Abstract:In order to analyze the factors affecting the bearing performance of recycled concrete-filled steel tubular short columns, three square hollow sandwich recycled concrete-filled steel tubular short columns with different eccentricities were designed for monotonic loading to verify the applicability of the established finite element model; Using the verified finite element model, seven specimens of recycled concrete-filled steel tubular short columns with three section types (square sleeve, square hollow section, square sleeve circular hollow section and square solid section) are designed.Taking eccentricity and outer steel tube wall thickness as variable parameters, the finite element analysis model was established by using ABAQUS finite element software for static loading analysis. The load axial displacement curves of recycled concrete filled steel tubular columns with different eccentricities and external steel tube wall thickness were obtained, and the influence of eccentricities and external steel tube wall thickness on the bearing capacity of recycled concrete filled steel tubular short columns was analyzed. The results show that the bearing capacity of three types of recycled concrete short columns with hollow intercalation of square steel tube increases with the decrease of eccentricity or the increase of wall thickness of outer steel tube; Among the three cross-section types, the square hollow sandwich specimen has the highest initial stiffness and ultimate bearing capacity.

Abstract:In order to enhance the seismic resistance of double steel plate concrete, I-type steel was introduced to effectively inhibit the end flexion of the component. With the cross-section form of steel pipe, I-shaped steel size and shear span ratio as the main parameters, the finite element model of 18 double steel sheet concrete combined shear wall was designed using ABAQUS finite element software to compare the seismic resistance of hysteresis performance, carrying capacity, energy consumption capacity, deformation and ductility and stiffness degradation. The research results show that the carrying capacity, ductility, stiffness degradation and energy consumption capacity of the terminal reinforced steel pipe-double steel plate concrete combined shear wall are greatly improved compared with the ordinary steel pipe-double steel plate concrete combined shear wall components. With the increase of shear span ratio, the peak load of end reinforcement component, yield load, ductility, initial stiffness and the peak of equivalent viscosity coefficient are greatly improved. The cross section form of steel pipe and dark column and type steel size have no significant impact on the seismic performance of components. Component AZ22-2.0 seismic resistance performance is superior.

Abstract:Considering the problem that channel steel insertion is easy to cause bending instability, a structural measure of setting batten along the channel steel is proposed. Based on the spatial coordination method, a theory of the stiffening effect of the batten was proposed, and the overall stability calculation method of channel steel axial compression member with batten was deduced. It provides a theoretical basis for local reinforcement optimization design of open channel steel in engineering. Numerical examples show that this method can effectively quantify the position effect and size effect of the plate. The regularity of stable critical load of the number and width of the plate, arrangement mode and length of the member is analyzed. The calculated results are basically reasonable and verify the application effect of practical engineering.

Abstract:At a large number of disaster sites, it has been found that even if the ground inclination is extremely flat (1°~5°), the ground surface may undergo long-distance lateral deformation due to earthquake loads. In order to understand the deformation characteristics of this kind of sand, the research used the concept of water inflow in an improved hollow cylindrical torsion shear tester. Subsequently, a constant shear stress static liquefaction test was used to determine the possibility of sample flow under drainage conditions and small initial static shear conditions.In order to highlight the comparison, the same sample was used for the undrained cyclic loading test to observe its behavior characteristics. The research found that:(1) The continuous flow characteristics of Toyoura sand can be observed under small initial static shear stress; (2) The continuous flow characteristics of sand are determined by the initial density, which also affects the volume expansion characteristics of sand; (3) The static liquefaction test shows that the flowing sand sample can flow under the water gushing mechanism, and even if the sample is liquefied, it shows non-flowing characteristics in a typical undrained test. This study enriches the related research on the fine sand area, and can provide a certain reference for sand liquefaction analysis.

Abstract:In order to study the influence of CaCl₂ solution injection in different grouting sequence on the electrochemical reinforcement effect during anode and intermediate holes grouting, three groups of experiments were carried out, which were injected at the same time(S1), injected at an interval of 5 h(S2) and injected at an interval of 12.5 h(S3).By monitoring the drainage, current, soil settlement and penetration resistance of treated soil, the three groups of experiments were compared and analyzed. The results show that the combination of anode and intermediate holes grouting can promote the uniformity of treatment effect in the upper and lower half of the area, delaying the grouting time of the intermediate hole is beneficial to increase the total drainage. Grouting in the intermediate hole at different times promotes the consolidation settlement in the lower half of the area. In the three groups of tests, the final settlement at each point of S2 test is more uniform than that of S1 and S3 tests. After the experiment, the distribution range of penetration resistance in the upper and lower halves of the S2 and S3 groups is significantly larger than that of the S1 group, grouting in the intermediate hole earlier is not conducive to the reinforcement of the upper and lower half areas.

Abstract:The stability evaluation of rock slopes in earthquake-prone areas is of great significance. Based on the pseudo-dynamic method, the calculation formulas of the stability safety factor of the rock slopes along river under different conditions was derived. Through parameter analysis, the impact of the seismic resistance of rock slopes such as horizontal and vertical seismic force, depth of cracking and fissure water, slope overload, anchoring effect, and flowing water erosion on the stability of rock slopes against overturning under different rock mass magnification factors was studied. Studies have shown that under different working conditions, the crack water accumulation, the horizontal seismic force, and the erosion of flowing water are not conducive to the stability of the rock slope against earthquake overturning, but the vertical seismic force, anchorage force, anchorage height, slope top overload, etc. are conducive to the seismic stability of rock slopes against overturning; with the increase of the rock mass amplification factor, the influence of horizontal and vertical seismic forces on the stability of rock slopes against overturning increases, slope crest overload, water depth of tension cracks, anchoring stress, anchoring height, and river water level have less influence on the anti-overturning stability of rock slopes, while the anchoring inclination angle and the height of scouring at the foot of the slope have less influence on the anti-overturning stability of the slope.

Abstract:The soil-rock interface is a common binary geological structure in the remediation of rock slopes. Based on the fiber reinforcement technology, this paper studies the coupling stability between the fiber composite clay substrate and the bottom. Through the sliding friction test, the influence of moisture content, sisal fiber content and other variables on the sliding process of the soil at the contact interface is studied. Combined with the micro analysis, the improvement mechanism of sisal fiber on clay is explored. The main research results are as follows:(1) With the increase of moisture content, the average value of dynamic friction coefficient of the sample increases first and then decreases. The critical friction angle α increases to the maximum value first and then decreases with the increase of moisture content. When the moisture content of the sample is between the plastic limit and the liquid limit, there is an optimal moisture content value to maximize the dynamic friction coefficient and the critical friction angle, and the adhesion effect of the clay sample is the best. (2) With the increase of fiber content from 0% to 1.2%, the average dynamic friction coefficient and the critical friction angle of the sample increase first and then decrease. The addition of sisal fiber can effectively improve the sliding failure resistance of the sample, but the reinforcement effect will be weakened with the increase of fiber content. The coupling effect of fiber composite clay and acrylic plate contact interface is the best when the content of sisal fiber is 0.8%.

Abstract:The deformation monitoring of underground structures is no longer sufficient to prevent disasters. Therefore, the prediction of underground structure deformation is necessary. In the study, two dynamic prediction models of GM(2,1) and LSTM are combined to predict the tunnel settlement under artificial mountain, which used the NSGA-Ⅱ algorithm considering two evaluation indicators to achieve better prediction results, based on the long-term monitoring data of a tunnel project. The results show that LSTM can ensure higher prediction accuracy and can better simulate the development trend of settlement, meanwhile the gray model is difficult to simulate more local settlement changes. The combined models can quickly obtain the optimal weighting scheme under multiple evaluation indexes with the NSGA-Ⅱ algorithm. It can combine the advantages of each model, and get a more accurate prediction effect.

Abstract:This paper established analytical model of pipe-soil system under freezing-thawing, conducted thermo-mechanical coupling analysis of the system under fault movement, and investigated the strain developing law. Different soil stiffness at different temperatures, leads to different pipe-soil interaction and different strain development laws of the pipe under fault movement. By comparing the numerical results of the force field under the real temperature field and the simplified temperature field, it is found that the strain law corresponding to the two temperature fields is quite different, and the local buckling of the pipeline is obviously earlier than the tensile failure. It is recommended that for the buried pipeline across the frozen soil fault, it is necessary to obtain the true pipe-soil temperature field by finite element simulation considering the temperature of the soil ground and pipe fluid, and then adopt the strain under fault movement for the seismic design or checking computation.

Abstract:In order to study the seismic response of suspended pipelines under earthquake, a simple test device for suspended pipelines was designed and manufactured. Pseudo dynamic tests of nine pipelines under two acceleration conditions were carried out to study the influence of suspended length, buried depth and pipe diameter on the seismic response of suspended pipelines. The consequences indicate that:Under the seismic load, the strain of the pipe is approximately anti-symmetrically distributed on both sides of the pipe with the center of the overhanging section as the symmetry axis, and the peak strain of the pipe appears near the junction of the overhanging section of the pipe and the soil body; under the large displacement condition, the peak strain of the pipe increases with the increase of the overhanging length, decreases with the increase of pipe diameter, and decreases with the increase of burial depth.

Abstract:Aiming at solving the problem of road and bridge damage and frequent accidents caused by vehicle overload, which always lead to serious loss of people's life and property, the concept of road and bridge "fuse" was proposed in order to maintain the safety and normal service of roads and bridges, the road and bridge anti-overload facility for combined friction was developed. It can realize the functions of automatic identification and restriction of vehicles exceeding the allowable traffic load of roads and bridges. The facility is composed of platform, slider group, limit reset device and alarm device. Automatic identification of overloaded vehicles is realized through the balance force system formed by the vehicle and the facility; when the overload vehicle passes through, the slider group produces linkage slip, and the right slider lifts, so as to restrict the overload vehicle's passage; the limit reset device controls the sliding speed of the slider group and restores the original position of the slider group to ensure vehicle safety and facility operation. The stress state diagrams of the sliding blocks were provided respectively under whole vehicle overload ultimate equilibrium condition, overload slip equilibrium condition and jack jacking reset condition, and the balance equations of the slider group were established. The design method and case of the facility based on the load limit of roads and bridges were given, and the weight measurement accuracy control measures of the facility were put forward.

Abstract:In order to explore the deep denitrification efficiency of sulfur autotrophic denitrifying filter for reclaimed water from municipal sewage treatment plant, this study takes Handan East Sewage Treatment Plant as the research object adopting a pilot experiment to simulate the actual production situation, meanwhile under the experiment to analyze the pilot operation problems and calculate the operating cost. The result shows:the treatment scale of test system is 200 m³/d; the direct operating cost is 0.13 yuan/m³; the nitrate nitrogen removal effect is significant as the removal rate is above 98%; This pilot-scale experiment can effectively reduce the total nitrogen in the effluent, without affecting other effluent indicators.

Abstract:In order to establish the shallow groundwater level control index system in Guangping County, firstly the characteristics of the shallow groundwater level change in Guangping County were analyzed, and then the multiple regression analysis method was used to determine that the main influencing factor of the shallow groundwater level is the extraction volume, followed by Precipitation. Well irrigation return replenishment and canal irrigation field infiltration replenishment have no significant impact on shallow groundwater level, and control the rate of shallow groundwater drop and shallow groundwater extraction. Through the multiple linear regression analysis method and the inverse distance weighting method (IDW) in ArcGIS software, the control indicators for the lower limit of the groundwater level of each representative monitoring well, each township in different hydrological years in 2030 were obtained, thereby establishing a shallow layer Groundwater level control index system. The results show that by 2030, all townships in Guangping County will become areas where groundwater level is basically stable or water level rises. In 2030, the shallow groundwater level of Guangping County will be buried in different hydrological years. The lower limit control index is 31.69-34.66 m.

Abstract:Aiming at the pressure pulsation of water pump turbines, computational fluid dynamics (CFD) was used to carry out the numerical analysis of the whole flow channel. 61 monitoring points were set up along the circumferential direction in the bladeless area between the movable guide vanes and the runners, and the pressure fluctuations in different working conditions of the hydraulic turbine working conditions and the water pump working conditions was analyzed. The relationship between the flow field and pressure pulsation under different working conditions was analyzed. The results show that the pressure in the bladeless zone of the hydraulic turbine working condition and the pump working condition presents a periodic distribution on the time and space scale. The pressure distribution of the hydraulic turbine working condition is mainly determined by the runner blades, and the pressure pulsation of the pump working condition is mainly determined by the movable guide vanes.The pressure pulsation of the pump working condition is stronger than that of the hydraulic turbine working condition.

Abstract:In order to improve the recognition rate of handwritten numbers, we have improved AlexNet network model in this paper. Conv3 and Conv4 were introduced to replace the model for Inception-resnet module, which improves the feature extraction capability of the model. The Batch Normalization (BN) method was used to accelerate network convergence and prevent overfitting,reducing the number of convolutional kernels and improving the training speed of the network. In this paper, training and testing are carried out on MNIST data sets. Experimental results show that the improved network model has a better detection accuracy of 0.9966, which proves the effectiveness of the algorithm.

Abstract:The benefit distribution mechanism of Water Saving Management Contract (WSMC) is imperfect, which affects its development process. Taking users and Water Service Companies (WSMC) as participants, this paper studies the benefit distribution of benefit guaranteed WSMC by using the hierarchical sharing model for the first time. Firstly, the degree of WSCO effort and knowledge input coefficient were selected as the influencing factors to establish the income model of both sides. Secondly, according to the change of influencing factors, it analyzed the enthusiasm of WSCO's efforts in the two cases of WSCO only obtaining management expenses and WSCO participating in excess profit distribution, and determined the profit proportion of both sides when making excess profits. Finally, an example was given to verify the effectiveness of the model. The results show that:(1) When WSCO participates in excess profit distribution, the degree of effort is higher and the total profit of the project is higher. (2) WSCO's work effort is positively correlated with the efficiency coefficient of knowledge input and the proportion of excess profit distribution. This paper provides a reference for the benefit distribution of WSMC under the benefit guarantee mode.