نشریه زمین شناسی مهندسی ایران
سال سوم شماره 1 (بهار و تابستان 1389)

The purpose of this study is to investigate the landslide hazard in a coastal area of Caspian Sea elongated from Nowshahr to Ramsar. High population density and lack of plains, as well as increased constructions and architectural and agricultural activities on slopes highlight the necessity of such studies in this area. Landslide distribution map for the area was achieved through field studies. According to these studies, this area has a high potential for landslide incidence, and various kinds of Mass wasting can be observed across the area.
To analyze landslide hazard in the area, we considered such factors as slope, geology, fault, river, slope aspect, elevation, land use, access routes and shear resistance as effective factors in landslide incidence. Data were digitalized using ArcGIS software and stored as information layers.
To develop the Landslide hazard zoning map for the area, method of AHP have been used. The map then are classified into five hazard ranges of very low, low, moderate, high and very high.
Evaluation of zoning map with regard to landslide density and stable points shows that obtained maps hold an acceptable validity.
Results analysis shows that slope, geology and fault are among the most important factors involved in landslide incidence.
Developed zoning map can be practical in engineering projects architectural activities in the investigated area.

Tabriz city is located in a tectonically active region and on sandy, silty sediments. Because of high level ground water in some part of the city, occurrence of liquefaction is probable during strong earthquake. Therefore assessment of mentioned phenomenon is necessary for construction of infrastructure. In this paper using standard penetration test (SPT) results, empirical relations and graphs suggested by NCEER the liquefaction potential of soils in the second line of Tabriz metro path, is assessed. At first by means of corrected SPT values, depth of groundwater and fine content of soil, the safety factor against liquefaction is calculated. Then using ArcGIS9.3 software the liquefaction potential maps of path alluviums in 8, 10, 12, 14, 16 and 18 meters is provided. Based on assessments, the safety factor against liquefaction in eastern and western part for most regions is greater than 1. But in central part of the path, there are regions that have safety factor of less than 1 and occurrence of liquefaction is probable.

One of the important problems of municipal management is the corrosion of buried concrete and steel pipe such as water and Gas pipe and Foundation of structures. The corrosion phenomena existed in all type of soils and its severity are related to properties of soil and environment. In this study, the effective parameters on soil corrosive are induced and the surface soil characteristics in Mashhad city are investigated. Based on the cumulative effects of five parameters of texture, PH, Cl-, SO4-2 and electric specific strength, the soil corrosive zonation map of Mashhad city are produced. The data bank includes more than 700 boreholes and the geoelectrical study achieved in different projects in the city. The results show that the most surface soil under Mashhad city area are classified as medium to low corrosive soil and only small part of east, north east and central part of Mashhad city have the high corrosion potential. The high corrosion hazard mainly coincide with area covered by the demolition and construction soils in bank of streams and out of city in past.

Karaj - Tehran water conveyance tunnel (LOT1) was excavated by TBM with 4.66 m diameter whereas the utilization factor is different with tunnel length. According to geological condition, excavated length and personal skill, TBM performance has been compared in four equal parts of tunnel. Evaluation of TBM Activity and delay time shows that in addition of specified factors, the utilization factor also depends on the overlap of activities. In this project utilization factor for every part is 18.30, 22.26, 16.09 and 16.08 respectively.

The algorithm of rock mass variation with depth has been proposed on the systematic viewpoint for tunneling in this research. At first, at proposed algorithm, rock mass data has been investigated at different stages of geotechnical studies in a systematic process. Then, collected rock mass data has been classified based on the index parameters of ground behavior. Finally, the ability of depth parameter has been proved for modeling the variation of rock mass characteristics by quantitative and qualitative method. Therefore, depth dependent variation of rock mass characteristics is applicable phenomenon for designing the tunnels. Classification of rock mass data based on index parameters of ground behavior produces the generalization of past results to the similar rock mass condition. Thereupon, geotechnical studies transforms to comprehensive structure having determined final goals which grows the data basics effectively. Performances of proposed algorithm has been estimated for depth dependency of 11 rock mass characteristics such as: spacing, joint persistency, joint aperture unconfined compressive strength, elastic modulus, RQD, BRMR, JCR, deformation modulus, rock mass strength and continuity factor in 12 twin tunnels of Khorrammabad – Pol-e- Zal. According to the results, increase of depth from 50 to more than 250 m has been coincident with improvement of rock mass characteristics and joint properties and equivalent continuous rock shifts to range of intact to blocky rock. Therefore, variability of rock mass characteristics with depth has to be considered for designing the support system, excavation method and tunneling contracts.

Due to the arching behavior of concrete arch dams, the hydrostatic loads imposed on dam body are transferred to the abutments. Accordingly, an accurate evaluation of the stability of abutments is very important. The failure mechanism of abutment is substantially governed by a network of discontinuities crossing the abutment. Meanwhile, the flowing water through discontinuities provides an easier condition for discontinuities to slide and/or open. In this paper, the effects of fluid flow and mechanical characteristics of joints are treated on safety of abutments. Though, a full 3D simulation of dam body and its surrounding rock mass is needed for a complete understanding of the problem, but in general, the 3D jointed abutment stability analysis considering hydromechanical interaction are too time consuming and complicated. Therefore, in this study, a 2-D DEM model for the most critical region of a typical arch dam abutment resulted through a 3D FE modeling is considered to evaluate the abutment safety. In this research, the effects of fluid flow and mechanical characteristics of joints on the safety are investigated through SRF and increasing water pressure methods in both dry and saturate assumptions. In order to recognize the conditions leading to failure in abutments, the values of maximum sliding, maximum opening, opening and sliding intensity and maximum resulting water flow rate along discontinuities are used as failure criterions. The results demonstrate that the assumption of dry abutment is not proper for evaluating the stability condition and may submit the safety factors much larger than the real values. Moreover, the strength characteristics of rock joints are less significant on the stability of abutment.

Critical filter is one of the principal parts in an embankment dam which is preventing the dam against erosion. There are important technical and economical problems for engineers to select the filter characteristics which are acceptable from view points of necessity and economical aspects.
Since, experimental methods may cover different parameters of the soil-filter system; experimental modeling is characterized as the most appropriate method to investigate soil-filter system. No Erosion Filter (NEF) test has a high capability to evaluate the soil-filter system. Most design criteria and many researches for grading curve of filter only pay attention to the size of D15 of filter and there are fewer attentions to smaller size and fine content of filter. In this research using two groups of filters which have same grading curve in larger size of D15 but are different in smaller size, 24 NEF tests were performed. Contrary to existing criteria, the obtained results revealed considerable effects of fine content and the particles which are smaller than D15 and these factors can cause improvement or weakening filter performance to control soil erosion.