Analysing Allowable Horizontal Displacements of Retaining Wall Based on Limited Settlements of Adjacent Building
Quoc Thien Huynh, Huu Thoi Tra, Lindung Zalbuin Mase, Nhat Hoang Vo, and Van Qui Lai
ABSTRACT: This paper proposed and validated allowable horizontal displacements of retaining wall based on limited settlements of adjacent building with shallow foundation. The Finite Element Analysis (FEA) by Hardening Soil (HS) model was employed to verify horizontal displacements of retaining wall (δmax) and settlements of adjacent building (Uy) from seven well-documented excavation cases in Ho Chi Minh (HCM) city, Vietnam. Following the comparisons between the FEA results and field observations, a close correlation between δmax/H and Uy was proposed to δmax/H = -αUy, in which α was unit coefficient varying according to excavation depth H(m). Another case of deep excavation in Ha Noi city, Vietnam was used as a practical application to confirm the obtained results.
KEYWORDS: Deep excavation, Adjacent building, Limited settlement, Allowable displacement.
Load-Settlement Behaviour of Geotextile-Based Geocell Reinforced Sand Bed
Chirajyoti Doley, Utpal Kumar Das, and Sanjay Kumar Shukla
ABSTRACT: The potential of application of geotextile-based geocells in improvement of performance of sand foundations is investigated in this study. Model plate load tests conducted on unreinforced and geocell-reinforced sand beds have shown that the use of geocell reinforcement improved the performance of reinforced sand bed, both in terms of bearing capacity and settlement. The bearing capacity of sand bed is found to increase with an increase in reinforcement width (b); however, the benefit is observed marginal for b > 4B (B = width of footing). The results also show a maximum Improvement Factor of about 3.5 for the relative density of 35%, and about 2.4 and 1.9 for the relative density of 70% and 90%, respectively, at s/B = 10%, b/B = 3 (s = settlement of footing). Further, it is found that provision of geocell reinforcement almost arrests the surface heaving of soil, irrespective of the relative density of sand bed.
KEYWORDS: Geocell reinforcement, Relative density, Bearing capacity, Improvement factor, Surface heaving.
Influence of Moisture Content on Tropical Slope Soils
Bruno Cavalcante Mota and Francisco Heber Lacerda de Oliveira
ABSTRACT: This paper aims to analyze the influence of subgrade moisture variation on the structural performance of a road section, through deflectometric data, in dry and post-rainy periods. For the sections analyzed, it was found that the rainy period resulted in increased by 4.53% of the subgrade moisture, causing variations of up to 25.60% in deflection data in mixed section. For the embankment and cut sections, the influence of moisture was negligible, given the efficiency of the drainage system. It was also possible to observe that, when the ground and pavement elevations are relatively equal, the water table directly affects the subgrade, preventing accurate analysis of the rainy period with relation to deflection. Thus, it is evident the need to implement drainage devices that allow the reduction of the impact of moisture variation on the structural performance of a pavement, enabling the maintenance of its service life.
KEYWORDS: Pavements, Deflection, Drainage, Soil plasticity, Variation of moisture.
Shear Strength of Earth Materials in a Weathering Profile Over Granite
John Kuna Raj
ABSTRACT: The weathering profile can be separated into an upper, 11.8 m thick pedological soil (zone I) comprising gravelly clayey sands and a lower, 31.9 m thick saprock (zone II) of silty gravelly sands that distinctly preserve the minerals, textures and structures of the original granite. Consolidated drained triaxial tests on five sets of undisturbed samples from sub-zones IC2 (set A), IIB (set B), IIC (set C) and IID (sets D and E) yield effective cohesions (c’) of 34.4 kPa, 22.7 kPa, 24.7 kPa, 27.2 kPa, and 14.5 kPa, and friction angles (φ’) of 30.7o, 33.5o, 31.5o, 32.5o, and 34.4o, respectively. Regression analyses show the effective cohesion of samples from sub-zones IIC and IID to decrease with increasing moisture contents retained at 33 kPa, and 1,500 kPa, suction pressures; features indicating the decreasing influence of capillary and sorptive forces, respectively.
KEYWORDS: Consolidated drained triaxial tests, Effective cohesion and friction angle, Matric suction.
Flexible Piles within MSE Retaining Wall System
Salah Mahdi Hamza, Shaymaa T. Kadhim, and Saad F. A. Al-Wakel
ABSTRACT: In bridges, pile foundations carry the lateral loads created by the movement of the abutment deck. Due to the limited space, retaining walls constructed of mechanically stabilized earth (MSE) may be constructed on the abutment face. In contrast to conventional design methodologies for MSE retaining walls and piles, the effect of pile-wall interaction must be thoroughly investigated. The effects of several variables on the behavior of a flexible pile subjected to lateral loading and located behind an MSE retaining wall system in loose and dense sand soils are discussed in this study. These variables include the offset of the piles, the slenderness ratio, the soil density, the length of reinforcement, and the type of connection between the reinforcing units and the wall facing. The results indicated that when flexible piles are installed closer to the MSE retaining wall, their lateral capacity is significantly reduced. In comparison to the frictional connection model, the mechanical connection between BRC wire mesh and wall facing exhibited better performance of flexible piles in terms of lateral capacity.
KEYWORDS: Retaining wall, Pile, Lateral resistance.
