考虑挡土墙位移模式和位移大小的主动土压力研究
发布时间：2018-11-26 09:59
【摘要】：研究挡土墙上土压力的问题一直备受人们的关注。目前,普遍用来计算土压力的理论当属库仑土压力理论和朗肯土压力理论,但是这两种理论都是在一定的假设前提下使用的,应用到工程实际中时计算的结果难免会产生误差。首先库仑理论认为挡土墙在工作时为均匀平移的状态是不合实际的,因为在实际施工过程中,挡土墙的位移模式可以有很多种;其二,该理论认为墙后土体达到极限平衡状态时,利用在静力平衡条件下列平衡方程,最终计算出土压力大小也是不准确的,因为在现实情况下,土体并不能真正意义上达到极限状态,所以利用该方法计算出的土压力往往比实际值小些;第三,库仑理论的计算通常将墙后土体看作一个整体,那么也就忽略了实际情况下土体自身的应力变化情况,计算的结果也不准确。然而,朗肯理论虽然对库仑理论做了改进,考虑了土体自身的应力变化情况,但是却忽略了挡土墙与填土接触面之间的摩擦阻力,因而也是不准确的。因此,为了加强现实情况下,挡土墙设计的合理性,需要切实的考虑影响挡土墙土压力变化的各种因素。本文针对挡土墙位移模式以及位移大小的变化对主动土压力的影响,在诸多学者研究的基础上,提出了一种改进的计算理论。本文以刚性挡土墙为例,认为其在实际施工中可能会发生三种位移模式:绕墙底转动(RB模式)、绕墙顶转动(RT模式)和平动(T模式),并定义挡土墙从初始静止状态移动到极限主动状态时会存在一个“中间过渡状态”,称之为非极限主动状态。认为挡土墙背离土体移动的过程中,随着墙体位移的增大,填土摩擦角也逐渐发挥出来,引入摩擦角发挥值的概念,建立摩擦角与位移之间的关系;同时墙背所受主动土压力值也因为位移的增加而从静止土压力状态逐渐减小,慢慢趋向于极限主动土压力值,此时就可利用摩擦角与位移之间的关系,求解出土体处在非极限主动状态下的主动土压力值。最终可以得到刚性挡土墙在不同位移模式、不同位移大小时,其在非极限状态下的主动土压力大小、分布以及合力作用点的位置等情况,并把本文方法求得的结果与已有计算理论及试验论证结果进行对比,得出利用本文方法来计算出的主动土压力值更精确,在挡土墙的设计使用中将更合理、更科学。
[Abstract]:The study of earth pressure on retaining wall has been paid more and more attention. At present, Coulomb earth pressure theory and Rankine earth pressure theory are commonly used to calculate earth pressure. However, these two theories are both used under certain assumptions, and the calculation results will inevitably produce errors when applied to engineering practice. First of all, Coulomb theory holds that the state of uniform translation of retaining wall is not practical, because in the actual construction process, there can be many kinds of displacement modes of retaining wall. Second, the theory holds that when the soil behind the wall reaches the ultimate equilibrium state, it is also inaccurate to calculate the earth pressure finally by using the following equilibrium equations under the static equilibrium condition, because in reality, The soil can not reach the limit state in real sense, so the earth pressure calculated by this method is usually smaller than the actual value. Thirdly, the Coulomb theory usually regards the soil behind the wall as a whole, so the stress variation of the soil itself is ignored, and the calculation results are not accurate. However, although Rankine's theory improves Coulomb's theory and takes into account the stress variation of the soil itself, it ignores the friction resistance between the retaining wall and the filling interface, so it is also inaccurate. Therefore, in order to strengthen the rationality of the design of retaining wall, it is necessary to consider the factors that affect the change of earth pressure. In view of the influence of displacement mode and displacement on active earth pressure of retaining wall, an improved calculation theory is put forward on the basis of many scholars' research. Taking rigid retaining wall as an example, it is considered that three kinds of displacement modes may occur in actual construction: rotation around the bottom of the wall (RB mode), rotation around the top of the wall (RT mode) and peaceful movement (T mode). It is also defined that there will be a "intermediate transition state" when retaining wall moves from the initial static state to the ultimate active state, which is called the non-limit active state. It is considered that with the increase of wall displacement, the friction angle of fill soil is gradually developed in the process of moving away from the soil. The concept of exertion value of friction angle is introduced, and the relationship between friction angle and displacement is established. At the same time, the active earth pressure on the back of the wall decreases gradually from the static earth pressure to the limit active earth pressure because of the increase of displacement, and the relationship between friction angle and displacement can be utilized. The value of active earth pressure in non-limit active state of soil is calculated. Finally, the active earth pressure, the distribution of active earth pressure and the position of working point of the rigid retaining wall in non-limit state can be obtained under different displacement modes and different displacements. The results obtained by this method are compared with the existing calculation theory and experimental results. It is concluded that the active earth pressure calculated by this method is more accurate and more reasonable and scientific in the design and use of retaining wall.
【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU476.4;TU432
本文编号：2358223
[Abstract]:The study of earth pressure on retaining wall has been paid more and more attention. At present, Coulomb earth pressure theory and Rankine earth pressure theory are commonly used to calculate earth pressure. However, these two theories are both used under certain assumptions, and the calculation results will inevitably produce errors when applied to engineering practice. First of all, Coulomb theory holds that the state of uniform translation of retaining wall is not practical, because in the actual construction process, there can be many kinds of displacement modes of retaining wall. Second, the theory holds that when the soil behind the wall reaches the ultimate equilibrium state, it is also inaccurate to calculate the earth pressure finally by using the following equilibrium equations under the static equilibrium condition, because in reality, The soil can not reach the limit state in real sense, so the earth pressure calculated by this method is usually smaller than the actual value. Thirdly, the Coulomb theory usually regards the soil behind the wall as a whole, so the stress variation of the soil itself is ignored, and the calculation results are not accurate. However, although Rankine's theory improves Coulomb's theory and takes into account the stress variation of the soil itself, it ignores the friction resistance between the retaining wall and the filling interface, so it is also inaccurate. Therefore, in order to strengthen the rationality of the design of retaining wall, it is necessary to consider the factors that affect the change of earth pressure. In view of the influence of displacement mode and displacement on active earth pressure of retaining wall, an improved calculation theory is put forward on the basis of many scholars' research. Taking rigid retaining wall as an example, it is considered that three kinds of displacement modes may occur in actual construction: rotation around the bottom of the wall (RB mode), rotation around the top of the wall (RT mode) and peaceful movement (T mode). It is also defined that there will be a "intermediate transition state" when retaining wall moves from the initial static state to the ultimate active state, which is called the non-limit active state. It is considered that with the increase of wall displacement, the friction angle of fill soil is gradually developed in the process of moving away from the soil. The concept of exertion value of friction angle is introduced, and the relationship between friction angle and displacement is established. At the same time, the active earth pressure on the back of the wall decreases gradually from the static earth pressure to the limit active earth pressure because of the increase of displacement, and the relationship between friction angle and displacement can be utilized. The value of active earth pressure in non-limit active state of soil is calculated. Finally, the active earth pressure, the distribution of active earth pressure and the position of working point of the rigid retaining wall in non-limit state can be obtained under different displacement modes and different displacements. The results obtained by this method are compared with the existing calculation theory and experimental results. It is concluded that the active earth pressure calculated by this method is more accurate and more reasonable and scientific in the design and use of retaining wall.
【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU476.4;TU432
【参考文献】
相关期刊论文 前1条
1 岳祖润,彭胤宗,张师德;压实粘性填土挡土墙土压力离心模型试验[J];岩土工程学报;1992年06期
，本文编号：2358223
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