The technology of bio-gronting is a new technique for soft ground improvement. Many researchers have carried out a large number of experiments and study on this topic. However, few studies have been carried out on the...The technology of bio-gronting is a new technique for soft ground improvement. Many researchers have carried out a large number of experiments and study on this topic. However, few studies have been carried out on the dynamic response of solidified sand samples, such reducing liquefaction in sand. To study this characteristic of microbial-strengthened liquefiable sandy foundation, a microorganism formula and grouting scheme is applied. After grouting, the solidified samples are tested via dynamic triaxial testing to examine the cyclic performance of solidified sand samples. The results indicate that the solidified sand samples with various strengths can be obtained to meet different engineering requirements, the use of bacteria solution and nutritive salt is reduced, and solidified time is shortened to 1-2 days. Most importantly, in the study of the dynamic response, it is found that the MICP grouting scheme is effective in improving liquefiable sand characteristic, such as liquefaction resistance.展开更多
Groundwater flow in fractured rock masses,governed by discrete fracture networks(DFNs),critically impacts tunnel engineering safety.This study addresses water-inrush disasters by proposing a DFN-based grouting optimiz...Groundwater flow in fractured rock masses,governed by discrete fracture networks(DFNs),critically impacts tunnel engineering safety.This study addresses water-inrush disasters by proposing a DFN-based grouting optimization method for jointed rock masses(Grades II–IV).The structural grid model is used to evaluate the degree of rock penetration in this area.Permeability coefficients and the radii of permeability ellipses are calculated at 30-degree intervals along the network,enabling comprehensive evaluation.Utilizing the least squares method,seepage ellipses are fitted to determine primary seepage coefficients.In consideration of the most unfavorable scenarios,rock mass seepage coefficients are selected for grouting design calculation.For each grade of surrounding rock mass,assessments are conducted to ascertain the water inflow of unlined tunnels,the water inflow of lined tunnels,and external water pressure on tunnel linings.Tunnel curtain grouting is required when the tunnel water inflow exceeds the design limits.Appropriate parameters for grouting ring thickness and permeability coefficients are selected to fulfill engineering specifications.In cases of excessive external water pressure in tunnel linings and significant inflow of water into the tunnel,it is recommended that grouting and lining operations are carried out after drainage and pressure relief in the tunnel.The DFN methodology enables targeted grouting that reduces water-inrush risks in high-risk zones.展开更多
文摘The technology of bio-gronting is a new technique for soft ground improvement. Many researchers have carried out a large number of experiments and study on this topic. However, few studies have been carried out on the dynamic response of solidified sand samples, such reducing liquefaction in sand. To study this characteristic of microbial-strengthened liquefiable sandy foundation, a microorganism formula and grouting scheme is applied. After grouting, the solidified samples are tested via dynamic triaxial testing to examine the cyclic performance of solidified sand samples. The results indicate that the solidified sand samples with various strengths can be obtained to meet different engineering requirements, the use of bacteria solution and nutritive salt is reduced, and solidified time is shortened to 1-2 days. Most importantly, in the study of the dynamic response, it is found that the MICP grouting scheme is effective in improving liquefiable sand characteristic, such as liquefaction resistance.
基金supported by the Hubei Key Research and Development Program of China(No.2023BCB044)State Key Laboratory of Silicate Materials for Architectures of Wuhan University of Technology of China(No.SYYSJJ2024-09)Hubei Provincial Department of Transportation Applied Basic Research Project of China(No.2023-121-1-21).
文摘Groundwater flow in fractured rock masses,governed by discrete fracture networks(DFNs),critically impacts tunnel engineering safety.This study addresses water-inrush disasters by proposing a DFN-based grouting optimization method for jointed rock masses(Grades II–IV).The structural grid model is used to evaluate the degree of rock penetration in this area.Permeability coefficients and the radii of permeability ellipses are calculated at 30-degree intervals along the network,enabling comprehensive evaluation.Utilizing the least squares method,seepage ellipses are fitted to determine primary seepage coefficients.In consideration of the most unfavorable scenarios,rock mass seepage coefficients are selected for grouting design calculation.For each grade of surrounding rock mass,assessments are conducted to ascertain the water inflow of unlined tunnels,the water inflow of lined tunnels,and external water pressure on tunnel linings.Tunnel curtain grouting is required when the tunnel water inflow exceeds the design limits.Appropriate parameters for grouting ring thickness and permeability coefficients are selected to fulfill engineering specifications.In cases of excessive external water pressure in tunnel linings and significant inflow of water into the tunnel,it is recommended that grouting and lining operations are carried out after drainage and pressure relief in the tunnel.The DFN methodology enables targeted grouting that reduces water-inrush risks in high-risk zones.
