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针对南宁地铁一多变复合地层盾构区间施工期管片上浮问题,对该区间施工期管片上浮实测数据按地层进行分区统计分析,分别得到粉砂–圆砾段、砂层段、泥岩–粉砂质泥岩段及粉质黏土段等典型地层区段上浮量值数学分布特征,而后研究了同步注浆压力、浆液配比及实际出渣量等施工因素对管片上浮的影响规律,并揭示各典型地层段隧道上浮的主要原因;进而在明确了隧道上浮主要影响因素的基础上,利用纵向等效连续梁模型对各典型地层区段管片上浮量值进行预测分析。研究表明:各典型地层区段上浮量值近似服从正态分布,均值主要为30~60 mm,地层特性及隧道埋深对隧道上浮有重要影响,隧道穿越砂层段上浮量值较小,穿越圆砾、泥岩及粉质泥岩等地层较大;同步注浆浆液配比及注浆压力是影响隧道上浮的主要施工因素,另超挖使砂砾石地层受扰失稳也将导致较大上浮,泥岩层中更是因超挖扰动隧道上覆砂砾层,进一步加剧了浆液压力、泥岩膨胀力及“背土”效应对隧道的上挤力等因素对隧道的起浮作用;等效梁模型的上浮量计算结果与现场实测数据具有较好一致性,可利用其与既有现场反馈的实测数据结合预测上浮及检验施工参数的合理性,从而指导盾构施工。
In order to solve the problem of the floating up of the pipe in the construction period of the multi-variable composite stratum of Nanning subway, the measured data of the up-floating pipe in the interval is divided into statistical analysis by strata, and the silt-boulder section, sand section, Silty mudstone and silty clay, and other typical strata of the strata, and then studied the influence law of the grouting pressure on the floatation of the pipe slice by the construction factors such as the synchronous grouting pressure, the slurry ratio and the actual slag discharge amount, etc. The main reason of the tunnel floats in each typical formation is revealed. Based on the clear factors of the tunnel floats, the vertical equivalent continuum beam model is used to predict and predict the float value of the tunnel in every typical formation. The results show that the floating values of the typical stratigraphic sections follow a normal distribution with a mean of 30-60 mm. The stratigraphic characteristics and tunnel depth have an important influence on the tunnel floats. Rough gravel, mudstone and silty mudstone and other strata are larger. The ratio of grouting slurry and grouting pressure of synchronous grouting are the main construction factors that affect the floating of the tunnel. In addition, the overburden makes the gravel stratum disturbed and unstable and will lead to large floating, In the mudstone layer, the overlying gravel layer overrides the disturbed tunnel, further aggravating the influence of the slurry pressure, the expansive force of the mudstone and the “back-to-earth” effect on the tunnel’s uplift force on the tunnel. The equivalent beam The calculation results of the floating amount of the model are in good agreement with the field measured data, which can be combined with the measured data of the existing field feedback to predict the float-up and test the rationality of the construction parameters to guide the shield construction.