【作者】 袁杰；

【导师】 张义同；

【作者基本信息】 天津大学 ， 固体力学， 2012， 硕士

【摘要】 随着隧道掘进掘进技术的广泛应用,推动了世界各国基础设施的不断完善,但在隧道的施工过程中也遇到了一些技术难题,其中岩石隧道掘进中围岩岩爆问题与土质隧道掘进中掘进面的失稳问题是比较突出的两个问题。国内外学者对岩爆的形成机理已进行了大量研究,但还没有对岩爆形成机理形成共识,无法对岩爆现象做出准确地预测;而对于复杂地质隧道掘进面稳定性的研究尚未成熟,尤其是关于地下水渗流对掘进面的影响分析较少。因此,本文针对岩爆形成机理与掘进面稳定性进行研究,主要研究内容如下:(1)隧道围岩的应力应变状态为隧道围岩稳定性的分析提供了重要依据,采用非线性的Hoek-Brown屈服准则与非关联塑性流动法则,对深埋圆形隧道围岩进行弹塑性解析分析,推导了围岩弹塑性区应力、位移的表达式,得出围岩应力的分布规律。(2)建立了双轴压缩载荷下隧道围岩边界附近的裂纹模型,基于断裂韧性理论,运用对偶渐进法对圆形自由边界附近裂纹的扩展进行分析,获得了裂纹发生失稳扩展的临界应力,也就是岩爆发生的临界应力条件。(3)采用FLAC3D对盾构隧道进行三维数值模拟,通过分析渗流与土体应变软化对盾构掘进面极限支护压力、位移、塑性区范围以及地表沉降的影响。研究发现,渗流更容易导致掘进面的失稳,增大了极限支护压力。(4)将复杂地质掘进面稳定性的研究成果应用于天津地铁九号线的实例分析中,研究考虑地下水渗流时不同支护压力下开挖面前方土体变形的情况,根据地表的沉降情况预测出施工中的支护压力范围,将预测值与实际施工中土仓压力的监测值进行对比验证,符合较好。更多还原

【Abstract】 With the wide use of tunneling technique, infrastructure construction has been continuously improved. At the same time, the application of the method has some difficult problems of technology. Two serious ones of them are rock burst in rock tunnel and the instability of excavation face in soil shield tunnel. A great deal of research on mechanism of rock burst has been conducted by many scholars. But up to now no consensus is formed to exactly predict rock burst. No mature theories have been identified from many researches about face stability of shield tunnel, especially in researching effect of groundwater seepage on tunnel face stability. So it is necessary to study mechanism of rock burst and face stability of tunnel. The main work is as follows:(1) The stress and strain state of tunnel surrounding rock is an important basis for analysis of stability of surrounding rock. Elastoplastic analysis of surrounding rocks of deep tunnel is carried out by non-linear Hoek-Brown yield criterion. The analytical equation for calculating the stress around openings is proposed. The stress state of surrounding rocks is also given.(2) Then a model of crack situated close to the straight boundary is established. The stages of crack growth are researched by using the dipole asymptotic method. When the crack is close to the free boundary, analysis of crack near circular arc boundary under biaxial compression is conducted with considering the influence of the boundary shape. The critical stress condition corresponding to the onset of the unstable growth of crack nearby free boundary is obtained. This condition is the critical stress level of rockburst.(3) Three-dimensional numerical simulation on shield tunnel is carried out by FLAC3D. The influence of groundwater seepage and strain softening in soils on limit supporting pressure, displacement, plastic zone of excavation face and ground settlement is analyzed. Effect of seepage on face stability is also discussed. The results show that seepage can easily lead to instability of excavation face, and also cause the limit support pressure to build up.(4) The research results of face stability are applied to actual engineering, e.g. the line 9 of Tianjin metro. The deformation of soil in front of face during tunneling is studied by considering seepage force. The support pressure range used in construction of this engineering is predicted according surface subsidence. And the results of prediction agree well with the actual monitoring values.更多还原