In recent years, more and more tunnels characterized by large sections, small spacing, and tunnel groups have needed to be expanded. The ground surface settlements in tunnels undergoing in-situ expansion have the following features: the ground surface settlement curve is not asymmetrical across the tunnel centerline and partial mutation exists. Using the Damaoshan in-situ tunnel expansion as an example, this paper analyzes the rules of ground surface settlement induced by the CD construction method. Based on the Peck formula and superposition principle, it presents a simple function expression for predicting the ground surface settlement and demonstrates the adaptability of this method. The results show that the function expression correctly reflects the rules of ground surface settlement induced by in-situ expansion construction and the calculated value agrees well with the test results.%近年来,越来越多的隧道面临改扩建问题,隧道扩建工程往往呈现出大断面、小净距、隧道群等特点,而原位扩建隧道的地表沉降规律也呈现出自身的特性:地表沉降槽曲线沿隧道中心线不对称、存在局部突变值等.对泉厦高速公路大帽山隧道原位扩建工程采用CD工法施工引起的地表沉降实测规律分析,基于Peck公式及叠加原理,提出了适用于隧道原位扩建施工产生的地表沉降的简便预测函数关系式,并验证了函数关系式的适用性.应用研究表明:该函数关系式能正确反映隧道原位扩建施工地表沉降规律,计算值与实测结果较为吻合.研究成果为隧道原位扩建工程地表沉降的预测提供了新的思路与方法.
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