顶管施工引起土体变形的计算方法及应用

Calculation Method and Application of Soil Deformation Induced by Pipe Jacking Construction

顶管施工技术已经广泛用于给排水管道和小直径隧道工程中,同时其施工扰动引起的土体变形问题也越来越受到重视。顶管施工引起周围土体变形的主要因素有:刀盘正面附加推力、顶管机及后续管道与土体之间的摩阻力、注浆压力和土体损失。针对上述影响因素,分析各影响因素单独作用产生的土体变形,然后叠加得出土体总变形计算公式,最后结合港珠澳大桥珠海连接线工程中0#试验管的工程实例分析了其适用性。工程实例分析结果表明:土体损失、注浆压力和顶管机与土体间摩阻力产生的最大土体变形分别为-8.000、2.500和±2.020 mm,这三者是引起土体变形的主要因素;而正面附加推力和后续管道与土体摩阻力产生的最大变形量分别为±0.075和±0.230 mm,影响程度不显著。与Peck公式对比,本文公式除了在最大沉降值处偏差较大以外,其他位置土体变形比Peck公式更接近实测值。

Pipe jacking has been widely applied to water supply and drainage pipelines and small-diameter tunnels; however, the soil deformation induced by pipe jacking may increase the risk of serious construction problems. The main factors causing soil deformation include positive additional thrust of cutter, friction between jacking machine or subsequent pipes and soil, grouting pressure and soil loss. This research focused on and analyzed the soil deformation caused by above factors. The feasibility of deformation formula was proposed by addition of all deformation formula, and was applied to 0# test pipe jacking of Zhuhai connection highway in Hongkong-Zhuhai-Macao bridge project. The results show that the maximum soil deformation induced by soil loss, grouting pressure and frictional resistance between soil and jacking machine is respectively -8.000、2.500 and ±2.020 mm. It also indicates that they are major factors to influence soil deformation. However, the maximum soil deformation induced by positive additional thrust and frictional resistance between soil and subsequent pipes is only ±0.075 and ±0.230 mm respectively, which is non-significant. Except that the deviation is larger at maximum subsidence, the soil deformation calculated value is more close to measured value, compared to Peck formula.