多排孔注浆引起土体变形与孔压规律试验研究

Experimental study of soil deformation and pore pressure caused by multi-row grouting

目前尚未见到软土地区多排孔注浆引起土体变形和超孔压发展规律的系统研究,限制了注浆变形主动控制策略的深化发展。开展了多排孔注浆现场试验,系统研究了单排孔逐孔注浆、多排孔逐排注浆引起土体水平位移和超孔压的变化与叠加规律。研究表明,注浆引起的超孔压随距离衰减迅速,变化规律可用幂函数表达,注浆距离取3 m左右时纠偏效果较好;天津地区超孔压消散较快,有利于注浆控制变形的快速稳定,超孔压随时间的消散规律可用指数函数表达,并提出了计算注浆引起超孔压的经验公式;多排孔逐排注浆时,先行注浆形成的注浆体墙对后续注浆一侧及另一侧土体变形分别具有反力效应和遮挡效应,控制既有建构筑物变形时应遵循“先远后近”逐排注浆的原则,以提高变形控制效果。

There was no systematic study on the development law of soil deformation and excess pore pressure caused by multi row hole grouting in soft soil area to date,which limits the deepening development of active control strategy of grouting deformation.In this study,field tests of multi-row grouting were carried out to systematically examine the variation and superposition law of soil horizontal displacement and excess pore pressure caused by single-row hole-by-hole grouting and multi-row row-by-row grouting.The research shows that the excess pore pressure caused by grouting decreases rapidly with distance,and the variation law can be expressed by a power function.It is recommended that the grouting is about 3 m or closer to the object.At this time,the grouting correction effect is the best.The excess pore pressure caused by grouting dissipated rapidly in Tianjin,which is conducive to the rapid stability of the deformation controlled by grouting.The dissipation law of excess pore pressure over time can be expressed by an exponential function,and an empirical formula for calculating excess pore pressure caused by grouting is put forward.When multiple rows of holes are grouted row by row,the wall formed by prior grouting has reaction force effect and shielding effect on the soil deformation on one side and the other side of the subsequent grouting respectively.When controlling the deformation of existing buildings and structures,the principle of“far before near”row by row grouting shall be followed so as to improve the effect of deformation control.