Investigation into performance of deep excavation in sand covered karst: A case report

Elbaz, Khalid; Shen, Shui‐Long; Tan, Yi; Cheng, Wen-Chieh

doi:10.1016/j.sandf.2018.03.012

Cited by 59 publications

(30 citation statements)

References 66 publications

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“…e shapes of the karst cave are complex in actual projects [21,22]. In the previous studies (simulations or tests) of karst cave, some researchers chose a rectangular cave [23,24], and some chose spherical cave for analysis [22]. Based on the previous studies, the rectangular cave is reasonable for the analysis of bearing capacity.…”

Section: Hypothesis and Simplification Of Calculation Modelmentioning

confidence: 99%

Influence of Karst Caves at Pile Side on the Bearing Capacity of Super-Long Pile Foundation

Wang

Ding

Zhang

2020

Mathematical Problems in Engineering

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The differences in development and situation of karst caves lead to two kinds of karst caves, and the karst cave may be on the pile side or at the pile bottom, which has a different influence on the bearing capacity of pile foundation. The paper presents a numerical analysis of the influence of karst caves at pile side on the bearing capacity of super-long pile foundation in karst areas. According to the size of pile foundation of a real bridge project, this paper modelized karst caves and investigated the karst cave from the effect of length, height, and thickness of roof on horizontal and vertical bearing capacity of pile foundation. The main conclusions can be drawn as: when the horizontal displacement at the top of pile foundation is greater than 0.05 m, the horizontal load is correlated positively with the length of karst cave; when the vertical displacement is greater than 0.07 m, the vertical load is correlated negatively with the thickness of the roof of karst cave. However, the height of karst cave has little effect on the bearing capacity; also the existence of karst cave has little influence on the dynamic response of pile foundation. The results of this study can be important with reference to the design and construction of pile foundations in karst areas.

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Section: Hypothesis and Simplification Of Calculation Modelmentioning

confidence: 99%

Influence of Karst Caves at Pile Side on the Bearing Capacity of Super-Long Pile Foundation

Wang

Ding

Zhang

2020

Mathematical Problems in Engineering

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“…The variation range of void ratio was between 0.7 and 0.85, and the optimum cohesion value was 40 kPa. More information about the tunnel section and the geological conditions can be found in Elbaz et al [49,50].…”

Section: Project Detailsmentioning

confidence: 99%

Optimization of EPB Shield Performance with Adaptive Neuro-Fuzzy Inference System and Genetic Algorithm

et al. 2019

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The prediction of earth pressure balance (EPB) shield performance is an essential part of project scheduling and cost estimation of tunneling projects. This paper establishes an efficient multi-objective optimization model to predict the shield performance during the tunneling process. This model integrates the adaptive neuro-fuzzy inference system (ANFIS) with the genetic algorithm (GA). The hybrid model uses shield operational parameters as inputs and computes the advance rate as output. GA enhances the accuracy of ANFIS for runtime parameters tuning by multi-objective fitness function. Prior to modeling, datasets were established, and critical operating parameters were identified through principal component analysis. Then, the tunneling case for Guangzhou metro line number 9 was adopted to verify the applicability of the proposed model. Results were then compared with those of the ANFIS model. The comparison showed that the multi-objective ANFIS-GA model is more successful than the ANFIS model in predicting the advance rate with a high accuracy, which can be used to guide the tunnel performance in the field.

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“…With the development of urban infrastructure, a growing number of deep excavation projects have appeared in China [1][2][3][4][5]. In many cases, deep excavation constructions are inevitably built below the water table in urban environments, especially in the coastal regions of China.…”

Section: Introductionmentioning

confidence: 99%

Novel Excavation and Construction Method for a Deep Shaft Excavation in Ultrathick Aquifers

Cao

Shi

Liu

et al. 2019

Advances in Civil Engineering

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Dewatering using the dewatering systems composed of diaphragm walls and pumping wells is commonly adopted for deep excavations that are undertaken in deep aquifers. However, dewatering can sometimes induce environmental problems, especially when diaphragm walls cannot effectively cut off the aquifers. This paper mainly presents an innovative excavation technique combining dewatering excavation and underwater excavation without drainage, which is employed for a deep shaft excavation in ultrathick aquifers (up to 60–70 m thick aquifer) in Fuzhou, China. The shaft excavation with the depth of 41.6 m below the ground surface (BGS) is divided into two major phases, that is, (1) the first part of the excavation (the depth of 23.6 m BGS) is conducted by the way of conventional dewatering and braced excavation (Phase I) and (2) the second excavation with the depth of 23.6 m to 41.6 m BGS is carried out by the novel underwater excavation without drainage technique (Phase II). Field monitoring results show that the ratios of maximum ground surface settlement δvm to the excavation depth He in this case ranged from 0.03% to 0.1%. Most of the ratios of maximum lateral wall deflection δhm to excavation depth He are less than 0.1%. All these results are lesser than that predicted by empirical methods, which also confirmed the applicability of this innovative excavation. Thus, this innovative solution can be applicable to other deep excavations that are undertaken in ultrathick aquifers, especially for the excavation of coarse sediments with high permeability.

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Investigation into performance of deep excavation in sand covered karst: A case report

Cited by 59 publications

References 66 publications

Influence of Karst Caves at Pile Side on the Bearing Capacity of Super-Long Pile Foundation

Influence of Karst Caves at Pile Side on the Bearing Capacity of Super-Long Pile Foundation

Optimization of EPB Shield Performance with Adaptive Neuro-Fuzzy Inference System and Genetic Algorithm

Novel Excavation and Construction Method for a Deep Shaft Excavation in Ultrathick Aquifers

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