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This paper presents a formula to estimate the stable weight of a rubble mound for breakwaters, considering the tsunami-induced overflow and seepage flow, based on the theoretical force balance among the frictional resistance of the rubble mound, the tractive force of the water flow over the caisson to the rubble mound and the seepage force of the rubble mound through the breakwaters. A series of hydraulic model tests was conducted on the scale of 1/100 for the Kamaishi Harbor Mouth Breakwaters in order to confirm the effectiveness of the proposed formula. Using the test results, the stability of rubble mounds for breakwaters was evaluated from the geotechnical engineering and hydrodynamical points of view.

Using an assumed vertical retaining wall with a drainage system along the soil–structure interface, this paper analyses the effect of anisotropic seepage flow on the development of passive earth pressure. Extremely unfavourable seepage flow inside the backfill, perhaps due to heavy rainfall, will dramatically increase active earth pressure while reducing passive earth pressure, thus increasing the probability of instability of the retaining structure. A trial and error analysis based on limit equilibrium is applied to identify the optimum failure surface. The flow field is computed using Fourier series expansion, and the effective reaction force along the curved failure surface is obtained by solving a modified Kötter equation considering the effect of seepage flow. This approach correlates well with other existing results. For small values of both the internal friction angle and interface friction angle, the failure surface can be appropriately simplified with a planar approximation. A parametric study indicates that the degree of anisotropic seepage flow affects the resulting passive earth pressure. In addition, incremental increases in the effective friction angle and interface friction angle both lead to an increase in passive earth pressure.

In recent years, with the development of China’s coastal waters and coastal urban space expansion needs, the construction of artificial islands on the sea has achieved rapid development. In order to allow it to further promote the development of Marine economy in our country, relieve the contradictions of land and environmental pressure and maintain the Marine ownership plays an important role in our country, research from the review summarizes the development of China offshore artificial island and the technical characteristics of typical artificial island has been built and under construction engineering examples, the paper introduces the construction and offshore artificial island development present situation, and sums up the construction of artificial islands facing the core issues. At the same time, based on the analysis on the status at present domestic offshore artificial island, points out the key technology of the construction of the island, and in the sea flower island project carried out by the series water power project as an example, a detailed discussion on wave flow elements, the seabed sediment, as well as the influence on surrounding channel water exchange, and the three dimensional seepage flow, etc. The research achievements of the project. The research points out that the future construction of artificial islands should return to rationality and science and pay more attention to the integration of natural ecology and environment.

Base on the design of seepage control, the three-dimensional non-steady saturated - unsaturated seepage finite element analysis program CNPM3D is used to establish the three-dimentional finite element seepage model of junction area during operating period. The seepage field of dam site area is studied under the different anti-seepage curtain arrangement scheme. Specifically, the seepage gradient and the seepage discharge of the panel, major material zone, foundation curtains and two sides abutment curtains are analyzed to evaluate the stability of the major district of dam area, in order to provide suggestions for choosing the seepage control standard in the next deepen design stage.The calculation results show that the panel and the impervious curtain anti-seepage effect is remarkable.Impervious curtain can greatly reduce the total seepage flow of the dam and its foundation.However the curtain deepened to 1Lu has little effect on seepage discharge. It is showed that the seepage prevention standards of 3 lu should be proposed in the deepen design stage for both security and economic benefit. The achievement and experience of this seepage prevention design should be taken into consideration for other similar projects.

Significant changes in spontaneous potential and exciting currents are observed during water and grout injection in a simulated porous media. Obvious correlations between the seepage flow field and the electric field in the porous media are identified. In this work, a detailed experimental study of geoelectric field variation occurring in water migration was reported by analyzing water and grout injection processes in a simulated porous media. The spontaneous potential varies linearly with the thickness of unsaturated porous media. Very interestingly, the spontaneous potential generated in the second grout injection exhibits some “memory” of previous grouting paths. The decreases in spontaneous potential observed during grout injection is very probably due to that the spontaneous potential variations are primarily caused by electro-filtration potential, as indicated by the far larger viscosity of grout compared to that of water. The geoelectric response can be utilized to effectively identify the grouting paths in water-bearing rocks.

Development of the area is characterized by a natural Yusupov slowdown selection of oil by a significant depletion of reserves and a sharp watering wells partially associated with aging wells, so to ensure the stability of oil production requires the use of technology to block the formation of washed areas to reduce water production and enhanced oil recovery, due to redistribution of filtration flows, as well as technology allows to eliminate casing flows. Currently, there is a huge amount of reagents and technologies for the technology of blocking washed formation zones (BWFZ). These technologies allow to increase the resistance in the high permeability zones layered formation that promotes redistribution of seepage flow directions in the area of low-permeability oil-saturated areas. The main objective in the development of technologies to block the formation of zones of washed and technologies associated with insulation casing flows, include the search and selection of effective compounds insulating compositions. An analysis of the fishing experience of similar works can formulate the basic requirements for blocking composition. The main objective in the development blocking out technologies in highly watered zones and technologies associated with insulation casing flows, include the search and selection of effective compounds insulating compositions. One of the promising technologies blocking formation zones are washed with injection technology gelling compositions based on aluminosilicate "Syenite". Analysis of the pilot testing of the gel-forming composition "Syenite" showed high technological efficiency, but in the analysis were identified disadvantages associated with low technological gelling composition "Syenite" associated with the preparation of these compositions, therefore, proposed a new formulation based on dicalcium silicate (2KS ) for the conditions Yusupov area Arlanskoye field having higher processability as compared to the analyze gelling composition "Syenite" for the new gelling composition based 2KS hydrochloric acid and subsequently composition "CAS", a complex of laboratory experiments. The results of studies of physical and chemical properties of a new gel forming composition «CAS». Established rheological characteristics of the new composition. The possibility and ways of regulating the composition of the gelation time. With filtration tests show that the proposed composition is capable of effectively blocking the highly watered layers.

Stability of sheet-pile walls is often very sensitive to seepage flow. In the presence of seepage flow, the reduction in passive pressure on one side and increase in active pressure on the other side of the wall increase the risk of the instability that may precede instabilities due to piping or ground heaving. In this research the earth pressure behind sheet-pile walls in granular soils is studied. The flow field is computed by the finite-element method and the slip lines (stress characteristics) method is utilised to compute the associated stress field required to compute the effective passive pressure. The same finite-element mesh and interpolation functions are used to solve the flow field and to interpolate the seepage forces in the stress field solved by the stress characteristics method. Comparisons are made to verify the numerical results with those values available in the literature; these show reasonable agreement. The stability of sheet-pile walls is then analysed for a number of different problems with varying geometries and boundary conditions. These different geometries and boundary conditions are expressed in terms of non-dimensional factors and results are plotted.

The bottom friction beneath random waves is predicted taking into account the effect of seepage flow. This is achieved by using wave friction factors for rough turbulent, smooth turbulent and laminar flow valid for regular waves together with a modified Shields parameter which includes the effect of seepage flow. Examples using data typical to field conditions are included to illustrate the approach. The analytical results can be used to make assessment of seepage effects on the bottom friction based on available wave statistics. Generally, it is recommended that a stochastic approach should be used rather than using the rms values in an otherwise deterministic approach. This is a submitted manuscript of an article published by Elsevier Ltd in Applied Ocean Research, 23 July 2014.

The present paper investigates the problem of the stability of the tunnel face under seepage flow conditions based upon the so-called “method of slices”. This computational model improves the limit equilibrium method of Anagnostou and Kovari (1996) by treating the equilibrium in the wedge consistently with the overlying prism, i.e. without an a priori assumption concerning the distribution of the vertical stresses. Furthermore, it shows that tensile failure of the wedge may be more critical than shear failure, if the gradient of the hydraulic head in the ground ahead of the face is high. For an approximate distribution of the hydraulic head in the ground around the tunnel face, we derive a closed-form solution for the necessary face support pressure. In addition, we provide normalized diagrams, which allow for a quick assessment of the stability of the tunnel face.

Z_SOIL, commercial software based on finite element technique is proposed to simulate the unsteady seepage flow through earth dams, with variable upstream water heads. Experimental work, using Permeability and seepage model is conducted to verify the reliability and the accuracy of the numerical model. The accuracy and reliability of the model are adequate to handle unsteady flow problems with complex conditions. It is also demonstrated that the method of determining the seepage surface through the saturation described is natural, logical and practical in actual applications. The method provides a relatively simple computing scheme, as compared with traditional methods

A finite element model of tailings dam model was used to simulate the steady seepage field and analysis the stability under different working conditions. The head contour, velocity, seepage flow and seepage gradient was analyzed. The stability against sliding in this tailings dam was analyzed with the help of the simplified Bishop method which is based on rigid body limit equilibrium coupled with seepage force. The security coefficient under different working conditions was calculated. The analysis result shows that the safety factor meets the specification requirements, and which provides reference for the stability evaluation of tailings dam.

The study on seepage flow passing through single fractures is essential and critical for understanding of the law of seepage flow passing through fracture networks and the coupling mechanisms of seepage field and stress field in rock masses. By using the fractal interpolation to reconstruct a natural coarse fracture, as well as taking into account the microstructure of the fracture, the numerical simulation of seepage flow passing through the coarse fractures with two distinct vertical scaling factors is conducted based on the MRT-LBM model of the lattice Boltzmann method. Then, after obtaining the length of the preferential flow pathway, the permeability of the two kinds of fractures is estimated respectively. In view of difficulties in locating the preferential flow pathway of natural fracture networks, by numerical tests a transect permeability weighted algorithm for estimating the fracture network permeability is proposed. The algorithm is not specific to one or more particular preferential flow pathways, but considers the contribution of each section to hinder the fluid passing through the medium. In order to apply the new algorithm, by capturing the structure of fracture networks based on the image-processing technique, the numerical simulations of seepage flow passing through two groups of natural fracture networks is carried out, the permeability is forecasted and the partial flows are reproduced for both cases. It is found that the preferential flow pathway emerges at the beginning of evolution, then is strengthened subsequently, and finally reaches a steady status. Furthermore, by using the proposed method some details on local flow can be clearly observed such as backflows and vortices at local branches can exist simultaneously and so forth, suggesting the validness of the proposed method for multiscale simulations of seepage flow.

U ovom se radu razmatra procjeđivanje zemljane brane simuliranjem procjednog toka i toplinskih parametara. Jednadžbe za izjednačavanje masa i za konvekciju-difuziju diskretizirane su pomoću metode konačnih elemenata radi rješavanja tih pojava u zasićenim i nezasićenim zonama. Predloženi model je provjeren na primjeru zemljane brane Shamil. Analizirani su materijali raznih karakteristika provodljivosti te je izvršena usporedba s mjernim podacima. Rezultati pokazuju da se ispitivanjem temperaturnih varijacija pojava procjeđivanja može jasnije sagledati nego kod piezometarske kontrole procjeđivanja., The earth-fill dam leakage is studied in this paper by applying the seepage flow and thermal simulation. The mass balance and convection-diffusion equations are discretized based on the finite element method to solve the phenomena in saturated and unsaturated zones. The Shamil embankment dam is used for verification of the proposed model. Different conductivity cases are analyzed and compared against measured data. Results show that investigation of temperature variations can magnify the effect of leakage more clearly than the inspection of seepage piezometric levels.

Permeability coefficient is the determining factor for physical quantities in the seepage field, which can affect the distribution of all physical quantities including seepage flow. It took a hydropower station tail race as an object, founded FEM numerical model, analyzed the influence of permeability coefficients of cut-off wall and bedrock in non-uniform seepage and got the key factors affecting seepage flow. It provides the references in theory for design and construction of the tailrace.

In order to solve the problem of differential settlement, seepage flow and stability between the new and old dam boundary in capacity increasing of the plain reservoirs, the comparative analysis on the stability of the dam slope with different methods on dealing with the new and old dam boundary was performed by numerical simulation with FLAC3D. The result shows that combining the new and old dam by using geogrid indicates superiority for reducing differential settlement, improving the dam stability and safety, etc. In the meantime, on the basis of actual site investigation and theoretical analysis, combined with the requirements of design, construction and management in capacity increasing of the plain reservoirs, the key construction technology was put forward and widely applied foreground, which can improve the quality of the construction, reduce engineering disease and provide references for capacity increasing engineering of in plain reservoirs.

Expanded polystyrene (EPS) geofoam (geofoam block) is commonly used as a lightweight fill for many civil engineering applications. However, when used for slope remediation, the behavior of geofoam block for slope systems undergoing seepage flow is not well known. In this study, a total of 36 laboratory lysimeter experiments (dimensions of 60 cm height, 20 cm width, and 200 cm length) were conducted to investigate the behavior of sandy slopes containing geofoam blocks as a lightweight fill material. These experiments were conducted with three different values of constant water pressure in the water reservoir located at one end of the lysimeter. In addition, three different configurations of geofoam block were tested with geofoam blocks placed on the face of the packed sandy slope. The dimensions of the geofoam blocks were 2.5 cm high, 5 cm wide, and 15 cm long to achieve a 1:20 scale corresponding to actual block size that is commonly manufactured. Laboratory physical test results were quantified by coupled seepage flow and slope stability models showing the adverse effect of seepage on the factor of safety (FS). Geofoam block configurations were found to be stable against seepage conditions which would cause a shallow-seated failure of the slope in the absence of the geofoam blocks. This is due to the fact that the geofoam blocks could completely fill the mass of the existing slope material subjected to failure. However, the geofoam block configurations were unstable against seepage conditions that resulted in deep-seated failures of marginally stable, sand slopes.

We propose a computational method for assessing bolt reinforcement of the tunnel face in cohesive frictional soils and weak rocks under seepage flow conditions. The method is based on limit equilibrium factors and can be applied to reinforcement layouts that are arbitrary in terms of the spacing, length, longitudinal overlapping and installation sequence of the bolts. An investigation is made into the influence of water table height on the stability of a reinforced face. In particular, we show that, if the gradient of the hydraulic head is high, then tensile failure of the ground ahead of the face may be more critical than shear failure. For an approximate hydraulic head distribution in the ground around the tunnel face and assuming uniform face reinforcement, we derive a closed-form solution for the necessary bolting density., Procedia Engineering, 191, ISRM European Rock Mechanics Symposium EUROCK 2017

In order to fully mechanized caving face bypass collapse column on safety and high efficiency, this paper do similarity simulation experiment, and obtained experimental result that main type of seepage flow includes finger seepage and surface seepage, the grout enter into around pore and occupy it’s space in grouting pressure. Moisture content of mud and sand medium is lower, grouting process can be regarded as single-phase permeability, analysis on the relation between grouting diffusion radius and other parameters. may know that grouting diffusion radius is increased with the increase of permeability coefficient and grouting pressure and grouting time, and is decreased with the increase of Porosity and grout viscosity.

Die Berechnung variabel gesattigter Stromungen durch Dammbauwerke ist von groser technischer Bedeutung. Es existieren zahlreiche numerische Ansatze zur Losung der stark nicht-linearen Richard-Gleichung basierend auf Finite-Differenzen- (FDM) oder Finite-Elementen-Methoden (FEM). Vor kurzem wurde ein neuer Modellierungsansatz vorgestellt und validiert, welcher auf der Lattice-Boltzmann-Methode (LBM) basiert. Die LBM besitzt dabei einige vorteilhafte Eigenschaften, welche die Methode zu einer attraktiven Alternative insbesondere in Hinblick auf komplexe Geometrien und gekoppelte Simulationen machen konnen. In dieser Arbeit wird die LBM auf die 2-D- und 3-D-Richard-Gleichung auf strukturierten Gittern angewandt. Verschiedene Schreibweisen der Gleichung, basierend auf der effektiven Sattigung und der Porendruckhohe, unter Einbeziehung zweier Retentionsmodelle nach Brooks-Corey und Van Genuchten werden angewandt. Die Anwendbarkeit des Verfahrens wird in Hinblick auf idealisierte Testfalle und kleinskalige sowie grosskalige Dammbauwerke untersucht. Die Ergebnisse werden aufgezeigt und mit anderen ausgewahlten analytischen, experimentellen und numerischen Resultaten verglichen. An accurate determination of variably saturated seepage flow through earth embankments is an important engineering task. Numerous approaches exist solving the highly non-linear Richard's equation for this task, typically based on Finite Element or Finite Difference formulations. Recently, a modeling approach using the Lattice Boltzmann method (LBM) for the Richards equation was presented and validated on simple test cases. Models based on the LBM have advantageous characteristics concerning simplicity, complex geometries, parallel efficiency and the possibility to easily extend the model framework to other flow processes, making it suitable for coupled simulations. In this work the LBM is applied for the Richard's equation in 2D and 3D on structured meshes. Different formulations of the Richard's equation based on the moisture content and the pore pressure are used. Two types of retention models after Brooks-Corey and Van Genuchten are implemented. The applicability of the approach is investigated using idealized test cases and scenarios concerning small-scale and large-scale embankments. The results are compared to selected analytical, experimental and numerical results.

A high seepage-flow velocity represents a potential problem for artificial ground freezing (AGF), as it may hinder the growth of an ice body and the development of a closed ice wall. To avoid such difficulties, careful thermal hydraulic analysis is necessary. This presupposes, of course, that the reliability of the underlying computational models has been verified by means of comparisons with the results of appropriate field tests or physical models. As there are scarcely any results of such tests available in the literature, a new large-scale physical model for AGF under conditions of high seepage-flow velocities has been developed. The present paper documents in detail the experimental set-up, the thermodynamic properties of the soil material, the boundary conditions, and the results of six experiments. These data are valuable as a reliable basis for the evaluation of numerical or analytical prediction models. Additionally, the paper discusses existing closed-form solutions for AGF with and without seepage flow in the light of the experimental results, from the perspective of the refrigeration time and the cooling power required for the merger of a freeze-pipe row.

Through project examples, this paper set up a two-dimensional finite element seepage flow model with the help of the Auto-BANK software, to solve the soakage line overflow points, seepage quantity and seepage gradient of the earth dam based on the basic equation of steady seepage flow of earth dam and definite conditions. It is found that this method can effectively calculate and analyse multi-media seepage flow field with complex boundaries.

Drilling bored piles foundation has been built in the dam and reservoir because of the highway bridge across the dam. Considering the bridge built, the horizontal and vertical force will be passed and act on the dam base. Based on Bishop method, the stability of the dam was analyzed and results showed that the dam can not satisfied with the slope stability requirements. Therefore, concrete measures for reinforced were put forward in order to remove dangers and reinforce the dam.

Urban development often requires the construction of deep excavations. These might be for deep basements, cut-and-cover tunnels, underground parking or underground transportation systems. The design of deep excavations is often dominated by the water flow around sheet piles or propped walls. The seepage flow influences the stability of the walls where bulk heave, piping or failure by reduction of the earth pressure may occur. Several methods of calculating the stability against seepage failure of the soil have been proposed in the literature, leading sometimes to great differences on the hydraulic head loss inducing failure. In this paper, the FLAC -2D Code using an explicit finite difference method is used to analyse seepage failure of the sandy soil within a cofferdam subjected to an upward seepage flow. Based on this study, the conditions for seepage failure occuring by boiling or heaving of the soil behind sheet piles are clearly identified.

Characteristic features are presented for the construction of deeply embedded sections of structures, for example, the erection of pit enclosures. Problems with the building of sheet-pile walls using cast-in-place piles screwed into predrilled hole under conditions whereby the natural seepage flow is retained are examined. New procedures are discussed for the installation of distributive and bracing bands for sheet piling. Conclusions concerning the expediency of use of the technical solutions under consideration, which are based on construction experience, are drawn.

Based on comprehensive literature collection, the seepage flow mechanism and the physicochemical phenomena involved are studied on the steam-foam drive in superviscous oil reservoirs. A mathematical model for steam-foam drive has been developed, including influencing factors such as surfactant concentration, noncondensing gas content, reservoir heterogeneity, etc. Taking into account specialties such as deep-burial depth and thick-pay zone of Gao-3456 well group in Gao II & III block of Gaosheng Oilfield, studies on the steam-foam drive are carried out using the developed numerical simulator. Corresponding influencing factors and feasibility are studied, the enhanced oil recovery mechanism is also discussed for the steam-foam drive in thick-layer superviscous oil reservoirs, and some instructive results are obtained.

捨石堰を越流・浸透する流れの流量を算定するために水理実験と理論解析を行った. 流れを粗面開水路流と乱流多孔体流れからなる二層流と仮定し, 上下層間の運動量交換を考慮して二層界面での内部抵抗を評価した. 捨石堰内の運動量保存は被圧多孔体乱流として定式化された. 様々な捨石粒径, 間隙率, 堰の高さ・長さ, 水深の条件下で水理実験を実施し, 水面形, 捨石堰内外の流速, 捨石の抵抗力など水理諸量の特性について実験と理論との良好な一致を得た. さらに関連パラメータの関数として流量の理論解が得られ, 実験結果との比較・検証がなされた. 本研究成果は, 堰による流量・水深制御, さらに堰の破壊条件評価など実用的な構造物設計に応用することができる.

In this study, a centrifuge model tests and effective stress analyses are performed on a breakwater subject to Tsunami such as those seriously damaged during 2011 East Japan Earthquake (Magnitude 9.0). The centrifuge model tests at a scale of 1/200 are performed to simulate the failure of a breakwater subject to Tsunami. With the effective stress analyses, this study demonstrates the importance of the mechanism of failure in the rubble mound due to seepage flow of pore water in addition to the force of Tsunami action.

Fractured seepage is an important factor affecting the interface stability of rock mass. It is closely related to fracture properties and hydraulic conditions. In this study, the law of seepage in a single fracture surface based on modified cubic law is described, and the three-dimensional discrete element method is used to simulate the dam foundation structure of the Capulin San Pablo (Costa Rica) hydropower station. The effect of construction joints and developed structure on dam stability is studied, and its permeability law and sliding stability are also evaluated. It is found that the hydraulic-mechanical coupling with strength reduction method in DEM is more appropriate to use to study the seepage-related problems of fractured rock mass, which considers practical conditions, such as the roughness of and the width of fracture. The strength reduction method provides a more accurate safety factor of dam when considering the deformation coordination with bedrocks. It is an important method with which to study the stability of seepage conditions in complex structures. The discrete method also provided an effective and reasonable way of determining seepage control measures.

Natural Science Foundation of China [51409029, 51479014]; China Postdoctoral Science Foundation [2014M562288]; Chongqing Science & Technology Commission of China [cstc2013jcyjA30006]; Chongqing Education Commission of China [KJ130412]

1. It is necessary to revise urgently SNiP 2.06.05-84x with respect to the designs of dams being constructed in the northern construction-climatic zone, i.e., to remove all vagueness in understanding the basic design principles. 2. The top of watertight zones of dams should exceed the elevation of the HFL by amounts specified by SNiP. When necessary, in connection with seasonal freezing and thawing of the upper part of the core, additional measures should be provided for ensuring local static stability and seepage strength. 3. Large dams should be evaluated under the aegis of the National Committee on Large Dams, whose role in this matter must be increased. It is necessary to establish legislatively the procedure of changing the designs of dams after approving the projects. 4. A coordination center processing all information on construction and operation should be created for large dams and dams being constructed in the northern construction-climatic zone. The best solutions should be recommended for implementation. 5. It is necessary to reconstruct the upper part of the dams of the Kureika hydrodevelopment, using above the NPL soils of an analogous composition for the entire zone of the core with provision of its seepage strength by an additional filter layer of sorted sand of fractions 0–10 mm. Reconstruction of the dam crests will make it possible not only to obtain additional power production due to the prism of the reservoir between the NPL and HFL within 150–200 million kWh/yr.

In the last three decades the design of stepped spillways regained some interest because of their suitability with new construction methods including gabion placement. In this study, the hydraulic performances of gabion stepped weirs were investigated experimentally in terms of the air-water flow properties and energy dissipation rate. A physical study was performed in a relatively large size facility with a 26.6° slope (1V:2H) and 0.10 m step height. For both gabion and impervious stepped weirs, a detailed comparison of the air-water flow properties was performed. The visual observations highlighted the seepage flow through the gabions, including a modification of the cavity flow dynamics, especially in the skimming flow regime. In skimming flows, higher velocities were measured at the downstream end of the gabion stepped chute, associated with lesser energy dissipation rates.

The 2011 off the Pacific Coast of Tohoku Earthquake on the 11th of March, 2011 had induced a gigantic Tsunami and caused the catastrophic damage in the northeast coast area of Japan. Lots of breakwaters have been seriously damaged in this disaster, including the world deepest breakwaters, Kamaishi Harbor Mouth Breakwaters. According to a wave height recorder, a large hydraulic head difference between the seaside and harbor side of breakwaters was observed for long duration of several minutes or more. Such a hydraulic head difference as observed generates the seepage flow in the rubble mound underneath the caisson. The seepage flow is considered one of the influential factors causing the instability of caisson type composite breakwaters. In order to find out the instability mechanism of caisson type composite breakwaters against tsunami, 1) the pop-out phenomena of armored blocks on the mound, 2) the possibility of shear failure of rubble mound and 3) the reduction of bearing capacity of rubble mound due to seepage flow are investigated. Both theoretical analysis and laboratory experiment are represented in this paper. The safety factors for the pop-out failure and shear failure of rubble mound were theoretically derived. A scale of 1/100 model experiment was performed in laboratory. Loading tests were carried out to investigate the reduction of bearing capacity under the existence of seepage flow. From the results of laboratory experiment and theoretical analysis, it was confirmed that the pop-out phenomenon happens and the bearing capacity of rubble mound can considerably decrease due to the tsunami-induced seepage flow. It is concluded that the effect of seepage flow in the rubble mound should be taken into account when making a design of the caisson type composite breakwater against tsunami.

1. The main problems when designing pressure tunnels are the maximum use of the bearing properties of the enclosing soil mass and prevention of leakage of water from the structure into the mass. The first condition is fulfilled completely in the case of using unlined tunnels, but here the second problem is not always solved. The optimal solution satisfying both requirements in high-head tunnels is the use of a combined lining consisting of an inner steel lining and outer concrete ring. 2. The length (boundary) of the steel lining in a pressure tunnel is determined on the basis of two criteria: the bearing capacity of the rock mass; the size and length of the seepage path from the tunnel into “dry” underground workings or to an open slope. 3. The criteria of the bearing capacity of the rock mass is characterized by two main parameters: deformation-strength characteristics and height of the stratum covering the tunnel. 4. The criterion of the size and length of the seepage path is determined by the seepage strength of the rock mass and stability of the underground workings an open, slopes located in the zone of the seepage flow issuing from the tunnel. 5. At present there is no unified method of determining the boundaries of a steel lining in pressure tunnels. This problem is solved in each particular case with consideration of the engineering-geologic, topographic, technological, operating, and economic conditions.

The results of an experimental investigation on the drivability of helix-shaped units into submerged sand and sand subjected to upward seepage flow are presented. In this research study, the helical units are used as structural anchoring elements. A testing program is conducted to study the effect of water existence in a sand deposit on the driving moment (torque) required to install helix-shaped units, with reference to torque required to install the same in dry sands. Dense sand is used in this study with water conditions varying from hydrostatic pressure to upward seepage flow with three different velocities. Measurements are recorded for the installation torque versus depth of installation. Based on the results of this study, it is concluded that the existence of water in the sand bed material facilitates the installation and reduces the torque required to drive the helical units. It is also found that helix drivability improves with the increase of the velocity of seepage flow, however, this seepage flow negatively reflects on the resistibility of these units to pullout forces. It is recommended that the design of both the driving technique and the pullout resistance of helix-shaped foundation units be balanced in a way that the easiness of installation and the obtained pullout resistance are optimized. It is also recommended that pullout resistance of anchors should not be compromised to achieve higher drivability.

The powerhouse of Jinnah Hydropower Station on Indus River in Pakistan is sitting on a deep overburden layer with maximum depth of 200m. A three- dimensional (3-D) finite element model of seepage flow is set up, which can represent the project geological structure and the geometry boundary of the powerhouse foundation. The influence of different layout schemes to seepage filed of foundation is analyzed and compared in detail, such as setting up the high pressure jet grouting cut-off wall (HPJGCW) and its depth, different number and space between drainage wells etc. An optimizing drainage system of powerhouse foundation pit during the construction stage is put forward. The optimizing drainage system is Scheme 3, which is drainage ditches on ground surface with outer round of HPJGCW and drainage ditches of foundation pit.

1. In certain cases of constructing dams salt-containing soils serve as their foundation. 2. Under these conditions reliable operation of the structures can be provided only by developing special engineering measures to control dissolution. 3. All existing methods of protecting saliferous foundation soils of hydraulic structures from dissolution can be divided into passive, active, and combined. 4. The combined methods should be considered the most effective for preventing removal of salts from foundation soils by the seepage flow. 5. Large-scale field investigations of the work of the combined method of protecting saliferous foundation soils of the planned Lower Kafirnigan hydro development showed its high effectiveness even in the case of complex engineering-geological conditions at the construction site. 6. Individual elements of the set of dissolution protective measures investigated under field conditions can be used in hydrotechnical and hydropower construction practice.

急潮流が作用する明石海峡大橋主塔基礎の捨石洗掘防止工の設計を目的として, 捨石洗掘防止工下の基盤に作用する浸透流速を予測するために浸透流模型実験を, 基盤の洗掘抵抗性を把握するために現地地質ボーリング資料を用いて洗掘抵抗実験を行った. これらの結果を用いて設計した3P主塔基礎において, 捨石洗掘防止工の施工に合わせて, 捨石洗掘防止工内の浸透流速等を現地計測した, 模型実験および現地計測結果により捨石洗掘防止工の有効性を確認し, 主塔基礎回りの水面勾配, 捨石の層厚, 透水係数と捨石洗掘防止工下の基盤に作用する浸透流速の関係を明らかにした.

Based on the concept of ‘true air element’ and ‘true node’ proposed by the authors for the modelling of changing mesh problems in geotechnical problems, a simple but efficient finite element procedure for the solution of free surface seepage flow is developed. In the present method, the mesh used for the analysis will remain unchanged. Very rapid convergence with significant reduction in solution time and computer memory are achieved with the proposed method. Some interesting results in the seepage flow problems which are commonly overlooked are also discussed.

High seepage flow velocities represent a potential problem for Artificial Ground Freezing (AGF) because they may hinder the formation of a closed ice body. Due to the complexity of the physical mechanisms involved, numerical thermal and seepage flow analyses are often indispensable for design. The underlying models must be verified against results obtained from appropriate physical simulations. Since information on such results is very limited in the literature, it has been necessary to develop a new large-scale physical model for AGF. All of the relevant material parameters were determined independently from the tests, so the experimental results presented here may serve as a database for the verification of numerical models, especially in the case of 3-D problems.

An impermeable boundary of the grout cutoff has been found that maximizes the seepage flow for a specified grouting volume. The shape of a trench has been defined that maximizes the quantity of fluid entering the ground-water flow from the trench. The seepage characteristics of the grout cutoff and the trench which have arbitrary shapes are estimated in terms of the derived exact analytical solutions of variational problems.

The presently existing methods or calculating seepage in inclined ASEs have a limited area of use and often give substantial deviations from the actual values. At the same time, no analytical relations are known for calculating Iex in the backwater zone of the LP. The formulas proposed in the article permit determining all main parameters of the seepage flow, including separately for the zones of effluent seepage and backwater of the LP, with an accuracy sufficient for engineering calculations.

1. The observations and installed control-measurement instruments on the whole ensured the required control conditions for the rock-earth dam of the Hoabinh hydraulic development and the carrying out of analyses of its state. 2. An analysis of the structure behavior performed using data from instrumental observations showed that the stress-strain conditions of the dam are favorable and correspond to the requirements intended to ensure its reliable operation. The development and distribution of the stress-strain conditions of the dam conform to the design assumptions. Earthquakes in the hydraulic-development region did not affect the process of development of the measurable deformations. 3. The results of observations of the seepage regime of the dam and the base indicate normal operating conditions. The hydraulic gradients on the curtain and the base do not exceed the allowable values. The antifiltration curtain effectiveness is uniform along the front and is stable with time. 4. An analysis of the full-scale observation results performed when construction of the structure was completed showed that the dam body settlements are in the attenuation phase, that the pore pressure dissipation process has been practically completed, and that the parameters of seepage flow in the dam and the base are below the allowable values. The structure state indices permit giving an optimistic prediction of reliability of the dam under rise of the reservoir water elevation to the NPL.

In 2011, the example that breakwaters collapsed because of the basic ground’s destabilization was reported by Tohoku-Kanto earthquake tsunami. Fluid-Structure-Soil coupling simulation is desired for a systematic comprehension of the breakwater collapse mechanism, and it may help to develop next disaster prevention method. In this study, A particle simulation tool based on the SPH has been modified and improved to analyze seepage flow and soil scouring. In seepage flow analysis, as a first step, this simulation treat the surface flow and seepage flow interactions by using governing equation. In the scouring analysis, soil scour is judged by an empirical criteria based on quicksand quantity formula.