均质土堤漫溢溃决过程试验研究及数值模拟技术
发布时间：2018-10-08 12:49
【摘要】：堤防是最常用的工程防洪措施之一。堤防通常修筑在河道或其它水体的外围,束缚水流,防止洪水漫溢,其中土堤由于造价低,便于就地取材,应用最为广泛。然而堤防工程要做到绝对安全几乎是不可能的,不合理的设计、建造技术和材料,复杂的基础条件,超标准的洪水,人为或动植物的破坏,都有可能导致工程措施的失效。因此堤防溃决既是洪水灾害发生的结果,也是引发洪水灾害的一个原因。土堤的漫溢溃决是一种最为常见的堤防溃决形式。开展堤防溃决过程及其影响因素等领域的研究,对于合理地确定堤防的防洪设计标准、评估溃堤洪水淹没损失、制定应急规划方案、认识溃口发展规律和口门区冲淤变化规律都具有十分重要的意义,并为制定溃口的快速堵复方案提供科学的依据。 溃堤具有突发性和危险性,现场监测困难,现有实测资料较少,物理模型和数值模拟成为重要的研究手段。本文在前人研究成果的基础上,结合理论分析,运用概化物理模型试验和数值模拟的方法,对非粘性和粘性均质土堤漫溢溃决过程、溃决区域水沙运动变化及溃决洪水演进规律进行研究。主要内容如下： (1)在弯道水槽中开展系列非粘性土堤防漫溢溃决试验,考虑了上游河道流量、不同初始河道水位、不同筑堤材料等情况,研究溃口的垂向侵蚀、横向展宽过程、溃口附近水流结构特点以及内外江水位变化过程,分析其过程特点及影响因素。 (2)进一步开展粘性土堤漫溢溃决系列试验。试验监测粘性土堤防漫溢溃决的溃口发展过程、内江水位变化过程以及溃口前的流速变化过程。通过实测资料总结了粘性土堤溃口的陡坎溯源冲刷形式、溃口横向展宽的形式以及最终的溃口形态,分析上游来流量、堤防土体的含水率以及孔隙率等因素对溃口发展以及最终形态的影响。分析堤防溃决后内江水位以及溃口前流速的变化过程及其与溃口发展的对应关系。 (3)建立了堤防漫溢溃决平面二维水流数学模型,采用Roe近似解算子方法求解水流数值通量,界面两侧守恒变量的重构利用MUSCL-TVD格式,时间离散采用具有二阶时间精度的预测和校正两步格式,该方法可准确模拟间断水流。 在此基础上建立以推移质泥沙运动为主的非粘性土堤防漫溢溃决平面二维水沙数学模型。模型的基本方程通过严格守恒的水、沙两相流动基本方程组推导而来,得到能反映河床变形项对水流运动影响的基本方程。泥沙对流通量的求解采用一阶迎风格式。通过水下部分侵蚀-水上部分坍塌模式计算溃口展宽过程。数学模型经经典算例和水槽试验结果验证。 (4)概化物理模型试验结合数学模型计算分析,研究了不同河道水流条件以及筑堤材料特性下的溃口区域水位及溃决流量变化过程。相同的河道水流条件及筑堤材料情况下,溃决流量的大小还与初始诱导溃口的宽度、溃口垂向以及横向发展情况、堤防高度等有关。 (5)比较了非粘性土堤防和粘性土堤防漫溢溃决在溃口发展过程、溃决区域水位流量过程变化及其影响因素等方面的区别。如：由于筑堤土体特性不同导致的水土耦合作用方式不同,非粘性土堤防溃口垂向主要以冲刷沟形式发展,粘性土堤防溃口垂向以陡坎的溯源冲刷自坡脚向坡顶；非粘性土堤防溃口展宽伴随垂向冲深,而粘性土堤防溃口展宽在垂向冲深发展完成以后才开始出现；粘性土堤防溃决速度要远小于非粘性土堤防。以上溃口发展过程的特点影响了溃决流量过程。非粘性土堤防溃决流量在溃口发展的初始阶段即迅速增大,达最大值后逐渐减小；粘性土堤防溃决流量在垂向冲深发展完成后后才开始突然增加。
[Abstract]:Dikes are one of the most common engineering measures. The dike is usually built on the periphery of river course or other water body to restrain water flow and prevent flood overflow. However, the absolute safety of embankment works is almost impossible, unreasonable design, construction technology and material, complex foundation conditions, ultra-standard flood, man-made or plant and plant destruction, all of which can lead to failure of engineering measures. Therefore, dike burst is not only the result of flood disaster, but also a cause of flood disaster. The overflow of embankment is one of the most common forms of embankment collapse. The study of embankment break-up process and its influencing factors is very important to reasonably determine the flood control design standard of dikes, to evaluate the flood loss of collapse flood, to set up the plan for emergency planning, to understand the law of break-up development and the law of erosion and siltation in the gate area. and provides scientific basis for establishing a rapid block-breaking complex scheme of the break-out. The dike burst has the characteristics of bursty and dangerous, the site monitoring is difficult, the existing measured data is less, the physical model and the numerical simulation become important research. In this paper, based on the previous research results, combined with the theoretical analysis, the generalized physical model test and numerical simulation method are used to study the flood-overflow process of non-adhesive and viscous homogeneous earth dikes, the movement variation of the collapse area and the law of the evolution of burst flood. Study. Main Content The following conclusions are as follows: (1) In the curve water tank, a series of non-cohesive soil embankment overflow test is carried out, considering the upstream channel flow, different initial river water level, different embankment materials, etc., and the vertical erosion and transverse erosion of the collapse are studied. The process characteristics of water flow structure near the break-up process and the change of water position inside and outside are analyzed and the process characteristics are analyzed. and influencing factors. (2) further developing cohesive soil embankment A series of tests and tests to monitor the collapse of overflow of clayey embankment, the process of water level change in Neijiang and the collapse According to the measured data, the source tracing form of steep ridge, the form of transverse widening of collapse port, and the final fracture morphology are summarized. The flow of upstream, the water content of embankment and porosity are analyzed. The changes of the water level of the inner river and the flow velocity before the collapse and the collapse of the dike are analyzed in this paper. In this paper, a mathematical model of two-dimensional water flow is established, which uses Roe approximate solution operator method to solve the numerical flux of water flow. The reconstruction of conservation variable on both sides of the interface utilizes MUSCL-TVD scheme, and the time dispersion adopts the second order time precision. the prediction and correction of the degree is in a two-step format, The discontinuous water flow can be simulated accurately. On the basis of this, a non-cohesive soil embankment dominated by bed mud sand movement is established. The basic equation of the model is derived by the strict conservation of the basic equations of the flow of water and sand, which can reflect the change of the river bed. The basic equation of the influence of the shape term on the movement of water. The solution of the flux is in the windward format. Erosion over the water-water A Mathematical Model for the Calculation of the Break-up Process in Partial Stroke Mode It is verified by the classical calculation example and the experimental results of the water tank. (4) The calculation and analysis of the mathematical model of almost all physical model tests are carried out, and the water flow conditions of different river courses and the characteristics of embankment materials are studied. In the same river flow conditions and embankment materials, the size of the collapse flow is also related to the width and collapse of the initial induced collapse. It is related to the development of embankment, the height of embankment, etc. (5) Compared with the non-cohesive soil dikes and clayey soil dikes, the collapse of embankment is in the process of burst development and the collapse area. The difference between the change of water level flow process and its influencing factors, such as the different modes of soil and water coupling caused by different soil characteristics of embankment, is mainly developed in the form of scour ditch. To the top of the slope, the collapse broadening of the non-cohesive soil embankment is accompanied by the vertical drawing depth, and the collapse broadening of the clay embankment starts to occur after the vertical drawing and deep development is completed. and the collapse speed of the cohesive soil embankment is far smaller than that of the non-cohesive soil embankment. The characteristics of the above-mentioned break-up development process affect the process of burst flow. The collapse flow rate of non-cohesive soil embankment increases rapidly at the initial stage of the collapse development, and decreases gradually after the maximum value reaches the maximum value.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV871
[Abstract]:Dikes are one of the most common engineering measures. The dike is usually built on the periphery of river course or other water body to restrain water flow and prevent flood overflow. However, the absolute safety of embankment works is almost impossible, unreasonable design, construction technology and material, complex foundation conditions, ultra-standard flood, man-made or plant and plant destruction, all of which can lead to failure of engineering measures. Therefore, dike burst is not only the result of flood disaster, but also a cause of flood disaster. The overflow of embankment is one of the most common forms of embankment collapse. The study of embankment break-up process and its influencing factors is very important to reasonably determine the flood control design standard of dikes, to evaluate the flood loss of collapse flood, to set up the plan for emergency planning, to understand the law of break-up development and the law of erosion and siltation in the gate area. and provides scientific basis for establishing a rapid block-breaking complex scheme of the break-out. The dike burst has the characteristics of bursty and dangerous, the site monitoring is difficult, the existing measured data is less, the physical model and the numerical simulation become important research. In this paper, based on the previous research results, combined with the theoretical analysis, the generalized physical model test and numerical simulation method are used to study the flood-overflow process of non-adhesive and viscous homogeneous earth dikes, the movement variation of the collapse area and the law of the evolution of burst flood. Study. Main Content The following conclusions are as follows: (1) In the curve water tank, a series of non-cohesive soil embankment overflow test is carried out, considering the upstream channel flow, different initial river water level, different embankment materials, etc., and the vertical erosion and transverse erosion of the collapse are studied. The process characteristics of water flow structure near the break-up process and the change of water position inside and outside are analyzed and the process characteristics are analyzed. and influencing factors. (2) further developing cohesive soil embankment A series of tests and tests to monitor the collapse of overflow of clayey embankment, the process of water level change in Neijiang and the collapse According to the measured data, the source tracing form of steep ridge, the form of transverse widening of collapse port, and the final fracture morphology are summarized. The flow of upstream, the water content of embankment and porosity are analyzed. The changes of the water level of the inner river and the flow velocity before the collapse and the collapse of the dike are analyzed in this paper. In this paper, a mathematical model of two-dimensional water flow is established, which uses Roe approximate solution operator method to solve the numerical flux of water flow. The reconstruction of conservation variable on both sides of the interface utilizes MUSCL-TVD scheme, and the time dispersion adopts the second order time precision. the prediction and correction of the degree is in a two-step format, The discontinuous water flow can be simulated accurately. On the basis of this, a non-cohesive soil embankment dominated by bed mud sand movement is established. The basic equation of the model is derived by the strict conservation of the basic equations of the flow of water and sand, which can reflect the change of the river bed. The basic equation of the influence of the shape term on the movement of water. The solution of the flux is in the windward format. Erosion over the water-water A Mathematical Model for the Calculation of the Break-up Process in Partial Stroke Mode It is verified by the classical calculation example and the experimental results of the water tank. (4) The calculation and analysis of the mathematical model of almost all physical model tests are carried out, and the water flow conditions of different river courses and the characteristics of embankment materials are studied. In the same river flow conditions and embankment materials, the size of the collapse flow is also related to the width and collapse of the initial induced collapse. It is related to the development of embankment, the height of embankment, etc. (5) Compared with the non-cohesive soil dikes and clayey soil dikes, the collapse of embankment is in the process of burst development and the collapse area. The difference between the change of water level flow process and its influencing factors, such as the different modes of soil and water coupling caused by different soil characteristics of embankment, is mainly developed in the form of scour ditch. To the top of the slope, the collapse broadening of the non-cohesive soil embankment is accompanied by the vertical drawing depth, and the collapse broadening of the clay embankment starts to occur after the vertical drawing and deep development is completed. and the collapse speed of the cohesive soil embankment is far smaller than that of the non-cohesive soil embankment. The characteristics of the above-mentioned break-up development process affect the process of burst flow. The collapse flow rate of non-cohesive soil embankment increases rapidly at the initial stage of the collapse development, and decreases gradually after the maximum value reaches the maximum value.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV871
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