| China is a country of huge energy consumption and coal is a major driven power. Some date indicates that, coal output in China in 2012 exceeded 3.2 billion tons and gangue output in 2012 is predicted to exceeded 0.3 billion tons. However, development of gangue application in China develops pretty slowly. Now, it comprehensive application rate is low and most of them have not been processed. By far, China has gangue mine lots of about 1600, accumulation mass of gangue has exceeded 3.5 billion tons with coverage of 3.5 billion mu. Gangue has become one of those industrial wastes of huge output, land coverage and deposit volume. In this paper, based on cheap cement-flyash-gravel pile (CFG pile), gangue is used to replace gravel as coarse aggregate and by optimizing ratio to reach a pile of certain strength-coal gangue CFG pile.This paper made 16 briquette combined by 4 kinds of cement-mixed ratio 10%,12%,14%,16% and 4 replacing rate of gangue,0%,30%,60%,100%, based on which, the following coal gangue CFG model: â‘ coal gangue CFG model piles of 4 ratio which is when cement-mixed ratio is 12%, replacing rate is 100%,60%, 30%,0%;â‘¡coal gangue CFG model piles of 4 ratio which is when cement-mixed ratio is 14%, replacing rate is 100%,60%,30%,0%;â‘¢coal gangue CFG model piles of 4 ratio which is when cement-mixed ratio is 16%, replacing rate is 100%, 60%,30%,0%; the number of model piles is twelve.According to compression test of gangue concrete, impact of cement-mixed ratio, age, replacing rate of gangue on compressive strength of gangue and its change rule. CFG model in this paper is end bearing pile. Different bearing capacity limit of coal gangue CFG pile of mixing ratio is gained via coal gangue CFG model static bearing test. Stress distribution, failure mode of piles is studied and analyzed by stress-stress curve and load-settlement curve of model piles. Its study result is as follows:(1) Gangue concrete compressive strength has a logarithmic function with age and logarithmic function can be used to fit. When cement-mixed ratio locates within the range of 10-14%, strength increase rate of gangue concrete is huge. When cement-mixed ratio is larger than 14%, increase ratio of gangue concrete strength is decreased significantly. Compressive strength of gangue concrete has relationship of quadratic equation of one variable with cement-mixed ratio. Compressive strength of gangue concrete at Yanbian area decreases following increase of gangue replacing ratio. C3 is considered the best ration combination taking into consideration of safety factor and economic factor with concrete:coal ash:water:gravel:self-ignition gangue= 247.8:106.2:177:780:468.4:702.6.(2) Following the increase of replacing ratio of gangue, limit bearing of model pile is lowering. At the same vertical load, increase ratio of sedimentation value of model pile is increasing. The damage is at the upper 1/3 of the pile. Damage power of coal gangue CFG pile is the similar to that of common CFG piles. In the bearing-strain diagram, load shared at the top of pile is huge. At the top of the pile, strain increase ratio of strain testing point grows at a significantly faster speed than that of other testing points.(3) Through the 12 CFG limit model of coal gangue pile static load test of bearing capacity, puts forward the calculation formula of the bearing capacity of the reference model of CFG pile of coal gangue: Nuk= 0.361fouAp+86.107, R2=0.8293,(4) Three prediction test of grey theories are applied to limit predict load of single coal gangue CFG model pile. Prediction value is analyzed and managed to get the new iteration GM (1,1) model which has higher prediction precision for single pile load limit perfect information GM (1,1) and unequal-step GM (1,1). Following updating of model system information, development trend reflecting data system is newly added, which can help improve prediction precision of model. Average absolute relative error of predication value of coal gangue CFG single pile load limit obtained based on Usher model and measured value from static load test is 2.71%. According to prediction result of load limit of piles, Usher model is better than grey theory model and is of higher prediction precision.(5) Based on finite element analysis of coal gangue CFG model and common CFG model by using ANSYS software program, stress, strain and aberration nephogram is obtained. The two piles are compared and analyzed. It is found that following improvement of gangue replacing ratio, coal gangue CFG model load limit is decreasing and deformation and common CFG model piles are similar, which is in line with test result. |
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