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为了维持砂土地层盾构隧道开挖面的稳定性,以楔形体模型2种常用的面积等效方法为出发点,对开挖面支护压力计算公式进行推导,同时结合现有楔形体模型与Takano 1g模型试验结果从砂土盾构开挖面破坏区外形的角度改进楔形体计算模型,在考虑松动土压力的情况下提出盾构开挖面主动极限支护压力的计算公式并简化。将Chambon离心模型试验结果与楔形体支护压力计算结果进行对比,并依托西安盾构隧道工程土舱压力监测数据对新公式进行工程应用分析。研究结果表明:采用第1种面积等效方法时的楔形体模型计算结果更为精确,不同模型计算结果出现差异的主要原因来自于楔形体竖直侧面摩擦力的影响,同时提出1.5倍所提简化公式的计算值作为上部土舱压力设定的建议值。
In order to maintain the stability of excavation surface of shield tunnel in sand formation, two commonly used equivalent area methods of wedge model are taken as a starting point to deduce the formula of supporting pressure of excavation face. Combined with the existing wedge model and Takano 1g model test results improve the wedge calculation model from the perspective of the shape of the excavation surface damage zone of sand shield, and put forward the calculation formula of the active limit support pressure of shield tunneling surface considering the loose earth pressure. Comparing the result of Chambon centrifuge model test with that of wedge supporting pressure, and applying the data of XCMG tunneling pressure monitoring data to engineering analysis of the new formula. The results show that the calculation results of the wedge model with the first area equivalent method are more accurate. The main causes of the difference between the calculated results of the different models are the frictional forces of the vertical side of the wedge, The calculated value of the simplified formula serves as the recommended value for the pressure setting of the upper soil compartment.