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开发了一种实验室模拟土体注浆的试验装置,能形成完整的试样。通过注浆模拟试验,实现了黏土注浆过程中压密浆泡及劈裂裂隙的自然产生与发展。试验结果表明:在黏土注浆中压滤效应贯穿于整个注浆过程,即在高压的作用下,浆液中自由水被强制滤过黏土,并从泻流口流出,使浆泡及浆脉中的浆液浓度提高。压滤效应随土体渗透性、浆液水灰比及注浆压力的增大而增强,因此在透水性较好的土层中注浆时,必须考虑压滤效应对浆液扩散的影响。浆液水灰比的增大将导致浆泡直径减小,浆脉数量及长度增加,浆脉宽度减小。在给定注浆压力下,随着浆液水灰比的增大,浆液的扩散方式逐渐由以压密为主向以劈裂为主过渡。黏土中劈裂注浆可分为三个阶段:鼓泡压密阶段、第一劈裂面阶段、后续劈裂面阶段,每个劈裂面都产生在阻力最小的面上。通过对原状萧山黏土、清水压密固结黏土及注浆后黏土进行电镜扫描观测分析得知:在压滤效应的作用下,水泥水化反应生成的Ca2+离子会随着滤出液扩散到土体中,导致黏土表面的双电层厚度变薄,使联结更为紧密,从而形成较坚固的团粒结构,使土体强度提高。试验结果对注浆理论研究与工程应用有一定的指导意义。
Developed a laboratory simulation soil grouting test device, can form a complete sample. Through the grouting simulation test, the natural generation and development of pressure grouting and splitting cracks in clay grouting process are realized. The experimental results show that the pressure filtration effect in clay grouting runs through the grouting process. Under the action of high pressure, the free water in the slurry is forced to filter through the clay and flows out from the effusion port to make the pulp and pulp The slurry concentration is increased. The pressure filtration effect increases with soil permeability, slurry water-cement ratio and grouting pressure. Therefore, the effect of pressure filtration on slurry diffusion must be considered when grouting in the well-permeable soil. Increasing the water-cement ratio of the slurry will result in a decrease of the diameter of the slurry, an increase in the number and length of the slurry, and a decrease in the width of the slurry. Under the given grouting pressure, with the increase of the water-cement ratio of the slurry, the diffusion mode of the slurry gradually shifts from the mainly compacting to the splitting-based one. Claw grouting in clay can be divided into three stages: bubbling compaction stage, the first cleavage stage, the subsequent cleavage stage, each cleavage surface are generated in the resistance of the smallest surface. Through the original Xiaoshan clay, clear water consolidation clay and clay after grouting were observed by electron microscopy analysis: under the effect of pressure filtration, cement hydration reaction of Ca2 + ions with the filtrate spread to the soil Body, resulting in thinning of the double-layer thickness of the clay surface, so that the link more closely to form a more solid aggregate structure, so that soil strength. The test results have certain guiding significance for the grouting theory research and engineering application.