越冬基坑悬臂桩支护水平冻胀力分布模式及影响因素研究

发布时间：2018-08-05 14:11

【摘要】：寒冷地区越冬基坑工程需考虑土体冻胀影响,当冻胀产生较大的水平冻胀力时将引起支护结构水平变形剧增、出现裂缝或局部剪断,严重时可造成基坑坍塌,直接威胁基坑安全。本文选取悬臂桩支护结构为研究对象,基于FLAC3D数值模拟软件研究水平冻胀力的分布模式及其影响因素。水平冻胀力分布模式:水平冻胀力沿桩长出现上下小、中间大的抛物线型分布。在1/3~2/3坑深范围内,出现最大力值,其最大值可达初始土压力的十倍左右。各影响因素:(1)温度影响:负温越低水平冻胀力越大,呈抛物线型分布模式。桩顶出现最大水平位移,不同温度下,桩顶最大位移与最大水平冻胀力呈线性作用关系。(2)土类影响:粗砂、黏土、粉质黏土和粉土最大水平冻胀力有很大区别,其力值大小依次为粗砂黏土粉质黏土粉土,开挖范围内,粗砂产生的水平冻胀力呈现先增加,后保持稳定的变化趋势,而粉土、粉质黏土和黏土,呈现的规律则为先小、后大再变小,呈抛物线型分布。(3)土体密度影响:随密度增加冻胀力增大,最大水平冻胀力与对应的土体密度之间呈二次函数关系。(4)含水量影响:超过一定值以后,土体产生冻胀力,冻胀力的大小随含水率增加而增加,最大水平冻胀力与含水率之间呈幂函数关系。(5)支护桩刚度影响:随桩体刚度增加,土体约束作用明显增强,桩顶水平位移不断减小,但水平冻胀力却持续增大。(6)开挖深度影响:基坑在不同的开挖深度下,形成的水平冻胀力有较大区别,深度越深力值越大,二者呈二次函数的关系。
[Abstract]:The effect of soil frost heaving should be considered in the engineering of wintering foundation pit in cold area. When frost heave produces large horizontal frost heaving force, horizontal deformation of supporting structure will increase sharply, crack or local shearing will appear, and foundation pit collapse may be caused when frost heaving is serious. It directly threatens the safety of foundation pit. In this paper, the cantilever pile supporting structure is chosen as the research object, and the distribution mode of horizontal frost heave force and its influencing factors are studied based on FLAC3D numerical simulation software. Horizontal frost heave force distribution model: horizontal frost heave force along the length of the pile up and down a large parabola distribution. In the depth range of 1 / 3 / 3 / 3, the maximum value is about 10 times the initial earth pressure. The influencing factors are as follows: (1) temperature influence: the lower the negative temperature, the greater the horizontal frost heaving force, and the parabola distribution pattern. The maximum horizontal displacement occurs at the top of the pile. At different temperatures, the maximum displacement of the pile top is linearly related to the maximum horizontal frost heaving force. (2) the influence of soil: coarse sand, clay, silty clay and silty clay have great differences in the maximum horizontal frost heaving force. In the excavation range, the horizontal frost heaving force produced by coarse sand increases first, then keeps stable change trend, but the rule of silt, silty clay and clay is small first, (3) the effect of soil density: the frost heave force increases with the density, and the relationship between the maximum horizontal frost heave force and the corresponding soil density is quadratic. (4) the effect of water content: when the soil density exceeds a certain value, The magnitude of frost heave force increases with the increase of water content, and the maximum horizontal frost heave force and moisture content show a power function relationship. (5) the influence of supporting pile stiffness: with the increase of pile stiffness, the restraint effect of soil is obviously enhanced. The horizontal displacement of pile top decreases continuously, but the horizontal frost heave force increases continuously. (6) the influence of excavation depth: under different excavation depth, the formation of horizontal frost heave force is quite different, the deeper the depth is, the greater the value of the force is, the relationship between them is a quadratic function.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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