改制三轴仪测试膨胀土吸水膨胀系数的试验研究

发布时间：2018-07-10 19:19

本文选题：膨胀土 + 三轴仪　；参考：《西南交通大学》2017年硕士论文

【摘要】：论文以云南呈贡强膨胀土为研究对象,采用常规试验法,断续吸水法,连续吸水法及改制三轴仪对膨胀土进行吸水膨胀应力与应变的测量,得到了膨胀土的应力、应变与含水率变化及吸水量的一般规律;主要研究成果如下:1.根据现有的膨胀理论,进行相应的简化,根据土体的三相指标推导出非饱和土膨胀变形的一般公式δ=ρd/ρωSrΔω+[ρd/ρωSrω0-(1-ρd/ρs)]并提出膨胀变形的简化计算公式δ=α · + c,提出膨胀变形系数的概念。2.通过无荷膨胀试验,断续吸水膨胀试验及三轴膨胀变形试验三种试验方法进行膨胀变形测量,得到膨胀变形与含水率变化的一般线性规律及膨胀变形系数的变化规律。3.讨论了膨胀力与吸力的理论关系,运用泊肃叶理论根据土中吸力的变化量来计算膨胀应力的理论公式得到P = aΔω + β的一般公式,提出膨胀应力系数的概念。4.通过平衡加压法试验、连续吸水膨胀力试验、及改制三轴仪膨胀力测试,三种试验方法同时得到了相类似的规律,膨胀力的大小与土体的吸水量呈现出明显的线性关系,证明了膨胀应力系数的可行性。5.通过三轴仪的改装实现了对膨胀土应力应变的测量,通过观测吸水量与变形量之间的关系看出,进入到土体中的水一部分参与膨胀变形,另一部分以自由水的形式填充到空隙中。6.利用改制三轴仪对膨胀土应力应变测量的结果相对于其他试验方法结果而言,膨胀应力应变系数是随着吸水的进行而逐渐变化的,这也符合理论公式中系数的变化关系,更有助于对土体本身膨胀机理的研究。而常规试验方法所得到的膨胀特性系数,则使其确定化,简化了应力应变的计算方法,更利于实际应用。
[Abstract]:In this paper, the swelling stress and strain of the expansive soil are measured by conventional test method, intermittent water absorption method, continuous water absorption method and modified triaxial apparatus, and the stress of the expansive soil is obtained by taking Chenggong strong expansive soil as the research object. The main research results are as follows: 1. According to the existing expansion theory, the corresponding simplification is carried out. According to the three-phase index of soil, the general formula 未 = 蟻 d / 蟻蠅 Sr 螖蠅 [蟻 d / 蟻蠅 Sr 蠅 0- (1- 蟻 d / 蟻 s)] of unsaturated soil is derived, and the simplified formula of expansion deformation 未 = 伪 c is put forward, and the concept of coefficient of expansion deformation is put forward. In this paper, the general linear law of expansion deformation and water content change and the variation rule of expansion deformation coefficient are obtained by measuring expansion deformation by three test methods, such as no charge expansion test, intermittent water absorption expansion test and triaxial expansion deformation test. The theoretical relationship between expansion force and suction is discussed. The general formula P = a 螖蠅尾 is obtained by using Poiseuille theory to calculate the expansion stress according to the variation of suction in soil, and the concept of expansion stress coefficient is put forward. By means of equilibrium pressure test, continuous water absorption and expansion test, and modified triaxial apparatus, the three test methods have obtained the similar law at the same time, and the magnitude of expansion force has obvious linear relationship with the amount of water absorption of soil. It is proved that the expansion stress coefficient is feasible. Through the modification of triaxial instrument, the stress and strain measurement of expansive soil is realized. By observing the relationship between water absorption and deformation, it can be seen that some of the water entering the soil is involved in the expansion deformation. The other part is filled into the void in the form of free water. Compared with the results of other test methods, the stress-strain coefficient of expansive soil measured by the modified triaxial apparatus is gradually changing with the water absorption, which also accords with the variation of the coefficient in the theoretical formula. It is helpful to study the expansion mechanism of soil itself. The coefficient of expansion characteristic obtained by the conventional test method makes it definite, simplifies the calculation method of stress and strain, and is more suitable for practical application.
【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】：TU443

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