Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I...Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I.By the approaching, meeting and / or overlapping of different weather systems, when two or more different rainfall systems are getting to conjugate, some MHRPs could be developed, such as: 1) a new cold/warm front or squall line approaches an old front or squall, even when the old one is somewhat decrepit; 2) at the places where two or more synoptic systems with different characteristics are meeting together, such as the meeting of tropical cyclone with the cold airs coming from the mid- and / or high-latitudes, or the low latitude vortex meeting with the westerly trough; 3) at the intersections of some different weather systems, such as the intersection of drylines, squall lines or fronts moving from different directions; and 4) by the overlapping of rainfall parcels produced continuously from a meso-generation centre.II.Resonance Effect and Tibetan Plateau Influence are two reasons why high frequency of heavy and torrential rains arround the meiyu front is discussed also.展开更多
Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of...Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of rooms facing north-south under different weather conditions. Significant warming effect has been identified in terms of lowest and daily-mean indoor temperature in the area of Kunming. The heating amplitude ranges from 7.7C to 10.0C and from 4.6C to 5.8C for the interior part of rooms facing the south and from 4.6C to 7.0C and from 1.3C to 4.4C for the interior part of rooms facing the north, respectively for the two elements. The highest air temperature is higher indoor than outdoor for rooms facing the south, but otherwise is usually true for rooms facing the north. Additional findings point out that buildings not only help maintain relatively warm indoor temperature but delay its variation. The diurnal cycle of temperature indoor is smaller and ranges by 40% ~ 48% for south-facing rooms, and by 20% ~ 30% for north-facing rooms, than outdoor, and the highest temperature is about 2 hours late inside the room than outside. It shows how inertly indoor temperature varies. The work also finds that relative humidity is less indoor in southward rooms than in northward ones and difference is the largest on fine days but the smallest when it is overcast. For the diurnal variation, the indoor relative humidity is large at nighttime with small amplitude but small during daytime with large amplitude. The above-presented results can be served as scientific foundation for more research on climate in low-latitude cities and rational design of urban architectures.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Heavy rains occur in China frequently, which often bring us floods and serious disasters in the summer half-year. The meso-scale heavy rain parcels (MHRP) in the mid-latitude are usually developed in following cases:I.By the approaching, meeting and / or overlapping of different weather systems, when two or more different rainfall systems are getting to conjugate, some MHRPs could be developed, such as: 1) a new cold/warm front or squall line approaches an old front or squall, even when the old one is somewhat decrepit; 2) at the places where two or more synoptic systems with different characteristics are meeting together, such as the meeting of tropical cyclone with the cold airs coming from the mid- and / or high-latitudes, or the low latitude vortex meeting with the westerly trough; 3) at the intersections of some different weather systems, such as the intersection of drylines, squall lines or fronts moving from different directions; and 4) by the overlapping of rainfall parcels produced continuously from a meso-generation centre.II.Resonance Effect and Tibetan Plateau Influence are two reasons why high frequency of heavy and torrential rains arround the meiyu front is discussed also.
文摘Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of rooms facing north-south under different weather conditions. Significant warming effect has been identified in terms of lowest and daily-mean indoor temperature in the area of Kunming. The heating amplitude ranges from 7.7C to 10.0C and from 4.6C to 5.8C for the interior part of rooms facing the south and from 4.6C to 7.0C and from 1.3C to 4.4C for the interior part of rooms facing the north, respectively for the two elements. The highest air temperature is higher indoor than outdoor for rooms facing the south, but otherwise is usually true for rooms facing the north. Additional findings point out that buildings not only help maintain relatively warm indoor temperature but delay its variation. The diurnal cycle of temperature indoor is smaller and ranges by 40% ~ 48% for south-facing rooms, and by 20% ~ 30% for north-facing rooms, than outdoor, and the highest temperature is about 2 hours late inside the room than outside. It shows how inertly indoor temperature varies. The work also finds that relative humidity is less indoor in southward rooms than in northward ones and difference is the largest on fine days but the smallest when it is overcast. For the diurnal variation, the indoor relative humidity is large at nighttime with small amplitude but small during daytime with large amplitude. The above-presented results can be served as scientific foundation for more research on climate in low-latitude cities and rational design of urban architectures.
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.
