黏土地层大尺寸矩形顶管施工土体沉降及影响规律研究

Study on Soil Settlement and Influence of Large Size Rectangular Pipe Jacking Construction in Clay Stratum

大矩形顶管施工技术被广泛应用于城市地下空间开发中。通过对顶管隧道开挖的顶进过程进行全程模拟,在充分考虑模拟过程的时空性基础上,提出了大尺寸矩形顶管施工的趋真模拟方法,研究了黏土地层大矩形顶管施工中土体扰动规律及注浆压力、土仓压力等敏感因素对土体沉降的影响。研究结果表明:(1)黏土地层的土体变形对注浆压力更为敏感,对土仓压力不敏感,地表变形曲线随着注浆压力的增大由“U”形沉降槽模式向“M”形变形槽模式转化;(2)建议黏土地层上覆土厚度为8~12 m的情况下进行大尺寸矩形顶管施工,建议注浆压力为0.10~0.15 MPa,土仓压力为0.30 MPa,此时不仅可有效减小土体沉降,同时也不会造成过大的隆起;(3)采取“减少注浆压力,增大土仓压力”的双控调节方法,既可控制隧道轴线处不产生较大沉降,也可保证隧道远侧不产生过大隆起。该研究成果对促进黏土地层大尺寸矩形顶管技术的革新具有重要意义,为城市大尺寸矩形顶管施工技术的应用提供了重要的参考。

Large rectangular pipe jacking construction technology has been widely applied in urban underground space development.Based on the simulation of the whole jacking process of pipe jacking tunnel excavation,a true-oriented simulation method of large size rectangular pipe jacking construction is proposed,and the influence of soil disturbance and sensitive factors such as grouting pressure and soil bin pressure on soil settlement is studied.The results show that:(1)The soil deformation value of clay stratum is more sensitive to the grouting pressure,but less sensitive to the soil bin pressure.The surface deformation curve changes from“U”shape to“M”shape with the increase of grouting pressure.(2)It is recommended that when the thickness of soil covering the clay stratum is 8~12 m,the grouting pressure should be maintained at 0.10~0.15 MPa,and the pressure of soil bin should be maintained at 0.30 MPa under the condition of clay stratum,which can effectively reduce the soil settlement and can't cause ex-cessive uplift;(3)The dual-control adjustment method of“reducing the grouting pressure and increasing the soil bin pressure”can not only ensure no significant settlement at the tunnel axis,but also no large bulge at the tunnel far side.The research results are of great significance to promote the innovation of large size rectangular pipe jacking technol-ogy in clay formation,and provide an important reference for the application of large size rectangular pipe jacking construction technology in cities.