The use of construction and demolition (C&D) waste in road construction has been an important and challenging issue in recent years. In this research, geotechnical characteristics of recycled combined construction and demolition waste (RCCDW) at Fooladshahr (located in the Isfahan province, Iran) are studied to determine whether they are an appropriate candidate in road base and subbase. Laboratory tests including sieving, soundness, Los-Angeles (LA) abrasion test, compaction, and California bearing ratio (CBR) are among the tests performed on these materials. The tests were carried out on two types of samples, namely, RCCDW and natural standard aggregates for road base and subbase layers. In Iran, often, no separation is made on C&D wastes such as concrete crumbs and brick lumps. To the best of the authors' knowledge, the majority of the previous studies have been conducted on different percentages of concrete crumb and brick crumb or a combination of both. In comparison, the present study examines almost all types of construction and demolition wastes in place. The obtained results show that after initial recycling and resizing, residues have several remarkable characteristics for use in the base and subbase layers. Although their compressive properties and CBR number were less than the standard limits, they were improved by cement stabilization and became suitable for these road layers. The results show that the maximum dry density of without-cement wastes after stabilization with 12 percent cement (by weight), increased from 1.83 to 2.10 g/cm3, and their CBR value increased from 65.8% to 88.6%.
Problem statement: The dam body and foundation seepage is one of the important points in design parameters. This index is related to the permeability. There fore permeability is one of the basic parameter in design grout curtain, prevent water escape from foundation and avoid negative seepage pressure in borrow materials, so grouting is used. Grouting means injected materials like cement or chemical materials under pressure to rock or soil layers. Approach: Purpose of grouting is treatment fractures, fissures, increase strength and decrease seepage. Grout curtain is used for sealing beneath dam body and other structure to obtain above aspects. Results: The present research dealing to study the geotechnical characteristics and conditions of two damsites (Kavar and Sheshpir dam) regarding to their permeability and groutability. Permeability in rock mass is controlled by jointing and their characteristics. The Kavar dam may be constructed on Gareh Aghaj river. This site is located in 40 km southwest of Fars province, Iran. The river flow direction is parallel to the local syncline axis. The main geological features of damsite are faults, fractures and gypsum lenses that they may lead to water escape from reservoir. The rocks in the right abutment of the dam are heavily crushed with low strength. Therefore it is expected that water escape from this zone and some parts of dam axis may happen. This is approved from boreholes logs analysis and Water Pressure Tests (WPT). The other dam which called Sheshpir is located in west of Shiraz, Iran. Regarding to structural geology of this site, two large anticlines are extended in general direction of Zagros mountain range (northeast- southwest). The geology index features are karstic and jointed rock with faults. In general, regarding the grout-curtain design for each case, it is necessary to evaluate the volume of grout and injection system. Because of complexity of local structural geology especially rock foundation, it is difficult to estimate above-mentioned parameters. Conclusion/Recommendations: Therefore, through a number of WPT in both sites, the Permeability and hydro fracture tests results were used in the foundation for the design of the grouting program. using SPI rock classification systems, it is possible to identify the karstic features of the formation and the relationships between the permeability and groutability. This method that first expressed by foyo identify the special classification for grouting. In this system use results of Water Pressure Test (WPT) and Rock Quality Design (RQD) simultaneously. With the help of these two parameters rock class and grout complex is identified.
Prediction and control of the excessive settlements are very important in the design of different structures. In recent decades, many ways of prediction of settlement have been developed by researchers. Using soil models via numerical methods for prediction of soil behavior is one of the newest of them. In this regard the critical state models have been used widely for this purpose. The Modified Cam-clay model is an elastic plastic strain hardening model that is based on Critical state theory. This model is used in geotechnical engineering practice. Nevertheless, due to some reasons using of this model is in doubt for practical issues. In this paper, a pair of circular and rectangular footings has been modeled via finite-element method and Modified Cam-clay model in a case study. In the next step, the predicted and monitored settlements of these footings were compared. Finally, relatively good and conservative performance of Modified Cam-clay theory is shown in practice, as the main aim of this paper.
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