砂层注浆浆液扩散模式与规律试验研究

注浆工程因其隐蔽性和浆液扩散随机性成为控制施工效果的难点,采用模型试验研究可为设计注浆施工工艺提供依据。针对砂层注浆试验中试验结果处理方法和水泥浆液扩散及分布规律开展研究,提出了改进的EDTA二钠滴定法测定水泥含量,利用注浆模型试验装置,改变注浆参数、浆液色彩和开挖方式进行5次模型试验。通过分析注浆后结石体形状,并将试样分块滴定,结合图像变换法处理注浆体研究浆液扩散形态。结果表明:注浆结石体主要由浆液富集区和沿优势路径扩散区组成; 分块滴定检测处理显示浆液由注浆口向外总体呈线性扩散,浆液最大扩散范围随注浆压力、注浆量和水灰比增大而增大,扩散体积与注浆量比值在7.04～8.74之间,可注性随注浆压力和水灰比增大而增大,随注浆量增大而减小; 图像处理显示劈裂作用、潜蚀作用、浆液富集和优势路径等常见浆液扩散模式,并与分块处理相互验证。研究表明所述处理方法在试验中应用效果良好,实际工程中需通过优化注浆工艺避免产生单向大型劈裂通道和潜蚀作用。
It is difficult to control the construction quality of grouting engineering due to the concealment and randomness of slurry diffusion. The model test can provide the basis for the design of grouting construction process. An improved EDTA titration method for the determination of cement content was presented based on the processing method of test results and the diffusion and distribution regularities of cement grouting slurry in sand layer. Five model tests were conducted by changing grouting parameters, slurry color and excavation method using the grouting model test device. The shape of hardened cement stone body was analyzed, and the samples were cut and titrated, and the diffusion morphology of grouting slurry was studied by processing the grouting body using the image transform method. The results indicated that the grouting stone body was mainly composed of slurry enrichment region and the diffusion region formed by limited pathway, and the inhomogeneous distribution of sand particles makes the difference of permeability between different regions. Block processing results showed that the grouting slurry was linearly diffused from the grouting port to outside, and the maximum diffusion range of slurry was between 2 144 cm3 and 3 072 cm3. The ratio of diffusion volume to grouting amount was between 7.04 and 8.74. The grout ability was elevated with the increases in grouting pressure and water cement ratio, and lowered with the increase in grouting amount. The image processing results suggested that the common slurry diffusion mode of grouting slurry included splitting action, latent effect, slurry enrichment and advantage path, and was verified by block processing. The results showed that the proposed method is effective in the experiment, and the one-way large-scale splitting channel and suffusion should be avoided in practical engineering by controlling grouting pressure and arrange the position of grouting holes according to the actual situation, and using phased grouting and multiple grouting process methods