Abstract This study assessed the practice of slope stabilization along highway road between Mugling and Narayanghat with reference to existing scenario-highly unstable slope in Nepal. Slope instability issues mainly along Siwalik to lesser Himalaya region have become key and common problems. Geomorphological setting in that region is quite different from south to north profile of Nepal. The geological setting and structures are major factors which controls geomorphic features in Nepal. Several kilometers of highway corridor have been running along the mountainous region. The slope instability problems along road are mainly due to cut-off of mountain and their characteristics. Such issues along highway corridor highly influence overall road connectivity the country. Of many such issues, Mugling-Narayanghat Highway Road is considered to be lifeline in Nepal, which connects all parts of country with capital city Kathmandu. More than 20,000 vehicles have been running daily through this highway to all parts of Nepal from Kathmandu and vice-versa. The slope stabilization and management practice includes application of civil engineering and bioengineering techniques according to mechanisms of slope instability. 1. Introduction Major slope instabilities are related to mass-movements that have always been major problems in Nepal. The fragile geological condition and intense rainfall and topography of area leads gully erosion, riverbank cutting, landslides, debris flow, rock fall & rock slide and human intervention in the natural environment have been the major factors triggering the mass movement activities, which lead to several slope instabilities in Nepal. Landslides and debris flow have caused great damage to lives, property and infrastructure such as roads, and bridges. The Mugling -Narayanghat section of highway road lies between latitudes of 27°45'00" to 27°52'30" and longitudes of 84°25'00" to 84°35'30" at the Central part of Nepal. This highway is well known as lifeline of Nepal. The 36 Km. long stretch of Mugling -Narayanghat highway connects East-West Highway (Mahendra Highway, India Border), Prithvi Highway (Kathmandu-Pokhara-Baglung-Jomsom-Korolla, China Border) and Araniko Highway (Kathmandu-Kodari, China Border), Kathmandu-Trishuli-Dhunche-Syaprubesi-Rasuwagadhi, China Border). It is a major part of Asian Highway and also connects capital city Kathmandu with other parts of country as well as helping develop international connectivity. This highway was constructed in assistance of Peoples Republic of China. Previously this was single lane highway. Recently, it has been extended in double lane since vehicle density and inter-road connectivity have been rigorously increased in the country for decade.

Abstract Rock masses are often heavily jointed and instability involving falling or sliding of rock block may arise upon excavation. As such, supports or reinforcements are required to stabilize the unstable rock blocks. Accurate prediction of mode of rock block failure and volume of unstable rock block are essential for the design of underground excavations in jointed rocks. Traditionally stability analysis involves a tetrahedral block formed by an excavation free face and the mean orientation of three rock joints and this is termed as the deterministic analysis. However, the orientation of rock joint may be widely scattered and Fisher distribution is commonly employed to evaluate the scatter of joint orientation. In the present study, joint orientation surveys obtained from the field are evaluated. It is found that Fisher distribution may not represent the true dispersion of the rock joint orientation for many cases. Goodness to fit test is employed to evaluate the fitting of the field data. The results show that Kent distribution is more appropriate to represent the dispersion of rock joint orientations. A probabilistic simulation is then employed to generate the distribution of volume of unstable tetrahedral rock block based on the mean orientation of the rock joint and its orientation dispersion obtained from Kent distribution. The simulation results are then compared with that determined from deterministic approach which only employs the mean rock joint orientations.

Abstract Rockfall is one of the most frequent, major hazards in mountainous areas and along engineered slopes worldwide. Accurate estimation of rockfall dynamics is essential for rockfall risk assessment, design and performance evaluation of preventive structures. Although many rockfall simulation codes have been developed, a major variable involved in rockfalls, the rock-shape, which strongly affects the rockfall events, is still poorly considered. Three dimensional discontinuous deformation analysis (3-D DDA) is an effective and helpful tool on rockfall analysis which can explicitly account for rock-shape. In this paper, a practical 3-D DDA code is demonstrated to be capable of simulating free falling, rolling, sliding, and bouncing with high accuracy, which indicates the implemented code is capable of providing reliable rockfall analysis. Rockfall simulations are performed on both idealized incline planes as well as bin-planar slopes. Particle shape index has been induced to investigate the influence of rock-shape after impacts occurred. The rockfall movement behaviors: lateral dispersion and jump height are used to obtain the influence of rock-shape. The analysis provides a more detail description of rock masses and useful information on consideration of rock-shape in rockfall simulation.

ABSTRACT Analytical solution and simplified design procedure was presented for evaluating the response of existing joint rock slope subjected to excavation. In jointed rock slope engineering, the stability of rock is controlled in a sense by the number of blocks, i.e. the size, orientation and locations of the discontinuities, especially the key blocks for a given excavation geometry. Key block failures occur where blocks of rock are separated from the rest of the rock mass by discontinuities. In this research, according to block theory, the new block stability analysis model was developed through visual C++ and computer graphics. This model assumed that rock mass consists of blocks and each block is formed by particles arranged in a specific way, thus formulating a combination of block model and particle model. This software adopted vector analysis, which can simulate all excavation planes especially in the tunnel and other underground structures. It can also create three-dimensional structural model and analyze mobility of key blocks in the simulation planes by means of geometry and kinematics theory. The distribution of all key blocks and the quantitative data were analyzed by means of the newly developed program. It can be concluded that the new code was a tool for modeling blocky rock masses. Moreover, this model was verified by an example of rock masses under uniaxial loading. It was shown that numerical results agree well with the theoretical ones and laboratory tests not only for deformation process but also for the failure process.

ABSTRACT Hydraulic Fracturing has been used successfully in the oil and gas industry to enhance oil and gas production in the past few decades. Recent years have seen the great development of tight gas, coal bed methane and shale gas. Natural fractures are believed to play an important role in the hydraulic fracturing of such formations. Whether natural fractures can benefit the fracture propagation and enhance final production needs to be studied. Various methods have been used to study the effect of natural fractures on hydraulic fracturing. Discontinuous Deformation Analysis (DDA) has been used to couple with a fluid pipe network model to simulate the pressure response during hydraulic fracturing. In this paper, the effect of natural fractures on hydraulic fracturing will be studied. In particular, the effect of several physical properties on fracture initiation and propagation will be addressed. They include rock joint properties, joint orientations and extensions. It will be shown that DDA is a promising tool to study such complex behavior of rocks.

Abstract: Constructing mountain roads in harsh terrains is a challenge to the engineering and development of southwestern Saudi Arabia. Al-Baha 32 km-mountain road is constructed at steep slope rock masses, where many rockfalls incidents were experienced. A 100 m long portion of the road, suffers from frequent rockfalls. The rock masses are mainly igneous rocks of medium to low quality. The rock slope-cut has no bench for 20 m, 70°–90° inclination, and 30 m height. Absence of ditches and support systems aggravates the daily road conditions. The RocFall computer program was utilized to perform the risk analysis on such steep man-made and natural rock. Geotechnical parameters such as block size, seeder points of blocks falls, slope angle, restitution coefficients, and slope roughness were used to identify properties of the potential and fallen rock blocks such as: bounce height, kinetic energies (total, translational, and rotational), and translational and rotational velocities. The program modeled the proposed location and energy of the rock blocks barrier's heights and locations, collectors, and proposed slope safer redesign. The results of the study provide a solution to prevent rockfalls, and could be applied at similar conditions. 1 INTRODUCTION Slope failures, landslides and rockfalls are frequently occurred on mountain roads, at rugged terrains. One of the most difficult terrains in western Saudi Arabia is Al-Baha descent, which is characterized by sharp cliffs and high elevations which reaches above 2,000 m above sea level. The highest elevation at the descent is about 2,200 m (at km 0) above sea level, where the difference in elevation from the highest to lowest elevation is about 1,750 m, the difference is about 450 m at km 32. The descent lies between longitudes 41°25"E and 41°29"E and latitudes 19°47"N and 20°01"N; see Fig. 1. Al-Baha escarpment 50km-road starts southwest of Al-Baha city, and runs through Al-Baha descent. The road connects the highlands where Al-Baha city is located with the lowlands at Al-Mukhwah town. Along this distance, natural slopes in addition to many man-made slope cuts and engineering structures are located. Al-Baha descent includes three distinct geomorphologic terrains: a dissected upper plateau of low mountains and hills, a precipitous escarpment, and a low-lying coastal plain (Fig. 2). 2 BRIEF GEOLOGIC HISTORY The geologic history indicates that the escarpment resulted from a 3000 m lowering of Tihama Coastal Plain during the Tertiary opening of the Red Sea. Al-Baha descent's road is contained almost within a structurally controlled narrow valley, called Wadi Rash. Steep tributaries start from the escarpment ridge, and radiate out from the wadi head and cut deeply into the valley sides and escarpment face. Al-Baha region is underlain predominantly by a north-south trending belt of Precambrian schistose rocks comprised predominantly of fine grained mafic to intermediate extrusives, intrusives and pyroclastics with minor intercalations from clastics and metasediments [1]. The majority of the rocks at the descent area have been subjected to greenschist and amphibolite facies metamorphism [2].

Abstract: Flow through fissures in rock mass applies simultaneously the normal hydrostatic seepage pressure and the tangent hauling pressure (the dynamic seepage pressure) on fissure walls. The cubic law of single fissure flow, the seepage theory and the basic equation of fluid mechanics are utilized to deduce the equations for the hydrostatic seepage pressure and the hauling pressure under three cases of single fissure without fillings. single fissure with fillings and water-filling flow. A computation example is also given to analyze quantitatively the double mechanical effects of flow through fracture network in rock mass. It can be shown that both the hydrostatic seepage pressure and the hauling pressure make the stress components in rock mass bigger, and especially the hauling pressure makes the shear stress component obviously much bigger. I INTRODUCTION Analysis of coupled seepage and stress fields in fractured rock mass is extensively concerned with by the researchers and engineers in the field of geotechnical engineering in the recent years (Louis, 1974: Oda, 1986: Tsang, 1987: Wu Yanqing, et al, 1995). The key for couple analysis is the interaction mechanism between stress and the fluid flow. The principle of effective stress is extensively applied in the recent research for couple analysis, in which only the hydrostatic seepage pressure is considered and the effect of hydrodynamic seepage pressure on the deformation of fractures is neglected. In fact, when the hydraulic gradient is large (such as between upstream and downstream of high dams, near pumping or pressuring wells, etc.], the hydrodynamic seepage pressure is too big to be neglected. The fluid flow through fractures exerts simultaneously the hydrostatic seepage pressure and the hydrodynamic seepage pressure on the fissure walls. The hydrostatic seepage pressure makes the fracture aperture larger, and the hydrodynamic seepage pressure (i.e. the hauling pressure) exerts the tangent pressure on the fissure walls. Wu Yanqing (1998) proposed the effect of the hauling pressure by lowering the shear strength of rock and soil mass. The purpose of this paper is to deduce the equations for determining the hauling pressure and hydrostatic seepage pressure by means of the momentum law of fluid mechanics and the cubic law of the single fissure flow. The equations are designated for the cases of no-filled fissure, filled fissure and the combined flow of fluid and the fillings, respectively, which are the foundation of the interaction mechanism between stress and fluid flow in fractured rock mass. A computation example is also given to analyze quantitatively the double mechanical effects of flow through fracture network in rock mass. 2. DOUBLE MECHANICAL EFFECTS OF FLOW THROUGHSINGLE FISSURE The basic assumptions applied in this paper are the same as those for deducing the cubic law of the single fissure flow (Bear, 1979 ). That is, a single fissure distributes in the rock mass, the aperture of which is constant, the extending length of which is infinite and the walls of which are straight, smooth and stationary.

ABSTRACT: Several studies until now have been carried out on the variance of strength when curing concrete is subjected to Vibration. But the vibration sources considered on these studies were impact, shaking table and surface blasting Mortar lining model with cylindrical shape was made for laboratory tests and real concrete wall and bottom lining model was built in tunnel for field test. The results of the laboratory test showed that vibration with 2cm/sec increased P-wave velocity of mortar lining model and vibration with 5cm/sec could decrease P-wave velocity. The results of field test showed that compressive strength of all lining concrete subjected to blast-vibration below 2.5cm/sec for curing period was increased. The critical value of blast-vibration on concrete after 5 hours of casting was 3–4cm/sec, which can decrease the strength of concrete from small-scaled test blasting on concrete lining. This result was in accordance with the result when compared with P-wave velocity. I. INSTRUCTION Mostly, the lining-concrete at tunnel site has been poured after the blasting work for the excavation of rocks in Korea. To do these two works simultaneously can reduce working hours for tunneling, but blast-vibration generated by blasting work can cause damage of curing lining-concrete. Damages of curing lining-concrete mean the strength decrease of concrete or occurrence of cracks at lining, so many studies to determine the effect of blast-vibration on curing lining-concrete in tunnel are necessary. The strength of concrete is increased gradually after casting. Therefore early aged concrete is more dangerous by blast-vibration. Lining-concrete poured in tunnel is subjected by blast vibration of which dominant frequency is over 150Hz. But the dominant frequency of vibration in several studies conducted to determine the effect of vibration on curing concrete until now was mostly below 100Hz. Also vibration source in these studies was not tunnel blasting but was shaking table, impact hammer or surface blasting (Bastian, 1970; Howes, 1979; Desai et al, 1984; Lim et al, 1994; Hulshizer, 1996). Therefore, in this study impact hammer test at laboratory and blast-vibration test at tunnel site were conducted to determine the effect of vibration of which dominant frequency is in the range of 150–300Hz on curing lining concrete. We measured the strength and elastic wave velocity of concrete specimen at 28 days after casting and the variance of strength and elastic wave were analyzed according to magnitude of vibration that subjected to lining concrete. 2. IMPACT VIBRATION TEST 2.1 Test Procedure Mortar lining model with cylindrical shape was cast between sheeting and rock block. The structure of this model is similar to that of concrete lining in tunnel site. Two types of hexahedral rock block were used. The size of 30B block is 300 x300x300mm, and that of 50B block is 300x300x500mm. A cylindrical hole to copy tunnel was built by coring at the center of each rock block. The diameter of cored hole at each rock block is about 100mm and the thickness of mortar lining model is about 12mm.