矩形顶管施工对土层超孔隙水压力的影响研究

Study on In?uence of Rectangular Pipe Jacking on Super Pore Water Pressure in Soil Layer

基于卸荷拱理论,推导出矩形顶管截面等效半径,同时借鉴盾构隧道超孔隙水压力的计算方法,采用修正剑桥模型与应力释放原理,推导出等效管截面周围超孔隙水压力的计算方法,并依据现有研究理论和工程数据推导出超孔隙水压力沿等效管截面法向方向的计算公式。结合工程实际,分析了地铁地下通道矩形顶管施工引起的地层中超孔隙水压力的分布规律。根据分析结果,等效管节水平轴线上部的管周超孔隙水压力小于下部超孔隙水压力,超孔隙水压力沿等效管节外表面法线方向呈凹曲线分布,各方向最大值出现于管周,且超孔隙水压力距离管节较近位置消散较为剧烈,随着距离增大消散速度趋于平缓。

Based on the unloading arch theory,the equivalent radius of rectangular pipe jacking section is deduced.At the same time,referring to the calculation method of super pore water pressure in shield tunnel and using the modified Cambridge model and stress release principle,the calculation method of super pore water pressure along the normal direction of the equivalent pipe section is deduced and its formulas are deduced according to the existing research theory and engineering data.Combining with engineering practice,the distribution law of excess pore water pressure in stratum caused by rectangular pipe jacking construction of underground subway passage is analyzed.According to the analysis results,the super pore water pressure around the pipe at the upper part of the horizontal axis of the equivalent pipe joint is less than that at the lower part,the super pore water pressure along the normal directions of the external surface of the equivalent pipe joint is distributed in a concave curve manner,the maximum value in each direction appears around the pipe and moreover,the excess pore water pressure dissipates violently when it is close to the pipe joint,while the dissipation rates tend to change gently as the distance increases.