Experimental Study on the Evolution Mechanism of Landslide with Retaining Wall Locked Segment

The failure of locked segment-type slopes is often affected by rainfall, earthquake, and other external loads. Rainfall scours the slope and weakens the mechanical properties of rock-soil mass. At the same time, rainfall infiltrates into cracks of slope rock mass. Under the action of in situ stress, hydraulic fracturing leads to the development and expansion of rock cracks, which increases the risk of slope instability. Under seismic force, the slope will be subjected to large horizontal inertial force, resulting in slope instability. In this paper, a self-developed loading device was used to simulate the external loads such as rainfall and earthquake, and the model tests are carried out to study the evolution mechanism of landslide with retaining wall locked segment. Three-dimensional laser scanner, microearth pressure sensors, and high-definition camera are applied for the high-precision monitoring of slope shape, deformation, and stress. Test results show that the retaining wall locked segment has an important control effect on landslide stability. The characteristics of deformation evolution and stress response of landslide with retaining wall locked segment are analyzed and studied by changing the slope shape, earth pressure, and the displacement cloud map. The evolutionary process of landslide with retaining wall locked segment is summarized. Experimental results reveal that as the landslide with retaining wall locked segment is at failure, the upper part of the landslide thrusts and slides and the retaining wall produces a locking effect; the middle part extrudes and uplifts, which is accompanied with shallow sliding; and compression-shear fracture of the locked segment leads to the landslide failure.

Deformation Behavior and Damage-Induced Permeability Evolution of Sandy Mudstone Under Triaxial Stress

The permeability and mechanical behavior in sandy mudstone are crucial to the hazard prevention and safety mining. In this study, to investigate the evolution and characteristic of permeability and mechanical properties of mudstone during the in-site loading process, triaxial compression-seepage experiments were performed. The increase of permeability and decrease of mechanical strength gradually evaluated to the decrease of permeability and increase of mechanical strength subjected to the increase of confining stress from 5 to 15 MPa, which corresponds to the transformation from brittleness to ductility of mudstone, and the transformation threshold of 10 MPa confining stress was determined. The shear fractures across the sample at brittle regime, while shear fracture does not cross the sample or even be not generated at semibrittle and ductile state. The dynamic decrease, slight decrease, and residual response were determined in axial strain, and the divided zone increases with the increase of confining stress. The relatively higher permeability corresponds to the higher pore pressure as the increase of confining stress. The volumetric strain increases as the increase of confining stress, compared to that decrease correspond to the increase of the pore pressure, and the higher volumetric strain and the lower permeability. In addition, an improved permeability model was developed to describe the loading-based permeability behavior considering the Klinkenberg effect.

Simulation of tectonic stress field and prediction of fracture distribution in shale reservoir

In this paper, a finite element-based fracture prediction method for shale reservoirs was proposed using geostress field simulations, uniaxial and triaxial compression deformation tests, and acoustic emission geostress tests. Given the characteristics of tensile and shear fractures mainly developed in organic-rich shales, Griffith and Coulomb – Mohr criteria were used to calculate shale reservoirs' tensile and shear fracture rates. Furthermore, the total fracture rate of shale reservoirs was calculated based on the ratio of tension and shear fractures to the total number of fractures. This method has been effectively applied in predicting fracture distribution in the Lower Silurian Longmaxi Formation shale reservoir in southeastern Chongqing, China. This method provides a new way for shale gas sweet spot optimization. The simulation results have a significant reference value for the design of shale gas horizontal wells and fracturing reconstruction programs.

Robust Heterojunctions of Metallic Alloy and Carbon Fiber-Reinforced Composite Induced by Laser Processing

The development of heterojunctions with a strong bonding interface between metals and non-metals has attracted much attention owing to their great potential for use in lightweight structures. Laser joining technology, which emerged as a fast and reliable method, has proven its feasibility and unique advantages in joining metal to polymer matrix composites. Herein, an optimized laser joining configuration has been employed to realize high-quality joining of titanium alloy and carbon fiber-reinforced composite. Cross-sectional microstructures of laser-produced joints reveal that micro-bubbles near the interface have been effectively suppressed and eliminated due to the continual clamping pressure applied to the joined area during the joining process. Tensile tests suggest that the joint strength increases with structure density on a titanium alloy surface, and the greatest fracture strength of joints reaches more than 60 MPa even after experiencing a high–low temperature alternating aging test. For higher structure density (>95%), the joints fail by the fracture of parent plastics near the joined area due to the tensile-loading-induced peel stress at the edges of the overlap region. Otherwise, the joints fail by interfacial shear fracture with breakage when the structure density is lower than 91.5%. The obtained high-performance heterojunctions show great potential in the aerospace and automotive fields.

The Establishment of Ore-Controlling Fracture System of Baoginshan Gold Mine Based on Fracture-Tectonic Analysis

The Baoginshan quartz vein type gold mine in the Baimashan-Longshan-Ziyunshan gold belt is the object of study, and the nature of the fracture structure and its ore-controlling effect are studied through surface and pit investigation, and the nature of the ore-controlling structure system and combination pattern of the Baoginshan gold mine is established. The F7 and F9 fractures in the near-east-west (EW) direction are the main fractures, which tend to the north and control the spreading of the ore zone; the northwest (NW) direction secondary tension fracture, with a dominant yield of 221°∠63°, is a T-type fracture in the Riedel shear mode and is the ore-holding structure of the vein-like ore body; the northeast-east (NEE) direction secondary shear fracture, with a dominant yield of 343°∠53°, is a P-type fracture and the combination of the two controls the specific positioning of the ore body. The characteristics and nature of the fracture structures in the whole ore zone, as well as their combination patterns, indicate that the overall ore-controlling fracture system of Baoginshan is a right-going tensional shear fracture zone composed of NW-oriented (T-type) and NEE-oriented (P-type) secondary fractures with F7 and F9 fractures as boundary fractures. The directions of the principal stresses are σ1≈158°∠40°, σ2≈288°∠38°, and σ3≈42°∠28°, respectively. In the next step of the prospecting process, based on increasing the spacing of prospecting pits (to 40m), in-pit drilling is deployed in the upper and lower discs of the NEE secondary fracture along with the tendency and strike for literacy, which can significantly improve the efficiency and effectiveness of prospecting and greatly reduce the cost of prospecting.

Efficacy of antiglide plate in vertical shear fractures of medial malleolus due to supination adduction injury around ankle: a prospective clinical study

Background: Ankle fractures represent 10% of all fractures with an incidence of around 137/100000 population per year, making these the second most common lower limb fractures after hip fractures. Increasing age, obesity and alcohol abuse are the major causal factors for the fractures around the ankle joint. These are typically low energy injuries with the majority occurring due to simple falls or sport. The aim was to open reduction and internal fixation of these with an antiglide plate.Methods: The present prospective study was carried out at government medical college Amritsar, Punjab in 25 patients of same demographic profile, March 2018 to December 2020 after having the clearance of ethical committee. All the patients after careful assessment of the injury both clinically (pain, swelling, deformity, any blisters) and radiologically (type of fracture, that is, vertical shear fracture of medial malleolus) were internally fixed under spinal anesthesia, with an antiglide plate after reduction of the fracture fragments.Results: The results were assessed accordance with Olerud-Molander ankle score (OMAS). We achieved excellent to good results with an average OMAS score of 80/100 in the present study.Conclusions: The open reduction and internal fixation of vertical shear fractures of medial malleolus with an antiglide plate is an effective way of management of these fractures. It ensures maximum stability and more so safeguards against loss of reduction or the implant failure under axial loading and at the same time ensures the timely union of such fractures without any significant complications.