【摘要】：雙層堤基廣泛存在于江河中下游地區(qū)，滲透破壞是該類堤基中出險(xiǎn)率最高的破壞形式，多年來針對堤后滲透破壞產(chǎn)生條件的研究已經(jīng)取得了一定的成果，但是對于滲流出口（工程中也稱管涌口）形成后，集中滲流通道（工程中也稱管涌通道）的斷面擴(kuò)展和上溯仍然缺乏深刻的認(rèn)識(shí)，而該通道的發(fā)展直接關(guān)系到滲流出口形成后滲透破壞危險(xiǎn)性的大小，因而本文針對雙層堤基中管涌口產(chǎn)生以后，在強(qiáng)弱透水層之間產(chǎn)生的管涌通道進(jìn)行研究，其發(fā)展包含通道斷面擴(kuò)展和尖端上溯兩個(gè)方面，本文主要針對這兩個(gè)方面開展工作，具體內(nèi)容為： 1.管涌通道發(fā)展的機(jī)理性研究，包含通道擴(kuò)展和上溯兩個(gè)部分。在通道擴(kuò)展方面，以通道邊壁砂顆粒作為研究對象，通過顆粒的穩(wěn)定狀態(tài)來判定通道擴(kuò)展的最終形態(tài)，砂顆粒的穩(wěn)定性由其受力狀態(tài)所決定，在顆粒受力平衡的分析中，引用河流動(dòng)力學(xué)中的相關(guān)概念與公式，考慮了不同粒徑砂顆粒之間的相互作用和起動(dòng)標(biāo)準(zhǔn)，通過計(jì)算得到了作用在砂顆粒上的臨界起動(dòng)速度，考慮通道內(nèi)流速的紊動(dòng)、非均勻分布和通道內(nèi)的水流特性，采用通道斷面平均流速來作為通道擴(kuò)展的判定標(biāo)準(zhǔn)，該標(biāo)準(zhǔn)具有方便測量和簡單易用等特點(diǎn)；在通道上溯方面，提出了以尖端坡降作為通道是否上溯的評判標(biāo)準(zhǔn)，通道上溯后，尖端坡降由于通道各處斷面形狀的變化，其變化趨勢分為穩(wěn)定和增長兩種，如果尖端坡降穩(wěn)定，則通道能夠保持穩(wěn)定，如果尖端坡降增加，則通道無法穩(wěn)定會(huì)持續(xù)上溯，直至貫穿堤基。 2.管涌通道發(fā)展的試驗(yàn)研究，包含通道擴(kuò)展和上溯兩個(gè)部分。在通道擴(kuò)展方面，采用兩種模型尺寸進(jìn)行了多組試驗(yàn)，試驗(yàn)結(jié)果顯示在遠(yuǎn)端和通道內(nèi)水頭差較小時(shí)，滲透力對通道的擴(kuò)展作用較明顯，但是當(dāng)水頭差增大時(shí)，滲透力對通道擴(kuò)展的作用減弱，此時(shí)通道內(nèi)水流沖刷對通道擴(kuò)展的影響則較為明顯；在通道上溯方面，采用兩種覆蓋層模擬方法研究了通道上溯時(shí)平面和剖面的發(fā)展形態(tài)，試驗(yàn)結(jié)果證實(shí)了機(jī)理分析中尖端坡降的相關(guān)內(nèi)容。 3.管涌通道發(fā)展的數(shù)值模擬計(jì)算，包含通道擴(kuò)展和上溯兩個(gè)部分。在通道擴(kuò)展方面，以二維有限元滲流程序?yàn)榛A(chǔ)，以通道斷面平均流速、自然休止角和形狀附加條件三條標(biāo)準(zhǔn)為斷面的擴(kuò)展的判定條件，以遠(yuǎn)端、通道內(nèi)水頭差和通道內(nèi)水流流量為邊界條件，模擬了通道的擴(kuò)展過程，給出了通道的穩(wěn)定狀態(tài)；在通道上溯方面，采用多層透水地層準(zhǔn)三維有限元程序進(jìn)行通道發(fā)展的計(jì)算，兼顧計(jì)算量和計(jì)算精度，提出了一種等效代換方法，在研究通道各處斷面擴(kuò)展判定時(shí)采用通道實(shí)際斷面形式，在三維滲流場計(jì)算時(shí)采用等效矩形斷面形式，等效前后，通道內(nèi)水流和通道外滲流均保持一致，計(jì)算結(jié)果給出了滲流場以及通道尖端坡降，，可用于判定通道上溯的穩(wěn)定性。 4.通過程序計(jì)算結(jié)果與試驗(yàn)結(jié)果進(jìn)行對比，驗(yàn)證了機(jī)理分析與程序編制的正確性，基于程序分析，對典型雙層堤基管涌通道的發(fā)展進(jìn)行了相關(guān)探討。
[Abstract]:The double-layer bank is widely present in the middle and lower reaches of the river, and the seepage and destruction are the most dangerous forms in the bank. The research on the condition of the seepage and destruction of the levee for many years has achieved some results, but after the formation of the seepage outlet (also known as the pipe kick), The cross-section extension and the back-up of the concentrated seepage channel (also known as the pipe surge channel) still lack a deep understanding, and the development of the channel is directly related to the size of the risk of seepage and destruction after the formation of the seepage outlet. The development of the pipe-surge channel between the strong and weak water-permeable layer includes the extension of the channel section and the back-up of the tip. The paper mainly focuses on the two aspects, and the specific content is as follows: 1. The machine rational research of the development of the piping channel Research, including channel extension and back-up In the aspect of channel expansion, as the research object, the channel side wall sand particles are used as the research object, the final shape of the channel expansion is determined by the stable state of the particles, the stability of the sand particles is determined by the stress state, and the analysis of the stress balance of the particles In the paper, the relevant concepts and formulas in the river dynamics are cited, the interaction and start-up criteria between the different grain size sand particles are considered, the critical starting speed on the sand particles is calculated by the calculation, the turbulent flow of the flow velocity in the channel, the non-uniform distribution and the water flow in the channel are taken into account. The average flow rate of the channel section is used as the judgment standard for channel expansion. The standard has the characteristics of convenient measurement and easy to use and the like. When the slope of the tip is stable, the channel can be stable, and if the slope of the tip is increased, the channel can not be stable continuously until the penetrating dike Foundation. 2. Experimental study on the development of piping channels, including channel expansion and back-up In the aspect of channel expansion, two model sizes are used to carry out many groups of tests. The results show that the water head difference in the distal end and the channel is small, the seepage force is more obvious to the expansion of the channel, but when the head difference is increased, the penetration force is used to expand the channel. In this paper, the effect of water flow in the channel on the expansion of the channel is more obvious; in the back of the channel, the development of the plane and the cross section of the channel in the back of the channel is studied by two covering layer simulation methods. The results of the test confirm the phase of the tip slope in the mechanism analysis. off content. 3. Numerical simulation of the development of the piping channel, including the channel expansion and the upper In the aspect of channel expansion, based on the two-dimensional finite element seepage process, three criteria of channel cross-section average flow rate, natural repose angle and shape condition are taken as the extension of the extension of the section, and the head difference in the channel and the flow of water in the channel are measured at the distal end and the channel. For the boundary condition, the expansion process of the channel is simulated, and the stable state of the channel is given. On the back of the channel, the calculation of the channel development is carried out by using the quasi-three-dimensional finite element program of the multi-layer water-permeable stratum, and the calculation quantity and the calculation precision are taken into account. The effect substitution method adopts the form of the actual cross section of the channel at the time of the extension and judgment of the cross section of the research channel, and the equivalent rectangular section form is adopted in the calculation of the three-dimensional seepage field, and the flow in the channel and the outside seepage of the channel are consistent before and after the equivalent, and the calculation result shows the seepage field and the through-flow field. The slope of the channel tip can be used to determine if the channel is on the channel On the basis of the program analysis, the development of typical double-layer bank-based piping is verified by comparing the results of the program with the results of the test.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TV871;TV223.4

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