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（中國鐵建投資公司， 北京 100855)
［摘要］在泥水平衡盾構(gòu)施工過程中，如何確保施工安全并減少對周邊環(huán)境的影響受到國內(nèi)外學(xué)者的廣泛關(guān)注，地層土體穩(wěn)定性問題顯得尤為重要，但對于砂質(zhì)地層開挖面穩(wěn)定性的失穩(wěn)機(jī)理及其穩(wěn)定性分析尚處于經(jīng)驗(yàn)階段。利用大尺寸模型試驗(yàn)，研究了不同水頭高度（無水、0.9m和1.1m）下兩種地層中開挖面的主動破壞的發(fā)展模式和受力情況，并通過FLAC 3D數(shù)值模擬對試驗(yàn)結(jié)果進(jìn)行了驗(yàn)證。結(jié)果表明：在砂質(zhì)地層泥水平衡盾構(gòu)開挖面穩(wěn)定性的問題中水頭高度扮演了十分重要的角色，根據(jù)水頭高度不同，可將開挖面主動破壞發(fā)展模式劃分為無水模式、低水頭模式和高水頭模式；開挖面失穩(wěn)時(shí)存在土拱效應(yīng)，地表對開挖面主動破壞的響應(yīng)存在滯后效應(yīng)，在干砂地層中土拱效應(yīng)甚至于會消除對地表的影響；同時(shí)在確定支護(hù)力時(shí)，應(yīng)在靜止土壓力和靜水壓力的基礎(chǔ)上考慮超孔隙水壓力的影響。
［關(guān)鍵詞］泥水平衡盾構(gòu)； 砂質(zhì)地層； 主動破壞； 失穩(wěn)發(fā)展模式； 土拱效應(yīng)
中圖分類號： U45.6 文獻(xiàn)標(biāo)識碼： A文章編號： 1002-848X(2015)S2-0075-06
作者簡介：蔣向陽，高級工程師，Email：zhnyang110@163.com。
Analysis of effect of waterhead on stability of excavation face of slurry balanced shield
Jiang Xiangyang
(China Railway Construction Investment Group Co., Ltd., Beijing 100855, China)
Abstract: In slurry balanced shield tunneling, how to ensure the safety of construction and to reduce the influence on the environment have arisen wide attention of scholars both at home and abroad. But now it is still in the stage of experience as to the instability mechanism of the slurry shield tunneling excavation and its stability analysis. Based on the large-diameter modeling tests and FLAC 3D, the effect of the different waterhead (non-water, 0.9m and 1.1m) on stability of excavation face of slurry balanced shield was investigated, and the stability mechanics was proposed. The results show that: waterhead heights play an important role on excavation face instability features of slurry balanced shield in sandy stratum, regarding the different waterhead heights, the development mode of the excavation face instability features can be divided into non-water mode, lower-waterhead mode and higher-waterhead mode; soil arching is existed in the process of excavation face instability, the settlement of ground lags behind excavation face failure, the soil arching will block or eliminate the effects of ground settlement; excess pore water pressure need to be considered besides earth pressure and hydrostatic pressure when the supporting force is calculated.
Keywords: slurry balanced shield； sand body； active failure； failure develop model； soil arching
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