堤坝脉动注浆浆液扩散机制及应用研究

基于脉动注浆泵可输出低频周期性脉冲压力的特点，结合可控性黏土固化浆液，提出了一种可用于堤坝防渗加固的新方法。通过进行原型试验验证了该方法的可行性，考虑钻孔扰动和脉动低频重复压力对地层渗透特性的影响，推导了黏土固化浆液脉动扩散方程，运用多场耦合软件COMSOL探讨了脉动压力下黏土固化浆液扩散的机制，最后将研究成果成功应用于南水北调中线鹤壁段引水渠道边坡帷幕注浆工程。研究结果表明：黏土固化浆液脉动控制注浆技术可显著提高地层连续性和整体性，结石体28 d强度大于2 MPa，渗透系数可降至10?5 cm/s左右，浆液在注浆孔附近与土体胶结成块，邻近注浆孔浆脉交错搭接，整体表现为空间立体网状包裹结构的防渗墙体；对数值模拟和现场试验结果进行综合分析，堤坝脉动注浆时间应控制在1 800～2 400 s之间，合理的脉动注浆压力在0.2～2 MPa之间，脉动持续时间宜调至4～8 s，脉动间隔时间宜调至2～6 s，这样有利于保证堤坝脉动注浆工程达到最优的防渗加固效果；工程实践的渠道边坡连续性、整体性得到了改善，注浆止水加固效果显著，检查孔渗透系数降至10?5 cm/s，所取芯样完整，芯样最长可达40 cm。

Research on the diffusion mechanism and application of pulsate grouting in embankment and dam

Based on the characteristics of low frequency periodic pulse pressure, a new method was proposed for seepage control and reinforcement of a dam. A prototype test of a manmade homogeneous embankment demonstrated that the method, considering drilling disturbances and repetitive pulsating pressure on the permeability of strata, was feasible. The clay-cement slurry pulsation diffusion equation was determined using the multi-coupling software COMSOL to investigate the mechanism of fluctuating pressure under the clay-cement slurry diffusion. Finally, this research was successfully applied to the Hebi section of the middle route water diversion channel along the grout curtain slope. The results showed that the 28-day strength of stone was greater than 2 MPa and the permeability coefficient was reduced to approximately 10?5 cm/s, demonstrating that the clay-cement slurry pulsation control grouting technology can significantly improve the stratigraphic continuity. Observations were made on the slurry in the grouting hole near the soil and cement block, the adjacent grouting hole slurry vein staggered lap joint, and the overall performance of the impervious wall space of the three-dimensional structure. Based on a comprehensive analysis of the numerical simulation and the field test results, the dam grouting time fluctuation should remain between 1 800 s and 2 400 s, a reasonable grouting pressure pulsation should be between 0.2 MPa and 2 MPa, the pulse duration should be between 4 s and 8 s, and the pulse interval time should be adjusted to between 2 s and 6 s. These values ensure that the seepage and the reinforcement of the dam grouting remain in optimal engineering ranges. The channel slope continuity and integrity were improved, and significant improvement was noted for grout reinforcement sealing. The coefficient was reduced to 10?5 cm/s, and the core sample remained as a whole with the length up to 40 cm.