On Overloading Design Method for the Slope of Deep Foundation Pit with Layered Soil Braced by Soil Nail

2013 ◽  
Vol 438-439 ◽  
pp. 724-727
Author(s):  
Li Hua Li
Keyword(s):  
Design Method ◽  
Limit Equilibrium ◽  
Work Rate ◽  
Layered Soil ◽  
Plastic Limit ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Soil Nail ◽  
Limit Equilibrium Theory

Based on plastic limit equilibrium theory of soil, the suitable values of energy safety factor are discussed here from energy work rate, the new design method for vertical slope of deep foundation pit with layered soil braced by soil nail with even overloading on slope top is proposed and engineering example is given out.

scholarly journals Analysis of Seepage Characteristics of a Foundation Pit with Horizontal Waterproof Curtain in Highly Permeable Strata

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1303
Author(s):  
Chenghua Shi ◽  
Xiaohe Sun ◽  
Shengli Liu ◽  
Chengyong Cao ◽  
Linghui Liu ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Theoretical Calculation ◽  
Calculation Method ◽  
Design Method ◽  
Water Pressure ◽  
Water Inflow ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Seepage Characteristics

At present, jet-grouted horizontal waterproof curtain reinforcement has become an essential method for deep foundation pit groundwater control. However, there is still a lack of an effective theoretical calculation method for horizontal waterproof curtain reinforcement, and there is little research on the seepage laws of foundation pits under different horizontal waterproof curtain conditions. Based on Darcy’s seepage theory, theoretical analysis models of deep foundation pit seepage were established considering the effect of a horizontal curtain in a highly permeable formation. Through the established models, the calculation method of the water inflow and the water pressure under the condition of a horizontal curtain was derived. Then through indoor tests, the reliability of the theoretical calculation method was verified. Furthermore, the established theoretical calculation method is used to analyze the influence of various factors on the water inflow and the water pressure, such as the ratio of hydraulic conductivity of the horizontal curtain to surrounding soil, thickness, and reinforcement position of the horizontal curtain. It is found that the hydraulic conductivity ratio has the most significant influence on the seepage characteristics of the foundation pit. Finally, the design method was applied to an example of the horizontal waterproof curtain of the foundation pit, which is located at Juyuanzhou Station in Fuzhou (China). The water inflow per unit area is 0.36 m3/d in the foundation pit, and this implies that the design method of the horizontal waterproof curtain applied for the excavation case is good and meets the requirements of design and safety.

Application of Prestressed Anchor Composite Soil Nail Wall in Deep Foundation Pit Engineering at Lanzhou Region

2014 ◽  
Vol 1030-1032 ◽  
pp. 714-718
Author(s):  
Hui Tao
Keyword(s):  
Soil Layer ◽  
Horizontal Displacement ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Soil Nails ◽  
Change Rate ◽  
Deep Foundation Pit ◽  
Soil Nail ◽  
Support Engineering ◽  
Prestressed Anchor

The paper introduces the application of prestressed anchors and soil nails support system in complex soil layer deep foundation pit engineering at Lanzhou region based on the deep foundation pit engineering in Gansu Provincial Hospital of TCM as the background and discusses its key technology. The effect shows that scheme of the design of foundation pit support engineering is reasonable and effective.The engineering meets requirements of design and environment.The monitoring results show that prestressed anchors can control the horizontal displacement and the change rate of slope′s vertical settlement effectively. The experience of engineering is significance for similar engineerings at Lanzhou region.

Filed Test Studies on Internal Force of Pile in Pile-Anchor Supporting System for Deep Foundation Pit

2011 ◽  
Vol 383-390 ◽  
pp. 7713-7717
Author(s):  
Chong Fu Wu ◽  
Chang Hong Li
Keyword(s):  
Limit Equilibrium ◽  
Internal Force ◽  
Pile Head ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Building Foundation ◽  
Zero Position ◽  
Prestressed Anchor ◽  
Variation Rule

Through the field test on the laboratory building foundation pit engineering of Northeastern University at Qinhuangdao, the distribution and variation rule of steel stress and pile moment is researched and analyzed in the process of the deep foundation pit excavation. The result shows that foundation pit excavation and applied prestressed anchor are the main factors of pile internal force change, furthermore, the latter is more effective than the former. Meanwhile, the influence of top beam to steel stress and moment of pile head can not be ignored especially. The zero position of steel stress and pile moment are basically same, which lies under foundation pit bottom. The use of limit equilibrium method more economical than elastic subgrade method in design over foundation pit bottom, however, which is opposite under it.

Slope Stability Analysis Based on Limit Equilibrium and Numerical Analysis

2012 ◽  
Vol 256-259 ◽  
pp. 198-202
Author(s):  
Kai Yu Jiang ◽  
Jing Cao ◽  
Yue Ma
Keyword(s):  
Numerical Analysis ◽  
Slope Stability ◽  
Difference Method ◽  
Limit Equilibrium ◽  
Natural State ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Calculation Results ◽  
Shear Strength Reduction

Based on the background of a foundation pit slope of the tertiary strong weathered basalt(TSWB), a quantitative analysis of the slope stability is proposed by combination of the limit equilibrium and the numerical analysis. The analysis also considers the effects of the natural state and soaking state Then, as an example, an ultra-deep foundation pit slope (UFPS) is analyzed under the background of TSWB. The Janbu method is used in the limit equilibrium because it can meet all the equilibrium conditions, including the force and moment equilibrium equation. The Lagrangian difference method which based on shear strength reduction is adopted in numerical analysis. Some meaningful conclusions can be obtained through comparing analysis the calculation results of Janbu method with finite difference method. These conclusions can be given a reference to similar projects.

scholarly journals Soil Pressure and Deformation Analysis of Small Size Deep Foundation Pit

2022 ◽  
Vol 2148 (1) ◽  
pp. 012061
Author(s):  
Zhao Long ◽  
Yilei Shi ◽  
Weili Li ◽  
Shuaihua Ye
Keyword(s):  
Finite Element ◽  
Limit Equilibrium ◽  
Side Wall ◽  
Soil Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Finite Element Software ◽  
Pressure Calculation ◽  
Space Effect

Abstract In this paper, the influence of space effect on soil pressure and deformation of deep foundation pit was considered, and the finite soil pressure calculation model was established. The soil pressure of deep foundation pit was calculated by assuming the slip surface and using the finite soil limit equilibrium theory. Then, PLAXIS 3D finite element software was used to establish finite element models of different plane sizes and depths. The distribution regulation of side wall soil pressure and deformation of deep foundation pit was calculated. Finally, the results of finite soil pressure calculation was compared with finite element method. The results shown that: The soil pressure of small deep foundation pit was affected by space effect, and the soil pressure and deformation decrease significantly along the foundation pit depth. Shear fracture Angle was related to the ratio of width to depth of foundation pit, and it was no longer a constant value of 45°+φ/2. Therefore, the spatial effect should be considered in the calculation of soil pressure of small deep foundation pit. The research results can provide some guidance for the design and calculation of similar small size deep foundation pit.

A Simplified Calculation Method for Spatial Effect in Large-Long-Deep Foundation Pit and its Analysis

2011 ◽  
Vol 243-249 ◽  
pp. 2762-2770 ◽  
Author(s):  
Ming Feng Lei ◽  
Li Min Peng ◽  
Cheng Hua Shi ◽  
Yun Liang Zhang ◽  
Wen Hua Li
Keyword(s):  
Numerical Simulation ◽  
Failure Modes ◽  
Limit Equilibrium ◽  
Equilibrium Analysis ◽  
Theoretical Research ◽  
Flow Rule ◽  
Spatial Effects ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit

According to the research status of construction spatial effects in large-long-deep foundation pit: mainly focus on numerical simulation, but theoretical research is not too many by now, a simplified method for calculating the construction spatial effects of large-long-deep foundation pit in cohesive soil was advanced. The soil layers around deep foundation pit were equal to cohesion-less isotropic soil mass by introducing the concept of equivalent internal friction angle. And then, by means of limit equilibrium analysis method combined with soil plasticity upper bound theory and associated flow rule, the spatial effects of two 3D failure modes: tension crack-shear and pure shear in deep foundation pit was studied concretely, and the corresponding formulas of spatial effects coefficient were put forward, also two examples were analyzed. The research results indicates that the method, which can complete by hand-calculation, avoids the defects of low efficiency, high cost and long period in numerical simulation, and the distribution characteristics and value size of spatial effects coefficient could be obtained directly from its calculation results, which can be used as guidance for the supporting structure, construction scheme design and the test points or sections choice in process of information monitoring.

Mechanical Analysis of Enclosure Pile under Different Constraints

2011 ◽  
Vol 90-93 ◽  
pp. 485-489
Author(s):  
Li Guo ◽  
Peng Li He ◽  
Guang Jun Zhang
Keyword(s):  
Mechanical Analysis ◽  
Subway Station ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Retaining Structure ◽  
Cantilever Structure ◽  
Reinforcement Measures

The enclosure pile is extensively used as retaining structure in the foundation pit excavation. And it is always combined with other reinforcement measures. So it is unreasonable to a certain degree that the enclosure pile is analyzed as cantilever structure. Taken the deep foundation pit of a subway station in Hefei for instance, the effect of other reinforcement measures on restrained conditions of enclosure piles in the paper was taken into account. And the behavior of enclosure pile under various restrained conditions was analyzed. Based on that, some helpful suggestions for practical retaining structure of foundation pit were put forward.

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