Advanced Materials Research Vol. 831

Abstract: In humid region, the natural vegetation coverage has not restored well on the side-slope of the newly-regulated rivers before the first rainy season comes. The plants which are planted on the side-slope have also not grown enough roots to stabilize the side-slope. As a result, on the sandy side-slopes serious erosion and collapse often occurs. Thus, in order to safely ride out the first rainy season after regulation, this paper presents some ecological slope-protection measures to utilize annual ryegrass and willow branches. The experiments show that planting annual ryegrass on the sandy side-slope can effectively prevent the side-slope from eroding and safely ride out the first rainy season after regulation. Meanwhile, the restoration of native vegetation wont be hindered. If the sandy side-slope is steeper, i.e., its stability is poorer, besides planting annual ryegrass, planting willow branches-root hedges in the side-slope is also necessary. Planting willow branch-root hedges can improve the survival rate of willows and the closure of plant hedges, and thus significantly enhance the stability of sandy side-slope.

Abstract: This paper offers a Government-Enterprise-Public cooperation mode of emission trading in the Tai Lake Basin based on the governing theory of the common pool resources. Then, the motivation and restriction mechanisms have been designed, that is, a water environmental regulation contract with the effect of incentive and constraint penalty is signed between the water environmental management institute and the enterprises. Further, a principal-agent model is developed, by which a set of results of the water environment regulation optimal contract is obtained. The effects of public participation and local government protection probability on the contract are analyzed. The results show that the increase of public participation could decrease the optimal fine amount, which will weaken the contradictions between the local government and the enterprises, and the decrease of the local government protection probability would reduce the regulatory frequency, correspondingly the supervision cost will be low.

Abstract: An extensive finite element analysis was performed to study the settlement behavior of vertically loaded piles entirely embedded in non-homogeneous rock. To avoid utilizing interrelated parameters, pile-rock relative stiffness was expressed as a function of the elastic modulus of rock mass near the pile head that does not depend on pile length. Cases of pile-rock stiffness ratios that are typical for reinforced concrete piles bored in sedimentary rocks were investigated. Charts were developed to predict the elastic settlement of vertically loaded piles in non-homogeneous media. An equation was also introduced to incorporate the effect of rock non-homogeneity in estimating the depth at which settlement becomes insensitive to the increase of pile length.

Abstract: The behavior of reinforced and unreinforced embankment on soft and stiff grounds has been investigated using the centrifuge tests and verified using numerical simulations. Four different cases have been investigated in this study based on various types of foundation materials and reinforcement condition. Two-dimensional (2D) and three-dimensional (3D) finite element programs, Plaxis 2D and Plaxis 3D Foundation respectively used to simulate and analyze the prototypes behavior provided by centrifuge tests. Deformation behavior, settlements and effect of reinforcement have been studied in this study. Comparison of the results of the numerical analysis with the measurements obtained from the centrifuge tests shows good agreement in terms of settlement and the reduction of settlement due to geosynthetics reinforcement.

Abstract: This paper presents the results of centrifuge tests performed to investigate the behavior of geotextile-reinforced soil walls beyond stress conditions. The models were built using nonwoven fabrics as reinforcement layers and dry sand as backfill. Digital image analysis techniques were used to determine the displacement of sand markers placed along the reinforcements. The models were loaded until failure by increasing centrifugal acceleration, and the movements of the sand markers were used to determine the strain distributions along the reinforcement layers. The results revealed that stresses redistribute among reinforcement layers as models approach failure. Current design methods for GRS walls were found to be conservative when applied to predict the behavior of the reduced-scale models.

Abstract: It rains more concentrated in the summer with high temperature and strong evaporation in Gansu province, wetting-drying cycles usually occur in the embankment. Different collapse and uneven settlement appeared on the embankment in loess areas. Based on those engineering disease, through wetting-drying cycles tests of compacted loess, results show that void ratio increased, dry density decreased and cohesion significantly reduced with violent wetting-drying cycles. This illustrates that wetting-drying cycle has a significant impact on compacted loess and makes well-compacted loess with collapsibility again, it is the important reason of uneven settlement of embankment in northwest loess areas.

Abstract: A model waste mixing with kaolin, sand, and peat was developed. The physical properties of the waste were compared with the real municipal solid waste (MSW). The influence of unit weight on compression factor, shear strength, and saturated hydraulic conductivity was acquired. In addition, the homogeneous of the soil model was detected using the IWHR 450g-ton centrifuge and the newly developed centrifuge-robot.

Abstract: Density is one of the most important soil parameters. However, it is difficult to measure the density of soil model during centrifuge in flight. The cone penetration test (CPT) with robot provides a useful tool to determine the soil density of different models, as the cone resistance is closely related to soil density. This paper presents the correlation between cone resistance and relative density of sand, by doing centrifuge tests with robot CPT. Based on the test results, a formula that describes the correlation between cone resistance and sand relative density of Fujian standard sand is proposed for IWHR CPT attached to centrifuge robot.

Abstract: A large railway bridge is using (46.4 + 64 + 46.4) m double-line prestressed concrete continuous girder. In the construction process, bottom slab concrete in the mid span appears serious bursting crack phenomenon. Through the whole bridge stress analysis and closure segments locally fine finite element stress analysis, it appears tensile stress and large compressive stress in operational stage. Finally the bottom slab reinforcing schemes are proposed. It makes the following conclusions by analysis: (1) through the overall and local analysis stresses meeting the design requirements after reinforcement; (2) according to the domestic and foreign research experience, bursting crack reason of bottom slab is that prestressed pipes deviation from the design positions and anti-collapse steel bars are not set in place.

Abstract: With the development of railway transportation, the traffic load increased continuously and it had the adverse effect on the system of pier-foundation. The quantitative analysis of the load supplied on the top pier is necessary for analyzing the dynamic response of pier-foundation system. Based on the theory of vibration inverse analysis and finite element method, the paper identified the dynamical load supplied on the top pier in vertical and the transverse direction. Combined with the vibration and acceleration history measured by the field test in Xiaolinhe Bridge, the vertical and transverse direction vibration-load history curves were calculated when the train speeds were 153 km/h and 206 km/h respectively. The results indicated that the amplitude of dynamic load increased with the higher speed of train.