【作者】 刘孝俊；

【导师】 李永刚；

【作者基本信息】 太原理工大学 ， 水工结构工程， 2012， 硕士

【摘要】 随着国民经济的快速发展,基础设施及一些大型重点工程如南水北调中线工程、山西大水网等建设项目进行地如火如荼,这些工程往往需要穿山越岭,这就使得涵洞这种造价相对低廉的地下建筑物越来越多的出现在工程建设中。然而,涵洞埋设位置隐蔽,一旦出现问题不容易及时发现和检修,容易造成严重事故,因此这些工程设计和施工的重要性不言而喻。而目前,涵洞的土压力计算理论尚不成熟,公式繁多但没有统一的理论,甚至于各个规范里的算法、标准及适用范围都不尽相同。由此造成计算结果相差较大,或偏于保守造成资源的浪费,或偏不安全造成事故隐患。所以,继续深入研究涵洞土压力的理论具有较强的现实意义。本文在文献所述试验的基础上,采用ANSYS软件进行数值模拟,分析了刚性地基下沟埋式涵洞垂直土压力在沟槽宽度及边坡等因素影响下的分布规律,并得到了垂直土压力系数变化情况,所得结果与室内模型试验的结果吻合良好。在此基础上,通过建立数值模型,进一步探究了刚性地基下填土性质不同及柔性地基下地基弹模比不同对侧向土压力的影响及侧向土压力系数的变化情况,并得出了填土等沉面与侧向土压力之间的关系,同时得到了涵洞侧向土压力的分布形状变化规律。结果表明：在刚性地基条件下,随着填土高度的增加,涵洞侧向土压力的分布形状逐渐由梯形向倒梯形变化；当H/D一定,E0越大,填土等沉面高度越小,涵洞侧向土压力越大；当E0一定,H/D越大,等沉面高度越小,涵洞侧向土压力越大；涵洞侧向土压力系数随着填土高度的增加先增大后趋于定值；当填土变形模量超过30MPa时,填土变形摸量的改变对涵洞侧向土压力及侧向土压力系数影响较小。在柔性地基条件下,当地基弹模比小于50时,涵洞侧向土压力为梯形分布；当地基弹模比大于50时,分布形状逐渐变为矩形；当地基弹模比大于100后,分布形状变化极小；当H/D一定,地基弹模比越大,等沉面高度越大,涵洞的侧向土压力越小；当地基弹模比一定,H/D越小,等沉面高度越大,涵洞的侧向土压力越小。与刚性地基情况不同的是,侧向土压力系数随着填土高度的增加先不断减小后趋于稳定值。本文主要是采用有限元法模拟、分析填土性质及地基弹模比对上埋式涵洞侧向土压力的影响,对进一步完善涵洞计算理论具有重要意义,论文得出了一些可指导工程设计和施工的结论和建议,但仍需实际工程的检验。更多还原

【Abstract】 With the rapid development of national economy, infrastructure and the key projects, such as the Middle Route in the South-to-North Water Transfer Project and Shanxi large-scale water conservancy network which require crossing mountains are increasing vigorously. This makes culvert of underground structures which has a low cost relatively appear more and more in construction projects. However, the buried position of culvert is concealed, it’s difficult to detect and overhaul timely which will result in disastrous accidents. Therefore, the importance of design and construction of these projects is self-evident. At present, the culvert theory of earth pressure is still not mature, the formulas are numerous and there is no unified theory, and even the algorithm, standards and scope of application in various specifications are different. Hence it causes the results have great difference, either conservative which results in waste of resources or unsafe which causes hidden trouble. Therefore, further study of earth pressure theory of culvert has a strong practical significance.Based on the experiment described in the literature [47][48], ANSYS was used to simulate and analyze the vertical soil pressure distribution of ditch culvert in rigid foundation under the influence of the trench width and slope factors in this paper. Also, the vertical earth pressure coefficient changes were obtained, the results are in good agreement with the results of model experiment. On this basis, the influence on lateral earth pressure of different nature of filling in the rigid foundation and the different ratio of foundation elastic modulus in the flexible foundation were explored further and the variation of lateral earth pressure coefficient was obtained by the establishment of numerical model. The relationship between plane of equal settlement and lateral earth pressure of positive-buried culvert and change regularity of distribution shape of lateral earth pressure were also obtained. The results show that:under the condition of rigid foundation, with the increase of filling height, the distribution shape of lateral earth pressure changes from trapezoid to the inverted trapezoid gradually, When H/D is constant, the greater the Eo, the lower the plane of equal settlement, the greater the lateral earth pressure; When Eo is constant, the greater H/D, the lower the plane of equal settlement, the greater the lateral earth pressure; Lateral earth pressure coefficient increases firstly and then tends to a fixed value with the increase of filling height; The impact of Eo which is more than30MPa on lateral earth pressure and coefficient of lateral earth pressure is less. Under the conditions of the flexible foundation, when the ratio of foundation elastic modulus is less than50, the distribution shape of lateral earth pressure is trapezoidal; When the ratio of foundation elastic modulus is more than50, the distribution shape of lateral earth pressure becomes rectangular gradually; When the ratio of foundation elastic modulus is more than100, the distribution shape changes little; When H/D is constant, the greater the ratio of foundation elastic modulus, the higher the plane of equal settlement, the smaller the lateral earth pressure; When the ratio of foundation elastic modulus is constant, the smaller the H/D, the higher the plane of equal settlement, the smaller the lateral earth pressure. Lateral earth pressure coefficient decrease firstly and then tends to a fixed value with the increases of filling height under the flexibility foundation, which is different with rigid foundation.In this paper, the finite element method is mainly used to simulate and analyze the impact of the backfill nature and the ratio of foundation elastic modulus on the lateral earth pressure of Culverts, which has great significance for improving the Computation Theory of culvert further, some conclusions and recommendations that can guide design and construction are obtained also, but this still requires test of actual project.更多还原