基于傳遞系數(shù)法的隧道洞口順層仰坡加固穩(wěn)定性評價

劉偉

摘 要：順層巖體仰坡地形、地質(zhì)條件復(fù)雜。為預(yù)防工程事故，需要運(yùn)用預(yù)應(yīng)力錨索對隧道洞口仰坡進(jìn)行加固。結(jié)合寶漢高速石門隧道洞口仰坡的研究，在傳遞系數(shù)法理論支撐下，結(jié)合理正分析軟件分析仰坡加錨的必要性，通過錨固加固計算理論得出仰坡的加固方案，運(yùn)用MIDAS數(shù)值模擬軟件對加錨后的順層仰坡進(jìn)行模擬分析。結(jié)果表明：錨索加固后，仰坡坡頂位移速率未超過規(guī)范規(guī)定的位移速率限值。同時，結(jié)合仰坡穩(wěn)定安全系數(shù)的分析得出，穩(wěn)定安全系數(shù)大于規(guī)范規(guī)定的限值，充分證明了仰坡的穩(wěn)定性。

關(guān)鍵詞：傳遞系數(shù)法;順層仰坡;位移速率;穩(wěn)定安全系數(shù)

中圖分類號：U458 文獻(xiàn)標(biāo)識碼：A 文章編號：1003-5168（2019）34-0103-06

Stability Evaluation of Tunnel Portal Reinforcement along the

Front Slope Based on Transfer Coefficient Method

LIU Wei

（China Traffic Tongli Shaanxi Environmental Greening Engineering Co.， Ltd.，Xi’an Shaanxi 710075）

Abstract： The topography and geological conditions of the bedding rock mass slope are complex. To prevent engineering accidents， prestressed anchor cables are needed to reinforce the tunnel entrance slope. The research on the slope of the Baomen Tunnel’s entrance in Baohan Highway was carried out. Under the theory support of transfer coefficient method， and combined with the Lizheng analysis software to analyze the necessity of anchoring the slope， the reinforcement scheme of the slope was obtained by the calculation theory of anchoring reinforcement. The numerical simulation software MIDAS simulated the bedding slope after anchoring. The results show that strengthened by anchor cables， the displacement rate of the bedding slope’s top does not exceed the displacement rate limit by the specification， combined with the stability safety factor analysis of the slope， the stability safety factor is greater than the limit specified in the code， which fully proves the stability of the slope.

Keywords： transfer coefficient method;bedding slope;displacement rate;stability safety factor

隧道洞口段一般埋深較淺、巖體破碎、風(fēng)化劇烈、穩(wěn)定性差。若洞口仰坡傾角與巖層傾角較為接近時，將形成順層仰坡的特殊地質(zhì)構(gòu)造，在施工中易受擾動后失穩(wěn)，出現(xiàn)結(jié)構(gòu)崩塌、順層滑坡等工程事故，嚴(yán)重威脅施工安全[1]。因此，對隧道洞口的順層仰坡穩(wěn)定性進(jìn)行分析，并對其進(jìn)行有效加固具有重大工程意義。

目前，有的學(xué)者主要利用傳遞系數(shù)法中的隱式解進(jìn)行順層仰坡的穩(wěn)定性分析[2];還有學(xué)者將傳遞系數(shù)法作為邊坡主被動錨固方法中穩(wěn)定安全性判別的主要方法[3]。但是，這些理論研究均未考慮隧道開挖對仰坡的穩(wěn)定性的影響。

因此，通過研究邊坡錨固理論，利用傳遞系數(shù)法得出仰坡的加固設(shè)計方案，結(jié)合理正有限元分析軟件（基于傳遞系數(shù)法）的抗滑樁模塊，分析自然狀態(tài)下仰坡穩(wěn)定性，得知仰坡安全系數(shù)低于規(guī)范規(guī)定的限值，安全性較低，必須進(jìn)行加固。……