The Influence of Internal Erosion in Earthen Dams on the Potential Difference Response to Applied Voltage

Internal erosion is widely perceived as contributing to the failure of earthen dams. To reduce the failure risk, timely monitoring of internal erosion is an effective method in observing their internal structure evolution. A set of earthen dam model experiments were conducted. Under an applied voltage, the response potential differences (PD) at the slope of the dam models were collected before and after the impoundment of the upstream reservoir. The discrepancy among the four dam models, the influence of soil moisture content on PD, and the impact of internal erosion on PD were studied. The results show that it is acceptable to employ different dam models to simulate the development of internal erosion, although the discrepancy among the models is inevitable. The moisture content of the soil significantly affects the PD response to applied voltage. The PD increases with an increase in soil moisture content until the soil is saturated. The change in PD is correlated with the development of internal erosion. With the progression of internal erosion, the starting position for the steep increase in PD distribution continues to move toward the dam toe. In addition, the electrode stability is noted to have an effect on measured PD, which requires further studies to be clarified. This study sets the stage for the PD-based monitoring method in observing the evolution of internal erosion in earthen dams.

Permeability Analysis of Dredged Material and Its Stabilization Using Surkhi/Brick Dust

This study presents the permeability and strong relationship of dredged soil stabilized with surkhi/brick dust which is to be used for constructing road embankments. Tests like the unconfined compressive strength test and the falling head permeability test were conducted. The test results showed that as the percentage replacement of surkhi increases, the samples become less permeable. Showing that the surkhi tends to cover up the pore spaces of the soil, causing the water to have fewer passageways. Large amount of sediments are dredged from rivers and lakes as a result of environmental dredging in India. These dredged materials (DM) have poor Geotechnical properties and are normally treated as wastes. On the other Hand, there is a huge demand of sub-grade materials due to the increasing number of highway construction projects in the J&K. Thus, the reuse of the dredged material as sub-grade material may be considered as an Environmental-friendly and economical option. For the stabilization of dredged material various waste materials can be effectively used. brick dust is one such waste product. The surkhi/brick dust is generated from brick kilns. The amount of brick dust produced every year is in the range of 3-4 million ton. This project therefore intends to study the stabilization of dredged material procured from Sindh Nallah having a higher content of alluvial Soil using Surkhi/Brick dust as an additive. Soil stabilization by this means can be utilized on airport pavements, highway pavements, earthen dams and many other situations where sub-soils are not suitable for construction. Keywords: dredged material Sindh Nallah, surkhi, Dredged soil, CBR, UCS, proctor test, porosity, void ratio and permeability

Settlement Analysis of Dredged Material and Its Stabilization Using Surkhi/Brick Dust

Soil stabilization is the phenomenon by virtue of which the soils are altered to enhance their physical Properties. The process aims to increase the shear Strength of soil thus improving its load bearing capacity to support pavements and foundations. Diverse range of soil materials varying from Expansive clays to granular materials can be treated by a diverse set of Additives like silica, lime, fly-ash, cement and so on. In J&K, the most common types of soils are the alluvial soils which get deposited in river beds as a result of sedimentation. River Jhelum in J&K is one of the major hotspots for accumulated sediments with an estimate of about 36 lakh cubic meters of sediments in its river bed, leaving very little space in it to take excess water. Subsequently, it is severely threatened by the Phenomena of still higher levels of sedimentation and hence consequent Floods. Dredging practices are a challenge for the maintenance of rivers and their Spillways. In Geotechnical Engineering, the valorisation of dredging Sediments and their Use in public works is increasingly prospected by Researchers in recent Years. Moreover, Floods in Kashmir valley in September 2014 compelled the Govt. Of Jammu and Kashmir to take Necessary steps in order to avoid similar situation in near future. This project therefore intends to study the stabilization of dredged material procured from Sindh Nallah having a higher content of alluvial Soil using Surkhi/Brick dust as an additive. Soil stabilization by this means can be utilized on airport pavements, highway pavements, earthen dams and many other situations where sub-soils are not suitable for construction. Keywords: Sindh Nallah, Dredged material, Surkhi, OMC, MDD, CBR, Direct Shear test.

Effect of Silica Fume as a Waste Material for Sustainable Environment on the Stabilization and Dynamic Behavior of Dispersive Soil

The use of dispersive soils, which are common in many parts of the world, in engineering applications such as water structures, earthen dams and road embankments is possible with their improvement. Recently, the effects of different chemicals on the stabilization of dispersive soils have been investigated. The use of waste materials in stabilization is preferred both because of the more sustainable environment and the economic advantages it provides. The use of silica fume (SF) as a waste material in different engineering applications provides an important advantage in environmentally and economically sustainable ways. Many studies have been carried out regarding silica fume, especially in the construction industry. Although SF is used in many industries, there is no study about its potential impact on the stabilization and dynamic properties of dispersive soils. In this study, first, Atterberg limits and standard Proctor compaction tests were performed on the mixtures prepared by adding different SF percentages (0, 5, 10, 15, 20, 25 and 30%). Afterward, pinhole tests and resonant column tests were performed to determine dispersibility and dynamic properties on the samples prepared by compaction characteristics for each SF percentage reached. In general, it was determined that SF contributed to a change in soil class, and improvement in dispersibility and dynamic properties of the soil sample, depending on SF content; positive effects of SF were observed in terms of shallow soil improvement.

Finite element analysis for identifying locations of cracking and hydraulic fracturing in homogeneous earthen dams

This paper reports a finite element study to identify the locations of crack initiation in a homogeneous earthen dam at its post-construction and reservoir operation stages. The steady state and transient analyses, including reservoir rise-up and drawdown conditions, are simulated to identify the favorable conditions and locations of crack generation. The behavioral response of the dam is represented in terms of the developed total stress, horizontal deformations of the faces, strain accumulation in the dam, and the differential settlement of the dam base. The locations of post-construction cracks are identified based on the negative minor principal stresses developed on the dam faces. For both single-lift and multiple-lift modeling techniques, the upstream face of the dam is found to be the most favorable location for the crack generation. For transient reservoir operations (rise-up and drawdown scenarios), it is identified that hydraulic fracturing may occur on either faces of the dam at specific heights, governed by the minor principal stresses becoming lesser than the developed pore-water pressure. Depending on whether the reservoir drawdown occurs before or after the attainment of steady-state phreatic level within the body of the dam, the pore-water pressure distribution within the dam are found notably different. This results in hydraulic fracturing occurring at different faces of the dam and at different heights. It is important to have a thorough understanding of the tentative location of the cracks developed in homogeneous earthen dams so that proper mitigation measure can be adopted as per requirement.

Dam-Break analysis: proposal of a simplified approach

ABSTRACT Simplified methods are useful alternatives for prior analysis of the effects of dam rupture and can guide the decision-making process for carrying out more complete studies. In this context, a new simplified approach is presented, which enables the analysis of aspects from dam rupture of earthen dams that failed due to overtopping, considering dam height and reservoir volume as input data. Hypothetical cases were analyzed applying dam-break hydrodynamic simulations, which results allowed the development of equations capable of estimating peak flow attenuation and peak discharge arrival time along the downstream valley. The proposed approach was applied in a hypothetical case study (15 m high dam and 17 hm3 reservoir volume), obtaining results close to those achieved through other methods, especially in case of estimating the maximum discharges throughout the downstream valley, where the average differences between the results of the methods were of the order of 15%.