南宁地铁盾构隧道施工引起邻近建筑物沉降预测及控制研究

发布时间：2019-05-15 01:44

【摘要】：随着盾构法在地铁建设中的广泛应用,盾构隧道施工对建筑物造成变形沉降的问题受到越来越多的关注。因此,对于建筑物沉降进行预测,以便在设计和施工中采取有效控制沉降的措施,从而防止事故的发生显得非常重要。南宁地铁的建设在如火如荼的进行,盾构法的应用在南宁地铁建设中的应用日趋普遍,因此有必要对此进行深入研究。本文通过监测数据的统计分析及数值模型的计算,研究盾构过程中地表、建筑物沉降在不同地层条件影响下的变化规律以及不同基础型式的建筑物沉降变化规律,分析结果表明:(1)由Peck经验公式拟合得到地表沉降的沉降槽宽度系数、地层损失率的大小排序为:粉土层砂砾石层泥岩及粉砂质泥岩层。由有限元分析得到建筑物沉降曲线沉降槽宽度变化与天然地表沉降规律一致,但同地层条件下其沉降槽更扁平,地层损失率Vl较地表要小。(2)盾构隧道侧穿不同基础型式建筑物的沉降情况,计算得到沉降数值与监测数据水平接近,桩基础深入下部土层与地层结合情况好,沉降值及最大倾斜度约为浅基础50%。盾构对于深基础建筑物影响同时表现在桩身横向变形上,变形最大值发生在靠近隧道第一排桩身中部,桩身变形距离隧道越远数值越小。基于南宁地铁一号线白苍岭～火车站区间建筑物工程实例,根据盾构隧道施工引起的建筑物沉降曲线基本符合Peck经验曲线的特点,结合不同地质条件类别下的建筑物基础埋深、刚度及与隧道的相对位置等因素,对地表沉降Peck公式的地层参数进行修正,得到各地质条件下的建筑物沉降预测公式。并以区间内部分建筑物为实例,将建筑物沉降预测公式计算值与实际监测值进行对比,预测计算值与监测值接近,预测拟合相关系数为82%,误差率在15%左右,结果表明预测方法具有一定的准确性。本文基于实测沉降数据变化规律分析及盾构施工参数的设置,利用灰色关联分析方法分析施工参数与地表、建筑物沉降值的关系,分析得到地表沉降的施工参数对沉降敏感性从大到小依次为:掘进速度、注浆量、气垫仓压力、刀盘扭矩、总推力、开挖仓压力,建筑物沉降的施工参数对沉降敏感性从大到小依次为:注浆量、掘进速度、总推力、气垫仓压力、开挖仓压力、刀盘扭矩。将地表、建筑物沉降监测数据与现行的沉降控制标准对比,发现盾构隧道施工的地质条件为第③类(全断面穿越粉砂岩层)或第⑤类(上部粉砂岩下部泥岩层、上部砂砾石层下部泥岩层)的情况时,地表及建筑物沉降相对较大,部分测值超过了控制值。此外,在盾构隧道全断而穿越砂砾石层的情况时,上部建筑物沉降速率较大,对灾害的控制不利。因此,基于盾构施工参数设置经验,提出采用泥水平衡盾构施工方法穿越此两类地质条件时的施工参数建议值。
[Abstract]:With the wide application of shield method in subway construction, more and more attention has been paid to the deformation and settlement of buildings caused by shield tunnel construction. Therefore, it is very important to predict the settlement of buildings in order to take effective measures to control the settlement in design and construction, so as to prevent the occurrence of accidents. The construction of Nanning subway is in full swing, and the application of shield method in Nanning subway construction is becoming more and more common, so it is necessary to study it deeply. In this paper, through the statistical analysis of monitoring data and the calculation of numerical model, the variation law of surface and building settlement under the influence of different strata conditions and the variation law of building settlement of different foundation types in the process of shield are studied. The results show that: (1) the width coefficient of subsidence trough is obtained by fitting the empirical formula of Peck, and the order of formation loss rate is as follows: silt gravel mudstone layer mudstone and silty mudstone layer. From the finite element analysis, it is found that the width change of the settlement trough in the settlement curve of the building is consistent with the law of natural surface subsidence, but the subsidence trough is flatter under the same formation condition. The formation loss rate Vl is smaller than that of the surface. (2) the settlement of shield tunnel through different foundation buildings is close to the level of monitoring data, and the combination of pile foundation deep into the lower soil layer and strata is good. The settlement value and the maximum inclination are about 50% of the shallow foundation. The influence of shield on the deep foundation building is also manifested in the lateral deformation of the pile body, and the maximum deformation occurs near the middle of the first row of the tunnel, and the farther away the pile body deformation is from the tunnel, the smaller the value is. Based on the example of building engineering in Baicangling ~ Railway Station of Nanning Metro Line 1, the settlement curve of buildings caused by shield tunnel construction basically accords with the characteristics of Peck empirical curve, and combines with the buried depth of building foundation under different geological conditions. The formation parameters of Peck formula for surface subsidence are modified by stiffness and relative position with tunnel, and the prediction formulas of building settlement under various geological conditions are obtained. Taking some buildings in the interval as examples, the calculated values of building settlement prediction formula are compared with the actual monitoring values. The predicted calculated values are close to the monitoring values, the correlation coefficient of prediction fitting is 82%, and the error rate is about 15%. The results show that the prediction method has certain accuracy. Based on the analysis of the variation law of the measured settlement data and the setting of the construction parameters of the shield, this paper analyzes the relationship between the construction parameters and the settlement value of the surface and the building by using the grey relational analysis method. It is found that the sensitivity of construction parameters to settlement is as follows: excavation speed, grouting quantity, air cushion silo pressure, cutter head torque, total thrust, excavation silo pressure. The sensitivity of construction parameters to settlement is as follows: grouting quantity, driving speed, total thrust, air cushion silo pressure, excavation silo pressure and cutter head torque. By comparing the surface and building settlement monitoring data with the current settlement control standards, it is found that the geological conditions of shield tunnel construction are type 3 (full section through silty rock) or type 5 (mudstone in the lower part of upper siltstone). In the case of mudstone strata in the lower part of the upper gravel layer, the settlement of the surface and buildings is relatively large, and some of the measured values exceed the control values. In addition, when the shield tunnel passes through the gravel layer after the shield tunnel is completely broken, the settlement rate of the upper building is large, which is disadvantageous to the disaster control. Therefore, based on the experience of shield construction parameter setting, the suggested value of construction parameters is put forward when the mud-water balance shield construction method passes through these two kinds of geological conditions.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU433;U455.43;U231.3

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