European Journal of Computational Mechanics

Research on The Interaction Mechanism and Stability Analysis of Unsaturated Soil Slope and Support Structure

Song YuPin — 2024-08-12

Unsaturated soil, as a widely existing soil in nature, has significant differences in mechanical properties compared to saturated soil. Especially when considering water migration and changes, its stability issues become more complex. Therefore, in-depth research on the interaction mechanism and stability of unsaturated soil slopes and support structures is significant. This study first analyzes the mechanical properties of unsaturated soil and the influence of water migration on soil strength based on the principles of unsaturated soil mechanics. It establishes a mechanical model for unsaturated soil slopes. Subsequently, the pseudo-dynamic method was used to simulate the response of slopes under dynamic loads such as earthquakes and rainfall, and the deformation and failure modes of unsaturated soil slopes were explored. Regarding support structures, this article studies the interaction mechanism between retaining walls, anchor rods, and unsaturated soil slopes. A mechanical model of the interaction between the support structure and unsaturated soil slopes was established by analyzing the influence of the support structure on the distribution of soil pressure on the slope, as well as the stability and bearing capacity of the support structure itself. In terms of stability analysis, this article uses numerical analysis methods such as the limit equilibrium and finite element methods to evaluate the overall stability of unsaturated soil slopes and support structures. Suggestions for optimizing the design of support structures were proposed by comparing the stability performance of slopes under different support schemes. The experiment shows that increasing soil cohesion by 1kPa per unit area can increase the stability coefficient by about 5%. The interface friction angle between the fill and the wall back increases by 1 degree, resulting in an increase of approximately 7% in the overturning stability coefficient.

Study on The Influence of Freezing and Thawing Cycle and Dry and Wet Alternation on Mechanical Properties and Engineering Application of Loess Slope

Ruheiyan Muhemaier — 2024-08-12

This article selects typical high-slope loess along the Baolan high-speed railway as the research object. Firstly, laboratory testing methods are used to conduct direct shear and consolidation tests on loess under freeze-thaw cycles, dry-wet alternation, and their combined effects to study the changes in its mechanical properties. The experiment found that rainfall infiltration is different due to different slopes. The negative pore water pressure at the top of the slope rapidly increased from −176.52 kPa to −139.094 kPa, and the volumetric water content also rapidly increased from 14.11% to 16.63%. The negative pore water pressure at the foot of the slope increased to −76.33 kPa, and the volumetric water content was 22.11%. At a given dry density, as the moisture content increases, regardless of the type of specimen, its cohesion, internal friction angle, and compression modulus gradually decrease while the porosity increment and compression coefficient increase. At a given moisture content, as dry density increases, regardless of the type of specimen, its cohesion, internal friction angle, and compression modulus gradually increase while the increment of porosity and compression coefficient gradually decrease. However, the internal friction angle, porosity increment, and compression modulus response to freeze-thaw action are closely related to initial dry density. At a given dry density and moisture content, as the number of cycles increases, the cohesion and compression modulus of the sample gradually decrease while the increment of porosity and compression coefficient increase.

Study on the Mechanical Properties and Bearing Capacity of Ultra-High Performance Concrete Members

Jing Diao — 2024-08-12

It is used as pier column members in viaducts, urban overpasses and industrial and civil building structures. In practical engineering, short columns or ultra-short columns with relatively small shear span may be formed, and shear failure may become the control condition for components and even structural damage. Under the action of large concentrated load or strong earthquake, the key parts of the high-rise structure and beam bridge system are obviously shear, leading to the serious brittleness and poor ductility of the components, which leads to serious structural continuity collapse, and then brings the loss of life and property. Therefore, it is important to study the shear properties of corrugated concrete members and to study the mechanical properties of components under complex load coupling. TRC comparison, 10 mm incision 100 mm from both ends. The specimen is equipped with 8 HRB400 longitudinal bars of 12 mm diameter along the length direction, the center of the longitudinal bars is 105 mm from the center of the specimen, and the steel content is 1.84%; the longitudinal bars with HPB300 stirrup of 100 along the axial direction, and the steel content of the stirrups is 0.68%. The results show that because the corrugated steel pipe can provide sufficient constraint for the internal core concrete and steel, the corrugated CFCT members have better ductility than the constrained concrete members under the small shear span ratio, which can effectively delay the occurrence of brittle shear failure. The curved shear test study of 12 corrugated concrete filled steel tube specimens was carried out, and the test phenomenon and failure mode of the components under different shear span ratio conditions were compared and analyzed. The study shows that when the shear span ratio is not greater than 0.2, the specimen shear error is obvious, mainly shear failure; when the shear span ratio is between 0.2 and 2.0, the specimen bending shear failure. With the increase of the shear span ratio, the specimen failure form is closer to the bending failure.

Development of an Equation-Free Surrogate Model using Deep Learning Algorithm for Heat Transfer Simulation

Somayeh Afzali — 2024-08-12

The significant computational costs and time associated with accurate simulation of physical phenomena make the simulation of nonlinear systems based on differential equations impractical for real-time prediction. Deep learning with its high potential in understanding nonlinear and unknown phenomena can be a suitable alternative to equation-based modeling. However, the success of deep learning highly relies on the availability of large-scale labeled data. To solve this problem, weakly supervised learning helps us. This algorithm can train models using only a limited amount of labeled data. In this work, a new definition of the loss function was presented, which can greatly reduce our need to prepare labels for network training through weak supervision. We used this approach for 2D heat transfer modeling. The present work consists of two steps: (1) Extracting the equilibrium temperature pattern directly from only 400 thermal data and encoding it in a convolutional kernel that forms the loss function; and (2) unsupervised training of the model using this loss function instead of the labels without observing any thermal data. The effectiveness of the proposed model in terms of accuracy, the number of labeled data used, and the time required for training the network was evaluated and compared with three supervised models trained on large data sets. Despite using less data, our model achieved higher accuracy compared to a supervised model trained from direct observation of 5000 labeled thermal data (0.68% vs. 1.5% error), which has a longer training time than our model (20 vs. 12 hours); and the cGAN-based model despite using more than 10 times more labeled thermal data (0.68% vs. 1% error).