نشریه زمین شناسی مهندسی ایران
سال یکم شماره 4 (پاییز و زمستان 1387)

Although occur of natural events such as landslides can not be prevented, but their losses and impact can be reduced by recognition, assessment and risk management. Landslide specific risk may be defined as degree of vulnerability from a landslide event in every point of region.
In this research the elements at risk are population; constructions, natural and agricultural resources, that potentially affected by the landslide hazard.
Landslide frequency and relative preference of effective factors index have been used in hazard assessment. Vulnerability mapping carried out with use of run out distance index and frequency of exposed elements.
Index overly multi class model is used to creating the weight maps. This is an increasing operator and the high weight in its pixels shows high sensitivity. Therefore it is suitable for sensitive land use. The final specific risk map is necessary source on land use planning and prediction of losses in change land use or load frequency of land.

Quick estimation of possible problems is very important for tunnel excavation through anisotropic and low strength rock masses like shale and schist. This paper deals with the squeezing problem in the second segment of Azad tunnel in KordestanProvince which passes through phyllite and slate weak rock masses with squeezing potential. For this purpose four experimental methods were used. According to the obtained results, squeezing value and strain of tunnel wall in the critical section with maximum overburden (760 m) was determined and then support pressure has been calculated by using Hoek & Marinos equation. At final, the results of above experimental methods has been used for estimating of starting squeezing depth nomination in this segment of tunnel, and this depth has been estimated 180 m.

Further to environmental criterion, one of the most important issues in land slide stabilization is the economical feasibility of the project. Conventional methods are mostly costy and thus may not be used in land slides situated in rangelands, agricultural or forest areas in which the value of land is very low. In this paper the application of SLS (saturated lime solution), recently developed for soil shear strength improvement, in land slide stabilization projects is examined. The different steps, including subsurface exploration, laboratory tests, numerical modellimg and conclusion are explained. Then the results of the above mentioned steps for a real case are presented and disxussed.
In this technich, after studying the stratification of site, the mechanical properties of soil including chesion, in ternal friction angle, density, and hydraulic conductivity, the relationship between SLS volume and improving of c and of soil is stablished by means of laboratory tests. Using reliable softwares, numerical hydraulic and mechanical models of the site is prepared to determine the required volume of SLS to be penetrated into the soil. Also the number and location of wells and/or trenches through wich SLS will have access to he soil is designed.
The results reveal that SLS technich is a low cost and environmental friendly method which can be used for civil works in the field of land slide stabilization.

In this paper the effect of creep is discussed. The burger body which is able to model the primary and secondary creep regions of rocks is applied. In order to analyze the behavior of circular tunnels in visco-elastic media and hydrostatical state of stresses, new relations are derived. The new proposed equations are able to predict the variations of the stresses and displacements during the time. In order to verify the analytical solution, a tunnel is analyzed numerically by using FLAC code. The results of these two analyses showed a proper agreement with the numerical analysis and an instrumented tunnel.

Defining indicator is used for classification of data, based on a threshold and converting qualitative to quantitative data. One of the applications of the indicatoring in estimation is indicator kriging. In the present study, two geotechnical parameters (Lugeon and RQD) from 27 boreholes, along with various structures of the Semilan dam were studied. Based on indicator functions, Lugeon parameter divided to four, RQD to three and various structures of the dam site to four indexes. Then, indicator variogram of each parameter was calculated and their variogram characteristics were extracted. The geotechnical parameters were estimated, by 3D kriging. Based on the average of kriging error (Lugeon and RQD) were also divided into four indexes. The function to locate additional drillings is based on maximizing parameters such as Lugeon, average of error estimation and index of dam structures; and minimizing RQD. The function to locate additional drillings is found by dividing the result of multiplying Lugeon, estimation error, and index of dam structures, by RQD. In this paper, based on the function of additional drilling locations, two extra boreholes were suggested for the studied dam site. It should be noted that new boreholes in early stage of drillings can more effectively reduces error estimation, compare to those drilled in the later stages. Hence, although adding two boreholes to 27 existing boreholes of Semilan dam cannot considerably decrease the error estimation, but effectively decrease the uncertainty around them.

Nowadays, the slope stability analyses are performed by limit equilibrium methods. It is necessary to analyses slope stability by probabilistic modeling due to soil and rock properties variations in different parts of structure. In this paper, the reliability analysis and probability of failure Esphordi Phosphate mine tailing dam were gained by probabilistic modeling using Monte Carlo Simulation method. The reliability analysis and probability of failure values showed that tailing dam is stable.

Seismic hazard reduction requires precise response of the building based on PGA and site effects. Characteristics of site play an important role in building devastation. Based on the code of practice for seismic resistant design of buildings, exerted lateral load on a structure depends on the soil profile of the site. The classification mainly depends on the geological and geotechnical conditions which are determined by in situ and laboratory tests. In this regards, geoseismic studies based on average shear wave velocity from surface up to depth of 30m is necessary. Thickness, velocity and sequence of the layers, specifically a surface layer with low shear wave velocity underlain by stiffer material with high shear wave velocity have remarkable effects on design spectra. While a low velocity layer considered on a high velocity one, the soil profile postulated as soil type E according to the Eurocode. In this paper, soil type E defined by Eurocode and its effects on design spectra is examined. Further more consistency of design spectra resulted from case study (seismic microzonation of Bam city) with spectra based on soil type defined by Eurocode and Standard No. 2800 are evaluated. The results indicate, if terms and condition of class E is ignored. The site may be classified as type I (Standard No. 2800) or B (Eurocode). Obtained design spectra from case study match well with spectra from Eurocode for type E. Hence, it is inevitable to allocate a group of soil type within which a soft alluvium layer overlain hard layer.