Chunhui Feng

Bio: Chunhui Feng is an academic researcher from Beijing University of Technology. The author has contributed to research in topics: Separator (oil production) & Water supply. The author has an hindex of 1, co-authored 2 publications receiving 5 citations.

Development and assessment of a water pressure reduction system for lining invert of underwater tunnels

Abstract: To efficiently reduce the secondary lining external water pressure on underwater tunnels, the feasibility of a novel bottom-up drainage and water pressure reduction system for reducing has been val...

Tunnel water pressure distribution rule model test device

Abstract: The invention discloses a tunnel water pressure distribution rule model test device, and more specifically provides a model test device used for study of tunnel lining bearing aperture water pressuredistribution rules under different underground water flow states. The model test device comprises a test box, a water supply system, and a water discharge system; the test box comprises a box body, atunnel lining, and water inlets and outlets; the water supply system comprises a water collecting tank, a variable frequency water pump, and a water separator; the water discharge system comprises a water discharge blind tube and a gutter; the water inlets and outlets are arranged on the two sides of a tunnel; the water inlets are arranged at equal intervals; the external sides of the water inletsare connected with water valves through welding, and the water valves are used for controlling water inlet flow amount. The tunnel lining is used for stimulating practical tunnel lining; the water collecting tank is used for recycling underground water discharged by the tunnel water discharge system, and providing the test box with water source; the variable frequency water pump is arranged in the water collecting tank, and is used for conveying underground water to the water separator, and the water separator is used for pumping underground water into the test box water outlets.

Curtain grouting experiment in a dam foundation: case study with the main focus on the Lugeon and grout take tests

Abstract: The Baihetan super-high arch dam is constructed under complicated geological conditions, including large-scale columnar jointed basalt (CJB) with closely spaced joints and multiple interlayer and intralayer shear belts at the lower part of dam base, which may increase a risk of seepage in adjacent dam foundations. Therefore, curtain grouting is used to reduce the permeability of dam foundations. Lugeon and grouting field tests and geological exploration were carried out to investigate curtain grouting characteristics of the dam foundation. The findings were as follows: (1) the permeability coefficient of the first type of CJB and breccia lava without unloading is 2 × 10−5 ~ 5 × 10−5 cm/s; that of the second type of CJB without unloading is 2.5 × 10−5 ~ 5 × 10−5 cm/s; and that of the unloaded third type of massive basalt is 1 × 10−5 ~ 3 × 10−5 cm/s. (2) The rock core shows that the slurry caused repeated splitting of the rock mass and widened the cracks of the rock mass, which resulted in plastic deformation of the rock mass. The P ~ Q curve of the five-point Lugeon test shows that the curve shape is turbulent and that the maximum Lugeon value appears at the highest pressure. (3) The phenomenon of low-permeability conditions with a large grout take can be frequently observed. The proportion of the hole stages with a water permeability less than 1 LU and grout take greater than 50 kg/m ranges from 12.5 to 37.5%. The proportion of holes with permeability greater than 10 Lu and grout take greater than 50 kg/m is 0 to 12.5%. The findings from this case study can provide a reference for engineering construction.

Experimental Study on the Effect of Hydraulic Deterioration of Different Drainage Systems on Lining Water Pressure

Abstract: With the increasing operation time of tunnels, the drainage system cannot fulfil its proper function as a result of the deterioration of traditional waterproof and drainage systems (TWDS), such as the blockage of drainage blind pipes and the failure of drainage boards. Therefore, the lining bears a high water pressure and even causes disasters such as tunnel leakage and lining cracking. An effective solution to mitigate these issues is to adjust the tunnel drainage scheme. In view of this, a composite waterproof and drainage system (CWDS) is proposed in this paper. To verify the effectiveness of the proposed system, a series of model experiments were conducted to study the change law of the seepage field of two drainage systems under different blockage conditions. The study results showed that longitudinal blind pipe blockage caused a more significant increase in water pressure than circular blind pipe blockage. In the case of blind pipe blockage, the water pressure of the TWDS tunnels rise rapidly, while the CWDS tunnels could effectively drain and reduce pressure.

Study on the Annual Reduction Rate of Vehicle Emission Factors for Carbon Monoxide: A Case Study of Urban Road Tunnels in Shenzhen, China

Abstract: Environmental pollution and energy conservation in urban tunnels have become important issues that affect the scientific design and sustainable development of urban tunnels. The carbon monoxide (CO) concentration in urban road tunnels is regarded as a direct reflection and a useful tracer of the intensity of anthropogenic transportation activities. Previous studies in recent years have paid more attention to pollutant emission factors, but less to the calculation parameters of ventilation design for tunnels. This paper aims to study a reasonable annual reduction rate of CO base emission factors. Therefore, a detailed field measurement was carried out in the four typical urban road tunnels, Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel in Shenzhen, China, from March 29 to September 16, 2014. Measurement results showed that the traffic flow of the four urban tunnels had been approaching the design value, or even beyond the limit. The average daily air velocities in the four tunnels were all within 5 m/s, whereas the maximum air velocity had exceeded the limit of 10 m/s. The CO concentrations in Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel were 17 ppm, 7 ppm, 39 ppm, and 8 ppm, respectively. Moreover, it was found that the average CO emission factors of Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha Tunnel were 1.075 g/(km·veh), 1.245 g/(km·veh), 4.154 g/(km·veh), and 1.739 g/(km·veh), respectively. Based on the statistical data, the CO emission factors of mixed traffic and passenger cars decrease by an average of 16.4% and 33.3%, respectively, per year through the regression method and by an average of 17.4% and 29.0%, respectively, per year through the extremum method. Finally, when considering the safety factor of 20%, it is more reasonable for the CO base emission to adopt 4% as an annual reduction rate for ventilation design in urban tunnels.