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Abstract: The effective control of gas emissions from longwall faces and gob areas in the coal mining industry in China has become increasingly important. Drilling underground gas drainage holes from a surface is an effective way to release gas. Once a coal seam is extracted, the rock strata above a gob subside and move, after which the gas drainage borehole and casing become damaged due to state changes in the rock. In this paper, we perform a deformation and failure analysis of a surface venthole casing using the numerical simulation method. The numerical investigation is carried out on the casing under compression, tension, and shear conditions. The general factors that affect casing failure are discussed, and basic failure modes are summarized. The experimental casing of the surface venthole at Cheng Zhuang Colliery (CZC) is also analyzed by numerical simulation. The actual deformation and failure of the casing are examined using on-site monitoring data, to which the numerical simulation results are then compared. We deduce that the tensile and shear failures occur at the lower part of the casing or at the bedding plane separation. Monitoring must be focused on these areas, and protective measures should be used. The numerical simulation model is simplified given various restrictions. The integration of numerical simulation and monitoring technology can serve as an efficient method for the quantitative analysis of failure on surface venthole casings. The research concepts presented in this paper and the rules deduced are useful references. [Copyright &y& Elsevier]

Abstract: This paper presents an analytical framework to estimate the Total Allowable Area for Coastal Reclamation (TAACR) to provide scientific support for the implementation of a coastal reclamation restriction mechanism. The logic of the framework is to maximize the net benefits of coastal reclamation subject to a set of constraints. Various benefits and costs, including the ecological and environmental costs of coastal reclamation, are systematically quantified in the framework. Model simulations are developed using data from Tongan Bay of Xiamen. The results suggest that the TAACR in Tongan Bay is 5.67 km2, and the area of the Bay should be maintained at least at 87.52 km2. [Copyright &y& Elsevier]

Abstract: Water footprint is an indicator showing the consumption impact on environment with water equivalent, which allows a detailed quantification of water use directly and indirectly in sectors for the domestic and abroad final consumption. This paper presents a framework of calculating national water footprint (NWF) with input–output method on China 2002. The results indicated that the NWF of China was 381m3/capyr in 2002. A new indicator termed as national water footprint intensity (NWFI) is also derived from NWF to evaluate the water consumption intensities of different sectors. Then the evaluation of virtual water trade in sectors is followed, the results of which give a detailed quantification of net virtual water import of sectors, verifying that China is a net virtual water exporter concerning the whole national sectors, which is different from the previous studies. Finally, it is suggested that the sectors with high NWFI and volume of net virtual water export should be regarded as the priority of Chinese water-saving strategy. [Copyright &y& Elsevier]

• Shield tunnel lining damage induced by soil-water inrush is studied. • Numerical simulation matches with field results reasonably. • Strength reduction method have been applied for the consideration of soil loss. • Lessons learned from this incident have been presented. This paper reports a case study on shield tunnel lining damage induced by soil-water inrush occurred in Tianjin Metro Line 1, China through both field monitoring and numerical simulation. This incident was triggered by the non-watertight boring work of thru holes adjacent to the cross passage between the twin tunnels. Under high hydraulic gradient, the seepage-prone weak zone was formed and extended, then the outburst of soil-water slurry was occurred. Measures including plugging engineering cotton, injecting quick-setting cement and welding partition plate of steel segments, had been taken but in vain. The outburst of soil-water slurry induced soil movement around the cross passage, thus leading to the damage of tunnel lining and ground surface settlement. After sealing the water ingress holes, stabilization methods including surface grouting and inside tunnel back grouting were applied. The mechanisms of segment lining damage and the effectiveness of stabilization are investigated through both numerical simulation and field monitoring data analysis. Lessons learned from this incident have been discussed, thus providing reference for potential shield tunnelling under similar engineering conditions. [ABSTRACT FROM AUTHOR]