Experimental Study on Physical Mechanical Properties and Microstructure of Diatomite Soil in Zhejiang Province, China

Diatomite soil is a kind of bio-siliceous soil with complex composition and special structure, the physical and mechanical properties of diatomite soil are very important for the engineering project. In this paper, the physical properties, mechanical properties, and microstructure of diatomite soil in Zhejiang Province are studied by geotechnical tests and microscopic tests from the macroscopic and microscopic perspective. The results show that: (1) The diatomite soil has special properties different from other soils, including small particle size, low specific gravity value, high liquid-plastic limit, and low compressibility, and the strength indexes c and φ of diatomite soil will decrease with an increase in soil water content; (2) in the triaxial test, when the dry density of diatomite soil increases from 1.30 g/cm3 to 1.50 g/cm3, the effective internal friction angle of diatomite soil increases from 5.6° to 14.5° and the effective cohesion increases from 30.9 kPa to 49.6 kPa. The stress–strain curve of diatomite soil changes from weak softening type to weak hardening type when the confining pressure is above 200 kPa; (3) the diatomite soil has high porosity due to its unique microstructure; it is rich in aluminum oxides and minerals, which will greatly reduce the engineering performance of diatomite soil.

Geotechnical Properties Study of Soil Bank Slopes for Shatt Al-Hilla, Middle of Iraq

The central regions of Babylon Governorate, located on the Shatt Al-Hilla, suffer from problems as the collapse and erosion of its banks, increase in sedimentation in the river, which reduces the river flow efficiency and forms meanders in the river. After the reconnaissance visit to determine the meandering sites. A detailed study of the area was carried out by drilling 6 test boreholes representing three areas (Ancient Babylon, Bata-Bridge, and Al-Khusrweya), two wells on both sides of the meander at a depth of 10m for each borehole to know soil properties, bearing capacity and consolidation, and its effect on the engineering construction. Soil samples have been taken to carry out geotechnical tests. also conducted a study of banks stability for three stations, where the cross-section was monitored by the M9 device and the height of the banks from both sides by the LEVEL device, using the Geo-Studio-2021 program with soil properties and by using Bishop method the safety factor was extracted for the three stations for erosion-prone areas. it was 3.44 in Ancient Babylon, Bata-Bridge was 1.7 and Al-Khusrweya was 1.6 Under natural conditions, the average river flow level reaches it in year respectively are 27.88, 27.74, 27.33 m, above sea level. Where all the stations were safe unless the water level increased or decreased. Also, the research reached a determination of the allowable bearing capacity reaches it before the landslide.

Experimental Investigation on the Influence of Oven-Drying on the Geotechnical Properties of Volcanic Ash-Derived Residual Soils

For thousands of years, the volcanic activity present along the Andes Mountain range has generated a large amount of pyroclastic material. As a result, around 60 percent of the soils present in Chile have a volcanic origin, of which, we can find soils derived from volcanic ash. These correspond to soils whose origin is the weathering of volcanic ash, which generates minerals such as allophane, imogolite, and halloysite. The presence of these minerals gives these soils unique geotechnical properties, such as high plasticity, low dry unit weight, and a unique internal structure. Subjecting these soils to extreme temperatures like those needed to perform standard laboratory tests produces changes in their structures, and thus in their geotechnical behavior. These changes are important to be aware of with respect to slope stability problems, embankment conformation, surface foundations, etc. In the present study, a type of soil found in Chile originating from the weathering of volcanic ash and locally named Trumao was studied. Due to its age and formation processes, the main minerals found in the soil are allophane and imogolite, and hence it belongs to the allophanic soil type. The material was studied in its natural state (undisturbed) and, after being oven-dried using common geotechnical tests, the behaviors of both samples were compared. The study shows that some properties are affected significantly by the oven-drying process, and thus it is not recommended to expose the material to high temperatures during geotechnical laboratory testing to avoid misleading results.

Study on the Influence of Sponge Road Bioretention Facility on the Stability of Subgrade Slope

With the large-scale application of sponge city facilities, the bioretention facility in urban roads will be one of the key factors affecting the safety of construction facilities in areas with abundant rainfall. In this study, by establishing a three-dimensional finite element model for numerical analysis and combining it with geotechnical tests, the effects of bioretention facility on water pressure distribution, seepage path, and slope stability under rainwater seepage conditions are proposed. In addition, this study puts forward the relationship between the parameters of the bioretention facility and the stability of the slope in combination with the effect of runoff pollution control, which provides direction and basis for the planning, design, and construction of sponge cities in road construction.

Influence of Waste Clinical Mask Fiber on Interfacial Strength Parameters

To investigate the influence of clinical mask fibers on the geotechnical properties of different interfaces. In the present study different geotechnical tests like Triaxial Shear Tests, California Bearing Ratio Tests, and split tensile strength tests were done to understand the behavior of different mix propositions containing clinical mask fiber. From the test result, it is clear that the addition of waste clinical mask fiber in different mix proportions increases the overall shear strength of the material. Also, the percentage increases in CBR value were recorded by about 40% with the addition of clinical mask fiber. In addition, from the split tensile tests results on different mix proportions, it is observed that the tensile strength value increases up to 45% to 50 % with the addition of mask fiber to respective coarser and fine grain compositions. Thus, the study confirms that clinical mask fibers have the potential to improve the geotechnical properties and can be used as fill material in different construction like retaining structures and earthen embankments.

Isolated Effect and Sensitivity of Agricultural and Industrial Waste Ca-Based Stabilizer Materials (CSMs) in Evaluating Swell Shrink Nature of Palygorskite-Rich Clays

This paper evaluates the suitability of sugarcane bagasse ash (SCBA) and waste marble dust (WMD) on the geotechnical properties of Palygorskite-rich expansive clays located in northwest Pakistan. These problematic soils exhibit undesirable characteristics which greatly affect the pavements, boundary walls, slab-on-grade members, and other civil engineering infrastructures. A series of geotechnical tests were performed on soil specimens using prescribed percentages of the aforementioned Ca-based stabilizer materials (CSMs). The investigation includes X-Ray Diffraction (XRD) Analysis, Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF) tests, and physicomechanical properties such as moisture-density relationship, Atterberg’s limits, swell pressure, and an ANN-based sensitivity analyses of overall swell pressure development. The outcomes of these experimental investigations showed that the addition of CSMs into the expansive soils increased to 4% SCBA and 10% WMD, the plasticity index reduced by 30% and 49%, the volumetric swell decreased from approximately 49% to 86% and 63%, and the swelling pressure reduction was from 189 kPa to 120 kPa and 160 kPa (about 15% and 36%), respectively. It is interesting to note that replacement with specified CSM accelerated the strength of soil at extended curing periods and the optimum improvement in the strength behavior of the soil was also recorded. Moreover, with addition of the respective CSMs, the compactability and strength characteristics were ameliorated, while plasticity was significantly lowered. Given the amount of SCBA and WMD produced annually, their utilization for the stabilization of problematic soils, even in relatively low concentrations, could potentially have a substantial impact on the sustainable reuse of these waste materials.

Experimental Study of the Engineering Mechanical Properties of the Foundation Soil for Offshore Wind Power Platforms

Most of the coastal beach zone in the world is rich in wind energy reserves and has great potential for offshore wind power development. However, the sedimentary environment in the coastal area is complex and changeable, and the nature of the foundation soil of offshore wind power platforms is weak and complex, which is quite different from that in the land areas. In order to systematically study the mechanical properties of marine foundation soils, a series of geotechnical tests are carried out on representative undisturbed seabed soils, such as basic laboratory geotechnical tests, bender element tests, undrained triaxial shear tests, and resonance column tests. The test results show that shear wave velocity (Vs) of marine silt and silty clay increases linearly with the buried depth; the stress-strain relationship curves of silty clay and silt present two different modes of development: strain hardening and strain softening, the undrained shear strength (Sd) of the two types of marine soils decreases with the increase of the void ratio (e), and both present a good single correlation. Based on the relationship between Sd and Vs from the laboratory test of disturbed seabed soils, an undrained strength evaluation method of undisturbed seabed soils under the current stratum conditions incorporating in situ shear wave velocity is established. The dynamic shear modulus (G) in the various strain ranges of undisturbed silty clay and silt increases regularly with the buried depth (H). Meanwhile, the maximum dynamic shear modulus (Gmax) linearly increases with the increase of H, whereas the attenuation relationship of G decreases with the increase of H. The prediction method of G based on buried depth is established with high accuracy.

Water Table Effects on the Behaviors of the Reinforced Marine Soil-footing System

This study evaluates the effects of a water table on the behaviors of a geogrid reinforced soil-footing system on marine soft soil layers in Qeshm Island, Iran. The main aim of this research is to recommend the optimum specification of the reinforced soil-footing system. A series of geotechnical tests were adopted to measure the properties of the soil profile. The impacts of the water table and the geogrid layer specifications were evaluated by the finite element analysis to investigate the system’s behaviors. Finally, the optimal reinforced soil-footing is suggested. Doi: 10.28991/HEF-2021-02-03-09 Full Text: PDF

The Use of 3D Numerical Modeling in Conceptual Design: A Case Study

This article describes the construction of a building with four aboveground floors and one underground floor as part of the ongoing development of Warsaw’s city center. A 3D numerical model was developed to reflect the spatial and structural solutions of the new building based on the design documentation with regard to the outcomes of geotechnical tests, the actual phases of work completed, the results of the geodetic measurements carried out in individual phases of the building implementation, and the characteristics of the existing adjacent buildings. The 3D numerical model was calibrated taking into account the results of the geodetic measurements of the benchmarks stabilized on the adjacent buildings. The numerical models of the building were used to analyze a number of multiple-step variants, taking into account the increase in the number of aboveground floors (from 1 to 4) and underground floors (by 1), as well as the increase in the projected area of the underground part compared to the area of the site designated for development. The paper presents the conclusions of our analyses, which may be helpful to others designing buildings in intensively urbanized areas and guide them in selecting the best solution.

Effect of pile driving on ground vibration in clay soil: Numerical and experimental study

In this study, peak particle velocity (PPV) values for driving three piles with 40 cm, 50 cm, and 70 cm in a clayey soil through the impact piling method are investigated by an experimental study and a numerical simulation. An experimental study is carried out on a scale of 1:20 of the operation. Numerical simulation is performed by using an axisymmetric model in PLAXIS 2D finite element software. Properties of the soil and the piles used in the experimental study are obtained from geotechnical tests and employed in the numerical simulation. The model has been verified by comparing the acquired PPV values with those measured in the experimental study. The results show a good agreement between the computed values and the field data. Moreover, measured peak particle velocities in the experimental study indicate that an increase in the diameter of the pile can increase the level of ground vibration. Some sensitivity analyses have been performed by numerical modeling to determine the effect of soil and pile properties on the changes of PPV. The results indicate that increase in friction angle of the soil and pile diameter and reduction in elastic modulus of soil will increase the level of ground vibration.