Investigation structural settlement by Ground Penetrating Radar (Case study)

Electromagnetic wave is transferred by the GPR (ground penetrating radar), and A geotechnical application may benefit from this non-destructive test. This study is proposed to estimate the type and soil problem location that causes differential settlement of a structure (pumping station) by GPR surveying. The survey is achieved before and after the treatment by cement injection method to identify the locations that took cement injections as a full injection, partial or not at all using two types of antennas (160,450) MHz. The study also will estimate the thickness of the foundation by GPR and comparing it with actually executed. The results showed the creeping soil has occurred in some parts of the soil under the foundation, and after soil treatment, most of these parts were taken injection, and others did not. Also, it was found the relatively high accuracy of GPR for detecting the thickness of the raft foundation.

Research on Mechanical Response of Pavement Structure to Differential Settlement of Subgrade on Highway Widening

Based on the widening project of Ri-Lan highway in China, the finite element model is established by PLAXIS. By applying differential settlement at the bottom of the pavement, the mechanical response of the pavement structure is analysed. Finally, the differential settlement control standard indicated by crack strength is proposed. The results show that, under the effect of differential settlement, within about 4 cm of old pavement surface and upper base bear tensile stress, the base first reaches the failure strength. Under 4 cm of the old pavement surface, the subbase first reaches the failure strength. The differential settlement control standard of the pavement structure is determined by the splitting strength of the material, and we, respectively, control the differential settlement of less than 23.4 mm, where the corresponding cross-slope rate is 0.33%, and below 75.2 mm, where the corresponding cross-slope rate is 0.54%. It could support practical engineering applications.

Response of multistory steel structure subjected to differential settlements of its foundation

PurposeThis article aims to address an outstanding problem dealing with the structure and its foundation.Design/methodology/approachDifferential settlement between foundation units of a multistory structure has been responsible for serious damage to buildings and often catastrophic failure and loss of life. The dynamic changes in the loading conditions of the structure, and the variability of the underlying ground due to environmental changes, are causing the undesirable differential settlement, which is manifested in the form of additional stresses in beams, columns and distortion of the structure elements. The structural response to the differential settlements depends on the type of the structure (concrete or steel), type of beam-to-column connections (rigid or semi-rigid), number of floors and the spans of the beams in the building. This paper presents the results of a numerical model, which was developed using the finite element technique and the software “ABAQUS” to analyze a nine-floor steel structure. The model was capable to capture the stresses and the strains developed in beams and columns and the relationships of moment–settlement and rotation–settlement for the structural during the differential settlement of its foundation. After validating of the model, data were produced for a wide range of governing parameters for rigid and semi-rigid connections and accordingly the mode of failure. The results can be used as a guideline for the design of steel structures.FindingsResults are useful for those design steel structures.Research limitations/implicationsThis study is based on the experimental and numerical data of the authors.Practical implicationsThis study provides a guideline for the design of steel structures.Originality/valueThis is the original research developed by the authors.

Evaluating the Behavior of Embankments after Widening considering Soil Consolidation and Splicing Mode

Increased traffic volume has made it necessary to increase highway capacities by widening embankments and pavements. Differential settlement of foundation consolidation and rational utilization of existing embankments are the main problems encountered in road reconstruction. In this paper, the finite difference method is used to simulate the construction process of using the existing embankments directly in the reconstruction project of expressway, and the fluid-solid coupling model of foundation settlement is established to calculate the differential settlement between foundation and subgrade. The influence of road widening mode and embankment height on differential settlement is analyzed. The mechanical response of subgrade under differential settlement is simulated and the law of uneven settlement of main reconstruction forms is investigated. The dynamic response of existing embankments soil under the action of rammer is systematically evaluated. The results show that, with the increase of consolidation time, the differential settlement is gradually obvious at the junction of the new and existing embankments, and there is a possibility of landslide along the junction of new embankments, which should be dealt with in engineering. The smaller the height difference between the existing foundation and the new foundation is, the more the position of the maximum settlement point of the foundation moves towards the new foundation. The greater the height of the new subgrade is, the greater the uneven settlement is. The criterion based on the single rammed energy and compaction stopping standard is proposed to determine the reinforcement depth of existing embankment.