基于“可能湿陷变形”的黄土渠道地基湿陷性评价方法研究

发布时间：2018-03-19 06:19

本文选题：湿陷性黄土　切入点：增湿变形　出处：《中国水利水电科学研究院》2017年博士论文　论文类型：学位论文

【摘要】：目前,黄土渠道地基湿陷性评价和处理方面仍采用"最大湿陷变形"的思想,与工程实际有一定的差距。本文基于"可能湿陷变形"的设计思想和方法,探讨了湿陷性黄土地基的评价和处理方法,取得的成果摘要如下:(1)开展了原状黄土增湿变形特性的试验研究。首先引入了"增湿水平"这一变量来描述土体的湿度状态;其次以新疆伊犁黄土为对象,开展了侧限条件下的分级浸水试验,测得了不同竖向压力下各增湿水平Sw所对应的增湿变形系数δup、基质吸力s以及静止土压力系数K0,通过分析Sw-δuP、Sw-s、Sw-K0相关关系,建立了侧限条件下增湿过程中的增湿变形本构模型、土水特征曲线模型以及静止土压力系数表达式;然后以陕西张桥黄土为对象,通过三轴等应力比条件下的分级浸水试验,测得不同三轴应力状态下各增湿水平所对应的增湿体应变εvz、增湿剪应变εrz,在对Sw-εvz、Sw-εrz相关关系进行数学描述的基础上,建立了三轴应力条件下增湿过程中的增湿变形本构模型;最后在伊犁某黄土渠道地基上,进行了现场浸水试验,测得了现场的变形场和湿度场,揭示了该场地浸水过程的湿陷变形规律。(2)进行了黄土地基增湿变形离心模型试验研究。对伊犁某渠道湿陷性黄土地基典型层原状黄土开展了饱和度为40%、60%与100%的3组离心模型试验,在模型中设置分层变形观测点和土压力传感器,模拟自重应力下实际地基在增湿过程中的分层变形特性和土压力变化规律;在黄土地基增湿变形离心模型试验的基础上,以黄土地区修正系数β0为桥梁,提出了一个基于离心模型试验的黄土湿陷试验新方法,并与现场浸水试验成果相比较,较符合工程实际。(3)提出了黄土渠道地基湿陷性评价新方法。根据渠道工程特点,采用非饱和土渗透理论和本文建立的黄土增湿变形本构模型,提出了基于"可能湿陷变形"的黄土渠基湿陷性评价方法;参照《渠道防渗工程技术规范》(GB/T 50600-2010)和《渠道抗冻胀设计规范》(SL 23-2006),考虑到当前渠道工程普遍采用板膜结构的实际,以"可能湿陷变形"设计思想,提出了渠道地基湿陷等级划分标准和渠道重要性类别划分标准;采用"可能湿陷变形"的黄土渠道地基湿陷性评价新方法,以新疆伊犁一大型引水渠道工程为例进行了渠基湿陷性评价,结果表明本文提出的方法较为合理可行。
[Abstract]:At present, the idea of "maximum subsidence deformation" is still adopted in the evaluation and treatment of collapsibility of loess canal foundation, which is different from engineering practice. This paper is based on the design idea and method of "possible collapse deformation". The evaluation and treatment methods of collapsible loess foundation are discussed. The results are summarized as follows: (1) the experimental study on the humidification deformation characteristics of undisturbed loess is carried out. Firstly, the "humidification level" is introduced to describe the soil moisture state. Secondly, taking the Yili loess in Xinjiang as the object, the paper carried out the step immersion test under the condition of lateral limit. The humidification deformation coefficient 未 up, matrix suction s and static earth pressure coefficient K0 corresponding to different humidification levels under different vertical pressures were measured. By analyzing the correlation relationship between Sw- 未 UPU Sw-slSw-K0 and humidifying deformation, a humidification deformation constitutive model was established under the lateral limit condition. The soil-water characteristic curve model and the expression of the static earth pressure coefficient, and then taking Zhangqiao loess in Shaanxi as an example, the steeped soaking test under the condition of triaxial equal stress ratio is carried out. The humidifying body strain 蔚 VZ and the humidification shear strain 蔚 RZ under different triaxial stress state are measured. Based on the mathematical description of Sw- 蔚 VZN Sw- 蔚 rz correlation relationship, the constitutive model of humidification deformation under triaxial stress condition is established. Finally, the field soaking test was carried out on a loess canal foundation in Yili, and the deformation field and humidity field were measured. The centrifugal model test of wetting deformation of loess foundation was carried out. The saturation of the typical loess layer of collapsible loess foundation in Yili was 40% 60% and 100% respectively. Group centrifugal model test, The delamination deformation observation points and earth pressure sensors are set up in the model to simulate the delamination deformation characteristics and the soil pressure variation law of the actual foundation in the process of humidification under the self-gravity stress, and on the basis of the centrifuge model test of the loess foundation humidification deformation, A new method of loess collapsibility test based on centrifuge model test is put forward with the correction coefficient 尾 _ 0 in loess area as bridge, and the results are compared with the results of in-situ soaking test. A new method for evaluating the collapsibility of loess canal foundation is put forward. According to the characteristics of channel engineering, the unsaturated soil permeation theory and the constitutive model of loess humidification deformation established in this paper are adopted. The evaluation method of collapsibility of loess canal base based on "possible collapsing deformation" is put forward, with reference to the Technical Code for Canal seepage Control Engineering (GB / T50600-2010) and the Design Code for Canal Frost Resistance (SL23-2006C), considering the fact that the current channel engineering generally adopts slab-membrane structure, Based on the design idea of "possible collapsible deformation", this paper puts forward the criteria for classification of grade and importance of channel foundation, and adopts a new method of evaluation of collapsibility of loess canal foundation based on "possible collapse deformation". Taking a large diversion channel project in Yili, Xinjiang as an example, the collapsibility of canal foundation is evaluated. The results show that the method proposed in this paper is reasonable and feasible.
【学位授予单位】：中国水利水电科学研究院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TV223

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