矩形顶管施工引起土体分层变形计算方法研究

Study On Calculation Method of Soil Delamination Deformation Caused by Rectangular Pipe Jacking Construction

随着矩形顶管在大城市地下通道建设中的广泛应用,建立矩形顶管施工引起周围地层变形的计算预测模型已成为当前顶管施工必须加以重视的问题。矩形顶管施工引起周围土体变形的主导因素为摩擦力、开挖面附加应力、土体损失,理论分析必须考虑这几个主导因素。针对以上主导因素,提出考虑三者共同作用下的矩形顶管施工地层位移计算方法。用Mindlin位移解对应力作用面积分析顶进过程中开挖面附加应力及摩擦力引起的地层变形;以随机介质理论分析建筑缝隙引起的土体损失产生的地层变形。考虑到各影响因素的相对独立性,将各因素引起的地层变形叠加,从而得到主导因素影响下的地层变形预测模型。通过理论计算,开挖面附加应力、摩擦力主导隆起区地层变形,土体损失主导沉降区地层变形,地层埋深越大此现象越明显。将理论计算值与实测结果对比,两者在变化趋势及变化量上趋于吻合,因此,所提公式可作为类似工程工前地层变形预测计算公式。

With the wide application of rectangular pipe jacking in the construction of underground passage in large cities,the calculation and forecasting model of the deformation of surrounding strata caused by rectangular pipe jacking construction has become a problem which must be paid attention to at present.The main factors that cause the deformation of surrounding soil are the friction force,the additional stress on the end surface,the loss of soil.Theoretical analysis must consider these several dominant factors.In view of the above dominant factors,this paper puts forward the calculation method of formation displacement of rectangular pipe jacking construction under the common action of the three factors.Using Mindlin displacement solution to make integral to Stress-acting surface.The strata deformation caused by the additional stress on the end surface and friction in the advancing process is analyzed.The stochastic medium theory is used to analyze formation deformation caused by soil loss which caused by building a gap.Taking into account the relative independence of the various factors,strata deformation caused by various factors are superposed,and the strata deformation prediction model under the influence of dominant factors is obtained.By theoretical calculation of the additional stress on the end face,the formation deformation in the uplift zone led by the frictional deformation,and the strata deformation in the subsidence area led by the soil loss,this paper find the greater the buried depth the more obvious this phenomenon.Comparing the theoretical calculation with the measured data,both of them tend to coincide with the changing trend and the variation.Therefore,the formula can be used as the prediction calculate the formula of stratum deformation in similar engineering.