Belled piles are increasingly being employed for transmission tower foundations in the mountainous regions of Western China, but their uplift behavior is not fully understood. This paper presents experimental investigations of the pull-out behavior of belled piles in horizontal and inclined ground (overlying soil and underlying soft rock). 3D non-linear finite element analyses related to the model tests were also conducted using ABAQUS software, and the influence of slope effect on the ultimate uplift capacity of rock-socketed belled piles was evaluated. The results demonstrated that the inclined ground led to deterioration in its uplift performance, thus increasing both the displacement of the pile cap and ground surface. When the slope angle changes between 0 degrees and 30 degrees, the weakening effect of the slope on the ultimate uplift capacity increases linearly. When the slope angle is increased to 45 degrees, the weakening effect of the slope on the ultimate uplift capacity is greatly enhanced, and the relationship between the ultimate uplift capacity of belled piles in the inclined ground and the slope angle is proposed. Moreover, the failure mode of the horizontal bedrock is an inverted cone with a failure angle between 0.8 and 1.0 phi r (phi r is the internal friction angle of bedrock). In contrast, the bedrock failure of inclined ground is bulb-shaped, and it mainly occurs within 4d (d represents pile diameter) of the downslope side. It was also discovered that the downslope side of the belled pile in the sloped ground generated cracks that directed to the pile axis if the pile top load reached 82.3% of the ultimate uplift capacity. These findings are valuable for practicing engineers in the rational design of belled piles, taking account of the weakening effect of inclined ground. Reveal the adverse effect of inclined ground on the uplift bearing deformation characteristics of the belled pile.It is clarified that the failure mode of rock-socketed belled piles in inclined ground varies with the slope angle through model test and 3D numerical method.Propose an empirical relationship to quantify the ultimate uplift capacity of rock-socketed belled piles in inclined ground and the slope angle.

Thermo -mechanical (TM) behaviour of energy pile (EP) is strongly affected by the pile constraints. The influence mechanism of different constraints on TM behaviour of EP should be revealed. In this paper, the model experiments in laboratory are carried out to research effects of pile end constraints and sand compactness on TM properties of EP. The research results display that the strain of end bearing pile increases gradually along pile depth due to the larger constraint at the pile tip, while the strain distribution of friction pile is large at both ends and small in the middle. Compared with friction pile, the end bearing pile has larger pile tip soil pressure and smaller side friction of pile. The displacement change of EP decreases during the operation in summer mode after applying 0.5 kN load on the pile top. The displacement of end bearing pile can restore to 0 mm, while the friction pile has a settlement of -0.028 mm. In winter mode, both the end bearing pile and friction pile produce unrecoverable settlement, and applying load on pile top will further aggravate the settlement amplitude. As for influence of sand compactness, compared with loose sand, the dense sand has greater thermal conductivity which benefits to the thermal efficiency of EP. This results in smaller pile excess temperature and recovery rate of surrounding soi1 temperature. Accordingly, the pile top displacement and strain also decrease due to small temperature variation, but the pile side friction and side soil pressure increase. The mechanical properties of EP under the condition of different pile -soil parameters are simulated by a 3-D numerical model, which is validated by experiments. It is shown that when the Poisson's ratio of the soil increases from 0.2 to 0.4, the top displacement of the pile increases from -7.35 mm to -8.76 mm, which attributes to the increase in the lateral deformation of the soil, resulting in a decrease in the soil constraint on the pile. Although the distributions of pile side friction along the pile depth are basically the same for different poisson's ratios, there are differences at the pile tip. Also, increasing the pile -soil interface friction coefficient will result in the enhancement of constraint and pile side friction and the decrease of pile body displacement and thus improve the mechanical properties of EP. The study helps to reveal the influence mechanism of various constraints on the TM properties of EP and can provide reference for the safe and efficient operation of EP.

The authors used the crushed coconut shell to make granular columns which were obtained from the market area of Kuantan, Pahang. The coconut was crushed into a similar size of coarse aggregate for the replacement of non-renewable resources like sand and gravel. From its general properties, a coconut shell is hard and can withstand a certain value of exerted value regardless of compression or tension. Besides, the coconut shell is an agricultural product and is found abundantly after human consumption. For this research, the stone-column method was used. The installation of a single coconut shell column was implemented through the Vibro-replacement technique on the soft clay soil. Before accessing the shear strength parameters, the evaluation of the physical and mechanical properties of coconut shells and kaolin was executed via the appropriate geotechnical laboratory approaches. The shear strength parameters were analysed with the control and reinforced specimens through the Unconfined Compression Test (UCT). For the shear strength value, the average value from 4 specimens was utilized as the final value. A total of 16 samples were constructed for all the specimens, reinforced design comprised of 13 mm column diameter, and column heights of 60 mm and 80 mm were categorized as partially penetrated columns while 100 mm was a fully penetrated column. The highest shear strength improvement was recorded when the column height was 100 mm, resulting in 28.51 %, whereas the least was recorded when 60 mm of height was constructed, only 17.28 %. Conclusively, the positive results of shear strength improvements were yielded by the utilization of coconut shells and proved that it was practical and economical.