【摘要】：隧洞開挖過程中,應(yīng)力重分布造成硐室周圍巖體的剛度、強(qiáng)度參數(shù)發(fā)生變化,影響巖體變形和強(qiáng)度特征,直接關(guān)系到圍巖體的穩(wěn)定性。本文綜合運(yùn)用室內(nèi)試驗、理論分析、數(shù)值模擬及現(xiàn)場試驗等方法,對圍巖體力學(xué)參數(shù)的演化規(guī)律,進(jìn)行了系統(tǒng)的研究,主要包括：(1)基于常規(guī)三軸壓縮試驗(圍壓：5-40MPa),研究了不同圍壓條件下砂巖、花崗巖變形、強(qiáng)度、破壞形式等特征。通過分析裂隙初始應(yīng)力、裂隙貫通應(yīng)力、峰值應(yīng)力與圍壓的關(guān)系,得出砂巖、花崗巖特征應(yīng)力對應(yīng)的強(qiáng)度參數(shù),研究了巖石壓縮破壞前強(qiáng)度參數(shù)的變化規(guī)律。(2)在Mohr-Coulomb準(zhǔn)則框架下,以塑性剪切應(yīng)變?yōu)閮?nèi)變量,通過試驗獲取了砂巖、花崗巖強(qiáng)度參數(shù)的演化規(guī)律。Weibull函數(shù)和Lognormal函數(shù)可以較好地描述強(qiáng)度參數(shù)的初值、殘值和演化規(guī)律。內(nèi)摩擦角表現(xiàn)出先強(qiáng)化后弱化的特點。在FLAC3D內(nèi)置應(yīng)變軟化模型中調(diào)用強(qiáng)度參數(shù),模擬巖石三軸壓縮過程,模擬的應(yīng)力應(yīng)變曲線表現(xiàn)出峰前硬化、峰后軟化特征,峰值強(qiáng)度、殘余強(qiáng)度與試驗值平均相對誤差分別為4.14%和11.42%。(3)工程開挖時,圍巖體剛度會因為卸荷和沖擊擾動而劣化。通過在擾動巖體中鉆芯取樣及試驗測定,分析彈性模量值在圍巖中的分布狀態(tài)�；跀_動程度和擾動范圍雙重因素,提出孔深-彈性模量法,以歸一化和積分形式給出圍巖擾動系數(shù)的計算公式,評價擾動巖體彈性模量的劣化程度。將彈性模量法分析的擾動系數(shù),與傳統(tǒng)聲波法測定值相比較,驗證了彈性模量劣化評價方法的合理性,并對擾動巖體彈性模量進(jìn)行修正(4)基于圍巖體強(qiáng)度演化模型和剛度劣化研究,考慮圍壓和剪脹角等因素,對圓形隧洞平面問題的彈塑性解析解進(jìn)行了修正。以集安引水隧洞圓形主洞為例,采用修正后的隧洞彈塑性解析程序,研究了支護(hù)力對圍巖塑性區(qū)范圍和變形的作用,得出塑性區(qū)半徑和支護(hù)力呈指數(shù)關(guān)系。同時發(fā)現(xiàn)隨著巖體彈性模量劣化程度加劇,塑性區(qū)范圍近似線性擴(kuò)大,圍巖收斂位移近似指數(shù)型增長,彈性模量劣化是洞壁附近圍巖變形大的重要原因。將修正前后的彈塑性解析值進(jìn)行了對比。并將修正前后計算的位移值與實測值相比較,修正計算值與實測值更為接近,驗證了圍巖體剛度強(qiáng)度演化規(guī)律的合理性。(5)另外,基于圍巖體剛度強(qiáng)度演化規(guī)律,數(shù)值模擬了集安引水隧洞城門形支洞掌子面推進(jìn)過程中圍巖位移場、應(yīng)力場、塑性區(qū)和彈性應(yīng)變能的演化規(guī)律。開挖全過程主應(yīng)力改變、位移釋放主要集中在掌子面前后[-D,D](D為隧洞直徑)區(qū)間。模擬計算的位移值與后期監(jiān)測數(shù)據(jù)相對誤差8.63%,驗證了圍巖體力學(xué)參數(shù)演化規(guī)律的準(zhǔn)確性。
[Abstract]:During the tunnel excavation, the stress redistribution causes the change of the stiffness and strength parameters of the surrounding rock mass, which affects the deformation and strength characteristics of the rock mass and directly relates to the stability of the surrounding rock mass. In this paper, the evolution law of surrounding rock mechanics parameters is systematically studied by means of indoor test, theoretical analysis, numerical simulation and field test. The main contents are as follows: (1) based on the conventional triaxial compression test (confining pressure: 5-40MPa), the characteristics of sandstone, granite deformation, strength and failure form under different confining pressures are studied. By analyzing the relationship between initial stress, fracture through stress, peak stress and confining pressure, the strength parameters corresponding to the characteristic stress of sandstone and granite are obtained. The variation of strength parameters before compression failure of rock is studied. (2) under the framework of Mohr-Coulomb criterion, the sandstone is obtained by experiments with plastic shear strain as internal variable. Weibull function and Lognormal function can describe the initial value, residual value and evolution law of strength parameter. The angle of internal friction shows the characteristic of strengthening first and then weakening. The strength parameters were transferred into the FLAC3D strain softening model to simulate the triaxial compression process of rock. The stress-strain curves showed pre-peak hardening, post-peak softening and peak strength. The average relative error between residual strength and test value is 4.14% and 11.42% respectively. (3) during excavation, the stiffness of surrounding rock body will be degraded by unloading and impact disturbance. The distribution of elastic modulus in surrounding rock is analyzed by sampling and testing the core in disturbed rock mass. Based on the dual factors of disturbance degree and disturbance range, the method of pore depth and elastic modulus is put forward, and the calculation formula of disturbance coefficient of surrounding rock mass is given in the form of normalization and integral to evaluate the deterioration degree of elastic modulus of disturbed rock mass. Comparing the perturbation coefficient of the elastic modulus method with the traditional acoustic wave method, the rationality of the method for evaluating the degradation of elastic modulus is verified. The elastic modulus of disturbed rock mass is modified. (4) based on the strength evolution model of surrounding rock mass and the study of stiffness deterioration, the elastic-plastic analytical solution of the plane problem of circular tunnel is modified by taking into account the factors of confining pressure and shear-expansion angle. Taking the circular main tunnel of Ji'an diversion tunnel as an example, the effect of supporting force on the range and deformation of surrounding rock plastic zone is studied by using the modified elastic-plastic analytical program, and the exponential relationship between the radius of plastic zone and the supporting force is obtained. At the same time, it is found that with the deterioration of elastic modulus of rock mass increasing, the range of plastic zone approximately expands linearly, the convergent displacement of surrounding rock increases approximately exponentially, and the deterioration of elastic modulus is an important reason for the large deformation of surrounding rock near the wall of the cave. The elastoplastic analytical values before and after the correction are compared. Compared with the measured values, the calculated displacement values are closer to the measured values, which verifies the rationality of the evolution law of the stiffness and strength of the surrounding rock mass. (5) in addition, based on the evolution law of the stiffness and strength of the surrounding rock mass, The evolution of displacement field, stress field, plastic zone and elastic strain energy of surrounding rock during the advance of the face of the gate branch tunnel in Ji'an diversion tunnel are numerically simulated. During the whole process of excavation, the main stress changes, and the displacement release is mainly in the section before and after the face of the palm [-DU D] (D is the diameter of the tunnel). The relative error between the calculated displacement value and the later monitoring data is 8.63, which verifies the accuracy of the evolution law of the surrounding rock physical parameters.
【學(xué)位授予單位】：北京科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TV554

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 鄧楚鍵;鄭穎人;王凱;高飛;;有關(guān)巖土材料剪脹的討論[J];巖土工程學(xué)報;2009年07期

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本文編號：2308103