This paper presents the engineering geological properties and roof control tecnology for a thick coal seam fully-mechanized face mining with hard roof conditions (THC) at the Jinhuagong Coal Mine (JCM), northwest China. The effective support working resistance and appropriate roof control technology are two critical factors for safe and productive mining in the THC. The load-estimate-method (LO...

In this work, a multi-objective optimization on novel insulated roof with solar water heating system at low material cost has been carried out through Taguchi based grey relational analysis technique. The novel roofs have concrete, insulating polyurethane, and a channel of water in a metallic pipe tunneling the chromium block. Chromium block is used to conduct more heat to raise the water to re...

Mines with exceptionally low-strength roof (UCS <3,500 psi and CMRR <40) are much more likely to struggle with roof falls than other mines. Weak roof is a particular problem for many room and pillar mines in the Midwestern and Northern Appalachian coal basins. Traditional roof support techniques are often not up to the challenge at these operations. This paper focuses on two mines, one operatin...

In coal mining hard roofs are one of the main factors causing the occurrence of rock bursts in working panels. To solve this problem, the solid backfill coal mining (SBCM) technique is proposed and used as an effective measure to prevent the rock bursts induced by hard roofs. However, due to the different backfill ratios of working planes, the control effects on hard roofs are quite unique. By ...

This paper presents an overview of observed distresses on low slope roofing systems collected for the Building Envelope Life Cycle Asset Management (BELCAM) project. The data include over 14,000 visible distresses from 600 roofs from seven different climatic regions across Canada. The distresses encountered for built up roofs, modified bituminous roofs and a limited number of single-ply roofing...

W i t h i n the past ten years, the roof rat (Rattus rattus) problem in residential Santa Clara County has developed from an i n s i g n i f i c a n t nuisance to one of major concern. When a considerable number of complaints to the Santa C l a r a County Health Department reported roof rats on telephone cables, a study was made of 29 c i t y blocks to determine the f e a s i b i l i t y of u t...

Perhaps the most significant development in coal mine ground control during the last century was the introduction of roof bolting during the late 1940’s and 1950’s. From an engineering standpoint, roof bolts are inherently more effective than the wood timbers they replaced. Roof bolts promised to dramatically reduce the number of roof fall accidents, which then claimed hundreds of lives each ye...

Youth gangs are on the rise. Today they threaten virtually every major city, many small communities, and even rural areas. The Office of Juvenile Justice and Delinquency Prevention (OJJDP) is committed to helping communities overcome this problem, and an essential first step is understanding the factors that contribute to the growth of youth gangs and the relationship of gang membership to deli...

Cotton rats, roof rats, and rice rats collectively inflict significant damage to sugarcane crops in the Everglades Agricultural Area; however, the relative damage inflicted by each species is unknown. A feeding trial experiment showed that some differences existed in the grams of sugarcane consumed per gram of body mass among species (male cotton rats: 0.39 ± 0.03g; female cotton rats: 0.34 ± 0...

In mine roadway support operations, floor bolting not only played a role in floor heave control, but also in reinforcing roof and its two sides. Correspondingly, bolting of roof and two sides also played a part in floor heave control. To quantify the effect of such bolting, based on roadway support in extremely weak rock, three physical models were produced and tested in laboratory. Through com...