基于砂箱模型试验的肋板式挡土墙稳定性及破坏模式研究

发布时间：2019-05-23 13:33

【摘要】：支挡结构是岩土工程的一个重要组成部分。随着我国经济建设与基础设施的快速发展,对于复杂地质条件下支挡结构提出了更高要求,许多采用锚固技术、加筋土技术、悬臂结构以及组合结构等多种轻型的支挡结构开始广泛应用。肋板式挡土墙是一种由墙面板、肋板及肋板间土体组成的新型支挡结构,依靠伸入稳定区土体的肋板与肋板间土体的摩擦作用来平衡作用在面板上土压力。其主要特点是充分利用墙后土体的自稳定性、对边坡土体扰动小、地基承载力要求不高,结构简单等。目前,肋板式挡土墙的受力变形特征、破坏模式及稳定机理等尚不明确,未建立相应的设计计算方法。在总结和分析已有的挡土墙研究成果基础上,通过室内小型砂箱模型试验,探究纸质柔性面板肋板式挡墙模型与有机玻璃刚性面板肋板式挡墙模型两种面板类型肋板式挡墙稳定性的影响因素。重点分析肋板式挡土墙肋板间距和肋板长度两个主要结构参数对墙体稳定性的影响,并得到相应的合理布置方式。另外,试验研究了肋板式挡土墙破坏模式及破裂面的位置与形态,初步得到以下结论:(1)肋板式挡土墙是以肋板为主要锚固体、面板为挡土体,依靠肋板与填土间摩擦作用来平衡墙面板土压力的一种新型支挡结构。室内砂箱模型试验表明,肋板间距和长度是影响肋板式挡土墙稳定性的两个关键因素。(2)采用长750mm、宽500mm、高500mm的胶合木板模型箱,以350g/m2白卡纸作为墙面板、800g/m2双灰纸作为肋板以及石英砂作为填料开展了柔性面板下砂箱模型试验。试验表明,受面板刚度低的影响,作用在墙面板的土压力使墙面板产生较大的局部变形,随肋板间距增大而更为显著,对挡土墙的自稳不利。极限稳定状态下长肋疏布布置方式所需的肋板面积较大,受最小肋板长度的限制,短肋密布方式所需肋板面积也随肋板间距变小而增大,因此,肋板处于长肋疏布与短肋密布方式过渡区的布置方式所需肋板面积较小,为最优布置方式。(3)选用长750mm、宽500mm、高500mm的有机玻璃板模型箱,以有机玻璃板作为墙面板、800g/m2双灰纸作为肋板以及粉细砂作为填料开展了刚性面板砂箱模型试验。试验表明,砂箱边壁的边界效应不显著,可视为对称面,肋板间距为最外侧肋板至砂箱边壁距离的两倍的等间距布置方式为合理的布置方式,即对称面布置法,较等间距布置法更为合理。刚性面板肋板式挡土墙的稳定性受面板自身刚度影响较小,可以充分发挥肋板与土体的摩擦作用,在极限稳定状态下,长肋疏布方式所需肋板面积最小。(4)利用长800mm、宽600mm、高600mm的钢制模型箱,制作300mm墙高有机玻璃材质肋板式挡土墙模型,以标准砂作为墙后填料开展了 4组砂箱模型试验。经过离心加载后,给予肋板式挡土墙足够位移使挡墙产生破坏,观察内部破裂面的位置及形态。在肋板式挡土墙水平位移较大时,推墙试验使肋板式挡土墙破坏等效于无人为外力影响下挡土墙自身失稳破坏,验证了随着肋板间距由疏至密的变化,在极限稳定状态下,肋板式挡土墙存在两种典型的力学作用模式:间距较大时,依靠肋板与稳定区土体摩擦效应提供锚固力平衡墙面板土压力,为长肋疏布的摩擦锚固型破坏模式,极限状态下的破裂面位于肋间土内;间距较小时,肋间土受到相邻肋板较强的摩擦约束,形成整体土墙,类似于利用墙体自重达到稳定的重力式挡土墙,为短肋密布的整体土墙型破坏模式,破坏时破裂面位于假想墙背后侧土体。
[Abstract]:The supporting structure is an important part of the geotechnical engineering. With the rapid development of the economic construction and the infrastructure of our country, it has put forward a higher requirement for the support structure under the complex geological conditions, and many kinds of light supporting structures, such as the anchoring technology, the reinforced earth technology, the cantilever structure and the combined structure, are widely used. The rib-type retaining wall is a new type of supporting structure composed of a wall panel, a rib plate and a soil body between the rib plates, and the soil pressure acting on the panel is balanced by the friction between the rib of the soil body extending into the stable region and the rib plate. The method is mainly characterized in that the self-stability of the soil body after the wall is fully utilized, the soil disturbance of the side slope is small, the bearing capacity of the foundation bearing is not high, the structure is simple, and the like. At present, the stress deformation characteristics, the failure mode and the stability mechanism of the rib-type retaining wall are not clear, and the corresponding design calculation method is not established. Based on the summary and analysis of the existing retaining wall research results, the influence factors of the paper flexible panel rib plate retaining wall model and the plate type rib plate retaining wall model of the plexiglass rigid panel rib plate type retaining wall model are investigated through the indoor small sand box model test. The influence of two main structural parameters of rib-plate retaining wall and rib length on the stability of the wall is analyzed, and the corresponding reasonable arrangement is obtained. in addition, that failure mode of the rib-plate retaining wall and the position and shape of the rupture surface are studied, and the following conclusions are obtained: (1) the rib-type retaining wall is a solid with the rib plate as the main anchor, and the panel is a soil-retaining soil body; A new type of support structure is used to balance the soil pressure of the wall panel by means of the friction between the rib and the fill. The model test of the indoor sand box shows that the spacing and length of the rib are two key factors that influence the stability of the rib-type retaining wall. (2) The model test of the sand box under the flexible panel was carried out by using 350 g/ m2 of white cardboard as the wall panel,800 g/ m2 of double-ash paper as the rib and quartz sand as the filler, using a glued wood board model box of 750 mm long,500 mm wide and 500 mm high. The test shows that under the influence of low stiffness of the panel, the soil pressure acting on the wall panel causes the wall panel to generate large local deformation, which is more obvious with the increase of the rib spacing, and the self-stability of the retaining wall is unfavorable. the rib area required by the long-rib-thinning arrangement mode in the limit-stable state is large, is limited by the length of the minimum rib, the area of the rib required for the short-rib-densely-densely distributed mode also increases with the spacing of the rib, and therefore, The rib plate is in the arrangement mode of the long-rib sparse cloth and the short-rib dense mode transition area, and the required rib area is small, and is an optimal arrangement mode. (3) An organic glass plate model box with a length of 750 mm, a width of 500 mm and a height of 500 mm is selected, and a rigid panel sand box model test is carried out by using an organic glass plate as a wall panel,800 g/ m2 of double-ash paper as a rib and fine sand as a filler. The test shows that the boundary effect of the side wall of the sand box is not significant, it can be regarded as the symmetrical surface, and the spacing between the rib and the side wall of the sand box is two times the distance of the side wall of the sand box. The stability of the rigid panel rib plate retaining wall is less affected by the self-rigidity of the panel, and the friction effect of the rib and the soil body can be fully exerted, and the floor area of the long-rib-rib-type retaining wall is the smallest under the limit-stable state. (4) Using a steel model box with a length of 800 mm, a width of 600 mm and a height of 600 mm, a plate-type retaining wall model of a 300-mm high-glass-glass material was fabricated, and a four-group sand box model test was carried out with the standard sand as a post-wall filler. After the centrifugal loading, enough displacement of the rib-type retaining wall is given to cause the retaining wall to be damaged, and the position and the shape of the internal rupture surface are observed. when the horizontal displacement of the rib-type retaining wall is large, the wall-pushing test results in that the failure of the rib-type retaining wall is equivalent to the self-buckling failure of the retaining wall under the influence of no external force, There are two typical mechanical action modes of the rib-type retaining wall: when the distance is large, the soil pressure of the anchor force balance wall panel is provided by the friction effect of the rib and the stability area soil, the friction-anchoring type failure mode of the long-rib sparse cloth is long, and the fracture surface in the limit state is located in the intercostal soil; The spacing is small, and the intercostal soil is restrained by the friction of the adjacent rib plates to form a whole body, which is similar to the gravity-type retaining wall which is stabilized by the self-weight of the wall body, and is an integral abrasion-type failure mode with densely distributed short ribs, and the fracture surface is positioned on the back side soil body behind the virtual wall.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU476.4

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