基于D-P修正准则的扩孔理论在黄土劈裂注浆中的应用分析

基于塑性力学与大变形理论,考虑Drucker-Prager修正准则圆孔扩张问题,建立黄土劈裂注浆压力分析模型.在弹性区和塑性区分别采用小变形理论和大变形理论,推导出劈裂注浆浆泡周围弹性区及塑性区土体应力场、位移场的理论解,研究塑性区半径、起劈注浆压力的解析解,以工程算例进行论证.结果表明,基于考虑D-P修正准则的圆孔扩张理论模型,径向应力与环向应力随r_u/r_P的增大呈现非线性递减关系;不排水条件下随着土体材料参数(c、φ、E、ν)的增大,浆液竖向及水平向劈裂土体时的劈裂压力呈非线性增大趋势;经对比分析发现,理论计算值在514.2～693.7 kPa,与实测值430～780 kPa比较接近,说明了理论的分析方法在黄土地区劈裂注浆工程中具有一定的实用价值.

Application of cavity expansion theory based on D-P revised criterion in fracturing grouting of loess

Based on the theory of plastic mechanics and large deformation, considering the hole expansion problem of Drucker-Prager modified criterion, an analysis model of loess splitting grouting pressure is established. The small deformation theory is adopted in the elastic zone and the large deformation theory is adopted in the plastic zone. The theoretical solutions of the stress field and displacement field of the elastic and plastic zone around the grouting bubble are derived. The analytical solutions of the radius of the plastic zone and the starting grouting pressure are studied. Finally, the engineering example is used to demonstrate. The results show that Based on the theoretical model of circular cavity expansion considering D-P correction criterion, the radial stress and circumferential stress show a nonlinear decreasing relationship with the increase of r_u/r_P. Under undrained condition, with the increase of soil material parameters (c、φ、E、ν), the splitting pressure increases nonlinearly when the slurry splits the soil vertically and horizontally. The theoretical calculation value is 514.2~693.7 kPa, which is close to the measured value of 430~780 kPa. It shows that the theoretical analysis method has a certain practical value in the splitting grouting project in loess area.