Journal of Engineering Geology

---

Stability and safety of the dam is one of the most important challenges during construction and operation. The aim of this study is to make accurate water table and piezometric heads through embankment and its foundation of the Shahghasem dam which is located near Yasouj city. Applying geostatistical, Simple Kriging, Ordinary Kriging and Weighted Moving Average, interpolation was done using Gaussian, exponential and spherical models. For comprising the results, we use the statistical index including MAE, MBE, RMSE and GSD. Results indicate that Simple Kriging with Gaussian model is the best one, while Ordinary Kriging with Gaussian model and Ordinary Kriging with spherical model are in the next order. The Weighted Moving Average method with different exponents shows a significant error comparing to other methods. As a result, the depicted maps display a cavity through foundation near right abutment of the dam. Finally, existence of probable cavity in foundation may cause piping and internal erosion

---

Geotechnical engineers, in many cases face with low strength or high swelling potential of clayey soils. Stabilization methods are used to improve the mechanical properties of this type of soils. Lime and cement are the most popular materials used in chemical stabilization of clayey soils. If sulphate exists in the stabilized clayey soil with lime, or if soil is exposed to sulphates, problems such as strength reduction and swelling increase will occur. Reuse of industrial residual such as Rice Husk Ash (RHA) can be beneficial from the economy point of view. RHA includes a proper amount of silica with high specific surface area which is very suitable for activating the reaction between the soil and lime. In this paper, chemical stabilization of gypsum clays using lime and RHA is addressed Sulphates exist in the constitution of the soil. Unconfined compression strength and swelling potentials of the stabilized soil are evaluated. The results of this study indicate that RHA has positive impacts on improving mechanical properties of the gypsum clays stabilized with lime. From the view point of strength and swelling characteristics, and economy, addition of 6–8% lime and 8-10% RHA as an optimum amount is recommended.

---

A jointed rock mass presents a more complex design problem than the other rock masses. The complexity arises from the number (greater than two) of joint sets which define the degree of discontinuity of medium.  The condition that arises in these types of rock masses is the generation of discrete rock blocks, of various geometries. They defined by the natural fracture surfaces and the excavation surface. Stability problems in blocky jointed rock are generally associated with gravity falls of blocks from the roof and sidewalls. Whereas for block defined in the crown of tunnel,the requirement is to examine the potential for displacement of each block under the influence of the surface tractions arising from the local stress field and the gravitational load, in this paper various types of wedge formation in the crown of tunnel due to intersection of joint sets with various dip were examined. The state of stability of the wedge was then assessed through the factor of safety against roof failure. Following that the formed wedges in New York city and Washington D.C tunnels crown were investigated with limiting equilibrium analytical method and by use of Hoek and Brown failure criterion. The obtained results from analytical method corresponded with field observation.
 

---