scholarly journals Study on Deformation and Stability of Rock-Like Materials Retaining Structure during Collaborative Construction of Super-Adjacent Underground Project

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Hongfu Qu ◽  
Lihua Wang ◽  
Chunlei Feng ◽  
Hualao Wang ◽  
Xuan Zhang
Keyword(s):  
Limit Equilibrium ◽  
Adjacent Area ◽  
Underground Engineering ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Retaining Structures ◽  
Retaining Structure ◽  
Collaborative Construction ◽  
Measured Deformation ◽  
The Difference

The collaborative construction of undercrossing tunneling of Gongchang Road and the adjacent Metro Line 6 extension station section in Shenzhen is difficult and of high risk. In view of these characteristics, this paper studied the deformation and stability of rock-like material retaining structures in the process of underground engineering collaboration by combining the measured deformation data and the circular slide theory based on the limit equilibrium method. The results show that due to the difference between the supporting systems of rock-like materials on both sides and other reasons, the upper part of the retaining structure and the limited soil in the adjacent area tilt greatly to one side at the same time, and the surface settlement in the limited soil area also increases with the increase of the excavation depth of the foundation pit. On the basis of measured deformation data analysis, the mechanical model for calculating the stability concerning the relationship between the adjacent distance L of the deep foundation pit and the vertical distance D ′ between the lowest support of the foundation pit and the bottom of retaining structures was established. Then, the calculation formula for the against basal heave stability covering different adjacent degrees was established. Besides, the applicability of the calculation method was verified by combining it with the actual engineering and related prediction theories, which further proves that the research results have certain theoretical value and engineering significance, and can provide a reference for the rock-like material retaining structures design and stability analysis of similar projects.

scholarly journals Transverse Force Analysis of Adjacent Shield Tunnel Caused by Foundation Pit Excavation Considering Deformation of Retaining Structures

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1478
Author(s):  
Xinhai Zhang ◽  
Gang Wei ◽  
Xinbei Lin ◽  
Chang Xia ◽  
Xinjiang Wei
Keyword(s):  
Bending Moment ◽  
Confining Pressure ◽  
Shield Tunnel ◽  
Additional Stress ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Retaining Structures ◽  
Absolute Value ◽  
Retaining Structure ◽  
The Absolute

In order to research the theory for the variety of transverse forces of the adjacent shield tunnels caused by foundation pits excavation, the effect mechanism of foundation pit excavation on the adjacent shield tunnel was analyzed. The sidewall unloading model of the foundation pit, considering the deformation of the retaining structures, was introduced to calculate the additional stress of soil caused by foundation pit excavation. On this basis, the additional confining pressure variation model of the adjacent shield tunnel was established, considering the influence of the longitudinal deformation. Take the deep foundation pit project by the side of the shield tunnel of Hangzhou Metro Line 2 as a case study, the variation in confining pressure distribution of the adjacent shield tunnel caused by foundation pit excavation was analyzed, and a simplified finite element model was established to calculate the internal force of the segment ring structure. Moreover, the influence factors were analyzed, such as the deformation of the foundation pit retaining structure, the clearance between the foundation pit and the adjacent tunnel, and the buried depth of the tunnel. The present study suggests that the foundation pit excavation reduces the confining pressure of the adjacent shield tunnel, increases the absolute value of bending moment and shear force, and decreases the axial force at the top and bottom of the tunnel’s segment ring. With the increase in the deformation of the foundation pit’s retaining structure, the absolute value of the additional confining pressure on the adjacent tunnel increases, and the response of the bending moment to the foundation pit excavation unloading is more obvious than the variation in the confining pressure. When the buried depth of the adjacent shield tunnel is deeper than the excavation depth of the foundation pit, the influence of the excavation on the tunnel will be obviously weakened. With the decrease in the distance between the pit and tunnel, the influence of the excavation on the tunnel will be enhanced.

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.

Control of Artificial Recharge on Foundation Pit Deformation due to Dewatering

2012 ◽  
Vol 594-597 ◽  
pp. 1901-1904
Author(s):  
Hua Yuan ◽  
Yan Hong
Keyword(s):  
Artificial Recharge ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deformation Control ◽  
Adjacent Building ◽  
The Difference ◽  
Prevention Method ◽  
Deep Foundation Excavation ◽  
Controlling Measures ◽  
Control Principle

In this paper, the currently available, feasible controlling measures for the deformation of foundation excavation and its surrounding environment are summarized systemically, which is mainly embodied in pit collapse, adjacent building differential settlement as well as underground pipeline cracking. Then first from the two aspects: artificial recharge used as prevention method and management measure separately, the paper illustrates the control principle, operation method and matters needing attention during artificial recharge. In addition, the difference between pumping well and recharge well are discusses. The research results will provide direction for the deformation control of deep foundation excavation and the operation of artificial recharge.

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.

Analysis about Bending Moment of Sheet Piles Retaining Structure

2014 ◽  
Vol 1051 ◽  
pp. 701-705
Author(s):  
Xiong Xia ◽  
Lin Lin Li ◽  
Yi Huang ◽  
Han Dong Xu ◽  
Sai Ying Xi
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
Special Device ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Retaining Structure ◽  
Surcharge Loading ◽  
Supporting Effect ◽  
Pile Group Effect

With the development of urban construction, lots of deep foundation pits have come forth continuously. As a new support structure for foundation pit, sheet piles is used in-situ due to its rigidity of pile body, but the mechanism of pile-soil interaction of sheet piles is still unclear. In order to study the bending moment behavior of sheet piles under different excavation situations and surcharge loading, the special device was designed and a series of model tests were conducted to investigate the effects of sheet piles retaining structure. The result indicates that sheet piles bending moment increases with excavations and loadings, but decreases after reaching 30 cm. bending moments are different in different positions, the deformation and moment in middle pile is the largest. Pile bending moment increases when piles spacing increases, for attenuating the pile group effect, pile-soil interaction of sheet piles can be used effectively when piles spacing is 5cm, and the supporting effect is ensured.

scholarly journals Investigation of the Axial Force Compensation and Deformation Control Effect of Servo Steel Struts in a Deep Foundation Pit Excavation in Soft Clay

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Honggui Di ◽  
Huiji Guo ◽  
Shunhua Zhou ◽  
Jinming Chen ◽  
Lu Wen
Keyword(s):  
Axial Force ◽  
Soft Soil ◽  
Control Effect ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Deformation Control ◽  
Retaining Structure ◽  
Hydraulic Servo ◽  
Ordinary Steel

This study presents a comparative analysis of the deformation control effect of the hydraulic servo steel struts and ordinary steel struts of a foundation pit based on the measured axial force of the steel struts, lateral wall deflection, and ground surface settlement due to pit excavation. The results indicate that ordinary steel struts installed via axial preloading exhibit a disadvantageous axial force loss with a maximum value equal to 86.7% of the axial preloading force. When compared with ordinary steel struts, the hydraulic servo steel strut exhibits a superior supporting effect. The hydraulic servo steel strut adjusts the axial force in real time based on the deformation of the retaining structure and the axial force of the struts. Thus, the ratio of maximum lateral deflection to the excavation depth of a deep foundation pit in soft soil is less than 0.3%. Concrete struts undergo unsupported exposure during the excavation process, leading to sharply increasing deformation of the retaining structure. Therefore, regarding a foundation pit with strict requirements for deformation control, the use of hydraulic servo steel struts rather than concrete struts is recommended.

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.

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