An Empirical Evaluation of Ground Settlement due to Shield Tunneling
|關鍵字:||潛盾;隧道;沉陷;寬度參數;地盤漏失;案例分析;Shield;Tunnel;Settlement;Width Parameter;Ground Loss;Case Study|
Based on the field measurement data, this study proposed an empirical procedure to evaluate the surface settlement induced by shield tunneling. Peck (1969) suggested that the surface settlement trough due to tunneling can be approximated by normal distribution curve. The main parameters associated with the function are the trough width parameter (i) and maximum surface settlement (Smax), which can be calculated by the measured ground loss (Gl). This research collected shield tunneling cases in different countries reported from 1971 to 2005. Based on the case studies of width parameter i and ground loss Gl, the following conclusions are drawn. 1.The settlement trough width increases with the increasing tunnel depth. This study classified the tunneling cases into 6 categories according to the soil type encountered and the shield machine used. The relationship between the tunnel depth Z0 and the width parameter i can be approximated by the simple empirical equation . 2.In granular soils, because the compressed-air method and chemical grouting method were commonly adopted at the cutting face of an open shield, the ground disturbance in front of an EPB shield would be greater than that in front of an open shield. As a result, the ground loss Gl and the settlement trough width parameter i due to the EPB shield were larger compared with those due to the open shield. 3.For tunneling with the closed EPB shield, the groundwater intrusion problems are not encountered, and the auxiliary methods were generally not adopted. The absence of additional measurement at the cutting face caused greater ground disturbance during tunneling. 4.The understanding of in-situ ground properties and workmanship of the tunneling crew are important factors to estimate the surface settlement due to tunneling. 5.Based on the 151 tunneling cases, an empirical method was proposed to evaluate the surface settlement trough due to shield tunneling with different shield machines, tunnel depth, tunnel diameter, and soil type.
|Appears in Collections:||Thesis|
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