Improvement of a Grouting Flow Measurement Method Based on Laser Ranging Technology

Electromagnetic flowmeters are widely used for slurry flow measurement in grouting engineering, but their accuracy deteriorates under low-flow-rate conditions. To address this limitation, a laser-ranging-based grouting flow measurement method using an average-value algorithm was investigated, and a combined vertical–horizontal baffle configuration was introduced to regulate the slurry free-surface morphology and improve measurement accuracy. Laboratory tests and orthogonal experiments were conducted to evaluate the effects of the slurry water–cement ratio, stirring-shaft rotational speed, and discharge flow rate on measurement performance. Engineering-scale numerical simulations were further performed to clarify the flow-regulation mechanism of the combined baffles. The results showed that the mean relative measurement errors of all nine orthogonal experimental cases were below 4%, with a minimum value of 1.39% obtained at a water–cement ratio of 2:1, a stirring-shaft speed of 40 r/min, and a discharge flow rate of 10 L/min. Accuracy analysis indicated that the influence of the investigated factors followed the order of discharge flow rate > water–cement ratio > stirring-shaft rotational speed, with discharge flow rate being the dominant factor. The combined baffles improved measurement accuracy over a range of slurry concentrations and discharge conditions, with a maximum improvement of 6.88% at a discharge flow rate of 1 L/min. The numerical results further showed that the combined baffles disrupted the dominant tangential flow, suppressed central-vortex formation, and flattened the slurry free surface. Meanwhile, the horizontal baffles reduced the upward transmission of disturbances from the lower rotating region, thereby limiting excessive free-surface fluctuations. These findings demonstrate the potential of the proposed baffle-assisted laser-ranging method for accurate slurry flow measurement, particularly under low-flow-rate grouting conditions.