Study on determining of reinforced concrete false roof strength and design of reinforcement based on reliability theory

Study on efficient mining of the steep incline and fractured ore-bodies in Yongshaba mine of Guizhou Kailin Group shows that ore-body is fractured and difficult to support the roadways in-vein.After research of the actual conditions about the ore-bodies,we have made the initial decision to adopt reconstruction of roof downward sublevel cut-and-fill mining.The men work safely under the false roof supporting the top plate.However,the difficult problem is how to determine the strength of the false roof.In this case,the method based on reliability theory has been put forward.Combined with elastic mechanics and field practice,when practical value of reliable probability is 90 %,the value of the false roof strength has been calculated,and the study shows that stope span greatly influences the false roof strength.With the strength of artificial roof,the reasonable reinforcement design ensures the false roof which can supply the demand of strength under large span and load.

SEMI-TIERED HOUSING FOR LATERITE EARTH SLOPING LANDS-A SUSTAINABLE SOLUTION WITH ALTERNATIVE MATERIALS AND METHODS

Increased demand for affordable housing and the limited availability of flat terrain for its construction are two major problems facing the provision of houses of acceptable quality in many countries around the world.There is limited research integrating the utilization of a stepped approach to sloping terrain with appropriate housing models to minimize slope instability potential.This paper introduces a new semi-tiered housing model where the footprint of the house is located on tiers prepared with short vertical cuts of 1.5-2m.Such vertical cuts are found to be stable with laterite soil which is a commonly available type of soil in the tropics.The excess soil generated from cut material was transformed into cement stabilized rammed earth,which is a cost effective material with low embodied energy.This is an ideal candidate for the construction of retaining walls and foundations,and such applications are demonstrated with adequate details.Further,many other types of sustainable building materials are highlighted with a case study of this housing model in a scheme of 13 housing units in Sri Lanka.The attention to detail required in construction and the applicability of alternative building materials and methods to improve the sustainability of such houses have been discussed in detail.These semi-tiered houses have the potential to address many of the current construction challenges.

Impact of solar reflectivity and infrared emissivity on the thermal performance of metal and concrete roofs in cloudy warmhumid climate

Regions near latitude 0are characterized by warm-humid climate and also by high cloudiness.In these regions,metal roofs has been the most widely used typology.However,in the last decades,the use of heavy concrete roofs has increased significantly.Given its material characteristics,this roof typology offers a higher thermal resistance and thermal mass than a metal roof.Most strategies focus on the use of these characteristics,as well as the use of high reflectivity and emissivity.However,the impact of cloudiness on the effectiveness of these strategies has been little addressed.This research focuses on the impact of reflectivity and emissivity change on the thermal performance of these two roofs in a cloudy warm-humid climate.To achieve this objective,simulations validated with measurements were used.The results show that the efficiency of reflectivity and emissivity is lower in this region compared to other regions.The impact of these properties is further reduced with increasing thermal mass or decreasing thermal transmittance,so the effectiveness of reflectivity and emissivity is minimal on the concrete roof.Finally,this study supports that a metal roof with a reflectivity and emissivity above 0.70 can offer lower daily average temperatures than a concrete roof.