Abstract
Subsection split grouting technology can effectively improve the grouting efficiency and homogeneity of grouting in a target reinforcement area. It is therefore necessary to clarify the reinforcement mechanism and characteristics of the soft filling medium under the condition of split grouting. A three-dimensional grouting simulation test of segmented split grouting in a soft filling medium was conducted. The distribution characteristics and thicknesses of the grouting veins were obtained under the condition of segmented grouting. The mechanical mechanism of segmented split grouting reinforcement, based on the distribution characteristics of different grouting veins, was revealed. After grouting, a uniaxial compression test and an indoor permeation test were conducted. Based on the method of the region-weighted average, the corresponding permeability coefficient and the elastic modulus of each splitting-compaction region were obtained. The quantitative relationship between the mechanical properties and the impermeability of the soft filling medium before and after grouting was established. The results revealed that three different types of veins were formed as the distance from the grouting holes increased; namely, skeleton veins, cross-grid grouting veins, and parallel dispersed grouting veins. The thicknesses of the grouting veins decreased gradually, whereas the number of grouting veins increased. Moreover, the strikes of the grouting vein exhibited increased randomness. The reinforcement effect of segmental split grouting on soft filling media was mainly confirmed by the skeleton support and compaction. The elastic modulus of the grouting reinforcement solid increased on average by a factor that was greater than 100, and the permeability coefficient decreased on average by a factor that was greater than 40 in the direction of the parallel grouting vein with the most impermeable solid. The research results may be helpful in the investigation of the split grouting reinforcement mechanism under the condition of segmented grouting.
Highlights
Grouting [1,2,3] is increasingly and widely being used in underground engineering, to effectively strengthen soft rock and soil
The grouting reinforcement mechanism and simulation test research of the segmented grouting do not meet the requirements of engineering
There are few discussions on the spatial distribution and the thickness variation of the grouting veins [19], and the reinforcement that is caused by segmental split grouting
Summary
Grouting [1,2,3] is increasingly and widely being used in underground engineering, to effectively strengthen soft rock and soil. Processes 2018, 6, 131 can effectively improve the grouting efficiency when the method of single drilling and multiple grouting is adopted. The grouting reinforcement mechanism and simulation test research of the segmented grouting do not meet the requirements of engineering. Zhang Lianzhen [14] developed a two-dimensional visualization split grouting simulation test device to study the split grouting mechanism of water-rich sands. There are few discussions on the spatial distribution and the thickness variation of the grouting veins [19], and the reinforcement that is caused by segmental split grouting. To obtain the reinforcement characteristics of the soft filling medium under the condition of segmented split grouting, a three-dimensional grouting simulation test system was developed, which could realize segmented split grouting. Based on the methods of the regional weighted average [20], a quantitative relationship between the mechanical properties and the impermeability of the soft filling media before and after grouting was established
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