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摘要:
目前山区机场大量采用高填方工程,高填方地基沉降变形问题是个亟待解决的重要问题。首先,基于统一硬化(UH)模型,通过研究含石量与内摩擦角和黏聚力的关系,并基于扩展SMP准则和变换应力,将含石量引入到UH模型中,建立了考虑含石量的UH模型;应用当前屈服面与平均主应力轴交点的变化规律作为考虑含石量UH模型加卸载的判断准则,实现了硬化和软化的统一考虑;采用半隐式回映应力更新算法,将加卸载判断准则应用到应力更新算法中,实现了考虑含石量UH模型的有限元应用。其次,应用考虑含石量UH模型的有限元程序,对土石混合料的大型三轴试验进行了计算分析,计算结果和实测结果进行对比,验证了有限元程序的有效性。最后,应用考虑含石量UH模型的有限元程序,对山区机场高填方地基进行了三维有限元分析,得到了地基沉降监测点的竖向位移随时间的变化曲线,并与不考虑含石量UH模型、修正剑桥(MCC)模型计算得到的曲线及工程实测数据进行了比较,得到了高填方地基的竖向位移云图、侧向位移云图、孔隙水压力云图和超静孔隙水压力随时间的变化曲线,从而得到了机场高填方地基的位移和超静孔隙水压力变化规律,说明了考虑含石量UH模型在分析山区机场高填方地基变形方面的合理性。
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关键词:
- 统一硬化(UH)模型 /
- 含石量 /
- 有限元 /
- 高填方 /
- 地基变形
Abstract:At present, a large number of high-fill projects are used in mountainous airports, and the settlement and deformation of high-fill subgrades is an important issue to be solved. In this paper, based on the Unified Hardening (UH) model, by studying relationships between the stone content and the internal friction angle and cohesion, and based on the extended SMP criterion and transforming stress, the stone content is introduced into the UH model, and the UH model considering stone content is established. The change law of the intersection of the current yield surface and the mean principal stress axis is used as the judgment criterion for loading and unloading of the UH model considering stone content, which makes the unified consideration of hardening and softening be realized. And the semi-implicit back reflection stress update algorithm is adopted. The loading and unloading criterion is applied to the stress update algorithm. And the finite element application of the UH model considering stone content is realized. Then the finite element analysis of the large-scale triaxial test of the soil-stone mixture is carried out by the finite element program of the UH model considering stone content, and the validity of the finite element program is verified by comparing the calculated results of the finite element with the actual test results. Finally, using the finite element program of the UH model considering stone content, the three-dimensional finite element analysis is carried out for the high-fill subgrade of airport in the mountain area, and the vertical displacement curve of the ground settlement monitoring point is obtained. The calculated curves are compared with the curves by the UH model without considering stone content, the Modified Cambridge (MCC) model and the measured data. And the vertical displacement contour, the lateral displacement contour, the pore water pressure contour and the change curve of pore water pressure with time of high-fill subgrade are obtained, and thereby the displacement and pore water pressure change laws of the airport's high-fill subgrade are obtained. The rationality of the UH model considering the stone content in analyzing the deformation of the high-fill subgrade of the mountainous airport is explained.
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Key words:
- Unified Hardening (UH) model /
- stone content /
- finite element /
- high-fill /
- subgrade deformation
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表 1 土体材料参数
Table 1. Soil material parameters
参数 数值 M 1.17 λ 0.03 κ 0.01 ν 0.3 e0 0.89 c/kPa 56.37 PR/% 51.8 表 2 填土土体材料参数
Table 2. Soil material parameters of filling
土层 E/MPa ν γ/(kN·m-3) 填土层1 40 0.2 22 填土层2 35 0.2 21.6 填土层3 28 0.3 21.1 注: γ为重度,E为弹性模量。 表 3 地基土体材料参数
Table 3. Soil material parameters of subgrade
土层 M λ κ ν e0 c/kPa PR/% γ/(kN·m-3) 渗透率/(10-4 m·d-1) 下层地基 1.42 0.22 0.022 0.2 0.81 40 40 21 1 上层地基 0.98 0.4 0.04 0.2 0.85 18 0 18.5 2 -
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