东庄反拱水垫塘防护结构优化与安全性分析

发布时间：2018-06-12 04:18

本文选题：水利工程 + 反拱底板　；参考：《天津大学》2014年硕士论文

【摘要】：针对“高水头、窄河谷、大泄量”的泄洪消能特点,反拱形衬砌式水垫塘利用天然河床基岩形状,将引起水垫塘破坏的水力荷载(主要是上举力与扬压力)传递到两岸山体或拱座,充分发挥出拱结构的超载能力和材料的抗压特性,提高了防护结构的安全性。实践表明,反拱形水垫塘是解决高拱坝泄洪消能问题的有效措施。近年来,国内外许多学者基于理论分析与模型试验,对反拱水垫塘内水动力荷载、衬砌结构的稳定性开展了大量的研究,但是关于反拱水垫塘防护结构优化与安全性研究却涉及不多。本文以泾河东庄水利枢纽坝后水垫塘为研究背景,从工程实际出发,对初拟反拱水垫塘防护结构方案进行多因素的静力非线性优化分析,并将力学模型与数值模型相结合,对反拱水垫塘防护结构进行安全性与稳定性研究,主要成果如下:(1)对反拱防护结构数值分析中的模拟方法进行改进,主要包括材料非线性损伤本构、计入抗剪效应的锚杆单元选取和考虑分缝的流固耦合处理手段等,以使数值模拟研究更为接近实际。(2)在设计扬压力条件下,以稳定性与整体性为主要权衡指标,对反拱水垫塘底板防护结构进行优化研究,确定了反拱半径32m、板块厚度3m、非均匀柔性锚固(边缘板块自由段2.5m,中间板块自由段3m)的方案,达到锚固钢筋与拱座联合承载的目的,承载力较刚性均匀锚固提高30%;粘结滑移效应对常规2m~5m自由段锚固方式的稳定性影响小到可以不计,同样对边坡防护结构进行了优化研究。(3)以有初始间隙的接触单元来模拟拱端裂缝,对反拱底板成拱条件和键槽的成拱作用进行深入研究;计入预应力锚固和不同渗压水平等因素,基于刚体极限平衡法进行拱座抗滑稳定分析,本工程反拱底板承受240kPa扬压力稳定安全有保证;以不耦合的开裂损伤评价方法,研究了不同区域锚固失效时反拱底板的破坏模式。(4)本着“静力设计、动力调整”的原则,对模型实测动水荷载进行处理,结合最大上举力预测公式,得到反拱水垫塘底板和边坡衬砌块的上举力时程,研究优化调整后的反拱水垫塘防护结构在泄流工况下位移、应力等动力响应,并作出安全评价。
[Abstract]:In view of the characteristics of flood discharge and energy dissipation of "high water head, narrow valley, large discharge", the anti-arch lining type water cushion pond uses the natural river bed bedrock shape. The hydraulic load (mainly uplift force and uplift pressure) which caused the damage of water cushion pond is transferred to the mountain body or arch seat on both sides of the bank. The overloading ability of arch structure and the pressure resistance of material are fully brought into play, and the safety of protective structure is improved. The practice shows that the reverse arch water cushion pond is an effective measure to solve the problem of flood discharge and energy dissipation of high arch dam. In recent years, based on theoretical analysis and model tests, many scholars at home and abroad have carried out a great deal of research on hydrodynamic loads and the stability of lining structures in inverted arch ponds. However, there are few researches on the optimization and safety of the protection structure of the reverse arch cushion pond. Taking the backwater cushion pond of Dongzhuang water conservancy project of Jinghe River as the research background, starting from the engineering practice, this paper makes a multi-factor static nonlinear optimization analysis on the preliminary design of the protection scheme of the inverted arch water cushion pond, and combines the mechanical model with the numerical model. In this paper, the safety and stability of the protection structure of the reverse arch cushion pond are studied. The main results are as follows: 1) the simulation method for the numerical analysis of the inverse arch protection structure is improved, which mainly includes the material nonlinear damage constitutive equation. In order to make the numerical simulation more close to the actual conditions, the anchor element with shear effect is selected and the fluid-structure coupling treatment means considering the joint are taken into account so that the stability and integrity are taken as the main tradeoff index under the condition of design uplift pressure. The optimum research on the protection structure of the bottom slab of the reverse arch cushion pond is carried out, and the scheme of inverse arch radius 32 m, plate thickness 3 m and non-uniform flexible anchoring (edge plate free segment 2.5 m, middle plate free section 3 m) is determined to achieve the purpose of joint anchoring of steel bar and arch seat. The bearing capacity is 30% higher than that of rigid uniform anchoring, and the effect of bond-slip effect on the stability of anchoring mode of conventional 2m~5m free section is too small to be taken into account. At the same time, the optimization study of slope protection structure is carried out. (3) the contact element with initial gap is used to simulate the arch end crack, and the arch forming condition of the bottom slab of the reverse arch and the arch forming effect of the keyway are deeply studied. Taking into account the factors of prestressed anchoring and different seepage pressure levels, based on the ultimate equilibrium method of rigid body, the anti-slide stability analysis of arch base is carried out. The safety of anti-slide stability of the reverse arch floor is guaranteed by 240 KPA uplift pressure stability. Based on the principle of "static design, dynamic adjustment", the dynamic load measured by the model is treated and combined with the prediction formula of maximum lifting force. The upward lift time history of the bottom slab and the slope lining block of the reverse arch water cushion pond is obtained. The dynamic responses such as displacement and stress are studied and the safety evaluation is made for the optimized and adjusted protective structure of the reverse arch water cushion pond under the condition of discharge.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV653;TV135

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