value. Applied to the potential GLOF of Cuoxiahu nearby, the predicted result computed by the above formula makes sense to a certain extent
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7045
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
刘建康. 涌浪条件下冰湖溃坝的模拟实验研究[D]. 北京. 中国科学院研究生院,2013.
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