Figure 3 - uploaded by Amirhassan Mehdizadeh
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Dimensions of the test mini pile and the layout of the FBG sensors on the test pile: (a) Dimensions of grooves and the cross section of test pile; (b) layout of battered mini driven pile group with 4 and 6 piles; (c) layout of FBG sensors on the test pile (dimensions in mm)
Source publication
Improved design of vertically loaded battered pile groups can benefit various geotechnical applications, such as slope stabilisation, earth retention and bridge abutments. Current design methods rely on model pile load tests, while full-scale field tests and numerical modelling based on field results are limited. Questions still exist whether these...
Contexts in source publication
Context 1
... test mini pile is a steel, open-ended pipe pile with an outer diameter of 42.4 mm and a wall thickness of 2.6 mm. Three grooves , namely G1, G2 and G3, with 4 mm wide and 1.5 mm deep were machined along each test pile shaft ( Figure 3a) to mount FBG sensors. A groove is required as a two-part adhesive could be applied to cover the groove for harsh environment protection. ...
Context 2
... quick pile load tests were conducted for two configurations of battered mini pile groups. Figure 3b shows the layouts of the battered mini pile groups used in this study. Both pile groups utilised same dimension of steel plate which was 263 mm by 263 mm and same embedment depth of 1500 mm. . ...
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Bored piles settlement behavior under vertical loaded is the main factor that affects the design requirements of single or group of piles in soft soils. The estimation of bored pile settlement is a complicated problem because it depends upon many factors which may include ground conditions, validation of bored pile design method through testing and...
Citations
... This is despite significant differences in their interaction with surrounding soil when compared with traditional piles concerning soil block action, arching effect and a group efficiency factor of more than unity. Driven battered minipiles under uplift and compressive loading have been studied earlier (Mehdizadeh et al., 2016, Tsang et al., 2019. ...
Battered minipile groups mimicking tree root networks have been gaining popularity as a footing solution for light structural applications in residential, commercial and infrastructure sectors, recently. Battered minipile group configurations are recently in the limelight due to advantages such as ease of installation and environmentally friendly nature. The lateral load resistance of battered minipile groups is investigated in this paper through a combination of physical and numerical modelling. Two-unconventional battered minipile groups with configurations representing the root network of trees with the capacity of engaging a larger volume of soil compared to conventional battered minipile group configurations are studied. A conventional battered minipile group is also included in the study to draw a direct comparison with the new minipile group configurations introduced in this paper. The conventional battered minipile group has two positively and two negatively 25° battered minipiles. The second type of group has one 25° perpendicularly battered minipile in the leading and trailing row each. Another unique orientation of the battered minipile group is also introduced in this study which has four diagonally outward 25° battered minipiles. The third type of minipile group with four diagonally outward battered minipiles offered the highest lateral resistance among the three groups. This better performance capability was attributed to the engagement of a larger volume of soil in resisting lateral load applied at the minipile head. Through this study, the industrial application of the unconventional minipile group configuration with better performance capability in terms of lateral load resistance can be advocated more confidently.
... The minipiles studied here are hollow steel piles with a outer diameter of 42.4 mm, thickness of 2.5 mm, length of 1600 mm and they can be assumed as flexible given their slenderness (this will be corroborated later in the paper). These dimensions of the single minipiles are adopted from a system of driven battered minipile pile group [9,10]. The ultimate aim is to investigate the performance of the minipile groups under laterally loaded conditions which will be addressed in future publications. ...
... The technology has found its use in detection of failure [14] and monitoring structural health [15,16]. Optic fiber-instrumented minipiles were used to study their interaction with soil under pullout load [10] and a similar technique will be adopted in this paper. ...
... The test minipiles were instrumented with fiber Bragg grated optic fibers. One groove, which is 4 mm wide and 1.5 mm deep was machined along the length of the pile shaft [10] as depicted in Fig. 2. The optic fibers were carefully laid in the grooves and protected with adhesive. Each optic fiber consisted of 6 FBGs, spaced apart at 270 mm, thus giving measurement points at 250, 520, 790, 1060, 1330 and 1600 mm of depth from the minipile tip. ...
Driven minipile foundations are becoming common due to merits such as lightweight, easy installation and suitability for reinforcing in-situ structures with limited access. However, their interaction with the surrounding soil especially in battered conditions is not fully understood. To develop a better understanding of the interaction of minipiles with the surrounding soil, they were instrumented with Fiber Bragg grating (FBG) sensors. Open-ended steel minipiles of 1600 mm length were then driven at a site with cohesive soil vertically and at positive and negative 25˚ angle with the vertical and were tested for three in-situ lateral static loading cases. The near-continuous strain profile along the minipile shaft was reported using FBG. This helped in identifying the deformation pattern and the impact of load magnitude on this profile. The lateral load capacity was found to be maximum for positive 25˚, which decreased for 0˚, followed by negative 25˚ batter angle.
