| 摘要: |
| 针对某工程砂卵砾石覆盖层中大型调压井沉井规模大、所处地层均匀性差、大体积孤石数量多、受地层性质及施工因素影响大等特点，以及施工面临的井身偏移倾斜、刃脚被孤石破坏及井壁与地层脱空等问题，首先进行了成因分析，解析比较了施工过程中沉井井壁土压力的变化；最后通过数值方法对沉井下沉过程中地层含有孤石时的施工方法进行了对比分析。结果表明：当土压力由先前的静止土压力转变为被动土压力时，井壁偏于不安全；沉井下沉过程中地层含有孤石时，应将前期先开挖土体再破除孤石的下沉开挖方法调整为先破除孤石再开挖土体，调整后可大幅降低沉井井壁和刃脚的应力，避免了井壁和刃脚出现破坏。 |
| 关键词: 沉井 偏移倾斜 孤石 井壁脱空 |
| DOI： |
| 分类号:TV732+.5 |
| 基金项目:水利部公益性行业科研专项经费项目专题(201501034-04)；陕西省科技统筹创新工程重点实验室项目(2014SZS15-Z01)；西安理工大学博士基金资助项目(106-211104) |
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| Mechanical characteristics of large caisson for surge shaft and its improvement of construction methods |
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PAN Feng1, DANG Fa-ning1, LU Liang2, DUAN Bin3, YANG Xiao-mei3
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1.Institute of Geotechnical Engineering, Xi'an University of Technology, Xi'an;2.Gansu Insitute of Architectural Design and Research, Lanzhou;3.Northwest Engineering Corporation Limited of Power China, Xi'an
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| Abstract: |
| In view of the special problems encountered in large caisson for the surge shaft construction in sand gravel overburden, a hydropower project is taken as an example. Considering large scale of the caisson, the poor uniformity of formation, the quantity of boulders and it was greatly effected by the formation property and construction factors, and the well wall being deviation and inclination, failure of the cutting edge and the well edge disengagement from formation during prophase construction which had seriously affected the construction safety, firstly, the problems of construction and their genesis were both analyzed. After then the change law of caisson wall earth pressure during construction is compared by an analytic method, the analysis results show that the earth pressure changed from static earth pressure to passive earth pressure when the deviation of the caisson appeared, and the well wall was not reliable in this case. Finally, the construction method for the caisson in the formation which contained boulders was compared by a numerical method during the sinking process, the analysis results show that adjusting the prophase sinking excavation method for the caisson to breaking boulders at first, then excavating soil, it can remarkally reduce the stress values of the caisson, effectively avoid the destruction of well wall and the cutting edge. Thus the improvement construction method for a large caisson of the surge shaft was proposed, which can be applied to same hydropower works under the special geological conditions. |
| Key words: caisson deviation and inclination boulders well wall disengagement |
