灌溉渠道渠基土—混凝土衬砌冻结接触面抗剪强度试验研究

发布时间：2018-04-29 06:25

本文选题：接触面 + 冻结　；参考：《山东农业大学》2017年硕士论文

【摘要】：山东省作为中国的农业大省,灌溉渠道遍布。同时,山东处于季冻区域,冬季气候寒冷,输水渠道极易发生冻害破坏,而破坏往往是从衬砌开始,例如发生衬砌的滑塌、折断、产生裂缝、隆起架空、表面剥落等,随之渠道的抗渗性能迅速下降,导致渠道渗漏而浪费水资源。在此背景下,本文结合实际工程中的渠道衬砌破坏特点,利用直剪仪模拟了渠道渠基土与混凝土衬砌冻结接触面的剪切破坏过程:将取自灌区的土样与混凝土衬砌按要求处理后分别置于上下剪切盒,经过充分预压、冻结后进行剪切试验。通过调节土体的含水率、冻结时的温度、冻结的时间以及剪切时的法向应力,研究了渠基土与混凝土衬砌冻结接触面抗剪强度随不同含水率、冻结温度、法向应力及冻结时间等影响因素的变化规律。本文的成果主要有:(1)剪切的初始阶段,接触面存在局部剪应力释放现象,释放量大小受土体含水率、法向应力、冻结时间因素影响,但不受冻结温度的影响。在本试验参数范围内:土体含水率越高,释放量越大;法向应力越大,释放量越大;冻结时间越长,释放量越小。(2)冻结接触面的抗剪强度与土体含水率、冻结温度、法向应力、冻结时间密切相关。在本试验参数范围内,接触面峰值抗剪强度随着土体含水率、法向应力、冻结时间的增加而增大,随冻结温度的降低而增大;且接触面峰值抗剪强度与法向应力、冻结时间在本试验参数范围内呈线性关系。(3)冻结接触面的抗剪强度实质上是冻土中的冰晶与混凝土衬砌接触面之间的胶结力,以及土体与混凝土衬砌接触面之间的黏聚力与摩擦力;而这种胶结力是土体中的水分在低温下形成的冰晶与混凝土衬砌接触面通过胶结作用形成的。峰值抗剪强度大小主要受胶结力影响;黏聚力和摩擦力主要受法向应力、冻结时间的影响。
[Abstract]:As a big agricultural province in China, Shandong Province has many irrigation channels. At the same time, Shandong is in a seasonally frozen area, and the winter climate is cold, and the water conveyance channel is liable to be damaged by freezing, and the damage often begins with the lining, such as the collapse of the lining, the breaking of the lining, the occurrence of cracks, the uplift of the sky, the surface spalling, and so on. The impermeability of the channel decreases rapidly, which leads to the leakage of the channel and the waste of water resources. In this context, combining with the characteristics of channel lining failure in practical engineering, The shear failure process of frozen contact surface between channel foundation soil and concrete lining was simulated by means of direct shear apparatus: soil samples from irrigation area and concrete lining were treated according to requirements and placed in upper and lower shear boxes respectively, after full preloading, Shear tests were carried out after freezing. By adjusting soil moisture content, freezing temperature, freezing time and normal stress during shearing, the shear strength of frozen interface between soil and concrete lining is studied with different moisture content and freezing temperature. The change of normal stress and freezing time. The main results of this paper are as follows: (1) in the initial stage of shear, there is a phenomenon of local shear stress release at the contact surface. The amount of release is affected by soil moisture content, normal stress, freezing time, but not by freezing temperature. In the range of the test parameters: the higher the moisture content of soil, the greater the release amount; the greater the normal stress, the greater the release amount; the longer the freezing time, the smaller the release amount.) the shear strength and soil moisture content, freezing temperature, normal stress of the frozen contact surface, The freezing time is closely related. In the range of test parameters, the peak shear strength of contact surface increases with the increase of soil moisture content, normal stress and freezing time, and increases with the decrease of freezing temperature, and the peak shear strength and normal stress of contact surface increase with the increase of soil moisture content, normal stress and freezing time. The freezing time is linearly related within the range of the test parameters. (3) the shear strength of the frozen contact surface is essentially the cementing force between the ice crystal and the concrete lining interface in the frozen soil. And the cohesion and friction between soil and concrete lining contact surface, which is formed by the interface between ice crystal and concrete lining formed by water in soil at low temperature. The peak shear strength is mainly affected by the bonding force, and the cohesion and friction are mainly affected by the normal stress and freezing time.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S277

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