渗透力对新奥法隧道掌子面稳定性的影响

来源期刊:中南大学学报(自然科学版)2019年第5期

论文作者:黄戡 安永林 岳健 曾贤臣 李佳豪 张艺杰 王栋

文章页码:1221 - 1229

关键词:隧道工程;掌子面稳定性;渗透力;极限分析法;强度折减法;帷幕注浆

Key words:tunnel engineering; face stability; seepage force; limit analysis method; strength reduced method; curtain grouting

摘    要:因实际掌子面没有支护力,用支护力反映新奥法隧道掌子面稳定性存在缺陷,为此,提出用虚拟支护力表示。在分析渗流场基础上,结合强度折减法和极限分析上限法,推导存在渗透力的掌子面稳定安全系数公式,并应用于实际隧道工程;分析水位高度、帷幕注浆长度等参数对渗透力与掌子面稳定性影响的规律;最后对孔隙水压力与渗透力进行计算。研究结果表明:随着水位升高,单位平均渗透力增大,掌子面安全系数呈负指数降低;若仅考虑水平渗透力而忽略竖向渗透力,则所得结果偏不安全;帷幕注浆的安全系数比无注浆时的高,但渗透力比无注浆的大;随着掌子面前方帷幕注浆长度增加,水平渗透力减小,而竖向渗透力增加,安全系数略微减小;减小台阶开挖高度,可以提高掌子面的稳定性;随着黏聚力和内摩擦角增大,掌子面稳定安全系数提高,但增加梯度减小。

Abstract: Because the actual tunnel face is unsupported, there is a defect of using the support pressure to evaluate tunnel face stability by new Austria tunneling method, so virtual support pressure was used to express it. On the basis of the analysis of seepage field and combining the strength reduction method and the upper bound limit method, the formula of the stability safety factor containing the tunnel face of the seepage force was derived and applied in the actual tunnel engineering. The influence of water level and curtain grouting length on permeability and face stability were analyzed. Finally, some calculation methods of pore water pressure and permeability were discussed. The results show that when the water level increases, the average seepage force increases, and the safety factor of the tunnel face decreases as a negative index. If only the horizontal seepage force is considered and the vertical permeability is ignored, the result is not safe. The safety factor of curtain grouting is higher than that without grouting, but the seepage force is greater than that without grouting. With the increase of curtain grouting length in the front of the tunnel face, the horizontal seepage force decreases, while the vertical seepage force increases, and the safety factor decreases slightly. The stability of the tunnel face can be improved by reducing the excavation height. With the increase of cohesion and internal friction angle, the safety factor of tunnel face increases, but the increasing gradient decreases.

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