Gongcheng Kexue Yu Jishu/Advanced Engineering Science

To study the seismic performance of corrugated steel plate concrete-composite shear wall with replaceable component of wall toe, two shear wall specimens were designed and fabricated. The influences of different arrangement forms of corrugated webs on seismic performance of shear wall specimens were analyzed by quasi-static tests and ABAQUS finite element software. The test result indicated that the wall toes of the specimen were destroyed before the main member, and the damage was mainly concentrated on the replaceable components before the ultimate drift ratio was reached. Compared with the horizontal corrugated steel plate concrete-composite shear wall, the lateral bearing capacity of the vertical corrugated steel plate concrete-composite shear wall had increased by 18.3%, the ductility coefficient increased by 28.69%, and the energy dissipation capacity increased by 3.3 times; The rate of bearing capacity degradation and stiffness degradation, the equivalent viscous damping coefficient and the stiffness degradation ratio were all lower, and the initial stiffness of the latter was slightly improved, which demonstrated that the vertical corrugated steel plate concrete-composite shear wall had better mechanical and seismic performance. By comparing the ABAQUS finite element model analyses with the test processes, the failure mode was basically consistent with the test phenomenon, which indicated that the finite element model established in this article had a certain reliability.

In order to solve the engineering application problems such as low cohesion and poor water stability of silt in the alluvial plain of the Yellow River, the sintering red mud and matrix asphalt were utilized as the main materials to prepare red mud-asphalt powder curing agent (RAC) for comprehensively stabilizing the silt. Setting the optimum dosage of cement as 5% and adding 0, 2%, 4%, 6%, 8% RAC to form stable silt specimens, the compressive strength and uniaxial compressive elastic modulus tests were conducted at 3 d, 7 d, 28 d ages after standard curing, immersion softening, cyclic heating, low-temperature freeze-thaw and high-temperature self-healing methods. The change rules of comprehensive road performance of stabilized silt with different dosage of RAC were compared and analyzed. The scanning electron microscope (SEM) was used to observe the microstructure and pore characteristics of silt, cement stabilized silt and RAC stabilized silt, and then the mechanism of solidification and stabilization was discussed. Combined with the practical application of entity engineering, the road performance of RAC stabilized silt was tested and verified. The results showed that RAC stabilized silt had good mechanical properties and water stability compared to cement alone, the strength of 2%, 4%, 6%, and 8% RAC stabilized silt increased by 110%, 146%, 156%, and 161%, respectively after standard curing of 3 d, and the loss rate of immersion strength at 28 d age is reduced from more than 50% to less than 20%. The strength of cement stabilized silt increased slightly after 5 cycles of heating, but the strength of RAC stabilized silt increases by more than 140% when the dosage was higher than 4%. After the low-temperature freeze-thaw tests, the cement stabilized silt specimen cracked and damaged, the RAC stabilized silt specimen was intact, and the loss rate of strength was less than 15%. The specimen was loaded to 90% ultimate load and heated for 5 times, the strength change rates of 2%, 4%, 6%, and 8% RAC stabilized silt were –8.3%, –2.3%, 8.0%, and 12.9%, respectively. The SEM images showed that RAC stabilized silt had dense cemented aggregates and non-connected microporous structure with uniformly distributed pore diameter less than 1 μm, which were beneficial to improve the water stability and frost resistance of stabilized silt. The asphalt components wet-bonded and wrapped with silt particles and hydration products under high temperature conditions, which accelerated the diffusion to fill the internal pores and micro cracks and realized damage repair and structural reinforcement of stabilized soil. In the entity project, the road base was filled with “4% RAC+5% cement” stabilized silt. After opening to traffic, the overall bearing capacity and service condition of the road were in good condition through field coring and FWD deflection tests. There were no cracks, pits, loose and other damages.

As an effective means for the exploitation of Hot Dry Rock (HDR) resources, the Enhanced Geothermal System (EGS) has broad development prospects and a great utilization value. Therefore, it is particularly important to predict its capacity and longevity. In order to realize the productivity and longevity prediction of the double-well EGS, the productivity and longevity prediction methods of the EGS system under different working conditions were analyzed through theoretical derivation and numerical simulation. Firstly, based on the Dupuit formula and the endothermic formula, the EGS productivity and longevity control equation was established to provide theoretical support for EGS longevity prediction. Then, according to the groundwater flow equation and the heat transfer equation, combined with the Newton’s cooling law, five factors affecting the four unknown parameters in the EGS productivity and longevity control equation were analyzed. The four unknown parameters were the reduction of thermal reserves, the amount of geothermal compensation, the average conversion temperature of production wells, and the shape coefficient of thermal reserves. The five factors obtained were the initial temperature of thermal storage, the injection temperature of thermal medium, the volume of thermal storage, the specific surface area of thermal storage, and the EGS running time. Under the condition of considering the geothermal compensation, the three parameters of EGS with double-well were used to analyze, correct and quantify the influence factors of each unknown parameter when the thermal storage breakthrough occurred, and then obtained the prediction formula of the four unknown parameters changing with the five factors. Based on the above results, a method for predicting the productivity and longevity of the double-well EGS was obtained: using the EGS productivity and life control equation, the prediction formula of four unknown parameters, and the thermal reserve permeability to predict the productivity and longevity of the double-well EGS. Finally, the prediction method of production capacity and longevity of the double-well EGS was used to predict the working conditions of the existing literature and compare them. The two results were in good agreement, which proved the applicability of the control equation and the prediction formula and the accuracy of the prediction method.

The water holding capacity of unsaturated soils is usually reflected by the changing laws of soil-water characteristic curves. The important influence of factors such as load and temperature on the soil-water characteristic curve has been gradually recognized, but studies on the combined effect of moisture-load-heat on the soil-water characteristic curve are rarely reported, and the analysis of its dominant influence factors is even rarer. In order to explore the water holding capacity of silty clay under the combined action of moisture-load-heat, this paper carried out dry-wet cycle experiments of silty clay under different vertical stress and temperature conditions, and analyzed the influence mechanism, characteristics and characteristics of each factor. Importance, and established a predictive model reflecting the interaction of multiple factors. The research results show that With the increase of the vertical stress, the air intake value of unsaturated soil increases, the dehumidification rate decreases, and the hysteresis effect of the dry-wet cycle process becomes stronger, and it shows the same characteristics at all temperatures. Comparing the experimental curves under the same vertical stress and different temperatures, it is found that the air intake value of the soil is relatively slightly lower when the temperature is higher. The vertical stress has the greatest influence on the water holding capacity of the soil, but it is mainly limited to the low suction stage the dry-wet cycle has the second effect, and it will rapidly decay as the number of cycles increases the temperature has a small influence and is When the suction value or density is high, it can be ignored. The improved L model based on the Logistic curve is more suitable for the soil-water characteristic curve fitting of Badong silty clay than the commonly used V-G model. The comprehensive research results show that the root cause of the change of the characteristic value caused by the vertical stress is the change of the internal pore structure, which leads to the difference in water holding performance; temperature mainly affects the water holding performance of the soil in a low-stress and low-suction state 3 types The degree of influence of occurrence conditions on water holding capacity of silty clay is vertical stress>dry-wet cycle>temperature distribution the improved L model can effectively reflect the evolution of water holding capacity of silty clay under the combined action of moisture-load-heat feature.

Landslides often occur in steep mountain areas during heavy rainstorms. Establishing landslide prediction models is one of the essential strategies for disaster prevention in mountain areas. The kinematic subsurface-flow approximation and the infinite-slope instability analysis were used to develop a rainfall-induced shallow landslide prediction model. Firstly, the runoff hydrograph and the temporal variation of soil water storage were obtained by calculating the runoff yield and concentration of slope according to the theory of the kinematic subsurface-flow approximation. Then the temporal variation characteristics of saturated water level was studied. Finally, based on the theory of the infinite-slope instability analysis, and the analyzed slope stability the temporal variation of factor of safety was calculated. The Namasia District in Kaohsiung of Taiwan was chosen as a studied area to test the applicability of the model. It was found that the predicted location of landslide occurrence during Typhoon Morakot is consistent with those obtained from satellite images, and the values of the calibrated model parameters are consistent with physical meanings, which shows that the physically based model has good reliability. Moreover, the variation of the slope factor of safety was analyzed by applying double-peak design hyetographs with different rainfall peaks. The result showed that when the rainfall increases, the subsurface flow, and the saturated water level raise quickly to result in the decreasing of factor of safety value. On the contrary, while the rainfall decreases, the rate of subsurface outflow is higher than rainfall intensity, the saturated water level would drop slowly. Hence, the slope factor of safety is increasing and gradually returns to its natural state. Moreover, the influence of soil thickness on slope stability was further studied during the rainstorms. The results showed that factor of safety is reduced as the increasing of the soil thickness. It also reveals that if a low-peak rainfall occurs and followed by a high-peak rainfall, it would result in a higher possibility of landslides. It was expected that this study can give a clear physical explanation for the landslide occurrence and provide a useful tool for landslide prediction.