Case Study of a Failed Slope of a Port in Southern China

2013 ◽  
Vol 353-356 ◽  
pp. 3-6
Author(s):  
Yong Hua Cao ◽  
Chuan Zhi Huang
Keyword(s):  
Southern China ◽  
Soft Soil ◽  
Soil Layer ◽  
Soil Mass ◽  
Safety Factors ◽  
Soil Layers ◽  
Surface Method ◽  
Calculation Results ◽  
Hard Soil

Uniform safety factors are normally assumed in slope stability analysis and this assumption can influence the rationality of the analysis. New analysis methods were obtained based on Fellenius, Bishop and multi sliding surface method to study a failed slope of a port in southern China. The calculation results show that the safety factors of soft soil layers will be overestimated and the safety factors of hard soil layers will be underestimated if soil mass of slope vary widely in the strength. For the failed slope in this paper, the factors obtained with normal methods will be overestimated because of the hard soil layer of this slope.

scholarly journals Pre- and Postcollapse Ground Deformation Revealed by SAR Interferometry: A Case Study of Foshan (China) Ground Collapse

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Wu Zhu ◽  
Yan Zhang ◽  
Zhanke Liu ◽  
Qian Zhu
Keyword(s):  
Ground Deformation ◽  
Southern China ◽  
Soft Soil ◽  
Soil Layer ◽  
Sar Interferometry ◽  
Ground Subsidence ◽  
Soil Consolidation ◽  
Tunnel Excavation ◽  
Ground Collapse ◽  
Before And After

On the evening of 7 February 2018, a deadly collapse of a metro tunnel under construction in the Southern China city of Foshan caused 11 deaths, 8 injuries, and 1 missing person. For disaster prevention and mitigation, the spatiotemporal ground deformations before and after the collapse event were derived from 55 Sentinel-1A synthetic aperture radar (SAR) images spanning from March 2017 to January 2019. The results showed that prominent ground subsidence in the shape of a funnel with a maximum rate of 42 mm/year was observed in the vicinity of the collapse area before the accident. After the accident, the area and magnitude of subsidence decreased compared with precollapse subsidence. This decrease is related to the progress of tunnel excavation and groundwater changes. In the temporal domain, continuous subsidence was observed over a year before and after the accident, and accelerated subsidence appeared one month before the collapse accident. Soft soil consolidation and tunnel-induced soil losses were the main reasons for the subsidence over the study area. The leakage of groundwater accounted for the collapse event. The leaked groundwater eroded the soil, resulting in the formation of an arched hole. The connection between the arched hole and the tunnel reduced the bearing capacity of the soil layer above the arched hole, triggering the collapse event. The findings provide scientific evidence for future collapse monitoring and early warning due to tunnel excavation.

scholarly journals Ultimate capacity of piles penetrating in weak soil layers

2018 ◽  
Vol 162 ◽  
pp. 01025
Author(s):  
Ahmed Al-Obaidi ◽  
Pinar Mahmood
Keyword(s):  
Soft Soil ◽  
Soil Layer ◽  
Vertical Direction ◽  
Deep Foundations ◽  
Elastic Model ◽  
Ultimate Capacity ◽  
Weak Soil ◽  
Soil Layers ◽  
Dense Sand ◽  
Pass Through

A pile foundation is one of the most popular forms of deep foundations. They are routinely employed to transfer axial structure loads through the soft soil to stronger bearing strata. Piles generally used to increase the load carrying capacity of the foundation and reduce the settlement of the foundation. On the other hand, many cases in practice where piles pass through different layers of soil that contain weak layers located at different depths and extension, also some time cavities with a different shape, size, and depth are found. In this study, a total of 96 cases is considered and simulated in PLAXIS 2D program aiming to understand the influence of weak soil on the ultimate pile capacity. The piles embedded in the dense sand with a layer of weak soil at different extension and location. The cross section of the geometry used in this study was designed as an axisymmetric model with the 15-node element; the boundary condition recommended at least 5D in the horizontal direction, and (L+5D) in the vertical direction where D and L are the diameter and length of pile, respectively. The soil is modeled as Mohr-Coulomb, with five input parameters and the behavior of pile material represented by the linear elastic model. The results of the above cases are compared with the results found in a pile embedded in dense soil without weak layers or cavities. The results indicated that the existence of weak soil layer within the surrounding soil around the pile decreases the ultimate capacity. Furthermore, it has been found that increase in the weak soil width (extension) leads to reduction in the ultimate capacity of the pile. This phenomenon is applicable to all depth of weak soil. The influence of weak layer extension on the ultimate capacity is less when it is presentin the upper soil layers.

scholarly journals Experimental and Numerical Investigations on Hydraulic Barrier Bottom Plug for Deep Excavations: A Case Study

2021 ◽  
Vol 10 (4) ◽  
pp. 57-61
Author(s):  
An Phung Vinh
Keyword(s):  
High Reliability ◽  
Soft Soil ◽  
Soil Layer ◽  
Clayey Sand ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Geological Conditions ◽  
Reasonable Proportion ◽  
Hydraulic Barriers

In Vietnam, the solution of designing and constructing deep foundation pits with the geology of sandy or clayey sand is very difficult, especially in case soil mix mud. In some deep foundation pits, the unreasonable treatment solution causes the bottom plug of the foundation pit to be pushed up to the foundation pit or not to pump a foundation pit dried. Solving those problems, this article introduces a particular case study, sealing the bottom of the foundation pit for no 14 of Yen Xa drainage works with the Jet grouted bottom plug hydraulic barriers. To treat the soft soil layer, mix organic without breaking the upper soil layers, this solution uses Jet-grouting technology with a mixture of materials including cement, fly ash, blast furnace slag, lime in a reasonable proportion to ensure waterproof and not uplift the massive bottom plug hydraulic barriers when excavating soil in the pit. Results of calculation and acceptance after the foundation pit is completed show that this is a good solution, high reliability and can be applied to seal the bottom of the foundation pit in similar geological conditions.

scholarly journals Analysis of settlement prediction due to preloading and vertical drain applications on runway construction

2020 ◽  
Vol 156 ◽  
pp. 02002
Author(s):  
Adriyati Meilani ◽  
Rifa’i Ahmad ◽  
Faris Fikri
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soil Layer ◽  
Soil Mass ◽  
Research Area ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Consolidation Settlement ◽  
Primary Consolidation

Consolidation settlement is a general geotechnical problem particularly found in the area where is composed of soft soil. It is caused by the discharge of pore water pressure induced by the increase of stress in the soil mass. Construction of runway above soft soil requires analysis for stability related to the reduction of consolidation settlement and the recovery. This study aims to analyze the settlement comprehensively using empirical methods of Prefabricated Vertical Drains (PVD) and preloading installation. Preloading is a technique by which consolidation of soil can be achieved to a substantial amount before the imposition of actual construction load. According to soil investigation, the characteristic of the soil layer is clay soil, which has the potential to consolidation settlement. The result of the settlement analysis of the taxiway in the research area is from 33 cm to 214 cm. It takes ten years for primary consolidation to reach a 90% degree of consolidation. However, in the Hansbo method of Prefabricated Vertical Drains (PVD) and preloading are applied, with triangular configurations in depth of 11 meters and duration for variation embankment spacing of 1 m is 79 days, 1.5 m is 202 days and 2 m is 390 days. The conclusion of efficient distance of PVD installation and preloading is spacing of 1 m with 79 days for primary consolidation.

scholarly journals Method of Calculating the Compensation for Rectifying the Horizontal Displacement of Existing Tunnels by Grouting

2020 ◽  
Vol 11 (1) ◽  
pp. 40
Author(s):  
Yongjie Qi ◽  
Gang Wei ◽  
Feifan Feng ◽  
Jiaxuan Zhu
Keyword(s):  
Volume Expansion ◽  
Soil Layer ◽  
Horizontal Displacement ◽  
Soil Mass ◽  
Calculation Model ◽  
Additional Stress ◽  
Corrective Effect ◽  
Engineering Data ◽  
Subway Tunnels ◽  
Good Agreement

Sleeve valve pipe grouting, an effective method for reinforcing soil layers, is often employed to correct the deformation of subway tunnels. In order to study the effect of grouting on rectifying the displacement of existing tunnels, this paper proposes a mechanical model of the volume expansion of sleeve valve pipe grouting taking into consideration the volume expansion of the grouted soil mass. A formula for the additional stress on the soil layer caused by grouting was derived based on the principle of the mirror method. In addition, a formula for the horizontal displacement of a tunnel caused by grouting was developed through a calculation model of shearing dislocation and rigid body rotation. The results of the calculation method proposed herein were in good agreement with actual engineering data. In summary, enlarging the grouting volume within a reasonable range can effectively enhance the grouting corrective effect. Further, with an increase in the grouting distance, the influence of grouting gradually lessens. At a constant grouting length, setting the bottom of the grouting section at the same depth as the lower end of the tunnel can maximize the grouting corrective effect.

Geotextile encased columns (GEC) used as pressure-relief system. Instrumented bridge abutment case study on soft soil

2017 ◽  
Vol 45 (3) ◽  
pp. 227-236 ◽  
Author(s):  
F. Schnaid ◽  
D. Winter ◽  
A.E.F. Silva ◽  
D. Alexiew ◽  
V. Küster
Keyword(s):  
Soft Soil ◽  
Pressure Relief ◽  
Bridge Abutment ◽  
Relief System

Assessment of site conditions for disposal of low- and intermediate-level radioactive wastes: A case study in southern China

2012 ◽  
Vol 414 ◽  
pp. 624-631 ◽  
Author(s):  
Shuping Yi ◽  
Haiyi Ma ◽  
Chunmiao Zheng ◽  
Xiaobin Zhu ◽  
Hua'an Wang ◽  
...  
Keyword(s):  
Southern China ◽  
Radioactive Wastes ◽  
Intermediate Level ◽  
Site Conditions
Sign in / Sign up

Export Citation Format

Share Document