Landslides are a typical geological hazard that can cause large numbers of casualties and huge economic losses, and the overflow of a weir from a blocked river landslide can have even more disastrous consequences. Of the different types of landslides, about 33% of landslides happen in anti-dip slopes. This paper reports a massive ancient anti-dip river-damming landslide on the Jinsha River: the Zongrongcun landslide. Field investigation and theoretical analysis were used to reveal the potential mechanism of this ancient landslide, and the block discrete element software 3DEC was used to replicate its landslide process. The findings from the present study are as follows: (1) blocks in this landslide were classified into significant slide, significant toppling, and significant slide categories based on Df. (2) The whole landslide was divided into significant sliding and toppling zones by Df = 0.5. (3) The results show that the river-damming landslide was likely to be triggered by river erosion, heavy rainfall, gravity. Under strong valley trenching, the rocks on the slope fractured under gravity and tectonic stress. These factors caused rock blocks tensile fracture failure. Then a penetrating sliding surface formed on the slope, which subsequently caused this river-damming landslide.
The hollow structure of large-diameter ring piles (LDRPs) reduces the amount of concrete used, is economically efficient, and reduces the weight of the pile. However, its bearing characteristics and safety performance are still not fully known. In this study, to determine the properties of the LDRP structure, a combination of the indoor scale model test and numerical simulations was used, and a new parameter, K, which is the thickness-to-diameter ratio, was introduced. A comparative study of LDRPs with different hollow ranges was conducted. The results show that for a value of K in the range of 0.2–1, the ultimate bearing capacity of LDRPs is not significantly different from that of large-diameter solid piles (LDSPs), and they can ensure sufficient safety reserves. Under ultimate bearing capacity, the strain on an LDRP is large, but it does not exceed its own material strength, and the strain variation law is similar to that of a solid pile. LDRPs show the characteristics of end-bearing piles, and concrete savings can reach up to 50% for K in the range of 0.2–1.
In recent years, there has been a rise in the construction of expansive underground structures and shield tunnels with exceptionally large diameters. These projects introduce unique challenges regarding their impact on the surrounding soil and structures, which differ from those typically encountered in conventional shield tunnels. However, the existing body of research in this specific domain remains insufficient. When such tunnels intersect deep foundation pits supported by piled-raft foundations, the discrepancies in soil deformation can become even more pronounced. At present, there is a dearth of research on the underlying principles governing these differences, and theoretical investigations have not kept pace with practical engineering applications. Consequently, the existing settlement prediction methods employed for diverse projects need to be reevaluated and adjusted to accommodate the distinctive characteristics of each individual project. Regarding the engineering focus of this paper, it is crucial to recognize that soil subsidence in the pit bottom has a significant influence on the mechanical response of the piles. Consequently, the implementation of targeted correction measures remains consistently important. Based on this concept, this paper focuses on a super-large diameter shield tunnel project that under-crossed a deep foundation pit with a piled-raft foundation. The influence of different construction methods on the settlement law of the soil at the bottom of the deep foundation pit is discussed after verification of the accuracy of the model through numerical simulation and field monitoring data. Additionally, two correction coefficients that consider the project’s load characteristics are proposed in this research. These coefficients were used to correct the surface settlement curve. The corrected soil settlement curve at the pit’s bottom can successfully reflect the numerical simulation results, which in turn can reflect the mechanical response of the pile under the influence of tunnel excavation.
A remote real-time monitoring system was developed for the remote real-time monitoring of mine slope deformation and internal forces. The system is based on cloud-computing technology and a 5S multimedia streaming monitoring data transmission system. It has now been applied to an open-pit iron mine in Nanfen to monitor the horizontal displacement of potential sliding surfaces. Compared with geometric monitoring methods in traditional geodetic surveying, the results show that this monitoring system has higher accuracy (0.01 mm) and the ability to monitor in real time for 24 h. These features can realize early warnings of mine slopes from multiple dimensions, and provide a guarantee for safe, continuous and the efficient production of mines. In addition, it can provide a certain reference for the prevention and control of mine slope disasters, and is beneficial to the application of information-based early warning technology.
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