scholarly journals MECHANICAL PERFORMANCE OF COMPOSITE RETAINING AND PROTECTION STRUCTURE FOR SUPER LARGE AND DEEP FOUNDATION EXCAVATIONS

2019 ◽  
Vol 25 (5) ◽  
pp. 431-440 ◽  
Author(s):  
Zhen Cui ◽  
Qimin Li ◽  
Jian Wang
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Lateral Displacement ◽  
Bending Moment ◽  
In Situ Monitoring ◽  
Diaphragm Wall ◽  
Stress System ◽  
Deep Foundation ◽  
Retaining Structure

The reliable retaining methods and a good stress system are the key to the success of super large and deep excavation engineering. In this paper, the deepest foundation pit in Hainan province is taken as an example. The method of mutual verification between in-situ monitoring and numerical simulation is adopted. The mechanical performance of composite retaining structure composed of reinforced concrete cast-in-situ soldier pile wall, diaphragm wall and prestressed anchor cable are studied. The interaction between the reinforced concrete cast-in-situ pile retaining structure at the upper part and the diaphragm wall retaining structure at the lower part is revealed, and the variation of internal forces of the diaphragm wall retaining structure in the time and space is demonstrated. And then the influence of insertion ratio and rigidity on the mechanical properties of diaphragm wall is discussed. Research shows, the range of interaction between the upper and lower retaining structures is limited. During the excavation process, the maximum bending moment of the diaphragm wall is always near the excavation surface, and the curvature of the bending moment curve decreases gradually with the increase of excavation depth and axial tension of anchor. When the insertion ratio of diaphragm wall increases, the maximum bending moment moves upward. With the rigidity of the diaphragm wall increases moderately, the bending moment of the retaining structure increases, but the lateral displacement decreases. The research results can provide theoretical basis and practical experience for the composite retaining structure design of super large and deep foundation excavations.

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.

Monitoring and Analysis on the Supporting Structure for Deep Foundation Pit

2014 ◽  
Vol 580-583 ◽  
pp. 787-790
Author(s):  
Hai Xia Sun ◽  
Ke Zhang ◽  
Si Li Chen
Keyword(s):  
In Situ Monitoring ◽  
Monitoring Data ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Metro Station ◽  
Deep Foundation Pit ◽  
Supporting Structure ◽  
Deformation Features ◽  
The Stability

This article mainly expounds the importance of in-situ monitoring on the construction process of deep foundation pit. Taking the deep foundation pit of some Shenyang metro station for example, the deformation features of the supporting structure and the internal and external of foundation pit is analyzed, according to the monitoring data of the fender pile displacement during the excavation of deep foundation pit. The conclusion is obtained that the timely and accurate in-situ monitoring information is necessary to guaranteeing construction safety. We should pay more attention to the excavation speed and exert the interior support timely during the excavation of foundation pit to avoid large deformation and danger. The analytical results of monitoring data shows that the whole stage of foundation pit excavation is stable and the fender pile with internal supports can guarantee the stability of foundation pit.

Multiprobe chloride sensor for in situ monitoring of reinforced concrete structures

2006 ◽  
Vol 28 (3) ◽  
pp. 233-236 ◽  
Author(s):  
M.F. Montemor ◽  
J.H. Alves ◽  
A.M. Simões ◽  
J.C.S. Fernandes ◽  
Z. Lourenço ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
In Situ Monitoring ◽  
Reinforced Concrete Structures

Research on Deformation Law of Deep Excavation Supporting Structures in Beijing Metro Station

2011 ◽  
Vol 243-249 ◽  
pp. 2338-2344
Author(s):  
Qing Yuan Li ◽  
Yang Wang
Keyword(s):  
Horizontal Displacement ◽  
Internal Force ◽  
In Situ Monitoring ◽  
Deep Excavation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Metro Station ◽  
Deep Foundation Pit ◽  
Deformation Law

Taking deep excavation engineering in North Region of Senlin Park Station of Beijing Olympic Subway branch as engineering background, deformation law of enclosure structure of deep excavation are studied by the in-situ monitoring means .It shows that the maximum horizontal displacement of retaining pile is closely related with excavation depth and time. When the deep foundation pit is excavated to a certain depth, and steel brace hasn’t been erected, horizontal displacement of the pile tops is maximum. The location of the maximum horizontal displacement shifts down with foundation pit excavation and steel brace erection. With steel brace application, steel axis force decrease, so steel brace can effectively control horizontal displacements of retaining pile and internal force of steel in the pile. In addition, temperature has a certain effect to axis force of steel brace.

Study on Mechanical Performance of Wall-Column Subassembly in New Precast Reinforced Concrete Frame-Shearwall Structure

2013 ◽  
Vol 351-352 ◽  
pp. 1014-1017
Author(s):  
Hao Zhang ◽  
Jia Xin Tong ◽  
Wei Jian Zhao ◽  
Chang Zheng Sun
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Kinematic Hardening ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Finite Element Software ◽  
Connection Method ◽  
Engineering Designs

A practical connection method of wall-column subassembly in new precast reinforced concrete frame-shearwall structure was proposed in this paper. Based on the general finite element software ABAQUS, numerical simulations were carried out on the mechanical performance of the precast and cast-in-situ wall-column subassemblies by using concrete damaged plastic model and bilinear kinematic hardening model. Results showed that mechanical performance of the precast wall-column subassembly, such as carrying capacities, deformations and failure modes, were almost equal to the cast-in-situ wall-column subassembly. Feasibility of the connection method which this paper proposed is verified preliminarily. The research results can provide theoretical references for related experimental researches, engineering designs and constructions.

scholarly journals Stability Control of Staged Filling Construction on Soft Subsoil Using Hyperbolic Settlement Prediction Method: A Case Study of a Tidal Flat in China

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Fei Yu ◽  
Shichang Li ◽  
Zhangjun Dai ◽  
Jian Li ◽  
Shanxiong Chen
Keyword(s):  
Tidal Flat ◽  
Lateral Displacement ◽  
Prediction Method ◽  
In Situ Monitoring ◽  
Displacement Rate ◽  
Ground Settlement ◽  
Settlement Prediction ◽  
Settlement Time ◽  
Soft Subsoil

An improved method, which combines in situ measured settlement data, hyperbolic method, and deep lateral displacement rate, is presented in this study to predict the consolidation and stability of the ground, which can be used in conducting staged filling construction on soft subsoil. A case history of a highway embankment construction in a tidal flat with thick mucky clay is studied in Xia Pu, China. Preloading with the prefabricated vertical drain method is adopted to accelerate the consolidation of a subgrade. The field behavior of soft ground under filling load is observed through in situ monitoring sensors in four typical sections. The final ground settlement in each stage is determined using the field monitoring data based on the hyperbolic settlement prediction method. For each stage of graded filling load, the ground settlement with a strain consolidation degree of 95% is defined as the standard settlement, and the corresponding settlement time is set as the standard settlement time. The preloading period is estimated according to the standard settlement time. The deep lateral displacement rate of the ground is monitored to control the stability of the foundation and recommended to guide the embankment construction. Results indicate that the presented method can predict the preloading time of graded filling, reduce the frequency of observation, and ensure the consolidation and stability of the ground.

scholarly journals Engineering Application and In-situ Monitoring Analysis of Retaining Structures of New H-section Steel Support System in Foundation Pit

2018 ◽  
Vol 53 ◽  
pp. 03080
Author(s):  
Lei Han ◽  
Min Sun ◽  
Hao Wang ◽  
Guo-xin Wang
Keyword(s):  
Reinforced Concrete ◽  
Support System ◽  
Engineering Application ◽  
Horizontal Displacement ◽  
In Situ Monitoring ◽  
Small Displacement ◽  
Foundation Pit ◽  
Support Area ◽  
The Cost

A new H-section steel support system is introduced based on a foundation pit project in Shanghai. In-situ monitoring was carried out to measure the displacement of supporting piles. The monitoring results showed that the displacement of pile-top was closely related to the excavation depth and time. It is basically no longer developing after the foundation slab concreted finished. Horizontal displacement of the pile body increased gradually with the increase of excavation depth. The maximum horizontal displacement was about 25 mm and the position was about 1 m below the bottom of the foundation pit. Finally, the horizontal displacement of the pile body was presented as a "bow" with a small displacement at two ends and a large displacement in the middle. Compared with those at reinforced concrete support area, it showed that the deformation law and final displacement value of pile-top and pile body in the new H-section steel support area was basically the same as that of reinforced concrete support area. And all of the monitoring data were within the security range, meeting the design and code requirements. Moreover, new H-section steel support system construction period was short and the cost was low. It could effectively improve the green construction level. The conclusions obtained in this paper could be referred for other familiar projects.

scholarly journals Experimental Research on Mechanical Performance of SSRC Columns under Eccentric Compression

2020 ◽  
Vol 10 (16) ◽  
pp. 5629
Author(s):  
Qingfu Li ◽  
Yihang Kuang ◽  
Wei Guo ◽  
Yanlong Zhang
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Failure Modes ◽  
Ultimate Load ◽  
Mechanical Performance ◽  
Lateral Displacement ◽  
Reinforcement Ratio ◽  
Force Characteristic ◽  
Reinforced Concrete Column ◽  
Eccentric Compression

To study the mechanical properties of stainless-steel-reinforced concrete (SSRC) columns under eccentric compression, one ordinary reinforced concrete column and eight SSRC columns were designed for eccentric compression load tests. The eccentricity and reinforcement ratio were considered as the variation parameters. The cracking and failure modes of the SSRC columns were studied. The effects of the variation parameters on the longitudinal strain, concrete strain, lateral displacement, and ultimate load were analyzed. The test results demonstrated that the failure modes of SSRC columns under eccentric compression are similar to those of ordinary reinforced columns. Eccentricity significantly affected the failure modes of the SSRC columns. Under the same eccentricity, the reinforcement ratio had negligible effect on the lateral displacement corresponding to the ultimate load. The mechanical properties of SSRC columns under small eccentric compression were better than expected; however, the ultimate loads under large eccentric compression were proposed. The ultimate load–bending moment curves obtained were consistent with the results of the test and finite element analysis. Based on the experimental results, the force characteristic coefficient was set as 2.7 for calculating the long-term crack width.

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