نوع مقاله : مقاله پژوهشی
1 گروه زمین شناسی، دانشگاه پیام نور
2 گروه زمین شناسی، دانشگاه پیام نور، ایران
عنوان مقاله [English]
Conducting geomechanical studies and examining the strength and type of soil before the construction of civil structures is one of the most important stages of studies in selecting the appropriate location for each geomechanical project. Geomechanical characteristics of soil are performed through surface and in-depth observations through borehole drilling, laboratory and on-site tests, and processing and interpretation of test results. In this research, the north of Choghakhor Lake has been studied in order to evaluate the potential of the region for the construction of a tourist village. In order to determine the type and thickness of soil and rock layers and to perform laboratory and on-site experiments, three boreholes were drilled. The test results show that the study site is located on young alluvial sediments of the mountainside, which is mainly a mixture of clay and silt with sand and some gravel. The depth of hand soil in the area varies from 0.5 to 1.5 meters and the level of the water table is located at a depth of more than 30 meters. Most of the standard penetration test values are observed at a depth of 6-8 m, which is due to the genesis and type of soil at a depth. According to Bell's proposed classification, more than 50% of the area's soil is in the hard category. According to the average values of adhesion and internal friction angle for drilled boreholes, the bearing capacity of strip foundation with a width of 1 to 4 meters, for three effective overhangs 1, 2 and 3 meters and length to width ratio of 1: 1 to 10: 1 it placed. The highest bearing capacity is P 2850 and the lowest is 1100 kPa. Changes in bed reaction coefficient, with changes in foundation width from 1 to 5 meters, are in the range of 34 to 286 kg / m3 and with an average value of 100 kg / m3. The range of acceptable changes in the bearing capacity of Pi, the location of most of the soil in the region in the resistant category, low water table, flatness of the study area and the consequent lack of landslide potential, indicate the high potential north of Choghakhor Lake to build a tourist village.
Today, the progress of science in the construction of building structures is such that for the construction of residential areas, basic studies are carried out to identify the geological features of the area, because the study of soil bearing capacity for the construction of buildings is of particular importance. This is done with the help of environmental surveys and perceptions and their processing. Investigating factors such as the condition of soil, rock and groundwater layers, load-bearing capacity, subsidence of foundations and seismic potential of the area are among the issues that are important and necessary to decide on the selection of a suitable location for the construction of residential structures. To achieve this, studies have been carried out in the north of Choghakhor Lake, where a tourist village is to be built, in order to measure the potential of the region for the construction of structures.
The study area is geologically located in 1: 100000 Ardal sheet and in Choghakhor block. This area is located in the construction site of Choghakhor village located in Chaharmahal and Bakhtiari province, on the north shore of Choghakhor lake and 3 km southeast of Zordegan village. After conducting detailed studies on geological features and reviewing the study background, suitable areas for study, selection and field visit were performed. Following field visits, detailed outcrops in the sections were studied, followed by raw data collection using sampling methods (e.g. Tucker, 2003). Sampling in this study was performed systematically and by measuring the slope, length and thickness of the layers by compass and meter, complete information about their geological features and geographical location was collected. In order to determine the type and thickness of soil and rock layers as well as sampling for laboratory experiments; Three boreholes with a depth of 30 meters were predicted at the drilling site. During drilling operations from different layers of tampered and intact specimens to perform the necessary tests (such as standard penetration test, granulation test, etherberg boundary determination test, determination of natural soil specific gravity, determination of natural soil moisture, direct soil cutting test, Soil consolidation test, soil sulfate and chlorine test) were prepared.
The study site is located on young alluvial sediments. These sediments are mainly fine-grained and have low to medium permeability. The thickness of hand soil varies in the range of 0.5 to 1.5 meters, the water table is located at a depth of more than 30 meters and the saturation percentage of soils in the region is on average 61%. Most of the bedrock of the study area is limestone, marl limestone and aerated limestone marl. According to the results of standard penetration test, the maximum values of standard penetration are observed at a depth of 6-8 meters in all three boreholes, which can be due to soil genesis at the desired depth. At depths of 18 m and 28 m, the standard penetration values for all three boreholes have also increased. It is noteworthy that the sequence of standard infiltration peaks with a range of 10 meters indicates changes in the genesis of sedimentation in time ranges equivalent to 10 meters of sedimentation, which can be due to climate change in the mentioned time periods. According to the Bell classification, more than 50% of the area's soil is in the hardy category and 30% in the very hard category. The soil of the pH zone has limited density changes and its average value is 1.96 kg / m3. Changes in chlorine and phosphate values are independent of depth and are 0.053 and 0.134% on average, respectively. The average soil adhesion is 14 kPa and the average value of internal friction angle is 28 degrees and the average compaction coefficient is 0.235. The bearing capacity of the foundation is evaluated according to the average values of adhesion and internal friction angle for effective slags of 1 to 3 meters, changes in the width of the foundation from 1 to 4 meters, and the ratio of length to width of the foundation from 1 to 10 meters. Took. The minimum load capacity was 1100 and the maximum load capacity was 2850 kPa. The reaction coefficient of the bed is in the range of 34 to 286 with an average value of 100 kg / cm3 due to changes in the width of the foundation from 1 to 5 meters. Amplitude of acceptable changes in the bearing capacity of the foundation, placement of most of the soil in the area in the resistant category, low water level, flatness of the study area and consequent lack of landslide potential, ease of access to the area and availability of water and energy resources, north of the lake Choghakhor has become a potential area for the construction of a tourist village.