Performance of the Underpinning Piles for Basement-Supplementing Retrofit of a Constructed Building

Self Cite

The mechanism of drilling borehole and its influence on the bearing behavior of existing foundation piles are unclear, hindering the application of excavation techniques. This paper proposes a new excavation scheme for high-rise buildings in downtown and develops theoretical formulas to calculate the skin friction and end resistance of existing foundation piles affected by adjacent borehole drilling for installing underpinning piles. These underpinning piles are installed and connected with the existing pile by the head cap before excavation. In a case study, the parameter analysis was then performed to understand the effect of underpinning construction on the bearing behavior of existing foundation piles in terms of skin friction and end resistance. The results show that borehole diameter, depth of drilling borehole, distance between the existing foundation pile and drilling borehole, and number of boreholes have a negligible influence on the end resistance of existing foundation piles. The effect of drilling parameters on the skin friction of existing foundation pile, as well as the influence extent, varies for different parameters. The depth of drilling borehole and the number of boreholes have significant influence and thus should be considered in real engineering design while the borehole diameter and the pile-pile distance have a negligible effect. The proposed new excavation technique could be potentially adopted for real engineering design of underneath excavation projects for high-rise buildings in downtown.

Section: Drilling Borehole Diametermentioning

confidence: 99%

“…Wen et al [3] proposed the deformation control techniques for excavation beneath existing buildings. Simpson and Vardanega [4] and Shan et al [5] monitored the whole construction process of British Library excavation and the No. 3 subsection of Ganshuixiang Construction Project, respectively.…”

Section: Introductionmentioning

confidence: 99%

Influence of Underpinning Pile Drilling Construction on the Bearing Behavior of Existing Loaded Foundation Piles: Case Study

Shan

Xia

et al. 2020

Self Cite

“…Han and Ye systematically investigated the load transfer mechanism during the connection of micropiles to the concrete plate under initial load [15,16]. e behavior of underpinning piles was found based on a real case in China, which included axial-loading and excavation-unloading responses of piles [17].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Stability Analysis of a Structure during Excavation beneath This Structure

Miao

Bao-xian

Liu

et al. 2020

In order to create more underground space, it was important to investigate the impact of excavation on the preexisting building. In this paper, a scale model test was conducted to analyze the stability of the structure during excavation. The model consisted of underpinning piles preinstalled in clay, with a reinforced concrete building placed on underpinning piles. The strain and settlement of the structure were observed to reveal the time settlement of columns and the time strain of beams, columns, and piles during excavation. The results showed that the strain change of beams was small, and strain values of columns were getting higher. And underpinning piles had great strain variations. They were of great significance to underpinning design and engineering practice.

“…Pile underpinning technology can not only effectively protect existing buildings but also solve the problems of urban transportation and underground space construction [1][2][3][4][5][6]. In the process of strengthening the early Winchester Cathedral, the submersible workers used the underwater digging technology to reach the gravel layer after crossing peat and silt and then filled it with concrete to carry out the underpinning construction [7].…”

Section: Introductionmentioning

confidence: 99%

“…e reasons for the deviation are that the actual stirrup spacing is less than the design value and the vertical in ll steel bar is located at the connecting parts of new and old concrete. In order to further verify the correctness of the theoretical formula proposed in this paper, the experimental parameters of the literature [22] are taken into formulas (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15), and the theoretical and experimental comparison is shown in Table 6.…”

mentioning

confidence: 99%

Experimental and Application Study on Underpinning Engineering of Bridge Pile Foundation

Liu

Wang

Chen

et al. 2018

In order to study the theory and application of the pile foundation underpinning technology, 3 local node models of underpinning structures with a similarity ratio of 1/1 were made and the progressive repeated static loading tests were conducted. The shear and antislip properties of the joint are studied, and the improved formula for calculating the shear capacity is proposed. The results show that a planting bar plays a major role in shear resistance, and the hoop rate can improve the shear capacity of the interface. The new formula for calculating the shear-bearing capacity is proposed, and the calculation results of the formula of shear-bearing capacity are in good agreement with the experiment results. It is completely feasible to use this formula to calculate the shear-bearing capacity of the pile foundation underpinning structure. During the test, the bearing capacity of the model is good, which proves the reliability of the underpinning technology is good, and it can provide experimental and theoretical basis for the underpinning of similar projects.