基于长沙地铁开挖引起的地面沉降预测分析

发布时间：2018-08-04 19:53

【摘要】：随着我国经济的快速发展,地铁开挖工程已进入大规模建设阶段。然而地铁开挖导致的灾难事故也越来越多,开挖引起的地面沉降在地下工程施工中越来越受到人们的关注。地铁开挖会对周围土体产生扰动,部分土体应力的释放将打破原有土体的应力平衡,施工扰动地层所产生的应力调整及变形传递到地面,引起地基土体性质及其支承条件的改变,导致地面发生不均匀沉降和各种变形,严重时将影响其正常使用甚至出现塌方或隆起破坏。近年来,在国内外很多地铁开挖施工中屡屡出现类似事故,造成重大经济损失和严重社会后果。城市隧道施工引起的地面变形会对环境造成不可避免的负面影响,因此沉降控制是隧道的设计和施工过程中质量管理方面非常重要的一项。本文以长沙地铁二号线西延线望梅区间站地铁开挖工程为背景,首先对地铁开挖引起的横向地表沉降进行研究,在目前众多预测地铁隧道开挖引起地表横向沉降的经验方法中,Peck提出的高斯方程是最简便,也是应用最为广泛的方法。Peck认为施工产生的地面沉降是在不排水的情况下所发生的,所以沉降槽体积应该是等于地层损失的体积。它假设地层损失在整个隧道长度上都均匀分布,隧道施工所产生的地表沉降横向分布近似成一正态分布曲线。由于这一公式的提出是基于有限地区的实测资料,在应用前应先进行基于当地实测资料的验证工作,各地区地质条件的差异性,往往导致Peck公式预测的沉降值与实测数据不相吻合,存在较大的误差。本文根据现场监测数据,采用回归分析法引入两个修正系数,即地表最大沉降修正系数α和沉降槽宽度修正系数β,对Peck公式进行了修正,得出了适用于长沙地铁二号线西延线的Peck公式,并为今后地铁其他线路的修建提供参考依据。同时在收集整理了工程中常用的各种预测长期沉降的数学模型基础上,根据从2012年12月20日至2013年7月15日中的50组沉降数据实测值进行曲线的拟合,计算分析出了其中6种模型预测中的每个参数值,讨论了地铁施工所引起的地面沉降随着时间变化的规律,并比较了实测值和预测值,对比出各个阶段的误差大小,最后选出最适合本项目预测地表长期沉降的预测模型为双曲线模型,研究成果具有一定的理论意义和广阔的应用前景。
[Abstract]:With the rapid development of China's economy, subway excavation project has entered the stage of large-scale construction. However, there are more and more disasters caused by subway excavation, and people pay more and more attention to the ground subsidence caused by excavation. The underground excavation will disturb the surrounding soil, and the release of some soil stress will break the stress balance of the original soil, and the stress adjustment and deformation caused by the construction disturbance will be transmitted to the ground. It causes the change of the properties of the soil and its supporting conditions, which results in uneven settlement and various deformation of the ground, which will affect its normal use and even cause collapse or uplift failure. In recent years, similar accidents have occurred frequently in many subway excavation construction at home and abroad, resulting in significant economic losses and serious social consequences. The ground deformation caused by urban tunnel construction will inevitably have a negative impact on the environment, so settlement control is very important in the design and construction of tunnel quality management. Based on the excavation project of Wangmei section station of West extension Line of Changsha Metro Line 2, this paper firstly studies the lateral surface settlement caused by subway excavation. The Gao Si equation proposed by Peck is the simplest and most widely used method to predict the lateral surface settlement caused by subway tunnel excavation. Peck holds that the ground subsidence caused by construction occurs without drainage. So the settlement tank volume should be equal to the formation loss volume. It assumes that the formation loss is uniformly distributed in the whole tunnel length, and the transverse distribution of surface subsidence generated by tunnel construction is approximately a normal distribution curve. Since the formula is based on the measured data in a limited area, the verification work based on the local measured data should be carried out before application, and the geological conditions of each region are different. The settlement predicted by the Peck formula often does not coincide with the measured data, and there is a large error. Based on the field monitoring data, this paper introduces two correction coefficients by regression analysis, that is, the correction coefficient 伪 of the maximum surface subsidence and the correction coefficient 尾 of the width of the subsidence trough. The Peck formula is modified in this paper. The Peck formula applicable to the west extension of Changsha Metro Line 2 is obtained, and the reference basis for the construction of other subway lines in the future is provided. At the same time, on the basis of collecting and arranging all kinds of mathematical models commonly used in engineering to predict long-term settlement, the curve fitting is carried out according to 50 groups of settlement data from December 20, 2012 to July 15, 2013. Each parameter value in the prediction of six models is calculated and analyzed, and the variation law of ground subsidence caused by subway construction with time is discussed, and the measured and predicted values are compared, and the errors in each stage are compared. Finally, the hyperbolic model is chosen as the most suitable model for predicting the long-term settlement of the land surface. The research results have certain theoretical significance and broad application prospect.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U231.3;P642.26

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