土压平衡盾构渗流场解析解及喷涌判别研究

Analytical solution of seepage field and identification of spewing in earth pressure balance shield

考虑土压平衡盾构土舱的二维渗流效应,用解析方法分析了土压平衡盾构的喷涌问题。将土舱渗流场划分成两个区域,利用分离变量法并结合区域间连续条件得到土舱水头显式级数解,将螺旋输送机内流场视为一维渗流,通过土舱与螺旋输送机交界面水流量及水头连续条件得到盾构的渗流场解析解。分别将土舱和螺旋输送机渗流场解析解与数值软件计算结果和试验结果进行对比,结果吻合较好,验证了解的正确性。分析盾构及土层参数对螺旋输送机排土口水流量及水压力的影响,分析结果表明:在螺旋输送机排土口内外水压力差为0的情况下,螺旋输送机内水流量及水压力与刀盘面中心水头近似线性关系;增加螺旋输送机长度和倾角、减小螺旋输送机的直径有利于防止喷涌。基于已有的喷涌研究成果,给出了典型盾构喷涌判别图。通过对盾构喷涌实例进行判别,并与盾构一维解析解的喷涌判别结果进行对比,证明基于本解析解的喷涌判别更为准确。

Considering the two-dimensional seepage effect of chamber of earth pressure balance shield,the spewing problem of earth pressure balance shield is analyzed by using an analytical method.The seepage field of chamber is divided into two regions,and the water head of the chamber is obtained in the form of an explicit hierarchical solution by using the method of separation variables and combining the conditions of continuity between regions.The flow in the screw conveyor is regarded as one-dimensional seepage,and the analytical solution of the seepage field of the shield is obtained based on the water flow and head continuity conditions at the intersection of the chamber and the screw conveyor.The analytical solutions of the seepage field of the chamber and the screw conveyor are compared with the numerical software calculation results and test results respectively,and the results are in good agreement to verify the correctness of the solution.Analyzing the impact of shield and soil parameters on the screw conveyor discharge water flow and water pressure,it is found that a water pressure difference of 0 between the inside and outside of the soil discharge port of the screw conveyor,there is an approximately linear relationship between the screw conveyor water flow and water pressure and water head at cutter surface center;increasing the length of the screw conveyor and inclination angle,and reducing the diameter of the screw conveyor are conducive to prevent spewing.Based on the existing research results of the spewing,a typical shield spewing discriminant map is given.Through discriminating the shield spewing example,and comparing it with the spewing discrimination results of one-dimensional analytical solution of the shield,it is proved that discrimination based on this analytical solution is more accurate.