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Due to congestion in overground space, many underground structures have been built to facilitate communications between cities. These structures constructions will induce soil displacement, cities planning rearrangement,
and sometimes are near to future buildings constructions. In some cases, communication channels should be built
to allow the unde...
Contexts in source publication
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... foundation pit of Baoneng T7&MALL project is located on the southeast side of the intersection of Yungu Road and Yinzhou Avenue in Binhu New District of Hefei City. The foundation pit protection was completed in 2015 (status od foundation pit now Fig. 2). It has passed the design and has been used for field investigation. The foundation pit retaining structure is damaged to varying degrees, and the foundation pit must be re-reinforced. A new underground connecting section is connected to the entrance and exit of No. 2 Yungu Road Station of Metro Line 1. Yungu Road Station of Metro ...
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... it will condition the subway tunnel displacement reduction. Similar results ware obtain by Seo [32]. As the bottom supports (struts or anchors) were removed to build the underground structure, additional surface settlement and inward bulging of the wall occurred. However, vertical tunnel displacement is more important in case 1 than case 2 (Fig. 22). In case 1, Installing the retaining walls reduce the horizontal soil displacement this will generate vertical forces due to the pressure induced by the contact between the walls and the soil. These verticals forces will make additional vertical displacement of the surrounding soil near to the ...
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... first part of this section will focus on different walls thicknesses effects on the displacement of the exit structure. Fig. 23 shows the lateral outward (direction toward the excavation pit) exit structure decreases due to the augmentation of the thickness of the walls. Similar results were presented by Hashash [33]. Increasing system stiffness and embedment of the wall into a stiff layer are essential factors in limiting the deformations. However, the lateral ...
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... vertical displacement of the exit structure increase with the thickness of the walls increasing (Fig. 24). Aforementioned is due to the augmentation of the wall weight that intends to move downwards the soil around it, by the way, the subway ...
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... struts had been model like beam element. The shape is a rectangle (width*height). This part focus on the exit structure displacement behavior looking at differents struts cross sections. The lateral displacement variation is not remarkable in both (Fig. 25). This show that the walls thickness variation as much necessary rules in the variation of the exit structure lateral structure than the struts. Fig. 26 shows the exit structure vertical displacement increase with the struts crosses section increases. However, the variation evolution is less important compate to the one obtained from ...
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... a rectangle (width*height). This part focus on the exit structure displacement behavior looking at differents struts cross sections. The lateral displacement variation is not remarkable in both (Fig. 25). This show that the walls thickness variation as much necessary rules in the variation of the exit structure lateral structure than the struts. Fig. 26 shows the exit structure vertical displacement increase with the struts crosses section increases. However, the variation evolution is less important compate to the one obtained from the walls thickness ...
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... piles cross section had been model as a circle. This section studies the exit structure displacement looking at different piles diameter. Fig. 27. Shows the lateral outward exit structure decrease with the pile's diameter increase. However, unpredictable behavior is observed on the lateral outward exit structure displacement. Significant effects variations in noticed on the vertical exit structure displacement (Fig. 28). The vertical displacement increase with the augmentation ...
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... the exit structure displacement looking at different piles diameter. Fig. 27. Shows the lateral outward exit structure decrease with the pile's diameter increase. However, unpredictable behavior is observed on the lateral outward exit structure displacement. Significant effects variations in noticed on the vertical exit structure displacement (Fig. 28). The vertical displacement increase with the augmentation of the pile's ...
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... foundation pit of Baoneng T7&MALL project is located on the southeast side of the intersection of Yungu Road and Yinzhou Avenue in Binhu New District of Hefei City. The foundation pit protection was completed in 2015 (status od foundation pit now Fig. 2). It has passed the design and has been used for field investigation. The foundation pit retaining structure is damaged to varying degrees, and the foundation pit must be re-reinforced. A new underground connecting section is connected to the entrance and exit of No. 2 Yungu Road Station of Metro Line 1. Yungu Road Station of Metro ...
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... it will condition the subway tunnel displacement reduction. Similar results ware obtain by Seo [32]. As the bottom supports (struts or anchors) were removed to build the underground structure, additional surface settlement and inward bulging of the wall occurred. However, vertical tunnel displacement is more important in case 1 than case 2 (Fig. 22). In case 1, Installing the retaining walls reduce the horizontal soil displacement this will generate vertical forces due to the pressure induced by the contact between the walls and the soil. These verticals forces will make additional vertical displacement of the surrounding soil near to the ...
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... first part of this section will focus on different walls thicknesses effects on the displacement of the exit structure. Fig. 23 shows the lateral outward (direction toward the excavation pit) exit structure decreases due to the augmentation of the thickness of the walls. Similar results were presented by Hashash [33]. Increasing system stiffness and embedment of the wall into a stiff layer are essential factors in limiting the deformations. However, the lateral ...
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... vertical displacement of the exit structure increase with the thickness of the walls increasing (Fig. 24). Aforementioned is due to the augmentation of the wall weight that intends to move downwards the soil around it, by the way, the subway ...
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... struts had been model like beam element. The shape is a rectangle (width*height). This part focus on the exit structure displacement behavior looking at differents struts cross sections. The lateral displacement variation is not remarkable in both (Fig. 25). This show that the walls thickness variation as much necessary rules in the variation of the exit structure lateral structure than the struts. Fig. 26 shows the exit structure vertical displacement increase with the struts crosses section increases. However, the variation evolution is less important compate to the one obtained from ...
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... a rectangle (width*height). This part focus on the exit structure displacement behavior looking at differents struts cross sections. The lateral displacement variation is not remarkable in both (Fig. 25). This show that the walls thickness variation as much necessary rules in the variation of the exit structure lateral structure than the struts. Fig. 26 shows the exit structure vertical displacement increase with the struts crosses section increases. However, the variation evolution is less important compate to the one obtained from the walls thickness ...
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... piles cross section had been model as a circle. This section studies the exit structure displacement looking at different piles diameter. Fig. 27. Shows the lateral outward exit structure decrease with the pile's diameter increase. However, unpredictable behavior is observed on the lateral outward exit structure displacement. Significant effects variations in noticed on the vertical exit structure displacement (Fig. 28). The vertical displacement increase with the augmentation ...
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... the exit structure displacement looking at different piles diameter. Fig. 27. Shows the lateral outward exit structure decrease with the pile's diameter increase. However, unpredictable behavior is observed on the lateral outward exit structure displacement. Significant effects variations in noticed on the vertical exit structure displacement (Fig. 28). The vertical displacement increase with the augmentation of the pile's ...
Citations
... This gap has resulted in an underground environment that consists of an intricate web of many underground pipelines, subway tunnels, underground parking lots, underground commercial streets, and building foundations. This complex underground construction has led to the development of large, tight and deep foundation pits, which pose major challenges for their excavation and support in narrow spaces (Westermann et al. 2020;Deng et al. 2023;Fall et al. 2019). Moreover, the high energy consumption and high carbon emissions of foundation pit projects have serious adverse effects on global warming (Bowerman et al. 2011;Tang et al. 2017;Won et al. 2019). ...
The goal of this study is to promote the development of high-quality energy and emission reduction measures for super large deep foundation pits applied in metro system construction projects in areas with loess. In this paper, Rhinoceros 6 is first used to model the super large deep foundation pit on both sides of the existing subway. Second, the Mohr‒Coulomb model and the elastic model are used for numerical calculations in FLAC 3D. In-depth analysis of the deformation of the foundation pit and its surrounding environment and optimization of the support system are performed from the perspectives of safety, economy and environmental protection. Finally, the emission factor method is used to analyze the energy consumption level of the support system. The results reveal that the surface settlement, horizontal displacement of support structure, and horizontal and vertical displacements of the lining increase with the number of construction stages (CONS). In addition, there are strong and stable areas of ground settlement. The ground settlement in the strong area exhibits a V-shaped trend. The horizontal displacement of the lining structure is concentrated in the lower 1/5 of the lining structure, and the vertical displacement gradually decreases from the center toward the east and west. Increases in the pile diameter and diagonal steel support stiffness significantly reduce the deformation of the super large deep foundation pit excavation on its sidewalls and surroundings. The optimized support system greatly reduces the project cost and construction difficulty, and the total carbon emissions are reduced by 27.52%.
... To model the behavior of the soil medium properly, the Mohr-Coulomb criteria was used in this study. The Mohr-Coulomb model requires only a few parameters [14]. The pile cap, the dual-row piles, the counterfort retaining wall, the backfill concrete, and the soil were modeled by solid elements. ...
... The backfill process is completed in 10 times. The following formula is adopted to generate the initial ground stress [14]: The horizontal displacement contour of Case 1 after backfilling is shown in Figure 6. The maximum horizontal displacement is 43.6mm, and the maximum horizontal displacement is located near the pile caps of double-row piles. ...
With the increase of the height of the filled slope, the application of multiple combination retaining structures (MCRS) is becoming more and more popular. However, the traditional design methods seldom consider the coupling effects between the substructures. To investigate the interaction of MCRS, this paper takes the filled slope project of a middle school in Quanzhou City, Fujian Province, China as an example. The filled slope was supported by MCRS, including reinforced soil, doublerow piles, anchors and counterfort retaining walls. The simulate procedure mainly included the following process: first, the MCRS model was established, then the mechanical response of the MCRS when replacing the fill materials and increasing the length of the rear row piles were obtained, and a comparative analysis was carried out. The following conclusions could be drawn: (1) The properties of backfill material have a significant impact on the displacement of backfill slope, and when the backfill is gravel soil, the displacement of slope can be controlled to a satisfactory degree. When the back-fill soil is replaced by silty clay, the shear strength and internal friction angle of soil become smaller, thus the displacement of slope increases significantly, which may lead to slope failure. (2) When the anchorage length is satisfied, increasing the length of the rear row pile has no significant effect on reducing the displacement of MCRS slope, but it can effectively reduce the axial force of anchor rod. (3) In MCRS, each substructure has complex interaction, and numerical simulation provides an effective means for accurate evaluation of MCRS.
... Thus, the effects of the soil between the two rows of piles were neglected. Fall et al. [28] proposed a case of DR sheet pile wall in deep foundation pits. The numerical and field test results demonstrated that the deformation of the DR sheet pile wall is relatively small. ...
The traditional pile design method of dual-row pile wall (DRPW) occasionally considers the effect of flexural stiffness ratio between front row (FR) to rear row (RR). DRPW can no longer satisfy the requirements of settlement and deformation for substantial digging depth. This study evaluated the influence of flexural stiffness on DRPW and proposed an optimization method, namely, variable stiffness technology. Two optimal types of DRPW, namely DRPW with enlarged section of FR and that with enlarged section of RR, were compared to the traditional equal-section DRPW. The effects of flexural stiffness ratio, excavation depth, and surcharge loading were investigated in this study using physical scale test and finite-difference method. The model piles were instrumented with strain gauges and dial meters to measure the bending moment and deflection, respectively. The three types of DRPW have the same volume, height, sum of cross-section area, and material. Favorable consistency was observed between the numerical simulation and model test. Overall, the flexural rigidity ratio of FR to RR has a remarkably impact on the mechanical property of DRPW; thus, increasing the stiffness of the front pile is effective. The three types of pile arrangement are ranked as follows: the DRPW with enlarged section of front pile > the DRPW with enlarged section of rear pile > the traditional equal-section DRPW.
... Taking building information modelling (BIM) as the risk identification platform, Ganbat et al. [12] set up a mechanism that can identify the risks accurately and timely in the early stage of construction. With the aid of engineering software [13][14][15] simulated how excavating deep foundation pit disturbs the soil and affects the displacement of underground pipelines, and introduced additional reinforcement to the hazardous areas [16,17] regarded tunneling risk as the equivalent of excavating risk of foundation pit, designed reinforcement measures against instability and deformation, and successfully applied the measures in metro station construction. In addition, the FCE results on the safety of buildings near deep foundation pits [18] are widely used in engineering. ...
The construction of modern city consists of many underground facilities, and one major concern is how to construct them safely and efficiently. Thus, the excavation-induced pile response needs to be evaluated. Dual-row batter pile wall (DRBPW) exhibits better performance than traditional dual-row vertical pile wall (DRVPW) in foundation pit engineering. However, the study of single pile subjected to excavation-induced soil movement behind DRVPW is rather limited, needless to say that of the DRBPW. An explicit finite difference method (FDM) was utilized to obtain the responses of isolated floating single pile (IFSP) near deep excavations braced by DRBPW. The responses of IFSP in the vicinity of foundation pit reinforced by DRBPW were compared to that of the DRVPW. The pile length, distance of pile from wall, excavation depth, working load, and Young’s modulus of pile were considered in the parametric study. The conclusions were as follows: (1) The DRBPW can minimize the influence on the existing pile; thus, the induced lateral displacement and bending moment of pile retained by DRBPW are smaller than that of DRVPW. (2) The excavation depth, pile location, and pile length have significant influence on the responses of IFSP adjacent excavation, while the working load and Young’s modulus of pile have diminutive influence. (3) The influence zone induced by excavation can be divided into two areas. The primary influence zone is the severely affected area where the induced deformation and bending moment are remarkable. The secondary influence zone is the moderately affected area where the induced deformation and bending moment are mild. The primary influence zone is within twice of the excavation depth. The secondary influence zone is 2.0–3.0 times that of the excavation depth. (4) The pile toe of IFSP has considerable lateral displacement during excavation, and attentions should be paid to the whole pile shaft during construction.
To evaluate the performance of dual-row batter pile wall (DRBPW) in deep excavations, a three-dimensional numerical model was established. The plastic hardening (PH) constitutive model in FLAC3D was adopted, considering the hardening property of the soil. A series of parametric study was conducted to investigate the effect of different factors. By analyzing the maximum lateral displacement, the pile shaft deflection and bending moment of both the leading and trailing row, the effect of inclination angle, pile diameter, penetration depth, and row spacing on the behavior of DRBPW was determined. The following conclusions could be drawn: (1) The bearing capacity of DRBPW is quite larger than that of the dual-row vertical pile wall (DRVPW). With the increase of inclination angle, a substantial reduction of lateral displacement could be observed. However, the beneficial role of batter pile is almost negligible when the inclination angle is not larger than 5°. The recommended inclination degree of the batter pile is 10° to 15°. (2) The maximum displacement of the leading and trailing rows lies at a distance below the pile cap, while the maximum bending moment is located at a small distance below the dredging line. The maximum bending moment of the leading pile is approximately twice that of the trailing one, thereby indicating that the leading pile bear more lateral earth pressure than the trailing pile. (3) The pile diameter, penetration depth and row spacing should be maintained in a suitable range; otherwise, the DRBPW may fail earlier than expected. The slender ratios is recommend to be set not larger than 30. The penetration ratio should not be less than 0.22. The optimal row spacing for the DRBPW is four times the diameter.
A method for predicting deformation during the excavation of a foundation pit in composite formation is proposed. The artificial bee colony algorithm (ABC) is introduced to optimize the back-propagation (BP) neural network with the input variables filtered. This method is applied to predict the deformation of a foundation pit project. The prediction results are verified by comparing the results with those of other neural network models. The results indicate that the depth of excavation, speed of excavation, friction angle in the soil, gravity, elastic modulus and number of internal support layers are the main factors affecting the deformation of the soil layer around the foundation pit. The ABC algorithm is capable of searching for better solutions of initial weights and thresholds. The ABC-BP model with a 6-12-2 network structure has high prediction accuracy and the best generalization ability.
Deep foundation pits are usually located in densely built-up areas, and its stability is affected by adjacent structures. A few studies have considered the effect of surcharge load on the stability of foundation pits; such effect may lead to excessive deformation or even collapse. To determine the mechanical response of dual-row pile walls (DRPWs) in foundation pits under the action of surcharge loading, a physical scaling model test and numerical simulation were conducted, and a method to determine the influence of overloading was provided. Five physical scaling model test schemes were proposed; electronic displacement gauges, strain gauges, and pressure sensors were installed to test the static response of a DRPW under excavation and surcharge load. The effects of loading distance and load magnitude on the bending moment, pile head displacement, and pile shaft deformation of DRPWs were also investigated. The relationship between overload and the mechanical response of DRPWs was quantified, and the results of physical model tests were verified by numerical simulation. Results showed that surcharge loading has a negative effect on the stability of DRPWs in foundation pits, and the deformation of DRPWs is negatively correlated with the loading distance of surcharge load. The critical value of the loading distance of surcharge load is 0.5 times the excavation depth. When the loading distance is less than the critical value, the overload causes remarkable displacement and inner force of the DRPW. Moreover, the deformation of the DRPW is positively correlated with the surcharge loading magnitude. With the increase in vertical loading, the displacement of soil increases nonlinearly, and the circular sliding surface through the excavation bottom is finally formed. The results of this study provide some references for the design and construction of DRPWs.
