Finite-Element Analysis of Strengthening the Subgrade on the Basis of Boring and Mixing Technology

Abstract

One of the effective techniques to strengthen the subgrade is boring and mixing technology, which is based on the immersion of vertical elements -piles into the subgrade. This method of strengthening significantly affects the stress state of the track superstructure. Two options of the placement of strengthening elements are examined in this paper. To determine the influence of position of strengthening elements on the stress state of the track superstructure, appropriate finite-element models were created. The models fully reflect the geometric and deformation characteristics of a real subgrade, which is strengthened by piles. The calculated stress state of the track superstructure is shown and analyzed in this paper. The main contribution of the paper lies in optimization of the geometric parameters of the technology to reduce the stress state of the "track superstructure-subgrade-soil basement" system. The results show that the location of piles near the rails is more effective than the location of piles near the ballast section.

Regularities of the strain state of the embankment when varying the vertical element length of strengthening

“…A finiteelement model of the embankment, its soil base, and the rail-sleeper grid has been created (figure 2). The installation of a pile with a diameter of 0.2 m in exactly this position is based on the results of the study [9], as well as on the technological capabilities of the drilling unit, which can carry out drilling without removing the rail-sleeper grid. The diameter of the pile researched within the framework of this article is considered reduced since most often the range of diameters varies between 0.3 ... 1.2 m.…”

“…An alternative option for strengthening the embankment is a type of reinforcement by immersing vertical elements (piles or micropiles) [6,7]. The idea of strengthening with piles or micropiles has been widely developed in many fields of construction [8,9]. Its implementation for the embankment is based on drilling and mixing technology or jet-grouting [6][7][8][9].…”

“…The idea of strengthening with piles or micropiles has been widely developed in many fields of construction [8,9]. Its implementation for the embankment is based on drilling and mixing technology or jet-grouting [6][7][8][9]. An important issue is the placement of vertical elements and the determination of their effective parameters.…”

“…The finite-element model of the embankment with a height of 6 m for the track gauge of 1520 mm. Strain characteristics (the elasticity modulus E) of the finite-element model are as follows: 1) rail (steel) E=2.1•10 8 kPa; 2) sleeper (ferroconcrete) E=4.0•10 7 kPa; 3) ballast (crushed stone) E=10•10 4 kPa; 4) embankment (weak clay loam) E=25•10 3 kPa; 5) pile (soil cement armored with a steel carcass) E=140•10 5 kPa.The installation of a pile with a diameter of 0.2 m in exactly this position is based on the results of the study[9], as well as on the technological capabilities of the drilling unit, which can carry out drilling without removing the rail-sleeper grid. The diameter of the pile researched within the framework of this article is considered reduced since most often the range of diameters varies between 0.3 ... 1.2 m.The model was loaded forcefully with 117.5 kN on the rail, which is half of the train load.…”

Organizational and Technological Parameters of Clay Soil Mixing Technology

“…Струменевим способом готують ґрунтобетонні елементи перетином до 2000 мм і більше, в той час як механічними -300…500 мм, що потребує їхньої додаткової кількості як заходу компенсації і тим самим додаткових витрат ресурсів та часу. При цьому в обох технологіях утворений ґрунтобетон має низькі фізико-механічні показники через завеликий вміст води як наслідок використання водонасиченої цементної емульсії та водяних струменів у відповідних технологіях (Петренко, Тютькін, Крисан, В. І., & Крисан, В. В., 2019;Tiutkin, Neduzha, & Kalivoda, 2021).…”