土工袋加筋橡胶砂动力特性的大型循环单剪试验研究

发布时间：2018-01-09 05:14

本文关键词：土工袋加筋橡胶砂动力特性的大型循环单剪试验研究　出处：《湖南工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：土工袋加筋橡胶砂复合隔震垫层,是将橡胶颗粒砂装进土工袋,一方面橡胶砂作为散体材料,水平刚度和竖向模量较小;另一方面橡胶砂在土工袋包裹作用下,土工袋竖向承压产生较大张力,进而提高竖向承载能力,增大压缩模量,减小竖向沉降。为了进一步对土工袋加筋橡胶砂作为隔振垫层提供理论指导,本文围绕土工袋加筋橡胶砂的承载能力和动力特性,通过大型循环单剪试验,对土工袋加筋橡胶砂进行了一系列研究,研究主要内容:1、对4种不同橡胶含量的土工袋加筋橡胶砂,在3种固结压力下进行了大型循环单剪试验,对比分析了6种剪切位移幅值下的滞回曲线,应力应变关系曲线以及阻尼比曲线的变化规律。研究表明:土工袋加筋橡胶砂动剪模量随橡胶含量增大而降低;土工袋加筋橡胶砂具有可变的水平刚度,作为基础有一定的现实可能性;阻尼比随剪应变先减小后增大,临界动剪应变在d?=0.014左右;阻尼比随橡胶含量增加逐渐降低,而且降低趋势随橡胶含量增加逐渐减缓,橡胶含量临界值在30%左右。2、对不同放置方式的土工袋加筋橡胶砂进行了大型循环单剪试验,试验设置了2种橡胶含量,3种竖向固结压力和6种剪切位移幅值,分别对放置方式对动剪模量和阻尼比的影响规律进行了对比分析。结果表明:竖向放置动剪模量最小,纵向放置最大;橡胶含量20%的阻尼比曲线竖向最高,其次为横向放置,纵向放置最低,橡胶含量30%的阻尼比曲线由高到低为:竖向、纵向、横向;阻尼比总体上是随动剪应变先减小后增大,动剪应变临界值为0.014左右。3、对不同预装紧度土工袋加筋橡胶砂进行了大型循环单剪试验,为确定土工袋的最佳预张紧度,试验设置了3种预张紧度,分别研究了3种预张紧度的动剪模量曲线和阻尼比曲线以及循环剪切之后的破坏形态等。试验结果表明:土工袋预张紧度越小,土工袋破坏程度越小。动剪模量随预张紧度的减小而减小,且三层与四层之间变化不大;预张紧度的减小会引起阻尼比的增加,土工袋加筋橡胶砂能够更好的发挥其消能减震作用;土工袋加筋橡胶砂的最佳预张紧度为三层土工袋对应的预张紧度,即最适宜的装袋容量为60%左右。4、通过对土工袋加筋橡胶砂试验数据与课题组土工格室加筋橡胶砂试验数据进行对比分析,土工格室增加了水平动剪模量,降低了橡胶砂阻尼比;土工袋加筋水平动剪模量最小,阻尼比最大,有利于隔振效果的发挥。本文通过大型循环单剪试验,研究了土工袋加筋橡胶砂复合隔震垫层的动力特性和竖向变形特性,对今后土工袋的研究,橡胶砂动力特性以及橡胶砂加筋方式的研究奠定一定的理论基础。
[Abstract]:The rubber sand composite isolation cushion is filled with rubber granular sand into the geotextile bag. On the one hand, the rubber sand is used as the bulk material, and the horizontal stiffness and vertical modulus are small. On the other hand, under the action of the rubber sand wrapped in the geotextile bag, the vertical bearing capacity of the bag is increased and the compression modulus is increased. To reduce vertical settlement. In order to further provide theoretical guidance for geotextile reinforced rubber sand as vibration isolation cushion, this paper passes a large scale cyclic shear test around the bearing capacity and dynamic characteristics of geotextile reinforced rubber sand. A series of studies on reinforced rubber sand with earth bags were carried out. The main content of the study was: 1. A large scale cyclic single shear test was carried out on four kinds of reinforced rubber sand with different rubber content under three kinds of consolidation pressure. The hysteretic curves, stress-strain curves and damping ratio curves of six shear displacement amplitudes are compared and analyzed. The results show that the dynamic shear modulus of reinforced rubber sand decreases with the increase of rubber content. Rubber sand reinforced by geotextile bags has variable horizontal stiffness, which has certain realistic possibility as foundation; The damping ratio decreases first and then increases with shear strain. About 0.014; The damping ratio decreases gradually with the increase of rubber content, and the decreasing trend decreases with the increase of rubber content, the critical value of rubber content is about 30%. 2. Large scale cyclic single shear tests were carried out on rubber sand reinforced by geotextile bags with different placing methods. Two kinds of rubber content and three kinds of vertical consolidation pressure and six shear displacement amplitudes were set up in the test. The effects of placement mode on dynamic shear modulus and damping ratio are compared and analyzed respectively. The results show that the vertical placement has the smallest dynamic shear modulus and the longitudinal placement is the largest. The damping ratio curve of rubber content 20% is the highest in the vertical direction, followed by the horizontal placement, and the lowest in the longitudinal position. The damping ratio curve of the rubber content 30% is: vertical, vertical and horizontal; The damping ratio is that the following shear strain decreases first and then increases, and the critical value of dynamic shear strain is about 0.014. 3. A large scale cyclic single shear test of rubber sand reinforced with different pre-compaction geotextile bags is carried out. In order to determine the optimum pretension of soil bag, three kinds of pretensioning degree were set up in the experiment. The dynamic shear modulus curves and damping ratio curves of three pretensionities and the failure patterns after cyclic shear are studied respectively. The experimental results show that the pretension degree of geotextile bags is smaller. The smaller the failure degree of the geotextile bag is, the smaller the dynamic shear modulus decreases with the decrease of pretension, and the little change is found between the three and four layers. The decrease of pretension will lead to the increase of damping ratio, and the reinforced rubber sand of geotextile bags can play a better role in energy dissipation and vibration reduction. The optimum pretension of reinforced rubber sand for geotextile bags is the pretension degree corresponding to three layers of geotextile bags, that is, the most suitable bagging capacity is about 60%. 4. By comparing the test data of reinforced rubber sand with soil bag reinforced rubber sand and the test data of geogrid room reinforced rubber sand, the horizontal dynamic shear modulus is increased and the damping ratio of rubber sand is reduced. The horizontal dynamic shear modulus and damping ratio of reinforced geotextile bags are the minimum and the damping ratio is the largest, which is beneficial to the development of vibration isolation effect. In this paper, the large scale cyclic single shear test is carried out. The dynamic characteristics and vertical deformation characteristics of rubber sand composite isolation cushion reinforced by earth bags are studied. The theoretical basis for the future study of geotextile bags, dynamic characteristics of rubber sand and the reinforcement mode of rubber sand is established.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU435

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