考虑浆土应力耦合作用的劈裂注浆机理分析

Analysis of Split Grouting Mechanism Considering Coupling Effect of Slurry and Soil Stress

浆土应力耦合作用对劈裂注浆浆液扩散规律具有显著影响,砂土劈裂注浆设计应充分考虑这种影响作用.将劈裂注浆视作平面无限域的圆形扩张过程,基于牛顿型本构方程分析了浆液流场变化特征,并将劈裂通道下侧砂层视作半无限空间弹性体,采用弹性力学推导了均布荷载下劈裂通道宽度、浆液压力的分布方程.通过设置不同的浆液黏度、砂土弹性模量参数,深刻揭示了耦合效应下砂土劈裂注浆基本机理.结合郑州地铁某在建工程进行了对比验证.研究结果表明:浆液压力在孔口及远端处急速衰减,而在中间区段呈稳定变化趋势,劈裂通道宽度基本由浆液压力决定,其分布趋势与浆液压力分布趋势相同;浆液黏度、砂土弹性模量是影响劈裂扩散半径的重要因素,黏度和模量均与扩散半径正相关,黏度与劈裂宽度正相关,模量则与劈裂宽度负相关;本文理论计算值与现场开挖实际值偏差12%~15%,基本符合预期要求.

The coupling effect of slurry and soil stress has a significant influence on the slurry diffusion law of split grouting,which should be fully considered in the design phase of split grouting.The split grouting is regarded as a circular expansion process in an infinite plane domain.Based on the Newtonian constitutive equation,variation characteristics of the slurry flow field are analyzed.The sand layer under the splitting channel is regarded as a semi-infinite elastic body.The distribution equations of the splitting channel width and the slurry pressure under the uniform load are derived by elastic mechanics.By setting different slurry viscosity and sand elastic modulus parameters,the basic mechanism of split grouting in sandy soil under coupling effect is revealed.The results show that the slurry pressure decreases rapidly at the orifice and the far end,but changes slowly in the middle section.The width of the splitting channel is basically determined by the slurry pressure,and has a distribution trend the same as that of the slurry pressure.The viscosity of slurry and the elastic modulus of sand are important factors affecting the splitting diffusion radius,and both are positively related to the diffusion radius.The slurry viscosity is positively related to the splitting width,while the modulus is negatively related to the splitting width.Finally,a comparison was made through a project under construction,and it was found that the deviation between the theoretical calculation value and the actual excavation value was 12%−15%,which basically met the expected requirements.