【作者】 滕宏伟；

【导师】 姜德义；

【作者基本信息】 重庆大学 ， 安全工程， 2008， 博士

【摘要】 共和隧道地质条件十分复杂,隧道施工过程中遇到了围岩破坏界于软质岩大变形和硬质岩岩爆之间的特殊地质病害。针对这一病害特点,为了弄清其病害机理,设计合理的初期支护方式,本文主要做了以下几个方面的研究工作:①对共和隧道工程地质难题进行研究,分析了共和隧道病害形式;②对共和隧道围岩的力学性质进行了试验研究,完成了围岩的单、三轴试验,饱水软化试验及蠕变试验;③应用离散元数值计算方法对隧道开裂段施工全过程进行了研究,分析了隧道围岩应力演化过程、隧道围岩可能的破坏模式、节理参数对隧道变形的影响以及隧道锚杆支护结构的受力情况等问题;④通过现场量测和试验研究,分析了隧道初期支护失稳开裂的机理;⑤研究了隧道衬砌结构的长期动力可靠性问题,并计算了隧道开挖爆破地震扰动下共和隧道大变形开裂段衬砌结构的可靠度。通过对以上内容的研究,获得了以下一些主要成果:①获得了共和隧道页岩的基本力学参数,其刚度和强度均较低,刚度为27380 MPa,单轴抗压强度为47.35MPa;②得到了页岩动弹模量和抗压强度随饱水时间的变化而变化的规律,并给出了相应的软化方程;③得到了页岩在15MPa、20 MPa、25 MPa和30 MPa恒压下的蠕变规律,并得到了相应的蠕变本构方程和参数取值;④隧道所处区域整体应力较高,最大应力为17MPa,隧道开挖后最大应力为12MPa,形成了较大范围的应力卸荷区,隧道右上部的应力明显大于左上部,偏压明显;⑤隧道破坏时层面最小厚度为0.35~0.45mm,隧道破坏位置为右拱肩,位移量为在10.8cm~14.4cm之间;⑥节理参数对隧道围岩变形影响较小;⑦锚杆长度为6.5m较合适,锚杆衬砌结构的受力在拱腰段处最大,右上部的锚杆结构受力大于左上部受力;⑧离散元能很好的模拟非连续介质力学行为,数值模拟结果与工程实际观测情况吻合良好。⑨大变形开裂段开挖初期支护后,围岩变形较为缓慢,但持续时间很长,虽然收敛速率有减小的趋势,但到最后量测时为止(50多天),试验段所有断面均处于不收敛状态,并出现纵向开裂现象,最大水平收敛达79.64mm,最大拱顶下沉值达67.45mm,试验段初期支付设计难以满足需要,且隧道偏压严重;⑩隧道试验段围岩松动范围比正常隧道要大很多(正常隧道一般小于3m),试验段锚杆设计长度为3.5m,小于隧道围岩松动范围,锚杆难以起到悬吊作用;11共和隧道的病害是由于上覆地层自重应力、顺层地层偏压、岩体微裂隙发育、岩体蠕变、饱水软化等多种因素组合影响下而产生的一种特殊的隧道地质病害,其合理初期支护方式为Ⅲ(H1);12基于单侧界限的首次超越破坏准则建立了隧道衬砌结构的动力可靠度分析模型,掌子面爆破地震对共和隧道大变形开裂段衬砌结构的动态可靠度影响甚微;13在进行结构动力可靠性设计时,采用极值概率分布函数服从瑞雷分布的计算方法更为保险。更多还原

【Abstract】 The geological conditions of Gonghe tunnel are very complex. It meets the special geological disease which is between the soft rock large deforming and the hard rock bursting, when the tunnel was constructing. To get the mechanism of the special geological disease and design the reasonable initial support, this paper has done research in the following areas:①The engineering geological problems and the disease forms of Gonghe tunnel are analyzed.②Test on the mechanical properties of the rock tunnel, and the uniaxial compaction test, the triaxial test, the water-saturated soften rock test and creep test of the surrounding rock are completed.③The constructing process of the Gonghe tunnel’s cracked segment is studied by DEM. The evolution process of the stress in the surrounding rock, the possible broken mode of the surrounding rock, the impact of the joint’s parameters on the tunnel distortion and the force situation of the supporting structure in tunnel are analyzed.④The initial support crack mechanism of Gonghe tunnel is analyzed by field -measurement and field -test.⑤The secondary lining structure dynamic reliability is studied, and the secondary lining structure dynamic reliability in the large deformation zone of Gonghe tunnel impacted by the detonation at the heading is computed.The results are as follow:①The basic mechanics parameters of the surrounding rock are got, the rigidity and strength are a little low, and the rigidity is 27380 MPa, the uniaxial compressive strength is 47.35MPa.②The change rule of shale Dynamic elastic modulus and uniaxia compressive strength whit water-saturated time is got. The rock soften equations are got.③The creep rules of Shale under the 15MPa, 20 MPa, 25 MPa and 30 MPa pressure are got. And corresponding creep constitutive equations and parameters are got.④In the tunnel region the crustal stress is a little high, and the maximum stress is 17MPa. After the tunnel is caved, the maximum stress reduces to 12MPa, there is a big stress unloading zone and the stress on right upper tunnel is bigger than left upper tunnel.⑤The minimum thickness of the broken stratification is 0.35 ~ 0.45mm, the broken location is the right spandrel of tunnel, and the displacement is between 10.8cm and 14.4cm.⑥The parameters of joint have a little impact on the distortion of surrounding rock.⑦The suitable length of anchor is 6.5m, the maximum stress of the anchor is at the spandrel of tunnel, and the stress on right upper tunnel is bigger than left upper tunnel.⑧The DEM can simulate the non-continuum mechanics very well, and the numerical simulation results agree with the field maturation data.⑨The surrounding rock distorts slowly but sustains for a long time after the initial support is completed. Although the convergence rate of the surrounding rock has decreased trend, in the end all the test sections are not convergent and there is vertical crack, the maximum level convergence is 79.64mm, and the maximum crown settlement is 67.45mm.⑩The loose rock area in the test section is much larger than in the normal section (generally less than 3m in the normal section). The anchor length in the test section is 3.5m, which is less than the scope of loose rock, so the anchor can’t play the role of suspension.11 The disease of Gonghe tunnel are caused by the gravitational stress, bed-parallel bias, micro-fracture in rock, rock creep and water-saturated rock soften, which is a special tunnel geological disease, and it’s reasonable support isⅢ(H1).12 Based on the failure criterion of single confines exceeded at first, the analytic model for structure dynamic reliability is established. The detonation at the tunnel heading has little impact on the secondary lining structure dynamic reliability in the large deformation zone.13 When design the structure dynamic reliability, it’s more insurance to use the Rayleigh distribution function.更多还原