General deformation behavior of deep excavation support systems: A review

In geotechnical engineering, ground movement caused by excavations is a challenging issue. The excessive differential settlement generated by soil movement induced by wall deflection may cause damage to nearby structures. A detailed literature review on the general deformation behavior of deep excavation support systems is presented in this paper. Many factors, such as normalized horizontal deflection (δh-max/He%), vertical displacement (δv-max/He%), δvmax/δhmax ratio, settlement influence zone (Do), etc., can play significant roles in describing the deflection behavior of the excavation system. A descriptive analysis of the reviewed data was carried out. The concluded δh-max/He% values range between 0.17 to 1.5, with a mean value of 0.58 for soft clay, while in the case of sands and stiff clay soils δh-max/He% value ranges between 0.07 to 0.40, with a mean value of 0.20. δv-max/He% values range between 0.13 to 1.10, with a mean value of 0.49 for soft soil, while its value ranges between 0.02 to 1.10, with a mean value of 0.24 in the case of sands and stiff clay soils. The settlement influence zone (Do) reaches a mean distance of 2.3He, which falls within Do=1.5-3.5He in the case of soft clays, while Do reaches a mean distance of 2.0He and 3.0He in the case of sands and other stiff clay soils, respectively. The relationship between system stiffness and excavation-induced wall and ground movements was discussed. Unfortunately, the literature review offers limited data regarding system stiffness, the 3-D nature of excavation support systems, excavation processes, and time effects.

Detection of Cracks in Clay Soil Using Quasi-3D Electrical Resistivity Tomography Method: Numerical and Experimental Study

Soil cracks affect the geotechnical characteristics of clay soils frequently used in engineered earth structures. In this work, numerical simulation and laboratory tests using Wenner- Schlumberger array of Electrical Resistivity Tomography (ERT) method are adopted to detect soil cracks in compacted clay soil. 3D numerical simulation showed that air-filled cracks have an anomalous high resistivity signature that can be differentiated from the background due to the high resistivity contrast between cracks and the surrounding soil. Depth, geometry, and extension of the simulated cracks are reasonably indicated. At the laboratory scale, quasi-3D ERT experiment was conducted. The results showed that soil resistivity is significantly affected by an artificially introduced crack as the crack forms a barrier that disturbs the flow of electricity in the soil. Similarly, depth, geometry, and extension of the crack are detected. Both numerical and experimental findings demonstrated that ERT method can effectively be used to identify cracking in clay soils. It is suggested that ERT, as a non invasive method, can be adopted with other traditional geotechnical methods for detecting cracks in clay soils.

The Dependence of Durability and Deformation of Elements of Soil Cement Composite with Carbonate White Soil Mixture on Age

The results of an experimental study of changes in strength and deformability during the period of time subjected to short-term loading of elements made of a soil-cement composite based on white soil (belozems) of carbonate composition are discussed. Research was carried out in accordance with current standards, as well as a well-known method that has been repeatedly tested earlier. To assess the experimentally established data, the results of similar studies by other authors, carried out applying elements from soil-cement based on clay soils, as well as from lightweight concrete on lithoid pumice (volcanic rock), are also presented. On the basis of the comparative analyzes of the experimentally established data, conclusions are formulated. The consideration of those may be useful both for the estimation of optimal schedules of the construction of buildings from a soil-cement composite, and for the assessment of their stress-strain state.

Bearing Capacity Modification Of Clay In The Kedungsigit Village Using Zeolite

Clay is a type of soil with a high level of water content. These properties make clay soils have a low low bearing capacity which can have an impact on the buildings above them, such as cracked walls, raised foundations, bumpy roads and so on. The soil in Kedungsigit Village, Karangan District, Trenggalek Regency is clay and needs to be repaired to build a strong building. This study aims to modify the value of the bearing capacity of clay. Modifications were made by adding Zeolite with a percentage of 0%, 5%, 10%, 15%, and 20%. Zeolite is used because it contains mineral kristal alumina silikat which have the ability to bind grains between aggregates. Observations were made on the characteristics of clay including testing of volume weight, shear strength, and bearing capacity using the Terzaghi method. The results showed the optimum value for the addition of 15. In testing the bearing capacity of the soil using the tread foundation, the value of 32,470 t/m2 was obtained for the addition of 15% zeolite and 21,376 t/m2 for the original soil. From these results it is known that the use of zeolite can increase the value of the bearing capacity of the soil. So that these modifications can be used as an effort to improve soil in Kedungsigit village.

Strength properties of biopolymer treated clay/marble powder mixtures

Depending on their unique layer structures and chemical structures, soil problems such as swelling, settlement and loss of strength can be seen especially on clay soils when exposed to water. Settlement occurring on clay soils on which the structure is built, causes various damages in the building. Additionally, in the clay soil interacting with water, strength loss occurs due to the effect of the building load. Today, when soil improvement techniques are developed and diversified, clay soils can be stabilized by using different additives. A clay soil that has been improved by adding waste marble powder within the scope of this study in certain percentages (5%, 15%, 25%), biopolymer added clay / marble powder samples were obtained by interacting with locust bean gum in certain percentages (0.5%, 1%, 1.5%). There are many studies in the literature on improving clay soils using only marble powder or only biopolymer. In this study, marble powder and biopolymer were used together and thus, the feasibility of a more effective soil improvement has been investigated. The results showed that the unconfined compressive strength of the biopolymer added clay-marble powder mixtures are higher when compared with natural clay. Similarly, shear box test results showed that the unconsolidated-undrained cohesions and internal friction angles of the doped clay samples increased. It was observed that the strength values of marble powder-added clay increased after improving with biopolymer.

Determination of Unconfined Compressive Strength and Atterberg Limit of Soft Clay by Stabilizing with Sodium Silicate and Biomass Silica in Batu Pahat

Soft clay soils can be considered as problematic soil with the characteristic of high compressibility, low permeability and low shear strength. Construction on soft clay deposit may causes problem such as insufficient bearing capacity, settlement problem and instability on excavation and embankment. Ground improvement methods were used as the aimed of this study is to determine the effect of non-traditional stabilizer on the compressive strength of soft clay soils. Therefore, the objective of this study is to determine effect of compressive strength of untreated and treated soft clay soil with addition of non-traditional stabilizer at different curing periods. The soil properties of soft clay soil such as compaction, Atterberg limits, and unconfined compression strength (UCS) testing methods were used to observe the performance of treated and untreated samples. The test results from the UCS indicated that once Biomass Silica and Sodium Silicate in the form of SH-85 and TX-85 have been added to the clay soil, the strength of the sample will increase with increasing percent of sodium silicate and curing periods.

CHANGE IN STRENGTH PARAMETERS OF DISPERSED SOILS AFTER HIGH-FREQUENCY VIBRATION

The use of the technology of high-frequency sheet piles driving or extraction in conditions of weak, structurally unstable soils inevitably leads to a change in the structure of the soil. This is especially true for buildings which fall into the zone of influence. Often, foundation for historical buildings is water-saturated sands, spread by fluid and fluid-plastic clay soils. In the process of external dynamic action, the soil foundation is been destructing, so their strength and deformation parameters are reduced. In this case, the result of vibration effects on a dispersed water-saturated sample can be both compaction for sandy soil and decompaction of clay soils. These changes lead to additional deformations of buildings and structures of the surrounding area. Therefore, the issue of assessing the limits of applicability of vibration technology in certain conditions is relevant. The object of the study is the changes in the properties of clay soils of various consistencies after exposure to vibration. The results of laboratory studies to determine the strength parameters of dispersed soils after high-frequency vibration are presented. The results of field measurements by CPT "before", "after" vibration immersion and vibration extraction of sheet piles are considered. Comparison of the results of field and laboratory studies is carried out to identify patterns of change in the strength characteristics of weak soils under the influence of vibration loads. A tendency towards a decrease in the strength parameters of dispersed soils is shown. Currently, due to the insufficient number of laboratory and field studies to study the effect of high-frequency vibration on the change in the strength parameters of weak water-saturated clay soils, it is not possible to identify a clear dependence of the change in parameters on the time and frequency of vibration.