基于非均质地层模型的围堰注浆防渗数值计算

Heterogeneous stratum model-based numerical calculation of grouting for anti-seepage of cofferdam

基于随机分形理论,以地质勘探资料为基础描述土层物性参数的不确定性和土性参数局部空间差异,构建二维随机地质剖面模型。结合某船闸上游围堰注浆加固与防渗施工实例,以非均质地层模型为渗透介质,基于渗流的基本理论和基本方程,分析了非均质地层的渗流规律。采用有限元理论研究注浆扩散范围,通过分析稳定水头下压力场、浸润线、水流流线、水头等势线以及渗流量的改变探讨了注浆前后渗流场的变化差异,分析和评价了注浆防渗效果。结果显示,注浆前围堰内侧边界单位长度的渗流量为2.82 m^3/d,注浆后围堰内侧边界单位长度的渗流量为0.82 m^3/d,相比注浆之前,渗流量下降了70.92%。可见对该围堰进行注浆防渗处理能够有效地减少水流进入施工场地,形成的防渗帷幕起到了很好的防渗效果。防渗注浆数值计算的渗流量指标满足设计要求,得到了工程的验证。

Based on the random fractal theory,the parameters of the uncertainty of the physical properties of soil layer and the local spatial difference of the parameters of soil property are described in accordance with the relevant geological prospecting data,and then a 2-D stochastic geological profile model is established. Combined with the engineering case of the construction of the grouting for the reinforcement and anti-seepage of the upstream cofferdam of a ship lock,the seepage law of the heterogeneous stratum is analyzed by taking the heterogeneous stratum model as the permeable medium on the basis of the basic theory and basic equations of seepage. Moreover,the grouting diffusion range is studied with the finite element theory,while the difference between the seepage fields before and after grouting is explored and the anti-seepage effect of the grouting is analyzed and evaluated through analyzing the pressure field,infiltration line,water flow line,water-head contours and the change of seepage under steady water-head. The result shows that the seepage per unit length of the cofferdam inner boundary is 2. 82 m^3/d before grouting and it is 0. 28 m^3/d after the grouting; from which the seepage is decreased by 70. 92% if compared with that before the grouting. It is indicated that the anti-seepage grouting for the cofferdam can effectively reduce the water inflow into the construction site and the anti-seepage curtain formed by the grouting has a better anti-seepage effect. The seepage index from the numerical calculation of the anti-seepage grouting can meet the relevant design requirement,thus it is verified through the project concerned.