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Experimental study on dynamic consolidation method to improve saturated soft soil foundation
Published in Mohd Johari Mohd Yusof, Junwen Zhang, Advances in Civil Engineering: Structural Seismic Resistance, Monitoring and Detection, 2023
Haolan Wang, Ying Wang, Jinglin You, Shijie Wang
Considering that the soft soil layer has a long thixotropic solidification stage after dynamic compaction, the detection work is carried out 15 days after the end of dynamic compaction. The size of the bearing plate in the load test is 1m × 1m, with 10-stage loading and the last stage loading of 250kPa. Figure 4 is the p-s curve of static load test. A total of 2 static cone penetration holes, and try to keep in the same position. Figure 5 is the CPT-1 hole dynamic compaction reinforcement before and after the static cone penetration test results comparison chart. It can be seen from Figure 5 that the ps value of plain fill and muddy soil layer increased by 1.1 times and 2 times respectively. Based on the test results of load test and static cone penetration test, the characteristic value of foundation bearing capacity after dynamic consolidation has reached more than 120kPa, which meets the design requirements.
Compaction
Published in Bernardo Caicedo, Geotechnics of Roads: Fundamentals, 2018
Dynamic compaction increases soil density as the result of a combination of dynamic stresses and accelerations within the soil mass. Nevertheless, different types of dynamic stresses affect compaction in different ways: Compression waves increase the contact forces between particles, augmenting their frictional shear strength.Depending on the magnitude of the shear stress, shear waves can produce tangential displacements between particles that lead to particle rearrangement.Tensile stresses which follow compressive waves decrease the magnitude of contact forces between particles thereby decreasing frictional shear strength and improving the efficiency of the shear waves.
Ground Improvement
Published in Jan van ‘t Hoff, Art Nooy van der Kolff, Hydraulic Fill Manual, 2012
Jan van ‘t Hoff, Art Nooy van der Kolff
Dynamic compaction is a technique used for in-situ densification of granular soil deposits by heavy impact. This technique primarily involves dropping a heavy weight repeatedly on the ground surface at a regular grid of impact points. Compaction of the fill or subsoil is achieved by a re-arrangement of the grains as a result of the shear strains induced by the impact of the heavy drop weight. Physical displacement of particles and, to a lesser extent, low-frequency excitation will reduce the void ratio and increase the relative density. The stress waves generated by the weight contribute to the densification process. The effectiveness of the method decreases with increasing compressibility (or crushability) of the materials to be compacted.
Strength and structural variations in dredger fill subjected to vacuum dynamic consolidation
Published in Marine Georesources & Geotechnology, 2021
You Zhou, Hongtao Fu, Tian Jin, Mingfeng Li, Junfeng Ni
The dynamic compaction (DC) method, which was originally developed by Menard Inc. of France in 1969, has been applied to various soil types in diverse conditions, and especially to gravel soil, miscellaneous fill, sandy soil, and unsaturated cohesive soil, because of its satisfactory performance (Menard and Broise 1975; Poran and Rodriguez 1992). Subsequently, traditional DC methods have been modified and applied to soft clays (a process called dynamic consolidation) by installing vertical drainage elements, which commonly use a layout of prefabricated vertical drains (PVDs) (Chu, Bo, and Arulrajah 2009; Basu and Prezzi 2007; Lee et al. 2021). The combined vacuum preloading (VP) and DC method combines the advantages of both VP and DC, and introduced the concept of drainage consolidation in the dynamic reinforcement method (Chang et al. 2010; Deng and Xu 2010 ; Wei et al. 2018). The application of dynamic stress imposes instantaneous prestress on the pore water and creates instantaneous pore water pressures. VP can help accelerate the dissipation of excess pore water pressures (Cai et al. 2017, 2018; Indraratna et al. 2005; Wang et al. 2018, 2020; Zhou, Wang, et al. 2021; Zhou, Cai, et al. 2021) during DC, and rapidly drain water from the soil. Consequently, the strength of the ground soils increases significantly. Compared to other reinforcement methods, the vacuum dynamic consolidation method offers the advantages of a short construction period, low cost, and remarkable reinforcement effect; however, the DC parameters related to the number of repetitive impact loads has not been explicitly considered in previous studies.
Investigation of various gram-positive bacteria for MICP in Narmada Sand, India
Published in International Journal of Geotechnical Engineering, 2021
Meghna Sharma, Neelima Satyam, Krishna R. Reddy
Soils are heterogeneous, disperse, multiphase, and porous system (Fredlund and Rahardjo 2011). Various challenges which are faced during and after the construction of a structure are associated with soil due to its poor bearing capacity, settlement, drainage, erosion, liquefaction, etc. (Terzis and Laloui 2019). The conventional ground improvement methods involve enhancing the physical, chemical, mechanical and mineral composition of the soil. These techniques involve addition of cement, lime, chemical, and supplementary cementitious material such as fly ash, rice husk ash, and blast furnace slag for soil stabilization. Cement, lime, and chemicals can lead to air pollution by emitting carbon dioxide during the manufacturing phase or usage and permanent contamination of soil and groundwater (Benhelal et al. 2013). The use of synthetic materials in chemical grouting release toxins in the natural environment and endanger human health (DeJong et al. 2010). The other conventional methods comprise of mechanical compaction, which involves vibroflotation, dynamic compaction, blasting, construction of compaction piles, etc. These compaction techniques require heavy equipment, energy resources, and create soil disturbances in surrounding areas (Wang et al. 2017). The conventional compaction techniques suffer from some limitations such as they are adequate and economical up to a depth of 10 m and require more energy efforts for larger depths. Dynamic compaction methods are suitable for sandy soils only (Indraratna, Chu, and Rujikiatkamjorn 2015).
Laboratory fatigue performance of the cement-stabilised loess fabricated using different compaction methods
Published in Road Materials and Pavement Design, 2023
Tian Tian, Yingjun Jiang, Yong Yi, Jiangtao Fan, Changqing Deng
Loess is widely distributed throughout the world. Generally, engineering quality is affected because of its properties, including porosity, vertical joint development, strong water permeability and collapsibility (Liang et al., 2018; Xue et al., 2019; Zhang et al., 2018; Zhang et al., 2018). Therefore, in order to improve the engineering performance of the foundation, treatment measures should be taken during the development, which is Dynamic compaction and improvement, of the collapsible loess layer (Evstatiev, 1988; Yin et al., 2016). Dynamic compaction ensures the stability of subgrade soil by improving the degree of compaction (Kozubal et al., 2014; Zhang et al., 2020). The improvement method of stabilisation using additives and binders is to add other materials into the soil to improve the engineering performance index of the soil, which is a relatively common method. The existing admixtures for this purpose include cement, lime, fly ash, nanomaterials, fibres, lignin derivatives, and others. The effects of additive content, curing time, porosity and compaction degree on the physical properties, strength parameters (friction angle and cohesion), mechanical properties (mainly including compressive strength, shear strength, tensile strength, etc.) and freeze–thaw resistance of stabilised loess were studied. The application of different materials stabilised loess is different, mainly used in road, geology, construction, water conservancy, agriculture, and other fields. Among them, cement-stabilised loess (CSL) is most widely used in road engineering (Cui et al., 2019; Haeri & Valishzadeh, 2021; Jia et al., 2019; Jia et al., 2020; Julphunthong, 2016; Li et al., 2019; Liu et al., 2016; Lv et al., 2018; Sarli et al., 2020; Tabarsa et al., 2018; Wang et al., 2019; Zhang et al., 2019; Zhang et al., 2019).