Mechanism of seepage control of pulsating grouting in completely weathered granite stratum

For the foundation reinforcement of the completely weathered granite stratum, the traditional grouting technology is limited to the loose structure, and it is difficult to form holes and to increase pressures, which aggravates the difficulty of foundation treatment. The technology of "drilling and grouting simultaneously, pulsating grouting" is put forward. The numerical simulation is carried out under different pulsating pressures and drilling and grouting time. The analysis of stress-strain of the stratum under pulsating pressures is realized. The control mechanism of pulsating grouting reinforcement is revealed by comparing the influence ranges of slurry diffusion of pulsating grouting and stabilized grouting. The field tests are carried put on the clay-cement slurry to verify the rationality of the control parameters. The numerical simulation results show that under the pulsating grouting pressures of 1.5~2.0 MPa and the spacing of holes of 1 m, according to the statistics of the test holes examined by the routine Lugeon tests, 70% of the sections with the permeability is smaller than 2 Lu. By the Lugeon tests on fatigue, the proportion of permeability smaller than 3 Lu is 97%, and the stable permeability is 0.5 ~ 2.4 Lu. The stable permeability by the Lugeon tests on damage is 2 ~ 8.5 Lu. After grouting, the strata integrity is improved to different degrees, and the acoustic wave elevation range is 17.3%~52.5%. The compressive strength of the core samples reaches 7.3 MPa on average, and the stratum uplift is small during grouting. The results of the study have a better application to the completely weathered granite and the similar strata, and provide a reference case for the reinforcement treatment of such strata.