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Zhu Y.,Hubei Engineering University | Yu H.,Hubei Engineering University | Yang Y.,Northwest Research Institute of Engineering Investigation and Design | Jia Z.,Hubei Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

The purplish-red mudstone of the Badong group appears in large numbers in the highway from Yichang to Badong. When the weathering mudstone was used as the fillings of highway embankment, lots of engineering problems appeared, such as road bulges, shoulder of road gushing, the uneven settlement and the lower bearing capacity. In order to eliminate the undesirable properties of embankment soil, a modified experiment was conducted with lime, cement, fly ash. The compaction test, California bearing ratio (CBR) test, unconfined compression test, disintegration test by using self-made disintegration instrument and soil-water test were conducted to study the characteristics of improved soil. The microstructure of improved soil was scanned by environmental electron microscope. When the improvement effect was evaluated; the basic indices such as bearing ratio, unconfined compressive strength, expansion index were not only considered but the index of soil-water characteristics and resistance of disintegration were also tried to be analyzed. The results show that the expansion characteristics of purplish-red mudstone is eliminated by modified materials. The bearing capacity of the subgrade soil and unconfined compression strength are vastly improved. The characteristics of water stability and resistance of disintegration are also improved. The improvement effect of the improved soil mixed with cement is the best, the best cement proportioning is 5%. The improvement effect of improved soil mixed with lime is the better and the best mixing ratio of lime is 7%. The improvement effect of fly ash soil is the worst and the best mixing ratio of fly ash content is 11%. To increase the fly ash content may make the improved effect to be better. Source

You Z.,Hubei Engineering University | Wang L.,Hubei Engineering University | Yang Y.,Northwest Research Institute of Engineering Investigation and Design
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

Joint roughness coefficient(JRC) is one of the key factors affecting the discontinuity shear strength. The research on the discontinuity roughness and shear strength anisotropy is of great significance to engineering rock mass deformation and stability analysis. Currently, there are few papers reported on the discontinuity fractal dimension and its shear strength anisotropic analysis based on three-dimensional(3D) laser scanning technology. Taking a dam site in Guizhou Province for example, discontinuity surface morphology data obtained through 3D laser scanning are used to establish a digital elevation model to evaluate shear strength anisotropic of dolomite joint. On the basis of the variation function method, the anisotropy of discontinuity fractal dimension is studied and corresponding functional relationship between JRC and fractal dimension(D) is established. According to Barton standard contour curve and the actual stress state of dolomite, anisotropies of shear strength parameters based on the Barton equation are examined. The results show that cohesion and fiction angle change within the range of 0.20 to 0.75 MPa and 9.09° to 36.87°, respectively. The anisotropies of cohesion and friction angle are obvious, and the cohesion increases as the friction angle decreases in the same shear direction. Source

Wang L.,Xian University of Technology | Nie M.-Q.,Xian University of Technology | Su J.-M.,Northwest Research Institute of Engineering Investigation and Design | Wang Z.-Y.,Xian University of Technology | And 2 more authors.
Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology

The effects of metabolites of anthracene or phenanthrene on the biodegradation of anthracene or phenanthrene have been studied. The results showed that the natural state of metabolic mixtures of anthracene or phenanthrene exhibited promoting effects on biodegradation of anthracene or phenanthrene, the removing rates of anthracene were increased by 3.07%~6.10% within 156 h, and those of phenanthrene were 13.14%~30.35% within 60 h. The biodegradation processes of anthracene or phenanthrene by Bacillus sp. CN2 could be described as first-order kinetics, and the only difference was that the values of k (the rate constant in the kinetic equation) for control groups were less than that of the degradation systems with addition of metabolic mixtures. The results also indicated that adding metabolic mixtures could enhance the biodegradation rate of anthracene and phenanthrene more obvious during earlier degradation stages than later stages, and for anthracene, the degradation rate increased by 0.281~1.20 mg/L·h within 2 h, and for phenanthrene, it was 0.570~1.13 mg/L·h. The metabolic mixtures could function as pH value buffer actions for the degradation fluids, so the pH values decreased slower than control groups. Source

Wang X.-G.,Northwest Research Institute of Engineering Investigation and Design | Wang X.-G.,Wuhan University | Hu B.,Wuhan University | Lian B.-Q.,Northwest Research Institute of Engineering Investigation and Design | And 3 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

Two kinds of dry and saturated shear rheological tests are carried out on the granite in Bangpu mining area of Tibet. According to the test results, the shear rheological properties of granite are analyzed. Based on the mechamical state characteristics of granite at accelerative shear rheological stage, an improved nonlinear viscoelasto-plastic rheological model is proposed. The core of this model mainly consists of Kelvin of τs (conditions for judging shear stresses) and modified nonlinear Newton components of εa (conditions for judging strain value). This model is able to reflect the rock rheological law under shear stress loads with different levels. By using the proposed model, the nonlinear characteristics of rocks at accelerative rheological stage can be well and resonably demonstrated. Parameter identification is carried out for the shear rheological text results of the granite in Bangpu mining area of Tibet. The obtained theoretical curves of modified nonlinear viscoelastic-plastic rheological model agree with the test data. The proposed model is validated to be correct and reasonable. Source

Wang X.,Northwest Research Institute of Engineering Investigation and Design | Wang X.,Wuhan University | Hu B.,Wuhan University | Zhao Z.,Northwest Research Institute of Engineering Investigation and Design | Lian B.,Northwest Research Institute of Engineering Investigation and Design
Journal of Natural Disasters

Loess joint commonly develops in loess area. From field geological investigation, it can be found that excavated loess slopes have many vertical joints in the survey area, and under the action of rainfall in the crack sliding surface, collapse sliding failures often occur due to the instability of the loess slope body combined with the vertical joints and lower flat dip loess joints. Thus a generalized three - dimensional numerical analysis model of loess excavation slope in open coal mine of the survey area was established to analyze pore water pressure, displacement, plastic zone area under three rainfall conditions (20 mm/day,40 mm/day, 100 mm/day) after two day rainfall. The conclusion is that, for loess slope excavation, attention should be paid to the combined sliding surface crack formed from loess vertical joints and slow angle loess joints. Thus, this is a feasible analysis method as to the loess slope collapse sliding deformation failure analysis and control for projects with similiar engineering geological conditions. Source

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