Abstract:Based on the limit equilibrium method, the impact of the hollow rate of prefabricated modules into the connection stability analyses of geosynthetic reinforced soil (GRS) walls was involed. The calculation formula of the tensile force and the resistance of the connection to assess the connection stability of GRS walls with prefabricated modular panel were established. Parametric studies were conducted to investigate the influence of the hollow module panel filler, the internal friction angle of the reinforced fill, the module width and the reinforcement spacing on the connection stability. The obtained results demonstrate the connection stability decreases with the increase of the module hollow rate, especially for the lower part of the retaining wall, the module with lower hollow rate and the compacted filling soil should be used in the actual project; the connection stability also decreases with the decrease of the module width and the increase of the reinforcement spacing, and it becomes more pronounced as the wall height decreases. It is recommended that the module width should not be less than 0.2 m, and the reinforcement spacing should not be exceeded 0.3 m.

Abstract:In order to study the structural noise of simply supported box girder, a 32 m simply supported box girder was taken as the research object to carry out a vehicle-bridge coupling dynamic analysis to figure out the vertical wheel-rail force under the effect of track irregularity. In the sound field analysis model of the simply supported box girder with the vertical wheel-rail force as the excitation, frequency distribution characteristics and propagation laws of the sound pressure were analyzed by the method of combining boundary element and finite element with the dynamic response result of the simply supported box girder as the boundary condition.The influence of traveling speed and plate thickness on the structural noise of simply supported box girder was mainly studied. Studies show that the frequency band of bridge structure noise is mainly below 100 Hz, and the noise sound pressure level above the roof is the largest; structure noise has obvious attenuation characteristics during the propagation process, and the noise sound pressure level decreases with the increase of the propagation distance; the higher the vehicle operating speed is, the greater the structural noise sound pressure is; the greater the box girder stiffness and roof thickness are, the lower the noise sound pressure level is;under the same load, the structural noise sound pressure level radiated by the single-box double-chamber box girder is lower than that of the single-box single-chamber box girder.

Abstract:In order to study the seismic performance of recycled aggregate concrete-filled double steel plate composite shear walls, the finite element software ABAQUS was used for model verification and analysis on the basis of existing tests. The research contents include replacement rate of recycled coarse aggregate, distance -thickness ratio, axial compression ratio and connector form. The results show that: (1) With the increase of recycled coarse aggregate replacement rate, the flexural capacity, shear capacity and initial lateral stiffness of the specimens have different degrees of deterioration; (2) when the axial compression ratio is 0~0.5, the bearing capacity decreases and the initial stiffness increases with the increase of it; (3) for the recycled concrete shear wall specimens with shear span ratio of 1.5 (replacement ratio of recycled coarse aggregate is 100%), the shear bearing capacity decreases with the increase of distance -thickness ratio; (4) the forms of connectors have little effect on the early bearing capacity and stiffness, but have a great influence on the shear and bending bearing capacity of the later loading period.

Abstract:Based on an engineering section in Zhejiang, field tests on exceptional energy piles with semi-buried pipes were carried out. By monitoring the temperature of the pile and the soil around the pile, the thermodynamic characteristics of the energy pile under hydrothermal circulation were studied. It was found that the temperature rise along the pile increased first and then decreased under temperature load, which indicated that the heat transfer effect of pile was more obvious at the greater depth. Values of soil temperature at different positions from different pile depths to the pile center were simulated by Matlab, and in the vicinity of the pile side, the soil temperature rose significantly. Therefore, the influence of thermal temperature cycle on the physical parameters of soil, such as heat transfer characteristics and mechanical properties, should be considered in practical application. The results show that the soil temperature within 1 m (2.5D, D is the diameter of the energy pile) from the pile center is affected by hydrothermal circulation for 48 hours. When the simulation time is extended to one year, the influence range of soil temperature field can reach 2.8 m (7D).

Abstract:In order to study the laws of the change of soil mechanical properties with temperature, the soil collected in the frozen soil area of the Tibet Plateau was re-prepared and subjected to different temperatures (15 ℃, 5 ℃, -5 ℃, -15 ℃) for direct shear test through an improved large-scale temperature-controlled direct shear equipment-FAST-1 under the condition of accurately controlling temperature changes and applying a large normal pressure. The temperature, shear strength, dilatancy effect, cohesion and internal friction angle were tested in the process of shearing. The test results show that the mechanical properties of silty clay can be changed greatly with the change of temperature. The shear strength of silty clay increases with the decrease of temperature under negative temperature condition, while the shear strength of silty clay remains almost unchanged under positive temperature condition. The maximum cohesion of silty clay under negative temperature is 1.8 MPa at -15 ℃, which is about 900 times of that under positive temperature. The internal friction angle shows a tendency of large change at both ends temperature and small change in the middle temperature. Due to the influence of temperature on cohesion and internal friction angle, the dilatancy of soil under negative temperature is obviously larger than positive temperature, up to 2.5mm, which is about 5 times of that under positive temperature.

Abstract:The stress relaxation of rock is related to the long-term stability in all kinds of rock engineering, and the influence of water cannot be ignored. The tests of single-stage stress relaxation and cyclic stress relaxation for dry and saturated sandstone were conducted, and the differences of relaxation behavior between the two states of samples were analyzed contrastively. The generalized Maxwell relaxation constitutive model with four elements was adopted for the implementation of numerical verifications. The results show that: 1) The sandstone in both states represents the typical incomplete attenuation characteristic; 2) under the same strain ratio, the final stress relaxation degrees in saturation state are slightly higher. The difference is mainly reflected in the development of stress relaxation, which is deeply affected by the weakening of water; 3) in the peak stress cyclic relaxation tests, the ductility of saturated samples increase due to water weakening and internal energy dissipation. Although the stress relaxation degree of dry samples is higher than that of saturated samples, the results are opposite for the number of cycles and axial strain at final failure; 4) the constitutive model of four-element generalized Maxwell stress relaxation can completely describe the whole process and the trend of single-stage stress relaxation for sandstone with high accuracy.

Abstract:Reducing the subjectivity of geological strength index GSI value and improving the accuracy of rock mechanics parameter value are crucial for surrounding rock stability. The sensitivity ranking of rock mass geological characteristic parameter’s to GSI was obtained by orthogonal test, and four parameters that had great influence on GSI were selected. The interval range of GSI was generalized by introducing the interval number of rock mass structural grade SR and structural plane surface SCR. The rock integrity coefficient K_Vand wave velocity ratio K’_V were introduced to perform linear interpolation for GSI interval range, so as to obtain accurate GSI value. Taking Qingjiagou tunnel as an example, the rock mass mechanical parameters estimated by this method were within the Ⅲ₂standard for surrounding rock. FLAC^3D was used to establish the tunnel excavation model.The relative error between the calculated vertical settlement value and the actual monitoring value was 1.5%, which verifies the reliability of this method.

Abstract:In order to study the unsaturated infiltration characteristics of yellow cotton soil containing spherical microplastics with different content and different particle size under rainfall conditions, a set of model test equipment for soil column vertical infiltration under simulated rainfall conditions was developed. Seven sets of rainfall infiltration tests were carried out on the yellow cotton soil. The result shows: (1) When the rainfall intensity is 20 mm/h, the microplastic particle size is 5 μmand the microplastic content is 0.05 %, rainwater infiltration is promoted, and the content of other microplastics prevents rainwater infiltration, and as the content of microplastics increases, the water point and saturation point appear earlier. (2) When the rainfall intensity is 20 mm/h, the content of microplastics is 0.25 % and the particle size of the microplastics is 3 μm, the infiltration of rainwater will be significantly promoted, and no water will be generated during the whole test period. When the particle size of the microplastics is 5μm and 8μm, a lot of water will be generated, which will block the infiltration of rainwater. (3) The hydrophobic effect of microplastics significantly affects the process of rainwater infiltration, but its impact on the peak water content is relatively weak. However, its impact on the peak water content is relatively weak, the peak water content gradually decreases with the increase of the microplastic content, and gradually increases with the increase of the microplastic particle size.

Abstract:Based on the pull-out test of center bonded specimen between the HRB400E crescent steel bar (HRB400E-CSB) and recycled aggregate concrete (RAC), the effect of the replacement rate of recycled fine aggregate and the dimeter of the steel bar on the bond-slip performance between the HRB400E-CSB and RAC was studied under the condition that the replacement rate of recycled coarse aggregate was 100%. Results show that the ultimate bond stress and initial bond stiffness between HRB400E-CSB and RAC decrease with the increase of the replacement rate of recycled fine aggregate and the steel bar diameterand the calculation formular of the ultimate bond stress of HRB400E-CSB and RAC is given by the least square method.

Abstract:Focusing on the stability of the pile-slab structure, FLAC^3D simulation calculation software was used to study the seismic response of pile-slab wall in the deposit slope under different parameters by numerical analysis method, and the seismic effect of pile-slab structure was evaluated. The results show that the dynamic characteristics of the structure have a significant effect on the seismic effect, and the seismic wave near the natural frequency of the slope has a greater damage to the slope; in the seismic intensity areas of VⅡ and VⅢ, the sheet pile wall can effectively play an anti-seismic role, but in the seismic intensity area of IX, the displacement of the pile exceeds 10 % of the pile length, which cannot meet the needs of anti-sliding; the difference of pile spacing directly affects the distribution of soil pressure on pile and in a certain range, the soil pressure on pile back will decrease with the decrease of pile spacing; influence of parameters of sliding body on back earth pressure of anti-slide pile is less than pile displacement; various factors should be considered in the design of pile - slab structure to avoid waste of resources.

Abstract:Based on the three-dimensional finite element transient fluid structure coupling calculation of Yanshan Reservoir Dam, the rainfall infiltration process of dam slope under heavy rainfall was simulated. On the basis of rainfall infiltration simulation results, combined with the particle characteristics analysis of dam slope cushion material and field survey results, the rainfall erosion process of dam slope cushion material was studied. The results show that: rainfall infiltration is the main cause of the erosion of the cushion material of the downstream dam slope, and the area where the hydraulic gradient is greater than the minimum critical hydraulic gradient of the cushion material is the main area of erosion; in the process of rainfall infiltration, with the continuous loss of fine particles, the particle gradation of cushion materials tends to deteriorate, and the voids between precast blocks and cushion materials appear; in order to ensure the safety of downstream dam slope, it is suggested to adjust and design the particle gradation of cushion material, improve the critical hydraulic gradient value of cushion material, and enhance the drainage capacity of dam slope by adjusting precast block and setting drainage ditch.

Abstract:Based on the grey system theory, the prediction model of water consumption in colleges and universities was established with five main factors affecting water consumption including number of people using water, land area, greening rate, water supply efficiency of pipe network and penetration rate of water-saving appliances, the grey correlation coefficient and correlation degree of each factor were calculated, and then the water consumption prediction model was used and analyzed. The prediction results show that excluding the influencing factors of vacation, the relative error between the predicted water consumption and the measured water consumption in other quarters is less than 5 %, and the posterior error ratio of the model is 0.089. The prediction results are basically consistent with the actual situation, and the prediction accuracy of the model meets the engineering standard.

Abstract:Aiming at solving the problems of poor noise sensitivity and accuracy in the filtering process of mobile robot LiDAR point cloud data, a weighted Gaussian filtering method was proposed. In this method, Gaussian filter and angle cosine were used as the weighted value to filter the radar point cloud data, which reduced the fluctuation of object contour scanned by LiDAR. Finally, the method was applied to the actual robot chassis of robot operation system. The experimental results show that the method can better solve the problems in the process of LiDAR point cloud filtering compared with the traditional Gaussian filtering method, and the scanned object profile is more smooth, and has good stability and accuracy, which is beneficial to the effect of LiDAR mapping.

Abstract:Aiming at solving the problem of ignoring semantic information in LDA model feature extraction, a disease text clustering algorithm LG&K-Medoide based on LDA and GloVe model was proposed. First, LDA was used to model the disease text data, and the JS distance was used to calculate the text similarity; second, GloVe was used to model the disease text data to obtain the word vector, the weight of the word vector was labeled according to the contribution to part of speech from disease text, and the cosine distance was used to calculate weighted text similarity based on GloVe modeling; finally, the two similarities are combined to improve the distance formula to realize K-Medoide clustering. The experimental results show that the LG&K-Medoide algorithm has higher accuracy than the clustering algorithm based on LDA, LDA+TF-IDF and LDA+Word2Vec models.

Abstract:Combined with the actual situation of the production line of order-oriented enterprises, the important factor of order rejection cost due to customer priority was added to the traditional order acceptance model, and the new whale optimization algorithm (WOA) was used to solve the problem. WOA was proposed to solve real number domain problems and had the defect of easily falling into local optimum. To solve this problem, an improved whale optimization algorithm (IWOA) was proposed. The coding method based on ranking and deviation degree was used to solve the integer domain problem of the order acceptance model. Adding a dynamic learning strategy from historical individuals could avoid premature algorithms to a certain extent. In order to prevent whale individuals from deviating from the optimal direction in the process of random search and thus affecting the convergence speed, the cross-selection strategy of genetic algorithm was used to eliminate inferior individuals. The experiment compares IWOA with WOA and the improved gray wolf algorithm (HGWO), which proves the advantages of IWOA in solving the order acceptance model, the stability of result, the convergence speed of the algorithm itself and the quality of initial solution, etc.

Abstract:In order to study the influence of different recycling models on the closed-loop supply chain(CLSC) decision-making under free-rider behavior, aiming at the closed-loop supply chain system composed of manufacturers, retailers and consumers, based on Stackelberg game, the manufacturer recycling model and the retailer recycling model were constructed, and the influence of different recycling models on the closed-loop supply chain decision-making is discussed. The study finds that free-riding has a negative impact on retailers and a positive impact on manufacturers; the choice of recycling mode has no effect on product pricing and demand, but has effect on recycling price; the manufacturer’s profit under the manufacturer recycling model is not necessarily higher than that under the retailer recycling model, but the retailer’s profit under the retailer recycling model must be higher than that under the manufacturer recycling model.