Analysis of Failure Models and Deformation Evolution Process of Geological Hazards in Ganzhou City, China

In Ganzhou City, China, a complex bedrock lithology and structure, diverse topography, frequent engineering works, and abundant rainfall generate frequent, sudden, small-scale landslides that are difficult to prevent and control. This study integrates evidence data from a field investigation of landslides with geological-engineering analogues to document the distribution and development of these geohazards in Ganzhou City. Based on the distribution of landslides across different types of bedrock and soil, we identify five lithological groups prone to slope failure: granite, metamorphics (slate and phyllite), red sedimentary layers, clastic sedimentary rocks with weak interlayers, and loose Quaternary deposits. Granite and metamorphic bedrock are the two lithologies most prone to landslides. Our analysis of the genesis and mode of slope failure suggests that most landslides in Ganzhou City originated from four modes of slope failure: scouring erosion collapse, steep slope collapse, rock sliding along a rock stratum, and wedge-shaped block sliding and caving. An in-situ model test and numerical simulations were used to explore the evolution of slope deformation and failure on the most landslide-prone lithological groups, and the accumulation of debris post-failure. This work provides a reference for the assessment of the risk from, and the management of, landslide geohazards in Ganzhou City and geologically similar regions.

Identification of Landslide with Resistivity Method at Candi Industrial Area, Ngaliyan, Semarang

Landslides can be occurred in almost every natural slope or artificial slope slowly or suddenly with or without any prior signs. The main reason for slope collapse is the increase in shear stress in the landslide, the decrease in shear strength, or both. Landslide problems can result in loss of life and property, damage to the environment, infrastructure, public facilities, and disrupt livelihood generally. Landslides can be detected by exploration of the subsurface. The geoelectrical method is one of the geophysical methods to know the change of resistance of a type of rock layer below ground level. The research aims to interpret the lithology of the subsurface in the Candi Industrial Area, Ngaliyan, Semarang using Schlumberger configuration. The results of measurements are voltage and electric current to calculate the apparent resistivity value processed by IP2Win software to determine the lithology and the slip surface area. The results present that lithology in the research area consists of sand clay, clay, and sandstone. The results showed that the locations of landslide-prone areas lie at the contact between sand clay and clay with that area at a depth of between 19.95 – 31.62 m there is one difference in the resistivity value which can be assumed to be a slip surface.The result of the research can be used to make policy rules of landslide mitigation.

Slope Collapse Detection Based on Image Processing

In this paper, we study a task of slope collapse detection (SCD) for river embankment and formulate it as the tasks of motion detection and image recognition. Specifically, we introduce an SCD method based on motion detection and image recognition technologies to help inspector attendants detect the slope collapse. In this method, we use the foreground motion detection algorithm to identify the slope collapse of the scene of the river embankment. Since the moving targets in the foreground may not only be the slope collapse but also maybe some biology, we further use the image feature extraction and image recognition technology to recognize the foreground motion area, thus eliminating the influence of the biology on the detection results. Experimental results on the relevant scene data show that the proposed method can identify the slope collapse in real-time, and can effectively eliminate the motion interference of the biology, which has a high practical value.

Improved Vulnerability Assessment Table for Retaining Walls and Embankments from a Working-Level Perspective in Korea

Climate change can lead to unpredictable slope collapse, which causes human casualties. Therefore, Korea has devoted significant effort to the management of slope disasters. The Ministry of the Interior and Safety of Korea, which oversees the safety of the nation’s people, has allocated a four-year budget of $557 million to investigate, assess, and maintain steep slope sites. However, there have been fatalities caused by steep slope site evaluations based on inadequate knowledge and a single retaining walls and embankments (RW&E) assessment table. Therefore, the assessment table for RW&E-type steep slopes needs to be improved in terms of its accuracy, simplicity, and ease of use. In this study, domestic and global evaluation methods were reviewed, problems associated with the existing RW&E assessment table were identified, and a focus group interview was conducted. The RW&E assessment table was improved through an indicator feasibility survey and analytic hierarchy processing. The improved assessment table was categorized from one to four classifications to reduce the ambiguity of the evaluation: concrete, reinforced soil-retaining walls, stone embankments, and gabions. This study will provide the sustainability of slope safety and serve as a reference for classification and evaluation criteria across all national institutions that conduct RW&E evaluations.

Exogenous relief-forming processes and phenomena on the territory of the Chechen Republic

Landslide, also known as landslide, is a geological phenomenon that includes a wide range of ground movements such as rockfalls, deep slope collapse and shallow mudflows. Landslides can occur at sea, on the coast and on land. While gravity is the main driving force behind a landslide, there are other factors that affect the initial stability of the slope. Typically, preconditions create certain subsurface conditions that make the site / slope prone to collapse, while the actual landslide often requires a trigger before being triggered. Landslide studies help identify weak areas, classify hillsides into different categories, and minimize the impact of landslides.

WAVE GENERATION DUE TO DEBRIS FLOW INTO A SMALL AREA OF WATER

It is known that the tsunami is generated by the debris flow due to slope collapse into the sea. The huge waves may cause damage to coastal structures and residents. Because of heavy rain in northern parts of Kyushu Island, Japan, in July 2017, many reservoirs were damaged and were destroyed. It has been reported that the huge waves may have been caused by debris flow due to the heavy rain. Many laboratory experiments and numerical simulations of the landslide-generated tsunami into the sea have been carried out to clarify the process of wave generation. However, there are a few studies of wave generation by debris flow into a small area of water such as a reservoir. In this study, model experiments of debris flow were conducted in a two-dimensional flume and numerical models based on the depth-averaged shallow water equations have been per-formed in order to clarify the hydraulic characteristics of the waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/r6r72KtkvL4

Reinforcement Effect of Inclined Prestressed Concrete Pipe Piles on an Inclined Soft Foundation

The embankment slope is vulnerable to slip and collapse, when prestressed concrete pipe (PCP) piles are used to reinforce the inclined soft foundation to bear the load of the embankment. Accordingly, this study puts forward new programs for strengthening embankment foundation with inclined, rather than vertical, PCP piles. Based on an actual engineering accident with embankment slope collapse, this study establishes a finite element model, accompanied by analysis of engineering characteristics and reinforcement effects of the foundation. The main conclusions are drawn as follows: (1) when a pile-supported foundation is used to strengthen the inclined soft foundation, PCP piles in the lower part of the embankment are subjected to bending moments, with their maximum value appearing in the upper part of the PCP pile at the embankment slope foot. During the embankment filling, the maximum pile bending moment may reach the ultimate bending load, resulting in bending failure accompanied with large lateral displacement and even slope collapse. The maximum horizontal displacement of the foundation is located at the foot of the embankment slope. (2) Reinforcement using inclined PCP piles contributes to smaller maximum pile body bending moments than that using vertical PCP piles and loading berms, and such contribution is enhanced when the inclination angle of PCP piles in the lower part of the slope gets larger. Therefore, inclined PCP piles with high angles are optimum in improving the overall stability of the foundation. (3) Compared with vertical PCP piles, inclined PCP piles contribute to smaller horizontal displacement and vertical settlement in foundation reinforcement, which means better reinforcement effects. Moreover, as the inclination angle of PCP piles increases, the maximum displacement decreases rapidly, associated with greatly enhanced lateral stability.

Physical Modeling Test on Deformation and Failure of Rock Slope with New Support System

In order to explore the monitoring and control method of rock slope, indoor physical model testing of collapse control and monitoring were carried out with the example of a rock slope collapse area project in Jietai Temple in Beijing, China, as the prototype. Based on the similarity theory, in this study, a new structural support with Negative Poisson’s Ratio bolt and flexible anchored net was utilized to reinforce the rock slope. Following a graded loading sequence, the collapse failure characteristics and the overall control effect of energy absorption reinforcement measures were explored. The experimental results demonstrated that the entire process of slope collapse presented four distinct stages of failure: fracture generation, fracture propagation, partial collapse, and overall collapse. The full-field displacement nephogram and the displacement monitoring point of the collapse area indicated that the large deformation and failure of the collapsed surrounding rock were effectively controlled, while the Negative Poisson’s Ratio bolt and the flexible anchored net had good reinforcement effects. The experimental stress record presented that the change of pressure curve was an apparent regularity in the entire process of slope collapse, which reflects the change state of internal force of surrounding rock; it includes the function of monitoring of slope collapse. It was indicated that the Negative Poisson’s Ratio bolt along with the large-deformation flexible anchored net had good reinforcement monitoring effect on the rock slope collapse disaster.