The application of stone column technique for improvement of soft soils has attracted a considerable attention during the last decade. However, in a very soft soil, the stone columns undergo excessive bulging, because of very low lateral confinement pressure provided by the surrounding soil. The performance of stone column can be improved by the encapsulation of stone column by geosynthetic, which acts to provide additional confinement to columns, preventing excessive bulging and column failure. In the present study, a detailed experimental study on behavior of single column is carried out by varying parameters like diameter of the stone column, length of stone column, length of geosynthetic encapsulation and stiffness of encapsulation material. In addition, finite-element analyses have been performed to access the radial deformation of stone column. The results indicate a remarkable increase in load carrying capacity due to encapsulation. The load carrying capacity of column depends very much upon the diameter of the stone column and stiffness of encapsulation material. The results show that partial encapsulation over top half of the column and fully encapsulated floating column of half the length of clay bed thickness give lower load carrying capacity than fully encapsulated end bearing column. In addition, radial deformation of stone column decreases with increasing stiffness of encapsulation material.

The study involved experimental work implemented from April 2014 until March 2017. Its purpose was to observe grape production quality parameters, such as yield, water productivity, berry size and bio-mass. Different irrigation methods, such as drip irrigation (DI), drip irrigation with plastic mulching (DIPM), drip irrigation with organic mulching (DIOM), subsur-face irrigation with stone column (SISC), subsurface irrigation with mud pot (SIMP), and subsurface irrigation with plastic bottles (SIPB) have been used during the experimental work. The crop has been irrigated following the CROPWAT-8.0 model developed by the FAO. Climate parameters are obtained from the automatic weather station located near the experi-mental field. Based on experimental results and analyses, it has been observed that the drip irrigation with the plastic mulching method is the best for irrigation in terms of the grape yield comparing with all other methods due to its highest productivity of 35–40%. Subsurface irrigation with the plastic bottle method is found to be suitable as it gives 20% higher yield than the traditional drip irrigation method. The SIPB method shows the cost-benefit ratio of 112.3, whereas the DIPM method had the ratio of 36.6. Based on the cost-benefit analysis, it is concluded that the SIPB method is economically more viable as compared with all other methods. Hence, based on the findings, it is recommended to use drip irrigation with a plastic mulch-ing and drip irrigation with a plastic bottle as the best options to achieve grape productivity while using minimum water.

The dynamic replacement columns are formed by driving a coarse-grained material into a soft soil by means of repeatable drops of a pounder. The final shapes of the columns are non-cylindrical and depend on the subsoil conditions. This paper presents results of the laboratory study on influence of the thickness of the soft soil on the displacements of the backfill aggregate during the driving process. A test box with one acrylic-glass wall was prepared, in which, over a load-bearing sand layer, a soft soil of various thicknesses (���� = 0.3, 0.4 or 0.5 m) was modelled using a semi-transparent acrylic polymer. The displacements of the backfill gravel particles were tracked by means of a high-speed camera. The material was driven by dropping a 0.2 m high (����) pounder. The results revealed that the distance between the bottom of the first crater and the top of the sand layer played an important role in directing the particles. At ����/���� = 2.5 pear-shaped floating columns were formed as the grains in the side zones were less affected by the pounder drops and their paths deviated from the vertical axis by not more than 50°. In case of ����/���� = 2.0 and 1.5, the column bases reached the bearing layer and the impact energy caused much larger vertical and horizontal displacements of the backfill material in the side zones – the observed largest angles were equal to 64° and even 90°, respectively. Eventually, the final column shapes resembled a non-symmetrical barrel and a truncated cone.