软弱围岩隧道侧压力系数反演分析及变形特性研究
发布时间：2018-12-06 21:13
【摘要】：软弱围岩在公路隧道施工中所占的比重较大,且多呈现节理发育和高地应力等特点。目前,对软弱围岩小净距隧道施工过程中的围岩特性与变形机制认识不清。因此,研究软弱围岩隧道变形特性具有重要的意义。论文分析了软弱围岩隧道的变形机理及围岩-支护结构平衡稳定体系。依据新意法,研究了掌子面挤出变形、预收敛变形与收敛变形之间的关系。针对现场监测数据进行回归分析,利用位移反分析法反演侧压力系数λ。运用FLAC3D数值模拟,分析在不同λ下小净距隧道软弱围岩的变形特性,得到以下主要结论：(1)对现场监测数据进行回归分析,确定拱顶下沉与水平净空收敛最佳时态曲线方程分别为U=T/(0.1154+0.0271×T)和U=39.5276×e(-24498/T)。推算出拱顶与洞周极限位移值分别为36.96 mm和39.53mm。通过12次迭代收敛运算确定侧压力系数λ值为1.1305,满足收敛精度要求,且误差△=20.95%,目标函数f(λ)=31.431.7。(2)隧道开挖导致沿轴线方向围岩的变形呈逐步降低趋势,且存在挤出变形与轴向距离为线性关系。当λ1.0时,挤出变形与顶底预收敛近似线性,而与水平预收敛不呈线性；当λ=1.0时,挤出变形与顶底预收敛和水平预收敛均呈线性关系；当λ1.0时,挤出变形与水平预收敛为线性,比与顶底预收敛的线性关系更为显著。(3)考虑在衬砌施加前软弱围岩己发生较大的变形,数值试验施加衬砌的时机应选择在围岩发挥一定的自承能力后,试验结果表明衬砌施加前围岩变形约为极限位移值的1/3-2/3；当λ=1.0时,衬砌刚度选定为10.5GPa,在合理的支护时机下,能够提供足够的支护抗力,充分发挥围岩自承能力,防止软弱围岩发生大变形。(4)挤出变形与预收敛变形可呈线性关系,预收敛变形影响掌子面后方的收敛变形大小。衬砌支护后,掌子面后方围岩的收敛变形降低约50%,预收敛变形降低约25%,挤出变形降低约10%。于掌子面后方1m的范围内,围岩变形发生了较大幅度的改变。由于掌子面固端效应和地应力场的影响,于掌子面前方围岩可能出现位移方向相反的现象。(5)双行洞开挖与先行洞单独开挖相比,引起后者内帮水平位移减小而外帮水平位移增加,且内帮减小量大于外帮增加量。随λ值增加,拱顶与仰拱竖向位移相对增加,当λ=0.5时,位移增量曲线的对称效果显著；当λ0.5时,相同距离对应的拱顶位移增量绝对值大于仰拱位移增量绝对值：当λ≥1.0时,相同距离对应的仰拱位移增量绝对值则大于拱顶的。(6)后行洞扰动与双行洞开挖相比,水平位移变化量与垂直位移变化量曲线基本呈对称状。当λ=0.5时,基本上认为后行洞扰动与双行洞开挖产生的围岩变形一致;相对于双行洞开挖,后行洞扰动令右帮与拱顶产生相对较大的位移变化量。不同λ下的挤出变形并不相同,当λ=0.5时,挤出变形最小,且随λ增加,侧压力系数与挤出变形近似为线性。
[Abstract]:Soft surrounding rock occupies a large proportion in the construction of highway tunnel, and most of them show the characteristics of joint development and high ground stress. At present, the characteristics and deformation mechanism of soft surrounding rock in the construction of small clear distance tunnel are not clear. Therefore, it is of great significance to study the deformation characteristics of soft surrounding rock tunnel. The deformation mechanism of soft surrounding rock tunnel and the balance and stability system of surrounding rock-support structure are analyzed in this paper. According to the new method, the relationship among extrusion deformation, preconvergent deformation and convergent deformation is studied. Based on the field monitoring data, regression analysis is carried out, and the displacement inverse analysis method is used to retrieve the lateral pressure coefficient 位. By using FLAC3D numerical simulation, the deformation characteristics of soft surrounding rock in small clear distance tunnel under different 位 are analyzed. The main conclusions are as follows: (1) regression analysis of field monitoring data is carried out. The optimal temporal curve equations of vault subsidence and horizontal clearance convergence are determined to be U=T/ (0.1154 0.0271 脳 T) and U (39.5276 脳 e) (-24498T), respectively. The limit displacement values of arch and hole are 36.96 mm and 39.53 mm. respectively. The lateral pressure coefficient 位 is determined to be 1.1305 by 12 iterative convergent operations, which satisfies the requirement of convergence accuracy, and the error is 20.95. The objective function f (位) = 31.431.7. (2) the deformation of surrounding rock along the axis of tunnel excavation is decreasing gradually, and there is a linear relationship between extrusion deformation and axial distance. At 位 1.0, the extrusion deformation is approximately linear with the top and bottom preconvergence, but not with the horizontal preconvergence, and when 位 = 1.0, the extrusion deformation is linearly related to the top and bottom preconvergence and the horizontal preconvergence. When 位 1.0, the linear relation between extrusion deformation and horizontal preconvergence is more obvious than that between pre-convergence of roof and bottom. (3) considering that the deformation of weak surrounding rock has occurred before the lining is applied, The test results show that the deformation of surrounding rock before the application of the lining is about 1 / 3 / 2 / 3 of the limit displacement value. When 位 = 1.0, the lining stiffness is chosen as 10.5 GPA, which can provide sufficient support resistance and give full play to the self-supporting capacity of surrounding rock under the reasonable timbering opportunity. (4) there is a linear relationship between extrusion deformation and preconvergent deformation, and preconvergent deformation affects the magnitude of convergence deformation behind the face of the palm. After lining support, the convergence deformation of surrounding rock behind the face of the face is reduced by about 50%, the pre-convergence deformation is reduced by about 25%, and the extrusion deformation is reduced by about 10%. Within 1 m behind the face, the deformation of surrounding rock has changed greatly. Due to the effect of the fixed end effect and the in-situ stress field, the displacement direction of the surrounding rock in front of the face may be opposite. (5) the excavation of double-row tunnel is compared with the excavation of the first hole alone. As a result, the horizontal displacement of the inner side decreases while the horizontal displacement of the outer side increases, and the decrease of the inner side is larger than the increase of the external side. With the increase of 位 value, the vertical displacement of arch and inverted arch increases relatively. When 位 = 0.5, the symmetry effect of displacement increment curve is remarkable. When 位 0.5, the absolute increment of arch displacement corresponding to the same distance is greater than that of inverted arch displacement: when 位 鈮，
本文编号：2366667
[Abstract]:Soft surrounding rock occupies a large proportion in the construction of highway tunnel, and most of them show the characteristics of joint development and high ground stress. At present, the characteristics and deformation mechanism of soft surrounding rock in the construction of small clear distance tunnel are not clear. Therefore, it is of great significance to study the deformation characteristics of soft surrounding rock tunnel. The deformation mechanism of soft surrounding rock tunnel and the balance and stability system of surrounding rock-support structure are analyzed in this paper. According to the new method, the relationship among extrusion deformation, preconvergent deformation and convergent deformation is studied. Based on the field monitoring data, regression analysis is carried out, and the displacement inverse analysis method is used to retrieve the lateral pressure coefficient 位. By using FLAC3D numerical simulation, the deformation characteristics of soft surrounding rock in small clear distance tunnel under different 位 are analyzed. The main conclusions are as follows: (1) regression analysis of field monitoring data is carried out. The optimal temporal curve equations of vault subsidence and horizontal clearance convergence are determined to be U=T/ (0.1154 0.0271 脳 T) and U (39.5276 脳 e) (-24498T), respectively. The limit displacement values of arch and hole are 36.96 mm and 39.53 mm. respectively. The lateral pressure coefficient 位 is determined to be 1.1305 by 12 iterative convergent operations, which satisfies the requirement of convergence accuracy, and the error is 20.95. The objective function f (位) = 31.431.7. (2) the deformation of surrounding rock along the axis of tunnel excavation is decreasing gradually, and there is a linear relationship between extrusion deformation and axial distance. At 位 1.0, the extrusion deformation is approximately linear with the top and bottom preconvergence, but not with the horizontal preconvergence, and when 位 = 1.0, the extrusion deformation is linearly related to the top and bottom preconvergence and the horizontal preconvergence. When 位 1.0, the linear relation between extrusion deformation and horizontal preconvergence is more obvious than that between pre-convergence of roof and bottom. (3) considering that the deformation of weak surrounding rock has occurred before the lining is applied, The test results show that the deformation of surrounding rock before the application of the lining is about 1 / 3 / 2 / 3 of the limit displacement value. When 位 = 1.0, the lining stiffness is chosen as 10.5 GPA, which can provide sufficient support resistance and give full play to the self-supporting capacity of surrounding rock under the reasonable timbering opportunity. (4) there is a linear relationship between extrusion deformation and preconvergent deformation, and preconvergent deformation affects the magnitude of convergence deformation behind the face of the palm. After lining support, the convergence deformation of surrounding rock behind the face of the face is reduced by about 50%, the pre-convergence deformation is reduced by about 25%, and the extrusion deformation is reduced by about 10%. Within 1 m behind the face, the deformation of surrounding rock has changed greatly. Due to the effect of the fixed end effect and the in-situ stress field, the displacement direction of the surrounding rock in front of the face may be opposite. (5) the excavation of double-row tunnel is compared with the excavation of the first hole alone. As a result, the horizontal displacement of the inner side decreases while the horizontal displacement of the outer side increases, and the decrease of the inner side is larger than the increase of the external side. With the increase of 位 value, the vertical displacement of arch and inverted arch increases relatively. When 位 = 0.5, the symmetry effect of displacement increment curve is remarkable. When 位 0.5, the absolute increment of arch displacement corresponding to the same distance is greater than that of inverted arch displacement: when 位 鈮，
本文编号：2366667
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