Peck法在武汉地铁隧道地表沉降预测中的适用性分析

Study of Peck equation applied to predict ground settlement induced by subway tunneling work in Wuhan

运用Peck法进行隧道地面沉降预测时,须求解适合于研究区域内特殊地质条件的沉降槽宽度i,该参数随区域特殊地质条件的差异而变化较大,这导致Peck方法的运用具有很强的地域性。运用最小二乘法对武汉地铁第24标段隧道区间的地面横向沉降量实测数据进行了Peck曲线拟合,结果表明:隧道纵向中线埋深与沉降槽宽度i在本区间也大致存在线性关系,即i=kH,且在本区间地层多为黏土、粉质黏土、黏土夹碎石情况下的k值宜取为0.7～0.9之间;当隧道中线埋深为10～15m之间时,约50%的监测断面系数k可取值为0.8,最大可取值为0.95,总体上其平均值约为0.86。运用前人提出的i值经验公式计算结果与拟合值进行比较,所得比值可作为修正系数对不同的经验公式做相应的系数修正,使之能够满足不同地域特殊地质条件下i值的计算需要。运用Peck法进行本区间隧道施工引起的横向地面沉降预测研究是可行的,其沉降槽曲线可以很好地拟合及预测本区间地铁隧道施工引起的地面沉降情况。

When the tunnel ground settlement is predicted, trough width parameter i which is fit for the local geological conditions must be solved. This parameter i will have great variation in different local special geological conditions, which gives the application of Peck method great regional disparity. Based on surveying data of the 24th section of the second line in Wuhan Subway, settlement troughs are polyfited in gaussian curve by least-squares method, the results show that： there is linear relationship between the parameter i and the middle depth of the tunnel H, accordingly, we can consider i = kH, and the value range of k can be 0. 7 -0.9 in the clay, silty clay and gravel clip; and when H is 10 - 15 m, about 50% monitoring sections＇ k can be 0. 8, the maximum can be 0. 95, and the mean value is 0.86. Some multiples can be attained by comparative analyzing results calculated by previous formula and the simulated values, these multiples can be used as the correction coefficients of the previous formula. Generally it is feasible for the correction Peek method to be used in this studying section.